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-rw-r--r--synapse/handlers/_base.py76
-rw-r--r--synapse/handlers/account_data.py20
-rw-r--r--synapse/handlers/account_validity.py92
-rw-r--r--synapse/handlers/acme.py16
-rw-r--r--synapse/handlers/admin.py123
-rw-r--r--synapse/handlers/appservice.py5
-rw-r--r--synapse/handlers/auth.py892
-rw-r--r--synapse/handlers/cas_handler.py221
-rw-r--r--synapse/handlers/deactivate_account.py84
-rw-r--r--synapse/handlers/device.py236
-rw-r--r--synapse/handlers/devicemessage.py65
-rw-r--r--synapse/handlers/directory.py254
-rw-r--r--synapse/handlers/e2e_keys.py882
-rw-r--r--synapse/handlers/e2e_room_keys.py141
-rw-r--r--synapse/handlers/events.py52
-rw-r--r--synapse/handlers/federation.py1666
-rw-r--r--synapse/handlers/groups_local.py354
-rw-r--r--synapse/handlers/identity.py633
-rw-r--r--synapse/handlers/initial_sync.py160
-rw-r--r--synapse/handlers/message.py521
-rw-r--r--synapse/handlers/oidc_handler.py1049
-rw-r--r--synapse/handlers/pagination.py167
-rw-r--r--synapse/handlers/password_policy.py93
-rw-r--r--synapse/handlers/presence.py430
-rw-r--r--synapse/handlers/profile.py77
-rw-r--r--synapse/handlers/read_marker.py13
-rw-r--r--synapse/handlers/receipts.py39
-rw-r--r--synapse/handlers/register.py233
-rw-r--r--synapse/handlers/room.py556
-rw-r--r--synapse/handlers/room_list.py375
-rw-r--r--synapse/handlers/room_member.py962
-rw-r--r--synapse/handlers/room_member_worker.py41
-rw-r--r--synapse/handlers/saml_handler.py363
-rw-r--r--synapse/handlers/search.py100
-rw-r--r--synapse/handlers/set_password.py47
-rw-r--r--synapse/handlers/state_deltas.py9
-rw-r--r--synapse/handlers/stats.py67
-rw-r--r--synapse/handlers/sync.py979
-rw-r--r--synapse/handlers/typing.py28
-rw-r--r--synapse/handlers/ui_auth/__init__.py22
-rw-r--r--synapse/handlers/ui_auth/checkers.py246
-rw-r--r--synapse/handlers/user_directory.py149
42 files changed, 8228 insertions, 4310 deletions
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index d15c6282fb..61dc4beafe 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -19,7 +19,7 @@ from twisted.internet import defer
 
 import synapse.types
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import LimitExceededError
+from synapse.api.ratelimiting import Ratelimiter
 from synapse.types import UserID
 
 logger = logging.getLogger(__name__)
@@ -44,11 +44,26 @@ class BaseHandler(object):
         self.notifier = hs.get_notifier()
         self.state_handler = hs.get_state_handler()
         self.distributor = hs.get_distributor()
-        self.ratelimiter = hs.get_ratelimiter()
-        self.admin_redaction_ratelimiter = hs.get_admin_redaction_ratelimiter()
         self.clock = hs.get_clock()
         self.hs = hs
 
+        # The rate_hz and burst_count are overridden on a per-user basis
+        self.request_ratelimiter = Ratelimiter(
+            clock=self.clock, rate_hz=0, burst_count=0
+        )
+        self._rc_message = self.hs.config.rc_message
+
+        # Check whether ratelimiting room admin message redaction is enabled
+        # by the presence of rate limits in the config
+        if self.hs.config.rc_admin_redaction:
+            self.admin_redaction_ratelimiter = Ratelimiter(
+                clock=self.clock,
+                rate_hz=self.hs.config.rc_admin_redaction.per_second,
+                burst_count=self.hs.config.rc_admin_redaction.burst_count,
+            )
+        else:
+            self.admin_redaction_ratelimiter = None
+
         self.server_name = hs.hostname
 
         self.event_builder_factory = hs.get_event_builder_factory()
@@ -70,7 +85,6 @@ class BaseHandler(object):
         Raises:
             LimitExceededError if the request should be ratelimited
         """
-        time_now = self.clock.time()
         user_id = requester.user.to_string()
 
         # The AS user itself is never rate limited.
@@ -83,73 +97,55 @@ class BaseHandler(object):
         if requester.app_service and not requester.app_service.is_rate_limited():
             return
 
+        messages_per_second = self._rc_message.per_second
+        burst_count = self._rc_message.burst_count
+
         # Check if there is a per user override in the DB.
         override = yield self.store.get_ratelimit_for_user(user_id)
         if override:
-            # If overriden with a null Hz then ratelimiting has been entirely
+            # If overridden with a null Hz then ratelimiting has been entirely
             # disabled for the user
             if not override.messages_per_second:
                 return
 
             messages_per_second = override.messages_per_second
             burst_count = override.burst_count
+
+        if is_admin_redaction and self.admin_redaction_ratelimiter:
+            # If we have separate config for admin redactions, use a separate
+            # ratelimiter as to not have user_ids clash
+            self.admin_redaction_ratelimiter.ratelimit(user_id, update=update)
         else:
-            # We default to different values if this is an admin redaction and
-            # the config is set
-            if is_admin_redaction and self.hs.config.rc_admin_redaction:
-                messages_per_second = self.hs.config.rc_admin_redaction.per_second
-                burst_count = self.hs.config.rc_admin_redaction.burst_count
-            else:
-                messages_per_second = self.hs.config.rc_message.per_second
-                burst_count = self.hs.config.rc_message.burst_count
-
-        if is_admin_redaction and self.hs.config.rc_admin_redaction:
-            # If we have separate config for admin redactions we use a separate
-            # ratelimiter
-            allowed, time_allowed = self.admin_redaction_ratelimiter.can_do_action(
-                user_id,
-                time_now,
-                rate_hz=messages_per_second,
-                burst_count=burst_count,
-                update=update,
-            )
-        else:
-            allowed, time_allowed = self.ratelimiter.can_do_action(
+            # Override rate and burst count per-user
+            self.request_ratelimiter.ratelimit(
                 user_id,
-                time_now,
                 rate_hz=messages_per_second,
                 burst_count=burst_count,
                 update=update,
             )
-        if not allowed:
-            raise LimitExceededError(
-                retry_after_ms=int(1000 * (time_allowed - time_now))
-            )
 
-    @defer.inlineCallbacks
-    def maybe_kick_guest_users(self, event, context=None):
+    async def maybe_kick_guest_users(self, event, context=None):
         # Technically this function invalidates current_state by changing it.
         # Hopefully this isn't that important to the caller.
         if event.type == EventTypes.GuestAccess:
             guest_access = event.content.get("guest_access", "forbidden")
             if guest_access != "can_join":
                 if context:
-                    current_state_ids = yield context.get_current_state_ids(self.store)
-                    current_state = yield self.store.get_events(
+                    current_state_ids = await context.get_current_state_ids()
+                    current_state = await self.store.get_events(
                         list(current_state_ids.values())
                     )
                 else:
-                    current_state = yield self.state_handler.get_current_state(
+                    current_state = await self.state_handler.get_current_state(
                         event.room_id
                     )
 
                 current_state = list(current_state.values())
 
                 logger.info("maybe_kick_guest_users %r", current_state)
-                yield self.kick_guest_users(current_state)
+                await self.kick_guest_users(current_state)
 
-    @defer.inlineCallbacks
-    def kick_guest_users(self, current_state):
+    async def kick_guest_users(self, current_state):
         for member_event in current_state:
             try:
                 if member_event.type != EventTypes.Member:
@@ -180,7 +176,7 @@ class BaseHandler(object):
                 # homeserver.
                 requester = synapse.types.create_requester(target_user, is_guest=True)
                 handler = self.hs.get_room_member_handler()
-                yield handler.update_membership(
+                await handler.update_membership(
                     requester,
                     target_user,
                     member_event.room_id,
diff --git a/synapse/handlers/account_data.py b/synapse/handlers/account_data.py
index 38bc67191c..a8d3fbc6de 100644
--- a/synapse/handlers/account_data.py
+++ b/synapse/handlers/account_data.py
@@ -13,8 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
 
 class AccountDataEventSource(object):
     def __init__(self, hs):
@@ -23,24 +21,24 @@ class AccountDataEventSource(object):
     def get_current_key(self, direction="f"):
         return self.store.get_max_account_data_stream_id()
 
-    @defer.inlineCallbacks
-    def get_new_events(self, user, from_key, **kwargs):
+    async def get_new_events(self, user, from_key, **kwargs):
         user_id = user.to_string()
         last_stream_id = from_key
 
-        current_stream_id = yield self.store.get_max_account_data_stream_id()
+        current_stream_id = self.store.get_max_account_data_stream_id()
 
         results = []
-        tags = yield self.store.get_updated_tags(user_id, last_stream_id)
+        tags = await self.store.get_updated_tags(user_id, last_stream_id)
 
         for room_id, room_tags in tags.items():
             results.append(
                 {"type": "m.tag", "content": {"tags": room_tags}, "room_id": room_id}
             )
 
-        account_data, room_account_data = (
-            yield self.store.get_updated_account_data_for_user(user_id, last_stream_id)
-        )
+        (
+            account_data,
+            room_account_data,
+        ) = await self.store.get_updated_account_data_for_user(user_id, last_stream_id)
 
         for account_data_type, content in account_data.items():
             results.append({"type": account_data_type, "content": content})
@@ -52,7 +50,3 @@ class AccountDataEventSource(object):
                 )
 
         return results, current_stream_id
-
-    @defer.inlineCallbacks
-    def get_pagination_rows(self, user, config, key):
-        return [], config.to_id
diff --git a/synapse/handlers/account_validity.py b/synapse/handlers/account_validity.py
index d04e0fe576..590135d19c 100644
--- a/synapse/handlers/account_validity.py
+++ b/synapse/handlers/account_validity.py
@@ -18,8 +18,7 @@ import email.utils
 import logging
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
-
-from twisted.internet import defer
+from typing import List
 
 from synapse.api.errors import StoreError
 from synapse.logging.context import make_deferred_yieldable
@@ -45,7 +44,11 @@ class AccountValidityHandler(object):
 
         self._account_validity = self.hs.config.account_validity
 
-        if self._account_validity.renew_by_email_enabled and load_jinja2_templates:
+        if (
+            self._account_validity.enabled
+            and self._account_validity.renew_by_email_enabled
+            and load_jinja2_templates
+        ):
             # Don't do email-specific configuration if renewal by email is disabled.
             try:
                 app_name = self.hs.config.email_app_name
@@ -78,42 +81,39 @@ class AccountValidityHandler(object):
                 # run as a background process to make sure that the database transactions
                 # have a logcontext to report to
                 return run_as_background_process(
-                    "send_renewals", self.send_renewal_emails
+                    "send_renewals", self._send_renewal_emails
                 )
 
             self.clock.looping_call(send_emails, 30 * 60 * 1000)
 
-    @defer.inlineCallbacks
-    def send_renewal_emails(self):
+    async def _send_renewal_emails(self):
         """Gets the list of users whose account is expiring in the amount of time
         configured in the ``renew_at`` parameter from the ``account_validity``
         configuration, and sends renewal emails to all of these users as long as they
         have an email 3PID attached to their account.
         """
-        expiring_users = yield self.store.get_users_expiring_soon()
+        expiring_users = await self.store.get_users_expiring_soon()
 
         if expiring_users:
             for user in expiring_users:
-                yield self._send_renewal_email(
+                await self._send_renewal_email(
                     user_id=user["user_id"], expiration_ts=user["expiration_ts_ms"]
                 )
 
-    @defer.inlineCallbacks
-    def send_renewal_email_to_user(self, user_id):
-        expiration_ts = yield self.store.get_expiration_ts_for_user(user_id)
-        yield self._send_renewal_email(user_id, expiration_ts)
+    async def send_renewal_email_to_user(self, user_id: str):
+        expiration_ts = await self.store.get_expiration_ts_for_user(user_id)
+        await self._send_renewal_email(user_id, expiration_ts)
 
-    @defer.inlineCallbacks
-    def _send_renewal_email(self, user_id, expiration_ts):
+    async def _send_renewal_email(self, user_id: str, expiration_ts: int):
         """Sends out a renewal email to every email address attached to the given user
         with a unique link allowing them to renew their account.
 
         Args:
-            user_id (str): ID of the user to send email(s) to.
-            expiration_ts (int): Timestamp in milliseconds for the expiration date of
+            user_id: ID of the user to send email(s) to.
+            expiration_ts: Timestamp in milliseconds for the expiration date of
                 this user's account (used in the email templates).
         """
-        addresses = yield self._get_email_addresses_for_user(user_id)
+        addresses = await self._get_email_addresses_for_user(user_id)
 
         # Stop right here if the user doesn't have at least one email address.
         # In this case, they will have to ask their server admin to renew their
@@ -125,7 +125,7 @@ class AccountValidityHandler(object):
             return
 
         try:
-            user_display_name = yield self.store.get_profile_displayname(
+            user_display_name = await self.store.get_profile_displayname(
                 UserID.from_string(user_id).localpart
             )
             if user_display_name is None:
@@ -133,7 +133,7 @@ class AccountValidityHandler(object):
         except StoreError:
             user_display_name = user_id
 
-        renewal_token = yield self._get_renewal_token(user_id)
+        renewal_token = await self._get_renewal_token(user_id)
         url = "%s_matrix/client/unstable/account_validity/renew?token=%s" % (
             self.hs.config.public_baseurl,
             renewal_token,
@@ -165,7 +165,7 @@ class AccountValidityHandler(object):
 
             logger.info("Sending renewal email to %s", address)
 
-            yield make_deferred_yieldable(
+            await make_deferred_yieldable(
                 self.sendmail(
                     self.hs.config.email_smtp_host,
                     self._raw_from,
@@ -180,19 +180,18 @@ class AccountValidityHandler(object):
                 )
             )
 
-        yield self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
+        await self.store.set_renewal_mail_status(user_id=user_id, email_sent=True)
 
-    @defer.inlineCallbacks
-    def _get_email_addresses_for_user(self, user_id):
+    async def _get_email_addresses_for_user(self, user_id: str) -> List[str]:
         """Retrieve the list of email addresses attached to a user's account.
 
         Args:
-            user_id (str): ID of the user to lookup email addresses for.
+            user_id: ID of the user to lookup email addresses for.
 
         Returns:
-            defer.Deferred[list[str]]: Email addresses for this account.
+            Email addresses for this account.
         """
-        threepids = yield self.store.user_get_threepids(user_id)
+        threepids = await self.store.user_get_threepids(user_id)
 
         addresses = []
         for threepid in threepids:
@@ -201,16 +200,15 @@ class AccountValidityHandler(object):
 
         return addresses
 
-    @defer.inlineCallbacks
-    def _get_renewal_token(self, user_id):
+    async def _get_renewal_token(self, user_id: str) -> str:
         """Generates a 32-byte long random string that will be inserted into the
         user's renewal email's unique link, then saves it into the database.
 
         Args:
-            user_id (str): ID of the user to generate a string for.
+            user_id: ID of the user to generate a string for.
 
         Returns:
-            defer.Deferred[str]: The generated string.
+            The generated string.
 
         Raises:
             StoreError(500): Couldn't generate a unique string after 5 attempts.
@@ -219,52 +217,52 @@ class AccountValidityHandler(object):
         while attempts < 5:
             try:
                 renewal_token = stringutils.random_string(32)
-                yield self.store.set_renewal_token_for_user(user_id, renewal_token)
+                await self.store.set_renewal_token_for_user(user_id, renewal_token)
                 return renewal_token
             except StoreError:
                 attempts += 1
         raise StoreError(500, "Couldn't generate a unique string as refresh string.")
 
-    @defer.inlineCallbacks
-    def renew_account(self, renewal_token):
+    async def renew_account(self, renewal_token: str) -> bool:
         """Renews the account attached to a given renewal token by pushing back the
         expiration date by the current validity period in the server's configuration.
 
         Args:
-            renewal_token (str): Token sent with the renewal request.
+            renewal_token: Token sent with the renewal request.
         Returns:
-            bool: Whether the provided token is valid.
+            Whether the provided token is valid.
         """
         try:
-            user_id = yield self.store.get_user_from_renewal_token(renewal_token)
+            user_id = await self.store.get_user_from_renewal_token(renewal_token)
         except StoreError:
-            defer.returnValue(False)
+            return False
 
         logger.debug("Renewing an account for user %s", user_id)
-        yield self.renew_account_for_user(user_id)
+        await self.renew_account_for_user(user_id)
 
-        defer.returnValue(True)
+        return True
 
-    @defer.inlineCallbacks
-    def renew_account_for_user(self, user_id, expiration_ts=None, email_sent=False):
+    async def renew_account_for_user(
+        self, user_id: str, expiration_ts: int = None, email_sent: bool = False
+    ) -> int:
         """Renews the account attached to a given user by pushing back the
         expiration date by the current validity period in the server's
         configuration.
 
         Args:
-            renewal_token (str): Token sent with the renewal request.
-            expiration_ts (int): New expiration date. Defaults to now + validity period.
-            email_sent (bool): Whether an email has been sent for this validity period.
+            renewal_token: Token sent with the renewal request.
+            expiration_ts: New expiration date. Defaults to now + validity period.
+            email_sen: Whether an email has been sent for this validity period.
                 Defaults to False.
 
         Returns:
-            defer.Deferred[int]: New expiration date for this account, as a timestamp
-                in milliseconds since epoch.
+            New expiration date for this account, as a timestamp in
+            milliseconds since epoch.
         """
         if expiration_ts is None:
             expiration_ts = self.clock.time_msec() + self._account_validity.period
 
-        yield self.store.set_account_validity_for_user(
+        await self.store.set_account_validity_for_user(
             user_id=user_id, expiration_ts=expiration_ts, email_sent=email_sent
         )
 
diff --git a/synapse/handlers/acme.py b/synapse/handlers/acme.py
index 46ac73106d..a2d7959abe 100644
--- a/synapse/handlers/acme.py
+++ b/synapse/handlers/acme.py
@@ -25,6 +25,15 @@ from synapse.app import check_bind_error
 
 logger = logging.getLogger(__name__)
 
+ACME_REGISTER_FAIL_ERROR = """
+--------------------------------------------------------------------------------
+Failed to register with the ACME provider. This is likely happening because the installation
+is new, and ACME v1 has been deprecated by Let's Encrypt and disabled for
+new installations since November 2019.
+At the moment, Synapse doesn't support ACME v2. For more information and alternative
+solutions, please read https://github.com/matrix-org/synapse/blob/master/docs/ACME.md#deprecation-of-acme-v1
+--------------------------------------------------------------------------------"""
+
 
 class AcmeHandler(object):
     def __init__(self, hs):
@@ -71,7 +80,12 @@ class AcmeHandler(object):
         # want it to control where we save the certificates, we have to reach in
         # and trigger the registration machinery ourselves.
         self._issuer._registered = False
-        yield self._issuer._ensure_registered()
+
+        try:
+            yield self._issuer._ensure_registered()
+        except Exception:
+            logger.error(ACME_REGISTER_FAIL_ERROR)
+            raise
 
     @defer.inlineCallbacks
     def provision_certificate(self):
diff --git a/synapse/handlers/admin.py b/synapse/handlers/admin.py
index 1a87b58838..f3c0aeceb6 100644
--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -14,11 +14,11 @@
 # limitations under the License.
 
 import logging
-
-from twisted.internet import defer
+from typing import List
 
 from synapse.api.constants import Membership
-from synapse.types import RoomStreamToken
+from synapse.events import FrozenEvent
+from synapse.types import RoomStreamToken, StateMap
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
@@ -30,11 +30,13 @@ class AdminHandler(BaseHandler):
     def __init__(self, hs):
         super(AdminHandler, self).__init__(hs)
 
-    @defer.inlineCallbacks
-    def get_whois(self, user):
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
+
+    async def get_whois(self, user):
         connections = []
 
-        sessions = yield self.store.get_user_ip_and_agents(user)
+        sessions = await self.store.get_user_ip_and_agents(user)
         for session in sessions:
             connections.append(
                 {
@@ -51,70 +53,18 @@ class AdminHandler(BaseHandler):
 
         return ret
 
-    @defer.inlineCallbacks
-    def get_users(self):
-        """Function to reterive a list of users in users table.
-
-        Args:
-        Returns:
-            defer.Deferred: resolves to list[dict[str, Any]]
-        """
-        ret = yield self.store.get_users()
-
-        return ret
-
-    @defer.inlineCallbacks
-    def get_users_paginate(self, order, start, limit):
-        """Function to reterive a paginated list of users from
-        users list. This will return a json object, which contains
-        list of users and the total number of users in users table.
-
-        Args:
-            order (str): column name to order the select by this column
-            start (int): start number to begin the query from
-            limit (int): number of rows to reterive
-        Returns:
-            defer.Deferred: resolves to json object {list[dict[str, Any]], count}
-        """
-        ret = yield self.store.get_users_paginate(order, start, limit)
-
+    async def get_user(self, user):
+        """Function to get user details"""
+        ret = await self.store.get_user_by_id(user.to_string())
+        if ret:
+            profile = await self.store.get_profileinfo(user.localpart)
+            threepids = await self.store.user_get_threepids(user.to_string())
+            ret["displayname"] = profile.display_name
+            ret["avatar_url"] = profile.avatar_url
+            ret["threepids"] = threepids
         return ret
 
-    @defer.inlineCallbacks
-    def search_users(self, term):
-        """Function to search users list for one or more users with
-        the matched term.
-
-        Args:
-            term (str): search term
-        Returns:
-            defer.Deferred: resolves to list[dict[str, Any]]
-        """
-        ret = yield self.store.search_users(term)
-
-        return ret
-
-    def get_user_server_admin(self, user):
-        """
-        Get the admin bit on a user.
-
-        Args:
-            user_id (UserID): the (necessarily local) user to manipulate
-        """
-        return self.store.is_server_admin(user)
-
-    def set_user_server_admin(self, user, admin):
-        """
-        Set the admin bit on a user.
-
-        Args:
-            user_id (UserID): the (necessarily local) user to manipulate
-            admin (bool): whether or not the user should be an admin of this server
-        """
-        return self.store.set_server_admin(user, admin)
-
-    @defer.inlineCallbacks
-    def export_user_data(self, user_id, writer):
+    async def export_user_data(self, user_id, writer):
         """Write all data we have on the user to the given writer.
 
         Args:
@@ -126,7 +76,7 @@ class AdminHandler(BaseHandler):
             The returned value is that returned by `writer.finished()`.
         """
         # Get all rooms the user is in or has been in
-        rooms = yield self.store.get_rooms_for_user_where_membership_is(
+        rooms = await self.store.get_rooms_for_local_user_where_membership_is(
             user_id,
             membership_list=(
                 Membership.JOIN,
@@ -139,7 +89,7 @@ class AdminHandler(BaseHandler):
         # We only try and fetch events for rooms the user has been in. If
         # they've been e.g. invited to a room without joining then we handle
         # those seperately.
-        rooms_user_has_been_in = yield self.store.get_rooms_user_has_been_in(user_id)
+        rooms_user_has_been_in = await self.store.get_rooms_user_has_been_in(user_id)
 
         for index, room in enumerate(rooms):
             room_id = room.room_id
@@ -148,7 +98,7 @@ class AdminHandler(BaseHandler):
                 "[%s] Handling room %s, %d/%d", user_id, room_id, index + 1, len(rooms)
             )
 
-            forgotten = yield self.store.did_forget(user_id, room_id)
+            forgotten = await self.store.did_forget(user_id, room_id)
             if forgotten:
                 logger.info("[%s] User forgot room %d, ignoring", user_id, room_id)
                 continue
@@ -160,7 +110,7 @@ class AdminHandler(BaseHandler):
 
                 if room.membership == Membership.INVITE:
                     event_id = room.event_id
-                    invite = yield self.store.get_event(event_id, allow_none=True)
+                    invite = await self.store.get_event(event_id, allow_none=True)
                     if invite:
                         invited_state = invite.unsigned["invite_room_state"]
                         writer.write_invite(room_id, invite, invited_state)
@@ -171,7 +121,7 @@ class AdminHandler(BaseHandler):
             # were joined. We estimate that point by looking at the
             # stream_ordering of the last membership if it wasn't a join.
             if room.membership == Membership.JOIN:
-                stream_ordering = yield self.store.get_room_max_stream_ordering()
+                stream_ordering = self.store.get_room_max_stream_ordering()
             else:
                 stream_ordering = room.stream_ordering
 
@@ -197,7 +147,7 @@ class AdminHandler(BaseHandler):
             # events that we have and then filtering, this isn't the most
             # efficient method perhaps but it does guarantee we get everything.
             while True:
-                events, _ = yield self.store.paginate_room_events(
+                events, _ = await self.store.paginate_room_events(
                     room_id, from_key, to_key, limit=100, direction="f"
                 )
                 if not events:
@@ -205,7 +155,7 @@ class AdminHandler(BaseHandler):
 
                 from_key = events[-1].internal_metadata.after
 
-                events = yield filter_events_for_client(self.store, user_id, events)
+                events = await filter_events_for_client(self.storage, user_id, events)
 
                 writer.write_events(room_id, events)
 
@@ -241,7 +191,7 @@ class AdminHandler(BaseHandler):
             for event_id in extremities:
                 if not event_to_unseen_prevs[event_id]:
                     continue
-                state = yield self.store.get_state_for_event(event_id)
+                state = await self.state_store.get_state_for_event(event_id)
                 writer.write_state(room_id, event_id, state)
 
         return writer.finished()
@@ -251,35 +201,26 @@ class ExfiltrationWriter(object):
     """Interface used to specify how to write exported data.
     """
 
-    def write_events(self, room_id, events):
+    def write_events(self, room_id: str, events: List[FrozenEvent]):
         """Write a batch of events for a room.
-
-        Args:
-            room_id (str)
-            events (list[FrozenEvent])
         """
         pass
 
-    def write_state(self, room_id, event_id, state):
+    def write_state(self, room_id: str, event_id: str, state: StateMap[FrozenEvent]):
         """Write the state at the given event in the room.
 
         This only gets called for backward extremities rather than for each
         event.
-
-        Args:
-            room_id (str)
-            event_id (str)
-            state (dict[tuple[str, str], FrozenEvent])
         """
         pass
 
-    def write_invite(self, room_id, event, state):
+    def write_invite(self, room_id: str, event: FrozenEvent, state: StateMap[dict]):
         """Write an invite for the room, with associated invite state.
 
         Args:
-            room_id (str)
-            event (FrozenEvent)
-            state (dict[tuple[str, str], dict]): A subset of the state at the
+            room_id
+            event
+            state: A subset of the state at the
                 invite, with a subset of the event keys (type, state_key
                 content and sender)
         """
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index 3e9b298154..fe62f78e67 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -73,7 +73,10 @@ class ApplicationServicesHandler(object):
             try:
                 limit = 100
                 while True:
-                    upper_bound, events = yield self.store.get_new_events_for_appservice(
+                    (
+                        upper_bound,
+                        events,
+                    ) = yield self.store.get_new_events_for_appservice(
                         self.current_max, limit
                     )
 
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 374372b69e..119678e67b 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -17,14 +17,12 @@
 import logging
 import time
 import unicodedata
+import urllib.parse
+from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple, Union
 
 import attr
-import bcrypt
+import bcrypt  # type: ignore[import]
 import pymacaroons
-from canonicaljson import json
-
-from twisted.internet import defer
-from twisted.web.client import PartialDownloadError
 
 import synapse.util.stringutils as stringutils
 from synapse.api.constants import LoginType
@@ -38,11 +36,15 @@ from synapse.api.errors import (
     UserDeactivatedError,
 )
 from synapse.api.ratelimiting import Ratelimiter
-from synapse.config.emailconfig import ThreepidBehaviour
+from synapse.handlers.ui_auth import INTERACTIVE_AUTH_CHECKERS
+from synapse.handlers.ui_auth.checkers import UserInteractiveAuthChecker
+from synapse.http.server import finish_request
+from synapse.http.site import SynapseRequest
 from synapse.logging.context import defer_to_thread
+from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.module_api import ModuleApi
-from synapse.types import UserID
-from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.push.mailer import load_jinja2_templates
+from synapse.types import Requester, UserID
 
 from ._base import BaseHandler
 
@@ -58,23 +60,14 @@ class AuthHandler(BaseHandler):
             hs (synapse.server.HomeServer):
         """
         super(AuthHandler, self).__init__(hs)
-        self.checkers = {
-            LoginType.RECAPTCHA: self._check_recaptcha,
-            LoginType.EMAIL_IDENTITY: self._check_email_identity,
-            LoginType.MSISDN: self._check_msisdn,
-            LoginType.DUMMY: self._check_dummy_auth,
-            LoginType.TERMS: self._check_terms_auth,
-        }
-        self.bcrypt_rounds = hs.config.bcrypt_rounds
 
-        # This is not a cache per se, but a store of all current sessions that
-        # expire after N hours
-        self.sessions = ExpiringCache(
-            cache_name="register_sessions",
-            clock=hs.get_clock(),
-            expiry_ms=self.SESSION_EXPIRE_MS,
-            reset_expiry_on_get=True,
-        )
+        self.checkers = {}  # type: Dict[str, UserInteractiveAuthChecker]
+        for auth_checker_class in INTERACTIVE_AUTH_CHECKERS:
+            inst = auth_checker_class(hs)
+            if inst.is_enabled():
+                self.checkers[inst.AUTH_TYPE] = inst  # type: ignore
+
+        self.bcrypt_rounds = hs.config.bcrypt_rounds
 
         account_handler = ModuleApi(hs, self)
         self.password_providers = [
@@ -87,6 +80,9 @@ class AuthHandler(BaseHandler):
         self.hs = hs  # FIXME better possibility to access registrationHandler later?
         self.macaroon_gen = hs.get_macaroon_generator()
         self._password_enabled = hs.config.password_enabled
+        self._sso_enabled = (
+            hs.config.cas_enabled or hs.config.saml2_enabled or hs.config.oidc_enabled
+        )
 
         # we keep this as a list despite the O(N^2) implication so that we can
         # keep PASSWORD first and avoid confusing clients which pick the first
@@ -102,14 +98,70 @@ class AuthHandler(BaseHandler):
                     if t not in login_types:
                         login_types.append(t)
         self._supported_login_types = login_types
-
-        self._account_ratelimiter = Ratelimiter()
-        self._failed_attempts_ratelimiter = Ratelimiter()
+        # Login types and UI Auth types have a heavy overlap, but are not
+        # necessarily identical. Login types have SSO (and other login types)
+        # added in the rest layer, see synapse.rest.client.v1.login.LoginRestServerlet.on_GET.
+        ui_auth_types = login_types.copy()
+        if self._sso_enabled:
+            ui_auth_types.append(LoginType.SSO)
+        self._supported_ui_auth_types = ui_auth_types
+
+        # Ratelimiter for failed auth during UIA. Uses same ratelimit config
+        # as per `rc_login.failed_attempts`.
+        self._failed_uia_attempts_ratelimiter = Ratelimiter(
+            clock=self.clock,
+            rate_hz=self.hs.config.rc_login_failed_attempts.per_second,
+            burst_count=self.hs.config.rc_login_failed_attempts.burst_count,
+        )
 
         self._clock = self.hs.get_clock()
 
-    @defer.inlineCallbacks
-    def validate_user_via_ui_auth(self, requester, request_body, clientip):
+        # Expire old UI auth sessions after a period of time.
+        if hs.config.worker_app is None:
+            self._clock.looping_call(
+                run_as_background_process,
+                5 * 60 * 1000,
+                "expire_old_sessions",
+                self._expire_old_sessions,
+            )
+
+        # Load the SSO HTML templates.
+
+        # The following template is shown to the user during a client login via SSO,
+        # after the SSO completes and before redirecting them back to their client.
+        # It notifies the user they are about to give access to their matrix account
+        # to the client.
+        self._sso_redirect_confirm_template = load_jinja2_templates(
+            hs.config.sso_template_dir, ["sso_redirect_confirm.html"],
+        )[0]
+        # The following template is shown during user interactive authentication
+        # in the fallback auth scenario. It notifies the user that they are
+        # authenticating for an operation to occur on their account.
+        self._sso_auth_confirm_template = load_jinja2_templates(
+            hs.config.sso_template_dir, ["sso_auth_confirm.html"],
+        )[0]
+        # The following template is shown after a successful user interactive
+        # authentication session. It tells the user they can close the window.
+        self._sso_auth_success_template = hs.config.sso_auth_success_template
+        # The following template is shown during the SSO authentication process if
+        # the account is deactivated.
+        self._sso_account_deactivated_template = (
+            hs.config.sso_account_deactivated_template
+        )
+
+        self._server_name = hs.config.server_name
+
+        # cast to tuple for use with str.startswith
+        self._whitelisted_sso_clients = tuple(hs.config.sso_client_whitelist)
+
+    async def validate_user_via_ui_auth(
+        self,
+        requester: Requester,
+        request: SynapseRequest,
+        request_body: Dict[str, Any],
+        clientip: str,
+        description: str,
+    ) -> dict:
         """
         Checks that the user is who they claim to be, via a UI auth.
 
@@ -118,14 +170,19 @@ class AuthHandler(BaseHandler):
         that it isn't stolen by re-authenticating them.
 
         Args:
-            requester (Requester): The user, as given by the access token
+            requester: The user, as given by the access token
+
+            request: The request sent by the client.
 
-            request_body (dict): The body of the request sent by the client
+            request_body: The body of the request sent by the client
 
-            clientip (str): The IP address of the client.
+            clientip: The IP address of the client.
+
+            description: A human readable string to be displayed to the user that
+                         describes the operation happening on their account.
 
         Returns:
-            defer.Deferred[dict]: the parameters for this request (which may
+            The parameters for this request (which may
                 have been given only in a previous call).
 
         Raises:
@@ -134,15 +191,31 @@ class AuthHandler(BaseHandler):
 
             AuthError if the client has completed a login flow, and it gives
                 a different user to `requester`
+
+            LimitExceededError if the ratelimiter's failed request count for this
+                user is too high to proceed
+
         """
 
+        user_id = requester.user.to_string()
+
+        # Check if we should be ratelimited due to too many previous failed attempts
+        self._failed_uia_attempts_ratelimiter.ratelimit(user_id, update=False)
+
         # build a list of supported flows
-        flows = [[login_type] for login_type in self._supported_login_types]
+        flows = [[login_type] for login_type in self._supported_ui_auth_types]
 
-        result, params, _ = yield self.check_auth(flows, request_body, clientip)
+        try:
+            result, params, _ = await self.check_auth(
+                flows, request, request_body, clientip, description
+            )
+        except LoginError:
+            # Update the ratelimiter to say we failed (`can_do_action` doesn't raise).
+            self._failed_uia_attempts_ratelimiter.can_do_action(user_id)
+            raise
 
         # find the completed login type
-        for login_type in self._supported_login_types:
+        for login_type in self._supported_ui_auth_types:
             if login_type not in result:
                 continue
 
@@ -158,34 +231,48 @@ class AuthHandler(BaseHandler):
 
         return params
 
-    @defer.inlineCallbacks
-    def check_auth(self, flows, clientdict, clientip):
+    def get_enabled_auth_types(self):
+        """Return the enabled user-interactive authentication types
+
+        Returns the UI-Auth types which are supported by the homeserver's current
+        config.
+        """
+        return self.checkers.keys()
+
+    async def check_auth(
+        self,
+        flows: List[List[str]],
+        request: SynapseRequest,
+        clientdict: Dict[str, Any],
+        clientip: str,
+        description: str,
+    ) -> Tuple[dict, dict, str]:
         """
         Takes a dictionary sent by the client in the login / registration
         protocol and handles the User-Interactive Auth flow.
 
-        As a side effect, this function fills in the 'creds' key on the user's
-        session with a map, which maps each auth-type (str) to the relevant
-        identity authenticated by that auth-type (mostly str, but for captcha, bool).
-
         If no auth flows have been completed successfully, raises an
         InteractiveAuthIncompleteError. To handle this, you can use
         synapse.rest.client.v2_alpha._base.interactive_auth_handler as a
         decorator.
 
         Args:
-            flows (list): A list of login flows. Each flow is an ordered list of
-                          strings representing auth-types. At least one full
-                          flow must be completed in order for auth to be successful.
+            flows: A list of login flows. Each flow is an ordered list of
+                   strings representing auth-types. At least one full
+                   flow must be completed in order for auth to be successful.
+
+            request: The request sent by the client.
 
             clientdict: The dictionary from the client root level, not the
                         'auth' key: this method prompts for auth if none is sent.
 
-            clientip (str): The IP address of the client.
+            clientip: The IP address of the client.
+
+            description: A human readable string to be displayed to the user that
+                         describes the operation happening on their account.
 
         Returns:
-            defer.Deferred[dict, dict, str]: a deferred tuple of
-                (creds, params, session_id).
+            A tuple of (creds, params, session_id).
 
                 'creds' contains the authenticated credentials of each stage.
 
@@ -201,47 +288,93 @@ class AuthHandler(BaseHandler):
         """
 
         authdict = None
-        sid = None
+        sid = None  # type: Optional[str]
         if clientdict and "auth" in clientdict:
             authdict = clientdict["auth"]
             del clientdict["auth"]
             if "session" in authdict:
                 sid = authdict["session"]
-        session = self._get_session_info(sid)
 
-        if len(clientdict) > 0:
+        # Convert the URI and method to strings.
+        uri = request.uri.decode("utf-8")
+        method = request.uri.decode("utf-8")
+
+        # If there's no session ID, create a new session.
+        if not sid:
+            session = await self.store.create_ui_auth_session(
+                clientdict, uri, method, description
+            )
+
+        else:
+            try:
+                session = await self.store.get_ui_auth_session(sid)
+            except StoreError:
+                raise SynapseError(400, "Unknown session ID: %s" % (sid,))
+
+            # If the client provides parameters, update what is persisted,
+            # otherwise use whatever was last provided.
+            #
             # This was designed to allow the client to omit the parameters
             # and just supply the session in subsequent calls so it split
             # auth between devices by just sharing the session, (eg. so you
             # could continue registration from your phone having clicked the
             # email auth link on there). It's probably too open to abuse
             # because it lets unauthenticated clients store arbitrary objects
-            # on a home server.
-            # Revisit: Assumimg the REST APIs do sensible validation, the data
-            # isn't arbintrary.
-            session["clientdict"] = clientdict
-            self._save_session(session)
-        elif "clientdict" in session:
-            clientdict = session["clientdict"]
+            # on a homeserver.
+            #
+            # Revisit: Assuming the REST APIs do sensible validation, the data
+            # isn't arbitrary.
+            #
+            # Note that the registration endpoint explicitly removes the
+            # "initial_device_display_name" parameter if it is provided
+            # without a "password" parameter. See the changes to
+            # synapse.rest.client.v2_alpha.register.RegisterRestServlet.on_POST
+            # in commit 544722bad23fc31056b9240189c3cbbbf0ffd3f9.
+            if not clientdict:
+                clientdict = session.clientdict
+
+            # Ensure that the queried operation does not vary between stages of
+            # the UI authentication session. This is done by generating a stable
+            # comparator and storing it during the initial query. Subsequent
+            # queries ensure that this comparator has not changed.
+            #
+            # The comparator is based on the requested URI and HTTP method. The
+            # client dict (minus the auth dict) should also be checked, but some
+            # clients are not spec compliant, just warn for now if the client
+            # dict changes.
+            if (session.uri, session.method) != (uri, method):
+                raise SynapseError(
+                    403,
+                    "Requested operation has changed during the UI authentication session.",
+                )
+
+            if session.clientdict != clientdict:
+                logger.warning(
+                    "Requested operation has changed during the UI "
+                    "authentication session. A future version of Synapse "
+                    "will remove this capability."
+                )
+
+            # For backwards compatibility, changes to the client dict are
+            # persisted as clients modify them throughout their user interactive
+            # authentication flow.
+            await self.store.set_ui_auth_clientdict(sid, clientdict)
 
         if not authdict:
             raise InteractiveAuthIncompleteError(
-                self._auth_dict_for_flows(flows, session)
+                self._auth_dict_for_flows(flows, session.session_id)
             )
 
-        if "creds" not in session:
-            session["creds"] = {}
-        creds = session["creds"]
-
         # check auth type currently being presented
-        errordict = {}
+        errordict = {}  # type: Dict[str, Any]
         if "type" in authdict:
-            login_type = authdict["type"]
+            login_type = authdict["type"]  # type: str
             try:
-                result = yield self._check_auth_dict(authdict, clientip)
+                result = await self._check_auth_dict(authdict, clientip)
                 if result:
-                    creds[login_type] = result
-                    self._save_session(session)
+                    await self.store.mark_ui_auth_stage_complete(
+                        session.session_id, login_type, result
+                    )
             except LoginError as e:
                 if login_type == LoginType.EMAIL_IDENTITY:
                     # riot used to have a bug where it would request a new
@@ -257,6 +390,7 @@ class AuthHandler(BaseHandler):
                 # so that the client can have another go.
                 errordict = e.error_dict()
 
+        creds = await self.store.get_completed_ui_auth_stages(session.session_id)
         for f in flows:
             if len(set(f) - set(creds)) == 0:
                 # it's very useful to know what args are stored, but this can
@@ -269,15 +403,17 @@ class AuthHandler(BaseHandler):
                     creds,
                     list(clientdict),
                 )
-                return creds, clientdict, session["id"]
 
-        ret = self._auth_dict_for_flows(flows, session)
+                return creds, clientdict, session.session_id
+
+        ret = self._auth_dict_for_flows(flows, session.session_id)
         ret["completed"] = list(creds)
         ret.update(errordict)
         raise InteractiveAuthIncompleteError(ret)
 
-    @defer.inlineCallbacks
-    def add_oob_auth(self, stagetype, authdict, clientip):
+    async def add_oob_auth(
+        self, stagetype: str, authdict: Dict[str, Any], clientip: str
+    ) -> bool:
         """
         Adds the result of out-of-band authentication into an existing auth
         session. Currently used for adding the result of fallback auth.
@@ -287,19 +423,15 @@ class AuthHandler(BaseHandler):
         if "session" not in authdict:
             raise LoginError(400, "", Codes.MISSING_PARAM)
 
-        sess = self._get_session_info(authdict["session"])
-        if "creds" not in sess:
-            sess["creds"] = {}
-        creds = sess["creds"]
-
-        result = yield self.checkers[stagetype](authdict, clientip)
+        result = await self.checkers[stagetype].check_auth(authdict, clientip)
         if result:
-            creds[stagetype] = result
-            self._save_session(sess)
+            await self.store.mark_ui_auth_stage_complete(
+                authdict["session"], stagetype, result
+            )
             return True
         return False
 
-    def get_session_id(self, clientdict):
+    def get_session_id(self, clientdict: Dict[str, Any]) -> Optional[str]:
         """
         Gets the session ID for a client given the client dictionary
 
@@ -307,7 +439,7 @@ class AuthHandler(BaseHandler):
             clientdict: The dictionary sent by the client in the request
 
         Returns:
-            str|None: The string session ID the client sent. If the client did
+            The string session ID the client sent. If the client did
                 not send a session ID, returns None.
         """
         sid = None
@@ -317,43 +449,57 @@ class AuthHandler(BaseHandler):
                 sid = authdict["session"]
         return sid
 
-    def set_session_data(self, session_id, key, value):
+    async def set_session_data(self, session_id: str, key: str, value: Any) -> None:
         """
         Store a key-value pair into the sessions data associated with this
         request. This data is stored server-side and cannot be modified by
         the client.
 
         Args:
-            session_id (string): The ID of this session as returned from check_auth
-            key (string): The key to store the data under
-            value (any): The data to store
+            session_id: The ID of this session as returned from check_auth
+            key: The key to store the data under
+            value: The data to store
         """
-        sess = self._get_session_info(session_id)
-        sess.setdefault("serverdict", {})[key] = value
-        self._save_session(sess)
+        try:
+            await self.store.set_ui_auth_session_data(session_id, key, value)
+        except StoreError:
+            raise SynapseError(400, "Unknown session ID: %s" % (session_id,))
 
-    def get_session_data(self, session_id, key, default=None):
+    async def get_session_data(
+        self, session_id: str, key: str, default: Optional[Any] = None
+    ) -> Any:
         """
         Retrieve data stored with set_session_data
 
         Args:
-            session_id (string): The ID of this session as returned from check_auth
-            key (string): The key to store the data under
-            default (any): Value to return if the key has not been set
+            session_id: The ID of this session as returned from check_auth
+            key: The key to store the data under
+            default: Value to return if the key has not been set
         """
-        sess = self._get_session_info(session_id)
-        return sess.setdefault("serverdict", {}).get(key, default)
+        try:
+            return await self.store.get_ui_auth_session_data(session_id, key, default)
+        except StoreError:
+            raise SynapseError(400, "Unknown session ID: %s" % (session_id,))
 
-    @defer.inlineCallbacks
-    def _check_auth_dict(self, authdict, clientip):
+    async def _expire_old_sessions(self):
+        """
+        Invalidate any user interactive authentication sessions that have expired.
+        """
+        now = self._clock.time_msec()
+        expiration_time = now - self.SESSION_EXPIRE_MS
+        await self.store.delete_old_ui_auth_sessions(expiration_time)
+
+    async def _check_auth_dict(
+        self, authdict: Dict[str, Any], clientip: str
+    ) -> Union[Dict[str, Any], str]:
         """Attempt to validate the auth dict provided by a client
 
         Args:
-            authdict (object): auth dict provided by the client
-            clientip (str): IP address of the client
+            authdict: auth dict provided by the client
+            clientip: IP address of the client
 
         Returns:
-            Deferred: result of the stage verification.
+            Result of the stage verification.
 
         Raises:
             StoreError if there was a problem accessing the database
@@ -363,7 +509,7 @@ class AuthHandler(BaseHandler):
         login_type = authdict["type"]
         checker = self.checkers.get(login_type)
         if checker is not None:
-            res = yield checker(authdict, clientip=clientip)
+            res = await checker.check_auth(authdict, clientip=clientip)
             return res
 
         # build a v1-login-style dict out of the authdict and fall back to the
@@ -373,132 +519,13 @@ class AuthHandler(BaseHandler):
         if user_id is None:
             raise SynapseError(400, "", Codes.MISSING_PARAM)
 
-        (canonical_id, callback) = yield self.validate_login(user_id, authdict)
+        (canonical_id, callback) = await self.validate_login(user_id, authdict)
         return canonical_id
 
-    @defer.inlineCallbacks
-    def _check_recaptcha(self, authdict, clientip, **kwargs):
-        try:
-            user_response = authdict["response"]
-        except KeyError:
-            # Client tried to provide captcha but didn't give the parameter:
-            # bad request.
-            raise LoginError(
-                400, "Captcha response is required", errcode=Codes.CAPTCHA_NEEDED
-            )
-
-        logger.info(
-            "Submitting recaptcha response %s with remoteip %s", user_response, clientip
-        )
-
-        # TODO: get this from the homeserver rather than creating a new one for
-        # each request
-        try:
-            client = self.hs.get_simple_http_client()
-            resp_body = yield client.post_urlencoded_get_json(
-                self.hs.config.recaptcha_siteverify_api,
-                args={
-                    "secret": self.hs.config.recaptcha_private_key,
-                    "response": user_response,
-                    "remoteip": clientip,
-                },
-            )
-        except PartialDownloadError as pde:
-            # Twisted is silly
-            data = pde.response
-            resp_body = json.loads(data)
-
-        if "success" in resp_body:
-            # Note that we do NOT check the hostname here: we explicitly
-            # intend the CAPTCHA to be presented by whatever client the
-            # user is using, we just care that they have completed a CAPTCHA.
-            logger.info(
-                "%s reCAPTCHA from hostname %s",
-                "Successful" if resp_body["success"] else "Failed",
-                resp_body.get("hostname"),
-            )
-            if resp_body["success"]:
-                return True
-        raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)
-
-    def _check_email_identity(self, authdict, **kwargs):
-        return self._check_threepid("email", authdict, **kwargs)
-
-    def _check_msisdn(self, authdict, **kwargs):
-        return self._check_threepid("msisdn", authdict)
-
-    def _check_dummy_auth(self, authdict, **kwargs):
-        return defer.succeed(True)
-
-    def _check_terms_auth(self, authdict, **kwargs):
-        return defer.succeed(True)
-
-    @defer.inlineCallbacks
-    def _check_threepid(self, medium, authdict, **kwargs):
-        if "threepid_creds" not in authdict:
-            raise LoginError(400, "Missing threepid_creds", Codes.MISSING_PARAM)
-
-        threepid_creds = authdict["threepid_creds"]
-
-        identity_handler = self.hs.get_handlers().identity_handler
-
-        logger.info("Getting validated threepid. threepidcreds: %r", (threepid_creds,))
-        if self.hs.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
-            if medium == "email":
-                threepid = yield identity_handler.threepid_from_creds(
-                    self.hs.config.account_threepid_delegate_email, threepid_creds
-                )
-            elif medium == "msisdn":
-                threepid = yield identity_handler.threepid_from_creds(
-                    self.hs.config.account_threepid_delegate_msisdn, threepid_creds
-                )
-            else:
-                raise SynapseError(400, "Unrecognized threepid medium: %s" % (medium,))
-        elif self.hs.config.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
-            row = yield self.store.get_threepid_validation_session(
-                medium,
-                threepid_creds["client_secret"],
-                sid=threepid_creds["sid"],
-                validated=True,
-            )
-
-            threepid = (
-                {
-                    "medium": row["medium"],
-                    "address": row["address"],
-                    "validated_at": row["validated_at"],
-                }
-                if row
-                else None
-            )
-
-            if row:
-                # Valid threepid returned, delete from the db
-                yield self.store.delete_threepid_session(threepid_creds["sid"])
-        else:
-            raise SynapseError(
-                400, "Password resets are not enabled on this homeserver"
-            )
-
-        if not threepid:
-            raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)
-
-        if threepid["medium"] != medium:
-            raise LoginError(
-                401,
-                "Expecting threepid of type '%s', got '%s'"
-                % (medium, threepid["medium"]),
-                errcode=Codes.UNAUTHORIZED,
-            )
-
-        threepid["threepid_creds"] = authdict["threepid_creds"]
-
-        return threepid
-
-    def _get_params_recaptcha(self):
+    def _get_params_recaptcha(self) -> dict:
         return {"public_key": self.hs.config.recaptcha_public_key}
 
-    def _get_params_terms(self):
+    def _get_params_terms(self) -> dict:
         return {
             "policies": {
                 "privacy_policy": {
@@ -515,7 +542,9 @@ class AuthHandler(BaseHandler):
             }
         }
 
-    def _auth_dict_for_flows(self, flows, session):
+    def _auth_dict_for_flows(
+        self, flows: List[List[str]], session_id: str,
+    ) -> Dict[str, Any]:
         public_flows = []
         for f in flows:
             public_flows.append(f)
@@ -525,7 +554,7 @@ class AuthHandler(BaseHandler):
             LoginType.TERMS: self._get_params_terms,
         }
 
-        params = {}
+        params = {}  # type: Dict[str, Any]
 
         for f in public_flows:
             for stage in f:
@@ -533,25 +562,14 @@ class AuthHandler(BaseHandler):
                     params[stage] = get_params[stage]()
 
         return {
-            "session": session["id"],
+            "session": session_id,
             "flows": [{"stages": f} for f in public_flows],
             "params": params,
         }
 
-    def _get_session_info(self, session_id):
-        if session_id not in self.sessions:
-            session_id = None
-
-        if not session_id:
-            # create a new session
-            while session_id is None or session_id in self.sessions:
-                session_id = stringutils.random_string(24)
-            self.sessions[session_id] = {"id": session_id}
-
-        return self.sessions[session_id]
-
-    @defer.inlineCallbacks
-    def get_access_token_for_user_id(self, user_id, device_id, valid_until_ms):
+    async def get_access_token_for_user_id(
+        self, user_id: str, device_id: Optional[str], valid_until_ms: Optional[int]
+    ):
         """
         Creates a new access token for the user with the given user ID.
 
@@ -561,11 +579,11 @@ class AuthHandler(BaseHandler):
         The device will be recorded in the table if it is not there already.
 
         Args:
-            user_id (str): canonical User ID
-            device_id (str|None): the device ID to associate with the tokens.
+            user_id: canonical User ID
+            device_id: the device ID to associate with the tokens.
                None to leave the tokens unassociated with a device (deprecated:
                we should always have a device ID)
-            valid_until_ms (int|None): when the token is valid until. None for
+            valid_until_ms: when the token is valid until. None for
                 no expiry.
         Returns:
               The access token for the user's session.
@@ -579,10 +597,10 @@ class AuthHandler(BaseHandler):
             )
         logger.info("Logging in user %s on device %s%s", user_id, device_id, fmt_expiry)
 
-        yield self.auth.check_auth_blocking(user_id)
+        await self.auth.check_auth_blocking(user_id)
 
         access_token = self.macaroon_gen.generate_access_token(user_id)
-        yield self.store.add_access_token_to_user(
+        await self.store.add_access_token_to_user(
             user_id, access_token, device_id, valid_until_ms
         )
 
@@ -592,52 +610,45 @@ class AuthHandler(BaseHandler):
         # device, so we double-check it here.
         if device_id is not None:
             try:
-                yield self.store.get_device(user_id, device_id)
+                await self.store.get_device(user_id, device_id)
             except StoreError:
-                yield self.store.delete_access_token(access_token)
+                await self.store.delete_access_token(access_token)
                 raise StoreError(400, "Login raced against device deletion")
 
         return access_token
 
-    @defer.inlineCallbacks
-    def check_user_exists(self, user_id):
+    async def check_user_exists(self, user_id: str) -> Optional[str]:
         """
         Checks to see if a user with the given id exists. Will check case
         insensitively, but return None if there are multiple inexact matches.
 
         Args:
-            (unicode|bytes) user_id: complete @user:id
+            user_id: complete @user:id
 
         Returns:
-            defer.Deferred: (unicode) canonical_user_id, or None if zero or
-            multiple matches
-
-        Raises:
-            LimitExceededError if the ratelimiter's login requests count for this
-                user is too high too proceed.
-            UserDeactivatedError if a user is found but is deactivated.
+            The canonical_user_id, or None if zero or multiple matches
         """
-        self.ratelimit_login_per_account(user_id)
-        res = yield self._find_user_id_and_pwd_hash(user_id)
+        res = await self._find_user_id_and_pwd_hash(user_id)
         if res is not None:
             return res[0]
         return None
 
-    @defer.inlineCallbacks
-    def _find_user_id_and_pwd_hash(self, user_id):
+    async def _find_user_id_and_pwd_hash(
+        self, user_id: str
+    ) -> Optional[Tuple[str, str]]:
         """Checks to see if a user with the given id exists. Will check case
         insensitively, but will return None if there are multiple inexact
         matches.
 
         Returns:
-            tuple: A 2-tuple of `(canonical_user_id, password_hash)`
-            None: if there is not exactly one match
+            A 2-tuple of `(canonical_user_id, password_hash)` or `None`
+            if there is not exactly one match
         """
-        user_infos = yield self.store.get_users_by_id_case_insensitive(user_id)
+        user_infos = await self.store.get_users_by_id_case_insensitive(user_id)
 
         result = None
         if not user_infos:
-            logger.warn("Attempted to login as %s but they do not exist", user_id)
+            logger.warning("Attempted to login as %s but they do not exist", user_id)
         elif len(user_infos) == 1:
             # a single match (possibly not exact)
             result = user_infos.popitem()
@@ -646,7 +657,7 @@ class AuthHandler(BaseHandler):
             result = (user_id, user_infos[user_id])
         else:
             # multiple matches, none of them exact
-            logger.warn(
+            logger.warning(
                 "Attempted to login as %s but it matches more than one user "
                 "inexactly: %r",
                 user_id,
@@ -654,7 +665,7 @@ class AuthHandler(BaseHandler):
             )
         return result
 
-    def get_supported_login_types(self):
+    def get_supported_login_types(self) -> Iterable[str]:
         """Get a the login types supported for the /login API
 
         By default this is just 'm.login.password' (unless password_enabled is
@@ -662,30 +673,29 @@ class AuthHandler(BaseHandler):
         other login types.
 
         Returns:
-            Iterable[str]: login types
+            login types
         """
         return self._supported_login_types
 
-    @defer.inlineCallbacks
-    def validate_login(self, username, login_submission):
+    async def validate_login(
+        self, username: str, login_submission: Dict[str, Any]
+    ) -> Tuple[str, Optional[Callable[[Dict[str, str]], None]]]:
         """Authenticates the user for the /login API
 
         Also used by the user-interactive auth flow to validate
         m.login.password auth types.
 
         Args:
-            username (str): username supplied by the user
-            login_submission (dict): the whole of the login submission
+            username: username supplied by the user
+            login_submission: the whole of the login submission
                 (including 'type' and other relevant fields)
         Returns:
-            Deferred[str, func]: canonical user id, and optional callback
+            A tuple of the canonical user id, and optional callback
                 to be called once the access token and device id are issued
         Raises:
             StoreError if there was a problem accessing the database
             SynapseError if there was a problem with the request
             LoginError if there was an authentication problem.
-            LimitExceededError if the ratelimiter's login requests count for this
-                user is too high too proceed.
         """
 
         if username.startswith("@"):
@@ -693,8 +703,6 @@ class AuthHandler(BaseHandler):
         else:
             qualified_user_id = UserID(username, self.hs.hostname).to_string()
 
-        self.ratelimit_login_per_account(qualified_user_id)
-
         login_type = login_submission.get("type")
         known_login_type = False
 
@@ -711,7 +719,7 @@ class AuthHandler(BaseHandler):
         for provider in self.password_providers:
             if hasattr(provider, "check_password") and login_type == LoginType.PASSWORD:
                 known_login_type = True
-                is_valid = yield provider.check_password(qualified_user_id, password)
+                is_valid = await provider.check_password(qualified_user_id, password)
                 if is_valid:
                     return qualified_user_id, None
 
@@ -743,7 +751,7 @@ class AuthHandler(BaseHandler):
                     % (login_type, missing_fields),
                 )
 
-            result = yield provider.check_auth(username, login_type, login_dict)
+            result = await provider.check_auth(username, login_type, login_dict)
             if result:
                 if isinstance(result, str):
                     result = (result, None)
@@ -752,8 +760,8 @@ class AuthHandler(BaseHandler):
         if login_type == LoginType.PASSWORD and self.hs.config.password_localdb_enabled:
             known_login_type = True
 
-            canonical_user_id = yield self._check_local_password(
-                qualified_user_id, password
+            canonical_user_id = await self._check_local_password(
+                qualified_user_id, password  # type: ignore
             )
 
             if canonical_user_id:
@@ -762,32 +770,23 @@ class AuthHandler(BaseHandler):
         if not known_login_type:
             raise SynapseError(400, "Unknown login type %s" % login_type)
 
-        # unknown username or invalid password.
-        self._failed_attempts_ratelimiter.ratelimit(
-            qualified_user_id.lower(),
-            time_now_s=self._clock.time(),
-            rate_hz=self.hs.config.rc_login_failed_attempts.per_second,
-            burst_count=self.hs.config.rc_login_failed_attempts.burst_count,
-            update=True,
-        )
-
         # We raise a 403 here, but note that if we're doing user-interactive
         # login, it turns all LoginErrors into a 401 anyway.
         raise LoginError(403, "Invalid password", errcode=Codes.FORBIDDEN)
 
-    @defer.inlineCallbacks
-    def check_password_provider_3pid(self, medium, address, password):
+    async def check_password_provider_3pid(
+        self, medium: str, address: str, password: str
+    ) -> Tuple[Optional[str], Optional[Callable[[Dict[str, str]], None]]]:
         """Check if a password provider is able to validate a thirdparty login
 
         Args:
-            medium (str): The medium of the 3pid (ex. email).
-            address (str): The address of the 3pid (ex. jdoe@example.com).
-            password (str): The password of the user.
+            medium: The medium of the 3pid (ex. email).
+            address: The address of the 3pid (ex. jdoe@example.com).
+            password: The password of the user.
 
         Returns:
-            Deferred[(str|None, func|None)]: A tuple of `(user_id,
-            callback)`. If authentication is successful, `user_id` is a `str`
-            containing the authenticated, canonical user ID. `callback` is
+            A tuple of `(user_id, callback)`. If authentication is successful,
+            `user_id`is the authenticated, canonical user ID. `callback` is
             then either a function to be later run after the server has
             completed login/registration, or `None`. If authentication was
             unsuccessful, `user_id` and `callback` are both `None`.
@@ -799,7 +798,7 @@ class AuthHandler(BaseHandler):
                 # success, to a str (which is the user_id) or a tuple of
                 # (user_id, callback_func), where callback_func should be run
                 # after we've finished everything else
-                result = yield provider.check_3pid_auth(medium, address, password)
+                result = await provider.check_3pid_auth(medium, address, password)
                 if result:
                     # Check if the return value is a str or a tuple
                     if isinstance(result, str):
@@ -809,43 +808,36 @@ class AuthHandler(BaseHandler):
 
         return None, None
 
-    @defer.inlineCallbacks
-    def _check_local_password(self, user_id, password):
+    async def _check_local_password(self, user_id: str, password: str) -> Optional[str]:
         """Authenticate a user against the local password database.
 
         user_id is checked case insensitively, but will return None if there are
         multiple inexact matches.
 
         Args:
-            user_id (unicode): complete @user:id
-            password (unicode): the provided password
+            user_id: complete @user:id
+            password: the provided password
         Returns:
-            Deferred[unicode] the canonical_user_id, or Deferred[None] if
-                unknown user/bad password
-
-        Raises:
-            LimitExceededError if the ratelimiter's login requests count for this
-                user is too high too proceed.
+            The canonical_user_id, or None if unknown user/bad password
         """
-        lookupres = yield self._find_user_id_and_pwd_hash(user_id)
+        lookupres = await self._find_user_id_and_pwd_hash(user_id)
         if not lookupres:
             return None
         (user_id, password_hash) = lookupres
 
         # If the password hash is None, the account has likely been deactivated
         if not password_hash:
-            deactivated = yield self.store.get_user_deactivated_status(user_id)
+            deactivated = await self.store.get_user_deactivated_status(user_id)
             if deactivated:
                 raise UserDeactivatedError("This account has been deactivated")
 
-        result = yield self.validate_hash(password, password_hash)
+        result = await self.validate_hash(password, password_hash)
         if not result:
-            logger.warn("Failed password login for user %s", user_id)
+            logger.warning("Failed password login for user %s", user_id)
             return None
         return user_id
 
-    @defer.inlineCallbacks
-    def validate_short_term_login_token_and_get_user_id(self, login_token):
+    async def validate_short_term_login_token_and_get_user_id(self, login_token: str):
         auth_api = self.hs.get_auth()
         user_id = None
         try:
@@ -854,27 +846,24 @@ class AuthHandler(BaseHandler):
             auth_api.validate_macaroon(macaroon, "login", user_id)
         except Exception:
             raise AuthError(403, "Invalid token", errcode=Codes.FORBIDDEN)
-        self.ratelimit_login_per_account(user_id)
-        yield self.auth.check_auth_blocking(user_id)
+
+        await self.auth.check_auth_blocking(user_id)
         return user_id
 
-    @defer.inlineCallbacks
-    def delete_access_token(self, access_token):
+    async def delete_access_token(self, access_token: str):
         """Invalidate a single access token
 
         Args:
-            access_token (str): access token to be deleted
+            access_token: access token to be deleted
 
-        Returns:
-            Deferred
         """
-        user_info = yield self.auth.get_user_by_access_token(access_token)
-        yield self.store.delete_access_token(access_token)
+        user_info = await self.auth.get_user_by_access_token(access_token)
+        await self.store.delete_access_token(access_token)
 
         # see if any of our auth providers want to know about this
         for provider in self.password_providers:
             if hasattr(provider, "on_logged_out"):
-                yield provider.on_logged_out(
+                await provider.on_logged_out(
                     user_id=str(user_info["user"]),
                     device_id=user_info["device_id"],
                     access_token=access_token,
@@ -882,27 +871,26 @@ class AuthHandler(BaseHandler):
 
         # delete pushers associated with this access token
         if user_info["token_id"] is not None:
-            yield self.hs.get_pusherpool().remove_pushers_by_access_token(
+            await self.hs.get_pusherpool().remove_pushers_by_access_token(
                 str(user_info["user"]), (user_info["token_id"],)
             )
 
-    @defer.inlineCallbacks
-    def delete_access_tokens_for_user(
-        self, user_id, except_token_id=None, device_id=None
+    async def delete_access_tokens_for_user(
+        self,
+        user_id: str,
+        except_token_id: Optional[str] = None,
+        device_id: Optional[str] = None,
     ):
         """Invalidate access tokens belonging to a user
 
         Args:
-            user_id (str):  ID of user the tokens belong to
-            except_token_id (str|None): access_token ID which should *not* be
-                deleted
-            device_id (str|None):  ID of device the tokens are associated with.
+            user_id:  ID of user the tokens belong to
+            except_token_id: access_token ID which should *not* be deleted
+            device_id:  ID of device the tokens are associated with.
                 If None, tokens associated with any device (or no device) will
                 be deleted
-        Returns:
-            Deferred
         """
-        tokens_and_devices = yield self.store.user_delete_access_tokens(
+        tokens_and_devices = await self.store.user_delete_access_tokens(
             user_id, except_token_id=except_token_id, device_id=device_id
         )
 
@@ -910,19 +898,28 @@ class AuthHandler(BaseHandler):
         for provider in self.password_providers:
             if hasattr(provider, "on_logged_out"):
                 for token, token_id, device_id in tokens_and_devices:
-                    yield provider.on_logged_out(
+                    await provider.on_logged_out(
                         user_id=user_id, device_id=device_id, access_token=token
                     )
 
         # delete pushers associated with the access tokens
-        yield self.hs.get_pusherpool().remove_pushers_by_access_token(
+        await self.hs.get_pusherpool().remove_pushers_by_access_token(
             user_id, (token_id for _, token_id, _ in tokens_and_devices)
         )
 
-    @defer.inlineCallbacks
-    def add_threepid(self, user_id, medium, address, validated_at):
+    async def add_threepid(
+        self, user_id: str, medium: str, address: str, validated_at: int
+    ):
+        # check if medium has a valid value
+        if medium not in ["email", "msisdn"]:
+            raise SynapseError(
+                code=400,
+                msg=("'%s' is not a valid value for 'medium'" % (medium,)),
+                errcode=Codes.INVALID_PARAM,
+            )
+
         # 'Canonicalise' email addresses down to lower case.
-        # We've now moving towards the Home Server being the entity that
+        # We've now moving towards the homeserver being the entity that
         # is responsible for validating threepids used for resetting passwords
         # on accounts, so in future Synapse will gain knowledge of specific
         # types (mediums) of threepid. For now, we still use the existing
@@ -933,26 +930,26 @@ class AuthHandler(BaseHandler):
         if medium == "email":
             address = address.lower()
 
-        yield self.store.user_add_threepid(
+        await self.store.user_add_threepid(
             user_id, medium, address, validated_at, self.hs.get_clock().time_msec()
         )
 
-    @defer.inlineCallbacks
-    def delete_threepid(self, user_id, medium, address, id_server=None):
+    async def delete_threepid(
+        self, user_id: str, medium: str, address: str, id_server: Optional[str] = None
+    ) -> bool:
         """Attempts to unbind the 3pid on the identity servers and deletes it
         from the local database.
 
         Args:
-            user_id (str)
-            medium (str)
-            address (str)
-            id_server (str|None): Use the given identity server when unbinding
+            user_id: ID of user to remove the 3pid from.
+            medium: The medium of the 3pid being removed: "email" or "msisdn".
+            address: The 3pid address to remove.
+            id_server: Use the given identity server when unbinding
                 any threepids. If None then will attempt to unbind using the
                 identity server specified when binding (if known).
 
-
         Returns:
-            Deferred[bool]: Returns True if successfully unbound the 3pid on
+            Returns True if successfully unbound the 3pid on
             the identity server, False if identity server doesn't support the
             unbind API.
         """
@@ -962,27 +959,21 @@ class AuthHandler(BaseHandler):
             address = address.lower()
 
         identity_handler = self.hs.get_handlers().identity_handler
-        result = yield identity_handler.try_unbind_threepid(
+        result = await identity_handler.try_unbind_threepid(
             user_id, {"medium": medium, "address": address, "id_server": id_server}
         )
 
-        yield self.store.user_delete_threepid(user_id, medium, address)
+        await self.store.user_delete_threepid(user_id, medium, address)
         return result
 
-    def _save_session(self, session):
-        # TODO: Persistent storage
-        logger.debug("Saving session %s", session)
-        session["last_used"] = self.hs.get_clock().time_msec()
-        self.sessions[session["id"]] = session
-
-    def hash(self, password):
+    async def hash(self, password: str) -> str:
         """Computes a secure hash of password.
 
         Args:
-            password (unicode): Password to hash.
+            password: Password to hash.
 
         Returns:
-            Deferred(unicode): Hashed password.
+            Hashed password.
         """
 
         def _do_hash():
@@ -994,17 +985,19 @@ class AuthHandler(BaseHandler):
                 bcrypt.gensalt(self.bcrypt_rounds),
             ).decode("ascii")
 
-        return defer_to_thread(self.hs.get_reactor(), _do_hash)
+        return await defer_to_thread(self.hs.get_reactor(), _do_hash)
 
-    def validate_hash(self, password, stored_hash):
+    async def validate_hash(
+        self, password: str, stored_hash: Union[bytes, str]
+    ) -> bool:
         """Validates that self.hash(password) == stored_hash.
 
         Args:
-            password (unicode): Password to hash.
-            stored_hash (bytes): Expected hash value.
+            password: Password to hash.
+            stored_hash: Expected hash value.
 
         Returns:
-            Deferred(bool): Whether self.hash(password) == stored_hash.
+            Whether self.hash(password) == stored_hash.
         """
 
         def _do_validate_hash():
@@ -1020,46 +1013,150 @@ class AuthHandler(BaseHandler):
             if not isinstance(stored_hash, bytes):
                 stored_hash = stored_hash.encode("ascii")
 
-            return defer_to_thread(self.hs.get_reactor(), _do_validate_hash)
+            return await defer_to_thread(self.hs.get_reactor(), _do_validate_hash)
         else:
-            return defer.succeed(False)
+            return False
 
-    def ratelimit_login_per_account(self, user_id):
-        """Checks whether the process must be stopped because of ratelimiting.
+    async def start_sso_ui_auth(self, redirect_url: str, session_id: str) -> str:
+        """
+        Get the HTML for the SSO redirect confirmation page.
+
+        Args:
+            redirect_url: The URL to redirect to the SSO provider.
+            session_id: The user interactive authentication session ID.
 
-        Checks against two ratelimiters: the generic one for login attempts per
-        account and the one specific to failed attempts.
+        Returns:
+            The HTML to render.
+        """
+        try:
+            session = await self.store.get_ui_auth_session(session_id)
+        except StoreError:
+            raise SynapseError(400, "Unknown session ID: %s" % (session_id,))
+        return self._sso_auth_confirm_template.render(
+            description=session.description, redirect_url=redirect_url,
+        )
+
+    async def complete_sso_ui_auth(
+        self, registered_user_id: str, session_id: str, request: SynapseRequest,
+    ):
+        """Having figured out a mxid for this user, complete the HTTP request
 
         Args:
-            user_id (unicode): complete @user:id
+            registered_user_id: The registered user ID to complete SSO login for.
+            request: The request to complete.
+            client_redirect_url: The URL to which to redirect the user at the end of the
+                process.
+        """
+        # Mark the stage of the authentication as successful.
+        # Save the user who authenticated with SSO, this will be used to ensure
+        # that the account be modified is also the person who logged in.
+        await self.store.mark_ui_auth_stage_complete(
+            session_id, LoginType.SSO, registered_user_id
+        )
 
-        Raises:
-            LimitExceededError if one of the ratelimiters' login requests count
-                for this user is too high too proceed.
+        # Render the HTML and return.
+        html_bytes = self._sso_auth_success_template.encode("utf-8")
+        request.setResponseCode(200)
+        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+        request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
+
+        request.write(html_bytes)
+        finish_request(request)
+
+    async def complete_sso_login(
+        self,
+        registered_user_id: str,
+        request: SynapseRequest,
+        client_redirect_url: str,
+    ):
+        """Having figured out a mxid for this user, complete the HTTP request
+
+        Args:
+            registered_user_id: The registered user ID to complete SSO login for.
+            request: The request to complete.
+            client_redirect_url: The URL to which to redirect the user at the end of the
+                process.
         """
-        self._failed_attempts_ratelimiter.ratelimit(
-            user_id.lower(),
-            time_now_s=self._clock.time(),
-            rate_hz=self.hs.config.rc_login_failed_attempts.per_second,
-            burst_count=self.hs.config.rc_login_failed_attempts.burst_count,
-            update=False,
+        # If the account has been deactivated, do not proceed with the login
+        # flow.
+        deactivated = await self.store.get_user_deactivated_status(registered_user_id)
+        if deactivated:
+            html_bytes = self._sso_account_deactivated_template.encode("utf-8")
+
+            request.setResponseCode(403)
+            request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+            request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
+            request.write(html_bytes)
+            finish_request(request)
+            return
+
+        self._complete_sso_login(registered_user_id, request, client_redirect_url)
+
+    def _complete_sso_login(
+        self,
+        registered_user_id: str,
+        request: SynapseRequest,
+        client_redirect_url: str,
+    ):
+        """
+        The synchronous portion of complete_sso_login.
+
+        This exists purely for backwards compatibility of synapse.module_api.ModuleApi.
+        """
+        # Create a login token
+        login_token = self.macaroon_gen.generate_short_term_login_token(
+            registered_user_id
         )
 
-        self._account_ratelimiter.ratelimit(
-            user_id.lower(),
-            time_now_s=self._clock.time(),
-            rate_hz=self.hs.config.rc_login_account.per_second,
-            burst_count=self.hs.config.rc_login_account.burst_count,
-            update=True,
+        # Append the login token to the original redirect URL (i.e. with its query
+        # parameters kept intact) to build the URL to which the template needs to
+        # redirect the users once they have clicked on the confirmation link.
+        redirect_url = self.add_query_param_to_url(
+            client_redirect_url, "loginToken", login_token
         )
 
+        # if the client is whitelisted, we can redirect straight to it
+        if client_redirect_url.startswith(self._whitelisted_sso_clients):
+            request.redirect(redirect_url)
+            finish_request(request)
+            return
+
+        # Otherwise, serve the redirect confirmation page.
+
+        # Remove the query parameters from the redirect URL to get a shorter version of
+        # it. This is only to display a human-readable URL in the template, but not the
+        # URL we redirect users to.
+        redirect_url_no_params = client_redirect_url.split("?")[0]
+
+        html_bytes = self._sso_redirect_confirm_template.render(
+            display_url=redirect_url_no_params,
+            redirect_url=redirect_url,
+            server_name=self._server_name,
+        ).encode("utf-8")
+
+        request.setResponseCode(200)
+        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+        request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
+        request.write(html_bytes)
+        finish_request(request)
+
+    @staticmethod
+    def add_query_param_to_url(url: str, param_name: str, param: Any):
+        url_parts = list(urllib.parse.urlparse(url))
+        query = dict(urllib.parse.parse_qsl(url_parts[4]))
+        query.update({param_name: param})
+        url_parts[4] = urllib.parse.urlencode(query)
+        return urllib.parse.urlunparse(url_parts)
+
 
 @attr.s
 class MacaroonGenerator(object):
 
     hs = attr.ib()
 
-    def generate_access_token(self, user_id, extra_caveats=None):
+    def generate_access_token(
+        self, user_id: str, extra_caveats: Optional[List[str]] = None
+    ) -> str:
         extra_caveats = extra_caveats or []
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = access")
@@ -1072,16 +1169,9 @@ class MacaroonGenerator(object):
             macaroon.add_first_party_caveat(caveat)
         return macaroon.serialize()
 
-    def generate_short_term_login_token(self, user_id, duration_in_ms=(2 * 60 * 1000)):
-        """
-
-        Args:
-            user_id (unicode):
-            duration_in_ms (int):
-
-        Returns:
-            unicode
-        """
+    def generate_short_term_login_token(
+        self, user_id: str, duration_in_ms: int = (2 * 60 * 1000)
+    ) -> str:
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = login")
         now = self.hs.get_clock().time_msec()
@@ -1089,12 +1179,12 @@ class MacaroonGenerator(object):
         macaroon.add_first_party_caveat("time < %d" % (expiry,))
         return macaroon.serialize()
 
-    def generate_delete_pusher_token(self, user_id):
+    def generate_delete_pusher_token(self, user_id: str) -> str:
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = delete_pusher")
         return macaroon.serialize()
 
-    def _generate_base_macaroon(self, user_id):
+    def _generate_base_macaroon(self, user_id: str) -> pymacaroons.Macaroon:
         macaroon = pymacaroons.Macaroon(
             location=self.hs.config.server_name,
             identifier="key",
diff --git a/synapse/handlers/cas_handler.py b/synapse/handlers/cas_handler.py
new file mode 100644
index 0000000000..64aaa1335c
--- /dev/null
+++ b/synapse/handlers/cas_handler.py
@@ -0,0 +1,221 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+import xml.etree.ElementTree as ET
+from typing import Dict, Optional, Tuple
+
+from six.moves import urllib
+
+from twisted.web.client import PartialDownloadError
+
+from synapse.api.errors import Codes, LoginError
+from synapse.http.site import SynapseRequest
+from synapse.types import UserID, map_username_to_mxid_localpart
+
+logger = logging.getLogger(__name__)
+
+
+class CasHandler:
+    """
+    Utility class for to handle the response from a CAS SSO service.
+
+    Args:
+        hs (synapse.server.HomeServer)
+    """
+
+    def __init__(self, hs):
+        self._hostname = hs.hostname
+        self._auth_handler = hs.get_auth_handler()
+        self._registration_handler = hs.get_registration_handler()
+
+        self._cas_server_url = hs.config.cas_server_url
+        self._cas_service_url = hs.config.cas_service_url
+        self._cas_displayname_attribute = hs.config.cas_displayname_attribute
+        self._cas_required_attributes = hs.config.cas_required_attributes
+
+        self._http_client = hs.get_proxied_http_client()
+
+    def _build_service_param(self, args: Dict[str, str]) -> str:
+        """
+        Generates a value to use as the "service" parameter when redirecting or
+        querying the CAS service.
+
+        Args:
+            args: Additional arguments to include in the final redirect URL.
+
+        Returns:
+            The URL to use as a "service" parameter.
+        """
+        return "%s%s?%s" % (
+            self._cas_service_url,
+            "/_matrix/client/r0/login/cas/ticket",
+            urllib.parse.urlencode(args),
+        )
+
+    async def _validate_ticket(
+        self, ticket: str, service_args: Dict[str, str]
+    ) -> Tuple[str, Optional[str]]:
+        """
+        Validate a CAS ticket with the server, parse the response, and return the user and display name.
+
+        Args:
+            ticket: The CAS ticket from the client.
+            service_args: Additional arguments to include in the service URL.
+                Should be the same as those passed to `get_redirect_url`.
+        """
+        uri = self._cas_server_url + "/proxyValidate"
+        args = {
+            "ticket": ticket,
+            "service": self._build_service_param(service_args),
+        }
+        try:
+            body = await self._http_client.get_raw(uri, args)
+        except PartialDownloadError as pde:
+            # Twisted raises this error if the connection is closed,
+            # even if that's being used old-http style to signal end-of-data
+            body = pde.response
+
+        user, attributes = self._parse_cas_response(body)
+        displayname = attributes.pop(self._cas_displayname_attribute, None)
+
+        for required_attribute, required_value in self._cas_required_attributes.items():
+            # If required attribute was not in CAS Response - Forbidden
+            if required_attribute not in attributes:
+                raise LoginError(401, "Unauthorized", errcode=Codes.UNAUTHORIZED)
+
+            # Also need to check value
+            if required_value is not None:
+                actual_value = attributes[required_attribute]
+                # If required attribute value does not match expected - Forbidden
+                if required_value != actual_value:
+                    raise LoginError(401, "Unauthorized", errcode=Codes.UNAUTHORIZED)
+
+        return user, displayname
+
+    def _parse_cas_response(
+        self, cas_response_body: str
+    ) -> Tuple[str, Dict[str, Optional[str]]]:
+        """
+        Retrieve the user and other parameters from the CAS response.
+
+        Args:
+            cas_response_body: The response from the CAS query.
+
+        Returns:
+            A tuple of the user and a mapping of other attributes.
+        """
+        user = None
+        attributes = {}
+        try:
+            root = ET.fromstring(cas_response_body)
+            if not root.tag.endswith("serviceResponse"):
+                raise Exception("root of CAS response is not serviceResponse")
+            success = root[0].tag.endswith("authenticationSuccess")
+            for child in root[0]:
+                if child.tag.endswith("user"):
+                    user = child.text
+                if child.tag.endswith("attributes"):
+                    for attribute in child:
+                        # ElementTree library expands the namespace in
+                        # attribute tags to the full URL of the namespace.
+                        # We don't care about namespace here and it will always
+                        # be encased in curly braces, so we remove them.
+                        tag = attribute.tag
+                        if "}" in tag:
+                            tag = tag.split("}")[1]
+                        attributes[tag] = attribute.text
+            if user is None:
+                raise Exception("CAS response does not contain user")
+        except Exception:
+            logger.exception("Error parsing CAS response")
+            raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+        if not success:
+            raise LoginError(
+                401, "Unsuccessful CAS response", errcode=Codes.UNAUTHORIZED
+            )
+        return user, attributes
+
+    def get_redirect_url(self, service_args: Dict[str, str]) -> str:
+        """
+        Generates a URL for the CAS server where the client should be redirected.
+
+        Args:
+            service_args: Additional arguments to include in the final redirect URL.
+
+        Returns:
+            The URL to redirect the client to.
+        """
+        args = urllib.parse.urlencode(
+            {"service": self._build_service_param(service_args)}
+        )
+
+        return "%s/login?%s" % (self._cas_server_url, args)
+
+    async def handle_ticket(
+        self,
+        request: SynapseRequest,
+        ticket: str,
+        client_redirect_url: Optional[str],
+        session: Optional[str],
+    ) -> None:
+        """
+        Called once the user has successfully authenticated with the SSO.
+        Validates a CAS ticket sent by the client and completes the auth process.
+
+        If the user interactive authentication session is provided, marks the
+        UI Auth session as complete, then returns an HTML page notifying the
+        user they are done.
+
+        Otherwise, this registers the user if necessary, and then returns a
+        redirect (with a login token) to the client.
+
+        Args:
+            request: the incoming request from the browser. We'll
+                respond to it with a redirect or an HTML page.
+
+            ticket: The CAS ticket provided by the client.
+
+            client_redirect_url: the redirectUrl parameter from the `/cas/ticket` HTTP request, if given.
+                This should be the same as the redirectUrl from the original `/login/sso/redirect` request.
+
+            session: The session parameter from the `/cas/ticket` HTTP request, if given.
+                This should be the UI Auth session id.
+        """
+        args = {}
+        if client_redirect_url:
+            args["redirectUrl"] = client_redirect_url
+        if session:
+            args["session"] = session
+        username, user_display_name = await self._validate_ticket(ticket, args)
+
+        localpart = map_username_to_mxid_localpart(username)
+        user_id = UserID(localpart, self._hostname).to_string()
+        registered_user_id = await self._auth_handler.check_user_exists(user_id)
+
+        if session:
+            await self._auth_handler.complete_sso_ui_auth(
+                registered_user_id, session, request,
+            )
+
+        else:
+            if not registered_user_id:
+                registered_user_id = await self._registration_handler.register_user(
+                    localpart=localpart, default_display_name=user_display_name
+                )
+
+            await self._auth_handler.complete_sso_login(
+                registered_user_id, request, client_redirect_url
+            )
diff --git a/synapse/handlers/deactivate_account.py b/synapse/handlers/deactivate_account.py
index 5f804d1f13..2afb390a92 100644
--- a/synapse/handlers/deactivate_account.py
+++ b/synapse/handlers/deactivate_account.py
@@ -15,8 +15,6 @@
 # limitations under the License.
 import logging
 
-from twisted.internet import defer
-
 from synapse.api.errors import SynapseError
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.types import UserID, create_requester
@@ -46,8 +44,7 @@ class DeactivateAccountHandler(BaseHandler):
 
         self._account_validity_enabled = hs.config.account_validity.enabled
 
-    @defer.inlineCallbacks
-    def deactivate_account(self, user_id, erase_data, id_server=None):
+    async def deactivate_account(self, user_id, erase_data, id_server=None):
         """Deactivate a user's account
 
         Args:
@@ -73,10 +70,12 @@ class DeactivateAccountHandler(BaseHandler):
         # unbinding
         identity_server_supports_unbinding = True
 
-        threepids = yield self.store.user_get_threepids(user_id)
+        # Retrieve the 3PIDs this user has bound to an identity server
+        threepids = await self.store.user_get_bound_threepids(user_id)
+
         for threepid in threepids:
             try:
-                result = yield self._identity_handler.try_unbind_threepid(
+                result = await self._identity_handler.try_unbind_threepid(
                     user_id,
                     {
                         "medium": threepid["medium"],
@@ -89,44 +88,83 @@ class DeactivateAccountHandler(BaseHandler):
                 # Do we want this to be a fatal error or should we carry on?
                 logger.exception("Failed to remove threepid from ID server")
                 raise SynapseError(400, "Failed to remove threepid from ID server")
-            yield self.store.user_delete_threepid(
+            await self.store.user_delete_threepid(
                 user_id, threepid["medium"], threepid["address"]
             )
 
+        # Remove all 3PIDs this user has bound to the homeserver
+        await self.store.user_delete_threepids(user_id)
+
         # delete any devices belonging to the user, which will also
         # delete corresponding access tokens.
-        yield self._device_handler.delete_all_devices_for_user(user_id)
+        await self._device_handler.delete_all_devices_for_user(user_id)
         # then delete any remaining access tokens which weren't associated with
         # a device.
-        yield self._auth_handler.delete_access_tokens_for_user(user_id)
+        await self._auth_handler.delete_access_tokens_for_user(user_id)
 
-        yield self.store.user_set_password_hash(user_id, None)
+        await self.store.user_set_password_hash(user_id, None)
 
         # Add the user to a table of users pending deactivation (ie.
         # removal from all the rooms they're a member of)
-        yield self.store.add_user_pending_deactivation(user_id)
+        await self.store.add_user_pending_deactivation(user_id)
 
         # delete from user directory
-        yield self.user_directory_handler.handle_user_deactivated(user_id)
+        await self.user_directory_handler.handle_user_deactivated(user_id)
 
         # Mark the user as erased, if they asked for that
         if erase_data:
             logger.info("Marking %s as erased", user_id)
-            yield self.store.mark_user_erased(user_id)
+            await self.store.mark_user_erased(user_id)
 
         # Now start the process that goes through that list and
         # parts users from rooms (if it isn't already running)
         self._start_user_parting()
 
+        # Reject all pending invites for the user, so that the user doesn't show up in the
+        # "invited" section of rooms' members list.
+        await self._reject_pending_invites_for_user(user_id)
+
         # Remove all information on the user from the account_validity table.
         if self._account_validity_enabled:
-            yield self.store.delete_account_validity_for_user(user_id)
+            await self.store.delete_account_validity_for_user(user_id)
 
         # Mark the user as deactivated.
-        yield self.store.set_user_deactivated_status(user_id, True)
+        await self.store.set_user_deactivated_status(user_id, True)
 
         return identity_server_supports_unbinding
 
+    async def _reject_pending_invites_for_user(self, user_id):
+        """Reject pending invites addressed to a given user ID.
+
+        Args:
+            user_id (str): The user ID to reject pending invites for.
+        """
+        user = UserID.from_string(user_id)
+        pending_invites = await self.store.get_invited_rooms_for_local_user(user_id)
+
+        for room in pending_invites:
+            try:
+                await self._room_member_handler.update_membership(
+                    create_requester(user),
+                    user,
+                    room.room_id,
+                    "leave",
+                    ratelimit=False,
+                    require_consent=False,
+                )
+                logger.info(
+                    "Rejected invite for deactivated user %r in room %r",
+                    user_id,
+                    room.room_id,
+                )
+            except Exception:
+                logger.exception(
+                    "Failed to reject invite for user %r in room %r:"
+                    " ignoring and continuing",
+                    user_id,
+                    room.room_id,
+                )
+
     def _start_user_parting(self):
         """
         Start the process that goes through the table of users
@@ -138,8 +176,7 @@ class DeactivateAccountHandler(BaseHandler):
         if not self._user_parter_running:
             run_as_background_process("user_parter_loop", self._user_parter_loop)
 
-    @defer.inlineCallbacks
-    def _user_parter_loop(self):
+    async def _user_parter_loop(self):
         """Loop that parts deactivated users from rooms
 
         Returns:
@@ -149,19 +186,18 @@ class DeactivateAccountHandler(BaseHandler):
         logger.info("Starting user parter")
         try:
             while True:
-                user_id = yield self.store.get_user_pending_deactivation()
+                user_id = await self.store.get_user_pending_deactivation()
                 if user_id is None:
                     break
                 logger.info("User parter parting %r", user_id)
-                yield self._part_user(user_id)
-                yield self.store.del_user_pending_deactivation(user_id)
+                await self._part_user(user_id)
+                await self.store.del_user_pending_deactivation(user_id)
                 logger.info("User parter finished parting %r", user_id)
             logger.info("User parter finished: stopping")
         finally:
             self._user_parter_running = False
 
-    @defer.inlineCallbacks
-    def _part_user(self, user_id):
+    async def _part_user(self, user_id):
         """Causes the given user_id to leave all the rooms they're joined to
 
         Returns:
@@ -169,11 +205,11 @@ class DeactivateAccountHandler(BaseHandler):
         """
         user = UserID.from_string(user_id)
 
-        rooms_for_user = yield self.store.get_rooms_for_user(user_id)
+        rooms_for_user = await self.store.get_rooms_for_user(user_id)
         for room_id in rooms_for_user:
             logger.info("User parter parting %r from %r", user_id, room_id)
             try:
-                yield self._room_member_handler.update_membership(
+                await self._room_member_handler.update_membership(
                     create_requester(user),
                     user,
                     room_id,
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 71a8f33da3..230d170258 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2016 OpenMarket Ltd
+# Copyright 2019 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -13,6 +15,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+from typing import Any, Dict, Optional
 
 from six import iteritems, itervalues
 
@@ -24,9 +27,15 @@ from synapse.api.errors import (
     FederationDeniedError,
     HttpResponseException,
     RequestSendFailed,
+    SynapseError,
 )
 from synapse.logging.opentracing import log_kv, set_tag, trace
-from synapse.types import RoomStreamToken, get_domain_from_id
+from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.types import (
+    RoomStreamToken,
+    get_domain_from_id,
+    get_verify_key_from_cross_signing_key,
+)
 from synapse.util import stringutils
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -37,6 +46,8 @@ from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
+MAX_DEVICE_DISPLAY_NAME_LEN = 100
+
 
 class DeviceWorkerHandler(BaseHandler):
     def __init__(self, hs):
@@ -44,6 +55,7 @@ class DeviceWorkerHandler(BaseHandler):
 
         self.hs = hs
         self.state = hs.get_state_handler()
+        self.state_store = hs.get_storage().state
         self._auth_handler = hs.get_auth_handler()
 
     @trace
@@ -119,8 +131,14 @@ class DeviceWorkerHandler(BaseHandler):
         users_who_share_room = yield self.store.get_users_who_share_room_with_user(
             user_id
         )
+
+        tracked_users = set(users_who_share_room)
+
+        # Always tell the user about their own devices
+        tracked_users.add(user_id)
+
         changed = yield self.store.get_users_whose_devices_changed(
-            from_token.device_list_key, users_who_share_room
+            from_token.device_list_key, tracked_users
         )
 
         # Then work out if any users have since joined
@@ -176,7 +194,7 @@ class DeviceWorkerHandler(BaseHandler):
                 continue
 
             # mapping from event_id -> state_dict
-            prev_state_ids = yield self.store.get_state_ids_for_events(event_ids)
+            prev_state_ids = yield self.state_store.get_state_ids_for_events(event_ids)
 
             # Check if we've joined the room? If so we just blindly add all the users to
             # the "possibly changed" users.
@@ -222,6 +240,22 @@ class DeviceWorkerHandler(BaseHandler):
 
         return result
 
+    @defer.inlineCallbacks
+    def on_federation_query_user_devices(self, user_id):
+        stream_id, devices = yield self.store.get_devices_with_keys_by_user(user_id)
+        master_key = yield self.store.get_e2e_cross_signing_key(user_id, "master")
+        self_signing_key = yield self.store.get_e2e_cross_signing_key(
+            user_id, "self_signing"
+        )
+
+        return {
+            "user_id": user_id,
+            "stream_id": stream_id,
+            "devices": devices,
+            "master_key": master_key,
+            "self_signing_key": self_signing_key,
+        }
+
 
 class DeviceHandler(DeviceWorkerHandler):
     def __init__(self, hs):
@@ -236,9 +270,6 @@ class DeviceHandler(DeviceWorkerHandler):
         federation_registry.register_edu_handler(
             "m.device_list_update", self.device_list_updater.incoming_device_list_update
         )
-        federation_registry.register_query_handler(
-            "user_devices", self.on_federation_query_user_devices
-        )
 
         hs.get_distributor().observe("user_left_room", self.user_left_room)
 
@@ -313,8 +344,10 @@ class DeviceHandler(DeviceWorkerHandler):
             else:
                 raise
 
-        yield self._auth_handler.delete_access_tokens_for_user(
-            user_id, device_id=device_id
+        yield defer.ensureDeferred(
+            self._auth_handler.delete_access_tokens_for_user(
+                user_id, device_id=device_id
+            )
         )
 
         yield self.store.delete_e2e_keys_by_device(user_id=user_id, device_id=device_id)
@@ -366,8 +399,10 @@ class DeviceHandler(DeviceWorkerHandler):
         # Delete access tokens and e2e keys for each device. Not optimised as it is not
         # considered as part of a critical path.
         for device_id in device_ids:
-            yield self._auth_handler.delete_access_tokens_for_user(
-                user_id, device_id=device_id
+            yield defer.ensureDeferred(
+                self._auth_handler.delete_access_tokens_for_user(
+                    user_id, device_id=device_id
+                )
             )
             yield self.store.delete_e2e_keys_by_device(
                 user_id=user_id, device_id=device_id
@@ -388,9 +423,18 @@ class DeviceHandler(DeviceWorkerHandler):
             defer.Deferred:
         """
 
+        # Reject a new displayname which is too long.
+        new_display_name = content.get("display_name")
+        if new_display_name and len(new_display_name) > MAX_DEVICE_DISPLAY_NAME_LEN:
+            raise SynapseError(
+                400,
+                "Device display name is too long (max %i)"
+                % (MAX_DEVICE_DISPLAY_NAME_LEN,),
+            )
+
         try:
             yield self.store.update_device(
-                user_id, device_id, new_display_name=content.get("display_name")
+                user_id, device_id, new_display_name=new_display_name
             )
             yield self.notify_device_update(user_id, [device_id])
         except errors.StoreError as e:
@@ -428,7 +472,11 @@ class DeviceHandler(DeviceWorkerHandler):
 
         room_ids = yield self.store.get_rooms_for_user(user_id)
 
-        yield self.notifier.on_new_event("device_list_key", position, rooms=room_ids)
+        # specify the user ID too since the user should always get their own device list
+        # updates, even if they aren't in any rooms.
+        yield self.notifier.on_new_event(
+            "device_list_key", position, users=[user_id], rooms=room_ids
+        )
 
         if hosts:
             logger.info(
@@ -439,9 +487,19 @@ class DeviceHandler(DeviceWorkerHandler):
                 log_kv({"message": "sent device update to host", "host": host})
 
     @defer.inlineCallbacks
-    def on_federation_query_user_devices(self, user_id):
-        stream_id, devices = yield self.store.get_devices_with_keys_by_user(user_id)
-        return {"user_id": user_id, "stream_id": stream_id, "devices": devices}
+    def notify_user_signature_update(self, from_user_id, user_ids):
+        """Notify a user that they have made new signatures of other users.
+
+        Args:
+            from_user_id (str): the user who made the signature
+            user_ids (list[str]): the users IDs that have new signatures
+        """
+
+        position = yield self.store.add_user_signature_change_to_streams(
+            from_user_id, user_ids
+        )
+
+        self.notifier.on_new_event("device_list_key", position, users=[from_user_id])
 
     @defer.inlineCallbacks
     def user_left_room(self, user, room_id):
@@ -483,6 +541,15 @@ class DeviceListUpdater(object):
             iterable=True,
         )
 
+        # Attempt to resync out of sync device lists every 30s.
+        self._resync_retry_in_progress = False
+        self.clock.looping_call(
+            run_as_background_process,
+            30 * 1000,
+            func=self._maybe_retry_device_resync,
+            desc="_maybe_retry_device_resync",
+        )
+
     @trace
     @defer.inlineCallbacks
     def incoming_device_list_update(self, origin, edu_content):
@@ -569,7 +636,13 @@ class DeviceListUpdater(object):
             # happens if we've missed updates.
             resync = yield self._need_to_do_resync(user_id, pending_updates)
 
-            logger.debug("Need to re-sync devices for %r? %r", user_id, resync)
+            if logger.isEnabledFor(logging.INFO):
+                logger.info(
+                    "Received device list update for %s, requiring resync: %s. Devices: %s",
+                    user_id,
+                    resync,
+                    ", ".join(u[0] for u in pending_updates),
+                )
 
             if resync:
                 yield self.user_device_resync(user_id)
@@ -621,25 +694,83 @@ class DeviceListUpdater(object):
         return False
 
     @defer.inlineCallbacks
-    def user_device_resync(self, user_id):
+    def _maybe_retry_device_resync(self):
+        """Retry to resync device lists that are out of sync, except if another retry is
+        in progress.
+        """
+        if self._resync_retry_in_progress:
+            return
+
+        try:
+            # Prevent another call of this function to retry resyncing device lists so
+            # we don't send too many requests.
+            self._resync_retry_in_progress = True
+            # Get all of the users that need resyncing.
+            need_resync = yield self.store.get_user_ids_requiring_device_list_resync()
+            # Iterate over the set of user IDs.
+            for user_id in need_resync:
+                try:
+                    # Try to resync the current user's devices list.
+                    result = yield self.user_device_resync(
+                        user_id=user_id, mark_failed_as_stale=False,
+                    )
+
+                    # user_device_resync only returns a result if it managed to
+                    # successfully resync and update the database. Updating the table
+                    # of users requiring resync isn't necessary here as
+                    # user_device_resync already does it (through
+                    # self.store.update_remote_device_list_cache).
+                    if result:
+                        logger.debug(
+                            "Successfully resynced the device list for %s", user_id,
+                        )
+                except Exception as e:
+                    # If there was an issue resyncing this user, e.g. if the remote
+                    # server sent a malformed result, just log the error instead of
+                    # aborting all the subsequent resyncs.
+                    logger.debug(
+                        "Could not resync the device list for %s: %s", user_id, e,
+                    )
+        finally:
+            # Allow future calls to retry resyncinc out of sync device lists.
+            self._resync_retry_in_progress = False
+
+    @defer.inlineCallbacks
+    def user_device_resync(self, user_id, mark_failed_as_stale=True):
         """Fetches all devices for a user and updates the device cache with them.
 
         Args:
             user_id (str): The user's id whose device_list will be updated.
+            mark_failed_as_stale (bool): Whether to mark the user's device list as stale
+                if the attempt to resync failed.
         Returns:
             Deferred[dict]: a dict with device info as under the "devices" in the result of this
             request:
             https://matrix.org/docs/spec/server_server/r0.1.2#get-matrix-federation-v1-user-devices-userid
         """
+        logger.debug("Attempting to resync the device list for %s", user_id)
         log_kv({"message": "Doing resync to update device list."})
         # Fetch all devices for the user.
         origin = get_domain_from_id(user_id)
         try:
             result = yield self.federation.query_user_devices(origin, user_id)
-        except (NotRetryingDestination, RequestSendFailed, HttpResponseException):
-            # TODO: Remember that we are now out of sync and try again
-            # later
-            logger.warn("Failed to handle device list update for %s", user_id)
+        except NotRetryingDestination:
+            if mark_failed_as_stale:
+                # Mark the remote user's device list as stale so we know we need to retry
+                # it later.
+                yield self.store.mark_remote_user_device_cache_as_stale(user_id)
+
+            return
+        except (RequestSendFailed, HttpResponseException) as e:
+            logger.warning(
+                "Failed to handle device list update for %s: %s", user_id, e,
+            )
+
+            if mark_failed_as_stale:
+                # Mark the remote user's device list as stale so we know we need to retry
+                # it later.
+                yield self.store.mark_remote_user_device_cache_as_stale(user_id)
+
             # We abort on exceptions rather than accepting the update
             # as otherwise synapse will 'forget' that its device list
             # is out of date. If we bail then we will retry the resync
@@ -653,18 +784,29 @@ class DeviceListUpdater(object):
             logger.info(e)
             return
         except Exception as e:
-            # TODO: Remember that we are now out of sync and try again
-            # later
             set_tag("error", True)
             log_kv(
                 {"message": "Exception raised by federation request", "exception": e}
             )
             logger.exception("Failed to handle device list update for %s", user_id)
+
+            if mark_failed_as_stale:
+                # Mark the remote user's device list as stale so we know we need to retry
+                # it later.
+                yield self.store.mark_remote_user_device_cache_as_stale(user_id)
+
             return
         log_kv({"result": result})
         stream_id = result["stream_id"]
         devices = result["devices"]
 
+        # Get the master key and the self-signing key for this user if provided in the
+        # response (None if not in the response).
+        # The response will not contain the user signing key, as this key is only used by
+        # its owner, thus it doesn't make sense to send it over federation.
+        master_key = result.get("master_key")
+        self_signing_key = result.get("self_signing_key")
+
         # If the remote server has more than ~1000 devices for this user
         # we assume that something is going horribly wrong (e.g. a bot
         # that logs in and creates a new device every time it tries to
@@ -677,7 +819,7 @@ class DeviceListUpdater(object):
         # up on storing the total list of devices and only handle the
         # delta instead.
         if len(devices) > 1000:
-            logger.warn(
+            logger.warning(
                 "Ignoring device list snapshot for %s as it has >1K devs (%d)",
                 user_id,
                 len(devices),
@@ -694,10 +836,54 @@ class DeviceListUpdater(object):
 
         yield self.store.update_remote_device_list_cache(user_id, devices, stream_id)
         device_ids = [device["device_id"] for device in devices]
+
+        # Handle cross-signing keys.
+        cross_signing_device_ids = yield self.process_cross_signing_key_update(
+            user_id, master_key, self_signing_key,
+        )
+        device_ids = device_ids + cross_signing_device_ids
+
         yield self.device_handler.notify_device_update(user_id, device_ids)
 
         # We clobber the seen updates since we've re-synced from a given
         # point.
-        self._seen_updates[user_id] = set([stream_id])
+        self._seen_updates[user_id] = {stream_id}
 
         defer.returnValue(result)
+
+    @defer.inlineCallbacks
+    def process_cross_signing_key_update(
+        self,
+        user_id: str,
+        master_key: Optional[Dict[str, Any]],
+        self_signing_key: Optional[Dict[str, Any]],
+    ) -> list:
+        """Process the given new master and self-signing key for the given remote user.
+
+        Args:
+            user_id: The ID of the user these keys are for.
+            master_key: The dict of the cross-signing master key as returned by the
+                remote server.
+            self_signing_key: The dict of the cross-signing self-signing key as returned
+                by the remote server.
+
+        Return:
+            The device IDs for the given keys.
+        """
+        device_ids = []
+
+        if master_key:
+            yield self.store.set_e2e_cross_signing_key(user_id, "master", master_key)
+            _, verify_key = get_verify_key_from_cross_signing_key(master_key)
+            # verify_key is a VerifyKey from signedjson, which uses
+            # .version to denote the portion of the key ID after the
+            # algorithm and colon, which is the device ID
+            device_ids.append(verify_key.version)
+        if self_signing_key:
+            yield self.store.set_e2e_cross_signing_key(
+                user_id, "self_signing", self_signing_key
+            )
+            _, verify_key = get_verify_key_from_cross_signing_key(self_signing_key)
+            device_ids.append(verify_key.version)
+
+        return device_ids
diff --git a/synapse/handlers/devicemessage.py b/synapse/handlers/devicemessage.py
index 0043cbea17..05c4b3eec0 100644
--- a/synapse/handlers/devicemessage.py
+++ b/synapse/handlers/devicemessage.py
@@ -14,12 +14,14 @@
 # limitations under the License.
 
 import logging
+from typing import Any, Dict
 
 from canonicaljson import json
 
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
+from synapse.logging.context import run_in_background
 from synapse.logging.opentracing import (
     get_active_span_text_map,
     log_kv,
@@ -47,12 +49,14 @@ class DeviceMessageHandler(object):
             "m.direct_to_device", self.on_direct_to_device_edu
         )
 
+        self._device_list_updater = hs.get_device_handler().device_list_updater
+
     @defer.inlineCallbacks
     def on_direct_to_device_edu(self, origin, content):
         local_messages = {}
         sender_user_id = content["sender"]
         if origin != get_domain_from_id(sender_user_id):
-            logger.warn(
+            logger.warning(
                 "Dropping device message from %r with spoofed sender %r",
                 origin,
                 sender_user_id,
@@ -65,6 +69,9 @@ class DeviceMessageHandler(object):
                 logger.warning("Request for keys for non-local user %s", user_id)
                 raise SynapseError(400, "Not a user here")
 
+            if not by_device:
+                continue
+
             messages_by_device = {
                 device_id: {
                     "content": message_content,
@@ -73,8 +80,11 @@ class DeviceMessageHandler(object):
                 }
                 for device_id, message_content in by_device.items()
             }
-            if messages_by_device:
-                local_messages[user_id] = messages_by_device
+            local_messages[user_id] = messages_by_device
+
+            yield self._check_for_unknown_devices(
+                message_type, sender_user_id, by_device
+            )
 
         stream_id = yield self.store.add_messages_from_remote_to_device_inbox(
             origin, message_id, local_messages
@@ -85,6 +95,55 @@ class DeviceMessageHandler(object):
         )
 
     @defer.inlineCallbacks
+    def _check_for_unknown_devices(
+        self,
+        message_type: str,
+        sender_user_id: str,
+        by_device: Dict[str, Dict[str, Any]],
+    ):
+        """Checks inbound device messages for unkown remote devices, and if
+        found marks the remote cache for the user as stale.
+        """
+
+        if message_type != "m.room_key_request":
+            return
+
+        # Get the sending device IDs
+        requesting_device_ids = set()
+        for message_content in by_device.values():
+            device_id = message_content.get("requesting_device_id")
+            requesting_device_ids.add(device_id)
+
+        # Check if we are tracking the devices of the remote user.
+        room_ids = yield self.store.get_rooms_for_user(sender_user_id)
+        if not room_ids:
+            logger.info(
+                "Received device message from remote device we don't"
+                " share a room with: %s %s",
+                sender_user_id,
+                requesting_device_ids,
+            )
+            return
+
+        # If we are tracking check that we know about the sending
+        # devices.
+        cached_devices = yield self.store.get_cached_devices_for_user(sender_user_id)
+
+        unknown_devices = requesting_device_ids - set(cached_devices)
+        if unknown_devices:
+            logger.info(
+                "Received device message from remote device not in our cache: %s %s",
+                sender_user_id,
+                unknown_devices,
+            )
+            yield self.store.mark_remote_user_device_cache_as_stale(sender_user_id)
+
+            # Immediately attempt a resync in the background
+            run_in_background(
+                self._device_list_updater.user_device_resync, sender_user_id
+            )
+
+    @defer.inlineCallbacks
     def send_device_message(self, sender_user_id, message_type, messages):
         set_tag("number_of_messages", len(messages))
         set_tag("sender", sender_user_id)
diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index 526379c6f7..f2f16b1e43 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -13,9 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
 import logging
 import string
+from typing import Iterable, List, Optional
 
 from twisted.internet import defer
 
@@ -28,7 +28,8 @@ from synapse.api.errors import (
     StoreError,
     SynapseError,
 )
-from synapse.types import RoomAlias, UserID, get_domain_from_id
+from synapse.appservice import ApplicationService
+from synapse.types import Requester, RoomAlias, UserID, get_domain_from_id
 
 from ._base import BaseHandler
 
@@ -55,7 +56,13 @@ class DirectoryHandler(BaseHandler):
         self.spam_checker = hs.get_spam_checker()
 
     @defer.inlineCallbacks
-    def _create_association(self, room_alias, room_id, servers=None, creator=None):
+    def _create_association(
+        self,
+        room_alias: RoomAlias,
+        room_id: str,
+        servers: Optional[Iterable[str]] = None,
+        creator: Optional[str] = None,
+    ):
         # general association creation for both human users and app services
 
         for wchar in string.whitespace:
@@ -70,7 +77,7 @@ class DirectoryHandler(BaseHandler):
         # TODO(erikj): Check if there is a current association.
         if not servers:
             users = yield self.state.get_current_users_in_room(room_id)
-            servers = set(get_domain_from_id(u) for u in users)
+            servers = {get_domain_from_id(u) for u in users}
 
         if not servers:
             raise SynapseError(400, "Failed to get server list")
@@ -79,26 +86,22 @@ class DirectoryHandler(BaseHandler):
             room_alias, room_id, servers, creator=creator
         )
 
-    @defer.inlineCallbacks
-    def create_association(
+    async def create_association(
         self,
-        requester,
-        room_alias,
-        room_id,
-        servers=None,
-        send_event=True,
-        check_membership=True,
+        requester: Requester,
+        room_alias: RoomAlias,
+        room_id: str,
+        servers: Optional[List[str]] = None,
+        check_membership: bool = True,
     ):
         """Attempt to create a new alias
 
         Args:
-            requester (Requester)
-            room_alias (RoomAlias)
-            room_id (str)
-            servers (list[str]|None): List of servers that others servers
-                should try and join via
-            send_event (bool): Whether to send an updated m.room.aliases event
-            check_membership (bool): Whether to check if the user is in the room
+            requester
+            room_alias
+            room_id
+            servers: Iterable of servers that others servers should try and join via
+            check_membership: Whether to check if the user is in the room
                 before the alias can be set (if the server's config requires it).
 
         Returns:
@@ -119,12 +122,16 @@ class DirectoryHandler(BaseHandler):
             if not service.is_interested_in_alias(room_alias.to_string()):
                 raise SynapseError(
                     400,
-                    "This application service has not reserved" " this kind of alias.",
+                    "This application service has not reserved this kind of alias.",
                     errcode=Codes.EXCLUSIVE,
                 )
         else:
-            if self.require_membership and check_membership:
-                rooms_for_user = yield self.store.get_rooms_for_user(user_id)
+            # Server admins are not subject to the same constraints as normal
+            # users when creating an alias (e.g. being in the room).
+            is_admin = await self.auth.is_server_admin(requester.user)
+
+            if (self.require_membership and check_membership) and not is_admin:
+                rooms_for_user = await self.store.get_rooms_for_user(user_id)
                 if room_id not in rooms_for_user:
                     raise AuthError(
                         403, "You must be in the room to create an alias for it"
@@ -141,7 +148,7 @@ class DirectoryHandler(BaseHandler):
                 # per alias creation rule?
                 raise SynapseError(403, "Not allowed to create alias")
 
-            can_create = yield self.can_modify_alias(room_alias, user_id=user_id)
+            can_create = await self.can_modify_alias(room_alias, user_id=user_id)
             if not can_create:
                 raise AuthError(
                     400,
@@ -149,23 +156,17 @@ class DirectoryHandler(BaseHandler):
                     errcode=Codes.EXCLUSIVE,
                 )
 
-        yield self._create_association(room_alias, room_id, servers, creator=user_id)
-        if send_event:
-            yield self.send_room_alias_update_event(requester, room_id)
+        await self._create_association(room_alias, room_id, servers, creator=user_id)
 
-    @defer.inlineCallbacks
-    def delete_association(self, requester, room_alias, send_event=True):
+    async def delete_association(self, requester: Requester, room_alias: RoomAlias):
         """Remove an alias from the directory
 
         (this is only meant for human users; AS users should call
         delete_appservice_association)
 
         Args:
-            requester (Requester):
-            room_alias (RoomAlias):
-            send_event (bool): Whether to send an updated m.room.aliases event.
-                Note that, if we delete the canonical alias, we will always attempt
-                to send an m.room.canonical_alias event
+            requester
+            room_alias
 
         Returns:
             Deferred[unicode]: room id that the alias used to point to
@@ -181,7 +182,7 @@ class DirectoryHandler(BaseHandler):
         user_id = requester.user.to_string()
 
         try:
-            can_delete = yield self._user_can_delete_alias(room_alias, user_id)
+            can_delete = await self._user_can_delete_alias(room_alias, user_id)
         except StoreError as e:
             if e.code == 404:
                 raise NotFoundError("Unknown room alias")
@@ -190,7 +191,7 @@ class DirectoryHandler(BaseHandler):
         if not can_delete:
             raise AuthError(403, "You don't have permission to delete the alias.")
 
-        can_delete = yield self.can_modify_alias(room_alias, user_id=user_id)
+        can_delete = await self.can_modify_alias(room_alias, user_id=user_id)
         if not can_delete:
             raise SynapseError(
                 400,
@@ -198,22 +199,19 @@ class DirectoryHandler(BaseHandler):
                 errcode=Codes.EXCLUSIVE,
             )
 
-        room_id = yield self._delete_association(room_alias)
+        room_id = await self._delete_association(room_alias)
 
         try:
-            if send_event:
-                yield self.send_room_alias_update_event(requester, room_id)
-
-            yield self._update_canonical_alias(
-                requester, requester.user.to_string(), room_id, room_alias
-            )
+            await self._update_canonical_alias(requester, user_id, room_id, room_alias)
         except AuthError as e:
             logger.info("Failed to update alias events: %s", e)
 
         return room_id
 
     @defer.inlineCallbacks
-    def delete_appservice_association(self, service, room_alias):
+    def delete_appservice_association(
+        self, service: ApplicationService, room_alias: RoomAlias
+    ):
         if not service.is_interested_in_alias(room_alias.to_string()):
             raise SynapseError(
                 400,
@@ -223,7 +221,7 @@ class DirectoryHandler(BaseHandler):
         yield self._delete_association(room_alias)
 
     @defer.inlineCallbacks
-    def _delete_association(self, room_alias):
+    def _delete_association(self, room_alias: RoomAlias):
         if not self.hs.is_mine(room_alias):
             raise SynapseError(400, "Room alias must be local")
 
@@ -232,7 +230,7 @@ class DirectoryHandler(BaseHandler):
         return room_id
 
     @defer.inlineCallbacks
-    def get_association(self, room_alias):
+    def get_association(self, room_alias: RoomAlias):
         room_id = None
         if self.hs.is_mine(room_alias):
             result = yield self.get_association_from_room_alias(room_alias)
@@ -250,7 +248,7 @@ class DirectoryHandler(BaseHandler):
                     ignore_backoff=True,
                 )
             except CodeMessageException as e:
-                logging.warn("Error retrieving alias")
+                logging.warning("Error retrieving alias")
                 if e.code == 404:
                     result = None
                 else:
@@ -268,7 +266,7 @@ class DirectoryHandler(BaseHandler):
             )
 
         users = yield self.state.get_current_users_in_room(room_id)
-        extra_servers = set(get_domain_from_id(u) for u in users)
+        extra_servers = {get_domain_from_id(u) for u in users}
         servers = set(extra_servers) | set(servers)
 
         # If this server is in the list of servers, return it first.
@@ -283,7 +281,7 @@ class DirectoryHandler(BaseHandler):
     def on_directory_query(self, args):
         room_alias = RoomAlias.from_string(args["room_alias"])
         if not self.hs.is_mine(room_alias):
-            raise SynapseError(400, "Room Alias is not hosted on this Home Server")
+            raise SynapseError(400, "Room Alias is not hosted on this homeserver")
 
         result = yield self.get_association_from_room_alias(room_alias)
 
@@ -296,46 +294,58 @@ class DirectoryHandler(BaseHandler):
                 Codes.NOT_FOUND,
             )
 
-    @defer.inlineCallbacks
-    def send_room_alias_update_event(self, requester, room_id):
-        aliases = yield self.store.get_aliases_for_room(room_id)
-
-        yield self.event_creation_handler.create_and_send_nonmember_event(
-            requester,
-            {
-                "type": EventTypes.Aliases,
-                "state_key": self.hs.hostname,
-                "room_id": room_id,
-                "sender": requester.user.to_string(),
-                "content": {"aliases": aliases},
-            },
-            ratelimit=False,
-        )
-
-    @defer.inlineCallbacks
-    def _update_canonical_alias(self, requester, user_id, room_id, room_alias):
-        alias_event = yield self.state.get_current_state(
+    async def _update_canonical_alias(
+        self, requester: Requester, user_id: str, room_id: str, room_alias: RoomAlias
+    ):
+        """
+        Send an updated canonical alias event if the removed alias was set as
+        the canonical alias or listed in the alt_aliases field.
+        """
+        alias_event = await self.state.get_current_state(
             room_id, EventTypes.CanonicalAlias, ""
         )
 
-        alias_str = room_alias.to_string()
-        if not alias_event or alias_event.content.get("alias", "") != alias_str:
+        # There is no canonical alias, nothing to do.
+        if not alias_event:
             return
 
-        yield self.event_creation_handler.create_and_send_nonmember_event(
-            requester,
-            {
-                "type": EventTypes.CanonicalAlias,
-                "state_key": "",
-                "room_id": room_id,
-                "sender": user_id,
-                "content": {},
-            },
-            ratelimit=False,
-        )
+        # Obtain a mutable version of the event content.
+        content = dict(alias_event.content)
+        send_update = False
+
+        # Remove the alias property if it matches the removed alias.
+        alias_str = room_alias.to_string()
+        if alias_event.content.get("alias", "") == alias_str:
+            send_update = True
+            content.pop("alias", "")
+
+        # Filter the alt_aliases property for the removed alias. Note that the
+        # value is not modified if alt_aliases is of an unexpected form.
+        alt_aliases = content.get("alt_aliases")
+        if isinstance(alt_aliases, (list, tuple)) and alias_str in alt_aliases:
+            send_update = True
+            alt_aliases = [alias for alias in alt_aliases if alias != alias_str]
+
+            if alt_aliases:
+                content["alt_aliases"] = alt_aliases
+            else:
+                del content["alt_aliases"]
+
+        if send_update:
+            await self.event_creation_handler.create_and_send_nonmember_event(
+                requester,
+                {
+                    "type": EventTypes.CanonicalAlias,
+                    "state_key": "",
+                    "room_id": room_id,
+                    "sender": user_id,
+                    "content": content,
+                },
+                ratelimit=False,
+            )
 
     @defer.inlineCallbacks
-    def get_association_from_room_alias(self, room_alias):
+    def get_association_from_room_alias(self, room_alias: RoomAlias):
         result = yield self.store.get_association_from_room_alias(room_alias)
         if not result:
             # Query AS to see if it exists
@@ -343,7 +353,7 @@ class DirectoryHandler(BaseHandler):
             result = yield as_handler.query_room_alias_exists(room_alias)
         return result
 
-    def can_modify_alias(self, alias, user_id=None):
+    def can_modify_alias(self, alias: RoomAlias, user_id: Optional[str] = None):
         # Any application service "interested" in an alias they are regexing on
         # can modify the alias.
         # Users can only modify the alias if ALL the interested services have
@@ -363,23 +373,41 @@ class DirectoryHandler(BaseHandler):
         # either no interested services, or no service with an exclusive lock
         return defer.succeed(True)
 
-    @defer.inlineCallbacks
-    def _user_can_delete_alias(self, alias, user_id):
-        creator = yield self.store.get_room_alias_creator(alias.to_string())
+    async def _user_can_delete_alias(self, alias: RoomAlias, user_id: str):
+        """Determine whether a user can delete an alias.
+
+        One of the following must be true:
+
+        1. The user created the alias.
+        2. The user is a server administrator.
+        3. The user has a power-level sufficient to send a canonical alias event
+           for the current room.
+
+        """
+        creator = await self.store.get_room_alias_creator(alias.to_string())
 
         if creator is not None and creator == user_id:
             return True
 
-        is_admin = yield self.auth.is_server_admin(UserID.from_string(user_id))
-        return is_admin
+        # Resolve the alias to the corresponding room.
+        room_mapping = await self.get_association(alias)
+        room_id = room_mapping["room_id"]
+        if not room_id:
+            return False
 
-    @defer.inlineCallbacks
-    def edit_published_room_list(self, requester, room_id, visibility):
+        res = await self.auth.check_can_change_room_list(
+            room_id, UserID.from_string(user_id)
+        )
+        return res
+
+    async def edit_published_room_list(
+        self, requester: Requester, room_id: str, visibility: str
+    ):
         """Edit the entry of the room in the published room list.
 
         requester
-        room_id (str)
-        visibility (str): "public" or "private"
+        room_id
+        visibility: "public" or "private"
         """
         user_id = requester.user.to_string()
 
@@ -400,16 +428,24 @@ class DirectoryHandler(BaseHandler):
                 403, "This user is not permitted to publish rooms to the room list"
             )
 
-        room = yield self.store.get_room(room_id)
+        room = await self.store.get_room(room_id)
         if room is None:
             raise SynapseError(400, "Unknown room")
 
-        yield self.auth.check_can_change_room_list(room_id, requester.user)
+        can_change_room_list = await self.auth.check_can_change_room_list(
+            room_id, requester.user
+        )
+        if not can_change_room_list:
+            raise AuthError(
+                403,
+                "This server requires you to be a moderator in the room to"
+                " edit its room list entry",
+            )
 
         making_public = visibility == "public"
         if making_public:
-            room_aliases = yield self.store.get_aliases_for_room(room_id)
-            canonical_alias = yield self.store.get_canonical_alias_for_room(room_id)
+            room_aliases = await self.store.get_aliases_for_room(room_id)
+            canonical_alias = await self.store.get_canonical_alias_for_room(room_id)
             if canonical_alias:
                 room_aliases.append(canonical_alias)
 
@@ -421,20 +457,20 @@ class DirectoryHandler(BaseHandler):
                 # per alias creation rule?
                 raise SynapseError(403, "Not allowed to publish room")
 
-        yield self.store.set_room_is_public(room_id, making_public)
+        await self.store.set_room_is_public(room_id, making_public)
 
     @defer.inlineCallbacks
     def edit_published_appservice_room_list(
-        self, appservice_id, network_id, room_id, visibility
+        self, appservice_id: str, network_id: str, room_id: str, visibility: str
     ):
         """Add or remove a room from the appservice/network specific public
         room list.
 
         Args:
-            appservice_id (str): ID of the appservice that owns the list
-            network_id (str): The ID of the network the list is associated with
-            room_id (str)
-            visibility (str): either "public" or "private"
+            appservice_id: ID of the appservice that owns the list
+            network_id: The ID of the network the list is associated with
+            room_id
+            visibility: either "public" or "private"
         """
         if visibility not in ["public", "private"]:
             raise SynapseError(400, "Invalid visibility setting")
@@ -442,3 +478,19 @@ class DirectoryHandler(BaseHandler):
         yield self.store.set_room_is_public_appservice(
             room_id, appservice_id, network_id, visibility == "public"
         )
+
+    async def get_aliases_for_room(
+        self, requester: Requester, room_id: str
+    ) -> List[str]:
+        """
+        Get a list of the aliases that currently point to this room on this server
+        """
+        # allow access to server admins and current members of the room
+        is_admin = await self.auth.is_server_admin(requester.user)
+        if not is_admin:
+            await self.auth.check_user_in_room_or_world_readable(
+                room_id, requester.user.to_string()
+            )
+
+        aliases = await self.store.get_aliases_for_room(room_id)
+        return aliases
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 056fb97acb..774a252619 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2016 OpenMarket Ltd
-# Copyright 2018 New Vector Ltd
+# Copyright 2018-2019 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -18,15 +19,26 @@ import logging
 
 from six import iteritems
 
+import attr
 from canonicaljson import encode_canonical_json, json
+from signedjson.key import decode_verify_key_bytes
+from signedjson.sign import SignatureVerifyException, verify_signed_json
+from unpaddedbase64 import decode_base64
 
 from twisted.internet import defer
 
-from synapse.api.errors import CodeMessageException, SynapseError
+from synapse.api.errors import CodeMessageException, Codes, NotFoundError, SynapseError
 from synapse.logging.context import make_deferred_yieldable, run_in_background
 from synapse.logging.opentracing import log_kv, set_tag, tag_args, trace
-from synapse.types import UserID, get_domain_from_id
+from synapse.replication.http.devices import ReplicationUserDevicesResyncRestServlet
+from synapse.types import (
+    UserID,
+    get_domain_from_id,
+    get_verify_key_from_cross_signing_key,
+)
 from synapse.util import unwrapFirstError
+from synapse.util.async_helpers import Linearizer
+from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.retryutils import NotRetryingDestination
 
 logger = logging.getLogger(__name__)
@@ -40,16 +52,35 @@ class E2eKeysHandler(object):
         self.is_mine = hs.is_mine
         self.clock = hs.get_clock()
 
+        self._edu_updater = SigningKeyEduUpdater(hs, self)
+
+        federation_registry = hs.get_federation_registry()
+
+        self._is_master = hs.config.worker_app is None
+        if not self._is_master:
+            self._user_device_resync_client = ReplicationUserDevicesResyncRestServlet.make_client(
+                hs
+            )
+        else:
+            # Only register this edu handler on master as it requires writing
+            # device updates to the db
+            #
+            # FIXME: switch to m.signing_key_update when MSC1756 is merged into the spec
+            federation_registry.register_edu_handler(
+                "org.matrix.signing_key_update",
+                self._edu_updater.incoming_signing_key_update,
+            )
+
         # doesn't really work as part of the generic query API, because the
         # query request requires an object POST, but we abuse the
         # "query handler" interface.
-        hs.get_federation_registry().register_query_handler(
+        federation_registry.register_query_handler(
             "client_keys", self.on_federation_query_client_keys
         )
 
     @trace
     @defer.inlineCallbacks
-    def query_devices(self, query_body, timeout):
+    def query_devices(self, query_body, timeout, from_user_id):
         """ Handle a device key query from a client
 
         {
@@ -67,6 +98,11 @@ class E2eKeysHandler(object):
                 }
             }
         }
+
+        Args:
+            from_user_id (str): the user making the query.  This is used when
+                adding cross-signing signatures to limit what signatures users
+                can see.
         """
 
         device_keys_query = query_body.get("device_keys", {})
@@ -105,9 +141,10 @@ class E2eKeysHandler(object):
                 else:
                     query_list.append((user_id, None))
 
-            user_ids_not_in_cache, remote_results = (
-                yield self.store.get_user_devices_from_cache(query_list)
-            )
+            (
+                user_ids_not_in_cache,
+                remote_results,
+            ) = yield self.store.get_user_devices_from_cache(query_list)
             for user_id, devices in iteritems(remote_results):
                 user_devices = results.setdefault(user_id, {})
                 for device_id, device in iteritems(devices):
@@ -125,6 +162,11 @@ class E2eKeysHandler(object):
                 r = remote_queries_not_in_cache.setdefault(domain, {})
                 r[user_id] = remote_queries[user_id]
 
+        # Get cached cross-signing keys
+        cross_signing_keys = yield self.get_cross_signing_keys_from_cache(
+            device_keys_query, from_user_id
+        )
+
         # Now fetch any devices that we don't have in our cache
         @trace
         @defer.inlineCallbacks
@@ -132,8 +174,8 @@ class E2eKeysHandler(object):
             """This is called when we are querying the device list of a user on
             a remote homeserver and their device list is not in the device list
             cache. If we share a room with this user and we're not querying for
-            specific user we will update the cache
-            with their device list."""
+            specific user we will update the cache with their device list.
+            """
 
             destination_query = remote_queries_not_in_cache[destination]
 
@@ -160,12 +202,19 @@ class E2eKeysHandler(object):
                 # probably be tracking their device lists. However, we haven't
                 # done an initial sync on the device list so we do it now.
                 try:
-                    user_devices = yield self.device_handler.device_list_updater.user_device_resync(
-                        user_id
-                    )
+                    if self._is_master:
+                        user_devices = yield self.device_handler.device_list_updater.user_device_resync(
+                            user_id
+                        )
+                    else:
+                        user_devices = yield self._user_device_resync_client(
+                            user_id=user_id
+                        )
+
                     user_devices = user_devices["devices"]
+                    user_results = results.setdefault(user_id, {})
                     for device in user_devices:
-                        results[user_id] = {device["device_id"]: device["keys"]}
+                        user_results[device["device_id"]] = device["keys"]
                     user_ids_updated.append(user_id)
                 except Exception as e:
                     failures[destination] = _exception_to_failure(e)
@@ -188,6 +237,16 @@ class E2eKeysHandler(object):
                     if user_id in destination_query:
                         results[user_id] = keys
 
+                if "master_keys" in remote_result:
+                    for user_id, key in remote_result["master_keys"].items():
+                        if user_id in destination_query:
+                            cross_signing_keys["master_keys"][user_id] = key
+
+                if "self_signing_keys" in remote_result:
+                    for user_id, key in remote_result["self_signing_keys"].items():
+                        if user_id in destination_query:
+                            cross_signing_keys["self_signing_keys"][user_id] = key
+
             except Exception as e:
                 failure = _exception_to_failure(e)
                 failures[destination] = failure
@@ -204,7 +263,58 @@ class E2eKeysHandler(object):
             ).addErrback(unwrapFirstError)
         )
 
-        return {"device_keys": results, "failures": failures}
+        ret = {"device_keys": results, "failures": failures}
+
+        ret.update(cross_signing_keys)
+
+        return ret
+
+    @defer.inlineCallbacks
+    def get_cross_signing_keys_from_cache(self, query, from_user_id):
+        """Get cross-signing keys for users from the database
+
+        Args:
+            query (Iterable[string]) an iterable of user IDs.  A dict whose keys
+                are user IDs satisfies this, so the query format used for
+                query_devices can be used here.
+            from_user_id (str): the user making the query.  This is used when
+                adding cross-signing signatures to limit what signatures users
+                can see.
+
+        Returns:
+            defer.Deferred[dict[str, dict[str, dict]]]: map from
+                (master_keys|self_signing_keys|user_signing_keys) -> user_id -> key
+        """
+        master_keys = {}
+        self_signing_keys = {}
+        user_signing_keys = {}
+
+        user_ids = list(query)
+
+        keys = yield self.store.get_e2e_cross_signing_keys_bulk(user_ids, from_user_id)
+
+        for user_id, user_info in keys.items():
+            if user_info is None:
+                continue
+            if "master" in user_info:
+                master_keys[user_id] = user_info["master"]
+            if "self_signing" in user_info:
+                self_signing_keys[user_id] = user_info["self_signing"]
+
+        if (
+            from_user_id in keys
+            and keys[from_user_id] is not None
+            and "user_signing" in keys[from_user_id]
+        ):
+            # users can see other users' master and self-signing keys, but can
+            # only see their own user-signing keys
+            user_signing_keys[from_user_id] = keys[from_user_id]["user_signing"]
+
+        return {
+            "master_keys": master_keys,
+            "self_signing_keys": self_signing_keys,
+            "user_signing_keys": user_signing_keys,
+        }
 
     @trace
     @defer.inlineCallbacks
@@ -248,16 +358,10 @@ class E2eKeysHandler(object):
 
         results = yield self.store.get_e2e_device_keys(local_query)
 
-        # Build the result structure, un-jsonify the results, and add the
-        # "unsigned" section
+        # Build the result structure
         for user_id, device_keys in results.items():
             for device_id, device_info in device_keys.items():
-                r = dict(device_info["keys"])
-                r["unsigned"] = {}
-                display_name = device_info["device_display_name"]
-                if display_name is not None:
-                    r["unsigned"]["device_display_name"] = display_name
-                result_dict[user_id][device_id] = r
+                result_dict[user_id][device_id] = device_info
 
         log_kv(results)
         return result_dict
@@ -268,7 +372,16 @@ class E2eKeysHandler(object):
         """
         device_keys_query = query_body.get("device_keys", {})
         res = yield self.query_local_devices(device_keys_query)
-        return {"device_keys": res}
+        ret = {"device_keys": res}
+
+        # add in the cross-signing keys
+        cross_signing_keys = yield self.get_cross_signing_keys_from_cache(
+            device_keys_query, None
+        )
+
+        ret.update(cross_signing_keys)
+
+        return ret
 
     @trace
     @defer.inlineCallbacks
@@ -447,8 +560,633 @@ class E2eKeysHandler(object):
         log_kv({"message": "Inserting new one_time_keys.", "keys": new_keys})
         yield self.store.add_e2e_one_time_keys(user_id, device_id, time_now, new_keys)
 
+    @defer.inlineCallbacks
+    def upload_signing_keys_for_user(self, user_id, keys):
+        """Upload signing keys for cross-signing
+
+        Args:
+            user_id (string): the user uploading the keys
+            keys (dict[string, dict]): the signing keys
+        """
+
+        # if a master key is uploaded, then check it.  Otherwise, load the
+        # stored master key, to check signatures on other keys
+        if "master_key" in keys:
+            master_key = keys["master_key"]
+
+            _check_cross_signing_key(master_key, user_id, "master")
+        else:
+            master_key = yield self.store.get_e2e_cross_signing_key(user_id, "master")
+
+        # if there is no master key, then we can't do anything, because all the
+        # other cross-signing keys need to be signed by the master key
+        if not master_key:
+            raise SynapseError(400, "No master key available", Codes.MISSING_PARAM)
+
+        try:
+            master_key_id, master_verify_key = get_verify_key_from_cross_signing_key(
+                master_key
+            )
+        except ValueError:
+            if "master_key" in keys:
+                # the invalid key came from the request
+                raise SynapseError(400, "Invalid master key", Codes.INVALID_PARAM)
+            else:
+                # the invalid key came from the database
+                logger.error("Invalid master key found for user %s", user_id)
+                raise SynapseError(500, "Invalid master key")
+
+        # for the other cross-signing keys, make sure that they have valid
+        # signatures from the master key
+        if "self_signing_key" in keys:
+            self_signing_key = keys["self_signing_key"]
+
+            _check_cross_signing_key(
+                self_signing_key, user_id, "self_signing", master_verify_key
+            )
+
+        if "user_signing_key" in keys:
+            user_signing_key = keys["user_signing_key"]
+
+            _check_cross_signing_key(
+                user_signing_key, user_id, "user_signing", master_verify_key
+            )
+
+        # if everything checks out, then store the keys and send notifications
+        deviceids = []
+        if "master_key" in keys:
+            yield self.store.set_e2e_cross_signing_key(user_id, "master", master_key)
+            deviceids.append(master_verify_key.version)
+        if "self_signing_key" in keys:
+            yield self.store.set_e2e_cross_signing_key(
+                user_id, "self_signing", self_signing_key
+            )
+            try:
+                deviceids.append(
+                    get_verify_key_from_cross_signing_key(self_signing_key)[1].version
+                )
+            except ValueError:
+                raise SynapseError(400, "Invalid self-signing key", Codes.INVALID_PARAM)
+        if "user_signing_key" in keys:
+            yield self.store.set_e2e_cross_signing_key(
+                user_id, "user_signing", user_signing_key
+            )
+            # the signature stream matches the semantics that we want for
+            # user-signing key updates: only the user themselves is notified of
+            # their own user-signing key updates
+            yield self.device_handler.notify_user_signature_update(user_id, [user_id])
+
+        # master key and self-signing key updates match the semantics of device
+        # list updates: all users who share an encrypted room are notified
+        if len(deviceids):
+            yield self.device_handler.notify_device_update(user_id, deviceids)
+
+        return {}
+
+    @defer.inlineCallbacks
+    def upload_signatures_for_device_keys(self, user_id, signatures):
+        """Upload device signatures for cross-signing
+
+        Args:
+            user_id (string): the user uploading the signatures
+            signatures (dict[string, dict[string, dict]]): map of users to
+                devices to signed keys. This is the submission from the user; an
+                exception will be raised if it is malformed.
+        Returns:
+            dict: response to be sent back to the client.  The response will have
+                a "failures" key, which will be a dict mapping users to devices
+                to errors for the signatures that failed.
+        Raises:
+            SynapseError: if the signatures dict is not valid.
+        """
+        failures = {}
+
+        # signatures to be stored.  Each item will be a SignatureListItem
+        signature_list = []
+
+        # split between checking signatures for own user and signatures for
+        # other users, since we verify them with different keys
+        self_signatures = signatures.get(user_id, {})
+        other_signatures = {k: v for k, v in signatures.items() if k != user_id}
+
+        self_signature_list, self_failures = yield self._process_self_signatures(
+            user_id, self_signatures
+        )
+        signature_list.extend(self_signature_list)
+        failures.update(self_failures)
+
+        other_signature_list, other_failures = yield self._process_other_signatures(
+            user_id, other_signatures
+        )
+        signature_list.extend(other_signature_list)
+        failures.update(other_failures)
+
+        # store the signature, and send the appropriate notifications for sync
+        logger.debug("upload signature failures: %r", failures)
+        yield self.store.store_e2e_cross_signing_signatures(user_id, signature_list)
+
+        self_device_ids = [item.target_device_id for item in self_signature_list]
+        if self_device_ids:
+            yield self.device_handler.notify_device_update(user_id, self_device_ids)
+        signed_users = [item.target_user_id for item in other_signature_list]
+        if signed_users:
+            yield self.device_handler.notify_user_signature_update(
+                user_id, signed_users
+            )
+
+        return {"failures": failures}
+
+    @defer.inlineCallbacks
+    def _process_self_signatures(self, user_id, signatures):
+        """Process uploaded signatures of the user's own keys.
+
+        Signatures of the user's own keys from this API come in two forms:
+        - signatures of the user's devices by the user's self-signing key,
+        - signatures of the user's master key by the user's devices.
+
+        Args:
+            user_id (string): the user uploading the keys
+            signatures (dict[string, dict]): map of devices to signed keys
+
+        Returns:
+            (list[SignatureListItem], dict[string, dict[string, dict]]):
+            a list of signatures to store, and a map of users to devices to failure
+            reasons
+
+        Raises:
+            SynapseError: if the input is malformed
+        """
+        signature_list = []
+        failures = {}
+        if not signatures:
+            return signature_list, failures
+
+        if not isinstance(signatures, dict):
+            raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
+
+        try:
+            # get our self-signing key to verify the signatures
+            (
+                _,
+                self_signing_key_id,
+                self_signing_verify_key,
+            ) = yield self._get_e2e_cross_signing_verify_key(user_id, "self_signing")
+
+            # get our master key, since we may have received a signature of it.
+            # We need to fetch it here so that we know what its key ID is, so
+            # that we can check if a signature that was sent is a signature of
+            # the master key or of a device
+            (
+                master_key,
+                _,
+                master_verify_key,
+            ) = yield self._get_e2e_cross_signing_verify_key(user_id, "master")
+
+            # fetch our stored devices.  This is used to 1. verify
+            # signatures on the master key, and 2. to compare with what
+            # was sent if the device was signed
+            devices = yield self.store.get_e2e_device_keys([(user_id, None)])
+
+            if user_id not in devices:
+                raise NotFoundError("No device keys found")
+
+            devices = devices[user_id]
+        except SynapseError as e:
+            failure = _exception_to_failure(e)
+            failures[user_id] = {device: failure for device in signatures.keys()}
+            return signature_list, failures
+
+        for device_id, device in signatures.items():
+            # make sure submitted data is in the right form
+            if not isinstance(device, dict):
+                raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
+
+            try:
+                if "signatures" not in device or user_id not in device["signatures"]:
+                    # no signature was sent
+                    raise SynapseError(
+                        400, "Invalid signature", Codes.INVALID_SIGNATURE
+                    )
+
+                if device_id == master_verify_key.version:
+                    # The signature is of the master key. This needs to be
+                    # handled differently from signatures of normal devices.
+                    master_key_signature_list = self._check_master_key_signature(
+                        user_id, device_id, device, master_key, devices
+                    )
+                    signature_list.extend(master_key_signature_list)
+                    continue
+
+                # at this point, we have a device that should be signed
+                # by the self-signing key
+                if self_signing_key_id not in device["signatures"][user_id]:
+                    # no signature was sent
+                    raise SynapseError(
+                        400, "Invalid signature", Codes.INVALID_SIGNATURE
+                    )
+
+                try:
+                    stored_device = devices[device_id]
+                except KeyError:
+                    raise NotFoundError("Unknown device")
+                if self_signing_key_id in stored_device.get("signatures", {}).get(
+                    user_id, {}
+                ):
+                    # we already have a signature on this device, so we
+                    # can skip it, since it should be exactly the same
+                    continue
+
+                _check_device_signature(
+                    user_id, self_signing_verify_key, device, stored_device
+                )
+
+                signature = device["signatures"][user_id][self_signing_key_id]
+                signature_list.append(
+                    SignatureListItem(
+                        self_signing_key_id, user_id, device_id, signature
+                    )
+                )
+            except SynapseError as e:
+                failures.setdefault(user_id, {})[device_id] = _exception_to_failure(e)
+
+        return signature_list, failures
+
+    def _check_master_key_signature(
+        self, user_id, master_key_id, signed_master_key, stored_master_key, devices
+    ):
+        """Check signatures of a user's master key made by their devices.
+
+        Args:
+            user_id (string): the user whose master key is being checked
+            master_key_id (string): the ID of the user's master key
+            signed_master_key (dict): the user's signed master key that was uploaded
+            stored_master_key (dict): our previously-stored copy of the user's master key
+            devices (iterable(dict)): the user's devices
+
+        Returns:
+            list[SignatureListItem]: a list of signatures to store
+
+        Raises:
+            SynapseError: if a signature is invalid
+        """
+        # for each device that signed the master key, check the signature.
+        master_key_signature_list = []
+        sigs = signed_master_key["signatures"]
+        for signing_key_id, signature in sigs[user_id].items():
+            _, signing_device_id = signing_key_id.split(":", 1)
+            if (
+                signing_device_id not in devices
+                or signing_key_id not in devices[signing_device_id]["keys"]
+            ):
+                # signed by an unknown device, or the
+                # device does not have the key
+                raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE)
+
+            # get the key and check the signature
+            pubkey = devices[signing_device_id]["keys"][signing_key_id]
+            verify_key = decode_verify_key_bytes(signing_key_id, decode_base64(pubkey))
+            _check_device_signature(
+                user_id, verify_key, signed_master_key, stored_master_key
+            )
+
+            master_key_signature_list.append(
+                SignatureListItem(signing_key_id, user_id, master_key_id, signature)
+            )
+
+        return master_key_signature_list
+
+    @defer.inlineCallbacks
+    def _process_other_signatures(self, user_id, signatures):
+        """Process uploaded signatures of other users' keys.  These will be the
+        target user's master keys, signed by the uploading user's user-signing
+        key.
+
+        Args:
+            user_id (string): the user uploading the keys
+            signatures (dict[string, dict]): map of users to devices to signed keys
+
+        Returns:
+            (list[SignatureListItem], dict[string, dict[string, dict]]):
+            a list of signatures to store, and a map of users to devices to failure
+            reasons
+
+        Raises:
+            SynapseError: if the input is malformed
+        """
+        signature_list = []
+        failures = {}
+        if not signatures:
+            return signature_list, failures
+
+        try:
+            # get our user-signing key to verify the signatures
+            (
+                user_signing_key,
+                user_signing_key_id,
+                user_signing_verify_key,
+            ) = yield self._get_e2e_cross_signing_verify_key(user_id, "user_signing")
+        except SynapseError as e:
+            failure = _exception_to_failure(e)
+            for user, devicemap in signatures.items():
+                failures[user] = {device_id: failure for device_id in devicemap.keys()}
+            return signature_list, failures
+
+        for target_user, devicemap in signatures.items():
+            # make sure submitted data is in the right form
+            if not isinstance(devicemap, dict):
+                raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
+            for device in devicemap.values():
+                if not isinstance(device, dict):
+                    raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
+
+            device_id = None
+            try:
+                # get the target user's master key, to make sure it matches
+                # what was sent
+                (
+                    master_key,
+                    master_key_id,
+                    _,
+                ) = yield self._get_e2e_cross_signing_verify_key(
+                    target_user, "master", user_id
+                )
+
+                # make sure that the target user's master key is the one that
+                # was signed (and no others)
+                device_id = master_key_id.split(":", 1)[1]
+                if device_id not in devicemap:
+                    logger.debug(
+                        "upload signature: could not find signature for device %s",
+                        device_id,
+                    )
+                    # set device to None so that the failure gets
+                    # marked on all the signatures
+                    device_id = None
+                    raise NotFoundError("Unknown device")
+                key = devicemap[device_id]
+                other_devices = [k for k in devicemap.keys() if k != device_id]
+                if other_devices:
+                    # other devices were signed -- mark those as failures
+                    logger.debug("upload signature: too many devices specified")
+                    failure = _exception_to_failure(NotFoundError("Unknown device"))
+                    failures[target_user] = {
+                        device: failure for device in other_devices
+                    }
+
+                if user_signing_key_id in master_key.get("signatures", {}).get(
+                    user_id, {}
+                ):
+                    # we already have the signature, so we can skip it
+                    continue
+
+                _check_device_signature(
+                    user_id, user_signing_verify_key, key, master_key
+                )
+
+                signature = key["signatures"][user_id][user_signing_key_id]
+                signature_list.append(
+                    SignatureListItem(
+                        user_signing_key_id, target_user, device_id, signature
+                    )
+                )
+            except SynapseError as e:
+                failure = _exception_to_failure(e)
+                if device_id is None:
+                    failures[target_user] = {
+                        device_id: failure for device_id in devicemap.keys()
+                    }
+                else:
+                    failures.setdefault(target_user, {})[device_id] = failure
+
+        return signature_list, failures
+
+    @defer.inlineCallbacks
+    def _get_e2e_cross_signing_verify_key(
+        self, user_id: str, key_type: str, from_user_id: str = None
+    ):
+        """Fetch locally or remotely query for a cross-signing public key.
+
+        First, attempt to fetch the cross-signing public key from storage.
+        If that fails, query the keys from the homeserver they belong to
+        and update our local copy.
+
+        Args:
+            user_id: the user whose key should be fetched
+            key_type: the type of key to fetch
+            from_user_id: the user that we are fetching the keys for.
+                This affects what signatures are fetched.
+
+        Returns:
+            dict, str, VerifyKey: the raw key data, the key ID, and the
+                signedjson verify key
+
+        Raises:
+            NotFoundError: if the key is not found
+            SynapseError: if `user_id` is invalid
+        """
+        user = UserID.from_string(user_id)
+        key = yield self.store.get_e2e_cross_signing_key(
+            user_id, key_type, from_user_id
+        )
+
+        if key:
+            # We found a copy of this key in our database. Decode and return it
+            key_id, verify_key = get_verify_key_from_cross_signing_key(key)
+            return key, key_id, verify_key
+
+        # If we couldn't find the key locally, and we're looking for keys of
+        # another user then attempt to fetch the missing key from the remote
+        # user's server.
+        #
+        # We may run into this in possible edge cases where a user tries to
+        # cross-sign a remote user, but does not share any rooms with them yet.
+        # Thus, we would not have their key list yet. We instead fetch the key,
+        # store it and notify clients of new, associated device IDs.
+        if self.is_mine(user) or key_type not in ["master", "self_signing"]:
+            # Note that master and self_signing keys are the only cross-signing keys we
+            # can request over federation
+            raise NotFoundError("No %s key found for %s" % (key_type, user_id))
+
+        (
+            key,
+            key_id,
+            verify_key,
+        ) = yield self._retrieve_cross_signing_keys_for_remote_user(user, key_type)
+
+        if key is None:
+            raise NotFoundError("No %s key found for %s" % (key_type, user_id))
+
+        return key, key_id, verify_key
+
+    @defer.inlineCallbacks
+    def _retrieve_cross_signing_keys_for_remote_user(
+        self, user: UserID, desired_key_type: str,
+    ):
+        """Queries cross-signing keys for a remote user and saves them to the database
+
+        Only the key specified by `key_type` will be returned, while all retrieved keys
+        will be saved regardless
+
+        Args:
+            user: The user to query remote keys for
+            desired_key_type: The type of key to receive. One of "master", "self_signing"
+
+        Returns:
+            Deferred[Tuple[Optional[Dict], Optional[str], Optional[VerifyKey]]]: A tuple
+            of the retrieved key content, the key's ID and the matching VerifyKey.
+            If the key cannot be retrieved, all values in the tuple will instead be None.
+        """
+        try:
+            remote_result = yield self.federation.query_user_devices(
+                user.domain, user.to_string()
+            )
+        except Exception as e:
+            logger.warning(
+                "Unable to query %s for cross-signing keys of user %s: %s %s",
+                user.domain,
+                user.to_string(),
+                type(e),
+                e,
+            )
+            return None, None, None
+
+        # Process each of the retrieved cross-signing keys
+        desired_key = None
+        desired_key_id = None
+        desired_verify_key = None
+        retrieved_device_ids = []
+        for key_type in ["master", "self_signing"]:
+            key_content = remote_result.get(key_type + "_key")
+            if not key_content:
+                continue
+
+            # Ensure these keys belong to the correct user
+            if "user_id" not in key_content:
+                logger.warning(
+                    "Invalid %s key retrieved, missing user_id field: %s",
+                    key_type,
+                    key_content,
+                )
+                continue
+            if user.to_string() != key_content["user_id"]:
+                logger.warning(
+                    "Found %s key of user %s when querying for keys of user %s",
+                    key_type,
+                    key_content["user_id"],
+                    user.to_string(),
+                )
+                continue
+
+            # Validate the key contents
+            try:
+                # verify_key is a VerifyKey from signedjson, which uses
+                # .version to denote the portion of the key ID after the
+                # algorithm and colon, which is the device ID
+                key_id, verify_key = get_verify_key_from_cross_signing_key(key_content)
+            except ValueError as e:
+                logger.warning(
+                    "Invalid %s key retrieved: %s - %s %s",
+                    key_type,
+                    key_content,
+                    type(e),
+                    e,
+                )
+                continue
+
+            # Note down the device ID attached to this key
+            retrieved_device_ids.append(verify_key.version)
+
+            # If this is the desired key type, save it and its ID/VerifyKey
+            if key_type == desired_key_type:
+                desired_key = key_content
+                desired_verify_key = verify_key
+                desired_key_id = key_id
+
+            # At the same time, store this key in the db for subsequent queries
+            yield self.store.set_e2e_cross_signing_key(
+                user.to_string(), key_type, key_content
+            )
+
+        # Notify clients that new devices for this user have been discovered
+        if retrieved_device_ids:
+            # XXX is this necessary?
+            yield self.device_handler.notify_device_update(
+                user.to_string(), retrieved_device_ids
+            )
+
+        return desired_key, desired_key_id, desired_verify_key
+
+
+def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
+    """Check a cross-signing key uploaded by a user.  Performs some basic sanity
+    checking, and ensures that it is signed, if a signature is required.
+
+    Args:
+        key (dict): the key data to verify
+        user_id (str): the user whose key is being checked
+        key_type (str): the type of key that the key should be
+        signing_key (VerifyKey): (optional) the signing key that the key should
+            be signed with.  If omitted, signatures will not be checked.
+    """
+    if (
+        key.get("user_id") != user_id
+        or key_type not in key.get("usage", [])
+        or len(key.get("keys", {})) != 1
+    ):
+        raise SynapseError(400, ("Invalid %s key" % (key_type,)), Codes.INVALID_PARAM)
+
+    if signing_key:
+        try:
+            verify_signed_json(key, user_id, signing_key)
+        except SignatureVerifyException:
+            raise SynapseError(
+                400, ("Invalid signature on %s key" % key_type), Codes.INVALID_SIGNATURE
+            )
+
+
+def _check_device_signature(user_id, verify_key, signed_device, stored_device):
+    """Check that a signature on a device or cross-signing key is correct and
+    matches the copy of the device/key that we have stored.  Throws an
+    exception if an error is detected.
+
+    Args:
+        user_id (str): the user ID whose signature is being checked
+        verify_key (VerifyKey): the key to verify the device with
+        signed_device (dict): the uploaded signed device data
+        stored_device (dict): our previously stored copy of the device
+
+    Raises:
+        SynapseError: if the signature was invalid or the sent device is not the
+            same as the stored device
+
+    """
+
+    # make sure that the device submitted matches what we have stored
+    stripped_signed_device = {
+        k: v for k, v in signed_device.items() if k not in ["signatures", "unsigned"]
+    }
+    stripped_stored_device = {
+        k: v for k, v in stored_device.items() if k not in ["signatures", "unsigned"]
+    }
+    if stripped_signed_device != stripped_stored_device:
+        logger.debug(
+            "upload signatures: key does not match %s vs %s",
+            signed_device,
+            stored_device,
+        )
+        raise SynapseError(400, "Key does not match")
+
+    try:
+        verify_signed_json(signed_device, user_id, verify_key)
+    except SignatureVerifyException:
+        logger.debug("invalid signature on key")
+        raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE)
+
 
 def _exception_to_failure(e):
+    if isinstance(e, SynapseError):
+        return {"status": e.code, "errcode": e.errcode, "message": str(e)}
+
     if isinstance(e, CodeMessageException):
         return {"status": e.code, "message": str(e)}
 
@@ -476,3 +1214,99 @@ def _one_time_keys_match(old_key_json, new_key):
     new_key_copy.pop("signatures", None)
 
     return old_key == new_key_copy
+
+
+@attr.s
+class SignatureListItem:
+    """An item in the signature list as used by upload_signatures_for_device_keys.
+    """
+
+    signing_key_id = attr.ib()
+    target_user_id = attr.ib()
+    target_device_id = attr.ib()
+    signature = attr.ib()
+
+
+class SigningKeyEduUpdater(object):
+    """Handles incoming signing key updates from federation and updates the DB"""
+
+    def __init__(self, hs, e2e_keys_handler):
+        self.store = hs.get_datastore()
+        self.federation = hs.get_federation_client()
+        self.clock = hs.get_clock()
+        self.e2e_keys_handler = e2e_keys_handler
+
+        self._remote_edu_linearizer = Linearizer(name="remote_signing_key")
+
+        # user_id -> list of updates waiting to be handled.
+        self._pending_updates = {}
+
+        # Recently seen stream ids. We don't bother keeping these in the DB,
+        # but they're useful to have them about to reduce the number of spurious
+        # resyncs.
+        self._seen_updates = ExpiringCache(
+            cache_name="signing_key_update_edu",
+            clock=self.clock,
+            max_len=10000,
+            expiry_ms=30 * 60 * 1000,
+            iterable=True,
+        )
+
+    @defer.inlineCallbacks
+    def incoming_signing_key_update(self, origin, edu_content):
+        """Called on incoming signing key update from federation. Responsible for
+        parsing the EDU and adding to pending updates list.
+
+        Args:
+            origin (string): the server that sent the EDU
+            edu_content (dict): the contents of the EDU
+        """
+
+        user_id = edu_content.pop("user_id")
+        master_key = edu_content.pop("master_key", None)
+        self_signing_key = edu_content.pop("self_signing_key", None)
+
+        if get_domain_from_id(user_id) != origin:
+            logger.warning("Got signing key update edu for %r from %r", user_id, origin)
+            return
+
+        room_ids = yield self.store.get_rooms_for_user(user_id)
+        if not room_ids:
+            # We don't share any rooms with this user. Ignore update, as we
+            # probably won't get any further updates.
+            return
+
+        self._pending_updates.setdefault(user_id, []).append(
+            (master_key, self_signing_key)
+        )
+
+        yield self._handle_signing_key_updates(user_id)
+
+    @defer.inlineCallbacks
+    def _handle_signing_key_updates(self, user_id):
+        """Actually handle pending updates.
+
+        Args:
+            user_id (string): the user whose updates we are processing
+        """
+
+        device_handler = self.e2e_keys_handler.device_handler
+        device_list_updater = device_handler.device_list_updater
+
+        with (yield self._remote_edu_linearizer.queue(user_id)):
+            pending_updates = self._pending_updates.pop(user_id, [])
+            if not pending_updates:
+                # This can happen since we batch updates
+                return
+
+            device_ids = []
+
+            logger.info("pending updates: %r", pending_updates)
+
+            for master_key, self_signing_key in pending_updates:
+                new_device_ids = yield device_list_updater.process_cross_signing_key_update(
+                    user_id, master_key, self_signing_key,
+                )
+                device_ids = device_ids + new_device_ids
+
+            yield device_handler.notify_device_update(user_id, device_ids)
diff --git a/synapse/handlers/e2e_room_keys.py b/synapse/handlers/e2e_room_keys.py
index a9d80f708c..9abaf13b8f 100644
--- a/synapse/handlers/e2e_room_keys.py
+++ b/synapse/handlers/e2e_room_keys.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2017, 2018 New Vector Ltd
+# Copyright 2019 Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -103,14 +104,35 @@ class E2eRoomKeysHandler(object):
                 rooms
             session_id(string): session ID to delete keys for, for None to delete keys
                 for all sessions
+        Raises:
+            NotFoundError: if the backup version does not exist
         Returns:
-            A deferred of the deletion transaction
+            A dict containing the count and etag for the backup version
         """
 
         # lock for consistency with uploading
         with (yield self._upload_linearizer.queue(user_id)):
+            # make sure the backup version exists
+            try:
+                version_info = yield self.store.get_e2e_room_keys_version_info(
+                    user_id, version
+                )
+            except StoreError as e:
+                if e.code == 404:
+                    raise NotFoundError("Unknown backup version")
+                else:
+                    raise
+
             yield self.store.delete_e2e_room_keys(user_id, version, room_id, session_id)
 
+            version_etag = version_info["etag"] + 1
+            yield self.store.update_e2e_room_keys_version(
+                user_id, version, None, version_etag
+            )
+
+            count = yield self.store.count_e2e_room_keys(user_id, version)
+            return {"etag": str(version_etag), "count": count}
+
     @trace
     @defer.inlineCallbacks
     def upload_room_keys(self, user_id, version, room_keys):
@@ -138,6 +160,9 @@ class E2eRoomKeysHandler(object):
             }
         }
 
+        Returns:
+            A dict containing the count and etag for the backup version
+
         Raises:
             NotFoundError: if there are no versions defined
             RoomKeysVersionError: if the uploaded version is not the current version
@@ -171,59 +196,69 @@ class E2eRoomKeysHandler(object):
                     else:
                         raise
 
-            # go through the room_keys.
-            # XXX: this should/could be done concurrently, given we're in a lock.
+            # Fetch any existing room keys for the sessions that have been
+            # submitted.  Then compare them with the submitted keys.  If the
+            # key is new, insert it; if the key should be updated, then update
+            # it; otherwise, drop it.
+            existing_keys = yield self.store.get_e2e_room_keys_multi(
+                user_id, version, room_keys["rooms"]
+            )
+            to_insert = []  # batch the inserts together
+            changed = False  # if anything has changed, we need to update the etag
             for room_id, room in iteritems(room_keys["rooms"]):
-                for session_id, session in iteritems(room["sessions"]):
-                    yield self._upload_room_key(
-                        user_id, version, room_id, session_id, session
+                for session_id, room_key in iteritems(room["sessions"]):
+                    if not isinstance(room_key["is_verified"], bool):
+                        msg = (
+                            "is_verified must be a boolean in keys for session %s in"
+                            "room %s" % (session_id, room_id)
+                        )
+                        raise SynapseError(400, msg, Codes.INVALID_PARAM)
+
+                    log_kv(
+                        {
+                            "message": "Trying to upload room key",
+                            "room_id": room_id,
+                            "session_id": session_id,
+                            "user_id": user_id,
+                        }
                     )
-
-    @defer.inlineCallbacks
-    def _upload_room_key(self, user_id, version, room_id, session_id, room_key):
-        """Upload a given room_key for a given room and session into a given
-        version of the backup.  Merges the key with any which might already exist.
-
-        Args:
-            user_id(str): the user whose backup we're setting
-            version(str): the version ID of the backup we're updating
-            room_id(str): the ID of the room whose keys we're setting
-            session_id(str): the session whose room_key we're setting
-            room_key(dict): the room_key being set
-        """
-        log_kv(
-            {
-                "message": "Trying to upload room key",
-                "room_id": room_id,
-                "session_id": session_id,
-                "user_id": user_id,
-            }
-        )
-        # get the room_key for this particular row
-        current_room_key = None
-        try:
-            current_room_key = yield self.store.get_e2e_room_key(
-                user_id, version, room_id, session_id
-            )
-        except StoreError as e:
-            if e.code == 404:
-                log_kv(
-                    {
-                        "message": "Room key not found.",
-                        "room_id": room_id,
-                        "user_id": user_id,
-                    }
+                    current_room_key = existing_keys.get(room_id, {}).get(session_id)
+                    if current_room_key:
+                        if self._should_replace_room_key(current_room_key, room_key):
+                            log_kv({"message": "Replacing room key."})
+                            # updates are done one at a time in the DB, so send
+                            # updates right away rather than batching them up,
+                            # like we do with the inserts
+                            yield self.store.update_e2e_room_key(
+                                user_id, version, room_id, session_id, room_key
+                            )
+                            changed = True
+                        else:
+                            log_kv({"message": "Not replacing room_key."})
+                    else:
+                        log_kv(
+                            {
+                                "message": "Room key not found.",
+                                "room_id": room_id,
+                                "user_id": user_id,
+                            }
+                        )
+                        log_kv({"message": "Replacing room key."})
+                        to_insert.append((room_id, session_id, room_key))
+                        changed = True
+
+            if len(to_insert):
+                yield self.store.add_e2e_room_keys(user_id, version, to_insert)
+
+            version_etag = version_info["etag"]
+            if changed:
+                version_etag = version_etag + 1
+                yield self.store.update_e2e_room_keys_version(
+                    user_id, version, None, version_etag
                 )
-            else:
-                raise
 
-        if self._should_replace_room_key(current_room_key, room_key):
-            log_kv({"message": "Replacing room key."})
-            yield self.store.set_e2e_room_key(
-                user_id, version, room_id, session_id, room_key
-            )
-        else:
-            log_kv({"message": "Not replacing room_key."})
+            count = yield self.store.count_e2e_room_keys(user_id, version)
+            return {"etag": str(version_etag), "count": count}
 
     @staticmethod
     def _should_replace_room_key(current_room_key, room_key):
@@ -314,6 +349,8 @@ class E2eRoomKeysHandler(object):
                     raise NotFoundError("Unknown backup version")
                 else:
                     raise
+
+            res["count"] = yield self.store.count_e2e_room_keys(user_id, res["version"])
             return res
 
     @trace
@@ -352,8 +389,8 @@ class E2eRoomKeysHandler(object):
             A deferred of an empty dict.
         """
         if "version" not in version_info:
-            raise SynapseError(400, "Missing version in body", Codes.MISSING_PARAM)
-        if version_info["version"] != version:
+            version_info["version"] = version
+        elif version_info["version"] != version:
             raise SynapseError(
                 400, "Version in body does not match", Codes.INVALID_PARAM
             )
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index 5e748687e3..71a89f09c7 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -16,11 +16,10 @@
 import logging
 import random
 
-from twisted.internet import defer
-
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import AuthError, SynapseError
 from synapse.events import EventBase
+from synapse.handlers.presence import format_user_presence_state
 from synapse.logging.utils import log_function
 from synapse.types import UserID
 from synapse.visibility import filter_events_for_client
@@ -50,9 +49,8 @@ class EventStreamHandler(BaseHandler):
         self._server_notices_sender = hs.get_server_notices_sender()
         self._event_serializer = hs.get_event_client_serializer()
 
-    @defer.inlineCallbacks
     @log_function
-    def get_stream(
+    async def get_stream(
         self,
         auth_user_id,
         pagin_config,
@@ -69,17 +67,17 @@ class EventStreamHandler(BaseHandler):
         """
 
         if room_id:
-            blocked = yield self.store.is_room_blocked(room_id)
+            blocked = await self.store.is_room_blocked(room_id)
             if blocked:
                 raise SynapseError(403, "This room has been blocked on this server")
 
         # send any outstanding server notices to the user.
-        yield self._server_notices_sender.on_user_syncing(auth_user_id)
+        await self._server_notices_sender.on_user_syncing(auth_user_id)
 
         auth_user = UserID.from_string(auth_user_id)
         presence_handler = self.hs.get_presence_handler()
 
-        context = yield presence_handler.user_syncing(
+        context = await presence_handler.user_syncing(
             auth_user_id, affect_presence=affect_presence
         )
         with context:
@@ -91,7 +89,7 @@ class EventStreamHandler(BaseHandler):
                 # thundering herds on restart.
                 timeout = random.randint(int(timeout * 0.9), int(timeout * 1.1))
 
-            events, tokens = yield self.notifier.get_events_for(
+            events, tokens = await self.notifier.get_events_for(
                 auth_user,
                 pagin_config,
                 timeout,
@@ -100,6 +98,8 @@ class EventStreamHandler(BaseHandler):
                 explicit_room_id=room_id,
             )
 
+            time_now = self.clock.time_msec()
+
             # When the user joins a new room, or another user joins a currently
             # joined room, we need to send down presence for those users.
             to_add = []
@@ -112,23 +112,24 @@ class EventStreamHandler(BaseHandler):
                     # Send down presence.
                     if event.state_key == auth_user_id:
                         # Send down presence for everyone in the room.
-                        users = yield self.state.get_current_users_in_room(
+                        users = await self.state.get_current_users_in_room(
                             event.room_id
                         )
-                        states = yield presence_handler.get_states(users, as_event=True)
-                        to_add.extend(states)
                     else:
+                        users = [event.state_key]
 
-                        ev = yield presence_handler.get_state(
-                            UserID.from_string(event.state_key), as_event=True
-                        )
-                        to_add.append(ev)
+                    states = await presence_handler.get_states(users)
+                    to_add.extend(
+                        {
+                            "type": EventTypes.Presence,
+                            "content": format_user_presence_state(state, time_now),
+                        }
+                        for state in states
+                    )
 
             events.extend(to_add)
 
-            time_now = self.clock.time_msec()
-
-            chunks = yield self._event_serializer.serialize_events(
+            chunks = await self._event_serializer.serialize_events(
                 events,
                 time_now,
                 as_client_event=as_client_event,
@@ -147,8 +148,11 @@ class EventStreamHandler(BaseHandler):
 
 
 class EventHandler(BaseHandler):
-    @defer.inlineCallbacks
-    def get_event(self, user, room_id, event_id):
+    def __init__(self, hs):
+        super(EventHandler, self).__init__(hs)
+        self.storage = hs.get_storage()
+
+    async def get_event(self, user, room_id, event_id):
         """Retrieve a single specified event.
 
         Args:
@@ -163,16 +167,16 @@ class EventHandler(BaseHandler):
             AuthError if the user does not have the rights to inspect this
             event.
         """
-        event = yield self.store.get_event(event_id, check_room_id=room_id)
+        event = await self.store.get_event(event_id, check_room_id=room_id)
 
         if not event:
             return None
 
-        users = yield self.store.get_users_in_room(event.room_id)
+        users = await self.store.get_users_in_room(event.room_id)
         is_peeking = user.to_string() not in users
 
-        filtered = yield filter_events_for_client(
-            self.store, user.to_string(), [event], is_peeking=is_peeking
+        filtered = await filter_events_for_client(
+            self.storage, user.to_string(), [event], is_peeking=is_peeking
         )
 
         if not filtered:
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index f72b81d419..3e60774b33 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -19,17 +19,20 @@
 
 import itertools
 import logging
+from typing import Dict, Iterable, List, Optional, Sequence, Tuple
 
 import six
 from six import iteritems, itervalues
 from six.moves import http_client, zip
 
+import attr
 from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import verify_signed_json
 from unpaddedbase64 import decode_base64
 
 from twisted.internet import defer
 
+from synapse import event_auth
 from synapse.api.constants import EventTypes, Membership, RejectedReason
 from synapse.api.errors import (
     AuthError,
@@ -37,14 +40,17 @@ from synapse.api.errors import (
     Codes,
     FederationDeniedError,
     FederationError,
+    HttpResponseException,
     RequestSendFailed,
-    StoreError,
     SynapseError,
 )
-from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersions
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion, RoomVersions
 from synapse.crypto.event_signing import compute_event_signature
 from synapse.event_auth import auth_types_for_event
+from synapse.events import EventBase
+from synapse.events.snapshot import EventContext
 from synapse.events.validator import EventValidator
+from synapse.handlers._base import BaseHandler
 from synapse.logging.context import (
     make_deferred_yieldable,
     nested_logging_context,
@@ -52,52 +58,49 @@ from synapse.logging.context import (
     run_in_background,
 )
 from synapse.logging.utils import log_function
+from synapse.replication.http.devices import ReplicationUserDevicesResyncRestServlet
 from synapse.replication.http.federation import (
     ReplicationCleanRoomRestServlet,
     ReplicationFederationSendEventsRestServlet,
+    ReplicationStoreRoomOnInviteRestServlet,
 )
 from synapse.replication.http.membership import ReplicationUserJoinedLeftRoomRestServlet
 from synapse.state import StateResolutionStore, resolve_events_with_store
-from synapse.types import UserID, get_domain_from_id
-from synapse.util import unwrapFirstError
-from synapse.util.async_helpers import Linearizer
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
+from synapse.types import JsonDict, StateMap, UserID, get_domain_from_id
+from synapse.util.async_helpers import Linearizer, concurrently_execute
 from synapse.util.distributor import user_joined_room
 from synapse.util.retryutils import NotRetryingDestination
+from synapse.util.stringutils import shortstr
 from synapse.visibility import filter_events_for_server
 
-from ._base import BaseHandler
-
 logger = logging.getLogger(__name__)
 
 
-def shortstr(iterable, maxitems=5):
-    """If iterable has maxitems or fewer, return the stringification of a list
-    containing those items.
+@attr.s
+class _NewEventInfo:
+    """Holds information about a received event, ready for passing to _handle_new_events
 
-    Otherwise, return the stringification of a a list with the first maxitems items,
-    followed by "...".
+    Attributes:
+        event: the received event
 
-    Args:
-        iterable (Iterable): iterable to truncate
-        maxitems (int): number of items to return before truncating
+        state: the state at that event
 
-    Returns:
-        unicode
+        auth_events: the auth_event map for that event
     """
 
-    items = list(itertools.islice(iterable, maxitems + 1))
-    if len(items) <= maxitems:
-        return str(items)
-    return "[" + ", ".join(repr(r) for r in items[:maxitems]) + ", ...]"
+    event = attr.ib(type=EventBase)
+    state = attr.ib(type=Optional[Sequence[EventBase]], default=None)
+    auth_events = attr.ib(type=Optional[StateMap[EventBase]], default=None)
 
 
 class FederationHandler(BaseHandler):
     """Handles events that originated from federation.
         Responsible for:
         a) handling received Pdus before handing them on as Events to the rest
-        of the home server (including auth and state conflict resoultion)
+        of the homeserver (including auth and state conflict resoultion)
         b) converting events that were produced by local clients that may need
-        to be sent to remote home servers.
+        to be sent to remote homeservers.
         c) doing the necessary dances to invite remote users and join remote
         rooms.
     """
@@ -108,6 +111,8 @@ class FederationHandler(BaseHandler):
         self.hs = hs
 
         self.store = hs.get_datastore()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
         self.federation_client = hs.get_federation_client()
         self.state_handler = hs.get_state_handler()
         self.server_name = hs.hostname
@@ -117,13 +122,14 @@ class FederationHandler(BaseHandler):
         self.pusher_pool = hs.get_pusherpool()
         self.spam_checker = hs.get_spam_checker()
         self.event_creation_handler = hs.get_event_creation_handler()
+        self._message_handler = hs.get_message_handler()
         self._server_notices_mxid = hs.config.server_notices_mxid
         self.config = hs.config
         self.http_client = hs.get_simple_http_client()
+        self._instance_name = hs.get_instance_name()
+        self._replication = hs.get_replication_data_handler()
 
-        self._send_events_to_master = ReplicationFederationSendEventsRestServlet.make_client(
-            hs
-        )
+        self._send_events = ReplicationFederationSendEventsRestServlet.make_client(hs)
         self._notify_user_membership_change = ReplicationUserJoinedLeftRoomRestServlet.make_client(
             hs
         )
@@ -131,14 +137,26 @@ class FederationHandler(BaseHandler):
             hs
         )
 
+        if hs.config.worker_app:
+            self._user_device_resync = ReplicationUserDevicesResyncRestServlet.make_client(
+                hs
+            )
+            self._maybe_store_room_on_invite = ReplicationStoreRoomOnInviteRestServlet.make_client(
+                hs
+            )
+        else:
+            self._device_list_updater = hs.get_device_handler().device_list_updater
+            self._maybe_store_room_on_invite = self.store.maybe_store_room_on_invite
+
         # When joining a room we need to queue any events for that room up
         self.room_queues = {}
         self._room_pdu_linearizer = Linearizer("fed_room_pdu")
 
         self.third_party_event_rules = hs.get_third_party_event_rules()
 
-    @defer.inlineCallbacks
-    def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False):
+        self._ephemeral_messages_enabled = hs.config.enable_ephemeral_messages
+
+    async def on_receive_pdu(self, origin, pdu, sent_to_us_directly=False) -> None:
         """ Process a PDU received via a federation /send/ transaction, or
         via backfill of missing prev_events
 
@@ -148,17 +166,15 @@ class FederationHandler(BaseHandler):
             pdu (FrozenEvent): received PDU
             sent_to_us_directly (bool): True if this event was pushed to us; False if
                 we pulled it as the result of a missing prev_event.
-
-        Returns (Deferred): completes with None
         """
 
         room_id = pdu.room_id
         event_id = pdu.event_id
 
-        logger.info("[%s %s] handling received PDU: %s", room_id, event_id, pdu)
+        logger.info("handling received PDU: %s", pdu)
 
         # We reprocess pdus when we have seen them only as outliers
-        existing = yield self.store.get_event(
+        existing = await self.store.get_event(
             event_id, allow_none=True, allow_rejected=True
         )
 
@@ -179,7 +195,7 @@ class FederationHandler(BaseHandler):
         try:
             self._sanity_check_event(pdu)
         except SynapseError as err:
-            logger.warn(
+            logger.warning(
                 "[%s %s] Received event failed sanity checks", room_id, event_id
             )
             raise FederationError("ERROR", err.code, err.msg, affected=pdu.event_id)
@@ -202,7 +218,7 @@ class FederationHandler(BaseHandler):
         #
         # Note that if we were never in the room then we would have already
         # dropped the event, since we wouldn't know the room version.
-        is_in_room = yield self.auth.check_host_in_room(room_id, self.server_name)
+        is_in_room = await self.auth.check_host_in_room(room_id, self.server_name)
         if not is_in_room:
             logger.info(
                 "[%s %s] Ignoring PDU from %s as we're not in the room",
@@ -213,25 +229,24 @@ class FederationHandler(BaseHandler):
             return None
 
         state = None
-        auth_chain = []
 
         # Get missing pdus if necessary.
         if not pdu.internal_metadata.is_outlier():
             # We only backfill backwards to the min depth.
-            min_depth = yield self.get_min_depth_for_context(pdu.room_id)
+            min_depth = await self.get_min_depth_for_context(pdu.room_id)
 
             logger.debug("[%s %s] min_depth: %d", room_id, event_id, min_depth)
 
             prevs = set(pdu.prev_event_ids())
-            seen = yield self.store.have_seen_events(prevs)
+            seen = await self.store.have_seen_events(prevs)
 
-            if min_depth and pdu.depth < min_depth:
+            if min_depth is not None and pdu.depth < min_depth:
                 # This is so that we don't notify the user about this
                 # message, to work around the fact that some events will
                 # reference really really old events we really don't want to
                 # send to the clients.
                 pdu.internal_metadata.outlier = True
-            elif min_depth and pdu.depth > min_depth:
+            elif min_depth is not None and pdu.depth > min_depth:
                 missing_prevs = prevs - seen
                 if sent_to_us_directly and missing_prevs:
                     # If we're missing stuff, ensure we only fetch stuff one
@@ -243,7 +258,7 @@ class FederationHandler(BaseHandler):
                         len(missing_prevs),
                         shortstr(missing_prevs),
                     )
-                    with (yield self._room_pdu_linearizer.queue(pdu.room_id)):
+                    with (await self._room_pdu_linearizer.queue(pdu.room_id)):
                         logger.info(
                             "[%s %s] Acquired room lock to fetch %d missing prev_events",
                             room_id,
@@ -251,13 +266,19 @@ class FederationHandler(BaseHandler):
                             len(missing_prevs),
                         )
 
-                        yield self._get_missing_events_for_pdu(
-                            origin, pdu, prevs, min_depth
-                        )
+                        try:
+                            await self._get_missing_events_for_pdu(
+                                origin, pdu, prevs, min_depth
+                            )
+                        except Exception as e:
+                            raise Exception(
+                                "Error fetching missing prev_events for %s: %s"
+                                % (event_id, e)
+                            )
 
                         # Update the set of things we've seen after trying to
                         # fetch the missing stuff
-                        seen = yield self.store.have_seen_events(prevs)
+                        seen = await self.store.have_seen_events(prevs)
 
                         if not prevs - seen:
                             logger.info(
@@ -265,14 +286,6 @@ class FederationHandler(BaseHandler):
                                 room_id,
                                 event_id,
                             )
-                elif missing_prevs:
-                    logger.info(
-                        "[%s %s] Not recursively fetching %d missing prev_events: %s",
-                        room_id,
-                        event_id,
-                        len(missing_prevs),
-                        shortstr(missing_prevs),
-                    )
 
             if prevs - seen:
                 # We've still not been able to get all of the prev_events for this event.
@@ -300,7 +313,7 @@ class FederationHandler(BaseHandler):
                 # following.
 
                 if sent_to_us_directly:
-                    logger.warn(
+                    logger.warning(
                         "[%s %s] Rejecting: failed to fetch %d prev events: %s",
                         room_id,
                         event_id,
@@ -317,18 +330,21 @@ class FederationHandler(BaseHandler):
                         affected=pdu.event_id,
                     )
 
+                logger.info(
+                    "Event %s is missing prev_events: calculating state for a "
+                    "backwards extremity",
+                    event_id,
+                )
+
                 # Calculate the state after each of the previous events, and
                 # resolve them to find the correct state at the current event.
-                auth_chains = set()
                 event_map = {event_id: pdu}
                 try:
                     # Get the state of the events we know about
-                    ours = yield self.store.get_state_groups_ids(room_id, seen)
+                    ours = await self.state_store.get_state_groups_ids(room_id, seen)
 
                     # state_maps is a list of mappings from (type, state_key) to event_id
-                    state_maps = list(
-                        ours.values()
-                    )  # type: list[dict[tuple[str, str], str]]
+                    state_maps = list(ours.values())  # type: List[StateMap[str]]
 
                     # we don't need this any more, let's delete it.
                     del ours
@@ -337,43 +353,17 @@ class FederationHandler(BaseHandler):
                     # know about
                     for p in prevs - seen:
                         logger.info(
-                            "[%s %s] Requesting state at missing prev_event %s",
-                            room_id,
-                            event_id,
-                            p,
+                            "Requesting state at missing prev_event %s", event_id,
                         )
 
-                        room_version = yield self.store.get_room_version(room_id)
-
                         with nested_logging_context(p):
                             # note that if any of the missing prevs share missing state or
                             # auth events, the requests to fetch those events are deduped
                             # by the get_pdu_cache in federation_client.
-                            remote_state, got_auth_chain = (
-                                yield self.federation_client.get_state_for_room(
-                                    origin, room_id, p
-                                )
+                            (remote_state, _,) = await self._get_state_for_room(
+                                origin, room_id, p, include_event_in_state=True
                             )
 
-                            # we want the state *after* p; get_state_for_room returns the
-                            # state *before* p.
-                            remote_event = yield self.federation_client.get_pdu(
-                                [origin], p, room_version, outlier=True
-                            )
-
-                            if remote_event is None:
-                                raise Exception(
-                                    "Unable to get missing prev_event %s" % (p,)
-                                )
-
-                            if remote_event.is_state():
-                                remote_state.append(remote_event)
-
-                            # XXX hrm I'm not convinced that duplicate events will compare
-                            # for equality, so I'm not sure this does what the author
-                            # hoped.
-                            auth_chains.update(got_auth_chain)
-
                             remote_state_map = {
                                 (x.type, x.state_key): x.event_id for x in remote_state
                             }
@@ -382,7 +372,9 @@ class FederationHandler(BaseHandler):
                             for x in remote_state:
                                 event_map[x.event_id] = x
 
-                    state_map = yield resolve_events_with_store(
+                    room_version = await self.store.get_room_version_id(room_id)
+                    state_map = await resolve_events_with_store(
+                        room_id,
                         room_version,
                         state_maps,
                         event_map,
@@ -394,17 +386,16 @@ class FederationHandler(BaseHandler):
 
                     # First though we need to fetch all the events that are in
                     # state_map, so we can build up the state below.
-                    evs = yield self.store.get_events(
+                    evs = await self.store.get_events(
                         list(state_map.values()),
                         get_prev_content=False,
-                        check_redacted=False,
+                        redact_behaviour=EventRedactBehaviour.AS_IS,
                     )
                     event_map.update(evs)
 
                     state = [event_map[e] for e in six.itervalues(state_map)]
-                    auth_chain = list(auth_chains)
                 except Exception:
-                    logger.warn(
+                    logger.warning(
                         "[%s %s] Error attempting to resolve state at missing "
                         "prev_events",
                         room_id,
@@ -418,12 +409,9 @@ class FederationHandler(BaseHandler):
                         affected=event_id,
                     )
 
-        yield self._process_received_pdu(
-            origin, pdu, state=state, auth_chain=auth_chain
-        )
+        await self._process_received_pdu(origin, pdu, state=state)
 
-    @defer.inlineCallbacks
-    def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
+    async def _get_missing_events_for_pdu(self, origin, pdu, prevs, min_depth):
         """
         Args:
             origin (str): Origin of the pdu. Will be called to get the missing events
@@ -435,12 +423,12 @@ class FederationHandler(BaseHandler):
         room_id = pdu.room_id
         event_id = pdu.event_id
 
-        seen = yield self.store.have_seen_events(prevs)
+        seen = await self.store.have_seen_events(prevs)
 
         if not prevs - seen:
             return
 
-        latest = yield self.store.get_latest_event_ids_in_room(room_id)
+        latest = await self.store.get_latest_event_ids_in_room(room_id)
 
         # We add the prev events that we have seen to the latest
         # list to ensure the remote server doesn't give them to us
@@ -504,7 +492,7 @@ class FederationHandler(BaseHandler):
         # All that said: Let's try increasing the timout to 60s and see what happens.
 
         try:
-            missing_events = yield self.federation_client.get_missing_events(
+            missing_events = await self.federation_client.get_missing_events(
                 origin,
                 room_id,
                 earliest_events_ids=list(latest),
@@ -513,11 +501,13 @@ class FederationHandler(BaseHandler):
                 min_depth=min_depth,
                 timeout=60000,
             )
-        except RequestSendFailed as e:
+        except (RequestSendFailed, HttpResponseException, NotRetryingDestination) as e:
             # We failed to get the missing events, but since we need to handle
             # the case of `get_missing_events` not returning the necessary
             # events anyway, it is safe to simply log the error and continue.
-            logger.warn("[%s %s]: Failed to get prev_events: %s", room_id, event_id, e)
+            logger.warning(
+                "[%s %s]: Failed to get prev_events: %s", room_id, event_id, e
+            )
             return
 
         logger.info(
@@ -541,10 +531,10 @@ class FederationHandler(BaseHandler):
             )
             with nested_logging_context(ev.event_id):
                 try:
-                    yield self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
+                    await self.on_receive_pdu(origin, ev, sent_to_us_directly=False)
                 except FederationError as e:
                     if e.code == 403:
-                        logger.warn(
+                        logger.warning(
                             "[%s %s] Received prev_event %s failed history check.",
                             room_id,
                             event_id,
@@ -553,66 +543,154 @@ class FederationHandler(BaseHandler):
                     else:
                         raise
 
-    @defer.inlineCallbacks
-    def _process_received_pdu(self, origin, event, state, auth_chain):
-        """ Called when we have a new pdu. We need to do auth checks and put it
-        through the StateHandler.
+    async def _get_state_for_room(
+        self,
+        destination: str,
+        room_id: str,
+        event_id: str,
+        include_event_in_state: bool = False,
+    ) -> Tuple[List[EventBase], List[EventBase]]:
+        """Requests all of the room state at a given event from a remote homeserver.
+
+        Args:
+            destination: The remote homeserver to query for the state.
+            room_id: The id of the room we're interested in.
+            event_id: The id of the event we want the state at.
+            include_event_in_state: if true, the event itself will be included in the
+                returned state event list.
+
+        Returns:
+            A list of events in the state, possibly including the event itself, and
+            a list of events in the auth chain for the given event.
         """
-        room_id = event.room_id
-        event_id = event.event_id
+        (
+            state_event_ids,
+            auth_event_ids,
+        ) = await self.federation_client.get_room_state_ids(
+            destination, room_id, event_id=event_id
+        )
 
-        logger.debug("[%s %s] Processing event: %s", room_id, event_id, event)
+        desired_events = set(state_event_ids + auth_event_ids)
 
-        event_ids = set()
-        if state:
-            event_ids |= {e.event_id for e in state}
-        if auth_chain:
-            event_ids |= {e.event_id for e in auth_chain}
+        if include_event_in_state:
+            desired_events.add(event_id)
 
-        seen_ids = yield self.store.have_seen_events(event_ids)
+        event_map = await self._get_events_from_store_or_dest(
+            destination, room_id, desired_events
+        )
 
-        if state and auth_chain is not None:
-            # If we have any state or auth_chain given to us by the replication
-            # layer, then we should handle them (if we haven't before.)
+        failed_to_fetch = desired_events - event_map.keys()
+        if failed_to_fetch:
+            logger.warning(
+                "Failed to fetch missing state/auth events for %s %s",
+                event_id,
+                failed_to_fetch,
+            )
 
-            event_infos = []
+        remote_state = [
+            event_map[e_id] for e_id in state_event_ids if e_id in event_map
+        ]
 
-            for e in itertools.chain(auth_chain, state):
-                if e.event_id in seen_ids:
-                    continue
-                e.internal_metadata.outlier = True
-                auth_ids = e.auth_event_ids()
-                auth = {
-                    (e.type, e.state_key): e
-                    for e in auth_chain
-                    if e.event_id in auth_ids or e.type == EventTypes.Create
-                }
-                event_infos.append({"event": e, "auth_events": auth})
-                seen_ids.add(e.event_id)
+        if include_event_in_state:
+            remote_event = event_map.get(event_id)
+            if not remote_event:
+                raise Exception("Unable to get missing prev_event %s" % (event_id,))
+            if remote_event.is_state() and remote_event.rejected_reason is None:
+                remote_state.append(remote_event)
 
-            logger.info(
-                "[%s %s] persisting newly-received auth/state events %s",
+        auth_chain = [event_map[e_id] for e_id in auth_event_ids if e_id in event_map]
+        auth_chain.sort(key=lambda e: e.depth)
+
+        return remote_state, auth_chain
+
+    async def _get_events_from_store_or_dest(
+        self, destination: str, room_id: str, event_ids: Iterable[str]
+    ) -> Dict[str, EventBase]:
+        """Fetch events from a remote destination, checking if we already have them.
+
+        Persists any events we don't already have as outliers.
+
+        If we fail to fetch any of the events, a warning will be logged, and the event
+        will be omitted from the result. Likewise, any events which turn out not to
+        be in the given room.
+
+        Returns:
+            map from event_id to event
+        """
+        fetched_events = await self.store.get_events(event_ids, allow_rejected=True)
+
+        missing_events = set(event_ids) - fetched_events.keys()
+
+        if missing_events:
+            logger.debug(
+                "Fetching unknown state/auth events %s for room %s",
+                missing_events,
                 room_id,
-                event_id,
-                [e["event"].event_id for e in event_infos],
             )
-            yield self._handle_new_events(origin, event_infos)
+
+            await self._get_events_and_persist(
+                destination=destination, room_id=room_id, events=missing_events
+            )
+
+            # we need to make sure we re-load from the database to get the rejected
+            # state correct.
+            fetched_events.update(
+                (await self.store.get_events(missing_events, allow_rejected=True))
+            )
+
+        # check for events which were in the wrong room.
+        #
+        # this can happen if a remote server claims that the state or
+        # auth_events at an event in room A are actually events in room B
+
+        bad_events = [
+            (event_id, event.room_id)
+            for event_id, event in fetched_events.items()
+            if event.room_id != room_id
+        ]
+
+        for bad_event_id, bad_room_id in bad_events:
+            # This is a bogus situation, but since we may only discover it a long time
+            # after it happened, we try our best to carry on, by just omitting the
+            # bad events from the returned auth/state set.
+            logger.warning(
+                "Remote server %s claims event %s in room %s is an auth/state "
+                "event in room %s",
+                destination,
+                bad_event_id,
+                bad_room_id,
+                room_id,
+            )
+
+            del fetched_events[bad_event_id]
+
+        return fetched_events
+
+    async def _process_received_pdu(
+        self, origin: str, event: EventBase, state: Optional[Iterable[EventBase]],
+    ):
+        """ Called when we have a new pdu. We need to do auth checks and put it
+        through the StateHandler.
+
+        Args:
+            origin: server sending the event
+
+            event: event to be persisted
+
+            state: Normally None, but if we are handling a gap in the graph
+                (ie, we are missing one or more prev_events), the resolved state at the
+                event
+        """
+        room_id = event.room_id
+        event_id = event.event_id
+
+        logger.debug("[%s %s] Processing event: %s", room_id, event_id, event)
 
         try:
-            context = yield self._handle_new_event(origin, event, state=state)
+            context = await self._handle_new_event(origin, event, state=state)
         except AuthError as e:
             raise FederationError("ERROR", e.code, e.msg, affected=event.event_id)
 
-        room = yield self.store.get_room(room_id)
-
-        if not room:
-            try:
-                yield self.store.store_room(
-                    room_id=room_id, room_creator_user_id="", is_public=False
-                )
-            except StoreError:
-                logger.exception("Failed to store room.")
-
         if event.type == EventTypes.Member:
             if event.membership == Membership.JOIN:
                 # Only fire user_joined_room if the user has acutally
@@ -620,11 +698,11 @@ class FederationHandler(BaseHandler):
                 # changing their profile info.
                 newly_joined = True
 
-                prev_state_ids = yield context.get_prev_state_ids(self.store)
+                prev_state_ids = await context.get_prev_state_ids()
 
                 prev_state_id = prev_state_ids.get((event.type, event.state_key))
                 if prev_state_id:
-                    prev_state = yield self.store.get_event(
+                    prev_state = await self.store.get_event(
                         prev_state_id, allow_none=True
                     )
                     if prev_state and prev_state.membership == Membership.JOIN:
@@ -632,11 +710,82 @@ class FederationHandler(BaseHandler):
 
                 if newly_joined:
                     user = UserID.from_string(event.state_key)
-                    yield self.user_joined_room(user, room_id)
+                    await self.user_joined_room(user, room_id)
+
+        # For encrypted messages we check that we know about the sending device,
+        # if we don't then we mark the device cache for that user as stale.
+        if event.type == EventTypes.Encrypted:
+            device_id = event.content.get("device_id")
+            sender_key = event.content.get("sender_key")
+
+            cached_devices = await self.store.get_cached_devices_for_user(event.sender)
+
+            resync = False  # Whether we should resync device lists.
+
+            device = None
+            if device_id is not None:
+                device = cached_devices.get(device_id)
+                if device is None:
+                    logger.info(
+                        "Received event from remote device not in our cache: %s %s",
+                        event.sender,
+                        device_id,
+                    )
+                    resync = True
+
+            # We also check if the `sender_key` matches what we expect.
+            if sender_key is not None:
+                # Figure out what sender key we're expecting. If we know the
+                # device and recognize the algorithm then we can work out the
+                # exact key to expect. Otherwise check it matches any key we
+                # have for that device.
+                if device:
+                    keys = device.get("keys", {}).get("keys", {})
+
+                    if event.content.get("algorithm") == "m.megolm.v1.aes-sha2":
+                        # For this algorithm we expect a curve25519 key.
+                        key_name = "curve25519:%s" % (device_id,)
+                        current_keys = [keys.get(key_name)]
+                    else:
+                        # We don't know understand the algorithm, so we just
+                        # check it matches a key for the device.
+                        current_keys = keys.values()
+                elif device_id:
+                    # We don't have any keys for the device ID.
+                    current_keys = []
+                else:
+                    # The event didn't include a device ID, so we just look for
+                    # keys across all devices.
+                    current_keys = (
+                        key
+                        for device in cached_devices
+                        for key in device.get("keys", {}).get("keys", {}).values()
+                    )
+
+                # We now check that the sender key matches (one of) the expected
+                # keys.
+                if sender_key not in current_keys:
+                    logger.info(
+                        "Received event from remote device with unexpected sender key: %s %s: %s",
+                        event.sender,
+                        device_id or "<no device_id>",
+                        sender_key,
+                    )
+                    resync = True
+
+            if resync:
+                await self.store.mark_remote_user_device_cache_as_stale(event.sender)
+
+                # Immediately attempt a resync in the background
+                if self.config.worker_app:
+                    return run_in_background(self._user_device_resync, event.sender)
+                else:
+                    return run_in_background(
+                        self._device_list_updater.user_device_resync, event.sender
+                    )
 
     @log_function
-    @defer.inlineCallbacks
-    def backfill(self, dest, room_id, limit, extremities):
+    async def backfill(self, dest, room_id, limit, extremities):
         """ Trigger a backfill request to `dest` for the given `room_id`
 
         This will attempt to get more events from the remote. If the other side
@@ -653,9 +802,7 @@ class FederationHandler(BaseHandler):
         if dest == self.server_name:
             raise SynapseError(400, "Can't backfill from self.")
 
-        room_version = yield self.store.get_room_version(room_id)
-
-        events = yield self.federation_client.backfill(
+        events = await self.federation_client.backfill(
             dest, room_id, limit=limit, extremities=extremities
         )
 
@@ -670,8 +817,8 @@ class FederationHandler(BaseHandler):
         #     self._sanity_check_event(ev)
 
         # Don't bother processing events we already have.
-        seen_events = yield self.store.have_events_in_timeline(
-            set(e.event_id for e in events)
+        seen_events = await self.store.have_events_in_timeline(
+            {e.event_id for e in events}
         )
 
         events = [e for e in events if e.event_id not in seen_events]
@@ -681,8 +828,11 @@ class FederationHandler(BaseHandler):
 
         event_map = {e.event_id: e for e in events}
 
-        event_ids = set(e.event_id for e in events)
+        event_ids = {e.event_id for e in events}
 
+        # build a list of events whose prev_events weren't in the batch.
+        # (XXX: this will include events whose prev_events we already have; that doesn't
+        # sound right?)
         edges = [ev.event_id for ev in events if set(ev.prev_event_ids()) - event_ids]
 
         logger.info("backfill: Got %d events with %d edges", len(events), len(edges))
@@ -693,113 +843,32 @@ class FederationHandler(BaseHandler):
         state_events = {}
         events_to_state = {}
         for e_id in edges:
-            state, auth = yield self.federation_client.get_state_for_room(
-                destination=dest, room_id=room_id, event_id=e_id
+            state, auth = await self._get_state_for_room(
+                destination=dest,
+                room_id=room_id,
+                event_id=e_id,
+                include_event_in_state=False,
             )
             auth_events.update({a.event_id: a for a in auth})
             auth_events.update({s.event_id: s for s in state})
             state_events.update({s.event_id: s for s in state})
             events_to_state[e_id] = state
 
-        required_auth = set(
+        required_auth = {
             a_id
             for event in events
             + list(state_events.values())
             + list(auth_events.values())
             for a_id in event.auth_event_ids()
-        )
+        }
         auth_events.update(
             {e_id: event_map[e_id] for e_id in required_auth if e_id in event_map}
         )
-        missing_auth = required_auth - set(auth_events)
-        failed_to_fetch = set()
-
-        # Try and fetch any missing auth events from both DB and remote servers.
-        # We repeatedly do this until we stop finding new auth events.
-        while missing_auth - failed_to_fetch:
-            logger.info("Missing auth for backfill: %r", missing_auth)
-            ret_events = yield self.store.get_events(missing_auth - failed_to_fetch)
-            auth_events.update(ret_events)
-
-            required_auth.update(
-                a_id for event in ret_events.values() for a_id in event.auth_event_ids()
-            )
-            missing_auth = required_auth - set(auth_events)
-
-            if missing_auth - failed_to_fetch:
-                logger.info(
-                    "Fetching missing auth for backfill: %r",
-                    missing_auth - failed_to_fetch,
-                )
-
-                results = yield make_deferred_yieldable(
-                    defer.gatherResults(
-                        [
-                            run_in_background(
-                                self.federation_client.get_pdu,
-                                [dest],
-                                event_id,
-                                room_version=room_version,
-                                outlier=True,
-                                timeout=10000,
-                            )
-                            for event_id in missing_auth - failed_to_fetch
-                        ],
-                        consumeErrors=True,
-                    )
-                ).addErrback(unwrapFirstError)
-                auth_events.update({a.event_id: a for a in results if a})
-                required_auth.update(
-                    a_id
-                    for event in results
-                    if event
-                    for a_id in event.auth_event_ids()
-                )
-                missing_auth = required_auth - set(auth_events)
-
-                failed_to_fetch = missing_auth - set(auth_events)
-
-        seen_events = yield self.store.have_seen_events(
-            set(auth_events.keys()) | set(state_events.keys())
-        )
-
-        # We now have a chunk of events plus associated state and auth chain to
-        # persist. We do the persistence in two steps:
-        #   1. Auth events and state get persisted as outliers, plus the
-        #      backward extremities get persisted (as non-outliers).
-        #   2. The rest of the events in the chunk get persisted one by one, as
-        #      each one depends on the previous event for its state.
-        #
-        # The important thing is that events in the chunk get persisted as
-        # non-outliers, including when those events are also in the state or
-        # auth chain. Caution must therefore be taken to ensure that they are
-        # not accidentally marked as outliers.
 
-        # Step 1a: persist auth events that *don't* appear in the chunk
         ev_infos = []
-        for a in auth_events.values():
-            # We only want to persist auth events as outliers that we haven't
-            # seen and aren't about to persist as part of the backfilled chunk.
-            if a.event_id in seen_events or a.event_id in event_map:
-                continue
-
-            a.internal_metadata.outlier = True
-            ev_infos.append(
-                {
-                    "event": a,
-                    "auth_events": {
-                        (
-                            auth_events[a_id].type,
-                            auth_events[a_id].state_key,
-                        ): auth_events[a_id]
-                        for a_id in a.auth_event_ids()
-                        if a_id in auth_events
-                    },
-                }
-            )
 
-        # Step 1b: persist the events in the chunk we fetched state for (i.e.
-        # the backwards extremities) as non-outliers.
+        # Step 1: persist the events in the chunk we fetched state for (i.e.
+        # the backwards extremities), with custom auth events and state
         for e_id in events_to_state:
             # For paranoia we ensure that these events are marked as
             # non-outliers
@@ -807,10 +876,10 @@ class FederationHandler(BaseHandler):
             assert not ev.internal_metadata.is_outlier()
 
             ev_infos.append(
-                {
-                    "event": ev,
-                    "state": events_to_state[e_id],
-                    "auth_events": {
+                _NewEventInfo(
+                    event=ev,
+                    state=events_to_state[e_id],
+                    auth_events={
                         (
                             auth_events[a_id].type,
                             auth_events[a_id].state_key,
@@ -818,10 +887,10 @@ class FederationHandler(BaseHandler):
                         for a_id in ev.auth_event_ids()
                         if a_id in auth_events
                     },
-                }
+                )
             )
 
-        yield self._handle_new_events(dest, ev_infos, backfilled=True)
+        await self._handle_new_events(dest, ev_infos, backfilled=True)
 
         # Step 2: Persist the rest of the events in the chunk one by one
         events.sort(key=lambda e: e.depth)
@@ -837,16 +906,15 @@ class FederationHandler(BaseHandler):
             # We store these one at a time since each event depends on the
             # previous to work out the state.
             # TODO: We can probably do something more clever here.
-            yield self._handle_new_event(dest, event, backfilled=True)
+            await self._handle_new_event(dest, event, backfilled=True)
 
         return events
 
-    @defer.inlineCallbacks
-    def maybe_backfill(self, room_id, current_depth):
+    async def maybe_backfill(self, room_id, current_depth):
         """Checks the database to see if we should backfill before paginating,
         and if so do.
         """
-        extremities = yield self.store.get_oldest_events_with_depth_in_room(room_id)
+        extremities = await self.store.get_oldest_events_with_depth_in_room(room_id)
 
         if not extremities:
             logger.debug("Not backfilling as no extremeties found.")
@@ -878,16 +946,18 @@ class FederationHandler(BaseHandler):
         #   state *before* the event, ignoring the special casing certain event
         #   types have.
 
-        forward_events = yield self.store.get_successor_events(list(extremities))
+        forward_events = await self.store.get_successor_events(list(extremities))
 
-        extremities_events = yield self.store.get_events(
-            forward_events, check_redacted=False, get_prev_content=False
+        extremities_events = await self.store.get_events(
+            forward_events,
+            redact_behaviour=EventRedactBehaviour.AS_IS,
+            get_prev_content=False,
         )
 
         # We set `check_history_visibility_only` as we might otherwise get false
         # positives from users having been erased.
-        filtered_extremities = yield filter_events_for_server(
-            self.store,
+        filtered_extremities = await filter_events_for_server(
+            self.storage,
             self.server_name,
             list(extremities_events.values()),
             redact=False,
@@ -916,7 +986,7 @@ class FederationHandler(BaseHandler):
         # First we try hosts that are already in the room
         # TODO: HEURISTIC ALERT.
 
-        curr_state = yield self.state_handler.get_current_state(room_id)
+        curr_state = await self.state_handler.get_current_state(room_id)
 
         def get_domains_from_state(state):
             """Get joined domains from state
@@ -955,12 +1025,11 @@ class FederationHandler(BaseHandler):
             domain for domain, depth in curr_domains if domain != self.server_name
         ]
 
-        @defer.inlineCallbacks
-        def try_backfill(domains):
+        async def try_backfill(domains):
             # TODO: Should we try multiple of these at a time?
             for dom in domains:
                 try:
-                    yield self.backfill(
+                    await self.backfill(
                         dom, room_id, limit=100, extremities=extremities
                     )
                     # If this succeeded then we probably already have the
@@ -970,6 +1039,12 @@ class FederationHandler(BaseHandler):
                 except SynapseError as e:
                     logger.info("Failed to backfill from %s because %s", dom, e)
                     continue
+                except HttpResponseException as e:
+                    if 400 <= e.code < 500:
+                        raise e.to_synapse_error()
+
+                    logger.info("Failed to backfill from %s because %s", dom, e)
+                    continue
                 except CodeMessageException as e:
                     if 400 <= e.code < 500:
                         raise
@@ -991,7 +1066,7 @@ class FederationHandler(BaseHandler):
 
             return False
 
-        success = yield try_backfill(likely_domains)
+        success = await try_backfill(likely_domains)
         if success:
             return True
 
@@ -1005,7 +1080,7 @@ class FederationHandler(BaseHandler):
 
         logger.debug("calling resolve_state_groups in _maybe_backfill")
         resolve = preserve_fn(self.state_handler.resolve_state_groups_for_events)
-        states = yield make_deferred_yieldable(
+        states = await make_deferred_yieldable(
             defer.gatherResults(
                 [resolve(room_id, [e]) for e in event_ids], consumeErrors=True
             )
@@ -1015,7 +1090,7 @@ class FederationHandler(BaseHandler):
         # event_ids.
         states = dict(zip(event_ids, [s.state for s in states]))
 
-        state_map = yield self.store.get_events(
+        state_map = await self.store.get_events(
             [e_id for ids in itervalues(states) for e_id in itervalues(ids)],
             get_prev_content=False,
         )
@@ -1031,7 +1106,7 @@ class FederationHandler(BaseHandler):
         for e_id, _ in sorted_extremeties_tuple:
             likely_domains = get_domains_from_state(states[e_id])
 
-            success = yield try_backfill(
+            success = await try_backfill(
                 [dom for dom, _ in likely_domains if dom not in tried_domains]
             )
             if success:
@@ -1041,6 +1116,56 @@ class FederationHandler(BaseHandler):
 
         return False
 
+    async def _get_events_and_persist(
+        self, destination: str, room_id: str, events: Iterable[str]
+    ):
+        """Fetch the given events from a server, and persist them as outliers.
+
+        Logs a warning if we can't find the given event.
+        """
+
+        room_version = await self.store.get_room_version(room_id)
+
+        event_infos = []
+
+        async def get_event(event_id: str):
+            with nested_logging_context(event_id):
+                try:
+                    event = await self.federation_client.get_pdu(
+                        [destination], event_id, room_version, outlier=True,
+                    )
+                    if event is None:
+                        logger.warning(
+                            "Server %s didn't return event %s", destination, event_id,
+                        )
+                        return
+
+                    # recursively fetch the auth events for this event
+                    auth_events = await self._get_events_from_store_or_dest(
+                        destination, room_id, event.auth_event_ids()
+                    )
+                    auth = {}
+                    for auth_event_id in event.auth_event_ids():
+                        ae = auth_events.get(auth_event_id)
+                        if ae:
+                            auth[(ae.type, ae.state_key)] = ae
+
+                    event_infos.append(_NewEventInfo(event, None, auth))
+
+                except Exception as e:
+                    logger.warning(
+                        "Error fetching missing state/auth event %s: %s %s",
+                        event_id,
+                        type(e),
+                        e,
+                    )
+
+        await concurrently_execute(get_event, events, 5)
+
+        await self._handle_new_events(
+            destination, event_infos,
+        )
+
     def _sanity_check_event(self, ev):
         """
         Do some early sanity checks of a received event
@@ -1058,7 +1183,7 @@ class FederationHandler(BaseHandler):
             SynapseError if the event does not pass muster
         """
         if len(ev.prev_event_ids()) > 20:
-            logger.warn(
+            logger.warning(
                 "Rejecting event %s which has %i prev_events",
                 ev.event_id,
                 len(ev.prev_event_ids()),
@@ -1066,20 +1191,19 @@ class FederationHandler(BaseHandler):
             raise SynapseError(http_client.BAD_REQUEST, "Too many prev_events")
 
         if len(ev.auth_event_ids()) > 10:
-            logger.warn(
+            logger.warning(
                 "Rejecting event %s which has %i auth_events",
                 ev.event_id,
                 len(ev.auth_event_ids()),
             )
             raise SynapseError(http_client.BAD_REQUEST, "Too many auth_events")
 
-    @defer.inlineCallbacks
-    def send_invite(self, target_host, event):
+    async def send_invite(self, target_host, event):
         """ Sends the invite to the remote server for signing.
 
         Invites must be signed by the invitee's server before distribution.
         """
-        pdu = yield self.federation_client.send_invite(
+        pdu = await self.federation_client.send_invite(
             destination=target_host,
             room_id=event.room_id,
             event_id=event.event_id,
@@ -1088,19 +1212,18 @@ class FederationHandler(BaseHandler):
 
         return pdu
 
-    @defer.inlineCallbacks
-    def on_event_auth(self, event_id):
-        event = yield self.store.get_event(event_id)
-        auth = yield self.store.get_auth_chain(
-            [auth_id for auth_id in event.auth_event_ids()], include_given=True
+    async def on_event_auth(self, event_id: str) -> List[EventBase]:
+        event = await self.store.get_event(event_id)
+        auth = await self.store.get_auth_chain(
+            list(event.auth_event_ids()), include_given=True
         )
-        return [e for e in auth]
+        return list(auth)
 
-    @log_function
-    @defer.inlineCallbacks
-    def do_invite_join(self, target_hosts, room_id, joinee, content):
+    async def do_invite_join(
+        self, target_hosts: Iterable[str], room_id: str, joinee: str, content: JsonDict
+    ) -> Tuple[str, int]:
         """ Attempts to join the `joinee` to the room `room_id` via the
-        server `target_host`.
+        servers contained in `target_hosts`.
 
         This first triggers a /make_join/ request that returns a partial
         event that we can fill out and sign. This is then sent to the
@@ -1109,10 +1232,23 @@ class FederationHandler(BaseHandler):
 
         We suspend processing of any received events from this room until we
         have finished processing the join.
+
+        Args:
+            target_hosts: List of servers to attempt to join the room with.
+
+            room_id: The ID of the room to join.
+
+            joinee: The User ID of the joining user.
+
+            content: The event content to use for the join event.
         """
+        # TODO: We should be able to call this on workers, but the upgrading of
+        # room stuff after join currently doesn't work on workers.
+        assert self.config.worker.worker_app is None
+
         logger.debug("Joining %s to %s", joinee, room_id)
 
-        origin, event, event_format_version = yield self._make_and_verify_event(
+        origin, event, room_version_obj = await self._make_and_verify_event(
             target_hosts,
             room_id,
             joinee,
@@ -1128,7 +1264,7 @@ class FederationHandler(BaseHandler):
 
         self.room_queues[room_id] = []
 
-        yield self._clean_room_for_join(room_id)
+        await self._clean_room_for_join(room_id)
 
         handled_events = set()
 
@@ -1140,8 +1276,9 @@ class FederationHandler(BaseHandler):
                 target_hosts.insert(0, origin)
             except ValueError:
                 pass
-            ret = yield self.federation_client.send_join(
-                target_hosts, event, event_format_version
+
+            ret = await self.federation_client.send_join(
+                target_hosts, event, room_version_obj
             )
 
             origin = ret["origin"]
@@ -1158,17 +1295,49 @@ class FederationHandler(BaseHandler):
 
             logger.debug("do_invite_join event: %s", event)
 
-            try:
-                yield self.store.store_room(
-                    room_id=room_id, room_creator_user_id="", is_public=False
-                )
-            except Exception:
-                # FIXME
-                pass
+            # if this is the first time we've joined this room, it's time to add
+            # a row to `rooms` with the correct room version. If there's already a
+            # row there, we should override it, since it may have been populated
+            # based on an invite request which lied about the room version.
+            #
+            # federation_client.send_join has already checked that the room
+            # version in the received create event is the same as room_version_obj,
+            # so we can rely on it now.
+            #
+            await self.store.upsert_room_on_join(
+                room_id=room_id, room_version=room_version_obj,
+            )
 
-            yield self._persist_auth_tree(origin, auth_chain, state, event)
+            max_stream_id = await self._persist_auth_tree(
+                origin, auth_chain, state, event, room_version_obj
+            )
+
+            # We wait here until this instance has seen the events come down
+            # replication (if we're using replication) as the below uses caches.
+            #
+            # TODO: Currently the events stream is written to from master
+            await self._replication.wait_for_stream_position(
+                self.config.worker.writers.events, "events", max_stream_id
+            )
+
+            # Check whether this room is the result of an upgrade of a room we already know
+            # about. If so, migrate over user information
+            predecessor = await self.store.get_room_predecessor(room_id)
+            if not predecessor or not isinstance(predecessor.get("room_id"), str):
+                return event.event_id, max_stream_id
+            old_room_id = predecessor["room_id"]
+            logger.debug(
+                "Found predecessor for %s during remote join: %s", room_id, old_room_id
+            )
+
+            # We retrieve the room member handler here as to not cause a cyclic dependency
+            member_handler = self.hs.get_room_member_handler()
+            await member_handler.transfer_room_state_on_room_upgrade(
+                old_room_id, room_id
+            )
 
             logger.debug("Finished joining %s to %s", joinee, room_id)
+            return event.event_id, max_stream_id
         finally:
             room_queue = self.room_queues[room_id]
             del self.room_queues[room_id]
@@ -1181,10 +1350,7 @@ class FederationHandler(BaseHandler):
 
             run_in_background(self._handle_queued_pdus, room_queue)
 
-        return True
-
-    @defer.inlineCallbacks
-    def _handle_queued_pdus(self, room_queue):
+    async def _handle_queued_pdus(self, room_queue):
         """Process PDUs which got queued up while we were busy send_joining.
 
         Args:
@@ -1200,28 +1366,24 @@ class FederationHandler(BaseHandler):
                     p.room_id,
                 )
                 with nested_logging_context(p.event_id):
-                    yield self.on_receive_pdu(origin, p, sent_to_us_directly=True)
+                    await self.on_receive_pdu(origin, p, sent_to_us_directly=True)
             except Exception as e:
-                logger.warn(
+                logger.warning(
                     "Error handling queued PDU %s from %s: %s", p.event_id, origin, e
                 )
 
-    @defer.inlineCallbacks
-    @log_function
-    def on_make_join_request(self, origin, room_id, user_id):
+    async def on_make_join_request(
+        self, origin: str, room_id: str, user_id: str
+    ) -> EventBase:
         """ We've received a /make_join/ request, so we create a partial
         join event for the room and return that. We do *not* persist or
         process it until the other server has signed it and sent it back.
 
         Args:
-            origin (str): The (verified) server name of the requesting server.
-            room_id (str): Room to create join event in
-            user_id (str): The user to create the join for
-
-        Returns:
-            Deferred[FrozenEvent]
+            origin: The (verified) server name of the requesting server.
+            room_id: Room to create join event in
+            user_id: The user to create the join for
         """
-
         if get_domain_from_id(user_id) != origin:
             logger.info(
                 "Got /make_join request for user %r from different origin %s, ignoring",
@@ -1232,7 +1394,7 @@ class FederationHandler(BaseHandler):
 
         event_content = {"membership": Membership.JOIN}
 
-        room_version = yield self.store.get_room_version(room_id)
+        room_version = await self.store.get_room_version_id(room_id)
 
         builder = self.event_builder_factory.new(
             room_version,
@@ -1246,14 +1408,14 @@ class FederationHandler(BaseHandler):
         )
 
         try:
-            event, context = yield self.event_creation_handler.create_new_client_event(
+            event, context = await self.event_creation_handler.create_new_client_event(
                 builder=builder
             )
         except AuthError as e:
-            logger.warn("Failed to create join %r because %s", event, e)
+            logger.warning("Failed to create join to %s because %s", room_id, e)
             raise e
 
-        event_allowed = yield self.third_party_event_rules.check_event_allowed(
+        event_allowed = await self.third_party_event_rules.check_event_allowed(
             event, context
         )
         if not event_allowed:
@@ -1264,26 +1426,33 @@ class FederationHandler(BaseHandler):
 
         # The remote hasn't signed it yet, obviously. We'll do the full checks
         # when we get the event back in `on_send_join_request`
-        yield self.auth.check_from_context(
+        await self.auth.check_from_context(
             room_version, event, context, do_sig_check=False
         )
 
         return event
 
-    @defer.inlineCallbacks
-    @log_function
-    def on_send_join_request(self, origin, pdu):
+    async def on_send_join_request(self, origin, pdu):
         """ We have received a join event for a room. Fully process it and
         respond with the current state and auth chains.
         """
         event = pdu
 
         logger.debug(
-            "on_send_join_request: Got event: %s, signatures: %s",
+            "on_send_join_request from %s: Got event: %s, signatures: %s",
+            origin,
             event.event_id,
             event.signatures,
         )
 
+        if get_domain_from_id(event.sender) != origin:
+            logger.info(
+                "Got /send_join request for user %r from different origin %s",
+                event.sender,
+                origin,
+            )
+            raise SynapseError(403, "User not from origin", Codes.FORBIDDEN)
+
         event.internal_metadata.outlier = False
         # Send this event on behalf of the origin server.
         #
@@ -1300,9 +1469,9 @@ class FederationHandler(BaseHandler):
         # would introduce the danger of backwards-compatibility problems.
         event.internal_metadata.send_on_behalf_of = origin
 
-        context = yield self._handle_new_event(origin, event)
+        context = await self._handle_new_event(origin, event)
 
-        event_allowed = yield self.third_party_event_rules.check_event_allowed(
+        event_allowed = await self.third_party_event_rules.check_event_allowed(
             event, context
         )
         if not event_allowed:
@@ -1320,29 +1489,28 @@ class FederationHandler(BaseHandler):
         if event.type == EventTypes.Member:
             if event.content["membership"] == Membership.JOIN:
                 user = UserID.from_string(event.state_key)
-                yield self.user_joined_room(user, event.room_id)
+                await self.user_joined_room(user, event.room_id)
 
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = await context.get_prev_state_ids()
 
         state_ids = list(prev_state_ids.values())
-        auth_chain = yield self.store.get_auth_chain(state_ids)
+        auth_chain = await self.store.get_auth_chain(state_ids)
 
-        state = yield self.store.get_events(list(prev_state_ids.values()))
+        state = await self.store.get_events(list(prev_state_ids.values()))
 
         return {"state": list(state.values()), "auth_chain": auth_chain}
 
-    @defer.inlineCallbacks
-    def on_invite_request(self, origin, pdu):
+    async def on_invite_request(
+        self, origin: str, event: EventBase, room_version: RoomVersion
+    ):
         """ We've got an invite event. Process and persist it. Sign it.
 
         Respond with the now signed event.
         """
-        event = pdu
-
         if event.state_key is None:
             raise SynapseError(400, "The invite event did not have a state key")
 
-        is_blocked = yield self.store.is_room_blocked(event.room_id)
+        is_blocked = await self.store.is_room_blocked(event.room_id)
         if is_blocked:
             raise SynapseError(403, "This room has been blocked on this server")
 
@@ -1373,24 +1541,35 @@ class FederationHandler(BaseHandler):
         if event.state_key == self._server_notices_mxid:
             raise SynapseError(http_client.FORBIDDEN, "Cannot invite this user")
 
+        # keep a record of the room version, if we don't yet know it.
+        # (this may get overwritten if we later get a different room version in a
+        # join dance).
+        await self._maybe_store_room_on_invite(
+            room_id=event.room_id, room_version=room_version
+        )
+
         event.internal_metadata.outlier = True
         event.internal_metadata.out_of_band_membership = True
 
         event.signatures.update(
             compute_event_signature(
-                event.get_pdu_json(), self.hs.hostname, self.hs.config.signing_key[0]
+                room_version,
+                event.get_pdu_json(),
+                self.hs.hostname,
+                self.hs.config.signing_key[0],
             )
         )
 
-        context = yield self.state_handler.compute_event_context(event)
-        yield self.persist_events_and_notify([(event, context)])
+        context = await self.state_handler.compute_event_context(event)
+        await self.persist_events_and_notify([(event, context)])
 
         return event
 
-    @defer.inlineCallbacks
-    def do_remotely_reject_invite(self, target_hosts, room_id, user_id):
-        origin, event, event_format_version = yield self._make_and_verify_event(
-            target_hosts, room_id, user_id, "leave"
+    async def do_remotely_reject_invite(
+        self, target_hosts: Iterable[str], room_id: str, user_id: str, content: JsonDict
+    ) -> Tuple[EventBase, int]:
+        origin, event, room_version = await self._make_and_verify_event(
+            target_hosts, room_id, user_id, "leave", content=content
         )
         # Mark as outlier as we don't have any state for this event; we're not
         # even in the room.
@@ -1405,18 +1584,27 @@ class FederationHandler(BaseHandler):
         except ValueError:
             pass
 
-        yield self.federation_client.send_leave(target_hosts, event)
-
-        context = yield self.state_handler.compute_event_context(event)
-        yield self.persist_events_and_notify([(event, context)])
-
-        return event
-
-    @defer.inlineCallbacks
-    def _make_and_verify_event(
-        self, target_hosts, room_id, user_id, membership, content={}, params=None
-    ):
-        origin, event, format_ver = yield self.federation_client.make_membership_event(
+        await self.federation_client.send_leave(target_hosts, event)
+
+        context = await self.state_handler.compute_event_context(event)
+        stream_id = await self.persist_events_and_notify([(event, context)])
+
+        return event, stream_id
+
+    async def _make_and_verify_event(
+        self,
+        target_hosts: Iterable[str],
+        room_id: str,
+        user_id: str,
+        membership: str,
+        content: JsonDict = {},
+        params: Optional[Dict[str, str]] = None,
+    ) -> Tuple[str, EventBase, RoomVersion]:
+        (
+            origin,
+            event,
+            room_version,
+        ) = await self.federation_client.make_membership_event(
             target_hosts, room_id, user_id, membership, content, params=params
         )
 
@@ -1428,22 +1616,19 @@ class FederationHandler(BaseHandler):
         assert event.user_id == user_id
         assert event.state_key == user_id
         assert event.room_id == room_id
-        return origin, event, format_ver
+        return origin, event, room_version
 
-    @defer.inlineCallbacks
-    @log_function
-    def on_make_leave_request(self, origin, room_id, user_id):
+    async def on_make_leave_request(
+        self, origin: str, room_id: str, user_id: str
+    ) -> EventBase:
         """ We've received a /make_leave/ request, so we create a partial
         leave event for the room and return that. We do *not* persist or
         process it until the other server has signed it and sent it back.
 
         Args:
-            origin (str): The (verified) server name of the requesting server.
-            room_id (str): Room to create leave event in
-            user_id (str): The user to create the leave for
-
-        Returns:
-            Deferred[FrozenEvent]
+            origin: The (verified) server name of the requesting server.
+            room_id: Room to create leave event in
+            user_id: The user to create the leave for
         """
         if get_domain_from_id(user_id) != origin:
             logger.info(
@@ -1453,7 +1638,7 @@ class FederationHandler(BaseHandler):
             )
             raise SynapseError(403, "User not from origin", Codes.FORBIDDEN)
 
-        room_version = yield self.store.get_room_version(room_id)
+        room_version = await self.store.get_room_version_id(room_id)
         builder = self.event_builder_factory.new(
             room_version,
             {
@@ -1465,11 +1650,11 @@ class FederationHandler(BaseHandler):
             },
         )
 
-        event, context = yield self.event_creation_handler.create_new_client_event(
+        event, context = await self.event_creation_handler.create_new_client_event(
             builder=builder
         )
 
-        event_allowed = yield self.third_party_event_rules.check_event_allowed(
+        event_allowed = await self.third_party_event_rules.check_event_allowed(
             event, context
         )
         if not event_allowed:
@@ -1481,18 +1666,16 @@ class FederationHandler(BaseHandler):
         try:
             # The remote hasn't signed it yet, obviously. We'll do the full checks
             # when we get the event back in `on_send_leave_request`
-            yield self.auth.check_from_context(
+            await self.auth.check_from_context(
                 room_version, event, context, do_sig_check=False
             )
         except AuthError as e:
-            logger.warn("Failed to create new leave %r because %s", event, e)
+            logger.warning("Failed to create new leave %r because %s", event, e)
             raise e
 
         return event
 
-    @defer.inlineCallbacks
-    @log_function
-    def on_send_leave_request(self, origin, pdu):
+    async def on_send_leave_request(self, origin, pdu):
         """ We have received a leave event for a room. Fully process it."""
         event = pdu
 
@@ -1502,11 +1685,19 @@ class FederationHandler(BaseHandler):
             event.signatures,
         )
 
+        if get_domain_from_id(event.sender) != origin:
+            logger.info(
+                "Got /send_leave request for user %r from different origin %s",
+                event.sender,
+                origin,
+            )
+            raise SynapseError(403, "User not from origin", Codes.FORBIDDEN)
+
         event.internal_metadata.outlier = False
 
-        context = yield self._handle_new_event(origin, event)
+        context = await self._handle_new_event(origin, event)
 
-        event_allowed = yield self.third_party_event_rules.check_event_allowed(
+        event_allowed = await self.third_party_event_rules.check_event_allowed(
             event, context
         )
         if not event_allowed:
@@ -1523,16 +1714,15 @@ class FederationHandler(BaseHandler):
 
         return None
 
-    @defer.inlineCallbacks
-    def get_state_for_pdu(self, room_id, event_id):
+    async def get_state_for_pdu(self, room_id: str, event_id: str) -> List[EventBase]:
         """Returns the state at the event. i.e. not including said event.
         """
 
-        event = yield self.store.get_event(
+        event = await self.store.get_event(
             event_id, allow_none=False, check_room_id=room_id
         )
 
-        state_groups = yield self.store.get_state_groups(room_id, [event_id])
+        state_groups = await self.state_store.get_state_groups(room_id, [event_id])
 
         if state_groups:
             _, state = list(iteritems(state_groups)).pop()
@@ -1543,7 +1733,7 @@ class FederationHandler(BaseHandler):
                 if "replaces_state" in event.unsigned:
                     prev_id = event.unsigned["replaces_state"]
                     if prev_id != event.event_id:
-                        prev_event = yield self.store.get_event(prev_id)
+                        prev_event = await self.store.get_event(prev_id)
                         results[(event.type, event.state_key)] = prev_event
                 else:
                     del results[(event.type, event.state_key)]
@@ -1553,15 +1743,14 @@ class FederationHandler(BaseHandler):
         else:
             return []
 
-    @defer.inlineCallbacks
-    def get_state_ids_for_pdu(self, room_id, event_id):
+    async def get_state_ids_for_pdu(self, room_id: str, event_id: str) -> List[str]:
         """Returns the state at the event. i.e. not including said event.
         """
-        event = yield self.store.get_event(
+        event = await self.store.get_event(
             event_id, allow_none=False, check_room_id=room_id
         )
 
-        state_groups = yield self.store.get_state_groups_ids(room_id, [event_id])
+        state_groups = await self.state_store.get_state_groups_ids(room_id, [event_id])
 
         if state_groups:
             _, state = list(state_groups.items()).pop()
@@ -1580,46 +1769,50 @@ class FederationHandler(BaseHandler):
         else:
             return []
 
-    @defer.inlineCallbacks
     @log_function
-    def on_backfill_request(self, origin, room_id, pdu_list, limit):
-        in_room = yield self.auth.check_host_in_room(room_id, origin)
+    async def on_backfill_request(
+        self, origin: str, room_id: str, pdu_list: List[str], limit: int
+    ) -> List[EventBase]:
+        in_room = await self.auth.check_host_in_room(room_id, origin)
         if not in_room:
             raise AuthError(403, "Host not in room.")
 
-        events = yield self.store.get_backfill_events(room_id, pdu_list, limit)
+        # Synapse asks for 100 events per backfill request. Do not allow more.
+        limit = min(limit, 100)
 
-        events = yield filter_events_for_server(self.store, origin, events)
+        events = await self.store.get_backfill_events(room_id, pdu_list, limit)
+
+        events = await filter_events_for_server(self.storage, origin, events)
 
         return events
 
-    @defer.inlineCallbacks
     @log_function
-    def get_persisted_pdu(self, origin, event_id):
+    async def get_persisted_pdu(
+        self, origin: str, event_id: str
+    ) -> Optional[EventBase]:
         """Get an event from the database for the given server.
 
         Args:
-            origin [str]: hostname of server which is requesting the event; we
+            origin: hostname of server which is requesting the event; we
                will check that the server is allowed to see it.
-            event_id [str]: id of the event being requested
+            event_id: id of the event being requested
 
         Returns:
-            Deferred[EventBase|None]: None if we know nothing about the event;
-                otherwise the (possibly-redacted) event.
+            None if we know nothing about the event; otherwise the (possibly-redacted) event.
 
         Raises:
             AuthError if the server is not currently in the room
         """
-        event = yield self.store.get_event(
+        event = await self.store.get_event(
             event_id, allow_none=True, allow_rejected=True
         )
 
         if event:
-            in_room = yield self.auth.check_host_in_room(event.room_id, origin)
+            in_room = await self.auth.check_host_in_room(event.room_id, origin)
             if not in_room:
                 raise AuthError(403, "Host not in room.")
 
-            events = yield filter_events_for_server(self.store, origin, [event])
+            events = await filter_events_for_server(self.storage, origin, [event])
             event = events[0]
             return event
         else:
@@ -1628,11 +1821,10 @@ class FederationHandler(BaseHandler):
     def get_min_depth_for_context(self, context):
         return self.store.get_min_depth(context)
 
-    @defer.inlineCallbacks
-    def _handle_new_event(
+    async def _handle_new_event(
         self, origin, event, state=None, auth_events=None, backfilled=False
     ):
-        context = yield self._prep_event(
+        context = await self._prep_event(
             origin, event, state=state, auth_events=auth_events, backfilled=backfilled
         )
 
@@ -1640,12 +1832,16 @@ class FederationHandler(BaseHandler):
         # hack around with a try/finally instead.
         success = False
         try:
-            if not event.internal_metadata.is_outlier() and not backfilled:
-                yield self.action_generator.handle_push_actions_for_event(
+            if (
+                not event.internal_metadata.is_outlier()
+                and not backfilled
+                and not context.rejected
+            ):
+                await self.action_generator.handle_push_actions_for_event(
                     event, context
                 )
 
-            yield self.persist_events_and_notify(
+            await self.persist_events_and_notify(
                 [(event, context)], backfilled=backfilled
             )
             success = True
@@ -1657,8 +1853,12 @@ class FederationHandler(BaseHandler):
 
         return context
 
-    @defer.inlineCallbacks
-    def _handle_new_events(self, origin, event_infos, backfilled=False):
+    async def _handle_new_events(
+        self,
+        origin: str,
+        event_infos: Iterable[_NewEventInfo],
+        backfilled: bool = False,
+    ) -> None:
         """Creates the appropriate contexts and persists events. The events
         should not depend on one another, e.g. this should be used to persist
         a bunch of outliers, but not a chunk of individual events that depend
@@ -1667,36 +1867,41 @@ class FederationHandler(BaseHandler):
         Notifies about the events where appropriate.
         """
 
-        @defer.inlineCallbacks
-        def prep(ev_info):
-            event = ev_info["event"]
+        async def prep(ev_info: _NewEventInfo):
+            event = ev_info.event
             with nested_logging_context(suffix=event.event_id):
-                res = yield self._prep_event(
+                res = await self._prep_event(
                     origin,
                     event,
-                    state=ev_info.get("state"),
-                    auth_events=ev_info.get("auth_events"),
+                    state=ev_info.state,
+                    auth_events=ev_info.auth_events,
                     backfilled=backfilled,
                 )
             return res
 
-        contexts = yield make_deferred_yieldable(
+        contexts = await make_deferred_yieldable(
             defer.gatherResults(
                 [run_in_background(prep, ev_info) for ev_info in event_infos],
                 consumeErrors=True,
             )
         )
 
-        yield self.persist_events_and_notify(
+        await self.persist_events_and_notify(
             [
-                (ev_info["event"], context)
+                (ev_info.event, context)
                 for ev_info, context in zip(event_infos, contexts)
             ],
             backfilled=backfilled,
         )
 
-    @defer.inlineCallbacks
-    def _persist_auth_tree(self, origin, auth_events, state, event):
+    async def _persist_auth_tree(
+        self,
+        origin: str,
+        auth_events: List[EventBase],
+        state: List[EventBase],
+        event: EventBase,
+        room_version: RoomVersion,
+    ) -> int:
         """Checks the auth chain is valid (and passes auth checks) for the
         state and event. Then persists the auth chain and state atomically.
         Persists the event separately. Notifies about the persisted events
@@ -1705,18 +1910,17 @@ class FederationHandler(BaseHandler):
         Will attempt to fetch missing auth events.
 
         Args:
-            origin (str): Where the events came from
-            auth_events (list)
-            state (list)
-            event (Event)
-
-        Returns:
-            Deferred
+            origin: Where the events came from
+            auth_events
+            state
+            event
+            room_version: The room version we expect this room to have, and
+                will raise if it doesn't match the version in the create event.
         """
         events_to_context = {}
         for e in itertools.chain(auth_events, state):
             e.internal_metadata.outlier = True
-            ctx = yield self.state_handler.compute_event_context(e)
+            ctx = await self.state_handler.compute_event_context(e)
             events_to_context[e.event_id] = ctx
 
         event_map = {
@@ -1734,10 +1938,13 @@ class FederationHandler(BaseHandler):
             # invalid, and it would fail auth checks anyway.
             raise SynapseError(400, "No create event in state")
 
-        room_version = create_event.content.get(
+        room_version_id = create_event.content.get(
             "room_version", RoomVersions.V1.identifier
         )
 
+        if room_version.identifier != room_version_id:
+            raise SynapseError(400, "Room version mismatch")
+
         missing_auth_events = set()
         for e in itertools.chain(auth_events, state, [event]):
             for e_id in e.auth_event_ids():
@@ -1745,8 +1952,8 @@ class FederationHandler(BaseHandler):
                     missing_auth_events.add(e_id)
 
         for e_id in missing_auth_events:
-            m_ev = yield self.federation_client.get_pdu(
-                [origin], e_id, room_version=room_version, outlier=True, timeout=10000
+            m_ev = await self.federation_client.get_pdu(
+                [origin], e_id, room_version=room_version, outlier=True, timeout=10000,
             )
             if m_ev and m_ev.event_id == e_id:
                 event_map[e_id] = m_ev
@@ -1763,7 +1970,7 @@ class FederationHandler(BaseHandler):
                 auth_for_e[(EventTypes.Create, "")] = create_event
 
             try:
-                self.auth.check(room_version, e, auth_events=auth_for_e)
+                event_auth.check(room_version, e, auth_events=auth_for_e)
             except SynapseError as err:
                 # we may get SynapseErrors here as well as AuthErrors. For
                 # instance, there are a couple of (ancient) events in some
@@ -1771,94 +1978,80 @@ class FederationHandler(BaseHandler):
                 # cause SynapseErrors in auth.check. We don't want to give up
                 # the attempt to federate altogether in such cases.
 
-                logger.warn("Rejecting %s because %s", e.event_id, err.msg)
+                logger.warning("Rejecting %s because %s", e.event_id, err.msg)
 
                 if e == event:
                     raise
                 events_to_context[e.event_id].rejected = RejectedReason.AUTH_ERROR
 
-        yield self.persist_events_and_notify(
+        await self.persist_events_and_notify(
             [
                 (e, events_to_context[e.event_id])
                 for e in itertools.chain(auth_events, state)
             ]
         )
 
-        new_event_context = yield self.state_handler.compute_event_context(
+        new_event_context = await self.state_handler.compute_event_context(
             event, old_state=state
         )
 
-        yield self.persist_events_and_notify([(event, new_event_context)])
-
-    @defer.inlineCallbacks
-    def _prep_event(self, origin, event, state, auth_events, backfilled):
-        """
+        return await self.persist_events_and_notify([(event, new_event_context)])
 
-        Args:
-            origin:
-            event:
-            state:
-            auth_events:
-            backfilled (bool)
-
-        Returns:
-            Deferred, which resolves to synapse.events.snapshot.EventContext
-        """
-        context = yield self.state_handler.compute_event_context(event, old_state=state)
+    async def _prep_event(
+        self,
+        origin: str,
+        event: EventBase,
+        state: Optional[Iterable[EventBase]],
+        auth_events: Optional[StateMap[EventBase]],
+        backfilled: bool,
+    ) -> EventContext:
+        context = await self.state_handler.compute_event_context(event, old_state=state)
 
         if not auth_events:
-            prev_state_ids = yield context.get_prev_state_ids(self.store)
-            auth_events_ids = yield self.auth.compute_auth_events(
+            prev_state_ids = await context.get_prev_state_ids()
+            auth_events_ids = await self.auth.compute_auth_events(
                 event, prev_state_ids, for_verification=True
             )
-            auth_events = yield self.store.get_events(auth_events_ids)
+            auth_events = await self.store.get_events(auth_events_ids)
             auth_events = {(e.type, e.state_key): e for e in auth_events.values()}
 
         # This is a hack to fix some old rooms where the initial join event
         # didn't reference the create event in its auth events.
         if event.type == EventTypes.Member and not event.auth_event_ids():
             if len(event.prev_event_ids()) == 1 and event.depth < 5:
-                c = yield self.store.get_event(
+                c = await self.store.get_event(
                     event.prev_event_ids()[0], allow_none=True
                 )
                 if c and c.type == EventTypes.Create:
                     auth_events[(c.type, c.state_key)] = c
 
-        try:
-            yield self.do_auth(origin, event, context, auth_events=auth_events)
-        except AuthError as e:
-            logger.warn("[%s %s] Rejecting: %s", event.room_id, event.event_id, e.msg)
-
-            context.rejected = RejectedReason.AUTH_ERROR
+        context = await self.do_auth(origin, event, context, auth_events=auth_events)
 
         if not context.rejected:
-            yield self._check_for_soft_fail(event, state, backfilled)
+            await self._check_for_soft_fail(event, state, backfilled)
 
         if event.type == EventTypes.GuestAccess and not context.rejected:
-            yield self.maybe_kick_guest_users(event)
+            await self.maybe_kick_guest_users(event)
 
         return context
 
-    @defer.inlineCallbacks
-    def _check_for_soft_fail(self, event, state, backfilled):
-        """Checks if we should soft fail the event, if so marks the event as
+    async def _check_for_soft_fail(
+        self, event: EventBase, state: Optional[Iterable[EventBase]], backfilled: bool
+    ) -> None:
+        """Checks if we should soft fail the event; if so, marks the event as
         such.
 
         Args:
-            event (FrozenEvent)
-            state (dict|None): The state at the event if we don't have all the
-                event's prev events
-            backfilled (bool): Whether the event is from backfill
-
-        Returns:
-            Deferred
+            event
+            state: The state at the event if we don't have all the event's prev events
+            backfilled: Whether the event is from backfill
         """
         # For new (non-backfilled and non-outlier) events we check if the event
         # passes auth based on the current state. If it doesn't then we
         # "soft-fail" the event.
         do_soft_fail_check = not backfilled and not event.internal_metadata.is_outlier()
         if do_soft_fail_check:
-            extrem_ids = yield self.store.get_latest_event_ids_in_room(event.room_id)
+            extrem_ids = await self.store.get_latest_event_ids_in_room(event.room_id)
 
             extrem_ids = set(extrem_ids)
             prev_event_ids = set(event.prev_event_ids())
@@ -1869,7 +2062,8 @@ class FederationHandler(BaseHandler):
                 do_soft_fail_check = False
 
         if do_soft_fail_check:
-            room_version = yield self.store.get_room_version(event.room_id)
+            room_version = await self.store.get_room_version_id(event.room_id)
+            room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
 
             # Calculate the "current state".
             if state is not None:
@@ -1885,19 +2079,19 @@ class FederationHandler(BaseHandler):
                 # given state at the event. This should correctly handle cases
                 # like bans, especially with state res v2.
 
-                state_sets = yield self.store.get_state_groups(
+                state_sets = await self.state_store.get_state_groups(
                     event.room_id, extrem_ids
                 )
                 state_sets = list(state_sets.values())
                 state_sets.append(state)
-                current_state_ids = yield self.state_handler.resolve_events(
+                current_state_ids = await self.state_handler.resolve_events(
                     room_version, state_sets, event
                 )
                 current_state_ids = {
                     k: e.event_id for k, e in iteritems(current_state_ids)
                 }
             else:
-                current_state_ids = yield self.state_handler.get_current_state_ids(
+                current_state_ids = await self.state_handler.get_current_state_ids(
                     event.room_id, latest_event_ids=extrem_ids
                 )
 
@@ -1913,26 +2107,27 @@ class FederationHandler(BaseHandler):
                 e for k, e in iteritems(current_state_ids) if k in auth_types
             ]
 
-            current_auth_events = yield self.store.get_events(current_state_ids)
+            current_auth_events = await self.store.get_events(current_state_ids)
             current_auth_events = {
                 (e.type, e.state_key): e for e in current_auth_events.values()
             }
 
             try:
-                self.auth.check(room_version, event, auth_events=current_auth_events)
+                event_auth.check(
+                    room_version_obj, event, auth_events=current_auth_events
+                )
             except AuthError as e:
-                logger.warn("Soft-failing %r because %s", event, e)
+                logger.warning("Soft-failing %r because %s", event, e)
                 event.internal_metadata.soft_failed = True
 
-    @defer.inlineCallbacks
-    def on_query_auth(
+    async def on_query_auth(
         self, origin, event_id, room_id, remote_auth_chain, rejects, missing
     ):
-        in_room = yield self.auth.check_host_in_room(room_id, origin)
+        in_room = await self.auth.check_host_in_room(room_id, origin)
         if not in_room:
             raise AuthError(403, "Host not in room.")
 
-        event = yield self.store.get_event(
+        event = await self.store.get_event(
             event_id, allow_none=False, check_room_id=room_id
         )
 
@@ -1940,70 +2135,77 @@ class FederationHandler(BaseHandler):
         # don't want to fall into the trap of `missing` being wrong.
         for e in remote_auth_chain:
             try:
-                yield self._handle_new_event(origin, e)
+                await self._handle_new_event(origin, e)
             except AuthError:
                 pass
 
         # Now get the current auth_chain for the event.
-        local_auth_chain = yield self.store.get_auth_chain(
-            [auth_id for auth_id in event.auth_event_ids()], include_given=True
+        local_auth_chain = await self.store.get_auth_chain(
+            list(event.auth_event_ids()), include_given=True
         )
 
         # TODO: Check if we would now reject event_id. If so we need to tell
         # everyone.
 
-        ret = yield self.construct_auth_difference(local_auth_chain, remote_auth_chain)
+        ret = await self.construct_auth_difference(local_auth_chain, remote_auth_chain)
 
         logger.debug("on_query_auth returning: %s", ret)
 
         return ret
 
-    @defer.inlineCallbacks
-    def on_get_missing_events(
+    async def on_get_missing_events(
         self, origin, room_id, earliest_events, latest_events, limit
     ):
-        in_room = yield self.auth.check_host_in_room(room_id, origin)
+        in_room = await self.auth.check_host_in_room(room_id, origin)
         if not in_room:
             raise AuthError(403, "Host not in room.")
 
+        # Only allow up to 20 events to be retrieved per request.
         limit = min(limit, 20)
 
-        missing_events = yield self.store.get_missing_events(
+        missing_events = await self.store.get_missing_events(
             room_id=room_id,
             earliest_events=earliest_events,
             latest_events=latest_events,
             limit=limit,
         )
 
-        missing_events = yield filter_events_for_server(
-            self.store, origin, missing_events
+        missing_events = await filter_events_for_server(
+            self.storage, origin, missing_events
         )
 
         return missing_events
 
-    @defer.inlineCallbacks
-    @log_function
-    def do_auth(self, origin, event, context, auth_events):
+    async def do_auth(
+        self,
+        origin: str,
+        event: EventBase,
+        context: EventContext,
+        auth_events: StateMap[EventBase],
+    ) -> EventContext:
         """
 
         Args:
-            origin (str):
-            event (synapse.events.EventBase):
-            context (synapse.events.snapshot.EventContext):
-            auth_events (dict[(str, str)->synapse.events.EventBase]):
+            origin:
+            event:
+            context:
+            auth_events:
                 Map from (event_type, state_key) to event
 
-                What we expect the event's auth_events to be, based on the event's
-                position in the dag. I think? maybe??
+                Normally, our calculated auth_events based on the state of the room
+                at the event's position in the DAG, though occasionally (eg if the
+                event is an outlier), may be the auth events claimed by the remote
+                server.
 
                 Also NB that this function adds entries to it.
         Returns:
-            defer.Deferred[None]
+            updated context object
         """
-        room_version = yield self.store.get_room_version(event.room_id)
+        room_version = await self.store.get_room_version_id(event.room_id)
+        room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
 
         try:
-            yield self._update_auth_events_and_context_for_auth(
+            context = await self._update_auth_events_and_context_for_auth(
                 origin, event, context, auth_events
             )
         except Exception:
@@ -2018,15 +2220,20 @@ class FederationHandler(BaseHandler):
             )
 
         try:
-            self.auth.check(room_version, event, auth_events=auth_events)
+            event_auth.check(room_version_obj, event, auth_events=auth_events)
         except AuthError as e:
-            logger.warn("Failed auth resolution for %r because %s", event, e)
-            raise e
+            logger.warning("Failed auth resolution for %r because %s", event, e)
+            context.rejected = RejectedReason.AUTH_ERROR
 
-    @defer.inlineCallbacks
-    def _update_auth_events_and_context_for_auth(
-        self, origin, event, context, auth_events
-    ):
+        return context
+
+    async def _update_auth_events_and_context_for_auth(
+        self,
+        origin: str,
+        event: EventBase,
+        context: EventContext,
+        auth_events: StateMap[EventBase],
+    ) -> EventContext:
         """Helper for do_auth. See there for docs.
 
         Checks whether a given event has the expected auth events. If it
@@ -2034,59 +2241,59 @@ class FederationHandler(BaseHandler):
         we can come to a consensus (e.g. if one server missed some valid
         state).
 
-        This attempts to resovle any potential divergence of state between
+        This attempts to resolve any potential divergence of state between
         servers, but is not essential and so failures should not block further
         processing of the event.
 
         Args:
-            origin (str):
-            event (synapse.events.EventBase):
-            context (synapse.events.snapshot.EventContext):
-            auth_events (dict[(str, str)->synapse.events.EventBase]):
+            origin:
+            event:
+            context:
+
+            auth_events:
+                Map from (event_type, state_key) to event
+
+                Normally, our calculated auth_events based on the state of the room
+                at the event's position in the DAG, though occasionally (eg if the
+                event is an outlier), may be the auth events claimed by the remote
+                server.
+
+                Also NB that this function adds entries to it.
 
         Returns:
-            defer.Deferred[None]
+            updated context
         """
         event_auth_events = set(event.auth_event_ids())
 
-        if event.is_state():
-            event_key = (event.type, event.state_key)
-        else:
-            event_key = None
-
-        # if the event's auth_events refers to events which are not in our
-        # calculated auth_events, we need to fetch those events from somewhere.
-        #
-        # we start by fetching them from the store, and then try calling /event_auth/.
+        # missing_auth is the set of the event's auth_events which we don't yet have
+        # in auth_events.
         missing_auth = event_auth_events.difference(
             e.event_id for e in auth_events.values()
         )
 
+        # if we have missing events, we need to fetch those events from somewhere.
+        #
+        # we start by checking if they are in the store, and then try calling /event_auth/.
         if missing_auth:
-            # TODO: can we use store.have_seen_events here instead?
-            have_events = yield self.store.get_seen_events_with_rejections(missing_auth)
-            logger.debug("Got events %s from store", have_events)
-            missing_auth.difference_update(have_events.keys())
-        else:
-            have_events = {}
-
-        have_events.update({e.event_id: "" for e in auth_events.values()})
+            have_events = await self.store.have_seen_events(missing_auth)
+            logger.debug("Events %s are in the store", have_events)
+            missing_auth.difference_update(have_events)
 
         if missing_auth:
             # If we don't have all the auth events, we need to get them.
             logger.info("auth_events contains unknown events: %s", missing_auth)
             try:
                 try:
-                    remote_auth_chain = yield self.federation_client.get_event_auth(
+                    remote_auth_chain = await self.federation_client.get_event_auth(
                         origin, event.room_id, event.event_id
                     )
                 except RequestSendFailed as e:
                     # The other side isn't around or doesn't implement the
                     # endpoint, so lets just bail out.
                     logger.info("Failed to get event auth from remote: %s", e)
-                    return
+                    return context
 
-                seen_remotes = yield self.store.have_seen_events(
+                seen_remotes = await self.store.have_seen_events(
                     [e.event_id for e in remote_auth_chain]
                 )
 
@@ -2109,32 +2316,31 @@ class FederationHandler(BaseHandler):
                         logger.debug(
                             "do_auth %s missing_auth: %s", event.event_id, e.event_id
                         )
-                        yield self._handle_new_event(origin, e, auth_events=auth)
+                        await self._handle_new_event(origin, e, auth_events=auth)
 
                         if e.event_id in event_auth_events:
                             auth_events[(e.type, e.state_key)] = e
                     except AuthError:
                         pass
 
-                have_events = yield self.store.get_seen_events_with_rejections(
-                    event.auth_event_ids()
-                )
             except Exception:
-                # FIXME:
                 logger.exception("Failed to get auth chain")
 
         if event.internal_metadata.is_outlier():
+            # XXX: given that, for an outlier, we'll be working with the
+            # event's *claimed* auth events rather than those we calculated:
+            # (a) is there any point in this test, since different_auth below will
+            # obviously be empty
+            # (b) alternatively, why don't we do it earlier?
             logger.info("Skipping auth_event fetch for outlier")
-            return
+            return context
 
-        # FIXME: Assumes we have and stored all the state for all the
-        # prev_events
         different_auth = event_auth_events.difference(
             e.event_id for e in auth_events.values()
         )
 
         if not different_auth:
-            return
+            return context
 
         logger.info(
             "auth_events refers to events which are not in our calculated auth "
@@ -2142,175 +2348,94 @@ class FederationHandler(BaseHandler):
             different_auth,
         )
 
-        room_version = yield self.store.get_room_version(event.room_id)
+        # XXX: currently this checks for redactions but I'm not convinced that is
+        # necessary?
+        different_events = await self.store.get_events_as_list(different_auth)
 
-        different_events = yield make_deferred_yieldable(
-            defer.gatherResults(
-                [
-                    run_in_background(
-                        self.store.get_event, d, allow_none=True, allow_rejected=False
-                    )
-                    for d in different_auth
-                    if d in have_events and not have_events[d]
-                ],
-                consumeErrors=True,
-            )
-        ).addErrback(unwrapFirstError)
-
-        if different_events:
-            local_view = dict(auth_events)
-            remote_view = dict(auth_events)
-            remote_view.update(
-                {(d.type, d.state_key): d for d in different_events if d}
-            )
-
-            new_state = yield self.state_handler.resolve_events(
-                room_version,
-                [list(local_view.values()), list(remote_view.values())],
-                event,
-            )
-
-            logger.info(
-                "After state res: updating auth_events with new state %s",
-                {
-                    (d.type, d.state_key): d.event_id
-                    for d in new_state.values()
-                    if auth_events.get((d.type, d.state_key)) != d
-                },
-            )
-
-            auth_events.update(new_state)
-
-            different_auth = event_auth_events.difference(
-                e.event_id for e in auth_events.values()
-            )
-
-            yield self._update_context_for_auth_events(
-                event, context, auth_events, event_key
-            )
+        for d in different_events:
+            if d.room_id != event.room_id:
+                logger.warning(
+                    "Event %s refers to auth_event %s which is in a different room",
+                    event.event_id,
+                    d.event_id,
+                )
 
-        if not different_auth:
-            # we're done
-            return
+                # don't attempt to resolve the claimed auth events against our own
+                # in this case: just use our own auth events.
+                #
+                # XXX: should we reject the event in this case? It feels like we should,
+                # but then shouldn't we also do so if we've failed to fetch any of the
+                # auth events?
+                return context
+
+        # now we state-resolve between our own idea of the auth events, and the remote's
+        # idea of them.
+
+        local_state = auth_events.values()
+        remote_auth_events = dict(auth_events)
+        remote_auth_events.update({(d.type, d.state_key): d for d in different_events})
+        remote_state = remote_auth_events.values()
+
+        room_version = await self.store.get_room_version_id(event.room_id)
+        new_state = await self.state_handler.resolve_events(
+            room_version, (local_state, remote_state), event
+        )
 
         logger.info(
-            "auth_events still refers to events which are not in the calculated auth "
-            "chain after state resolution: %s",
-            different_auth,
+            "After state res: updating auth_events with new state %s",
+            {
+                (d.type, d.state_key): d.event_id
+                for d in new_state.values()
+                if auth_events.get((d.type, d.state_key)) != d
+            },
         )
 
-        # Only do auth resolution if we have something new to say.
-        # We can't prove an auth failure.
-        do_resolution = False
-
-        for e_id in different_auth:
-            if e_id in have_events:
-                if have_events[e_id] == RejectedReason.NOT_ANCESTOR:
-                    do_resolution = True
-                    break
-
-        if not do_resolution:
-            logger.info(
-                "Skipping auth resolution due to lack of provable rejection reasons"
-            )
-            return
-
-        logger.info("Doing auth resolution")
-
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
-
-        # 1. Get what we think is the auth chain.
-        auth_ids = yield self.auth.compute_auth_events(event, prev_state_ids)
-        local_auth_chain = yield self.store.get_auth_chain(auth_ids, include_given=True)
-
-        try:
-            # 2. Get remote difference.
-            try:
-                result = yield self.federation_client.query_auth(
-                    origin, event.room_id, event.event_id, local_auth_chain
-                )
-            except RequestSendFailed as e:
-                # The other side isn't around or doesn't implement the
-                # endpoint, so lets just bail out.
-                logger.info("Failed to query auth from remote: %s", e)
-                return
-
-            seen_remotes = yield self.store.have_seen_events(
-                [e.event_id for e in result["auth_chain"]]
-            )
-
-            # 3. Process any remote auth chain events we haven't seen.
-            for ev in result["auth_chain"]:
-                if ev.event_id in seen_remotes:
-                    continue
-
-                if ev.event_id == event.event_id:
-                    continue
-
-                try:
-                    auth_ids = ev.auth_event_ids()
-                    auth = {
-                        (e.type, e.state_key): e
-                        for e in result["auth_chain"]
-                        if e.event_id in auth_ids or event.type == EventTypes.Create
-                    }
-                    ev.internal_metadata.outlier = True
-
-                    logger.debug(
-                        "do_auth %s different_auth: %s", event.event_id, e.event_id
-                    )
-
-                    yield self._handle_new_event(origin, ev, auth_events=auth)
-
-                    if ev.event_id in event_auth_events:
-                        auth_events[(ev.type, ev.state_key)] = ev
-                except AuthError:
-                    pass
-
-        except Exception:
-            # FIXME:
-            logger.exception("Failed to query auth chain")
-
-        # 4. Look at rejects and their proofs.
-        # TODO.
+        auth_events.update(new_state)
 
-        yield self._update_context_for_auth_events(
-            event, context, auth_events, event_key
+        context = await self._update_context_for_auth_events(
+            event, context, auth_events
         )
 
-    @defer.inlineCallbacks
-    def _update_context_for_auth_events(self, event, context, auth_events, event_key):
+        return context
+
+    async def _update_context_for_auth_events(
+        self, event: EventBase, context: EventContext, auth_events: StateMap[EventBase]
+    ) -> EventContext:
         """Update the state_ids in an event context after auth event resolution,
         storing the changes as a new state group.
 
         Args:
-            event (Event): The event we're handling the context for
+            event: The event we're handling the context for
 
-            context (synapse.events.snapshot.EventContext): event context
-                to be updated
+            context: initial event context
 
-            auth_events (dict[(str, str)->str]): Events to update in the event
-                context.
+            auth_events: Events to update in the event context.
 
-            event_key ((str, str)): (type, state_key) for the current event.
-                this will not be included in the current_state in the context.
+        Returns:
+            new event context
         """
+        # exclude the state key of the new event from the current_state in the context.
+        if event.is_state():
+            event_key = (event.type, event.state_key)  # type: Optional[Tuple[str, str]]
+        else:
+            event_key = None
         state_updates = {
             k: a.event_id for k, a in iteritems(auth_events) if k != event_key
         }
-        current_state_ids = yield context.get_current_state_ids(self.store)
+
+        current_state_ids = await context.get_current_state_ids()
         current_state_ids = dict(current_state_ids)
 
         current_state_ids.update(state_updates)
 
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = await context.get_prev_state_ids()
         prev_state_ids = dict(prev_state_ids)
 
         prev_state_ids.update({k: a.event_id for k, a in iteritems(auth_events)})
 
         # create a new state group as a delta from the existing one.
         prev_group = context.state_group
-        state_group = yield self.store.store_state_group(
+        state_group = await self.state_store.store_state_group(
             event.event_id,
             event.room_id,
             prev_group=prev_group,
@@ -2318,16 +2443,18 @@ class FederationHandler(BaseHandler):
             current_state_ids=current_state_ids,
         )
 
-        yield context.update_state(
+        return EventContext.with_state(
             state_group=state_group,
+            state_group_before_event=context.state_group_before_event,
             current_state_ids=current_state_ids,
             prev_state_ids=prev_state_ids,
             prev_group=prev_group,
             delta_ids=state_updates,
         )
 
-    @defer.inlineCallbacks
-    def construct_auth_difference(self, local_auth, remote_auth):
+    async def construct_auth_difference(
+        self, local_auth: Iterable[EventBase], remote_auth: Iterable[EventBase]
+    ) -> Dict:
         """ Given a local and remote auth chain, find the differences. This
         assumes that we have already processed all events in remote_auth
 
@@ -2436,7 +2563,7 @@ class FederationHandler(BaseHandler):
         reason_map = {}
 
         for e in base_remote_rejected:
-            reason = yield self.store.get_rejection_reason(e.event_id)
+            reason = await self.store.get_rejection_reason(e.event_id)
             if reason is None:
                 # TODO: e is not in the current state, so we should
                 # construct some proof of that.
@@ -2444,15 +2571,6 @@ class FederationHandler(BaseHandler):
 
             reason_map[e.event_id] = reason
 
-            if reason == RejectedReason.AUTH_ERROR:
-                pass
-            elif reason == RejectedReason.REPLACED:
-                # TODO: Get proof
-                pass
-            elif reason == RejectedReason.NOT_ANCESTOR:
-                # TODO: Get proof.
-                pass
-
         logger.debug("construct_auth_difference returning")
 
         return {
@@ -2464,9 +2582,8 @@ class FederationHandler(BaseHandler):
             "missing": [e.event_id for e in missing_locals],
         }
 
-    @defer.inlineCallbacks
     @log_function
-    def exchange_third_party_invite(
+    async def exchange_third_party_invite(
         self, sender_user_id, target_user_id, room_id, signed
     ):
         third_party_invite = {"signed": signed}
@@ -2482,16 +2599,16 @@ class FederationHandler(BaseHandler):
             "state_key": target_user_id,
         }
 
-        if (yield self.auth.check_host_in_room(room_id, self.hs.hostname)):
-            room_version = yield self.store.get_room_version(room_id)
+        if await self.auth.check_host_in_room(room_id, self.hs.hostname):
+            room_version = await self.store.get_room_version_id(room_id)
             builder = self.event_builder_factory.new(room_version, event_dict)
 
             EventValidator().validate_builder(builder)
-            event, context = yield self.event_creation_handler.create_new_client_event(
+            event, context = await self.event_creation_handler.create_new_client_event(
                 builder=builder
             )
 
-            event_allowed = yield self.third_party_event_rules.check_event_allowed(
+            event_allowed = await self.third_party_event_rules.check_event_allowed(
                 event, context
             )
             if not event_allowed:
@@ -2503,58 +2620,58 @@ class FederationHandler(BaseHandler):
                     403, "This event is not allowed in this context", Codes.FORBIDDEN
                 )
 
-            event, context = yield self.add_display_name_to_third_party_invite(
+            event, context = await self.add_display_name_to_third_party_invite(
                 room_version, event_dict, event, context
             )
 
-            EventValidator().validate_new(event)
+            EventValidator().validate_new(event, self.config)
 
             # We need to tell the transaction queue to send this out, even
             # though the sender isn't a local user.
             event.internal_metadata.send_on_behalf_of = self.hs.hostname
 
             try:
-                yield self.auth.check_from_context(room_version, event, context)
+                await self.auth.check_from_context(room_version, event, context)
             except AuthError as e:
-                logger.warn("Denying new third party invite %r because %s", event, e)
+                logger.warning("Denying new third party invite %r because %s", event, e)
                 raise e
 
-            yield self._check_signature(event, context)
+            await self._check_signature(event, context)
+
+            # We retrieve the room member handler here as to not cause a cyclic dependency
             member_handler = self.hs.get_room_member_handler()
-            yield member_handler.send_membership_event(None, event, context)
+            await member_handler.send_membership_event(None, event, context)
         else:
-            destinations = set(x.split(":", 1)[-1] for x in (sender_user_id, room_id))
-            yield self.federation_client.forward_third_party_invite(
+            destinations = {x.split(":", 1)[-1] for x in (sender_user_id, room_id)}
+            await self.federation_client.forward_third_party_invite(
                 destinations, room_id, event_dict
             )
 
-    @defer.inlineCallbacks
-    @log_function
-    def on_exchange_third_party_invite_request(self, room_id, event_dict):
+    async def on_exchange_third_party_invite_request(
+        self, room_id: str, event_dict: JsonDict
+    ) -> None:
         """Handle an exchange_third_party_invite request from a remote server
 
         The remote server will call this when it wants to turn a 3pid invite
         into a normal m.room.member invite.
 
         Args:
-            room_id (str): The ID of the room.
+            room_id: The ID of the room.
 
             event_dict (dict[str, Any]): Dictionary containing the event body.
 
-        Returns:
-            Deferred: resolves (to None)
         """
-        room_version = yield self.store.get_room_version(room_id)
+        room_version = await self.store.get_room_version_id(room_id)
 
         # NB: event_dict has a particular specced format we might need to fudge
         # if we change event formats too much.
         builder = self.event_builder_factory.new(room_version, event_dict)
 
-        event, context = yield self.event_creation_handler.create_new_client_event(
+        event, context = await self.event_creation_handler.create_new_client_event(
             builder=builder
         )
 
-        event_allowed = yield self.third_party_event_rules.check_event_allowed(
+        event_allowed = await self.third_party_event_rules.check_event_allowed(
             event, context
         )
         if not event_allowed:
@@ -2565,26 +2682,26 @@ class FederationHandler(BaseHandler):
                 403, "This event is not allowed in this context", Codes.FORBIDDEN
             )
 
-        event, context = yield self.add_display_name_to_third_party_invite(
+        event, context = await self.add_display_name_to_third_party_invite(
             room_version, event_dict, event, context
         )
 
         try:
-            self.auth.check_from_context(room_version, event, context)
+            await self.auth.check_from_context(room_version, event, context)
         except AuthError as e:
-            logger.warn("Denying third party invite %r because %s", event, e)
+            logger.warning("Denying third party invite %r because %s", event, e)
             raise e
-        yield self._check_signature(event, context)
+        await self._check_signature(event, context)
 
         # We need to tell the transaction queue to send this out, even
         # though the sender isn't a local user.
         event.internal_metadata.send_on_behalf_of = get_domain_from_id(event.sender)
 
+        # We retrieve the room member handler here as to not cause a cyclic dependency
         member_handler = self.hs.get_room_member_handler()
-        yield member_handler.send_membership_event(None, event, context)
+        await member_handler.send_membership_event(None, event, context)
 
-    @defer.inlineCallbacks
-    def add_display_name_to_third_party_invite(
+    async def add_display_name_to_third_party_invite(
         self, room_version, event_dict, event, context
     ):
         key = (
@@ -2592,14 +2709,19 @@ class FederationHandler(BaseHandler):
             event.content["third_party_invite"]["signed"]["token"],
         )
         original_invite = None
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = await context.get_prev_state_ids()
         original_invite_id = prev_state_ids.get(key)
         if original_invite_id:
-            original_invite = yield self.store.get_event(
+            original_invite = await self.store.get_event(
                 original_invite_id, allow_none=True
             )
         if original_invite:
-            display_name = original_invite.content["display_name"]
+            # If the m.room.third_party_invite event's content is empty, it means the
+            # invite has been revoked. In this case, we don't have to raise an error here
+            # because the auth check will fail on the invite (because it's not able to
+            # fetch public keys from the m.room.third_party_invite event's content, which
+            # is empty).
+            display_name = original_invite.content.get("display_name")
             event_dict["content"]["third_party_invite"]["display_name"] = display_name
         else:
             logger.info(
@@ -2611,14 +2733,13 @@ class FederationHandler(BaseHandler):
 
         builder = self.event_builder_factory.new(room_version, event_dict)
         EventValidator().validate_builder(builder)
-        event, context = yield self.event_creation_handler.create_new_client_event(
+        event, context = await self.event_creation_handler.create_new_client_event(
             builder=builder
         )
-        EventValidator().validate_new(event)
+        EventValidator().validate_new(event, self.config)
         return (event, context)
 
-    @defer.inlineCallbacks
-    def _check_signature(self, event, context):
+    async def _check_signature(self, event, context):
         """
         Checks that the signature in the event is consistent with its invite.
 
@@ -2635,12 +2756,12 @@ class FederationHandler(BaseHandler):
         signed = event.content["third_party_invite"]["signed"]
         token = signed["token"]
 
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = await context.get_prev_state_ids()
         invite_event_id = prev_state_ids.get((EventTypes.ThirdPartyInvite, token))
 
         invite_event = None
         if invite_event_id:
-            invite_event = yield self.store.get_event(invite_event_id, allow_none=True)
+            invite_event = await self.store.get_event(invite_event_id, allow_none=True)
 
         if not invite_event:
             raise AuthError(403, "Could not find invite")
@@ -2689,7 +2810,7 @@ class FederationHandler(BaseHandler):
                             raise
                         try:
                             if "key_validity_url" in public_key_object:
-                                yield self._check_key_revocation(
+                                await self._check_key_revocation(
                                     public_key, public_key_object["key_validity_url"]
                                 )
                         except Exception:
@@ -2703,8 +2824,7 @@ class FederationHandler(BaseHandler):
                 last_exception = e
         raise last_exception
 
-    @defer.inlineCallbacks
-    def _check_key_revocation(self, public_key, url):
+    async def _check_key_revocation(self, public_key, url):
         """
         Checks whether public_key has been revoked.
 
@@ -2718,47 +2838,58 @@ class FederationHandler(BaseHandler):
                 for revocation.
         """
         try:
-            response = yield self.http_client.get_json(url, {"public_key": public_key})
+            response = await self.http_client.get_json(url, {"public_key": public_key})
         except Exception:
             raise SynapseError(502, "Third party certificate could not be checked")
         if "valid" not in response or not response["valid"]:
             raise AuthError(403, "Third party certificate was invalid")
 
-    @defer.inlineCallbacks
-    def persist_events_and_notify(self, event_and_contexts, backfilled=False):
+    async def persist_events_and_notify(
+        self,
+        event_and_contexts: Sequence[Tuple[EventBase, EventContext]],
+        backfilled: bool = False,
+    ) -> int:
         """Persists events and tells the notifier/pushers about them, if
         necessary.
 
         Args:
-            event_and_contexts(list[tuple[FrozenEvent, EventContext]])
-            backfilled (bool): Whether these events are a result of
+            event_and_contexts:
+            backfilled: Whether these events are a result of
                 backfilling or not
-
-        Returns:
-            Deferred
         """
-        if self.config.worker_app:
-            yield self._send_events_to_master(
+        if self.config.worker.writers.events != self._instance_name:
+            result = await self._send_events(
+                instance_name=self.config.worker.writers.events,
                 store=self.store,
                 event_and_contexts=event_and_contexts,
                 backfilled=backfilled,
             )
+            return result["max_stream_id"]
         else:
-            max_stream_id = yield self.store.persist_events(
+            max_stream_id = await self.storage.persistence.persist_events(
                 event_and_contexts, backfilled=backfilled
             )
 
+            if self._ephemeral_messages_enabled:
+                for (event, context) in event_and_contexts:
+                    # If there's an expiry timestamp on the event, schedule its expiry.
+                    self._message_handler.maybe_schedule_expiry(event)
+
             if not backfilled:  # Never notify for backfilled events
                 for event, _ in event_and_contexts:
-                    yield self._notify_persisted_event(event, max_stream_id)
+                    await self._notify_persisted_event(event, max_stream_id)
+
+            return max_stream_id
 
-    def _notify_persisted_event(self, event, max_stream_id):
+    async def _notify_persisted_event(
+        self, event: EventBase, max_stream_id: int
+    ) -> None:
         """Checks to see if notifier/pushers should be notified about the
         event or not.
 
         Args:
-            event (FrozenEvent)
-            max_stream_id (int): The max_stream_id returned by persist_events
+            event:
+            max_stream_id: The max_stream_id returned by persist_events
         """
 
         extra_users = []
@@ -2782,32 +2913,31 @@ class FederationHandler(BaseHandler):
             event, event_stream_id, max_stream_id, extra_users=extra_users
         )
 
-        return self.pusher_pool.on_new_notifications(event_stream_id, max_stream_id)
+        await self.pusher_pool.on_new_notifications(event_stream_id, max_stream_id)
 
-    def _clean_room_for_join(self, room_id):
+    async def _clean_room_for_join(self, room_id: str) -> None:
         """Called to clean up any data in DB for a given room, ready for the
         server to join the room.
 
         Args:
-            room_id (str)
+            room_id
         """
         if self.config.worker_app:
-            return self._clean_room_for_join_client(room_id)
+            await self._clean_room_for_join_client(room_id)
         else:
-            return self.store.clean_room_for_join(room_id)
+            await self.store.clean_room_for_join(room_id)
 
-    def user_joined_room(self, user, room_id):
+    async def user_joined_room(self, user: UserID, room_id: str) -> None:
         """Called when a new user has joined the room
         """
         if self.config.worker_app:
-            return self._notify_user_membership_change(
+            await self._notify_user_membership_change(
                 room_id=room_id, user_id=user.to_string(), change="joined"
             )
         else:
-            return user_joined_room(self.distributor, user, room_id)
+            user_joined_room(self.distributor, user, room_id)
 
-    @defer.inlineCallbacks
-    def get_room_complexity(self, remote_room_hosts, room_id):
+    async def get_room_complexity(self, remote_room_hosts, room_id):
         """
         Fetch the complexity of a remote room over federation.
 
@@ -2821,12 +2951,12 @@ class FederationHandler(BaseHandler):
         """
 
         for host in remote_room_hosts:
-            res = yield self.federation_client.get_room_complexity(host, room_id)
+            res = await self.federation_client.get_room_complexity(host, room_id)
 
             # We got a result, return it.
             if res:
-                defer.returnValue(res)
+                return res
 
         # We fell off the bottom, couldn't get the complexity from anyone. Oh
         # well.
-        defer.returnValue(None)
+        return None
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index 46eb9ee88b..ebe8d25bd8 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -18,8 +18,6 @@ import logging
 
 from six import iteritems
 
-from twisted.internet import defer
-
 from synapse.api.errors import HttpResponseException, RequestSendFailed, SynapseError
 from synapse.types import get_domain_from_id
 
@@ -63,7 +61,7 @@ def _create_rerouter(func_name):
     return f
 
 
-class GroupsLocalHandler(object):
+class GroupsLocalWorkerHandler(object):
     def __init__(self, hs):
         self.hs = hs
         self.store = hs.get_datastore()
@@ -81,55 +79,33 @@ class GroupsLocalHandler(object):
 
         self.profile_handler = hs.get_profile_handler()
 
-        # Ensure attestations get renewed
-        hs.get_groups_attestation_renewer()
-
     # The following functions merely route the query to the local groups server
     # or federation depending on if the group is local or remote
 
     get_group_profile = _create_rerouter("get_group_profile")
-    update_group_profile = _create_rerouter("update_group_profile")
     get_rooms_in_group = _create_rerouter("get_rooms_in_group")
-
     get_invited_users_in_group = _create_rerouter("get_invited_users_in_group")
-
-    add_room_to_group = _create_rerouter("add_room_to_group")
-    update_room_in_group = _create_rerouter("update_room_in_group")
-    remove_room_from_group = _create_rerouter("remove_room_from_group")
-
-    update_group_summary_room = _create_rerouter("update_group_summary_room")
-    delete_group_summary_room = _create_rerouter("delete_group_summary_room")
-
-    update_group_category = _create_rerouter("update_group_category")
-    delete_group_category = _create_rerouter("delete_group_category")
     get_group_category = _create_rerouter("get_group_category")
     get_group_categories = _create_rerouter("get_group_categories")
-
-    update_group_summary_user = _create_rerouter("update_group_summary_user")
-    delete_group_summary_user = _create_rerouter("delete_group_summary_user")
-
-    update_group_role = _create_rerouter("update_group_role")
-    delete_group_role = _create_rerouter("delete_group_role")
     get_group_role = _create_rerouter("get_group_role")
     get_group_roles = _create_rerouter("get_group_roles")
 
-    set_group_join_policy = _create_rerouter("set_group_join_policy")
-
-    @defer.inlineCallbacks
-    def get_group_summary(self, group_id, requester_user_id):
+    async def get_group_summary(self, group_id, requester_user_id):
         """Get the group summary for a group.
 
         If the group is remote we check that the users have valid attestations.
         """
         if self.is_mine_id(group_id):
-            res = yield self.groups_server_handler.get_group_summary(
+            res = await self.groups_server_handler.get_group_summary(
                 group_id, requester_user_id
             )
         else:
             try:
-                res = yield self.transport_client.get_group_summary(
+                res = await self.transport_client.get_group_summary(
                     get_domain_from_id(group_id), group_id, requester_user_id
                 )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
             except RequestSendFailed:
                 raise SynapseError(502, "Failed to contact group server")
 
@@ -143,7 +119,7 @@ class GroupsLocalHandler(object):
                 attestation = entry.pop("attestation", {})
                 try:
                     if get_domain_from_id(g_user_id) != group_server_name:
-                        yield self.attestations.verify_attestation(
+                        await self.attestations.verify_attestation(
                             attestation,
                             group_id=group_id,
                             user_id=g_user_id,
@@ -160,22 +136,155 @@ class GroupsLocalHandler(object):
 
         # Add `is_publicised` flag to indicate whether the user has publicised their
         # membership of the group on their profile
-        result = yield self.store.get_publicised_groups_for_user(requester_user_id)
+        result = await self.store.get_publicised_groups_for_user(requester_user_id)
         is_publicised = group_id in result
 
         res.setdefault("user", {})["is_publicised"] = is_publicised
 
         return res
 
-    @defer.inlineCallbacks
-    def create_group(self, group_id, user_id, content):
+    async def get_users_in_group(self, group_id, requester_user_id):
+        """Get users in a group
+        """
+        if self.is_mine_id(group_id):
+            res = await self.groups_server_handler.get_users_in_group(
+                group_id, requester_user_id
+            )
+            return res
+
+        group_server_name = get_domain_from_id(group_id)
+
+        try:
+            res = await self.transport_client.get_users_in_group(
+                get_domain_from_id(group_id), group_id, requester_user_id
+            )
+        except HttpResponseException as e:
+            raise e.to_synapse_error()
+        except RequestSendFailed:
+            raise SynapseError(502, "Failed to contact group server")
+
+        chunk = res["chunk"]
+        valid_entries = []
+        for entry in chunk:
+            g_user_id = entry["user_id"]
+            attestation = entry.pop("attestation", {})
+            try:
+                if get_domain_from_id(g_user_id) != group_server_name:
+                    await self.attestations.verify_attestation(
+                        attestation,
+                        group_id=group_id,
+                        user_id=g_user_id,
+                        server_name=get_domain_from_id(g_user_id),
+                    )
+                valid_entries.append(entry)
+            except Exception as e:
+                logger.info("Failed to verify user is in group: %s", e)
+
+        res["chunk"] = valid_entries
+
+        return res
+
+    async def get_joined_groups(self, user_id):
+        group_ids = await self.store.get_joined_groups(user_id)
+        return {"groups": group_ids}
+
+    async def get_publicised_groups_for_user(self, user_id):
+        if self.hs.is_mine_id(user_id):
+            result = await self.store.get_publicised_groups_for_user(user_id)
+
+            # Check AS associated groups for this user - this depends on the
+            # RegExps in the AS registration file (under `users`)
+            for app_service in self.store.get_app_services():
+                result.extend(app_service.get_groups_for_user(user_id))
+
+            return {"groups": result}
+        else:
+            try:
+                bulk_result = await self.transport_client.bulk_get_publicised_groups(
+                    get_domain_from_id(user_id), [user_id]
+                )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
+            except RequestSendFailed:
+                raise SynapseError(502, "Failed to contact group server")
+
+            result = bulk_result.get("users", {}).get(user_id)
+            # TODO: Verify attestations
+            return {"groups": result}
+
+    async def bulk_get_publicised_groups(self, user_ids, proxy=True):
+        destinations = {}
+        local_users = set()
+
+        for user_id in user_ids:
+            if self.hs.is_mine_id(user_id):
+                local_users.add(user_id)
+            else:
+                destinations.setdefault(get_domain_from_id(user_id), set()).add(user_id)
+
+        if not proxy and destinations:
+            raise SynapseError(400, "Some user_ids are not local")
+
+        results = {}
+        failed_results = []
+        for destination, dest_user_ids in iteritems(destinations):
+            try:
+                r = await self.transport_client.bulk_get_publicised_groups(
+                    destination, list(dest_user_ids)
+                )
+                results.update(r["users"])
+            except Exception:
+                failed_results.extend(dest_user_ids)
+
+        for uid in local_users:
+            results[uid] = await self.store.get_publicised_groups_for_user(uid)
+
+            # Check AS associated groups for this user - this depends on the
+            # RegExps in the AS registration file (under `users`)
+            for app_service in self.store.get_app_services():
+                results[uid].extend(app_service.get_groups_for_user(uid))
+
+        return {"users": results}
+
+
+class GroupsLocalHandler(GroupsLocalWorkerHandler):
+    def __init__(self, hs):
+        super(GroupsLocalHandler, self).__init__(hs)
+
+        # Ensure attestations get renewed
+        hs.get_groups_attestation_renewer()
+
+    # The following functions merely route the query to the local groups server
+    # or federation depending on if the group is local or remote
+
+    update_group_profile = _create_rerouter("update_group_profile")
+
+    add_room_to_group = _create_rerouter("add_room_to_group")
+    update_room_in_group = _create_rerouter("update_room_in_group")
+    remove_room_from_group = _create_rerouter("remove_room_from_group")
+
+    update_group_summary_room = _create_rerouter("update_group_summary_room")
+    delete_group_summary_room = _create_rerouter("delete_group_summary_room")
+
+    update_group_category = _create_rerouter("update_group_category")
+    delete_group_category = _create_rerouter("delete_group_category")
+
+    update_group_summary_user = _create_rerouter("update_group_summary_user")
+    delete_group_summary_user = _create_rerouter("delete_group_summary_user")
+
+    update_group_role = _create_rerouter("update_group_role")
+    delete_group_role = _create_rerouter("delete_group_role")
+
+    set_group_join_policy = _create_rerouter("set_group_join_policy")
+
+    async def create_group(self, group_id, user_id, content):
         """Create a group
         """
 
         logger.info("Asking to create group with ID: %r", group_id)
 
         if self.is_mine_id(group_id):
-            res = yield self.groups_server_handler.create_group(
+            res = await self.groups_server_handler.create_group(
                 group_id, user_id, content
             )
             local_attestation = None
@@ -184,17 +293,19 @@ class GroupsLocalHandler(object):
             local_attestation = self.attestations.create_attestation(group_id, user_id)
             content["attestation"] = local_attestation
 
-            content["user_profile"] = yield self.profile_handler.get_profile(user_id)
+            content["user_profile"] = await self.profile_handler.get_profile(user_id)
 
             try:
-                res = yield self.transport_client.create_group(
+                res = await self.transport_client.create_group(
                     get_domain_from_id(group_id), group_id, user_id, content
                 )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
             except RequestSendFailed:
                 raise SynapseError(502, "Failed to contact group server")
 
             remote_attestation = res["attestation"]
-            yield self.attestations.verify_attestation(
+            await self.attestations.verify_attestation(
                 remote_attestation,
                 group_id=group_id,
                 user_id=user_id,
@@ -202,7 +313,7 @@ class GroupsLocalHandler(object):
             )
 
         is_publicised = content.get("publicise", False)
-        token = yield self.store.register_user_group_membership(
+        token = await self.store.register_user_group_membership(
             group_id,
             user_id,
             membership="join",
@@ -215,52 +326,11 @@ class GroupsLocalHandler(object):
 
         return res
 
-    @defer.inlineCallbacks
-    def get_users_in_group(self, group_id, requester_user_id):
-        """Get users in a group
-        """
-        if self.is_mine_id(group_id):
-            res = yield self.groups_server_handler.get_users_in_group(
-                group_id, requester_user_id
-            )
-            return res
-
-        group_server_name = get_domain_from_id(group_id)
-
-        try:
-            res = yield self.transport_client.get_users_in_group(
-                get_domain_from_id(group_id), group_id, requester_user_id
-            )
-        except RequestSendFailed:
-            raise SynapseError(502, "Failed to contact group server")
-
-        chunk = res["chunk"]
-        valid_entries = []
-        for entry in chunk:
-            g_user_id = entry["user_id"]
-            attestation = entry.pop("attestation", {})
-            try:
-                if get_domain_from_id(g_user_id) != group_server_name:
-                    yield self.attestations.verify_attestation(
-                        attestation,
-                        group_id=group_id,
-                        user_id=g_user_id,
-                        server_name=get_domain_from_id(g_user_id),
-                    )
-                valid_entries.append(entry)
-            except Exception as e:
-                logger.info("Failed to verify user is in group: %s", e)
-
-        res["chunk"] = valid_entries
-
-        return res
-
-    @defer.inlineCallbacks
-    def join_group(self, group_id, user_id, content):
+    async def join_group(self, group_id, user_id, content):
         """Request to join a group
         """
         if self.is_mine_id(group_id):
-            yield self.groups_server_handler.join_group(group_id, user_id, content)
+            await self.groups_server_handler.join_group(group_id, user_id, content)
             local_attestation = None
             remote_attestation = None
         else:
@@ -268,15 +338,17 @@ class GroupsLocalHandler(object):
             content["attestation"] = local_attestation
 
             try:
-                res = yield self.transport_client.join_group(
+                res = await self.transport_client.join_group(
                     get_domain_from_id(group_id), group_id, user_id, content
                 )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
             except RequestSendFailed:
                 raise SynapseError(502, "Failed to contact group server")
 
             remote_attestation = res["attestation"]
 
-            yield self.attestations.verify_attestation(
+            await self.attestations.verify_attestation(
                 remote_attestation,
                 group_id=group_id,
                 user_id=user_id,
@@ -286,7 +358,7 @@ class GroupsLocalHandler(object):
         # TODO: Check that the group is public and we're being added publically
         is_publicised = content.get("publicise", False)
 
-        token = yield self.store.register_user_group_membership(
+        token = await self.store.register_user_group_membership(
             group_id,
             user_id,
             membership="join",
@@ -299,12 +371,11 @@ class GroupsLocalHandler(object):
 
         return {}
 
-    @defer.inlineCallbacks
-    def accept_invite(self, group_id, user_id, content):
+    async def accept_invite(self, group_id, user_id, content):
         """Accept an invite to a group
         """
         if self.is_mine_id(group_id):
-            yield self.groups_server_handler.accept_invite(group_id, user_id, content)
+            await self.groups_server_handler.accept_invite(group_id, user_id, content)
             local_attestation = None
             remote_attestation = None
         else:
@@ -312,15 +383,17 @@ class GroupsLocalHandler(object):
             content["attestation"] = local_attestation
 
             try:
-                res = yield self.transport_client.accept_group_invite(
+                res = await self.transport_client.accept_group_invite(
                     get_domain_from_id(group_id), group_id, user_id, content
                 )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
             except RequestSendFailed:
                 raise SynapseError(502, "Failed to contact group server")
 
             remote_attestation = res["attestation"]
 
-            yield self.attestations.verify_attestation(
+            await self.attestations.verify_attestation(
                 remote_attestation,
                 group_id=group_id,
                 user_id=user_id,
@@ -330,7 +403,7 @@ class GroupsLocalHandler(object):
         # TODO: Check that the group is public and we're being added publically
         is_publicised = content.get("publicise", False)
 
-        token = yield self.store.register_user_group_membership(
+        token = await self.store.register_user_group_membership(
             group_id,
             user_id,
             membership="join",
@@ -343,31 +416,31 @@ class GroupsLocalHandler(object):
 
         return {}
 
-    @defer.inlineCallbacks
-    def invite(self, group_id, user_id, requester_user_id, config):
+    async def invite(self, group_id, user_id, requester_user_id, config):
         """Invite a user to a group
         """
         content = {"requester_user_id": requester_user_id, "config": config}
         if self.is_mine_id(group_id):
-            res = yield self.groups_server_handler.invite_to_group(
+            res = await self.groups_server_handler.invite_to_group(
                 group_id, user_id, requester_user_id, content
             )
         else:
             try:
-                res = yield self.transport_client.invite_to_group(
+                res = await self.transport_client.invite_to_group(
                     get_domain_from_id(group_id),
                     group_id,
                     user_id,
                     requester_user_id,
                     content,
                 )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
             except RequestSendFailed:
                 raise SynapseError(502, "Failed to contact group server")
 
         return res
 
-    @defer.inlineCallbacks
-    def on_invite(self, group_id, user_id, content):
+    async def on_invite(self, group_id, user_id, content):
         """One of our users were invited to a group
         """
         # TODO: Support auto join and rejection
@@ -382,7 +455,7 @@ class GroupsLocalHandler(object):
             if "avatar_url" in content["profile"]:
                 local_profile["avatar_url"] = content["profile"]["avatar_url"]
 
-        token = yield self.store.register_user_group_membership(
+        token = await self.store.register_user_group_membership(
             group_id,
             user_id,
             membership="invite",
@@ -390,19 +463,20 @@ class GroupsLocalHandler(object):
         )
         self.notifier.on_new_event("groups_key", token, users=[user_id])
         try:
-            user_profile = yield self.profile_handler.get_profile(user_id)
+            user_profile = await self.profile_handler.get_profile(user_id)
         except Exception as e:
-            logger.warn("No profile for user %s: %s", user_id, e)
+            logger.warning("No profile for user %s: %s", user_id, e)
             user_profile = {}
 
         return {"state": "invite", "user_profile": user_profile}
 
-    @defer.inlineCallbacks
-    def remove_user_from_group(self, group_id, user_id, requester_user_id, content):
+    async def remove_user_from_group(
+        self, group_id, user_id, requester_user_id, content
+    ):
         """Remove a user from a group
         """
         if user_id == requester_user_id:
-            token = yield self.store.register_user_group_membership(
+            token = await self.store.register_user_group_membership(
                 group_id, user_id, membership="leave"
             )
             self.notifier.on_new_event("groups_key", token, users=[user_id])
@@ -411,93 +485,31 @@ class GroupsLocalHandler(object):
             # retry if the group server is currently down.
 
         if self.is_mine_id(group_id):
-            res = yield self.groups_server_handler.remove_user_from_group(
+            res = await self.groups_server_handler.remove_user_from_group(
                 group_id, user_id, requester_user_id, content
             )
         else:
             content["requester_user_id"] = requester_user_id
             try:
-                res = yield self.transport_client.remove_user_from_group(
+                res = await self.transport_client.remove_user_from_group(
                     get_domain_from_id(group_id),
                     group_id,
                     requester_user_id,
                     user_id,
                     content,
                 )
+            except HttpResponseException as e:
+                raise e.to_synapse_error()
             except RequestSendFailed:
                 raise SynapseError(502, "Failed to contact group server")
 
         return res
 
-    @defer.inlineCallbacks
-    def user_removed_from_group(self, group_id, user_id, content):
+    async def user_removed_from_group(self, group_id, user_id, content):
         """One of our users was removed/kicked from a group
         """
         # TODO: Check if user in group
-        token = yield self.store.register_user_group_membership(
+        token = await self.store.register_user_group_membership(
             group_id, user_id, membership="leave"
         )
         self.notifier.on_new_event("groups_key", token, users=[user_id])
-
-    @defer.inlineCallbacks
-    def get_joined_groups(self, user_id):
-        group_ids = yield self.store.get_joined_groups(user_id)
-        return {"groups": group_ids}
-
-    @defer.inlineCallbacks
-    def get_publicised_groups_for_user(self, user_id):
-        if self.hs.is_mine_id(user_id):
-            result = yield self.store.get_publicised_groups_for_user(user_id)
-
-            # Check AS associated groups for this user - this depends on the
-            # RegExps in the AS registration file (under `users`)
-            for app_service in self.store.get_app_services():
-                result.extend(app_service.get_groups_for_user(user_id))
-
-            return {"groups": result}
-        else:
-            try:
-                bulk_result = yield self.transport_client.bulk_get_publicised_groups(
-                    get_domain_from_id(user_id), [user_id]
-                )
-            except RequestSendFailed:
-                raise SynapseError(502, "Failed to contact group server")
-
-            result = bulk_result.get("users", {}).get(user_id)
-            # TODO: Verify attestations
-            return {"groups": result}
-
-    @defer.inlineCallbacks
-    def bulk_get_publicised_groups(self, user_ids, proxy=True):
-        destinations = {}
-        local_users = set()
-
-        for user_id in user_ids:
-            if self.hs.is_mine_id(user_id):
-                local_users.add(user_id)
-            else:
-                destinations.setdefault(get_domain_from_id(user_id), set()).add(user_id)
-
-        if not proxy and destinations:
-            raise SynapseError(400, "Some user_ids are not local")
-
-        results = {}
-        failed_results = []
-        for destination, dest_user_ids in iteritems(destinations):
-            try:
-                r = yield self.transport_client.bulk_get_publicised_groups(
-                    destination, list(dest_user_ids)
-                )
-                results.update(r["users"])
-            except Exception:
-                failed_results.extend(dest_user_ids)
-
-        for uid in local_users:
-            results[uid] = yield self.store.get_publicised_groups_for_user(uid)
-
-            # Check AS associated groups for this user - this depends on the
-            # RegExps in the AS registration file (under `users`)
-            for app_service in self.store.get_app_services():
-                results[uid].extend(app_service.get_groups_for_user(uid))
-
-        return {"users": results}
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 512f38e5a6..4ba0042768 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -18,74 +18,57 @@
 """Utilities for interacting with Identity Servers"""
 
 import logging
+import urllib.parse
 
 from canonicaljson import json
+from signedjson.key import decode_verify_key_bytes
+from signedjson.sign import verify_signed_json
+from unpaddedbase64 import decode_base64
 
-from twisted.internet import defer
+from twisted.internet.error import TimeoutError
 
 from synapse.api.errors import (
+    AuthError,
     CodeMessageException,
     Codes,
     HttpResponseException,
     SynapseError,
 )
-from synapse.util.stringutils import random_string
+from synapse.config.emailconfig import ThreepidBehaviour
+from synapse.http.client import SimpleHttpClient
+from synapse.util.hash import sha256_and_url_safe_base64
+from synapse.util.stringutils import assert_valid_client_secret, random_string
 
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
+id_server_scheme = "https://"
+
 
 class IdentityHandler(BaseHandler):
     def __init__(self, hs):
         super(IdentityHandler, self).__init__(hs)
 
-        self.http_client = hs.get_simple_http_client()
+        self.http_client = SimpleHttpClient(hs)
+        # We create a blacklisting instance of SimpleHttpClient for contacting identity
+        # servers specified by clients
+        self.blacklisting_http_client = SimpleHttpClient(
+            hs, ip_blacklist=hs.config.federation_ip_range_blacklist
+        )
         self.federation_http_client = hs.get_http_client()
         self.hs = hs
 
-    def _extract_items_from_creds_dict(self, creds):
-        """
-        Retrieve entries from a "credentials" dictionary
-
-        Args:
-            creds (dict[str, str]): Dictionary of credentials that contain the following keys:
-                * client_secret|clientSecret: A unique secret str provided by the client
-                * id_server|idServer: the domain of the identity server to query
-                * id_access_token: The access token to authenticate to the identity
-                    server with.
-
-        Returns:
-            tuple(str, str, str|None): A tuple containing the client_secret, the id_server,
-                and the id_access_token value if available.
-        """
-        client_secret = creds.get("client_secret") or creds.get("clientSecret")
-        if not client_secret:
-            raise SynapseError(
-                400, "No client_secret in creds", errcode=Codes.MISSING_PARAM
-            )
-
-        id_server = creds.get("id_server") or creds.get("idServer")
-        if not id_server:
-            raise SynapseError(
-                400, "No id_server in creds", errcode=Codes.MISSING_PARAM
-            )
-
-        id_access_token = creds.get("id_access_token")
-        return client_secret, id_server, id_access_token
-
-    @defer.inlineCallbacks
-    def threepid_from_creds(self, id_server, creds):
+    async def threepid_from_creds(self, id_server, creds):
         """
         Retrieve and validate a threepid identifier from a "credentials" dictionary against a
         given identity server
 
         Args:
-            id_server (str|None): The identity server to validate 3PIDs against. If None,
-                we will attempt to extract id_server creds
+            id_server (str): The identity server to validate 3PIDs against. Must be a
+                complete URL including the protocol (http(s)://)
 
             creds (dict[str, str]): Dictionary containing the following keys:
-                * id_server|idServer: An optional domain name of an identity server
                 * client_secret|clientSecret: A unique secret str provided by the client
                 * sid: The ID of the validation session
 
@@ -99,56 +82,65 @@ class IdentityHandler(BaseHandler):
             raise SynapseError(
                 400, "Missing param client_secret in creds", errcode=Codes.MISSING_PARAM
             )
+        assert_valid_client_secret(client_secret)
+
         session_id = creds.get("sid")
         if not session_id:
             raise SynapseError(
                 400, "Missing param session_id in creds", errcode=Codes.MISSING_PARAM
             )
-        if not id_server:
-            # Attempt to get the id_server from the creds dict
-            id_server = creds.get("id_server") or creds.get("idServer")
-            if not id_server:
-                raise SynapseError(
-                    400, "Missing param id_server in creds", errcode=Codes.MISSING_PARAM
-                )
 
         query_params = {"sid": session_id, "client_secret": client_secret}
 
-        url = "https://%s%s" % (
-            id_server,
-            "/_matrix/identity/api/v1/3pid/getValidated3pid",
-        )
+        url = id_server + "/_matrix/identity/api/v1/3pid/getValidated3pid"
 
-        data = yield self.http_client.get_json(url, query_params)
-        return data if "medium" in data else None
+        try:
+            data = await self.http_client.get_json(url, query_params)
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+        except HttpResponseException as e:
+            logger.info(
+                "%s returned %i for threepid validation for: %s",
+                id_server,
+                e.code,
+                creds,
+            )
+            return None
+
+        # Old versions of Sydent return a 200 http code even on a failed validation
+        # check. Thus, in addition to the HttpResponseException check above (which
+        # checks for non-200 errors), we need to make sure validation_session isn't
+        # actually an error, identified by the absence of a "medium" key
+        # See https://github.com/matrix-org/sydent/issues/215 for details
+        if "medium" in data:
+            return data
+
+        logger.info("%s reported non-validated threepid: %s", id_server, creds)
+        return None
 
-    @defer.inlineCallbacks
-    def bind_threepid(self, creds, mxid, use_v2=True):
+    async def bind_threepid(
+        self, client_secret, sid, mxid, id_server, id_access_token=None, use_v2=True
+    ):
         """Bind a 3PID to an identity server
 
         Args:
-            creds (dict[str, str]): Dictionary of credentials that contain the following keys:
-                * client_secret|clientSecret: A unique secret str provided by the client
-                * id_server|idServer: the domain of the identity server to query
-                * id_access_token: The access token to authenticate to the identity
-                    server with. Required if use_v2 is true
+            client_secret (str): A unique secret provided by the client
+
+            sid (str): The ID of the validation session
+
             mxid (str): The MXID to bind the 3PID to
-            use_v2 (bool): Whether to use v2 Identity Service API endpoints
+
+            id_server (str): The domain of the identity server to query
+
+            id_access_token (str): The access token to authenticate to the identity
+                server with, if necessary. Required if use_v2 is true
+
+            use_v2 (bool): Whether to use v2 Identity Service API endpoints. Defaults to True
 
         Returns:
             Deferred[dict]: The response from the identity server
         """
-        logger.debug("binding threepid %r to %s", creds, mxid)
-
-        client_secret, id_server, id_access_token = self._extract_items_from_creds_dict(
-            creds
-        )
-
-        sid = creds.get("sid")
-        if not sid:
-            raise SynapseError(
-                400, "No sid in three_pid_creds", errcode=Codes.MISSING_PARAM
-            )
+        logger.debug("Proxying threepid bind request for %s to %s", mxid, id_server)
 
         # If an id_access_token is not supplied, force usage of v1
         if id_access_token is None:
@@ -164,13 +156,14 @@ class IdentityHandler(BaseHandler):
             bind_url = "https://%s/_matrix/identity/api/v1/3pid/bind" % (id_server,)
 
         try:
-            data = yield self.http_client.post_json_get_json(
+            # Use the blacklisting http client as this call is only to identity servers
+            # provided by a client
+            data = await self.blacklisting_http_client.post_json_get_json(
                 bind_url, bind_data, headers=headers
             )
-            logger.debug("bound threepid %r to %s", creds, mxid)
 
             # Remember where we bound the threepid
-            yield self.store.add_user_bound_threepid(
+            await self.store.add_user_bound_threepid(
                 user_id=mxid,
                 medium=data["medium"],
                 address=data["address"],
@@ -182,15 +175,19 @@ class IdentityHandler(BaseHandler):
             if e.code != 404 or not use_v2:
                 logger.error("3PID bind failed with Matrix error: %r", e)
                 raise e.to_synapse_error()
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
         except CodeMessageException as e:
             data = json.loads(e.msg)  # XXX WAT?
             return data
 
         logger.info("Got 404 when POSTing JSON %s, falling back to v1 URL", bind_url)
-        return (yield self.bind_threepid(creds, mxid, use_v2=False))
+        res = await self.bind_threepid(
+            client_secret, sid, mxid, id_server, id_access_token, use_v2=False
+        )
+        return res
 
-    @defer.inlineCallbacks
-    def try_unbind_threepid(self, mxid, threepid):
+    async def try_unbind_threepid(self, mxid, threepid):
         """Attempt to remove a 3PID from an identity server, or if one is not provided, all
         identity servers we're aware the binding is present on
 
@@ -210,7 +207,7 @@ class IdentityHandler(BaseHandler):
         if threepid.get("id_server"):
             id_servers = [threepid["id_server"]]
         else:
-            id_servers = yield self.store.get_id_servers_user_bound(
+            id_servers = await self.store.get_id_servers_user_bound(
                 user_id=mxid, medium=threepid["medium"], address=threepid["address"]
             )
 
@@ -220,14 +217,13 @@ class IdentityHandler(BaseHandler):
 
         changed = True
         for id_server in id_servers:
-            changed &= yield self.try_unbind_threepid_with_id_server(
+            changed &= await self.try_unbind_threepid_with_id_server(
                 mxid, threepid, id_server
             )
 
         return changed
 
-    @defer.inlineCallbacks
-    def try_unbind_threepid_with_id_server(self, mxid, threepid, id_server):
+    async def try_unbind_threepid_with_id_server(self, mxid, threepid, id_server):
         """Removes a binding from an identity server
 
         Args:
@@ -263,18 +259,24 @@ class IdentityHandler(BaseHandler):
         headers = {b"Authorization": auth_headers}
 
         try:
-            yield self.http_client.post_json_get_json(url, content, headers)
+            # Use the blacklisting http client as this call is only to identity servers
+            # provided by a client
+            await self.blacklisting_http_client.post_json_get_json(
+                url, content, headers
+            )
             changed = True
         except HttpResponseException as e:
             changed = False
             if e.code in (400, 404, 501):
                 # The remote server probably doesn't support unbinding (yet)
-                logger.warn("Received %d response while unbinding threepid", e.code)
+                logger.warning("Received %d response while unbinding threepid", e.code)
             else:
                 logger.error("Failed to unbind threepid on identity server: %s", e)
-                raise SynapseError(502, "Failed to contact identity server")
+                raise SynapseError(500, "Failed to contact identity server")
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
 
-        yield self.store.remove_user_bound_threepid(
+        await self.store.remove_user_bound_threepid(
             user_id=mxid,
             medium=threepid["medium"],
             address=threepid["address"],
@@ -283,8 +285,7 @@ class IdentityHandler(BaseHandler):
 
         return changed
 
-    @defer.inlineCallbacks
-    def send_threepid_validation(
+    async def send_threepid_validation(
         self,
         email_address,
         client_secret,
@@ -312,7 +313,7 @@ class IdentityHandler(BaseHandler):
         """
         # Check that this email/client_secret/send_attempt combo is new or
         # greater than what we've seen previously
-        session = yield self.store.get_threepid_validation_session(
+        session = await self.store.get_threepid_validation_session(
             "email", client_secret, address=email_address, validated=False
         )
 
@@ -331,13 +332,22 @@ class IdentityHandler(BaseHandler):
             # Generate a session id
             session_id = random_string(16)
 
+        if next_link:
+            # Manipulate the next_link to add the sid, because the caller won't get
+            # it until we send a response, by which time we've sent the mail.
+            if "?" in next_link:
+                next_link += "&"
+            else:
+                next_link += "?"
+            next_link += "sid=" + urllib.parse.quote(session_id)
+
         # Generate a new validation token
         token = random_string(32)
 
         # Send the mail with the link containing the token, client_secret
         # and session_id
         try:
-            yield send_email_func(email_address, token, client_secret, session_id)
+            await send_email_func(email_address, token, client_secret, session_id)
         except Exception:
             logger.exception(
                 "Error sending threepid validation email to %s", email_address
@@ -348,7 +358,7 @@ class IdentityHandler(BaseHandler):
             self.hs.clock.time_msec() + self.hs.config.email_validation_token_lifetime
         )
 
-        yield self.store.start_or_continue_validation_session(
+        await self.store.start_or_continue_validation_session(
             "email",
             email_address,
             session_id,
@@ -361,8 +371,7 @@ class IdentityHandler(BaseHandler):
 
         return session_id
 
-    @defer.inlineCallbacks
-    def requestEmailToken(
+    async def requestEmailToken(
         self, id_server, email, client_secret, send_attempt, next_link=None
     ):
         """
@@ -389,7 +398,7 @@ class IdentityHandler(BaseHandler):
 
         if self.hs.config.using_identity_server_from_trusted_list:
             # Warn that a deprecated config option is in use
-            logger.warn(
+            logger.warning(
                 'The config option "trust_identity_server_for_password_resets" '
                 'has been replaced by "account_threepid_delegate". '
                 "Please consult the sample config at docs/sample_config.yaml for "
@@ -397,7 +406,7 @@ class IdentityHandler(BaseHandler):
             )
 
         try:
-            data = yield self.http_client.post_json_get_json(
+            data = await self.http_client.post_json_get_json(
                 id_server + "/_matrix/identity/api/v1/validate/email/requestToken",
                 params,
             )
@@ -405,9 +414,10 @@ class IdentityHandler(BaseHandler):
         except HttpResponseException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e.to_synapse_error()
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
 
-    @defer.inlineCallbacks
-    def requestMsisdnToken(
+    async def requestMsisdnToken(
         self,
         id_server,
         country,
@@ -441,7 +451,7 @@ class IdentityHandler(BaseHandler):
 
         if self.hs.config.using_identity_server_from_trusted_list:
             # Warn that a deprecated config option is in use
-            logger.warn(
+            logger.warning(
                 'The config option "trust_identity_server_for_password_resets" '
                 'has been replaced by "account_threepid_delegate". '
                 "Please consult the sample config at docs/sample_config.yaml for "
@@ -449,14 +459,441 @@ class IdentityHandler(BaseHandler):
             )
 
         try:
-            data = yield self.http_client.post_json_get_json(
+            data = await self.http_client.post_json_get_json(
                 id_server + "/_matrix/identity/api/v1/validate/msisdn/requestToken",
                 params,
             )
-            return data
         except HttpResponseException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e.to_synapse_error()
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+
+        assert self.hs.config.public_baseurl
+
+        # we need to tell the client to send the token back to us, since it doesn't
+        # otherwise know where to send it, so add submit_url response parameter
+        # (see also MSC2078)
+        data["submit_url"] = (
+            self.hs.config.public_baseurl
+            + "_matrix/client/unstable/add_threepid/msisdn/submit_token"
+        )
+        return data
+
+    async def validate_threepid_session(self, client_secret, sid):
+        """Validates a threepid session with only the client secret and session ID
+        Tries validating against any configured account_threepid_delegates as well as locally.
+
+        Args:
+            client_secret (str): A secret provided by the client
+
+            sid (str): The ID of the session
+
+        Returns:
+            Dict[str, str|int] if validation was successful, otherwise None
+        """
+        # XXX: We shouldn't need to keep wrapping and unwrapping this value
+        threepid_creds = {"client_secret": client_secret, "sid": sid}
+
+        # We don't actually know which medium this 3PID is. Thus we first assume it's email,
+        # and if validation fails we try msisdn
+        validation_session = None
+
+        # Try to validate as email
+        if self.hs.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+            # Ask our delegated email identity server
+            validation_session = await self.threepid_from_creds(
+                self.hs.config.account_threepid_delegate_email, threepid_creds
+            )
+        elif self.hs.config.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
+            # Get a validated session matching these details
+            validation_session = await self.store.get_threepid_validation_session(
+                "email", client_secret, sid=sid, validated=True
+            )
+
+        if validation_session:
+            return validation_session
+
+        # Try to validate as msisdn
+        if self.hs.config.account_threepid_delegate_msisdn:
+            # Ask our delegated msisdn identity server
+            validation_session = await self.threepid_from_creds(
+                self.hs.config.account_threepid_delegate_msisdn, threepid_creds
+            )
+
+        return validation_session
+
+    async def proxy_msisdn_submit_token(self, id_server, client_secret, sid, token):
+        """Proxy a POST submitToken request to an identity server for verification purposes
+
+        Args:
+            id_server (str): The identity server URL to contact
+
+            client_secret (str): Secret provided by the client
+
+            sid (str): The ID of the session
+
+            token (str): The verification token
+
+        Raises:
+            SynapseError: If we failed to contact the identity server
+
+        Returns:
+            Deferred[dict]: The response dict from the identity server
+        """
+        body = {"client_secret": client_secret, "sid": sid, "token": token}
+
+        try:
+            return await self.http_client.post_json_get_json(
+                id_server + "/_matrix/identity/api/v1/validate/msisdn/submitToken",
+                body,
+            )
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+        except HttpResponseException as e:
+            logger.warning("Error contacting msisdn account_threepid_delegate: %s", e)
+            raise SynapseError(400, "Error contacting the identity server")
+
+    async def lookup_3pid(self, id_server, medium, address, id_access_token=None):
+        """Looks up a 3pid in the passed identity server.
+
+        Args:
+            id_server (str): The server name (including port, if required)
+                of the identity server to use.
+            medium (str): The type of the third party identifier (e.g. "email").
+            address (str): The third party identifier (e.g. "foo@example.com").
+            id_access_token (str|None): The access token to authenticate to the identity
+                server with
+
+        Returns:
+            str|None: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        if id_access_token is not None:
+            try:
+                results = await self._lookup_3pid_v2(
+                    id_server, id_access_token, medium, address
+                )
+                return results
+
+            except Exception as e:
+                # Catch HttpResponseExcept for a non-200 response code
+                # Check if this identity server does not know about v2 lookups
+                if isinstance(e, HttpResponseException) and e.code == 404:
+                    # This is an old identity server that does not yet support v2 lookups
+                    logger.warning(
+                        "Attempted v2 lookup on v1 identity server %s. Falling "
+                        "back to v1",
+                        id_server,
+                    )
+                else:
+                    logger.warning("Error when looking up hashing details: %s", e)
+                    return None
+
+        return await self._lookup_3pid_v1(id_server, medium, address)
+
+    async def _lookup_3pid_v1(self, id_server, medium, address):
+        """Looks up a 3pid in the passed identity server using v1 lookup.
+
+        Args:
+            id_server (str): The server name (including port, if required)
+                of the identity server to use.
+            medium (str): The type of the third party identifier (e.g. "email").
+            address (str): The third party identifier (e.g. "foo@example.com").
+
+        Returns:
+            str: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        try:
+            data = await self.blacklisting_http_client.get_json(
+                "%s%s/_matrix/identity/api/v1/lookup" % (id_server_scheme, id_server),
+                {"medium": medium, "address": address},
+            )
+
+            if "mxid" in data:
+                if "signatures" not in data:
+                    raise AuthError(401, "No signatures on 3pid binding")
+                await self._verify_any_signature(data, id_server)
+                return data["mxid"]
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+        except IOError as e:
+            logger.warning("Error from v1 identity server lookup: %s" % (e,))
+
+        return None
+
+    async def _lookup_3pid_v2(self, id_server, id_access_token, medium, address):
+        """Looks up a 3pid in the passed identity server using v2 lookup.
+
+        Args:
+            id_server (str): The server name (including port, if required)
+                of the identity server to use.
+            id_access_token (str): The access token to authenticate to the identity server with
+            medium (str): The type of the third party identifier (e.g. "email").
+            address (str): The third party identifier (e.g. "foo@example.com").
+
+        Returns:
+            Deferred[str|None]: the matrix ID of the 3pid, or None if it is not recognised.
+        """
+        # Check what hashing details are supported by this identity server
+        try:
+            hash_details = await self.blacklisting_http_client.get_json(
+                "%s%s/_matrix/identity/v2/hash_details" % (id_server_scheme, id_server),
+                {"access_token": id_access_token},
+            )
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+
+        if not isinstance(hash_details, dict):
+            logger.warning(
+                "Got non-dict object when checking hash details of %s%s: %s",
+                id_server_scheme,
+                id_server,
+                hash_details,
+            )
+            raise SynapseError(
+                400,
+                "Non-dict object from %s%s during v2 hash_details request: %s"
+                % (id_server_scheme, id_server, hash_details),
+            )
+
+        # Extract information from hash_details
+        supported_lookup_algorithms = hash_details.get("algorithms")
+        lookup_pepper = hash_details.get("lookup_pepper")
+        if (
+            not supported_lookup_algorithms
+            or not isinstance(supported_lookup_algorithms, list)
+            or not lookup_pepper
+            or not isinstance(lookup_pepper, str)
+        ):
+            raise SynapseError(
+                400,
+                "Invalid hash details received from identity server %s%s: %s"
+                % (id_server_scheme, id_server, hash_details),
+            )
+
+        # Check if any of the supported lookup algorithms are present
+        if LookupAlgorithm.SHA256 in supported_lookup_algorithms:
+            # Perform a hashed lookup
+            lookup_algorithm = LookupAlgorithm.SHA256
+
+            # Hash address, medium and the pepper with sha256
+            to_hash = "%s %s %s" % (address, medium, lookup_pepper)
+            lookup_value = sha256_and_url_safe_base64(to_hash)
+
+        elif LookupAlgorithm.NONE in supported_lookup_algorithms:
+            # Perform a non-hashed lookup
+            lookup_algorithm = LookupAlgorithm.NONE
+
+            # Combine together plaintext address and medium
+            lookup_value = "%s %s" % (address, medium)
+
+        else:
+            logger.warning(
+                "None of the provided lookup algorithms of %s are supported: %s",
+                id_server,
+                supported_lookup_algorithms,
+            )
+            raise SynapseError(
+                400,
+                "Provided identity server does not support any v2 lookup "
+                "algorithms that this homeserver supports.",
+            )
+
+        # Authenticate with identity server given the access token from the client
+        headers = {"Authorization": create_id_access_token_header(id_access_token)}
+
+        try:
+            lookup_results = await self.blacklisting_http_client.post_json_get_json(
+                "%s%s/_matrix/identity/v2/lookup" % (id_server_scheme, id_server),
+                {
+                    "addresses": [lookup_value],
+                    "algorithm": lookup_algorithm,
+                    "pepper": lookup_pepper,
+                },
+                headers=headers,
+            )
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+        except Exception as e:
+            logger.warning("Error when performing a v2 3pid lookup: %s", e)
+            raise SynapseError(
+                500, "Unknown error occurred during identity server lookup"
+            )
+
+        # Check for a mapping from what we looked up to an MXID
+        if "mappings" not in lookup_results or not isinstance(
+            lookup_results["mappings"], dict
+        ):
+            logger.warning("No results from 3pid lookup")
+            return None
+
+        # Return the MXID if it's available, or None otherwise
+        mxid = lookup_results["mappings"].get(lookup_value)
+        return mxid
+
+    async def _verify_any_signature(self, data, server_hostname):
+        if server_hostname not in data["signatures"]:
+            raise AuthError(401, "No signature from server %s" % (server_hostname,))
+        for key_name, signature in data["signatures"][server_hostname].items():
+            try:
+                key_data = await self.blacklisting_http_client.get_json(
+                    "%s%s/_matrix/identity/api/v1/pubkey/%s"
+                    % (id_server_scheme, server_hostname, key_name)
+                )
+            except TimeoutError:
+                raise SynapseError(500, "Timed out contacting identity server")
+            if "public_key" not in key_data:
+                raise AuthError(
+                    401, "No public key named %s from %s" % (key_name, server_hostname)
+                )
+            verify_signed_json(
+                data,
+                server_hostname,
+                decode_verify_key_bytes(
+                    key_name, decode_base64(key_data["public_key"])
+                ),
+            )
+            return
+
+    async def ask_id_server_for_third_party_invite(
+        self,
+        requester,
+        id_server,
+        medium,
+        address,
+        room_id,
+        inviter_user_id,
+        room_alias,
+        room_avatar_url,
+        room_join_rules,
+        room_name,
+        inviter_display_name,
+        inviter_avatar_url,
+        id_access_token=None,
+    ):
+        """
+        Asks an identity server for a third party invite.
+
+        Args:
+            requester (Requester)
+            id_server (str): hostname + optional port for the identity server.
+            medium (str): The literal string "email".
+            address (str): The third party address being invited.
+            room_id (str): The ID of the room to which the user is invited.
+            inviter_user_id (str): The user ID of the inviter.
+            room_alias (str): An alias for the room, for cosmetic notifications.
+            room_avatar_url (str): The URL of the room's avatar, for cosmetic
+                notifications.
+            room_join_rules (str): The join rules of the email (e.g. "public").
+            room_name (str): The m.room.name of the room.
+            inviter_display_name (str): The current display name of the
+                inviter.
+            inviter_avatar_url (str): The URL of the inviter's avatar.
+            id_access_token (str|None): The access token to authenticate to the identity
+                server with
+
+        Returns:
+            A deferred tuple containing:
+                token (str): The token which must be signed to prove authenticity.
+                public_keys ([{"public_key": str, "key_validity_url": str}]):
+                    public_key is a base64-encoded ed25519 public key.
+                fallback_public_key: One element from public_keys.
+                display_name (str): A user-friendly name to represent the invited
+                    user.
+        """
+        invite_config = {
+            "medium": medium,
+            "address": address,
+            "room_id": room_id,
+            "room_alias": room_alias,
+            "room_avatar_url": room_avatar_url,
+            "room_join_rules": room_join_rules,
+            "room_name": room_name,
+            "sender": inviter_user_id,
+            "sender_display_name": inviter_display_name,
+            "sender_avatar_url": inviter_avatar_url,
+        }
+
+        # Add the identity service access token to the JSON body and use the v2
+        # Identity Service endpoints if id_access_token is present
+        data = None
+        base_url = "%s%s/_matrix/identity" % (id_server_scheme, id_server)
+
+        if id_access_token:
+            key_validity_url = "%s%s/_matrix/identity/v2/pubkey/isvalid" % (
+                id_server_scheme,
+                id_server,
+            )
+
+            # Attempt a v2 lookup
+            url = base_url + "/v2/store-invite"
+            try:
+                data = await self.blacklisting_http_client.post_json_get_json(
+                    url,
+                    invite_config,
+                    {"Authorization": create_id_access_token_header(id_access_token)},
+                )
+            except TimeoutError:
+                raise SynapseError(500, "Timed out contacting identity server")
+            except HttpResponseException as e:
+                if e.code != 404:
+                    logger.info("Failed to POST %s with JSON: %s", url, e)
+                    raise e
+
+        if data is None:
+            key_validity_url = "%s%s/_matrix/identity/api/v1/pubkey/isvalid" % (
+                id_server_scheme,
+                id_server,
+            )
+            url = base_url + "/api/v1/store-invite"
+
+            try:
+                data = await self.blacklisting_http_client.post_json_get_json(
+                    url, invite_config
+                )
+            except TimeoutError:
+                raise SynapseError(500, "Timed out contacting identity server")
+            except HttpResponseException as e:
+                logger.warning(
+                    "Error trying to call /store-invite on %s%s: %s",
+                    id_server_scheme,
+                    id_server,
+                    e,
+                )
+
+            if data is None:
+                # Some identity servers may only support application/x-www-form-urlencoded
+                # types. This is especially true with old instances of Sydent, see
+                # https://github.com/matrix-org/sydent/pull/170
+                try:
+                    data = await self.blacklisting_http_client.post_urlencoded_get_json(
+                        url, invite_config
+                    )
+                except HttpResponseException as e:
+                    logger.warning(
+                        "Error calling /store-invite on %s%s with fallback "
+                        "encoding: %s",
+                        id_server_scheme,
+                        id_server,
+                        e,
+                    )
+                    raise e
+
+        # TODO: Check for success
+        token = data["token"]
+        public_keys = data.get("public_keys", [])
+        if "public_key" in data:
+            fallback_public_key = {
+                "public_key": data["public_key"],
+                "key_validity_url": key_validity_url,
+            }
+        else:
+            fallback_public_key = public_keys[0]
+
+        if not public_keys:
+            public_keys.append(fallback_public_key)
+        display_name = data["display_name"]
+        return token, public_keys, fallback_public_key, display_name
 
 
 def create_id_access_token_header(id_access_token):
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index f991efeee3..f88bad5f25 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -18,7 +18,7 @@ import logging
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import AuthError, Codes, SynapseError
+from synapse.api.errors import SynapseError
 from synapse.events.validator import EventValidator
 from synapse.handlers.presence import format_user_presence_state
 from synapse.logging.context import make_deferred_yieldable, run_in_background
@@ -26,7 +26,7 @@ from synapse.streams.config import PaginationConfig
 from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
 from synapse.util.async_helpers import concurrently_execute
-from synapse.util.caches.snapshot_cache import SnapshotCache
+from synapse.util.caches.response_cache import ResponseCache
 from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
@@ -41,8 +41,10 @@ class InitialSyncHandler(BaseHandler):
         self.state = hs.get_state_handler()
         self.clock = hs.get_clock()
         self.validator = EventValidator()
-        self.snapshot_cache = SnapshotCache()
+        self.snapshot_cache = ResponseCache(hs, "initial_sync_cache")
         self._event_serializer = hs.get_event_client_serializer()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
 
     def snapshot_all_rooms(
         self,
@@ -77,21 +79,17 @@ class InitialSyncHandler(BaseHandler):
             as_client_event,
             include_archived,
         )
-        now_ms = self.clock.time_msec()
-        result = self.snapshot_cache.get(now_ms, key)
-        if result is not None:
-            return result
 
-        return self.snapshot_cache.set(
-            now_ms,
+        return self.snapshot_cache.wrap(
             key,
-            self._snapshot_all_rooms(
-                user_id, pagin_config, as_client_event, include_archived
-            ),
+            self._snapshot_all_rooms,
+            user_id,
+            pagin_config,
+            as_client_event,
+            include_archived,
         )
 
-    @defer.inlineCallbacks
-    def _snapshot_all_rooms(
+    async def _snapshot_all_rooms(
         self,
         user_id=None,
         pagin_config=None,
@@ -103,7 +101,7 @@ class InitialSyncHandler(BaseHandler):
         if include_archived:
             memberships.append(Membership.LEAVE)
 
-        room_list = yield self.store.get_rooms_for_user_where_membership_is(
+        room_list = await self.store.get_rooms_for_local_user_where_membership_is(
             user_id=user_id, membership_list=memberships
         )
 
@@ -111,33 +109,32 @@ class InitialSyncHandler(BaseHandler):
 
         rooms_ret = []
 
-        now_token = yield self.hs.get_event_sources().get_current_token()
+        now_token = await self.hs.get_event_sources().get_current_token()
 
         presence_stream = self.hs.get_event_sources().sources["presence"]
         pagination_config = PaginationConfig(from_token=now_token)
-        presence, _ = yield presence_stream.get_pagination_rows(
+        presence, _ = await presence_stream.get_pagination_rows(
             user, pagination_config.get_source_config("presence"), None
         )
 
         receipt_stream = self.hs.get_event_sources().sources["receipt"]
-        receipt, _ = yield receipt_stream.get_pagination_rows(
+        receipt, _ = await receipt_stream.get_pagination_rows(
             user, pagination_config.get_source_config("receipt"), None
         )
 
-        tags_by_room = yield self.store.get_tags_for_user(user_id)
+        tags_by_room = await self.store.get_tags_for_user(user_id)
 
-        account_data, account_data_by_room = (
-            yield self.store.get_account_data_for_user(user_id)
+        account_data, account_data_by_room = await self.store.get_account_data_for_user(
+            user_id
         )
 
-        public_room_ids = yield self.store.get_public_room_ids()
+        public_room_ids = await self.store.get_public_room_ids()
 
         limit = pagin_config.limit
         if limit is None:
             limit = 10
 
-        @defer.inlineCallbacks
-        def handle_room(event):
+        async def handle_room(event):
             d = {
                 "room_id": event.room_id,
                 "membership": event.membership,
@@ -150,8 +147,8 @@ class InitialSyncHandler(BaseHandler):
                 time_now = self.clock.time_msec()
                 d["inviter"] = event.sender
 
-                invite_event = yield self.store.get_event(event.event_id)
-                d["invite"] = yield self._event_serializer.serialize_event(
+                invite_event = await self.store.get_event(event.event_id)
+                d["invite"] = await self._event_serializer.serialize_event(
                     invite_event, time_now, as_client_event
                 )
 
@@ -169,13 +166,13 @@ class InitialSyncHandler(BaseHandler):
                 elif event.membership == Membership.LEAVE:
                     room_end_token = "s%d" % (event.stream_ordering,)
                     deferred_room_state = run_in_background(
-                        self.store.get_state_for_events, [event.event_id]
+                        self.state_store.get_state_for_events, [event.event_id]
                     )
                     deferred_room_state.addCallback(
                         lambda states: states[event.event_id]
                     )
 
-                (messages, token), current_state = yield make_deferred_yieldable(
+                (messages, token), current_state = await make_deferred_yieldable(
                     defer.gatherResults(
                         [
                             run_in_background(
@@ -189,7 +186,9 @@ class InitialSyncHandler(BaseHandler):
                     )
                 ).addErrback(unwrapFirstError)
 
-                messages = yield filter_events_for_client(self.store, user_id, messages)
+                messages = await filter_events_for_client(
+                    self.storage, user_id, messages
+                )
 
                 start_token = now_token.copy_and_replace("room_key", token)
                 end_token = now_token.copy_and_replace("room_key", room_end_token)
@@ -197,7 +196,7 @@ class InitialSyncHandler(BaseHandler):
 
                 d["messages"] = {
                     "chunk": (
-                        yield self._event_serializer.serialize_events(
+                        await self._event_serializer.serialize_events(
                             messages, time_now=time_now, as_client_event=as_client_event
                         )
                     ),
@@ -205,7 +204,7 @@ class InitialSyncHandler(BaseHandler):
                     "end": end_token.to_string(),
                 }
 
-                d["state"] = yield self._event_serializer.serialize_events(
+                d["state"] = await self._event_serializer.serialize_events(
                     current_state.values(),
                     time_now=time_now,
                     as_client_event=as_client_event,
@@ -228,7 +227,7 @@ class InitialSyncHandler(BaseHandler):
             except Exception:
                 logger.exception("Failed to get snapshot")
 
-        yield concurrently_execute(handle_room, room_list, 10)
+        await concurrently_execute(handle_room, room_list, 10)
 
         account_data_events = []
         for account_data_type, content in account_data.items():
@@ -252,8 +251,7 @@ class InitialSyncHandler(BaseHandler):
 
         return ret
 
-    @defer.inlineCallbacks
-    def room_initial_sync(self, requester, room_id, pagin_config=None):
+    async def room_initial_sync(self, requester, room_id, pagin_config=None):
         """Capture the a snapshot of a room. If user is currently a member of
         the room this will be what is currently in the room. If the user left
         the room this will be what was in the room when they left.
@@ -270,32 +268,35 @@ class InitialSyncHandler(BaseHandler):
             A JSON serialisable dict with the snapshot of the room.
         """
 
-        blocked = yield self.store.is_room_blocked(room_id)
+        blocked = await self.store.is_room_blocked(room_id)
         if blocked:
             raise SynapseError(403, "This room has been blocked on this server")
 
         user_id = requester.user.to_string()
 
-        membership, member_event_id = yield self._check_in_room_or_world_readable(
-            room_id, user_id
+        (
+            membership,
+            member_event_id,
+        ) = await self.auth.check_user_in_room_or_world_readable(
+            room_id, user_id, allow_departed_users=True,
         )
         is_peeking = member_event_id is None
 
         if membership == Membership.JOIN:
-            result = yield self._room_initial_sync_joined(
+            result = await self._room_initial_sync_joined(
                 user_id, room_id, pagin_config, membership, is_peeking
             )
         elif membership == Membership.LEAVE:
-            result = yield self._room_initial_sync_parted(
+            result = await self._room_initial_sync_parted(
                 user_id, room_id, pagin_config, membership, member_event_id, is_peeking
             )
 
         account_data_events = []
-        tags = yield self.store.get_tags_for_room(user_id, room_id)
+        tags = await self.store.get_tags_for_room(user_id, room_id)
         if tags:
             account_data_events.append({"type": "m.tag", "content": {"tags": tags}})
 
-        account_data = yield self.store.get_account_data_for_room(user_id, room_id)
+        account_data = await self.store.get_account_data_for_room(user_id, room_id)
         for account_data_type, content in account_data.items():
             account_data_events.append({"type": account_data_type, "content": content})
 
@@ -303,11 +304,10 @@ class InitialSyncHandler(BaseHandler):
 
         return result
 
-    @defer.inlineCallbacks
-    def _room_initial_sync_parted(
+    async def _room_initial_sync_parted(
         self, user_id, room_id, pagin_config, membership, member_event_id, is_peeking
     ):
-        room_state = yield self.store.get_state_for_events([member_event_id])
+        room_state = await self.state_store.get_state_for_events([member_event_id])
 
         room_state = room_state[member_event_id]
 
@@ -315,14 +315,14 @@ class InitialSyncHandler(BaseHandler):
         if limit is None:
             limit = 10
 
-        stream_token = yield self.store.get_stream_token_for_event(member_event_id)
+        stream_token = await self.store.get_stream_token_for_event(member_event_id)
 
-        messages, token = yield self.store.get_recent_events_for_room(
+        messages, token = await self.store.get_recent_events_for_room(
             room_id, limit=limit, end_token=stream_token
         )
 
-        messages = yield filter_events_for_client(
-            self.store, user_id, messages, is_peeking=is_peeking
+        messages = await filter_events_for_client(
+            self.storage, user_id, messages, is_peeking=is_peeking
         )
 
         start_token = StreamToken.START.copy_and_replace("room_key", token)
@@ -335,13 +335,13 @@ class InitialSyncHandler(BaseHandler):
             "room_id": room_id,
             "messages": {
                 "chunk": (
-                    yield self._event_serializer.serialize_events(messages, time_now)
+                    await self._event_serializer.serialize_events(messages, time_now)
                 ),
                 "start": start_token.to_string(),
                 "end": end_token.to_string(),
             },
             "state": (
-                yield self._event_serializer.serialize_events(
+                await self._event_serializer.serialize_events(
                     room_state.values(), time_now
                 )
             ),
@@ -349,19 +349,18 @@ class InitialSyncHandler(BaseHandler):
             "receipts": [],
         }
 
-    @defer.inlineCallbacks
-    def _room_initial_sync_joined(
+    async def _room_initial_sync_joined(
         self, user_id, room_id, pagin_config, membership, is_peeking
     ):
-        current_state = yield self.state.get_current_state(room_id=room_id)
+        current_state = await self.state.get_current_state(room_id=room_id)
 
         # TODO: These concurrently
         time_now = self.clock.time_msec()
-        state = yield self._event_serializer.serialize_events(
+        state = await self._event_serializer.serialize_events(
             current_state.values(), time_now
         )
 
-        now_token = yield self.hs.get_event_sources().get_current_token()
+        now_token = await self.hs.get_event_sources().get_current_token()
 
         limit = pagin_config.limit if pagin_config else None
         if limit is None:
@@ -376,28 +375,32 @@ class InitialSyncHandler(BaseHandler):
 
         presence_handler = self.hs.get_presence_handler()
 
-        @defer.inlineCallbacks
-        def get_presence():
+        async def get_presence():
             # If presence is disabled, return an empty list
             if not self.hs.config.use_presence:
                 return []
 
-            states = yield presence_handler.get_states(
-                [m.user_id for m in room_members], as_event=True
+            states = await presence_handler.get_states(
+                [m.user_id for m in room_members]
             )
 
-            return states
+            return [
+                {
+                    "type": EventTypes.Presence,
+                    "content": format_user_presence_state(s, time_now),
+                }
+                for s in states
+            ]
 
-        @defer.inlineCallbacks
-        def get_receipts():
-            receipts = yield self.store.get_linearized_receipts_for_room(
+        async def get_receipts():
+            receipts = await self.store.get_linearized_receipts_for_room(
                 room_id, to_key=now_token.receipt_key
             )
             if not receipts:
                 receipts = []
             return receipts
 
-        presence, receipts, (messages, token) = yield make_deferred_yieldable(
+        presence, receipts, (messages, token) = await make_deferred_yieldable(
             defer.gatherResults(
                 [
                     run_in_background(get_presence),
@@ -413,8 +416,8 @@ class InitialSyncHandler(BaseHandler):
             ).addErrback(unwrapFirstError)
         )
 
-        messages = yield filter_events_for_client(
-            self.store, user_id, messages, is_peeking=is_peeking
+        messages = await filter_events_for_client(
+            self.storage, user_id, messages, is_peeking=is_peeking
         )
 
         start_token = now_token.copy_and_replace("room_key", token)
@@ -426,7 +429,7 @@ class InitialSyncHandler(BaseHandler):
             "room_id": room_id,
             "messages": {
                 "chunk": (
-                    yield self._event_serializer.serialize_events(messages, time_now)
+                    await self._event_serializer.serialize_events(messages, time_now)
                 ),
                 "start": start_token.to_string(),
                 "end": end_token.to_string(),
@@ -439,26 +442,3 @@ class InitialSyncHandler(BaseHandler):
             ret["membership"] = membership
 
         return ret
-
-    @defer.inlineCallbacks
-    def _check_in_room_or_world_readable(self, room_id, user_id):
-        try:
-            # check_user_was_in_room will return the most recent membership
-            # event for the user if:
-            #  * The user is a non-guest user, and was ever in the room
-            #  * The user is a guest user, and has joined the room
-            # else it will throw.
-            member_event = yield self.auth.check_user_was_in_room(room_id, user_id)
-            return member_event.membership, member_event.event_id
-        except AuthError:
-            visibility = yield self.state_handler.get_current_state(
-                room_id, EventTypes.RoomHistoryVisibility, ""
-            )
-            if (
-                visibility
-                and visibility.content["history_visibility"] == "world_readable"
-            ):
-                return Membership.JOIN, None
-            raise AuthError(
-                403, "Guest access not allowed", errcode=Codes.GUEST_ACCESS_FORBIDDEN
-            )
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 1f8272784e..649ca1f08a 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -15,6 +15,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+from typing import Optional, Tuple
 
 from six import iteritems, itervalues, string_types
 
@@ -22,9 +23,16 @@ from canonicaljson import encode_canonical_json, json
 
 from twisted.internet import defer
 from twisted.internet.defer import succeed
+from twisted.internet.interfaces import IDelayedCall
 
 from synapse import event_auth
-from synapse.api.constants import EventTypes, Membership, RelationTypes, UserTypes
+from synapse.api.constants import (
+    EventContentFields,
+    EventTypes,
+    Membership,
+    RelationTypes,
+    UserTypes,
+)
 from synapse.api.errors import (
     AuthError,
     Codes,
@@ -32,14 +40,16 @@ from synapse.api.errors import (
     NotFoundError,
     SynapseError,
 )
-from synapse.api.room_versions import RoomVersions
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersions
 from synapse.api.urls import ConsentURIBuilder
+from synapse.events import EventBase
 from synapse.events.validator import EventValidator
 from synapse.logging.context import run_in_background
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
+from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
 from synapse.storage.state import StateFilter
-from synapse.types import RoomAlias, UserID, create_requester
+from synapse.types import Collection, RoomAlias, UserID, create_requester
 from synapse.util.async_helpers import Linearizer
 from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.metrics import measure_func
@@ -59,7 +69,19 @@ class MessageHandler(object):
         self.clock = hs.get_clock()
         self.state = hs.get_state_handler()
         self.store = hs.get_datastore()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
         self._event_serializer = hs.get_event_client_serializer()
+        self._ephemeral_events_enabled = hs.config.enable_ephemeral_messages
+
+        # The scheduled call to self._expire_event. None if no call is currently
+        # scheduled.
+        self._scheduled_expiry = None  # type: Optional[IDelayedCall]
+
+        if not hs.config.worker_app:
+            run_as_background_process(
+                "_schedule_next_expiry", self._schedule_next_expiry
+            )
 
     @defer.inlineCallbacks
     def get_room_data(
@@ -74,15 +96,18 @@ class MessageHandler(object):
         Raises:
             SynapseError if something went wrong.
         """
-        membership, membership_event_id = yield self.auth.check_in_room_or_world_readable(
-            room_id, user_id
+        (
+            membership,
+            membership_event_id,
+        ) = yield self.auth.check_user_in_room_or_world_readable(
+            room_id, user_id, allow_departed_users=True
         )
 
         if membership == Membership.JOIN:
             data = yield self.state.get_current_state(room_id, event_type, state_key)
         elif membership == Membership.LEAVE:
             key = (event_type, state_key)
-            room_state = yield self.store.get_state_for_events(
+            room_state = yield self.state_store.get_state_for_events(
                 [membership_event_id], StateFilter.from_types([key])
             )
             data = room_state[membership_event_id].get(key)
@@ -135,12 +160,12 @@ class MessageHandler(object):
                 raise NotFoundError("Can't find event for token %s" % (at_token,))
 
             visible_events = yield filter_events_for_client(
-                self.store, user_id, last_events
+                self.storage, user_id, last_events, filter_send_to_client=False
             )
 
             event = last_events[0]
             if visible_events:
-                room_state = yield self.store.get_state_for_events(
+                room_state = yield self.state_store.get_state_for_events(
                     [event.event_id], state_filter=state_filter
                 )
                 room_state = room_state[event.event_id]
@@ -151,8 +176,11 @@ class MessageHandler(object):
                     % (user_id, room_id, at_token),
                 )
         else:
-            membership, membership_event_id = (
-                yield self.auth.check_in_room_or_world_readable(room_id, user_id)
+            (
+                membership,
+                membership_event_id,
+            ) = yield self.auth.check_user_in_room_or_world_readable(
+                room_id, user_id, allow_departed_users=True
             )
 
             if membership == Membership.JOIN:
@@ -161,7 +189,7 @@ class MessageHandler(object):
                 )
                 room_state = yield self.store.get_events(state_ids.values())
             elif membership == Membership.LEAVE:
-                room_state = yield self.store.get_state_for_events(
+                room_state = yield self.state_store.get_state_for_events(
                     [membership_event_id], state_filter=state_filter
                 )
                 room_state = room_state[membership_event_id]
@@ -192,8 +220,8 @@ class MessageHandler(object):
         if not requester.app_service:
             # We check AS auth after fetching the room membership, as it
             # requires us to pull out all joined members anyway.
-            membership, _ = yield self.auth.check_in_room_or_world_readable(
-                room_id, user_id
+            membership, _ = yield self.auth.check_user_in_room_or_world_readable(
+                room_id, user_id, allow_departed_users=True
             )
             if membership != Membership.JOIN:
                 raise NotImplementedError(
@@ -221,24 +249,129 @@ class MessageHandler(object):
             for user_id, profile in iteritems(users_with_profile)
         }
 
+    def maybe_schedule_expiry(self, event):
+        """Schedule the expiry of an event if there's not already one scheduled,
+        or if the one running is for an event that will expire after the provided
+        timestamp.
+
+        This function needs to invalidate the event cache, which is only possible on
+        the master process, and therefore needs to be run on there.
+
+        Args:
+            event (EventBase): The event to schedule the expiry of.
+        """
+
+        expiry_ts = event.content.get(EventContentFields.SELF_DESTRUCT_AFTER)
+        if not isinstance(expiry_ts, int) or event.is_state():
+            return
+
+        # _schedule_expiry_for_event won't actually schedule anything if there's already
+        # a task scheduled for a timestamp that's sooner than the provided one.
+        self._schedule_expiry_for_event(event.event_id, expiry_ts)
+
+    @defer.inlineCallbacks
+    def _schedule_next_expiry(self):
+        """Retrieve the ID and the expiry timestamp of the next event to be expired,
+        and schedule an expiry task for it.
+
+        If there's no event left to expire, set _expiry_scheduled to None so that a
+        future call to save_expiry_ts can schedule a new expiry task.
+        """
+        # Try to get the expiry timestamp of the next event to expire.
+        res = yield self.store.get_next_event_to_expire()
+        if res:
+            event_id, expiry_ts = res
+            self._schedule_expiry_for_event(event_id, expiry_ts)
+
+    def _schedule_expiry_for_event(self, event_id, expiry_ts):
+        """Schedule an expiry task for the provided event if there's not already one
+        scheduled at a timestamp that's sooner than the provided one.
+
+        Args:
+            event_id (str): The ID of the event to expire.
+            expiry_ts (int): The timestamp at which to expire the event.
+        """
+        if self._scheduled_expiry:
+            # If the provided timestamp refers to a time before the scheduled time of the
+            # next expiry task, cancel that task and reschedule it for this timestamp.
+            next_scheduled_expiry_ts = self._scheduled_expiry.getTime() * 1000
+            if expiry_ts < next_scheduled_expiry_ts:
+                self._scheduled_expiry.cancel()
+            else:
+                return
+
+        # Figure out how many seconds we need to wait before expiring the event.
+        now_ms = self.clock.time_msec()
+        delay = (expiry_ts - now_ms) / 1000
+
+        # callLater doesn't support negative delays, so trim the delay to 0 if we're
+        # in that case.
+        if delay < 0:
+            delay = 0
+
+        logger.info("Scheduling expiry for event %s in %.3fs", event_id, delay)
+
+        self._scheduled_expiry = self.clock.call_later(
+            delay,
+            run_as_background_process,
+            "_expire_event",
+            self._expire_event,
+            event_id,
+        )
+
+    @defer.inlineCallbacks
+    def _expire_event(self, event_id):
+        """Retrieve and expire an event that needs to be expired from the database.
+
+        If the event doesn't exist in the database, log it and delete the expiry date
+        from the database (so that we don't try to expire it again).
+        """
+        assert self._ephemeral_events_enabled
+
+        self._scheduled_expiry = None
+
+        logger.info("Expiring event %s", event_id)
+
+        try:
+            # Expire the event if we know about it. This function also deletes the expiry
+            # date from the database in the same database transaction.
+            yield self.store.expire_event(event_id)
+        except Exception as e:
+            logger.error("Could not expire event %s: %r", event_id, e)
+
+        # Schedule the expiry of the next event to expire.
+        yield self._schedule_next_expiry()
+
+
+# The duration (in ms) after which rooms should be removed
+# `_rooms_to_exclude_from_dummy_event_insertion` (with the effect that we will try
+# to generate a dummy event for them once more)
+#
+_DUMMY_EVENT_ROOM_EXCLUSION_EXPIRY = 7 * 24 * 60 * 60 * 1000
+
 
 class EventCreationHandler(object):
     def __init__(self, hs):
         self.hs = hs
         self.auth = hs.get_auth()
         self.store = hs.get_datastore()
+        self.storage = hs.get_storage()
         self.state = hs.get_state_handler()
         self.clock = hs.get_clock()
         self.validator = EventValidator()
         self.profile_handler = hs.get_profile_handler()
         self.event_builder_factory = hs.get_event_builder_factory()
         self.server_name = hs.hostname
-        self.ratelimiter = hs.get_ratelimiter()
         self.notifier = hs.get_notifier()
         self.config = hs.config
         self.require_membership_for_aliases = hs.config.require_membership_for_aliases
+        self._is_event_writer = (
+            self.config.worker.writers.events == hs.get_instance_name()
+        )
 
-        self.send_event_to_master = ReplicationSendEventRestServlet.make_client(hs)
+        self.room_invite_state_types = self.hs.config.room_invite_state_types
+
+        self.send_event = ReplicationSendEventRestServlet.make_client(hs)
 
         # This is only used to get at ratelimit function, and maybe_kick_guest_users
         self.base_handler = BaseHandler(hs)
@@ -258,6 +391,13 @@ class EventCreationHandler(object):
             self.config.block_events_without_consent_error
         )
 
+        # Rooms which should be excluded from dummy insertion. (For instance,
+        # those without local users who can send events into the room).
+        #
+        # map from room id to time-of-last-attempt.
+        #
+        self._rooms_to_exclude_from_dummy_event_insertion = {}  # type: dict[str, int]
+
         # we need to construct a ConsentURIBuilder here, as it checks that the necessary
         # config options, but *only* if we have a configuration for which we are
         # going to need it.
@@ -276,6 +416,12 @@ class EventCreationHandler(object):
                 5 * 60 * 1000,
             )
 
+        self._message_handler = hs.get_message_handler()
+
+        self._ephemeral_events_enabled = hs.config.enable_ephemeral_messages
+
+        self._dummy_events_threshold = hs.config.dummy_events_threshold
+
     @defer.inlineCallbacks
     def create_event(
         self,
@@ -283,7 +429,7 @@ class EventCreationHandler(object):
         event_dict,
         token_id=None,
         txn_id=None,
-        prev_events_and_hashes=None,
+        prev_event_ids: Optional[Collection[str]] = None,
         require_consent=True,
     ):
         """
@@ -300,10 +446,9 @@ class EventCreationHandler(object):
             token_id (str)
             txn_id (str)
 
-            prev_events_and_hashes (list[(str, dict[str, str], int)]|None):
+            prev_event_ids:
                 the forward extremities to use as the prev_events for the
-                new event. For each event, a tuple of (event_id, hashes, depth)
-                where *hashes* is a map from algorithm to hash.
+                new event.
 
                 If None, they will be requested from the database.
 
@@ -321,7 +466,9 @@ class EventCreationHandler(object):
             room_version = event_dict["content"]["room_version"]
         else:
             try:
-                room_version = yield self.store.get_room_version(event_dict["room_id"])
+                room_version = yield self.store.get_room_version_id(
+                    event_dict["room_id"]
+                )
             except NotFoundError:
                 raise AuthError(403, "Unknown room")
 
@@ -340,9 +487,13 @@ class EventCreationHandler(object):
 
                 try:
                     if "displayname" not in content:
-                        content["displayname"] = yield profile.get_displayname(target)
+                        displayname = yield profile.get_displayname(target)
+                        if displayname is not None:
+                            content["displayname"] = displayname
                     if "avatar_url" not in content:
-                        content["avatar_url"] = yield profile.get_avatar_url(target)
+                        avatar_url = yield profile.get_avatar_url(target)
+                        if avatar_url is not None:
+                            content["avatar_url"] = avatar_url
                 except Exception as e:
                     logger.info(
                         "Failed to get profile information for %r: %s", target, e
@@ -359,9 +510,7 @@ class EventCreationHandler(object):
             builder.internal_metadata.txn_id = txn_id
 
         event, context = yield self.create_new_client_event(
-            builder=builder,
-            requester=requester,
-            prev_events_and_hashes=prev_events_and_hashes,
+            builder=builder, requester=requester, prev_event_ids=prev_event_ids,
         )
 
         # In an ideal world we wouldn't need the second part of this condition. However,
@@ -376,7 +525,7 @@ class EventCreationHandler(object):
             # federation as well as those created locally. As of room v3, aliases events
             # can be created by users that are not in the room, therefore we have to
             # tolerate them in event_auth.check().
-            prev_state_ids = yield context.get_prev_state_ids(self.store)
+            prev_state_ids = yield context.get_prev_state_ids()
             prev_event_id = prev_state_ids.get((EventTypes.Member, event.sender))
             prev_event = (
                 yield self.store.get_event(prev_event_id, allow_none=True)
@@ -398,7 +547,7 @@ class EventCreationHandler(object):
                     403, "You must be in the room to create an alias for it"
                 )
 
-        self.validator.validate_new(event)
+        self.validator.validate_new(event, self.config)
 
         return (event, context)
 
@@ -484,8 +633,9 @@ class EventCreationHandler(object):
         msg = self._block_events_without_consent_error % {"consent_uri": consent_uri}
         raise ConsentNotGivenError(msg=msg, consent_uri=consent_uri)
 
-    @defer.inlineCallbacks
-    def send_nonmember_event(self, requester, event, context, ratelimit=True):
+    async def send_nonmember_event(
+        self, requester, event, context, ratelimit=True
+    ) -> int:
         """
         Persists and notifies local clients and federation of an event.
 
@@ -494,6 +644,9 @@ class EventCreationHandler(object):
             context (Context) the context of the event.
             ratelimit (bool): Whether to rate limit this send.
             is_guest (bool): Whether the sender is a guest.
+
+        Return:
+            The stream_id of the persisted event.
         """
         if event.type == EventTypes.Member:
             raise SynapseError(
@@ -505,7 +658,7 @@ class EventCreationHandler(object):
         assert self.hs.is_mine(user), "User must be our own: %s" % (user,)
 
         if event.is_state():
-            prev_state = yield self.deduplicate_state_event(event, context)
+            prev_state = await self.deduplicate_state_event(event, context)
             if prev_state is not None:
                 logger.info(
                     "Not bothering to persist state event %s duplicated by %s",
@@ -514,7 +667,7 @@ class EventCreationHandler(object):
                 )
                 return prev_state
 
-        yield self.handle_new_client_event(
+        return await self.handle_new_client_event(
             requester=requester, event=event, context=context, ratelimit=ratelimit
         )
 
@@ -526,7 +679,7 @@ class EventCreationHandler(object):
         If so, returns the version of the event in context.
         Otherwise, returns None.
         """
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = yield context.get_prev_state_ids()
         prev_event_id = prev_state_ids.get((event.type, event.state_key))
         if not prev_event_id:
             return
@@ -541,10 +694,9 @@ class EventCreationHandler(object):
                 return prev_event
         return
 
-    @defer.inlineCallbacks
-    def create_and_send_nonmember_event(
+    async def create_and_send_nonmember_event(
         self, requester, event_dict, ratelimit=True, txn_id=None
-    ):
+    ) -> Tuple[EventBase, int]:
         """
         Creates an event, then sends it.
 
@@ -556,8 +708,8 @@ class EventCreationHandler(object):
         # a situation where event persistence can't keep up, causing
         # extremities to pile up, which in turn leads to state resolution
         # taking longer.
-        with (yield self.limiter.queue(event_dict["room_id"])):
-            event, context = yield self.create_event(
+        with (await self.limiter.queue(event_dict["room_id"])):
+            event, context = await self.create_event(
                 requester, event_dict, token_id=requester.access_token_id, txn_id=txn_id
             )
 
@@ -567,15 +719,15 @@ class EventCreationHandler(object):
                     spam_error = "Spam is not permitted here"
                 raise SynapseError(403, spam_error, Codes.FORBIDDEN)
 
-            yield self.send_nonmember_event(
+            stream_id = await self.send_nonmember_event(
                 requester, event, context, ratelimit=ratelimit
             )
-        return event
+        return event, stream_id
 
     @measure_func("create_new_client_event")
     @defer.inlineCallbacks
     def create_new_client_event(
-        self, builder, requester=None, prev_events_and_hashes=None
+        self, builder, requester=None, prev_event_ids: Optional[Collection[str]] = None
     ):
         """Create a new event for a local client
 
@@ -584,10 +736,9 @@ class EventCreationHandler(object):
 
             requester (synapse.types.Requester|None):
 
-            prev_events_and_hashes (list[(str, dict[str, str], int)]|None):
+            prev_event_ids:
                 the forward extremities to use as the prev_events for the
-                new event. For each event, a tuple of (event_id, hashes, depth)
-                where *hashes* is a map from algorithm to hash.
+                new event.
 
                 If None, they will be requested from the database.
 
@@ -595,27 +746,20 @@ class EventCreationHandler(object):
             Deferred[(synapse.events.EventBase, synapse.events.snapshot.EventContext)]
         """
 
-        if prev_events_and_hashes is not None:
-            assert len(prev_events_and_hashes) <= 10, (
+        if prev_event_ids is not None:
+            assert len(prev_event_ids) <= 10, (
                 "Attempting to create an event with %i prev_events"
-                % (len(prev_events_and_hashes),)
+                % (len(prev_event_ids),)
             )
         else:
-            prev_events_and_hashes = yield self.store.get_prev_events_for_room(
-                builder.room_id
-            )
-
-        prev_events = [
-            (event_id, prev_hashes)
-            for event_id, prev_hashes, _ in prev_events_and_hashes
-        ]
+            prev_event_ids = yield self.store.get_prev_events_for_room(builder.room_id)
 
-        event = yield builder.build(prev_event_ids=[p for p, _ in prev_events])
+        event = yield builder.build(prev_event_ids=prev_event_ids)
         context = yield self.state.compute_event_context(event)
         if requester:
             context.app_service = requester.app_service
 
-        self.validator.validate_new(event)
+        self.validator.validate_new(event, self.config)
 
         # If this event is an annotation then we check that that the sender
         # can't annotate the same way twice (e.g. stops users from liking an
@@ -636,10 +780,9 @@ class EventCreationHandler(object):
         return (event, context)
 
     @measure_func("handle_new_client_event")
-    @defer.inlineCallbacks
-    def handle_new_client_event(
+    async def handle_new_client_event(
         self, requester, event, context, ratelimit=True, extra_users=[]
-    ):
+    ) -> int:
         """Processes a new event. This includes checking auth, persisting it,
         notifying users, sending to remote servers, etc.
 
@@ -652,6 +795,9 @@ class EventCreationHandler(object):
             context (EventContext)
             ratelimit (bool)
             extra_users (list(UserID)): Any extra users to notify about event
+
+        Return:
+            The stream_id of the persisted event.
         """
 
         if event.is_state() and (event.type, event.state_key) == (
@@ -660,9 +806,9 @@ class EventCreationHandler(object):
         ):
             room_version = event.content.get("room_version", RoomVersions.V1.identifier)
         else:
-            room_version = yield self.store.get_room_version(event.room_id)
+            room_version = await self.store.get_room_version_id(event.room_id)
 
-        event_allowed = yield self.third_party_event_rules.check_event_allowed(
+        event_allowed = await self.third_party_event_rules.check_event_allowed(
             event, context
         )
         if not event_allowed:
@@ -671,9 +817,9 @@ class EventCreationHandler(object):
             )
 
         try:
-            yield self.auth.check_from_context(room_version, event, context)
+            await self.auth.check_from_context(room_version, event, context)
         except AuthError as err:
-            logger.warn("Denying new event %r because %s", event, err)
+            logger.warning("Denying new event %r because %s", event, err)
             raise err
 
         # Ensure that we can round trip before trying to persist in db
@@ -684,15 +830,16 @@ class EventCreationHandler(object):
             logger.exception("Failed to encode content: %r", event.content)
             raise
 
-        yield self.action_generator.handle_push_actions_for_event(event, context)
+        await self.action_generator.handle_push_actions_for_event(event, context)
 
         # reraise does not allow inlineCallbacks to preserve the stacktrace, so we
         # hack around with a try/finally instead.
         success = False
         try:
             # If we're a worker we need to hit out to the master.
-            if self.config.worker_app:
-                yield self.send_event_to_master(
+            if not self._is_event_writer:
+                result = await self.send_event(
+                    instance_name=self.config.worker.writers.events,
                     event_id=event.event_id,
                     store=self.store,
                     requester=requester,
@@ -701,14 +848,17 @@ class EventCreationHandler(object):
                     ratelimit=ratelimit,
                     extra_users=extra_users,
                 )
+                stream_id = result["stream_id"]
+                event.internal_metadata.stream_ordering = stream_id
                 success = True
-                return
+                return stream_id
 
-            yield self.persist_and_notify_client_event(
+            stream_id = await self.persist_and_notify_client_event(
                 requester, event, context, ratelimit=ratelimit, extra_users=extra_users
             )
 
             success = True
+            return stream_id
         finally:
             if not success:
                 # Ensure that we actually remove the entries in the push actions
@@ -718,15 +868,46 @@ class EventCreationHandler(object):
                 )
 
     @defer.inlineCallbacks
-    def persist_and_notify_client_event(
-        self, requester, event, context, ratelimit=True, extra_users=[]
+    def _validate_canonical_alias(
+        self, directory_handler, room_alias_str, expected_room_id
     ):
+        """
+        Ensure that the given room alias points to the expected room ID.
+
+        Args:
+            directory_handler: The directory handler object.
+            room_alias_str: The room alias to check.
+            expected_room_id: The room ID that the alias should point to.
+        """
+        room_alias = RoomAlias.from_string(room_alias_str)
+        try:
+            mapping = yield directory_handler.get_association(room_alias)
+        except SynapseError as e:
+            # Turn M_NOT_FOUND errors into M_BAD_ALIAS errors.
+            if e.errcode == Codes.NOT_FOUND:
+                raise SynapseError(
+                    400,
+                    "Room alias %s does not point to the room" % (room_alias_str,),
+                    Codes.BAD_ALIAS,
+                )
+            raise
+
+        if mapping["room_id"] != expected_room_id:
+            raise SynapseError(
+                400,
+                "Room alias %s does not point to the room" % (room_alias_str,),
+                Codes.BAD_ALIAS,
+            )
+
+    async def persist_and_notify_client_event(
+        self, requester, event, context, ratelimit=True, extra_users=[]
+    ) -> int:
         """Called when we have fully built the event, have already
         calculated the push actions for the event, and checked auth.
 
-        This should only be run on master.
+        This should only be run on the instance in charge of persisting events.
         """
-        assert not self.config.worker_app
+        assert self._is_event_writer
 
         if ratelimit:
             # We check if this is a room admin redacting an event so that we
@@ -735,9 +916,9 @@ class EventCreationHandler(object):
             # user is actually admin or not).
             is_admin_redaction = False
             if event.type == EventTypes.Redaction:
-                original_event = yield self.store.get_event(
+                original_event = await self.store.get_event(
                     event.redacts,
-                    check_redacted=False,
+                    redact_behaviour=EventRedactBehaviour.AS_IS,
                     get_prev_content=False,
                     allow_rejected=False,
                     allow_none=True,
@@ -747,24 +928,52 @@ class EventCreationHandler(object):
                     original_event and event.sender != original_event.sender
                 )
 
-            yield self.base_handler.ratelimit(
+            await self.base_handler.ratelimit(
                 requester, is_admin_redaction=is_admin_redaction
             )
 
-        yield self.base_handler.maybe_kick_guest_users(event, context)
+        await self.base_handler.maybe_kick_guest_users(event, context)
 
         if event.type == EventTypes.CanonicalAlias:
-            # Check the alias is acually valid (at this time at least)
+            # Validate a newly added alias or newly added alt_aliases.
+
+            original_alias = None
+            original_alt_aliases = set()
+
+            original_event_id = event.unsigned.get("replaces_state")
+            if original_event_id:
+                original_event = await self.store.get_event(original_event_id)
+
+                if original_event:
+                    original_alias = original_event.content.get("alias", None)
+                    original_alt_aliases = original_event.content.get("alt_aliases", [])
+
+            # Check the alias is currently valid (if it has changed).
             room_alias_str = event.content.get("alias", None)
-            if room_alias_str:
-                room_alias = RoomAlias.from_string(room_alias_str)
-                directory_handler = self.hs.get_handlers().directory_handler
-                mapping = yield directory_handler.get_association(room_alias)
-
-                if mapping["room_id"] != event.room_id:
-                    raise SynapseError(
-                        400,
-                        "Room alias %s does not point to the room" % (room_alias_str,),
+            directory_handler = self.hs.get_handlers().directory_handler
+            if room_alias_str and room_alias_str != original_alias:
+                await self._validate_canonical_alias(
+                    directory_handler, room_alias_str, event.room_id
+                )
+
+            # Check that alt_aliases is the proper form.
+            alt_aliases = event.content.get("alt_aliases", [])
+            if not isinstance(alt_aliases, (list, tuple)):
+                raise SynapseError(
+                    400, "The alt_aliases property must be a list.", Codes.INVALID_PARAM
+                )
+
+            # If the old version of alt_aliases is of an unknown form,
+            # completely replace it.
+            if not isinstance(original_alt_aliases, (list, tuple)):
+                original_alt_aliases = []
+
+            # Check that each alias is currently valid.
+            new_alt_aliases = set(alt_aliases) - set(original_alt_aliases)
+            if new_alt_aliases:
+                for alias_str in new_alt_aliases:
+                    await self._validate_canonical_alias(
+                        directory_handler, alias_str, event.room_id
                     )
 
         federation_handler = self.hs.get_handlers().federation_handler
@@ -775,16 +984,16 @@ class EventCreationHandler(object):
                 def is_inviter_member_event(e):
                     return e.type == EventTypes.Member and e.sender == event.sender
 
-                current_state_ids = yield context.get_current_state_ids(self.store)
+                current_state_ids = await context.get_current_state_ids()
 
                 state_to_include_ids = [
                     e_id
                     for k, e_id in iteritems(current_state_ids)
-                    if k[0] in self.hs.config.room_invite_state_types
+                    if k[0] in self.room_invite_state_types
                     or k == (EventTypes.Member, event.sender)
                 ]
 
-                state_to_include = yield self.store.get_events(state_to_include_ids)
+                state_to_include = await self.store.get_events(state_to_include_ids)
 
                 event.unsigned["invite_room_state"] = [
                     {
@@ -802,19 +1011,18 @@ class EventCreationHandler(object):
                     # way? If we have been invited by a remote server, we need
                     # to get them to sign the event.
 
-                    returned_invite = yield federation_handler.send_invite(
+                    returned_invite = await federation_handler.send_invite(
                         invitee.domain, event
                     )
-
                     event.unsigned.pop("room_state", None)
 
                     # TODO: Make sure the signatures actually are correct.
                     event.signatures.update(returned_invite.signatures)
 
         if event.type == EventTypes.Redaction:
-            original_event = yield self.store.get_event(
+            original_event = await self.store.get_event(
                 event.redacts,
-                check_redacted=False,
+                redact_behaviour=EventRedactBehaviour.AS_IS,
                 get_prev_content=False,
                 allow_rejected=False,
                 allow_none=True,
@@ -828,15 +1036,19 @@ class EventCreationHandler(object):
                 if original_event.room_id != event.room_id:
                     raise SynapseError(400, "Cannot redact event from a different room")
 
-            prev_state_ids = yield context.get_prev_state_ids(self.store)
-            auth_events_ids = yield self.auth.compute_auth_events(
+            prev_state_ids = await context.get_prev_state_ids()
+            auth_events_ids = await self.auth.compute_auth_events(
                 event, prev_state_ids, for_verification=True
             )
-            auth_events = yield self.store.get_events(auth_events_ids)
+            auth_events = await self.store.get_events(auth_events_ids)
             auth_events = {(e.type, e.state_key): e for e in auth_events.values()}
-            room_version = yield self.store.get_room_version(event.room_id)
 
-            if event_auth.check_redaction(room_version, event, auth_events=auth_events):
+            room_version = await self.store.get_room_version_id(event.room_id)
+            room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
+
+            if event_auth.check_redaction(
+                room_version_obj, event, auth_events=auth_events
+            ):
                 # this user doesn't have 'redact' rights, so we need to do some more
                 # checks on the original event. Let's start by checking the original
                 # event exists.
@@ -850,15 +1062,19 @@ class EventCreationHandler(object):
                 event.internal_metadata.recheck_redaction = False
 
         if event.type == EventTypes.Create:
-            prev_state_ids = yield context.get_prev_state_ids(self.store)
+            prev_state_ids = await context.get_prev_state_ids()
             if prev_state_ids:
                 raise AuthError(403, "Changing the room create event is forbidden")
 
-        (event_stream_id, max_stream_id) = yield self.store.persist_event(
+        event_stream_id, max_stream_id = await self.storage.persistence.persist_event(
             event, context=context
         )
 
-        yield self.pusher_pool.on_new_notifications(event_stream_id, max_stream_id)
+        if self._ephemeral_events_enabled:
+            # If there's an expiry timestamp on the event, schedule its expiry.
+            self._message_handler.maybe_schedule_expiry(event)
+
+        await self.pusher_pool.on_new_notifications(event_stream_id, max_stream_id)
 
         def _notify():
             try:
@@ -875,61 +1091,90 @@ class EventCreationHandler(object):
             # matters as sometimes presence code can take a while.
             run_in_background(self._bump_active_time, requester.user)
 
-    @defer.inlineCallbacks
-    def _bump_active_time(self, user):
+        return event_stream_id
+
+    async def _bump_active_time(self, user):
         try:
             presence = self.hs.get_presence_handler()
-            yield presence.bump_presence_active_time(user)
+            await presence.bump_presence_active_time(user)
         except Exception:
             logger.exception("Error bumping presence active time")
 
-    @defer.inlineCallbacks
-    def _send_dummy_events_to_fill_extremities(self):
+    async def _send_dummy_events_to_fill_extremities(self):
         """Background task to send dummy events into rooms that have a large
         number of extremities
         """
-
-        room_ids = yield self.store.get_rooms_with_many_extremities(
-            min_count=10, limit=5
+        self._expire_rooms_to_exclude_from_dummy_event_insertion()
+        room_ids = await self.store.get_rooms_with_many_extremities(
+            min_count=self._dummy_events_threshold,
+            limit=5,
+            room_id_filter=self._rooms_to_exclude_from_dummy_event_insertion.keys(),
         )
 
         for room_id in room_ids:
             # For each room we need to find a joined member we can use to send
             # the dummy event with.
 
-            prev_events_and_hashes = yield self.store.get_prev_events_for_room(room_id)
-
-            latest_event_ids = (event_id for (event_id, _, _) in prev_events_and_hashes)
+            latest_event_ids = await self.store.get_prev_events_for_room(room_id)
 
-            members = yield self.state.get_current_users_in_room(
+            members = await self.state.get_current_users_in_room(
                 room_id, latest_event_ids=latest_event_ids
             )
+            dummy_event_sent = False
+            for user_id in members:
+                if not self.hs.is_mine_id(user_id):
+                    continue
+                requester = create_requester(user_id)
+                try:
+                    event, context = await self.create_event(
+                        requester,
+                        {
+                            "type": "org.matrix.dummy_event",
+                            "content": {},
+                            "room_id": room_id,
+                            "sender": user_id,
+                        },
+                        prev_event_ids=latest_event_ids,
+                    )
+
+                    event.internal_metadata.proactively_send = False
 
-            user_id = None
-            for member in members:
-                if self.hs.is_mine_id(member):
-                    user_id = member
+                    await self.send_nonmember_event(
+                        requester, event, context, ratelimit=False
+                    )
+                    dummy_event_sent = True
                     break
+                except ConsentNotGivenError:
+                    logger.info(
+                        "Failed to send dummy event into room %s for user %s due to "
+                        "lack of consent. Will try another user" % (room_id, user_id)
+                    )
+                except AuthError:
+                    logger.info(
+                        "Failed to send dummy event into room %s for user %s due to "
+                        "lack of power. Will try another user" % (room_id, user_id)
+                    )
 
-            if not user_id:
-                # We don't have a joined user.
-                # TODO: We should do something here to stop the room from
-                # appearing next time.
-                continue
-
-            requester = create_requester(user_id)
-
-            event, context = yield self.create_event(
-                requester,
-                {
-                    "type": "org.matrix.dummy_event",
-                    "content": {},
-                    "room_id": room_id,
-                    "sender": user_id,
-                },
-                prev_events_and_hashes=prev_events_and_hashes,
+            if not dummy_event_sent:
+                # Did not find a valid user in the room, so remove from future attempts
+                # Exclusion is time limited, so the room will be rechecked in the future
+                # dependent on _DUMMY_EVENT_ROOM_EXCLUSION_EXPIRY
+                logger.info(
+                    "Failed to send dummy event into room %s. Will exclude it from "
+                    "future attempts until cache expires" % (room_id,)
+                )
+                now = self.clock.time_msec()
+                self._rooms_to_exclude_from_dummy_event_insertion[room_id] = now
+
+    def _expire_rooms_to_exclude_from_dummy_event_insertion(self):
+        expire_before = self.clock.time_msec() - _DUMMY_EVENT_ROOM_EXCLUSION_EXPIRY
+        to_expire = set()
+        for room_id, time in self._rooms_to_exclude_from_dummy_event_insertion.items():
+            if time < expire_before:
+                to_expire.add(room_id)
+        for room_id in to_expire:
+            logger.debug(
+                "Expiring room id %s from dummy event insertion exclusion cache",
+                room_id,
             )
-
-            event.internal_metadata.proactively_send = False
-
-            yield self.send_nonmember_event(requester, event, context, ratelimit=False)
+            del self._rooms_to_exclude_from_dummy_event_insertion[room_id]
diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py
new file mode 100644
index 0000000000..9c08eb5399
--- /dev/null
+++ b/synapse/handlers/oidc_handler.py
@@ -0,0 +1,1049 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Quentin Gliech
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import json
+import logging
+from typing import Dict, Generic, List, Optional, Tuple, TypeVar
+from urllib.parse import urlencode
+
+import attr
+import pymacaroons
+from authlib.common.security import generate_token
+from authlib.jose import JsonWebToken
+from authlib.oauth2.auth import ClientAuth
+from authlib.oauth2.rfc6749.parameters import prepare_grant_uri
+from authlib.oidc.core import CodeIDToken, ImplicitIDToken, UserInfo
+from authlib.oidc.discovery import OpenIDProviderMetadata, get_well_known_url
+from jinja2 import Environment, Template
+from pymacaroons.exceptions import (
+    MacaroonDeserializationException,
+    MacaroonInvalidSignatureException,
+)
+from typing_extensions import TypedDict
+
+from twisted.web.client import readBody
+
+from synapse.config import ConfigError
+from synapse.http.server import finish_request
+from synapse.http.site import SynapseRequest
+from synapse.logging.context import make_deferred_yieldable
+from synapse.push.mailer import load_jinja2_templates
+from synapse.server import HomeServer
+from synapse.types import UserID, map_username_to_mxid_localpart
+
+logger = logging.getLogger(__name__)
+
+SESSION_COOKIE_NAME = b"oidc_session"
+
+#: A token exchanged from the token endpoint, as per RFC6749 sec 5.1. and
+#: OpenID.Core sec 3.1.3.3.
+Token = TypedDict(
+    "Token",
+    {
+        "access_token": str,
+        "token_type": str,
+        "id_token": Optional[str],
+        "refresh_token": Optional[str],
+        "expires_in": int,
+        "scope": Optional[str],
+    },
+)
+
+#: A JWK, as per RFC7517 sec 4. The type could be more precise than that, but
+#: there is no real point of doing this in our case.
+JWK = Dict[str, str]
+
+#: A JWK Set, as per RFC7517 sec 5.
+JWKS = TypedDict("JWKS", {"keys": List[JWK]})
+
+
+class OidcError(Exception):
+    """Used to catch errors when calling the token_endpoint
+    """
+
+    def __init__(self, error, error_description=None):
+        self.error = error
+        self.error_description = error_description
+
+    def __str__(self):
+        if self.error_description:
+            return "{}: {}".format(self.error, self.error_description)
+        return self.error
+
+
+class MappingException(Exception):
+    """Used to catch errors when mapping the UserInfo object
+    """
+
+
+class OidcHandler:
+    """Handles requests related to the OpenID Connect login flow.
+    """
+
+    def __init__(self, hs: HomeServer):
+        self._callback_url = hs.config.oidc_callback_url  # type: str
+        self._scopes = hs.config.oidc_scopes  # type: List[str]
+        self._client_auth = ClientAuth(
+            hs.config.oidc_client_id,
+            hs.config.oidc_client_secret,
+            hs.config.oidc_client_auth_method,
+        )  # type: ClientAuth
+        self._client_auth_method = hs.config.oidc_client_auth_method  # type: str
+        self._provider_metadata = OpenIDProviderMetadata(
+            issuer=hs.config.oidc_issuer,
+            authorization_endpoint=hs.config.oidc_authorization_endpoint,
+            token_endpoint=hs.config.oidc_token_endpoint,
+            userinfo_endpoint=hs.config.oidc_userinfo_endpoint,
+            jwks_uri=hs.config.oidc_jwks_uri,
+        )  # type: OpenIDProviderMetadata
+        self._provider_needs_discovery = hs.config.oidc_discover  # type: bool
+        self._user_mapping_provider = hs.config.oidc_user_mapping_provider_class(
+            hs.config.oidc_user_mapping_provider_config
+        )  # type: OidcMappingProvider
+        self._skip_verification = hs.config.oidc_skip_verification  # type: bool
+
+        self._http_client = hs.get_proxied_http_client()
+        self._auth_handler = hs.get_auth_handler()
+        self._registration_handler = hs.get_registration_handler()
+        self._datastore = hs.get_datastore()
+        self._clock = hs.get_clock()
+        self._hostname = hs.hostname  # type: str
+        self._server_name = hs.config.server_name  # type: str
+        self._macaroon_secret_key = hs.config.macaroon_secret_key
+        self._error_template = load_jinja2_templates(
+            hs.config.sso_template_dir, ["sso_error.html"]
+        )[0]
+
+        # identifier for the external_ids table
+        self._auth_provider_id = "oidc"
+
+    def _render_error(
+        self, request, error: str, error_description: Optional[str] = None
+    ) -> None:
+        """Renders the error template and respond with it.
+
+        This is used to show errors to the user. The template of this page can
+        be found under ``synapse/res/templates/sso_error.html``.
+
+        Args:
+            request: The incoming request from the browser.
+                We'll respond with an HTML page describing the error.
+            error: A technical identifier for this error. Those include
+                well-known OAuth2/OIDC error types like invalid_request or
+                access_denied.
+            error_description: A human-readable description of the error.
+        """
+        html_bytes = self._error_template.render(
+            error=error, error_description=error_description
+        ).encode("utf-8")
+
+        request.setResponseCode(400)
+        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+        request.setHeader(b"Content-Length", b"%i" % len(html_bytes))
+        request.write(html_bytes)
+        finish_request(request)
+
+    def _validate_metadata(self):
+        """Verifies the provider metadata.
+
+        This checks the validity of the currently loaded provider. Not
+        everything is checked, only:
+
+          - ``issuer``
+          - ``authorization_endpoint``
+          - ``token_endpoint``
+          - ``response_types_supported`` (checks if "code" is in it)
+          - ``jwks_uri``
+
+        Raises:
+            ValueError: if something in the provider is not valid
+        """
+        # Skip verification to allow non-compliant providers (e.g. issuers not running on a secure origin)
+        if self._skip_verification is True:
+            return
+
+        m = self._provider_metadata
+        m.validate_issuer()
+        m.validate_authorization_endpoint()
+        m.validate_token_endpoint()
+
+        if m.get("token_endpoint_auth_methods_supported") is not None:
+            m.validate_token_endpoint_auth_methods_supported()
+            if (
+                self._client_auth_method
+                not in m["token_endpoint_auth_methods_supported"]
+            ):
+                raise ValueError(
+                    '"{auth_method}" not in "token_endpoint_auth_methods_supported" ({supported!r})'.format(
+                        auth_method=self._client_auth_method,
+                        supported=m["token_endpoint_auth_methods_supported"],
+                    )
+                )
+
+        if m.get("response_types_supported") is not None:
+            m.validate_response_types_supported()
+
+            if "code" not in m["response_types_supported"]:
+                raise ValueError(
+                    '"code" not in "response_types_supported" (%r)'
+                    % (m["response_types_supported"],)
+                )
+
+        # If the openid scope was not requested, we need a userinfo endpoint to fetch user infos
+        if self._uses_userinfo:
+            if m.get("userinfo_endpoint") is None:
+                raise ValueError(
+                    'provider has no "userinfo_endpoint", even though it is required because the "openid" scope is not requested'
+                )
+        else:
+            # If we're not using userinfo, we need a valid jwks to validate the ID token
+            if m.get("jwks") is None:
+                if m.get("jwks_uri") is not None:
+                    m.validate_jwks_uri()
+                else:
+                    raise ValueError('"jwks_uri" must be set')
+
+    @property
+    def _uses_userinfo(self) -> bool:
+        """Returns True if the ``userinfo_endpoint`` should be used.
+
+        This is based on the requested scopes: if the scopes include
+        ``openid``, the provider should give use an ID token containing the
+        user informations. If not, we should fetch them using the
+        ``access_token`` with the ``userinfo_endpoint``.
+        """
+
+        # Maybe that should be user-configurable and not inferred?
+        return "openid" not in self._scopes
+
+    async def load_metadata(self) -> OpenIDProviderMetadata:
+        """Load and validate the provider metadata.
+
+        The values metadatas are discovered if ``oidc_config.discovery`` is
+        ``True`` and then cached.
+
+        Raises:
+            ValueError: if something in the provider is not valid
+
+        Returns:
+            The provider's metadata.
+        """
+        # If we are using the OpenID Discovery documents, it needs to be loaded once
+        # FIXME: should there be a lock here?
+        if self._provider_needs_discovery:
+            url = get_well_known_url(self._provider_metadata["issuer"], external=True)
+            metadata_response = await self._http_client.get_json(url)
+            # TODO: maybe update the other way around to let user override some values?
+            self._provider_metadata.update(metadata_response)
+            self._provider_needs_discovery = False
+
+        self._validate_metadata()
+
+        return self._provider_metadata
+
+    async def load_jwks(self, force: bool = False) -> JWKS:
+        """Load the JSON Web Key Set used to sign ID tokens.
+
+        If we're not using the ``userinfo_endpoint``, user infos are extracted
+        from the ID token, which is a JWT signed by keys given by the provider.
+        The keys are then cached.
+
+        Args:
+            force: Force reloading the keys.
+
+        Returns:
+            The key set
+
+            Looks like this::
+
+                {
+                    'keys': [
+                        {
+                            'kid': 'abcdef',
+                            'kty': 'RSA',
+                            'alg': 'RS256',
+                            'use': 'sig',
+                            'e': 'XXXX',
+                            'n': 'XXXX',
+                        }
+                    ]
+                }
+        """
+        if self._uses_userinfo:
+            # We're not using jwt signing, return an empty jwk set
+            return {"keys": []}
+
+        # First check if the JWKS are loaded in the provider metadata.
+        # It can happen either if the provider gives its JWKS in the discovery
+        # document directly or if it was already loaded once.
+        metadata = await self.load_metadata()
+        jwk_set = metadata.get("jwks")
+        if jwk_set is not None and not force:
+            return jwk_set
+
+        # Loading the JWKS using the `jwks_uri` metadata
+        uri = metadata.get("jwks_uri")
+        if not uri:
+            raise RuntimeError('Missing "jwks_uri" in metadata')
+
+        jwk_set = await self._http_client.get_json(uri)
+
+        # Caching the JWKS in the provider's metadata
+        self._provider_metadata["jwks"] = jwk_set
+        return jwk_set
+
+    async def _exchange_code(self, code: str) -> Token:
+        """Exchange an authorization code for a token.
+
+        This calls the ``token_endpoint`` with the authorization code we
+        received in the callback to exchange it for a token. The call uses the
+        ``ClientAuth`` to authenticate with the client with its ID and secret.
+
+        See:
+           https://tools.ietf.org/html/rfc6749#section-3.2
+           https://openid.net/specs/openid-connect-core-1_0.html#TokenEndpoint
+
+        Args:
+            code: The authorization code we got from the callback.
+
+        Returns:
+            A dict containing various tokens.
+
+            May look like this::
+
+                {
+                    'token_type': 'bearer',
+                    'access_token': 'abcdef',
+                    'expires_in': 3599,
+                    'id_token': 'ghijkl',
+                    'refresh_token': 'mnopqr',
+                }
+
+        Raises:
+            OidcError: when the ``token_endpoint`` returned an error.
+        """
+        metadata = await self.load_metadata()
+        token_endpoint = metadata.get("token_endpoint")
+        headers = {
+            "Content-Type": "application/x-www-form-urlencoded",
+            "User-Agent": self._http_client.user_agent,
+            "Accept": "application/json",
+        }
+
+        args = {
+            "grant_type": "authorization_code",
+            "code": code,
+            "redirect_uri": self._callback_url,
+        }
+        body = urlencode(args, True)
+
+        # Fill the body/headers with credentials
+        uri, headers, body = self._client_auth.prepare(
+            method="POST", uri=token_endpoint, headers=headers, body=body
+        )
+        headers = {k: [v] for (k, v) in headers.items()}
+
+        # Do the actual request
+        # We're not using the SimpleHttpClient util methods as we don't want to
+        # check the HTTP status code and we do the body encoding ourself.
+        response = await self._http_client.request(
+            method="POST", uri=uri, data=body.encode("utf-8"), headers=headers,
+        )
+
+        # This is used in multiple error messages below
+        status = "{code} {phrase}".format(
+            code=response.code, phrase=response.phrase.decode("utf-8")
+        )
+
+        resp_body = await make_deferred_yieldable(readBody(response))
+
+        if response.code >= 500:
+            # In case of a server error, we should first try to decode the body
+            # and check for an error field. If not, we respond with a generic
+            # error message.
+            try:
+                resp = json.loads(resp_body.decode("utf-8"))
+                error = resp["error"]
+                description = resp.get("error_description", error)
+            except (ValueError, KeyError):
+                # Catch ValueError for the JSON decoding and KeyError for the "error" field
+                error = "server_error"
+                description = (
+                    (
+                        'Authorization server responded with a "{status}" error '
+                        "while exchanging the authorization code."
+                    ).format(status=status),
+                )
+
+            raise OidcError(error, description)
+
+        # Since it is a not a 5xx code, body should be a valid JSON. It will
+        # raise if not.
+        resp = json.loads(resp_body.decode("utf-8"))
+
+        if "error" in resp:
+            error = resp["error"]
+            # In case the authorization server responded with an error field,
+            # it should be a 4xx code. If not, warn about it but don't do
+            # anything special and report the original error message.
+            if response.code < 400:
+                logger.debug(
+                    "Invalid response from the authorization server: "
+                    'responded with a "{status}" '
+                    "but body has an error field: {error!r}".format(
+                        status=status, error=resp["error"]
+                    )
+                )
+
+            description = resp.get("error_description", error)
+            raise OidcError(error, description)
+
+        # Now, this should not be an error. According to RFC6749 sec 5.1, it
+        # should be a 200 code. We're a bit more flexible than that, and will
+        # only throw on a 4xx code.
+        if response.code >= 400:
+            description = (
+                'Authorization server responded with a "{status}" error '
+                'but did not include an "error" field in its response.'.format(
+                    status=status
+                )
+            )
+            logger.warning(description)
+            # Body was still valid JSON. Might be useful to log it for debugging.
+            logger.warning("Code exchange response: {resp!r}".format(resp=resp))
+            raise OidcError("server_error", description)
+
+        return resp
+
+    async def _fetch_userinfo(self, token: Token) -> UserInfo:
+        """Fetch user informations from the ``userinfo_endpoint``.
+
+        Args:
+            token: the token given by the ``token_endpoint``.
+                Must include an ``access_token`` field.
+
+        Returns:
+            UserInfo: an object representing the user.
+        """
+        metadata = await self.load_metadata()
+
+        resp = await self._http_client.get_json(
+            metadata["userinfo_endpoint"],
+            headers={"Authorization": ["Bearer {}".format(token["access_token"])]},
+        )
+
+        return UserInfo(resp)
+
+    async def _parse_id_token(self, token: Token, nonce: str) -> UserInfo:
+        """Return an instance of UserInfo from token's ``id_token``.
+
+        Args:
+            token: the token given by the ``token_endpoint``.
+                Must include an ``id_token`` field.
+            nonce: the nonce value originally sent in the initial authorization
+                request. This value should match the one inside the token.
+
+        Returns:
+            An object representing the user.
+        """
+        metadata = await self.load_metadata()
+        claims_params = {
+            "nonce": nonce,
+            "client_id": self._client_auth.client_id,
+        }
+        if "access_token" in token:
+            # If we got an `access_token`, there should be an `at_hash` claim
+            # in the `id_token` that we can check against.
+            claims_params["access_token"] = token["access_token"]
+            claims_cls = CodeIDToken
+        else:
+            claims_cls = ImplicitIDToken
+
+        alg_values = metadata.get("id_token_signing_alg_values_supported", ["RS256"])
+
+        jwt = JsonWebToken(alg_values)
+
+        claim_options = {"iss": {"values": [metadata["issuer"]]}}
+
+        # Try to decode the keys in cache first, then retry by forcing the keys
+        # to be reloaded
+        jwk_set = await self.load_jwks()
+        try:
+            claims = jwt.decode(
+                token["id_token"],
+                key=jwk_set,
+                claims_cls=claims_cls,
+                claims_options=claim_options,
+                claims_params=claims_params,
+            )
+        except ValueError:
+            logger.info("Reloading JWKS after decode error")
+            jwk_set = await self.load_jwks(force=True)  # try reloading the jwks
+            claims = jwt.decode(
+                token["id_token"],
+                key=jwk_set,
+                claims_cls=claims_cls,
+                claims_options=claim_options,
+                claims_params=claims_params,
+            )
+
+        claims.validate(leeway=120)  # allows 2 min of clock skew
+        return UserInfo(claims)
+
+    async def handle_redirect_request(
+        self,
+        request: SynapseRequest,
+        client_redirect_url: bytes,
+        ui_auth_session_id: Optional[str] = None,
+    ) -> str:
+        """Handle an incoming request to /login/sso/redirect
+
+        It returns a redirect to the authorization endpoint with a few
+        parameters:
+
+          - ``client_id``: the client ID set in ``oidc_config.client_id``
+          - ``response_type``: ``code``
+          - ``redirect_uri``: the callback URL ; ``{base url}/_synapse/oidc/callback``
+          - ``scope``: the list of scopes set in ``oidc_config.scopes``
+          - ``state``: a random string
+          - ``nonce``: a random string
+
+        In addition generating a redirect URL, we are setting a cookie with
+        a signed macaroon token containing the state, the nonce and the
+        client_redirect_url params. Those are then checked when the client
+        comes back from the provider.
+
+        Args:
+            request: the incoming request from the browser.
+                We'll respond to it with a redirect and a cookie.
+            client_redirect_url: the URL that we should redirect the client to
+                when everything is done
+            ui_auth_session_id: The session ID of the ongoing UI Auth (or
+                None if this is a login).
+
+        Returns:
+            The redirect URL to the authorization endpoint.
+
+        """
+
+        state = generate_token()
+        nonce = generate_token()
+
+        cookie = self._generate_oidc_session_token(
+            state=state,
+            nonce=nonce,
+            client_redirect_url=client_redirect_url.decode(),
+            ui_auth_session_id=ui_auth_session_id,
+        )
+        request.addCookie(
+            SESSION_COOKIE_NAME,
+            cookie,
+            path="/_synapse/oidc",
+            max_age="3600",
+            httpOnly=True,
+            sameSite="lax",
+        )
+
+        metadata = await self.load_metadata()
+        authorization_endpoint = metadata.get("authorization_endpoint")
+        return prepare_grant_uri(
+            authorization_endpoint,
+            client_id=self._client_auth.client_id,
+            response_type="code",
+            redirect_uri=self._callback_url,
+            scope=self._scopes,
+            state=state,
+            nonce=nonce,
+        )
+
+    async def handle_oidc_callback(self, request: SynapseRequest) -> None:
+        """Handle an incoming request to /_synapse/oidc/callback
+
+        Since we might want to display OIDC-related errors in a user-friendly
+        way, we don't raise SynapseError from here. Instead, we call
+        ``self._render_error`` which displays an HTML page for the error.
+
+        Most of the OpenID Connect logic happens here:
+
+          - first, we check if there was any error returned by the provider and
+            display it
+          - then we fetch the session cookie, decode and verify it
+          - the ``state`` query parameter should match with the one stored in the
+            session cookie
+          - once we known this session is legit, exchange the code with the
+            provider using the ``token_endpoint`` (see ``_exchange_code``)
+          - once we have the token, use it to either extract the UserInfo from
+            the ``id_token`` (``_parse_id_token``), or use the ``access_token``
+            to fetch UserInfo from the ``userinfo_endpoint``
+            (``_fetch_userinfo``)
+          - map those UserInfo to a Matrix user (``_map_userinfo_to_user``) and
+            finish the login
+
+        Args:
+            request: the incoming request from the browser.
+        """
+
+        # The provider might redirect with an error.
+        # In that case, just display it as-is.
+        if b"error" in request.args:
+            # error response from the auth server. see:
+            #  https://tools.ietf.org/html/rfc6749#section-4.1.2.1
+            #  https://openid.net/specs/openid-connect-core-1_0.html#AuthError
+            error = request.args[b"error"][0].decode()
+            description = request.args.get(b"error_description", [b""])[0].decode()
+
+            # Most of the errors returned by the provider could be due by
+            # either the provider misbehaving or Synapse being misconfigured.
+            # The only exception of that is "access_denied", where the user
+            # probably cancelled the login flow. In other cases, log those errors.
+            if error != "access_denied":
+                logger.error("Error from the OIDC provider: %s %s", error, description)
+
+            self._render_error(request, error, description)
+            return
+
+        # otherwise, it is presumably a successful response. see:
+        #   https://tools.ietf.org/html/rfc6749#section-4.1.2
+
+        # Fetch the session cookie
+        session = request.getCookie(SESSION_COOKIE_NAME)  # type: Optional[bytes]
+        if session is None:
+            logger.info("No session cookie found")
+            self._render_error(request, "missing_session", "No session cookie found")
+            return
+
+        # Remove the cookie. There is a good chance that if the callback failed
+        # once, it will fail next time and the code will already be exchanged.
+        # Removing it early avoids spamming the provider with token requests.
+        request.addCookie(
+            SESSION_COOKIE_NAME,
+            b"",
+            path="/_synapse/oidc",
+            expires="Thu, Jan 01 1970 00:00:00 UTC",
+            httpOnly=True,
+            sameSite="lax",
+        )
+
+        # Check for the state query parameter
+        if b"state" not in request.args:
+            logger.info("State parameter is missing")
+            self._render_error(request, "invalid_request", "State parameter is missing")
+            return
+
+        state = request.args[b"state"][0].decode()
+
+        # Deserialize the session token and verify it.
+        try:
+            (
+                nonce,
+                client_redirect_url,
+                ui_auth_session_id,
+            ) = self._verify_oidc_session_token(session, state)
+        except MacaroonDeserializationException as e:
+            logger.exception("Invalid session")
+            self._render_error(request, "invalid_session", str(e))
+            return
+        except MacaroonInvalidSignatureException as e:
+            logger.exception("Could not verify session")
+            self._render_error(request, "mismatching_session", str(e))
+            return
+
+        # Exchange the code with the provider
+        if b"code" not in request.args:
+            logger.info("Code parameter is missing")
+            self._render_error(request, "invalid_request", "Code parameter is missing")
+            return
+
+        logger.debug("Exchanging code")
+        code = request.args[b"code"][0].decode()
+        try:
+            token = await self._exchange_code(code)
+        except OidcError as e:
+            logger.exception("Could not exchange code")
+            self._render_error(request, e.error, e.error_description)
+            return
+
+        logger.debug("Successfully obtained OAuth2 access token")
+
+        # Now that we have a token, get the userinfo, either by decoding the
+        # `id_token` or by fetching the `userinfo_endpoint`.
+        if self._uses_userinfo:
+            logger.debug("Fetching userinfo")
+            try:
+                userinfo = await self._fetch_userinfo(token)
+            except Exception as e:
+                logger.exception("Could not fetch userinfo")
+                self._render_error(request, "fetch_error", str(e))
+                return
+        else:
+            logger.debug("Extracting userinfo from id_token")
+            try:
+                userinfo = await self._parse_id_token(token, nonce=nonce)
+            except Exception as e:
+                logger.exception("Invalid id_token")
+                self._render_error(request, "invalid_token", str(e))
+                return
+
+        # Call the mapper to register/login the user
+        try:
+            user_id = await self._map_userinfo_to_user(userinfo, token)
+        except MappingException as e:
+            logger.exception("Could not map user")
+            self._render_error(request, "mapping_error", str(e))
+            return
+
+        # and finally complete the login
+        if ui_auth_session_id:
+            await self._auth_handler.complete_sso_ui_auth(
+                user_id, ui_auth_session_id, request
+            )
+        else:
+            await self._auth_handler.complete_sso_login(
+                user_id, request, client_redirect_url
+            )
+
+    def _generate_oidc_session_token(
+        self,
+        state: str,
+        nonce: str,
+        client_redirect_url: str,
+        ui_auth_session_id: Optional[str],
+        duration_in_ms: int = (60 * 60 * 1000),
+    ) -> str:
+        """Generates a signed token storing data about an OIDC session.
+
+        When Synapse initiates an authorization flow, it creates a random state
+        and a random nonce. Those parameters are given to the provider and
+        should be verified when the client comes back from the provider.
+        It is also used to store the client_redirect_url, which is used to
+        complete the SSO login flow.
+
+        Args:
+            state: The ``state`` parameter passed to the OIDC provider.
+            nonce: The ``nonce`` parameter passed to the OIDC provider.
+            client_redirect_url: The URL the client gave when it initiated the
+                flow.
+            ui_auth_session_id: The session ID of the ongoing UI Auth (or
+                None if this is a login).
+            duration_in_ms: An optional duration for the token in milliseconds.
+                Defaults to an hour.
+
+        Returns:
+            A signed macaroon token with the session informations.
+        """
+        macaroon = pymacaroons.Macaroon(
+            location=self._server_name, identifier="key", key=self._macaroon_secret_key,
+        )
+        macaroon.add_first_party_caveat("gen = 1")
+        macaroon.add_first_party_caveat("type = session")
+        macaroon.add_first_party_caveat("state = %s" % (state,))
+        macaroon.add_first_party_caveat("nonce = %s" % (nonce,))
+        macaroon.add_first_party_caveat(
+            "client_redirect_url = %s" % (client_redirect_url,)
+        )
+        if ui_auth_session_id:
+            macaroon.add_first_party_caveat(
+                "ui_auth_session_id = %s" % (ui_auth_session_id,)
+            )
+        now = self._clock.time_msec()
+        expiry = now + duration_in_ms
+        macaroon.add_first_party_caveat("time < %d" % (expiry,))
+
+        return macaroon.serialize()
+
+    def _verify_oidc_session_token(
+        self, session: bytes, state: str
+    ) -> Tuple[str, str, Optional[str]]:
+        """Verifies and extract an OIDC session token.
+
+        This verifies that a given session token was issued by this homeserver
+        and extract the nonce and client_redirect_url caveats.
+
+        Args:
+            session: The session token to verify
+            state: The state the OIDC provider gave back
+
+        Returns:
+            The nonce, client_redirect_url, and ui_auth_session_id for this session
+        """
+        macaroon = pymacaroons.Macaroon.deserialize(session)
+
+        v = pymacaroons.Verifier()
+        v.satisfy_exact("gen = 1")
+        v.satisfy_exact("type = session")
+        v.satisfy_exact("state = %s" % (state,))
+        v.satisfy_general(lambda c: c.startswith("nonce = "))
+        v.satisfy_general(lambda c: c.startswith("client_redirect_url = "))
+        # Sometimes there's a UI auth session ID, it seems to be OK to attempt
+        # to always satisfy this.
+        v.satisfy_general(lambda c: c.startswith("ui_auth_session_id = "))
+        v.satisfy_general(self._verify_expiry)
+
+        v.verify(macaroon, self._macaroon_secret_key)
+
+        # Extract the `nonce`, `client_redirect_url`, and maybe the
+        # `ui_auth_session_id` from the token.
+        nonce = self._get_value_from_macaroon(macaroon, "nonce")
+        client_redirect_url = self._get_value_from_macaroon(
+            macaroon, "client_redirect_url"
+        )
+        try:
+            ui_auth_session_id = self._get_value_from_macaroon(
+                macaroon, "ui_auth_session_id"
+            )  # type: Optional[str]
+        except ValueError:
+            ui_auth_session_id = None
+
+        return nonce, client_redirect_url, ui_auth_session_id
+
+    def _get_value_from_macaroon(self, macaroon: pymacaroons.Macaroon, key: str) -> str:
+        """Extracts a caveat value from a macaroon token.
+
+        Args:
+            macaroon: the token
+            key: the key of the caveat to extract
+
+        Returns:
+            The extracted value
+
+        Raises:
+            Exception: if the caveat was not in the macaroon
+        """
+        prefix = key + " = "
+        for caveat in macaroon.caveats:
+            if caveat.caveat_id.startswith(prefix):
+                return caveat.caveat_id[len(prefix) :]
+        raise ValueError("No %s caveat in macaroon" % (key,))
+
+    def _verify_expiry(self, caveat: str) -> bool:
+        prefix = "time < "
+        if not caveat.startswith(prefix):
+            return False
+        expiry = int(caveat[len(prefix) :])
+        now = self._clock.time_msec()
+        return now < expiry
+
+    async def _map_userinfo_to_user(self, userinfo: UserInfo, token: Token) -> str:
+        """Maps a UserInfo object to a mxid.
+
+        UserInfo should have a claim that uniquely identifies users. This claim
+        is usually `sub`, but can be configured with `oidc_config.subject_claim`.
+        It is then used as an `external_id`.
+
+        If we don't find the user that way, we should register the user,
+        mapping the localpart and the display name from the UserInfo.
+
+        If a user already exists with the mxid we've mapped, raise an exception.
+
+        Args:
+            userinfo: an object representing the user
+            token: a dict with the tokens obtained from the provider
+
+        Raises:
+            MappingException: if there was an error while mapping some properties
+
+        Returns:
+            The mxid of the user
+        """
+        try:
+            remote_user_id = self._user_mapping_provider.get_remote_user_id(userinfo)
+        except Exception as e:
+            raise MappingException(
+                "Failed to extract subject from OIDC response: %s" % (e,)
+            )
+
+        logger.info(
+            "Looking for existing mapping for user %s:%s",
+            self._auth_provider_id,
+            remote_user_id,
+        )
+
+        registered_user_id = await self._datastore.get_user_by_external_id(
+            self._auth_provider_id, remote_user_id,
+        )
+
+        if registered_user_id is not None:
+            logger.info("Found existing mapping %s", registered_user_id)
+            return registered_user_id
+
+        try:
+            attributes = await self._user_mapping_provider.map_user_attributes(
+                userinfo, token
+            )
+        except Exception as e:
+            raise MappingException(
+                "Could not extract user attributes from OIDC response: " + str(e)
+            )
+
+        logger.debug(
+            "Retrieved user attributes from user mapping provider: %r", attributes
+        )
+
+        if not attributes["localpart"]:
+            raise MappingException("localpart is empty")
+
+        localpart = map_username_to_mxid_localpart(attributes["localpart"])
+
+        user_id = UserID(localpart, self._hostname)
+        if await self._datastore.get_users_by_id_case_insensitive(user_id.to_string()):
+            # This mxid is taken
+            raise MappingException(
+                "mxid '{}' is already taken".format(user_id.to_string())
+            )
+
+        # It's the first time this user is logging in and the mapped mxid was
+        # not taken, register the user
+        registered_user_id = await self._registration_handler.register_user(
+            localpart=localpart, default_display_name=attributes["display_name"],
+        )
+
+        await self._datastore.record_user_external_id(
+            self._auth_provider_id, remote_user_id, registered_user_id,
+        )
+        return registered_user_id
+
+
+UserAttribute = TypedDict(
+    "UserAttribute", {"localpart": str, "display_name": Optional[str]}
+)
+C = TypeVar("C")
+
+
+class OidcMappingProvider(Generic[C]):
+    """A mapping provider maps a UserInfo object to user attributes.
+
+    It should provide the API described by this class.
+    """
+
+    def __init__(self, config: C):
+        """
+        Args:
+            config: A custom config object from this module, parsed by ``parse_config()``
+        """
+
+    @staticmethod
+    def parse_config(config: dict) -> C:
+        """Parse the dict provided by the homeserver's config
+
+        Args:
+            config: A dictionary containing configuration options for this provider
+
+        Returns:
+            A custom config object for this module
+        """
+        raise NotImplementedError()
+
+    def get_remote_user_id(self, userinfo: UserInfo) -> str:
+        """Get a unique user ID for this user.
+
+        Usually, in an OIDC-compliant scenario, it should be the ``sub`` claim from the UserInfo object.
+
+        Args:
+            userinfo: An object representing the user given by the OIDC provider
+
+        Returns:
+            A unique user ID
+        """
+        raise NotImplementedError()
+
+    async def map_user_attributes(
+        self, userinfo: UserInfo, token: Token
+    ) -> UserAttribute:
+        """Map a ``UserInfo`` objects into user attributes.
+
+        Args:
+            userinfo: An object representing the user given by the OIDC provider
+            token: A dict with the tokens returned by the provider
+
+        Returns:
+            A dict containing the ``localpart`` and (optionally) the ``display_name``
+        """
+        raise NotImplementedError()
+
+
+# Used to clear out "None" values in templates
+def jinja_finalize(thing):
+    return thing if thing is not None else ""
+
+
+env = Environment(finalize=jinja_finalize)
+
+
+@attr.s
+class JinjaOidcMappingConfig:
+    subject_claim = attr.ib()  # type: str
+    localpart_template = attr.ib()  # type: Template
+    display_name_template = attr.ib()  # type: Optional[Template]
+
+
+class JinjaOidcMappingProvider(OidcMappingProvider[JinjaOidcMappingConfig]):
+    """An implementation of a mapping provider based on Jinja templates.
+
+    This is the default mapping provider.
+    """
+
+    def __init__(self, config: JinjaOidcMappingConfig):
+        self._config = config
+
+    @staticmethod
+    def parse_config(config: dict) -> JinjaOidcMappingConfig:
+        subject_claim = config.get("subject_claim", "sub")
+
+        if "localpart_template" not in config:
+            raise ConfigError(
+                "missing key: oidc_config.user_mapping_provider.config.localpart_template"
+            )
+
+        try:
+            localpart_template = env.from_string(config["localpart_template"])
+        except Exception as e:
+            raise ConfigError(
+                "invalid jinja template for oidc_config.user_mapping_provider.config.localpart_template: %r"
+                % (e,)
+            )
+
+        display_name_template = None  # type: Optional[Template]
+        if "display_name_template" in config:
+            try:
+                display_name_template = env.from_string(config["display_name_template"])
+            except Exception as e:
+                raise ConfigError(
+                    "invalid jinja template for oidc_config.user_mapping_provider.config.display_name_template: %r"
+                    % (e,)
+                )
+
+        return JinjaOidcMappingConfig(
+            subject_claim=subject_claim,
+            localpart_template=localpart_template,
+            display_name_template=display_name_template,
+        )
+
+    def get_remote_user_id(self, userinfo: UserInfo) -> str:
+        return userinfo[self._config.subject_claim]
+
+    async def map_user_attributes(
+        self, userinfo: UserInfo, token: Token
+    ) -> UserAttribute:
+        localpart = self._config.localpart_template.render(user=userinfo).strip()
+
+        display_name = None  # type: Optional[str]
+        if self._config.display_name_template is not None:
+            display_name = self._config.display_name_template.render(
+                user=userinfo
+            ).strip()
+
+            if display_name == "":
+                display_name = None
+
+        return UserAttribute(localpart=localpart, display_name=display_name)
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index 5744f4579d..d7442c62a7 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -15,12 +15,15 @@
 # limitations under the License.
 import logging
 
+from six import iteritems
+
 from twisted.internet import defer
 from twisted.python.failure import Failure
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import SynapseError
 from synapse.logging.context import run_in_background
+from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.state import StateFilter
 from synapse.types import RoomStreamToken
 from synapse.util.async_helpers import ReadWriteLock
@@ -69,6 +72,8 @@ class PaginationHandler(object):
         self.hs = hs
         self.auth = hs.get_auth()
         self.store = hs.get_datastore()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
         self.clock = hs.get_clock()
         self._server_name = hs.hostname
 
@@ -78,6 +83,122 @@ class PaginationHandler(object):
         self._purges_by_id = {}
         self._event_serializer = hs.get_event_client_serializer()
 
+        self._retention_default_max_lifetime = hs.config.retention_default_max_lifetime
+
+        if hs.config.retention_enabled:
+            # Run the purge jobs described in the configuration file.
+            for job in hs.config.retention_purge_jobs:
+                logger.info("Setting up purge job with config: %s", job)
+
+                self.clock.looping_call(
+                    run_as_background_process,
+                    job["interval"],
+                    "purge_history_for_rooms_in_range",
+                    self.purge_history_for_rooms_in_range,
+                    job["shortest_max_lifetime"],
+                    job["longest_max_lifetime"],
+                )
+
+    @defer.inlineCallbacks
+    def purge_history_for_rooms_in_range(self, min_ms, max_ms):
+        """Purge outdated events from rooms within the given retention range.
+
+        If a default retention policy is defined in the server's configuration and its
+        'max_lifetime' is within this range, also targets rooms which don't have a
+        retention policy.
+
+        Args:
+            min_ms (int|None): Duration in milliseconds that define the lower limit of
+                the range to handle (exclusive). If None, it means that the range has no
+                lower limit.
+            max_ms (int|None): Duration in milliseconds that define the upper limit of
+                the range to handle (inclusive). If None, it means that the range has no
+                upper limit.
+        """
+        # We want the storage layer to to include rooms with no retention policy in its
+        # return value only if a default retention policy is defined in the server's
+        # configuration and that policy's 'max_lifetime' is either lower (or equal) than
+        # max_ms or higher than min_ms (or both).
+        if self._retention_default_max_lifetime is not None:
+            include_null = True
+
+            if min_ms is not None and min_ms >= self._retention_default_max_lifetime:
+                # The default max_lifetime is lower than (or equal to) min_ms.
+                include_null = False
+
+            if max_ms is not None and max_ms < self._retention_default_max_lifetime:
+                # The default max_lifetime is higher than max_ms.
+                include_null = False
+        else:
+            include_null = False
+
+        logger.info(
+            "[purge] Running purge job for %s < max_lifetime <= %s (include NULLs = %s)",
+            min_ms,
+            max_ms,
+            include_null,
+        )
+
+        rooms = yield self.store.get_rooms_for_retention_period_in_range(
+            min_ms, max_ms, include_null
+        )
+
+        logger.debug("[purge] Rooms to purge: %s", rooms)
+
+        for room_id, retention_policy in iteritems(rooms):
+            logger.info("[purge] Attempting to purge messages in room %s", room_id)
+
+            if room_id in self._purges_in_progress_by_room:
+                logger.warning(
+                    "[purge] not purging room %s as there's an ongoing purge running"
+                    " for this room",
+                    room_id,
+                )
+                continue
+
+            max_lifetime = retention_policy["max_lifetime"]
+
+            if max_lifetime is None:
+                # If max_lifetime is None, it means that include_null equals True,
+                # therefore we can safely assume that there is a default policy defined
+                # in the server's configuration.
+                max_lifetime = self._retention_default_max_lifetime
+
+            # Figure out what token we should start purging at.
+            ts = self.clock.time_msec() - max_lifetime
+
+            stream_ordering = yield self.store.find_first_stream_ordering_after_ts(ts)
+
+            r = yield self.store.get_room_event_before_stream_ordering(
+                room_id, stream_ordering,
+            )
+            if not r:
+                logger.warning(
+                    "[purge] purging events not possible: No event found "
+                    "(ts %i => stream_ordering %i)",
+                    ts,
+                    stream_ordering,
+                )
+                continue
+
+            (stream, topo, _event_id) = r
+            token = "t%d-%d" % (topo, stream)
+
+            purge_id = random_string(16)
+
+            self._purges_by_id[purge_id] = PurgeStatus()
+
+            logger.info(
+                "Starting purging events in room %s (purge_id %s)" % (room_id, purge_id)
+            )
+
+            # We want to purge everything, including local events, and to run the purge in
+            # the background so that it's not blocking any other operation apart from
+            # other purges in the same room.
+            run_as_background_process(
+                "_purge_history", self._purge_history, purge_id, room_id, token, True,
+            )
+
     def start_purge_history(self, room_id, token, delete_local_events=False):
         """Start off a history purge on a room.
 
@@ -125,7 +246,9 @@ class PaginationHandler(object):
         self._purges_in_progress_by_room.add(room_id)
         try:
             with (yield self.pagination_lock.write(room_id)):
-                yield self.store.purge_history(room_id, token, delete_local_events)
+                yield self.storage.purge_events.purge_history(
+                    room_id, token, delete_local_events
+                )
             logger.info("[purge] complete")
             self._purges_by_id[purge_id].status = PurgeStatus.STATUS_COMPLETE
         except Exception:
@@ -158,7 +281,7 @@ class PaginationHandler(object):
         """Purge the given room from the database"""
         with (await self.pagination_lock.write(room_id)):
             # check we know about the room
-            await self.store.get_room_version(room_id)
+            await self.store.get_room_version_id(room_id)
 
             # first check that we have no users in this room
             joined = await defer.maybeDeferred(
@@ -168,10 +291,9 @@ class PaginationHandler(object):
             if joined:
                 raise SynapseError(400, "Users are still joined to this room")
 
-            await self.store.purge_room(room_id)
+            await self.storage.purge_events.purge_room(room_id)
 
-    @defer.inlineCallbacks
-    def get_messages(
+    async def get_messages(
         self,
         requester,
         room_id=None,
@@ -197,7 +319,7 @@ class PaginationHandler(object):
             room_token = pagin_config.from_token.room_key
         else:
             pagin_config.from_token = (
-                yield self.hs.get_event_sources().get_current_token_for_pagination()
+                await self.hs.get_event_sources().get_current_token_for_pagination()
             )
             room_token = pagin_config.from_token.room_key
 
@@ -209,9 +331,12 @@ class PaginationHandler(object):
 
         source_config = pagin_config.get_source_config("room")
 
-        with (yield self.pagination_lock.read(room_id)):
-            membership, member_event_id = yield self.auth.check_in_room_or_world_readable(
-                room_id, user_id
+        with (await self.pagination_lock.read(room_id)):
+            (
+                membership,
+                member_event_id,
+            ) = await self.auth.check_user_in_room_or_world_readable(
+                room_id, user_id, allow_departed_users=True
             )
 
             if source_config.direction == "b":
@@ -220,7 +345,7 @@ class PaginationHandler(object):
                 if room_token.topological:
                     max_topo = room_token.topological
                 else:
-                    max_topo = yield self.store.get_max_topological_token(
+                    max_topo = await self.store.get_max_topological_token(
                         room_id, room_token.stream
                     )
 
@@ -228,18 +353,18 @@ class PaginationHandler(object):
                     # If they have left the room then clamp the token to be before
                     # they left the room, to save the effort of loading from the
                     # database.
-                    leave_token = yield self.store.get_topological_token_for_event(
+                    leave_token = await self.store.get_topological_token_for_event(
                         member_event_id
                     )
                     leave_token = RoomStreamToken.parse(leave_token)
                     if leave_token.topological < max_topo:
                         source_config.from_key = str(leave_token)
 
-                yield self.hs.get_handlers().federation_handler.maybe_backfill(
+                await self.hs.get_handlers().federation_handler.maybe_backfill(
                     room_id, max_topo
                 )
 
-            events, next_key = yield self.store.paginate_room_events(
+            events, next_key = await self.store.paginate_room_events(
                 room_id=room_id,
                 from_key=source_config.from_key,
                 to_key=source_config.to_key,
@@ -254,8 +379,8 @@ class PaginationHandler(object):
             if event_filter:
                 events = event_filter.filter(events)
 
-            events = yield filter_events_for_client(
-                self.store, user_id, events, is_peeking=(member_event_id is None)
+            events = await filter_events_for_client(
+                self.storage, user_id, events, is_peeking=(member_event_id is None)
             )
 
         if not events:
@@ -274,19 +399,19 @@ class PaginationHandler(object):
                 (EventTypes.Member, event.sender) for event in events
             )
 
-            state_ids = yield self.store.get_state_ids_for_event(
+            state_ids = await self.state_store.get_state_ids_for_event(
                 events[0].event_id, state_filter=state_filter
             )
 
             if state_ids:
-                state = yield self.store.get_events(list(state_ids.values()))
+                state = await self.store.get_events(list(state_ids.values()))
                 state = state.values()
 
         time_now = self.clock.time_msec()
 
         chunk = {
             "chunk": (
-                yield self._event_serializer.serialize_events(
+                await self._event_serializer.serialize_events(
                     events, time_now, as_client_event=as_client_event
                 )
             ),
@@ -295,10 +420,8 @@ class PaginationHandler(object):
         }
 
         if state:
-            chunk["state"] = (
-                yield self._event_serializer.serialize_events(
-                    state, time_now, as_client_event=as_client_event
-                )
+            chunk["state"] = await self._event_serializer.serialize_events(
+                state, time_now, as_client_event=as_client_event
             )
 
         return chunk
diff --git a/synapse/handlers/password_policy.py b/synapse/handlers/password_policy.py
new file mode 100644
index 0000000000..d06b110269
--- /dev/null
+++ b/synapse/handlers/password_policy.py
@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+import re
+
+from synapse.api.errors import Codes, PasswordRefusedError
+
+logger = logging.getLogger(__name__)
+
+
+class PasswordPolicyHandler(object):
+    def __init__(self, hs):
+        self.policy = hs.config.password_policy
+        self.enabled = hs.config.password_policy_enabled
+
+        # Regexps for the spec'd policy parameters.
+        self.regexp_digit = re.compile("[0-9]")
+        self.regexp_symbol = re.compile("[^a-zA-Z0-9]")
+        self.regexp_uppercase = re.compile("[A-Z]")
+        self.regexp_lowercase = re.compile("[a-z]")
+
+    def validate_password(self, password):
+        """Checks whether a given password complies with the server's policy.
+
+        Args:
+            password (str): The password to check against the server's policy.
+
+        Raises:
+            PasswordRefusedError: The password doesn't comply with the server's policy.
+        """
+
+        if not self.enabled:
+            return
+
+        minimum_accepted_length = self.policy.get("minimum_length", 0)
+        if len(password) < minimum_accepted_length:
+            raise PasswordRefusedError(
+                msg=(
+                    "The password must be at least %d characters long"
+                    % minimum_accepted_length
+                ),
+                errcode=Codes.PASSWORD_TOO_SHORT,
+            )
+
+        if (
+            self.policy.get("require_digit", False)
+            and self.regexp_digit.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one digit",
+                errcode=Codes.PASSWORD_NO_DIGIT,
+            )
+
+        if (
+            self.policy.get("require_symbol", False)
+            and self.regexp_symbol.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one symbol",
+                errcode=Codes.PASSWORD_NO_SYMBOL,
+            )
+
+        if (
+            self.policy.get("require_uppercase", False)
+            and self.regexp_uppercase.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one uppercase letter",
+                errcode=Codes.PASSWORD_NO_UPPERCASE,
+            )
+
+        if (
+            self.policy.get("require_lowercase", False)
+            and self.regexp_lowercase.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one lowercase letter",
+                errcode=Codes.PASSWORD_NO_LOWERCASE,
+            )
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 053cf66b28..3594f3b00f 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2020 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -21,13 +22,15 @@ The methods that define policy are:
     - PresenceHandler._handle_timeouts
     - should_notify
 """
-
+import abc
 import logging
 from contextlib import contextmanager
+from typing import Dict, Iterable, List, Set
 
 from six import iteritems, itervalues
 
 from prometheus_client import Counter
+from typing_extensions import ContextManager
 
 from twisted.internet import defer
 
@@ -39,12 +42,16 @@ from synapse.logging.utils import log_function
 from synapse.metrics import LaterGauge
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.presence import UserPresenceState
-from synapse.types import UserID, get_domain_from_id
+from synapse.types import JsonDict, UserID, get_domain_from_id
 from synapse.util.async_helpers import Linearizer
-from synapse.util.caches.descriptors import cachedInlineCallbacks
+from synapse.util.caches.descriptors import cached
 from synapse.util.metrics import Measure
 from synapse.util.wheel_timer import WheelTimer
 
+MYPY = False
+if MYPY:
+    import synapse.server
+
 logger = logging.getLogger(__name__)
 
 
@@ -93,35 +100,122 @@ EXTERNAL_PROCESS_EXPIRY = 5 * 60 * 1000
 assert LAST_ACTIVE_GRANULARITY < IDLE_TIMER
 
 
-class PresenceHandler(object):
-    def __init__(self, hs):
-        """
+class BasePresenceHandler(abc.ABC):
+    """Parts of the PresenceHandler that are shared between workers and master"""
+
+    def __init__(self, hs: "synapse.server.HomeServer"):
+        self.clock = hs.get_clock()
+        self.store = hs.get_datastore()
+
+        active_presence = self.store.take_presence_startup_info()
+        self.user_to_current_state = {state.user_id: state for state in active_presence}
+
+    @abc.abstractmethod
+    async def user_syncing(
+        self, user_id: str, affect_presence: bool
+    ) -> ContextManager[None]:
+        """Returns a context manager that should surround any stream requests
+        from the user.
+
+        This allows us to keep track of who is currently streaming and who isn't
+        without having to have timers outside of this module to avoid flickering
+        when users disconnect/reconnect.
 
         Args:
-            hs (synapse.server.HomeServer):
+            user_id: the user that is starting a sync
+            affect_presence: If false this function will be a no-op.
+                Useful for streams that are not associated with an actual
+                client that is being used by a user.
+        """
+
+    @abc.abstractmethod
+    def get_currently_syncing_users_for_replication(self) -> Iterable[str]:
+        """Get an iterable of syncing users on this worker, to send to the presence handler
+
+        This is called when a replication connection is established. It should return
+        a list of user ids, which are then sent as USER_SYNC commands to inform the
+        process handling presence about those users.
+
+        Returns:
+            An iterable of user_id strings.
         """
+
+    async def get_state(self, target_user: UserID) -> UserPresenceState:
+        results = await self.get_states([target_user.to_string()])
+        return results[0]
+
+    async def get_states(
+        self, target_user_ids: Iterable[str]
+    ) -> List[UserPresenceState]:
+        """Get the presence state for users."""
+
+        updates_d = await self.current_state_for_users(target_user_ids)
+        updates = list(updates_d.values())
+
+        for user_id in set(target_user_ids) - {u.user_id for u in updates}:
+            updates.append(UserPresenceState.default(user_id))
+
+        return updates
+
+    async def current_state_for_users(
+        self, user_ids: Iterable[str]
+    ) -> Dict[str, UserPresenceState]:
+        """Get the current presence state for multiple users.
+
+        Returns:
+            dict: `user_id` -> `UserPresenceState`
+        """
+        states = {
+            user_id: self.user_to_current_state.get(user_id, None)
+            for user_id in user_ids
+        }
+
+        missing = [user_id for user_id, state in iteritems(states) if not state]
+        if missing:
+            # There are things not in our in memory cache. Lets pull them out of
+            # the database.
+            res = await self.store.get_presence_for_users(missing)
+            states.update(res)
+
+            missing = [user_id for user_id, state in iteritems(states) if not state]
+            if missing:
+                new = {
+                    user_id: UserPresenceState.default(user_id) for user_id in missing
+                }
+                states.update(new)
+                self.user_to_current_state.update(new)
+
+        return states
+
+    @abc.abstractmethod
+    async def set_state(
+        self, target_user: UserID, state: JsonDict, ignore_status_msg: bool = False
+    ) -> None:
+        """Set the presence state of the user. """
+
+    @abc.abstractmethod
+    async def bump_presence_active_time(self, user: UserID):
+        """We've seen the user do something that indicates they're interacting
+        with the app.
+        """
+
+
+class PresenceHandler(BasePresenceHandler):
+    def __init__(self, hs: "synapse.server.HomeServer"):
+        super().__init__(hs)
         self.hs = hs
-        self.is_mine = hs.is_mine
         self.is_mine_id = hs.is_mine_id
         self.server_name = hs.hostname
-        self.clock = hs.get_clock()
-        self.store = hs.get_datastore()
         self.wheel_timer = WheelTimer()
         self.notifier = hs.get_notifier()
         self.federation = hs.get_federation_sender()
         self.state = hs.get_state_handler()
+        self._presence_enabled = hs.config.use_presence
 
         federation_registry = hs.get_federation_registry()
 
         federation_registry.register_edu_handler("m.presence", self.incoming_presence)
 
-        active_presence = self.store.take_presence_startup_info()
-
-        # A dictionary of the current state of users. This is prefilled with
-        # non-offline presence from the DB. We should fetch from the DB if
-        # we can't find a users presence in here.
-        self.user_to_current_state = {state.user_id: state for state in active_presence}
-
         LaterGauge(
             "synapse_handlers_presence_user_to_current_state_size",
             "",
@@ -130,7 +224,7 @@ class PresenceHandler(object):
         )
 
         now = self.clock.time_msec()
-        for state in active_presence:
+        for state in self.user_to_current_state.values():
             self.wheel_timer.insert(
                 now=now, obj=state.user_id, then=state.last_active_ts + IDLE_TIMER
             )
@@ -154,7 +248,7 @@ class PresenceHandler(object):
 
         # Set of users who have presence in the `user_to_current_state` that
         # have not yet been persisted
-        self.unpersisted_users_changes = set()
+        self.unpersisted_users_changes = set()  # type: Set[str]
 
         hs.get_reactor().addSystemEventTrigger(
             "before",
@@ -164,12 +258,11 @@ class PresenceHandler(object):
             self._on_shutdown,
         )
 
-        self.serial_to_user = {}
         self._next_serial = 1
 
         # Keeps track of the number of *ongoing* syncs on this process. While
         # this is non zero a user will never go offline.
-        self.user_to_num_current_syncs = {}
+        self.user_to_num_current_syncs = {}  # type: Dict[str, int]
 
         # Keeps track of the number of *ongoing* syncs on other processes.
         # While any sync is ongoing on another process the user will never
@@ -179,8 +272,9 @@ class PresenceHandler(object):
         # we assume that all the sync requests on that process have stopped.
         # Stored as a dict from process_id to set of user_id, and a dict of
         # process_id to millisecond timestamp last updated.
-        self.external_process_to_current_syncs = {}
-        self.external_process_last_updated_ms = {}
+        self.external_process_to_current_syncs = {}  # type: Dict[int, Set[str]]
+        self.external_process_last_updated_ms = {}  # type: Dict[int, int]
+
         self.external_sync_linearizer = Linearizer(name="external_sync_linearizer")
 
         # Start a LoopingCall in 30s that fires every 5s.
@@ -216,8 +310,7 @@ class PresenceHandler(object):
         self._event_pos = self.store.get_current_events_token()
         self._event_processing = False
 
-    @defer.inlineCallbacks
-    def _on_shutdown(self):
+    async def _on_shutdown(self):
         """Gets called when shutting down. This lets us persist any updates that
         we haven't yet persisted, e.g. updates that only changes some internal
         timers. This allows changes to persist across startup without having to
@@ -228,7 +321,7 @@ class PresenceHandler(object):
         is some spurious presence changes that will self-correct.
         """
         # If the DB pool has already terminated, don't try updating
-        if not self.hs.get_db_pool().running:
+        if not self.store.db.is_running():
             return
 
         logger.info(
@@ -238,7 +331,7 @@ class PresenceHandler(object):
 
         if self.unpersisted_users_changes:
 
-            yield self.store.update_presence(
+            await self.store.update_presence(
                 [
                     self.user_to_current_state[user_id]
                     for user_id in self.unpersisted_users_changes
@@ -246,8 +339,7 @@ class PresenceHandler(object):
             )
         logger.info("Finished _on_shutdown")
 
-    @defer.inlineCallbacks
-    def _persist_unpersisted_changes(self):
+    async def _persist_unpersisted_changes(self):
         """We periodically persist the unpersisted changes, as otherwise they
         may stack up and slow down shutdown times.
         """
@@ -256,12 +348,11 @@ class PresenceHandler(object):
 
         if unpersisted:
             logger.info("Persisting %d unpersisted presence updates", len(unpersisted))
-            yield self.store.update_presence(
+            await self.store.update_presence(
                 [self.user_to_current_state[user_id] for user_id in unpersisted]
             )
 
-    @defer.inlineCallbacks
-    def _update_states(self, new_states):
+    async def _update_states(self, new_states):
         """Updates presence of users. Sets the appropriate timeouts. Pokes
         the notifier and federation if and only if the changed presence state
         should be sent to clients/servers.
@@ -270,7 +361,7 @@ class PresenceHandler(object):
 
         with Measure(self.clock, "presence_update_states"):
 
-            # NOTE: We purposefully don't yield between now and when we've
+            # NOTE: We purposefully don't await between now and when we've
             # calculated what we want to do with the new states, to avoid races.
 
             to_notify = {}  # Changes we want to notify everyone about
@@ -314,9 +405,9 @@ class PresenceHandler(object):
 
             if to_notify:
                 notified_presence_counter.inc(len(to_notify))
-                yield self._persist_and_notify(list(to_notify.values()))
+                await self._persist_and_notify(list(to_notify.values()))
 
-            self.unpersisted_users_changes |= set(s.user_id for s in new_states)
+            self.unpersisted_users_changes |= {s.user_id for s in new_states}
             self.unpersisted_users_changes -= set(to_notify.keys())
 
             to_federation_ping = {
@@ -329,7 +420,7 @@ class PresenceHandler(object):
 
                 self._push_to_remotes(to_federation_ping.values())
 
-    def _handle_timeouts(self):
+    async def _handle_timeouts(self):
         """Checks the presence of users that have timed out and updates as
         appropriate.
         """
@@ -349,10 +440,13 @@ class PresenceHandler(object):
             if now - last_update > EXTERNAL_PROCESS_EXPIRY
         ]
         for process_id in expired_process_ids:
+            # For each expired process drop tracking info and check the users
+            # that were syncing on that process to see if they need to be timed
+            # out.
             users_to_check.update(
-                self.external_process_last_updated_ms.pop(process_id, ())
+                self.external_process_to_current_syncs.pop(process_id, ())
             )
-            self.external_process_last_update.pop(process_id)
+            self.external_process_last_updated_ms.pop(process_id)
 
         states = [
             self.user_to_current_state.get(user_id, UserPresenceState.default(user_id))
@@ -361,17 +455,24 @@ class PresenceHandler(object):
 
         timers_fired_counter.inc(len(states))
 
+        syncing_user_ids = {
+            user_id
+            for user_id, count in self.user_to_num_current_syncs.items()
+            if count
+        }
+        for user_ids in self.external_process_to_current_syncs.values():
+            syncing_user_ids.update(user_ids)
+
         changes = handle_timeouts(
             states,
             is_mine_fn=self.is_mine_id,
-            syncing_user_ids=self.get_currently_syncing_users(),
+            syncing_user_ids=syncing_user_ids,
             now=now,
         )
 
-        return self._update_states(changes)
+        return await self._update_states(changes)
 
-    @defer.inlineCallbacks
-    def bump_presence_active_time(self, user):
+    async def bump_presence_active_time(self, user):
         """We've seen the user do something that indicates they're interacting
         with the app.
         """
@@ -383,16 +484,17 @@ class PresenceHandler(object):
 
         bump_active_time_counter.inc()
 
-        prev_state = yield self.current_state_for_user(user_id)
+        prev_state = await self.current_state_for_user(user_id)
 
         new_fields = {"last_active_ts": self.clock.time_msec()}
         if prev_state.state == PresenceState.UNAVAILABLE:
             new_fields["state"] = PresenceState.ONLINE
 
-        yield self._update_states([prev_state.copy_and_replace(**new_fields)])
+        await self._update_states([prev_state.copy_and_replace(**new_fields)])
 
-    @defer.inlineCallbacks
-    def user_syncing(self, user_id, affect_presence=True):
+    async def user_syncing(
+        self, user_id: str, affect_presence: bool = True
+    ) -> ContextManager[None]:
         """Returns a context manager that should surround any stream requests
         from the user.
 
@@ -415,11 +517,11 @@ class PresenceHandler(object):
             curr_sync = self.user_to_num_current_syncs.get(user_id, 0)
             self.user_to_num_current_syncs[user_id] = curr_sync + 1
 
-            prev_state = yield self.current_state_for_user(user_id)
+            prev_state = await self.current_state_for_user(user_id)
             if prev_state.state == PresenceState.OFFLINE:
                 # If they're currently offline then bring them online, otherwise
                 # just update the last sync times.
-                yield self._update_states(
+                await self._update_states(
                     [
                         prev_state.copy_and_replace(
                             state=PresenceState.ONLINE,
@@ -429,7 +531,7 @@ class PresenceHandler(object):
                     ]
                 )
             else:
-                yield self._update_states(
+                await self._update_states(
                     [
                         prev_state.copy_and_replace(
                             last_user_sync_ts=self.clock.time_msec()
@@ -437,13 +539,12 @@ class PresenceHandler(object):
                     ]
                 )
 
-        @defer.inlineCallbacks
-        def _end():
+        async def _end():
             try:
                 self.user_to_num_current_syncs[user_id] -= 1
 
-                prev_state = yield self.current_state_for_user(user_id)
-                yield self._update_states(
+                prev_state = await self.current_state_for_user(user_id)
+                await self._update_states(
                     [
                         prev_state.copy_and_replace(
                             last_user_sync_ts=self.clock.time_msec()
@@ -463,25 +564,11 @@ class PresenceHandler(object):
 
         return _user_syncing()
 
-    def get_currently_syncing_users(self):
-        """Get the set of user ids that are currently syncing on this HS.
-        Returns:
-            set(str): A set of user_id strings.
-        """
-        if self.hs.config.use_presence:
-            syncing_user_ids = {
-                user_id
-                for user_id, count in self.user_to_num_current_syncs.items()
-                if count
-            }
-            for user_ids in self.external_process_to_current_syncs.values():
-                syncing_user_ids.update(user_ids)
-            return syncing_user_ids
-        else:
-            return set()
+    def get_currently_syncing_users_for_replication(self) -> Iterable[str]:
+        # since we are the process handling presence, there is nothing to do here.
+        return []
 
-    @defer.inlineCallbacks
-    def update_external_syncs_row(
+    async def update_external_syncs_row(
         self, process_id, user_id, is_syncing, sync_time_msec
     ):
         """Update the syncing users for an external process as a delta.
@@ -494,8 +581,8 @@ class PresenceHandler(object):
             is_syncing (bool): Whether or not the user is now syncing
             sync_time_msec(int): Time in ms when the user was last syncing
         """
-        with (yield self.external_sync_linearizer.queue(process_id)):
-            prev_state = yield self.current_state_for_user(user_id)
+        with (await self.external_sync_linearizer.queue(process_id)):
+            prev_state = await self.current_state_for_user(user_id)
 
             process_presence = self.external_process_to_current_syncs.setdefault(
                 process_id, set()
@@ -525,25 +612,24 @@ class PresenceHandler(object):
                 process_presence.discard(user_id)
 
             if updates:
-                yield self._update_states(updates)
+                await self._update_states(updates)
 
             self.external_process_last_updated_ms[process_id] = self.clock.time_msec()
 
-    @defer.inlineCallbacks
-    def update_external_syncs_clear(self, process_id):
+    async def update_external_syncs_clear(self, process_id):
         """Marks all users that had been marked as syncing by a given process
         as offline.
 
         Used when the process has stopped/disappeared.
         """
-        with (yield self.external_sync_linearizer.queue(process_id)):
+        with (await self.external_sync_linearizer.queue(process_id)):
             process_presence = self.external_process_to_current_syncs.pop(
                 process_id, set()
             )
-            prev_states = yield self.current_state_for_users(process_presence)
+            prev_states = await self.current_state_for_users(process_presence)
             time_now_ms = self.clock.time_msec()
 
-            yield self._update_states(
+            await self._update_states(
                 [
                     prev_state.copy_and_replace(last_user_sync_ts=time_now_ms)
                     for prev_state in itervalues(prev_states)
@@ -551,50 +637,19 @@ class PresenceHandler(object):
             )
             self.external_process_last_updated_ms.pop(process_id, None)
 
-    @defer.inlineCallbacks
-    def current_state_for_user(self, user_id):
+    async def current_state_for_user(self, user_id):
         """Get the current presence state for a user.
         """
-        res = yield self.current_state_for_users([user_id])
+        res = await self.current_state_for_users([user_id])
         return res[user_id]
 
-    @defer.inlineCallbacks
-    def current_state_for_users(self, user_ids):
-        """Get the current presence state for multiple users.
-
-        Returns:
-            dict: `user_id` -> `UserPresenceState`
-        """
-        states = {
-            user_id: self.user_to_current_state.get(user_id, None)
-            for user_id in user_ids
-        }
-
-        missing = [user_id for user_id, state in iteritems(states) if not state]
-        if missing:
-            # There are things not in our in memory cache. Lets pull them out of
-            # the database.
-            res = yield self.store.get_presence_for_users(missing)
-            states.update(res)
-
-            missing = [user_id for user_id, state in iteritems(states) if not state]
-            if missing:
-                new = {
-                    user_id: UserPresenceState.default(user_id) for user_id in missing
-                }
-                states.update(new)
-                self.user_to_current_state.update(new)
-
-        return states
-
-    @defer.inlineCallbacks
-    def _persist_and_notify(self, states):
+    async def _persist_and_notify(self, states):
         """Persist states in the database, poke the notifier and send to
         interested remote servers
         """
-        stream_id, max_token = yield self.store.update_presence(states)
+        stream_id, max_token = await self.store.update_presence(states)
 
-        parties = yield get_interested_parties(self.store, states)
+        parties = await get_interested_parties(self.store, states)
         room_ids_to_states, users_to_states = parties
 
         self.notifier.on_new_event(
@@ -606,9 +661,8 @@ class PresenceHandler(object):
 
         self._push_to_remotes(states)
 
-    @defer.inlineCallbacks
-    def notify_for_states(self, state, stream_id):
-        parties = yield get_interested_parties(self.store, [state])
+    async def notify_for_states(self, state, stream_id):
+        parties = await get_interested_parties(self.store, [state])
         room_ids_to_states, users_to_states = parties
 
         self.notifier.on_new_event(
@@ -626,17 +680,17 @@ class PresenceHandler(object):
         """
         self.federation.send_presence(states)
 
-    @defer.inlineCallbacks
-    def incoming_presence(self, origin, content):
+    async def incoming_presence(self, origin, content):
         """Called when we receive a `m.presence` EDU from a remote server.
         """
+        if not self._presence_enabled:
+            return
+
         now = self.clock.time_msec()
         updates = []
         for push in content.get("push", []):
             # A "push" contains a list of presence that we are probably interested
             # in.
-            # TODO: Actually check if we're interested, rather than blindly
-            # accepting presence updates.
             user_id = push.get("user_id", None)
             if not user_id:
                 logger.info(
@@ -670,51 +724,14 @@ class PresenceHandler(object):
             new_fields["status_msg"] = push.get("status_msg", None)
             new_fields["currently_active"] = push.get("currently_active", False)
 
-            prev_state = yield self.current_state_for_user(user_id)
+            prev_state = await self.current_state_for_user(user_id)
             updates.append(prev_state.copy_and_replace(**new_fields))
 
         if updates:
             federation_presence_counter.inc(len(updates))
-            yield self._update_states(updates)
-
-    @defer.inlineCallbacks
-    def get_state(self, target_user, as_event=False):
-        results = yield self.get_states([target_user.to_string()], as_event=as_event)
-
-        return results[0]
-
-    @defer.inlineCallbacks
-    def get_states(self, target_user_ids, as_event=False):
-        """Get the presence state for users.
+            await self._update_states(updates)
 
-        Args:
-            target_user_ids (list)
-            as_event (bool): Whether to format it as a client event or not.
-
-        Returns:
-            list
-        """
-
-        updates = yield self.current_state_for_users(target_user_ids)
-        updates = list(updates.values())
-
-        for user_id in set(target_user_ids) - set(u.user_id for u in updates):
-            updates.append(UserPresenceState.default(user_id))
-
-        now = self.clock.time_msec()
-        if as_event:
-            return [
-                {
-                    "type": "m.presence",
-                    "content": format_user_presence_state(state, now),
-                }
-                for state in updates
-            ]
-        else:
-            return updates
-
-    @defer.inlineCallbacks
-    def set_state(self, target_user, state, ignore_status_msg=False):
+    async def set_state(self, target_user, state, ignore_status_msg=False):
         """Set the presence state of the user.
         """
         status_msg = state.get("status_msg", None)
@@ -730,7 +747,7 @@ class PresenceHandler(object):
 
         user_id = target_user.to_string()
 
-        prev_state = yield self.current_state_for_user(user_id)
+        prev_state = await self.current_state_for_user(user_id)
 
         new_fields = {"state": presence}
 
@@ -741,16 +758,15 @@ class PresenceHandler(object):
         if presence == PresenceState.ONLINE:
             new_fields["last_active_ts"] = self.clock.time_msec()
 
-        yield self._update_states([prev_state.copy_and_replace(**new_fields)])
+        await self._update_states([prev_state.copy_and_replace(**new_fields)])
 
-    @defer.inlineCallbacks
-    def is_visible(self, observed_user, observer_user):
+    async def is_visible(self, observed_user, observer_user):
         """Returns whether a user can see another user's presence.
         """
-        observer_room_ids = yield self.store.get_rooms_for_user(
+        observer_room_ids = await self.store.get_rooms_for_user(
             observer_user.to_string()
         )
-        observed_room_ids = yield self.store.get_rooms_for_user(
+        observed_room_ids = await self.store.get_rooms_for_user(
             observed_user.to_string()
         )
 
@@ -759,8 +775,7 @@ class PresenceHandler(object):
 
         return False
 
-    @defer.inlineCallbacks
-    def get_all_presence_updates(self, last_id, current_id):
+    async def get_all_presence_updates(self, last_id, current_id, limit):
         """
         Gets a list of presence update rows from between the given stream ids.
         Each row has:
@@ -775,7 +790,7 @@ class PresenceHandler(object):
         """
         # TODO(markjh): replicate the unpersisted changes.
         # This could use the in-memory stores for recent changes.
-        rows = yield self.store.get_all_presence_updates(last_id, current_id)
+        rows = await self.store.get_all_presence_updates(last_id, current_id, limit)
         return rows
 
     def notify_new_event(self):
@@ -786,38 +801,43 @@ class PresenceHandler(object):
         if self._event_processing:
             return
 
-        @defer.inlineCallbacks
-        def _process_presence():
+        async def _process_presence():
             assert not self._event_processing
 
             self._event_processing = True
             try:
-                yield self._unsafe_process()
+                await self._unsafe_process()
             finally:
                 self._event_processing = False
 
         run_as_background_process("presence.notify_new_event", _process_presence)
 
-    @defer.inlineCallbacks
-    def _unsafe_process(self):
+    async def _unsafe_process(self):
         # Loop round handling deltas until we're up to date
         while True:
             with Measure(self.clock, "presence_delta"):
-                deltas = yield self.store.get_current_state_deltas(self._event_pos)
-                if not deltas:
+                room_max_stream_ordering = self.store.get_room_max_stream_ordering()
+                if self._event_pos == room_max_stream_ordering:
                     return
 
-                yield self._handle_state_delta(deltas)
+                logger.debug(
+                    "Processing presence stats %s->%s",
+                    self._event_pos,
+                    room_max_stream_ordering,
+                )
+                max_pos, deltas = await self.store.get_current_state_deltas(
+                    self._event_pos, room_max_stream_ordering
+                )
+                await self._handle_state_delta(deltas)
 
-                self._event_pos = deltas[-1]["stream_id"]
+                self._event_pos = max_pos
 
                 # Expose current event processing position to prometheus
                 synapse.metrics.event_processing_positions.labels("presence").set(
-                    self._event_pos
+                    max_pos
                 )
 
-    @defer.inlineCallbacks
-    def _handle_state_delta(self, deltas):
+    async def _handle_state_delta(self, deltas):
         """Process current state deltas to find new joins that need to be
         handled.
         """
@@ -838,13 +858,13 @@ class PresenceHandler(object):
                 # joins.
                 continue
 
-            event = yield self.store.get_event(event_id, allow_none=True)
+            event = await self.store.get_event(event_id, allow_none=True)
             if not event or event.content.get("membership") != Membership.JOIN:
                 # We only care about joins
                 continue
 
             if prev_event_id:
-                prev_event = yield self.store.get_event(prev_event_id, allow_none=True)
+                prev_event = await self.store.get_event(prev_event_id, allow_none=True)
                 if (
                     prev_event
                     and prev_event.content.get("membership") == Membership.JOIN
@@ -852,10 +872,9 @@ class PresenceHandler(object):
                     # Ignore changes to join events.
                     continue
 
-            yield self._on_user_joined_room(room_id, state_key)
+            await self._on_user_joined_room(room_id, state_key)
 
-    @defer.inlineCallbacks
-    def _on_user_joined_room(self, room_id, user_id):
+    async def _on_user_joined_room(self, room_id, user_id):
         """Called when we detect a user joining the room via the current state
         delta stream.
 
@@ -874,11 +893,11 @@ class PresenceHandler(object):
             # TODO: We should be able to filter the hosts down to those that
             # haven't previously seen the user
 
-            state = yield self.current_state_for_user(user_id)
-            hosts = yield self.state.get_current_hosts_in_room(room_id)
+            state = await self.current_state_for_user(user_id)
+            hosts = await self.state.get_current_hosts_in_room(room_id)
 
             # Filter out ourselves.
-            hosts = set(host for host in hosts if host != self.server_name)
+            hosts = {host for host in hosts if host != self.server_name}
 
             self.federation.send_presence_to_destinations(
                 states=[state], destinations=hosts
@@ -895,10 +914,10 @@ class PresenceHandler(object):
             # TODO: Check that this is actually a new server joining the
             # room.
 
-            user_ids = yield self.state.get_current_users_in_room(room_id)
+            user_ids = await self.state.get_current_users_in_room(room_id)
             user_ids = list(filter(self.is_mine_id, user_ids))
 
-            states = yield self.current_state_for_users(user_ids)
+            states_d = await self.current_state_for_users(user_ids)
 
             # Filter out old presence, i.e. offline presence states where
             # the user hasn't been active for a week. We can change this
@@ -908,7 +927,7 @@ class PresenceHandler(object):
             now = self.clock.time_msec()
             states = [
                 state
-                for state in states.values()
+                for state in states_d.values()
                 if state.state != PresenceState.OFFLINE
                 or now - state.last_active_ts < 7 * 24 * 60 * 60 * 1000
                 or state.status_msg is not None
@@ -988,9 +1007,8 @@ class PresenceEventSource(object):
         self.store = hs.get_datastore()
         self.state = hs.get_state_handler()
 
-    @defer.inlineCallbacks
     @log_function
-    def get_new_events(
+    async def get_new_events(
         self,
         user,
         from_key,
@@ -1037,7 +1055,7 @@ class PresenceEventSource(object):
             presence = self.get_presence_handler()
             stream_change_cache = self.store.presence_stream_cache
 
-            users_interested_in = yield self._get_interested_in(user, explicit_room_id)
+            users_interested_in = await self._get_interested_in(user, explicit_room_id)
 
             user_ids_changed = set()
             changed = None
@@ -1063,7 +1081,7 @@ class PresenceEventSource(object):
                 else:
                     user_ids_changed = users_interested_in
 
-            updates = yield presence.current_state_for_users(user_ids_changed)
+            updates = await presence.current_state_for_users(user_ids_changed)
 
         if include_offline:
             return (list(updates.values()), max_token)
@@ -1076,11 +1094,11 @@ class PresenceEventSource(object):
     def get_current_key(self):
         return self.store.get_current_presence_token()
 
-    def get_pagination_rows(self, user, pagination_config, key):
-        return self.get_new_events(user, from_key=None, include_offline=False)
+    async def get_pagination_rows(self, user, pagination_config, key):
+        return await self.get_new_events(user, from_key=None, include_offline=False)
 
-    @cachedInlineCallbacks(num_args=2, cache_context=True)
-    def _get_interested_in(self, user, explicit_room_id, cache_context):
+    @cached(num_args=2, cache_context=True)
+    async def _get_interested_in(self, user, explicit_room_id, cache_context):
         """Returns the set of users that the given user should see presence
         updates for
         """
@@ -1088,13 +1106,13 @@ class PresenceEventSource(object):
         users_interested_in = set()
         users_interested_in.add(user_id)  # So that we receive our own presence
 
-        users_who_share_room = yield self.store.get_users_who_share_room_with_user(
+        users_who_share_room = await self.store.get_users_who_share_room_with_user(
             user_id, on_invalidate=cache_context.invalidate
         )
         users_interested_in.update(users_who_share_room)
 
         if explicit_room_id:
-            user_ids = yield self.store.get_users_in_room(
+            user_ids = await self.store.get_users_in_room(
                 explicit_room_id, on_invalidate=cache_context.invalidate
             )
             users_interested_in.update(user_ids)
@@ -1269,8 +1287,8 @@ def get_interested_parties(store, states):
         2-tuple: `(room_ids_to_states, users_to_states)`,
         with each item being a dict of `entity_name` -> `[UserPresenceState]`
     """
-    room_ids_to_states = {}
-    users_to_states = {}
+    room_ids_to_states = {}  # type: Dict[str, List[UserPresenceState]]
+    users_to_states = {}  # type: Dict[str, List[UserPresenceState]]
     for state in states:
         room_ids = yield store.get_rooms_for_user(state.user_id)
         for room_id in room_ids:
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 8690f69d45..302efc1b9a 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -28,7 +28,7 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.types import UserID, get_domain_from_id
+from synapse.types import UserID, create_requester, get_domain_from_id
 
 from ._base import BaseHandler
 
@@ -141,8 +141,9 @@ class BaseProfileHandler(BaseHandler):
 
             return result["displayname"]
 
-    @defer.inlineCallbacks
-    def set_displayname(self, target_user, requester, new_displayname, by_admin=False):
+    async def set_displayname(
+        self, target_user, requester, new_displayname, by_admin=False
+    ):
         """Set the displayname of a user
 
         Args:
@@ -152,11 +153,20 @@ class BaseProfileHandler(BaseHandler):
             by_admin (bool): Whether this change was made by an administrator.
         """
         if not self.hs.is_mine(target_user):
-            raise SynapseError(400, "User is not hosted on this Home Server")
+            raise SynapseError(400, "User is not hosted on this homeserver")
 
         if not by_admin and target_user != requester.user:
             raise AuthError(400, "Cannot set another user's displayname")
 
+        if not by_admin and not self.hs.config.enable_set_displayname:
+            profile = await self.store.get_profileinfo(target_user.localpart)
+            if profile.display_name:
+                raise SynapseError(
+                    400,
+                    "Changing display name is disabled on this server",
+                    Codes.FORBIDDEN,
+                )
+
         if len(new_displayname) > MAX_DISPLAYNAME_LEN:
             raise SynapseError(
                 400, "Displayname is too long (max %i)" % (MAX_DISPLAYNAME_LEN,)
@@ -165,15 +175,21 @@ class BaseProfileHandler(BaseHandler):
         if new_displayname == "":
             new_displayname = None
 
-        yield self.store.set_profile_displayname(target_user.localpart, new_displayname)
+        # If the admin changes the display name of a user, the requesting user cannot send
+        # the join event to update the displayname in the rooms.
+        # This must be done by the target user himself.
+        if by_admin:
+            requester = create_requester(target_user)
+
+        await self.store.set_profile_displayname(target_user.localpart, new_displayname)
 
         if self.hs.config.user_directory_search_all_users:
-            profile = yield self.store.get_profileinfo(target_user.localpart)
-            yield self.user_directory_handler.handle_local_profile_change(
+            profile = await self.store.get_profileinfo(target_user.localpart)
+            await self.user_directory_handler.handle_local_profile_change(
                 target_user.to_string(), profile
             )
 
-        yield self._update_join_states(requester, target_user)
+        await self._update_join_states(requester, target_user)
 
     @defer.inlineCallbacks
     def get_avatar_url(self, target_user):
@@ -202,36 +218,48 @@ class BaseProfileHandler(BaseHandler):
 
             return result["avatar_url"]
 
-    @defer.inlineCallbacks
-    def set_avatar_url(self, target_user, requester, new_avatar_url, by_admin=False):
+    async def set_avatar_url(
+        self, target_user, requester, new_avatar_url, by_admin=False
+    ):
         """target_user is the user whose avatar_url is to be changed;
         auth_user is the user attempting to make this change."""
         if not self.hs.is_mine(target_user):
-            raise SynapseError(400, "User is not hosted on this Home Server")
+            raise SynapseError(400, "User is not hosted on this homeserver")
 
         if not by_admin and target_user != requester.user:
             raise AuthError(400, "Cannot set another user's avatar_url")
 
+        if not by_admin and not self.hs.config.enable_set_avatar_url:
+            profile = await self.store.get_profileinfo(target_user.localpart)
+            if profile.avatar_url:
+                raise SynapseError(
+                    400, "Changing avatar is disabled on this server", Codes.FORBIDDEN
+                )
+
         if len(new_avatar_url) > MAX_AVATAR_URL_LEN:
             raise SynapseError(
                 400, "Avatar URL is too long (max %i)" % (MAX_AVATAR_URL_LEN,)
             )
 
-        yield self.store.set_profile_avatar_url(target_user.localpart, new_avatar_url)
+        # Same like set_displayname
+        if by_admin:
+            requester = create_requester(target_user)
+
+        await self.store.set_profile_avatar_url(target_user.localpart, new_avatar_url)
 
         if self.hs.config.user_directory_search_all_users:
-            profile = yield self.store.get_profileinfo(target_user.localpart)
-            yield self.user_directory_handler.handle_local_profile_change(
+            profile = await self.store.get_profileinfo(target_user.localpart)
+            await self.user_directory_handler.handle_local_profile_change(
                 target_user.to_string(), profile
             )
 
-        yield self._update_join_states(requester, target_user)
+        await self._update_join_states(requester, target_user)
 
     @defer.inlineCallbacks
     def on_profile_query(self, args):
         user = UserID.from_string(args["user_id"])
         if not self.hs.is_mine(user):
-            raise SynapseError(400, "User is not hosted on this Home Server")
+            raise SynapseError(400, "User is not hosted on this homeserver")
 
         just_field = args.get("field", None)
 
@@ -253,21 +281,20 @@ class BaseProfileHandler(BaseHandler):
 
         return response
 
-    @defer.inlineCallbacks
-    def _update_join_states(self, requester, target_user):
+    async def _update_join_states(self, requester, target_user):
         if not self.hs.is_mine(target_user):
             return
 
-        yield self.ratelimit(requester)
+        await self.ratelimit(requester)
 
-        room_ids = yield self.store.get_rooms_for_user(target_user.to_string())
+        room_ids = await self.store.get_rooms_for_user(target_user.to_string())
 
         for room_id in room_ids:
             handler = self.hs.get_room_member_handler()
             try:
                 # Assume the target_user isn't a guest,
                 # because we don't let guests set profile or avatar data.
-                yield handler.update_membership(
+                await handler.update_membership(
                     requester,
                     target_user,
                     room_id,
@@ -275,7 +302,7 @@ class BaseProfileHandler(BaseHandler):
                     ratelimit=False,  # Try to hide that these events aren't atomic.
                 )
             except Exception as e:
-                logger.warn(
+                logger.warning(
                     "Failed to update join event for room %s - %s", room_id, str(e)
                 )
 
@@ -295,12 +322,16 @@ class BaseProfileHandler(BaseHandler):
                 be found to be in any room the server is in, and therefore the query
                 is denied.
         """
+
         # Implementation of MSC1301: don't allow looking up profiles if the
         # requester isn't in the same room as the target. We expect requester to
         # be None when this function is called outside of a profile query, e.g.
         # when building a membership event. In this case, we must allow the
         # lookup.
-        if not self.hs.config.require_auth_for_profile_requests or not requester:
+        if (
+            not self.hs.config.limit_profile_requests_to_users_who_share_rooms
+            or not requester
+        ):
             return
 
         # Always allow the user to query their own profile.
diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
index 3e4d8c93a4..e3b528d271 100644
--- a/synapse/handlers/read_marker.py
+++ b/synapse/handlers/read_marker.py
@@ -15,8 +15,6 @@
 
 import logging
 
-from twisted.internet import defer
-
 from synapse.util.async_helpers import Linearizer
 
 from ._base import BaseHandler
@@ -32,8 +30,7 @@ class ReadMarkerHandler(BaseHandler):
         self.read_marker_linearizer = Linearizer(name="read_marker")
         self.notifier = hs.get_notifier()
 
-    @defer.inlineCallbacks
-    def received_client_read_marker(self, room_id, user_id, event_id):
+    async def received_client_read_marker(self, room_id, user_id, event_id):
         """Updates the read marker for a given user in a given room if the event ID given
         is ahead in the stream relative to the current read marker.
 
@@ -41,8 +38,8 @@ class ReadMarkerHandler(BaseHandler):
         the read marker has changed.
         """
 
-        with (yield self.read_marker_linearizer.queue((room_id, user_id))):
-            existing_read_marker = yield self.store.get_account_data_for_room_and_type(
+        with await self.read_marker_linearizer.queue((room_id, user_id)):
+            existing_read_marker = await self.store.get_account_data_for_room_and_type(
                 user_id, room_id, "m.fully_read"
             )
 
@@ -50,13 +47,13 @@ class ReadMarkerHandler(BaseHandler):
 
             if existing_read_marker:
                 # Only update if the new marker is ahead in the stream
-                should_update = yield self.store.is_event_after(
+                should_update = await self.store.is_event_after(
                     event_id, existing_read_marker["event_id"]
                 )
 
             if should_update:
                 content = {"event_id": event_id}
-                max_id = yield self.store.add_account_data_to_room(
+                max_id = await self.store.add_account_data_to_room(
                     user_id, room_id, "m.fully_read", content
                 )
                 self.notifier.on_new_event("account_data_key", max_id, users=[user_id])
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index 6854c751a6..8bc100db42 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -18,6 +18,7 @@ from twisted.internet import defer
 
 from synapse.handlers._base import BaseHandler
 from synapse.types import ReadReceipt, get_domain_from_id
+from synapse.util.async_helpers import maybe_awaitable
 
 logger = logging.getLogger(__name__)
 
@@ -36,8 +37,7 @@ class ReceiptsHandler(BaseHandler):
         self.clock = self.hs.get_clock()
         self.state = hs.get_state_handler()
 
-    @defer.inlineCallbacks
-    def _received_remote_receipt(self, origin, content):
+    async def _received_remote_receipt(self, origin, content):
         """Called when we receive an EDU of type m.receipt from a remote HS.
         """
         receipts = []
@@ -62,17 +62,16 @@ class ReceiptsHandler(BaseHandler):
                         )
                     )
 
-        yield self._handle_new_receipts(receipts)
+        await self._handle_new_receipts(receipts)
 
-    @defer.inlineCallbacks
-    def _handle_new_receipts(self, receipts):
+    async def _handle_new_receipts(self, receipts):
         """Takes a list of receipts, stores them and informs the notifier.
         """
         min_batch_id = None
         max_batch_id = None
 
         for receipt in receipts:
-            res = yield self.store.insert_receipt(
+            res = await self.store.insert_receipt(
                 receipt.room_id,
                 receipt.receipt_type,
                 receipt.user_id,
@@ -95,18 +94,19 @@ class ReceiptsHandler(BaseHandler):
             # no new receipts
             return False
 
-        affected_room_ids = list(set([r.room_id for r in receipts]))
+        affected_room_ids = list({r.room_id for r in receipts})
 
         self.notifier.on_new_event("receipt_key", max_batch_id, rooms=affected_room_ids)
         # Note that the min here shouldn't be relied upon to be accurate.
-        yield self.hs.get_pusherpool().on_new_receipts(
-            min_batch_id, max_batch_id, affected_room_ids
+        await maybe_awaitable(
+            self.hs.get_pusherpool().on_new_receipts(
+                min_batch_id, max_batch_id, affected_room_ids
+            )
         )
 
         return True
 
-    @defer.inlineCallbacks
-    def received_client_receipt(self, room_id, receipt_type, user_id, event_id):
+    async def received_client_receipt(self, room_id, receipt_type, user_id, event_id):
         """Called when a client tells us a local user has read up to the given
         event_id in the room.
         """
@@ -118,24 +118,11 @@ class ReceiptsHandler(BaseHandler):
             data={"ts": int(self.clock.time_msec())},
         )
 
-        is_new = yield self._handle_new_receipts([receipt])
+        is_new = await self._handle_new_receipts([receipt])
         if not is_new:
             return
 
-        yield self.federation.send_read_receipt(receipt)
-
-    @defer.inlineCallbacks
-    def get_receipts_for_room(self, room_id, to_key):
-        """Gets all receipts for a room, upto the given key.
-        """
-        result = yield self.store.get_linearized_receipts_for_room(
-            room_id, to_key=to_key
-        )
-
-        if not result:
-            return []
-
-        return result
+        await self.federation.send_read_receipt(receipt)
 
 
 class ReceiptEventSource(object):
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 06bd03b77c..51979ea43e 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -16,18 +16,9 @@
 """Contains functions for registering clients."""
 import logging
 
-from twisted.internet import defer
-
 from synapse import types
 from synapse.api.constants import MAX_USERID_LENGTH, LoginType
-from synapse.api.errors import (
-    AuthError,
-    Codes,
-    ConsentNotGivenError,
-    LimitExceededError,
-    RegistrationError,
-    SynapseError,
-)
+from synapse.api.errors import AuthError, Codes, ConsentNotGivenError, SynapseError
 from synapse.config.server import is_threepid_reserved
 from synapse.http.servlet import assert_params_in_dict
 from synapse.replication.http.login import RegisterDeviceReplicationServlet
@@ -82,8 +73,9 @@ class RegistrationHandler(BaseHandler):
 
         self.session_lifetime = hs.config.session_lifetime
 
-    @defer.inlineCallbacks
-    def check_username(self, localpart, guest_access_token=None, assigned_user_id=None):
+    async def check_username(
+        self, localpart, guest_access_token=None, assigned_user_id=None
+    ):
         if types.contains_invalid_mxid_characters(localpart):
             raise SynapseError(
                 400,
@@ -120,13 +112,13 @@ class RegistrationHandler(BaseHandler):
                 Codes.INVALID_USERNAME,
             )
 
-        users = yield self.store.get_users_by_id_case_insensitive(user_id)
+        users = await self.store.get_users_by_id_case_insensitive(user_id)
         if users:
             if not guest_access_token:
                 raise SynapseError(
                     400, "User ID already taken.", errcode=Codes.USER_IN_USE
                 )
-            user_data = yield self.auth.get_user_by_access_token(guest_access_token)
+            user_data = await self.auth.get_user_by_access_token(guest_access_token)
             if not user_data["is_guest"] or user_data["user"].localpart != localpart:
                 raise AuthError(
                     403,
@@ -135,11 +127,19 @@ class RegistrationHandler(BaseHandler):
                     errcode=Codes.FORBIDDEN,
                 )
 
-    @defer.inlineCallbacks
-    def register_user(
+        if guest_access_token is None:
+            try:
+                int(localpart)
+                raise SynapseError(
+                    400, "Numeric user IDs are reserved for guest users."
+                )
+            except ValueError:
+                pass
+
+    async def register_user(
         self,
         localpart=None,
-        password=None,
+        password_hash=None,
         guest_access_token=None,
         make_guest=False,
         admin=False,
@@ -148,13 +148,14 @@ class RegistrationHandler(BaseHandler):
         default_display_name=None,
         address=None,
         bind_emails=[],
+        by_admin=False,
     ):
         """Registers a new client on the server.
 
         Args:
-            localpart : The local part of the user ID to register. If None,
+            localpart: The local part of the user ID to register. If None,
               one will be generated.
-            password (unicode) : The password to assign to this user so they can
+            password_hash (str|None): The hashed password to assign to this user so they can
               login again. This can be None which means they cannot login again
               via a password (e.g. the user is an application service user).
             user_type (str|None): type of user. One of the values from
@@ -163,31 +164,24 @@ class RegistrationHandler(BaseHandler):
               will be set to this. Defaults to 'localpart'.
             address (str|None): the IP address used to perform the registration.
             bind_emails (List[str]): list of emails to bind to this account.
+            by_admin (bool): True if this registration is being made via the
+              admin api, otherwise False.
         Returns:
-            Deferred[str]: user_id
+            str: user_id
         Raises:
-            RegistrationError if there was a problem registering.
+            SynapseError if there was a problem registering.
         """
+        self.check_registration_ratelimit(address)
 
-        yield self.auth.check_auth_blocking(threepid=threepid)
-        password_hash = None
-        if password:
-            password_hash = yield self._auth_handler.hash(password)
+        # do not check_auth_blocking if the call is coming through the Admin API
+        if not by_admin:
+            await self.auth.check_auth_blocking(threepid=threepid)
 
-        if localpart:
-            yield self.check_username(localpart, guest_access_token=guest_access_token)
+        if localpart is not None:
+            await self.check_username(localpart, guest_access_token=guest_access_token)
 
             was_guest = guest_access_token is not None
 
-            if not was_guest:
-                try:
-                    int(localpart)
-                    raise RegistrationError(
-                        400, "Numeric user IDs are reserved for guest users."
-                    )
-                except ValueError:
-                    pass
-
             user = UserID(localpart, self.hs.hostname)
             user_id = user.to_string()
 
@@ -198,7 +192,7 @@ class RegistrationHandler(BaseHandler):
             elif default_display_name is None:
                 default_display_name = localpart
 
-            yield self.register_with_store(
+            await self.register_with_store(
                 user_id=user_id,
                 password_hash=password_hash,
                 was_guest=was_guest,
@@ -210,38 +204,51 @@ class RegistrationHandler(BaseHandler):
             )
 
             if self.hs.config.user_directory_search_all_users:
-                profile = yield self.store.get_profileinfo(localpart)
-                yield self.user_directory_handler.handle_local_profile_change(
+                profile = await self.store.get_profileinfo(localpart)
+                await self.user_directory_handler.handle_local_profile_change(
                     user_id, profile
                 )
 
         else:
             # autogen a sequential user ID
-            attempts = 0
+            fail_count = 0
             user = None
             while not user:
-                localpart = yield self._generate_user_id(attempts > 0)
+                # Fail after being unable to find a suitable ID a few times
+                if fail_count > 10:
+                    raise SynapseError(500, "Unable to find a suitable guest user ID")
+
+                localpart = await self._generate_user_id()
                 user = UserID(localpart, self.hs.hostname)
                 user_id = user.to_string()
-                yield self.check_user_id_not_appservice_exclusive(user_id)
+                self.check_user_id_not_appservice_exclusive(user_id)
                 if default_display_name is None:
                     default_display_name = localpart
                 try:
-                    yield self.register_with_store(
+                    await self.register_with_store(
                         user_id=user_id,
                         password_hash=password_hash,
                         make_guest=make_guest,
                         create_profile_with_displayname=default_display_name,
                         address=address,
                     )
+
+                    # Successfully registered
+                    break
                 except SynapseError:
                     # if user id is taken, just generate another
                     user = None
                     user_id = None
-                    attempts += 1
+                    fail_count += 1
 
         if not self.hs.config.user_consent_at_registration:
-            yield self._auto_join_rooms(user_id)
+            if not self.hs.config.auto_join_rooms_for_guests and make_guest:
+                logger.info(
+                    "Skipping auto-join for %s because auto-join for guests is disabled",
+                    user_id,
+                )
+            else:
+                await self._auto_join_rooms(user_id)
         else:
             logger.info(
                 "Skipping auto-join for %s because consent is required at registration",
@@ -259,12 +266,11 @@ class RegistrationHandler(BaseHandler):
             }
 
             # Bind email to new account
-            yield self._register_email_threepid(user_id, threepid_dict, None, False)
+            await self._register_email_threepid(user_id, threepid_dict, None)
 
         return user_id
 
-    @defer.inlineCallbacks
-    def _auto_join_rooms(self, user_id):
+    async def _auto_join_rooms(self, user_id):
         """Automatically joins users to auto join rooms - creating the room in the first place
         if the user is the first to be created.
 
@@ -278,9 +284,9 @@ class RegistrationHandler(BaseHandler):
         # that an auto-generated support or bot user is not a real user and will never be
         # the user to create the room
         should_auto_create_rooms = False
-        is_real_user = yield self.store.is_real_user(user_id)
+        is_real_user = await self.store.is_real_user(user_id)
         if self.hs.config.autocreate_auto_join_rooms and is_real_user:
-            count = yield self.store.count_real_users()
+            count = await self.store.count_real_users()
             should_auto_create_rooms = count == 1
         for r in self.hs.config.auto_join_rooms:
             logger.info("Auto-joining %s to %s", user_id, r)
@@ -299,7 +305,7 @@ class RegistrationHandler(BaseHandler):
 
                         # getting the RoomCreationHandler during init gives a dependency
                         # loop
-                        yield self.hs.get_room_creation_handler().create_room(
+                        await self.hs.get_room_creation_handler().create_room(
                             fake_requester,
                             config={
                                 "preset": "public_chat",
@@ -308,7 +314,7 @@ class RegistrationHandler(BaseHandler):
                             ratelimit=False,
                         )
                 else:
-                    yield self._join_user_to_room(fake_requester, r)
+                    await self._join_user_to_room(fake_requester, r)
             except ConsentNotGivenError as e:
                 # Technically not necessary to pull out this error though
                 # moving away from bare excepts is a good thing to do.
@@ -316,18 +322,16 @@ class RegistrationHandler(BaseHandler):
             except Exception as e:
                 logger.error("Failed to join new user to %r: %r", r, e)
 
-    @defer.inlineCallbacks
-    def post_consent_actions(self, user_id):
+    async def post_consent_actions(self, user_id):
         """A series of registration actions that can only be carried out once consent
         has been granted
 
         Args:
             user_id (str): The user to join
         """
-        yield self._auto_join_rooms(user_id)
+        await self._auto_join_rooms(user_id)
 
-    @defer.inlineCallbacks
-    def appservice_register(self, user_localpart, as_token):
+    async def appservice_register(self, user_localpart, as_token):
         user = UserID(user_localpart, self.hs.hostname)
         user_id = user.to_string()
         service = self.store.get_app_service_by_token(as_token)
@@ -342,11 +346,9 @@ class RegistrationHandler(BaseHandler):
 
         service_id = service.id if service.is_exclusive_user(user_id) else None
 
-        yield self.check_user_id_not_appservice_exclusive(
-            user_id, allowed_appservice=service
-        )
+        self.check_user_id_not_appservice_exclusive(user_id, allowed_appservice=service)
 
-        yield self.register_with_store(
+        await self.register_with_store(
             user_id=user_id,
             password_hash="",
             appservice_id=service_id,
@@ -378,28 +380,26 @@ class RegistrationHandler(BaseHandler):
                     errcode=Codes.EXCLUSIVE,
                 )
 
-    @defer.inlineCallbacks
-    def _generate_user_id(self, reseed=False):
-        if reseed or self._next_generated_user_id is None:
-            with (yield self._generate_user_id_linearizer.queue(())):
-                if reseed or self._next_generated_user_id is None:
+    async def _generate_user_id(self):
+        if self._next_generated_user_id is None:
+            with await self._generate_user_id_linearizer.queue(()):
+                if self._next_generated_user_id is None:
                     self._next_generated_user_id = (
-                        yield self.store.find_next_generated_user_id_localpart()
+                        await self.store.find_next_generated_user_id_localpart()
                     )
 
         id = self._next_generated_user_id
         self._next_generated_user_id += 1
         return str(id)
 
-    @defer.inlineCallbacks
-    def _join_user_to_room(self, requester, room_identifier):
+    async def _join_user_to_room(self, requester, room_identifier):
         room_member_handler = self.hs.get_room_member_handler()
         if RoomID.is_valid(room_identifier):
             room_id = room_identifier
         elif RoomAlias.is_valid(room_identifier):
             room_alias = RoomAlias.from_string(room_identifier)
-            room_id, remote_room_hosts = (
-                yield room_member_handler.lookup_room_alias(room_alias)
+            room_id, remote_room_hosts = await room_member_handler.lookup_room_alias(
+                room_alias
             )
             room_id = room_id.to_string()
         else:
@@ -407,7 +407,7 @@ class RegistrationHandler(BaseHandler):
                 400, "%s was not legal room ID or room alias" % (room_identifier,)
             )
 
-        yield room_member_handler.update_membership(
+        await room_member_handler.update_membership(
             requester=requester,
             target=requester.user,
             room_id=room_id,
@@ -416,6 +416,22 @@ class RegistrationHandler(BaseHandler):
             ratelimit=False,
         )
 
+    def check_registration_ratelimit(self, address):
+        """A simple helper method to check whether the registration rate limit has been hit
+        for a given IP address
+
+        Args:
+            address (str|None): the IP address used to perform the registration. If this is
+                None, no ratelimiting will be performed.
+
+        Raises:
+            LimitExceededError: If the rate limit has been exceeded.
+        """
+        if not address:
+            return
+
+        self.ratelimiter.ratelimit(address)
+
     def register_with_store(
         self,
         user_id,
@@ -448,22 +464,6 @@ class RegistrationHandler(BaseHandler):
         Returns:
             Deferred
         """
-        # Don't rate limit for app services
-        if appservice_id is None and address is not None:
-            time_now = self.clock.time()
-
-            allowed, time_allowed = self.ratelimiter.can_do_action(
-                address,
-                time_now_s=time_now,
-                rate_hz=self.hs.config.rc_registration.per_second,
-                burst_count=self.hs.config.rc_registration.burst_count,
-            )
-
-            if not allowed:
-                raise LimitExceededError(
-                    retry_after_ms=int(1000 * (time_allowed - time_now))
-                )
-
         if self.hs.config.worker_app:
             return self._register_client(
                 user_id=user_id,
@@ -488,8 +488,9 @@ class RegistrationHandler(BaseHandler):
                 user_type=user_type,
             )
 
-    @defer.inlineCallbacks
-    def register_device(self, user_id, device_id, initial_display_name, is_guest=False):
+    async def register_device(
+        self, user_id, device_id, initial_display_name, is_guest=False
+    ):
         """Register a device for a user and generate an access token.
 
         The access token will be limited by the homeserver's session_lifetime config.
@@ -503,11 +504,11 @@ class RegistrationHandler(BaseHandler):
             is_guest (bool): Whether this is a guest account
 
         Returns:
-            defer.Deferred[tuple[str, str]]: Tuple of device ID and access token
+            tuple[str, str]: Tuple of device ID and access token
         """
 
         if self.hs.config.worker_app:
-            r = yield self._register_device_client(
+            r = await self._register_device_client(
                 user_id=user_id,
                 device_id=device_id,
                 initial_display_name=initial_display_name,
@@ -523,7 +524,7 @@ class RegistrationHandler(BaseHandler):
                 )
             valid_until_ms = self.clock.time_msec() + self.session_lifetime
 
-        device_id = yield self.device_handler.check_device_registered(
+        device_id = await self.device_handler.check_device_registered(
             user_id, device_id, initial_display_name
         )
         if is_guest:
@@ -532,14 +533,13 @@ class RegistrationHandler(BaseHandler):
                 user_id, ["guest = true"]
             )
         else:
-            access_token = yield self._auth_handler.get_access_token_for_user_id(
+            access_token = await self._auth_handler.get_access_token_for_user_id(
                 user_id, device_id=device_id, valid_until_ms=valid_until_ms
             )
 
         return (device_id, access_token)
 
-    @defer.inlineCallbacks
-    def post_registration_actions(self, user_id, auth_result, access_token):
+    async def post_registration_actions(self, user_id, auth_result, access_token):
         """A user has completed registration
 
         Args:
@@ -550,7 +550,7 @@ class RegistrationHandler(BaseHandler):
                 device, or None if `inhibit_login` enabled.
         """
         if self.hs.config.worker_app:
-            yield self._post_registration_client(
+            await self._post_registration_client(
                 user_id=user_id, auth_result=auth_result, access_token=access_token
             )
             return
@@ -562,19 +562,18 @@ class RegistrationHandler(BaseHandler):
             if is_threepid_reserved(
                 self.hs.config.mau_limits_reserved_threepids, threepid
             ):
-                yield self.store.upsert_monthly_active_user(user_id)
+                await self.store.upsert_monthly_active_user(user_id)
 
-            yield self._register_email_threepid(user_id, threepid, access_token)
+            await self._register_email_threepid(user_id, threepid, access_token)
 
         if auth_result and LoginType.MSISDN in auth_result:
             threepid = auth_result[LoginType.MSISDN]
-            yield self._register_msisdn_threepid(user_id, threepid)
+            await self._register_msisdn_threepid(user_id, threepid)
 
         if auth_result and LoginType.TERMS in auth_result:
-            yield self._on_user_consented(user_id, self.hs.config.user_consent_version)
+            await self._on_user_consented(user_id, self.hs.config.user_consent_version)
 
-    @defer.inlineCallbacks
-    def _on_user_consented(self, user_id, consent_version):
+    async def _on_user_consented(self, user_id, consent_version):
         """A user consented to the terms on registration
 
         Args:
@@ -583,11 +582,10 @@ class RegistrationHandler(BaseHandler):
                 consented to.
         """
         logger.info("%s has consented to the privacy policy", user_id)
-        yield self.store.user_set_consent_version(user_id, consent_version)
-        yield self.post_consent_actions(user_id)
+        await self.store.user_set_consent_version(user_id, consent_version)
+        await self.post_consent_actions(user_id)
 
-    @defer.inlineCallbacks
-    def _register_email_threepid(self, user_id, threepid, token):
+    async def _register_email_threepid(self, user_id, threepid, token):
         """Add an email address as a 3pid identifier
 
         Also adds an email pusher for the email address, if configured in the
@@ -600,8 +598,6 @@ class RegistrationHandler(BaseHandler):
             threepid (object): m.login.email.identity auth response
             token (str|None): access_token for the user, or None if not logged
                 in.
-        Returns:
-            defer.Deferred:
         """
         reqd = ("medium", "address", "validated_at")
         if any(x not in threepid for x in reqd):
@@ -609,14 +605,14 @@ class RegistrationHandler(BaseHandler):
             logger.info("Can't add incomplete 3pid")
             return
 
-        yield self._auth_handler.add_threepid(
-            user_id, threepid["medium"], threepid["address"], threepid["validated_at"]
+        await self._auth_handler.add_threepid(
+            user_id, threepid["medium"], threepid["address"], threepid["validated_at"],
         )
 
         # And we add an email pusher for them by default, but only
         # if email notifications are enabled (so people don't start
         # getting mail spam where they weren't before if email
-        # notifs are set up on a home server)
+        # notifs are set up on a homeserver)
         if (
             self.hs.config.email_enable_notifs
             and self.hs.config.email_notif_for_new_users
@@ -626,10 +622,10 @@ class RegistrationHandler(BaseHandler):
             # It would really make more sense for this to be passed
             # up when the access token is saved, but that's quite an
             # invasive change I'd rather do separately.
-            user_tuple = yield self.store.get_user_by_access_token(token)
+            user_tuple = await self.store.get_user_by_access_token(token)
             token_id = user_tuple["token_id"]
 
-            yield self.pusher_pool.add_pusher(
+            await self.pusher_pool.add_pusher(
                 user_id=user_id,
                 access_token=token_id,
                 kind="email",
@@ -641,8 +637,7 @@ class RegistrationHandler(BaseHandler):
                 data={},
             )
 
-    @defer.inlineCallbacks
-    def _register_msisdn_threepid(self, user_id, threepid):
+    async def _register_msisdn_threepid(self, user_id, threepid):
         """Add a phone number as a 3pid identifier
 
         Must be called on master.
@@ -650,8 +645,6 @@ class RegistrationHandler(BaseHandler):
         Args:
             user_id (str): id of user
             threepid (object): m.login.msisdn auth response
-        Returns:
-            defer.Deferred:
         """
         try:
             assert_params_in_dict(threepid, ["medium", "address", "validated_at"])
@@ -662,6 +655,6 @@ class RegistrationHandler(BaseHandler):
                 return None
             raise
 
-        yield self._auth_handler.add_threepid(
-            user_id, threepid["medium"], threepid["address"], threepid["validated_at"]
+        await self._auth_handler.add_threepid(
+            user_id, threepid["medium"], threepid["address"], threepid["validated_at"],
         )
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 970be3c846..61db3ccc43 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014 - 2016 OpenMarket Ltd
-# Copyright 2018 New Vector Ltd
+# Copyright 2018-2019 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -15,21 +16,31 @@
 # limitations under the License.
 
 """Contains functions for performing events on rooms."""
+
 import itertools
 import logging
 import math
 import string
 from collections import OrderedDict
+from typing import Tuple
 
 from six import iteritems, string_types
 
-from twisted.internet import defer
-
 from synapse.api.constants import EventTypes, JoinRules, RoomCreationPreset
 from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError
-from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
+from synapse.events.utils import copy_power_levels_contents
+from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.storage.state import StateFilter
-from synapse.types import RoomAlias, RoomID, RoomStreamToken, StreamToken, UserID
+from synapse.types import (
+    Requester,
+    RoomAlias,
+    RoomID,
+    RoomStreamToken,
+    StateMap,
+    StreamToken,
+    UserID,
+)
 from synapse.util import stringutils
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches.response_cache import ResponseCache
@@ -52,18 +63,21 @@ class RoomCreationHandler(BaseHandler):
             "history_visibility": "shared",
             "original_invitees_have_ops": False,
             "guest_can_join": True,
+            "power_level_content_override": {"invite": 0},
         },
         RoomCreationPreset.TRUSTED_PRIVATE_CHAT: {
             "join_rules": JoinRules.INVITE,
             "history_visibility": "shared",
             "original_invitees_have_ops": True,
             "guest_can_join": True,
+            "power_level_content_override": {"invite": 0},
         },
         RoomCreationPreset.PUBLIC_CHAT: {
             "join_rules": JoinRules.PUBLIC,
             "history_visibility": "shared",
             "original_invitees_have_ops": False,
             "guest_can_join": False,
+            "power_level_content_override": {},
         },
     }
 
@@ -75,6 +89,8 @@ class RoomCreationHandler(BaseHandler):
         self.room_member_handler = hs.get_room_member_handler()
         self.config = hs.config
 
+        self._replication = hs.get_replication_data_handler()
+
         # linearizer to stop two upgrades happening at once
         self._upgrade_linearizer = Linearizer("room_upgrade_linearizer")
 
@@ -88,19 +104,20 @@ class RoomCreationHandler(BaseHandler):
 
         self.third_party_event_rules = hs.get_third_party_event_rules()
 
-    @defer.inlineCallbacks
-    def upgrade_room(self, requester, old_room_id, new_version):
+    async def upgrade_room(
+        self, requester: Requester, old_room_id: str, new_version: RoomVersion
+    ):
         """Replace a room with a new room with a different version
 
         Args:
-            requester (synapse.types.Requester): the user requesting the upgrade
-            old_room_id (unicode): the id of the room to be replaced
-            new_version (unicode): the new room version to use
+            requester: the user requesting the upgrade
+            old_room_id: the id of the room to be replaced
+            new_version: the new room version to use
 
         Returns:
             Deferred[unicode]: the new room id
         """
-        yield self.ratelimit(requester)
+        await self.ratelimit(requester)
 
         user_id = requester.user.to_string()
 
@@ -121,53 +138,56 @@ class RoomCreationHandler(BaseHandler):
         # If this user has sent multiple upgrade requests for the same room
         # and one of them is not complete yet, cache the response and
         # return it to all subsequent requests
-        ret = yield self._upgrade_response_cache.wrap(
+        ret = await self._upgrade_response_cache.wrap(
             (old_room_id, user_id),
             self._upgrade_room,
             requester,
             old_room_id,
             new_version,  # args for _upgrade_room
         )
+
         return ret
 
-    @defer.inlineCallbacks
-    def _upgrade_room(self, requester, old_room_id, new_version):
+    async def _upgrade_room(
+        self, requester: Requester, old_room_id: str, new_version: RoomVersion
+    ):
         user_id = requester.user.to_string()
 
         # start by allocating a new room id
-        r = yield self.store.get_room(old_room_id)
+        r = await self.store.get_room(old_room_id)
         if r is None:
             raise NotFoundError("Unknown room id %s" % (old_room_id,))
-        new_room_id = yield self._generate_room_id(
-            creator_id=user_id, is_public=r["is_public"]
+        new_room_id = await self._generate_room_id(
+            creator_id=user_id, is_public=r["is_public"], room_version=new_version,
         )
 
         logger.info("Creating new room %s to replace %s", new_room_id, old_room_id)
 
         # we create and auth the tombstone event before properly creating the new
         # room, to check our user has perms in the old room.
-        tombstone_event, tombstone_context = (
-            yield self.event_creation_handler.create_event(
-                requester,
-                {
-                    "type": EventTypes.Tombstone,
-                    "state_key": "",
-                    "room_id": old_room_id,
-                    "sender": user_id,
-                    "content": {
-                        "body": "This room has been replaced",
-                        "replacement_room": new_room_id,
-                    },
+        (
+            tombstone_event,
+            tombstone_context,
+        ) = await self.event_creation_handler.create_event(
+            requester,
+            {
+                "type": EventTypes.Tombstone,
+                "state_key": "",
+                "room_id": old_room_id,
+                "sender": user_id,
+                "content": {
+                    "body": "This room has been replaced",
+                    "replacement_room": new_room_id,
                 },
-                token_id=requester.access_token_id,
-            )
+            },
+            token_id=requester.access_token_id,
         )
-        old_room_version = yield self.store.get_room_version(old_room_id)
-        yield self.auth.check_from_context(
+        old_room_version = await self.store.get_room_version_id(old_room_id)
+        await self.auth.check_from_context(
             old_room_version, tombstone_event, tombstone_context
         )
 
-        yield self.clone_existing_room(
+        await self.clone_existing_room(
             requester,
             old_room_id=old_room_id,
             new_room_id=new_room_id,
@@ -176,36 +196,44 @@ class RoomCreationHandler(BaseHandler):
         )
 
         # now send the tombstone
-        yield self.event_creation_handler.send_nonmember_event(
+        await self.event_creation_handler.send_nonmember_event(
             requester, tombstone_event, tombstone_context
         )
 
-        old_room_state = yield tombstone_context.get_current_state_ids(self.store)
+        old_room_state = await tombstone_context.get_current_state_ids()
 
         # update any aliases
-        yield self._move_aliases_to_new_room(
+        await self._move_aliases_to_new_room(
             requester, old_room_id, new_room_id, old_room_state
         )
 
-        # and finally, shut down the PLs in the old room, and update them in the new
+        # Copy over user push rules, tags and migrate room directory state
+        await self.room_member_handler.transfer_room_state_on_room_upgrade(
+            old_room_id, new_room_id
+        )
+
+        # finally, shut down the PLs in the old room, and update them in the new
         # room.
-        yield self._update_upgraded_room_pls(
-            requester, old_room_id, new_room_id, old_room_state
+        await self._update_upgraded_room_pls(
+            requester, old_room_id, new_room_id, old_room_state,
         )
 
         return new_room_id
 
-    @defer.inlineCallbacks
-    def _update_upgraded_room_pls(
-        self, requester, old_room_id, new_room_id, old_room_state
+    async def _update_upgraded_room_pls(
+        self,
+        requester: Requester,
+        old_room_id: str,
+        new_room_id: str,
+        old_room_state: StateMap[str],
     ):
         """Send updated power levels in both rooms after an upgrade
 
         Args:
-            requester (synapse.types.Requester): the user requesting the upgrade
-            old_room_id (unicode): the id of the room to be replaced
-            new_room_id (unicode): the id of the replacement room
-            old_room_state (dict[tuple[str, str], str]): the state map for the old room
+            requester: the user requesting the upgrade
+            old_room_id: the id of the room to be replaced
+            new_room_id: the id of the replacement room
+            old_room_state: the state map for the old room
 
         Returns:
             Deferred
@@ -219,7 +247,7 @@ class RoomCreationHandler(BaseHandler):
             )
             return
 
-        old_room_pl_state = yield self.store.get_event(old_room_pl_event_id)
+        old_room_pl_state = await self.store.get_event(old_room_pl_event_id)
 
         # we try to stop regular users from speaking by setting the PL required
         # to send regular events and invites to 'Moderator' level. That's normally
@@ -234,7 +262,7 @@ class RoomCreationHandler(BaseHandler):
         for v in ("invite", "events_default"):
             current = int(pl_content.get(v, 0))
             if current < restricted_level:
-                logger.info(
+                logger.debug(
                     "Setting level for %s in %s to %i (was %i)",
                     v,
                     old_room_id,
@@ -244,11 +272,11 @@ class RoomCreationHandler(BaseHandler):
                 pl_content[v] = restricted_level
                 updated = True
             else:
-                logger.info("Not setting level for %s (already %i)", v, current)
+                logger.debug("Not setting level for %s (already %i)", v, current)
 
         if updated:
             try:
-                yield self.event_creation_handler.create_and_send_nonmember_event(
+                await self.event_creation_handler.create_and_send_nonmember_event(
                     requester,
                     {
                         "type": EventTypes.PowerLevels,
@@ -262,8 +290,7 @@ class RoomCreationHandler(BaseHandler):
             except AuthError as e:
                 logger.warning("Unable to update PLs in old room: %s", e)
 
-        logger.info("Setting correct PLs in new room")
-        yield self.event_creation_handler.create_and_send_nonmember_event(
+        await self.event_creation_handler.create_and_send_nonmember_event(
             requester,
             {
                 "type": EventTypes.PowerLevels,
@@ -275,22 +302,25 @@ class RoomCreationHandler(BaseHandler):
             ratelimit=False,
         )
 
-    @defer.inlineCallbacks
-    def clone_existing_room(
-        self, requester, old_room_id, new_room_id, new_room_version, tombstone_event_id
+    async def clone_existing_room(
+        self,
+        requester: Requester,
+        old_room_id: str,
+        new_room_id: str,
+        new_room_version: RoomVersion,
+        tombstone_event_id: str,
     ):
         """Populate a new room based on an old room
 
         Args:
-            requester (synapse.types.Requester): the user requesting the upgrade
-            old_room_id (unicode): the id of the room to be replaced
-            new_room_id (unicode): the id to give the new room (should already have been
+            requester: the user requesting the upgrade
+            old_room_id : the id of the room to be replaced
+            new_room_id: the id to give the new room (should already have been
                 created with _gemerate_room_id())
-            new_room_version (unicode): the new room version to use
-            tombstone_event_id (unicode|str): the ID of the tombstone event in the old
-                room.
+            new_room_version: the new room version to use
+            tombstone_event_id: the ID of the tombstone event in the old room.
         Returns:
-            Deferred[None]
+            Deferred
         """
         user_id = requester.user.to_string()
 
@@ -298,21 +328,21 @@ class RoomCreationHandler(BaseHandler):
             raise SynapseError(403, "You are not permitted to create rooms")
 
         creation_content = {
-            "room_version": new_room_version,
+            "room_version": new_room_version.identifier,
             "predecessor": {"room_id": old_room_id, "event_id": tombstone_event_id},
         }
 
         # Check if old room was non-federatable
 
         # Get old room's create event
-        old_room_create_event = yield self.store.get_create_event_for_room(old_room_id)
+        old_room_create_event = await self.store.get_create_event_for_room(old_room_id)
 
         # Check if the create event specified a non-federatable room
         if not old_room_create_event.content.get("m.federate", True):
             # If so, mark the new room as non-federatable as well
             creation_content["m.federate"] = False
 
-        initial_state = dict()
+        initial_state = {}
 
         # Replicate relevant room events
         types_to_copy = (
@@ -322,23 +352,52 @@ class RoomCreationHandler(BaseHandler):
             (EventTypes.RoomHistoryVisibility, ""),
             (EventTypes.GuestAccess, ""),
             (EventTypes.RoomAvatar, ""),
-            (EventTypes.Encryption, ""),
+            (EventTypes.RoomEncryption, ""),
             (EventTypes.ServerACL, ""),
             (EventTypes.RelatedGroups, ""),
+            (EventTypes.PowerLevels, ""),
         )
 
-        old_room_state_ids = yield self.store.get_filtered_current_state_ids(
+        old_room_state_ids = await self.store.get_filtered_current_state_ids(
             old_room_id, StateFilter.from_types(types_to_copy)
         )
         # map from event_id to BaseEvent
-        old_room_state_events = yield self.store.get_events(old_room_state_ids.values())
+        old_room_state_events = await self.store.get_events(old_room_state_ids.values())
 
         for k, old_event_id in iteritems(old_room_state_ids):
             old_event = old_room_state_events.get(old_event_id)
             if old_event:
                 initial_state[k] = old_event.content
 
-        yield self._send_events_for_new_room(
+        # deep-copy the power-levels event before we start modifying it
+        # note that if frozen_dicts are enabled, `power_levels` will be a frozen
+        # dict so we can't just copy.deepcopy it.
+        initial_state[
+            (EventTypes.PowerLevels, "")
+        ] = power_levels = copy_power_levels_contents(
+            initial_state[(EventTypes.PowerLevels, "")]
+        )
+
+        # Resolve the minimum power level required to send any state event
+        # We will give the upgrading user this power level temporarily (if necessary) such that
+        # they are able to copy all of the state events over, then revert them back to their
+        # original power level afterwards in _update_upgraded_room_pls
+
+        # Copy over user power levels now as this will not be possible with >100PL users once
+        # the room has been created
+
+        # Calculate the minimum power level needed to clone the room
+        event_power_levels = power_levels.get("events", {})
+        state_default = power_levels.get("state_default", 0)
+        ban = power_levels.get("ban")
+        needed_power_level = max(state_default, ban, max(event_power_levels.values()))
+
+        # Raise the requester's power level in the new room if necessary
+        current_power_level = power_levels["users"][user_id]
+        if current_power_level < needed_power_level:
+            power_levels["users"][user_id] = needed_power_level
+
+        await self._send_events_for_new_room(
             requester,
             new_room_id,
             # we expect to override all the presets with initial_state, so this is
@@ -350,12 +409,12 @@ class RoomCreationHandler(BaseHandler):
         )
 
         # Transfer membership events
-        old_room_member_state_ids = yield self.store.get_filtered_current_state_ids(
+        old_room_member_state_ids = await self.store.get_filtered_current_state_ids(
             old_room_id, StateFilter.from_types([(EventTypes.Member, None)])
         )
 
         # map from event_id to BaseEvent
-        old_room_member_state_events = yield self.store.get_events(
+        old_room_member_state_events = await self.store.get_events(
             old_room_member_state_ids.values()
         )
         for k, old_event in iteritems(old_room_member_state_events):
@@ -364,7 +423,7 @@ class RoomCreationHandler(BaseHandler):
                 "membership" in old_event.content
                 and old_event.content["membership"] == "ban"
             ):
-                yield self.room_member_handler.update_membership(
+                await self.room_member_handler.update_membership(
                     requester,
                     UserID.from_string(old_event["state_key"]),
                     new_room_id,
@@ -376,102 +435,93 @@ class RoomCreationHandler(BaseHandler):
         # XXX invites/joins
         # XXX 3pid invites
 
-    @defer.inlineCallbacks
-    def _move_aliases_to_new_room(
-        self, requester, old_room_id, new_room_id, old_room_state
+    async def _move_aliases_to_new_room(
+        self,
+        requester: Requester,
+        old_room_id: str,
+        new_room_id: str,
+        old_room_state: StateMap[str],
     ):
-        directory_handler = self.hs.get_handlers().directory_handler
-
-        aliases = yield self.store.get_aliases_for_room(old_room_id)
-
         # check to see if we have a canonical alias.
-        canonical_alias = None
+        canonical_alias_event = None
         canonical_alias_event_id = old_room_state.get((EventTypes.CanonicalAlias, ""))
         if canonical_alias_event_id:
-            canonical_alias_event = yield self.store.get_event(canonical_alias_event_id)
-            if canonical_alias_event:
-                canonical_alias = canonical_alias_event.content.get("alias", "")
+            canonical_alias_event = await self.store.get_event(canonical_alias_event_id)
 
-        # first we try to remove the aliases from the old room (we suppress sending
-        # the room_aliases event until the end).
-        #
-        # Note that we'll only be able to remove aliases that (a) aren't owned by an AS,
-        # and (b) unless the user is a server admin, which the user created.
-        #
-        # This is probably correct - given we don't allow such aliases to be deleted
-        # normally, it would be odd to allow it in the case of doing a room upgrade -
-        # but it makes the upgrade less effective, and you have to wonder why a room
-        # admin can't remove aliases that point to that room anyway.
-        # (cf https://github.com/matrix-org/synapse/issues/2360)
-        #
-        removed_aliases = []
-        for alias_str in aliases:
-            alias = RoomAlias.from_string(alias_str)
-            try:
-                yield directory_handler.delete_association(
-                    requester, alias, send_event=False
-                )
-                removed_aliases.append(alias_str)
-            except SynapseError as e:
-                logger.warning("Unable to remove alias %s from old room: %s", alias, e)
+        await self.store.update_aliases_for_room(old_room_id, new_room_id)
 
-        # if we didn't find any aliases, or couldn't remove anyway, we can skip the rest
-        # of this.
-        if not removed_aliases:
+        if not canonical_alias_event:
             return
 
+        # If there is a canonical alias we need to update the one in the old
+        # room and set one in the new one.
+        old_canonical_alias_content = dict(canonical_alias_event.content)
+        new_canonical_alias_content = {}
+
+        canonical = canonical_alias_event.content.get("alias")
+        if canonical and self.hs.is_mine_id(canonical):
+            new_canonical_alias_content["alias"] = canonical
+            old_canonical_alias_content.pop("alias", None)
+
+        # We convert to a list as it will be a Tuple.
+        old_alt_aliases = list(old_canonical_alias_content.get("alt_aliases", []))
+        if old_alt_aliases:
+            old_canonical_alias_content["alt_aliases"] = old_alt_aliases
+            new_alt_aliases = new_canonical_alias_content.setdefault("alt_aliases", [])
+            for alias in canonical_alias_event.content.get("alt_aliases", []):
+                try:
+                    if self.hs.is_mine_id(alias):
+                        new_alt_aliases.append(alias)
+                        old_alt_aliases.remove(alias)
+                except Exception:
+                    logger.info(
+                        "Invalid alias %s in canonical alias event %s",
+                        alias,
+                        canonical_alias_event_id,
+                    )
+
+            if not old_alt_aliases:
+                old_canonical_alias_content.pop("alt_aliases")
+
+        # If a canonical alias event existed for the old room, fire a canonical
+        # alias event for the new room with a copy of the information.
         try:
-            # this can fail if, for some reason, our user doesn't have perms to send
-            # m.room.aliases events in the old room (note that we've already checked that
-            # they have perms to send a tombstone event, so that's not terribly likely).
-            #
-            # If that happens, it's regrettable, but we should carry on: it's the same
-            # as when you remove an alias from the directory normally - it just means that
-            # the aliases event gets out of sync with the directory
-            # (cf https://github.com/vector-im/riot-web/issues/2369)
-            yield directory_handler.send_room_alias_update_event(requester, old_room_id)
-        except AuthError as e:
-            logger.warning("Failed to send updated alias event on old room: %s", e)
-
-        # we can now add any aliases we successfully removed to the new room.
-        for alias in removed_aliases:
-            try:
-                yield directory_handler.create_association(
-                    requester,
-                    RoomAlias.from_string(alias),
-                    new_room_id,
-                    servers=(self.hs.hostname,),
-                    send_event=False,
-                    check_membership=False,
-                )
-                logger.info("Moved alias %s to new room", alias)
-            except SynapseError as e:
-                # I'm not really expecting this to happen, but it could if the spam
-                # checking module decides it shouldn't, or similar.
-                logger.error("Error adding alias %s to new room: %s", alias, e)
+            await self.event_creation_handler.create_and_send_nonmember_event(
+                requester,
+                {
+                    "type": EventTypes.CanonicalAlias,
+                    "state_key": "",
+                    "room_id": old_room_id,
+                    "sender": requester.user.to_string(),
+                    "content": old_canonical_alias_content,
+                },
+                ratelimit=False,
+            )
+        except SynapseError as e:
+            # again I'm not really expecting this to fail, but if it does, I'd rather
+            # we returned the new room to the client at this point.
+            logger.error("Unable to send updated alias events in old room: %s", e)
 
         try:
-            if canonical_alias and (canonical_alias in removed_aliases):
-                yield self.event_creation_handler.create_and_send_nonmember_event(
-                    requester,
-                    {
-                        "type": EventTypes.CanonicalAlias,
-                        "state_key": "",
-                        "room_id": new_room_id,
-                        "sender": requester.user.to_string(),
-                        "content": {"alias": canonical_alias},
-                    },
-                    ratelimit=False,
-                )
-
-            yield directory_handler.send_room_alias_update_event(requester, new_room_id)
+            await self.event_creation_handler.create_and_send_nonmember_event(
+                requester,
+                {
+                    "type": EventTypes.CanonicalAlias,
+                    "state_key": "",
+                    "room_id": new_room_id,
+                    "sender": requester.user.to_string(),
+                    "content": new_canonical_alias_content,
+                },
+                ratelimit=False,
+            )
         except SynapseError as e:
             # again I'm not really expecting this to fail, but if it does, I'd rather
             # we returned the new room to the client at this point.
             logger.error("Unable to send updated alias events in new room: %s", e)
 
-    @defer.inlineCallbacks
-    def create_room(self, requester, config, ratelimit=True, creator_join_profile=None):
+    async def create_room(
+        self, requester, config, ratelimit=True, creator_join_profile=None
+    ) -> Tuple[dict, int]:
         """ Creates a new room.
 
         Args:
@@ -488,9 +538,9 @@ class RoomCreationHandler(BaseHandler):
                 `avatar_url` and/or `displayname`.
 
         Returns:
-            Deferred[dict]:
-                a dict containing the keys `room_id` and, if an alias was
-                requested, `room_alias`.
+                First, a dict containing the keys `room_id` and, if an alias
+                was, requested, `room_alias`. Secondly, the stream_id of the
+                last persisted event.
         Raises:
             SynapseError if the room ID couldn't be stored, or something went
             horribly wrong.
@@ -499,7 +549,7 @@ class RoomCreationHandler(BaseHandler):
         """
         user_id = requester.user.to_string()
 
-        yield self.auth.check_auth_blocking(user_id)
+        await self.auth.check_auth_blocking(user_id)
 
         if (
             self._server_notices_mxid is not None
@@ -508,13 +558,17 @@ class RoomCreationHandler(BaseHandler):
             # allow the server notices mxid to create rooms
             is_requester_admin = True
         else:
-            is_requester_admin = yield self.auth.is_server_admin(requester.user)
+            is_requester_admin = await self.auth.is_server_admin(requester.user)
 
         # Check whether the third party rules allows/changes the room create
         # request.
-        yield self.third_party_event_rules.on_create_room(
+        event_allowed = await self.third_party_event_rules.on_create_room(
             requester, config, is_requester_admin=is_requester_admin
         )
+        if not event_allowed:
+            raise SynapseError(
+                403, "You are not permitted to create rooms", Codes.FORBIDDEN
+            )
 
         if not is_requester_admin and not self.spam_checker.user_may_create_room(
             user_id
@@ -522,16 +576,17 @@ class RoomCreationHandler(BaseHandler):
             raise SynapseError(403, "You are not permitted to create rooms")
 
         if ratelimit:
-            yield self.ratelimit(requester)
+            await self.ratelimit(requester)
 
-        room_version = config.get(
+        room_version_id = config.get(
             "room_version", self.config.default_room_version.identifier
         )
 
-        if not isinstance(room_version, string_types):
+        if not isinstance(room_version_id, string_types):
             raise SynapseError(400, "room_version must be a string", Codes.BAD_JSON)
 
-        if room_version not in KNOWN_ROOM_VERSIONS:
+        room_version = KNOWN_ROOM_VERSIONS.get(room_version_id)
+        if room_version is None:
             raise SynapseError(
                 400,
                 "Your homeserver does not support this room version",
@@ -544,7 +599,7 @@ class RoomCreationHandler(BaseHandler):
                     raise SynapseError(400, "Invalid characters in room alias")
 
             room_alias = RoomAlias(config["room_alias_name"], self.hs.hostname)
-            mapping = yield self.store.get_association_from_room_alias(room_alias)
+            mapping = await self.store.get_association_from_room_alias(room_alias)
 
             if mapping:
                 raise SynapseError(400, "Room alias already taken", Codes.ROOM_IN_USE)
@@ -554,11 +609,12 @@ class RoomCreationHandler(BaseHandler):
         invite_list = config.get("invite", [])
         for i in invite_list:
             try:
-                UserID.from_string(i)
+                uid = UserID.from_string(i)
+                parse_and_validate_server_name(uid.domain)
             except Exception:
                 raise SynapseError(400, "Invalid user_id: %s" % (i,))
 
-        yield self.event_creation_handler.assert_accepted_privacy_policy(requester)
+        await self.event_creation_handler.assert_accepted_privacy_policy(requester)
 
         power_level_content_override = config.get("power_level_content_override")
         if (
@@ -577,19 +633,27 @@ class RoomCreationHandler(BaseHandler):
         visibility = config.get("visibility", None)
         is_public = visibility == "public"
 
-        room_id = yield self._generate_room_id(creator_id=user_id, is_public=is_public)
+        room_id = await self._generate_room_id(
+            creator_id=user_id, is_public=is_public, room_version=room_version,
+        )
 
         directory_handler = self.hs.get_handlers().directory_handler
         if room_alias:
-            yield directory_handler.create_association(
+            await directory_handler.create_association(
                 requester=requester,
                 room_id=room_id,
                 room_alias=room_alias,
                 servers=[self.hs.hostname],
-                send_event=False,
                 check_membership=False,
             )
 
+        if is_public:
+            if not self.config.is_publishing_room_allowed(user_id, room_id, room_alias):
+                # Lets just return a generic message, as there may be all sorts of
+                # reasons why we said no. TODO: Allow configurable error messages
+                # per alias creation rule?
+                raise SynapseError(403, "Not allowed to publish room")
+
         preset_config = config.get(
             "preset",
             RoomCreationPreset.PRIVATE_CHAT
@@ -606,9 +670,9 @@ class RoomCreationHandler(BaseHandler):
         creation_content = config.get("creation_content", {})
 
         # override any attempt to set room versions via the creation_content
-        creation_content["room_version"] = room_version
+        creation_content["room_version"] = room_version.identifier
 
-        yield self._send_events_for_new_room(
+        last_stream_id = await self._send_events_for_new_room(
             requester,
             room_id,
             preset_config=preset_config,
@@ -622,7 +686,10 @@ class RoomCreationHandler(BaseHandler):
 
         if "name" in config:
             name = config["name"]
-            yield self.event_creation_handler.create_and_send_nonmember_event(
+            (
+                _,
+                last_stream_id,
+            ) = await self.event_creation_handler.create_and_send_nonmember_event(
                 requester,
                 {
                     "type": EventTypes.Name,
@@ -636,7 +703,10 @@ class RoomCreationHandler(BaseHandler):
 
         if "topic" in config:
             topic = config["topic"]
-            yield self.event_creation_handler.create_and_send_nonmember_event(
+            (
+                _,
+                last_stream_id,
+            ) = await self.event_creation_handler.create_and_send_nonmember_event(
                 requester,
                 {
                     "type": EventTypes.Topic,
@@ -654,7 +724,7 @@ class RoomCreationHandler(BaseHandler):
             if is_direct:
                 content["is_direct"] = is_direct
 
-            yield self.room_member_handler.update_membership(
+            _, last_stream_id = await self.room_member_handler.update_membership(
                 requester,
                 UserID.from_string(invitee),
                 room_id,
@@ -668,7 +738,7 @@ class RoomCreationHandler(BaseHandler):
             id_access_token = invite_3pid.get("id_access_token")  # optional
             address = invite_3pid["address"]
             medium = invite_3pid["medium"]
-            yield self.hs.get_room_member_handler().do_3pid_invite(
+            last_stream_id = await self.hs.get_room_member_handler().do_3pid_invite(
                 room_id,
                 requester.user,
                 medium,
@@ -683,12 +753,15 @@ class RoomCreationHandler(BaseHandler):
 
         if room_alias:
             result["room_alias"] = room_alias.to_string()
-            yield directory_handler.send_room_alias_update_event(requester, room_id)
 
-        return result
+        # Always wait for room creation to progate before returning
+        await self._replication.wait_for_stream_position(
+            self.hs.config.worker.writers.events, "events", last_stream_id
+        )
+
+        return result, last_stream_id
 
-    @defer.inlineCallbacks
-    def _send_events_for_new_room(
+    async def _send_events_for_new_room(
         self,
         creator,  # A Requester object.
         room_id,
@@ -697,9 +770,15 @@ class RoomCreationHandler(BaseHandler):
         initial_state,
         creation_content,
         room_alias=None,
-        power_level_content_override=None,
+        power_level_content_override=None,  # Doesn't apply when initial state has power level state event content
         creator_join_profile=None,
-    ):
+    ) -> int:
+        """Sends the initial events into a new room.
+
+        Returns:
+            The stream_id of the last event persisted.
+        """
+
         def create(etype, content, **kwargs):
             e = {"type": etype, "content": content}
 
@@ -708,13 +787,16 @@ class RoomCreationHandler(BaseHandler):
 
             return e
 
-        @defer.inlineCallbacks
-        def send(etype, content, **kwargs):
+        async def send(etype, content, **kwargs) -> int:
             event = create(etype, content, **kwargs)
-            logger.info("Sending %s in new room", etype)
-            yield self.event_creation_handler.create_and_send_nonmember_event(
+            logger.debug("Sending %s in new room", etype)
+            (
+                _,
+                last_stream_id,
+            ) = await self.event_creation_handler.create_and_send_nonmember_event(
                 creator, event, ratelimit=False
             )
+            return last_stream_id
 
         config = RoomCreationHandler.PRESETS_DICT[preset_config]
 
@@ -723,10 +805,10 @@ class RoomCreationHandler(BaseHandler):
         event_keys = {"room_id": room_id, "sender": creator_id, "state_key": ""}
 
         creation_content.update({"creator": creator_id})
-        yield send(etype=EventTypes.Create, content=creation_content)
+        await send(etype=EventTypes.Create, content=creation_content)
 
-        logger.info("Sending %s in new room", EventTypes.Member)
-        yield self.room_member_handler.update_membership(
+        logger.debug("Sending %s in new room", EventTypes.Member)
+        await self.room_member_handler.update_membership(
             creator,
             creator.user,
             room_id,
@@ -739,7 +821,9 @@ class RoomCreationHandler(BaseHandler):
         # of the first events that get sent into a room.
         pl_content = initial_state.pop((EventTypes.PowerLevels, ""), None)
         if pl_content is not None:
-            yield send(etype=EventTypes.PowerLevels, content=pl_content)
+            last_sent_stream_id = await send(
+                etype=EventTypes.PowerLevels, content=pl_content
+            )
         else:
             power_level_content = {
                 "users": {creator_id: 100},
@@ -750,52 +834,65 @@ class RoomCreationHandler(BaseHandler):
                     EventTypes.RoomHistoryVisibility: 100,
                     EventTypes.CanonicalAlias: 50,
                     EventTypes.RoomAvatar: 50,
+                    EventTypes.Tombstone: 100,
+                    EventTypes.ServerACL: 100,
+                    EventTypes.RoomEncryption: 100,
                 },
                 "events_default": 0,
                 "state_default": 50,
                 "ban": 50,
                 "kick": 50,
                 "redact": 50,
-                "invite": 0,
+                "invite": 50,
             }
 
             if config["original_invitees_have_ops"]:
                 for invitee in invite_list:
                     power_level_content["users"][invitee] = 100
 
+            # Power levels overrides are defined per chat preset
+            power_level_content.update(config["power_level_content_override"])
+
             if power_level_content_override:
                 power_level_content.update(power_level_content_override)
 
-            yield send(etype=EventTypes.PowerLevels, content=power_level_content)
+            last_sent_stream_id = await send(
+                etype=EventTypes.PowerLevels, content=power_level_content
+            )
 
         if room_alias and (EventTypes.CanonicalAlias, "") not in initial_state:
-            yield send(
+            last_sent_stream_id = await send(
                 etype=EventTypes.CanonicalAlias,
                 content={"alias": room_alias.to_string()},
             )
 
         if (EventTypes.JoinRules, "") not in initial_state:
-            yield send(
+            last_sent_stream_id = await send(
                 etype=EventTypes.JoinRules, content={"join_rule": config["join_rules"]}
             )
 
         if (EventTypes.RoomHistoryVisibility, "") not in initial_state:
-            yield send(
+            last_sent_stream_id = await send(
                 etype=EventTypes.RoomHistoryVisibility,
                 content={"history_visibility": config["history_visibility"]},
             )
 
         if config["guest_can_join"]:
             if (EventTypes.GuestAccess, "") not in initial_state:
-                yield send(
+                last_sent_stream_id = await send(
                     etype=EventTypes.GuestAccess, content={"guest_access": "can_join"}
                 )
 
         for (etype, state_key), content in initial_state.items():
-            yield send(etype=etype, state_key=state_key, content=content)
+            last_sent_stream_id = await send(
+                etype=etype, state_key=state_key, content=content
+            )
 
-    @defer.inlineCallbacks
-    def _generate_room_id(self, creator_id, is_public):
+        return last_sent_stream_id
+
+    async def _generate_room_id(
+        self, creator_id: str, is_public: str, room_version: RoomVersion,
+    ):
         # autogen room IDs and try to create it. We may clash, so just
         # try a few times till one goes through, giving up eventually.
         attempts = 0
@@ -805,10 +902,11 @@ class RoomCreationHandler(BaseHandler):
                 gen_room_id = RoomID(random_string, self.hs.hostname).to_string()
                 if isinstance(gen_room_id, bytes):
                     gen_room_id = gen_room_id.decode("utf-8")
-                yield self.store.store_room(
+                await self.store.store_room(
                     room_id=gen_room_id,
                     room_creator_user_id=creator_id,
                     is_public=is_public,
+                    room_version=room_version,
                 )
                 return gen_room_id
             except StoreError:
@@ -820,9 +918,10 @@ class RoomContextHandler(object):
     def __init__(self, hs):
         self.hs = hs
         self.store = hs.get_datastore()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
 
-    @defer.inlineCallbacks
-    def get_event_context(self, user, room_id, event_id, limit, event_filter):
+    async def get_event_context(self, user, room_id, event_id, limit, event_filter):
         """Retrieves events, pagination tokens and state around a given event
         in a room.
 
@@ -841,31 +940,38 @@ class RoomContextHandler(object):
         before_limit = math.floor(limit / 2.0)
         after_limit = limit - before_limit
 
-        users = yield self.store.get_users_in_room(room_id)
+        users = await self.store.get_users_in_room(room_id)
         is_peeking = user.to_string() not in users
 
         def filter_evts(events):
             return filter_events_for_client(
-                self.store, user.to_string(), events, is_peeking=is_peeking
+                self.storage, user.to_string(), events, is_peeking=is_peeking
             )
 
-        event = yield self.store.get_event(
+        event = await self.store.get_event(
             event_id, get_prev_content=True, allow_none=True
         )
         if not event:
             return None
 
-        filtered = yield (filter_evts([event]))
+        filtered = await filter_evts([event])
         if not filtered:
             raise AuthError(403, "You don't have permission to access that event.")
 
-        results = yield self.store.get_events_around(
+        results = await self.store.get_events_around(
             room_id, event_id, before_limit, after_limit, event_filter
         )
 
-        results["events_before"] = yield filter_evts(results["events_before"])
-        results["events_after"] = yield filter_evts(results["events_after"])
-        results["event"] = event
+        if event_filter:
+            results["events_before"] = event_filter.filter(results["events_before"])
+            results["events_after"] = event_filter.filter(results["events_after"])
+
+        results["events_before"] = await filter_evts(results["events_before"])
+        results["events_after"] = await filter_evts(results["events_after"])
+        # filter_evts can return a pruned event in case the user is allowed to see that
+        # there's something there but not see the content, so use the event that's in
+        # `filtered` rather than the event we retrieved from the datastore.
+        results["event"] = filtered[0]
 
         if results["events_after"]:
             last_event_id = results["events_after"][-1].event_id
@@ -888,10 +994,15 @@ class RoomContextHandler(object):
         # first? Shouldn't we be consistent with /sync?
         # https://github.com/matrix-org/matrix-doc/issues/687
 
-        state = yield self.store.get_state_for_events(
+        state = await self.state_store.get_state_for_events(
             [last_event_id], state_filter=state_filter
         )
-        results["state"] = list(state[last_event_id].values())
+
+        state_events = list(state[last_event_id].values())
+        if event_filter:
+            state_events = event_filter.filter(state_events)
+
+        results["state"] = await filter_evts(state_events)
 
         # We use a dummy token here as we only care about the room portion of
         # the token, which we replace.
@@ -910,17 +1021,16 @@ class RoomEventSource(object):
     def __init__(self, hs):
         self.store = hs.get_datastore()
 
-    @defer.inlineCallbacks
-    def get_new_events(
+    async def get_new_events(
         self, user, from_key, limit, room_ids, is_guest, explicit_room_id=None
     ):
         # We just ignore the key for now.
 
-        to_key = yield self.get_current_key()
+        to_key = await self.get_current_key()
 
         from_token = RoomStreamToken.parse(from_key)
         if from_token.topological:
-            logger.warn("Stream has topological part!!!! %r", from_key)
+            logger.warning("Stream has topological part!!!! %r", from_key)
             from_key = "s%s" % (from_token.stream,)
 
         app_service = self.store.get_app_service_by_user_id(user.to_string())
@@ -929,11 +1039,11 @@ class RoomEventSource(object):
             # See https://github.com/matrix-org/matrix-doc/issues/1144
             raise NotImplementedError()
         else:
-            room_events = yield self.store.get_membership_changes_for_user(
+            room_events = await self.store.get_membership_changes_for_user(
                 user.to_string(), from_key, to_key
             )
 
-            room_to_events = yield self.store.get_room_events_stream_for_rooms(
+            room_to_events = await self.store.get_room_events_stream_for_rooms(
                 room_ids=room_ids,
                 from_key=from_key,
                 to_key=to_key,
@@ -961,15 +1071,3 @@ class RoomEventSource(object):
 
     def get_current_key_for_room(self, room_id):
         return self.store.get_room_events_max_id(room_id)
-
-    @defer.inlineCallbacks
-    def get_pagination_rows(self, user, config, key):
-        events, next_key = yield self.store.paginate_room_events(
-            room_id=key,
-            from_key=config.from_key,
-            to_key=config.to_key,
-            direction=config.direction,
-            limit=config.limit,
-        )
-
-        return (events, next_key)
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index a7e55f00e5..4cbc02b0d0 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -15,9 +15,9 @@
 
 import logging
 from collections import namedtuple
+from typing import Any, Dict, Optional
 
-from six import PY3, iteritems
-from six.moves import range
+from six import iteritems
 
 import msgpack
 from unpaddedbase64 import decode_base64, encode_base64
@@ -27,7 +27,6 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, JoinRules
 from synapse.api.errors import Codes, HttpResponseException
 from synapse.types import ThirdPartyInstanceID
-from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.caches.response_cache import ResponseCache
 
@@ -37,7 +36,6 @@ logger = logging.getLogger(__name__)
 
 REMOTE_ROOM_LIST_POLL_INTERVAL = 60 * 1000
 
-
 # This is used to indicate we should only return rooms published to the main list.
 EMPTY_THIRD_PARTY_ID = ThirdPartyInstanceID(None, None)
 
@@ -72,6 +70,8 @@ class RoomListHandler(BaseHandler):
                 This can be (None, None) to indicate the main list, or a particular
                 appservice and network id to use an appservice specific one.
                 Setting to None returns all public rooms across all lists.
+            from_federation (bool): true iff the request comes from the federation
+                API
         """
         if not self.enable_room_list_search:
             return defer.succeed({"chunk": [], "total_room_count_estimate": 0})
@@ -89,16 +89,12 @@ class RoomListHandler(BaseHandler):
             # appservice specific lists.
             logger.info("Bypassing cache as search request.")
 
-            # XXX: Quick hack to stop room directory queries taking too long.
-            # Timeout request after 60s. Probably want a more fundamental
-            # solution at some point
-            timeout = self.clock.time() + 60
             return self._get_public_room_list(
                 limit,
                 since_token,
                 search_filter,
                 network_tuple=network_tuple,
-                timeout=timeout,
+                from_federation=from_federation,
             )
 
         key = (limit, since_token, network_tuple)
@@ -114,258 +110,124 @@ class RoomListHandler(BaseHandler):
     @defer.inlineCallbacks
     def _get_public_room_list(
         self,
-        limit=None,
-        since_token=None,
-        search_filter=None,
-        network_tuple=EMPTY_THIRD_PARTY_ID,
-        from_federation=False,
-        timeout=None,
-    ):
+        limit: Optional[int] = None,
+        since_token: Optional[str] = None,
+        search_filter: Optional[Dict] = None,
+        network_tuple: ThirdPartyInstanceID = EMPTY_THIRD_PARTY_ID,
+        from_federation: bool = False,
+    ) -> Dict[str, Any]:
         """Generate a public room list.
         Args:
-            limit (int|None): Maximum amount of rooms to return.
-            since_token (str|None)
-            search_filter (dict|None): Dictionary to filter rooms by.
-            network_tuple (ThirdPartyInstanceID): Which public list to use.
+            limit: Maximum amount of rooms to return.
+            since_token:
+            search_filter: Dictionary to filter rooms by.
+            network_tuple: Which public list to use.
                 This can be (None, None) to indicate the main list, or a particular
                 appservice and network id to use an appservice specific one.
                 Setting to None returns all public rooms across all lists.
-            from_federation (bool): Whether this request originated from a
+            from_federation: Whether this request originated from a
                 federating server or a client. Used for room filtering.
-            timeout (int|None): Amount of seconds to wait for a response before
-                timing out.
         """
-        if since_token and since_token != "END":
-            since_token = RoomListNextBatch.from_token(since_token)
-        else:
-            since_token = None
 
-        rooms_to_order_value = {}
-        rooms_to_num_joined = {}
+        # Pagination tokens work by storing the room ID sent in the last batch,
+        # plus the direction (forwards or backwards). Next batch tokens always
+        # go forwards, prev batch tokens always go backwards.
 
-        newly_visible = []
-        newly_unpublished = []
         if since_token:
-            stream_token = since_token.stream_ordering
-            current_public_id = yield self.store.get_current_public_room_stream_id()
-            public_room_stream_id = since_token.public_room_stream_id
-            newly_visible, newly_unpublished = yield self.store.get_public_room_changes(
-                public_room_stream_id, current_public_id, network_tuple=network_tuple
-            )
-        else:
-            stream_token = yield self.store.get_room_max_stream_ordering()
-            public_room_stream_id = yield self.store.get_current_public_room_stream_id()
-
-        room_ids = yield self.store.get_public_room_ids_at_stream_id(
-            public_room_stream_id, network_tuple=network_tuple
-        )
-
-        # We want to return rooms in a particular order: the number of joined
-        # users. We then arbitrarily use the room_id as a tie breaker.
-
-        @defer.inlineCallbacks
-        def get_order_for_room(room_id):
-            # Most of the rooms won't have changed between the since token and
-            # now (especially if the since token is "now"). So, we can ask what
-            # the current users are in a room (that will hit a cache) and then
-            # check if the room has changed since the since token. (We have to
-            # do it in that order to avoid races).
-            # If things have changed then fall back to getting the current state
-            # at the since token.
-            joined_users = yield self.store.get_users_in_room(room_id)
-            if self.store.has_room_changed_since(room_id, stream_token):
-                latest_event_ids = yield self.store.get_forward_extremeties_for_room(
-                    room_id, stream_token
-                )
-
-                if not latest_event_ids:
-                    return
-
-                joined_users = yield self.state_handler.get_current_users_in_room(
-                    room_id, latest_event_ids
-                )
+            batch_token = RoomListNextBatch.from_token(since_token)
 
-            num_joined_users = len(joined_users)
-            rooms_to_num_joined[room_id] = num_joined_users
+            bounds = (batch_token.last_joined_members, batch_token.last_room_id)
+            forwards = batch_token.direction_is_forward
+        else:
+            batch_token = None
+            bounds = None
 
-            if num_joined_users == 0:
-                return
+            forwards = True
 
-            # We want larger rooms to be first, hence negating num_joined_users
-            rooms_to_order_value[room_id] = (-num_joined_users, room_id)
+        # we request one more than wanted to see if there are more pages to come
+        probing_limit = limit + 1 if limit is not None else None
 
-        logger.info(
-            "Getting ordering for %i rooms since %s", len(room_ids), stream_token
+        results = yield self.store.get_largest_public_rooms(
+            network_tuple,
+            search_filter,
+            probing_limit,
+            bounds=bounds,
+            forwards=forwards,
+            ignore_non_federatable=from_federation,
         )
-        yield concurrently_execute(get_order_for_room, room_ids, 10)
 
-        sorted_entries = sorted(rooms_to_order_value.items(), key=lambda e: e[1])
-        sorted_rooms = [room_id for room_id, _ in sorted_entries]
+        def build_room_entry(room):
+            entry = {
+                "room_id": room["room_id"],
+                "name": room["name"],
+                "topic": room["topic"],
+                "canonical_alias": room["canonical_alias"],
+                "num_joined_members": room["joined_members"],
+                "avatar_url": room["avatar"],
+                "world_readable": room["history_visibility"] == "world_readable",
+                "guest_can_join": room["guest_access"] == "can_join",
+            }
 
-        # `sorted_rooms` should now be a list of all public room ids that is
-        # stable across pagination. Therefore, we can use indices into this
-        # list as our pagination tokens.
+            # Filter out Nones – rather omit the field altogether
+            return {k: v for k, v in entry.items() if v is not None}
 
-        # Filter out rooms that we don't want to return
-        rooms_to_scan = [
-            r
-            for r in sorted_rooms
-            if r not in newly_unpublished and rooms_to_num_joined[r] > 0
-        ]
+        results = [build_room_entry(r) for r in results]
 
-        total_room_count = len(rooms_to_scan)
+        response = {}
+        num_results = len(results)
+        if limit is not None:
+            more_to_come = num_results == probing_limit
 
-        if since_token:
-            # Filter out rooms we've already returned previously
-            # `since_token.current_limit` is the index of the last room we
-            # sent down, so we exclude it and everything before/after it.
-            if since_token.direction_is_forward:
-                rooms_to_scan = rooms_to_scan[since_token.current_limit + 1 :]
+            # Depending on direction we trim either the front or back.
+            if forwards:
+                results = results[:limit]
             else:
-                rooms_to_scan = rooms_to_scan[: since_token.current_limit]
-                rooms_to_scan.reverse()
-
-        logger.info("After sorting and filtering, %i rooms remain", len(rooms_to_scan))
-
-        # _append_room_entry_to_chunk will append to chunk but will stop if
-        # len(chunk) > limit
-        #
-        # Normally we will generate enough results on the first iteration here,
-        #  but if there is a search filter, _append_room_entry_to_chunk may
-        # filter some results out, in which case we loop again.
-        #
-        # We don't want to scan over the entire range either as that
-        # would potentially waste a lot of work.
-        #
-        # XXX if there is no limit, we may end up DoSing the server with
-        # calls to get_current_state_ids for every single room on the
-        # server. Surely we should cap this somehow?
-        #
-        if limit:
-            step = limit + 1
+                results = results[-limit:]
         else:
-            # step cannot be zero
-            step = len(rooms_to_scan) if len(rooms_to_scan) != 0 else 1
-
-        chunk = []
-        for i in range(0, len(rooms_to_scan), step):
-            if timeout and self.clock.time() > timeout:
-                raise Exception("Timed out searching room directory")
-
-            batch = rooms_to_scan[i : i + step]
-            logger.info("Processing %i rooms for result", len(batch))
-            yield concurrently_execute(
-                lambda r: self._append_room_entry_to_chunk(
-                    r,
-                    rooms_to_num_joined[r],
-                    chunk,
-                    limit,
-                    search_filter,
-                    from_federation=from_federation,
-                ),
-                batch,
-                5,
-            )
-            logger.info("Now %i rooms in result", len(chunk))
-            if len(chunk) >= limit + 1:
-                break
-
-        chunk.sort(key=lambda e: (-e["num_joined_members"], e["room_id"]))
-
-        # Work out the new limit of the batch for pagination, or None if we
-        # know there are no more results that would be returned.
-        # i.e., [since_token.current_limit..new_limit] is the batch of rooms
-        # we've returned (or the reverse if we paginated backwards)
-        # We tried to pull out limit + 1 rooms above, so if we have <= limit
-        # then we know there are no more results to return
-        new_limit = None
-        if chunk and (not limit or len(chunk) > limit):
-
-            if not since_token or since_token.direction_is_forward:
-                if limit:
-                    chunk = chunk[:limit]
-                last_room_id = chunk[-1]["room_id"]
+            more_to_come = False
+
+        if num_results > 0:
+            final_entry = results[-1]
+            initial_entry = results[0]
+
+            if forwards:
+                if batch_token:
+                    # If there was a token given then we assume that there
+                    # must be previous results.
+                    response["prev_batch"] = RoomListNextBatch(
+                        last_joined_members=initial_entry["num_joined_members"],
+                        last_room_id=initial_entry["room_id"],
+                        direction_is_forward=False,
+                    ).to_token()
+
+                if more_to_come:
+                    response["next_batch"] = RoomListNextBatch(
+                        last_joined_members=final_entry["num_joined_members"],
+                        last_room_id=final_entry["room_id"],
+                        direction_is_forward=True,
+                    ).to_token()
             else:
-                if limit:
-                    chunk = chunk[-limit:]
-                last_room_id = chunk[0]["room_id"]
-
-            new_limit = sorted_rooms.index(last_room_id)
-
-        results = {"chunk": chunk, "total_room_count_estimate": total_room_count}
-
-        if since_token:
-            results["new_rooms"] = bool(newly_visible)
-
-        if not since_token or since_token.direction_is_forward:
-            if new_limit is not None:
-                results["next_batch"] = RoomListNextBatch(
-                    stream_ordering=stream_token,
-                    public_room_stream_id=public_room_stream_id,
-                    current_limit=new_limit,
-                    direction_is_forward=True,
-                ).to_token()
-
-            if since_token:
-                results["prev_batch"] = since_token.copy_and_replace(
-                    direction_is_forward=False,
-                    current_limit=since_token.current_limit + 1,
-                ).to_token()
-        else:
-            if new_limit is not None:
-                results["prev_batch"] = RoomListNextBatch(
-                    stream_ordering=stream_token,
-                    public_room_stream_id=public_room_stream_id,
-                    current_limit=new_limit,
-                    direction_is_forward=False,
-                ).to_token()
-
-            if since_token:
-                results["next_batch"] = since_token.copy_and_replace(
-                    direction_is_forward=True,
-                    current_limit=since_token.current_limit - 1,
-                ).to_token()
-
-        return results
-
-    @defer.inlineCallbacks
-    def _append_room_entry_to_chunk(
-        self,
-        room_id,
-        num_joined_users,
-        chunk,
-        limit,
-        search_filter,
-        from_federation=False,
-    ):
-        """Generate the entry for a room in the public room list and append it
-        to the `chunk` if it matches the search filter
-
-        Args:
-            room_id (str): The ID of the room.
-            num_joined_users (int): The number of joined users in the room.
-            chunk (list)
-            limit (int|None): Maximum amount of rooms to display. Function will
-                return if length of chunk is greater than limit + 1.
-            search_filter (dict|None)
-            from_federation (bool): Whether this request originated from a
-                federating server or a client. Used for room filtering.
-        """
-        if limit and len(chunk) > limit + 1:
-            # We've already got enough, so lets just drop it.
-            return
-
-        result = yield self.generate_room_entry(room_id, num_joined_users)
-        if not result:
-            return
-
-        if from_federation and not result.get("m.federate", True):
-            # This is a room that other servers cannot join. Do not show them
-            # this room.
-            return
+                if batch_token:
+                    response["next_batch"] = RoomListNextBatch(
+                        last_joined_members=final_entry["num_joined_members"],
+                        last_room_id=final_entry["room_id"],
+                        direction_is_forward=True,
+                    ).to_token()
+
+                if more_to_come:
+                    response["prev_batch"] = RoomListNextBatch(
+                        last_joined_members=initial_entry["num_joined_members"],
+                        last_room_id=initial_entry["room_id"],
+                        direction_is_forward=False,
+                    ).to_token()
+
+        response["chunk"] = results
+
+        response["total_room_count_estimate"] = yield self.store.count_public_rooms(
+            network_tuple, ignore_non_federatable=from_federation
+        )
 
-        if _matches_room_entry(result, search_filter):
-            chunk.append(result)
+        return response
 
     @cachedInlineCallbacks(num_args=1, cache_context=True)
     def generate_room_entry(
@@ -391,10 +253,21 @@ class RoomListHandler(BaseHandler):
         """
         result = {"room_id": room_id, "num_joined_members": num_joined_users}
 
+        if with_alias:
+            aliases = yield self.store.get_aliases_for_room(
+                room_id, on_invalidate=cache_context.invalidate
+            )
+            if aliases:
+                result["aliases"] = aliases
+
         current_state_ids = yield self.store.get_current_state_ids(
             room_id, on_invalidate=cache_context.invalidate
         )
 
+        if not current_state_ids:
+            # We're not in the room, so may as well bail out here.
+            return result
+
         event_map = yield self.store.get_events(
             [
                 event_id
@@ -427,14 +300,7 @@ class RoomListHandler(BaseHandler):
         create_event = current_state.get((EventTypes.Create, ""))
         result["m.federate"] = create_event.content.get("m.federate", True)
 
-        if with_alias:
-            aliases = yield self.store.get_aliases_for_room(
-                room_id, on_invalidate=cache_context.invalidate
-            )
-            if aliases:
-                result["aliases"] = aliases
-
-        name_event = yield current_state.get((EventTypes.Name, ""))
+        name_event = current_state.get((EventTypes.Name, ""))
         if name_event:
             name = name_event.content.get("name", None)
             if name:
@@ -580,18 +446,15 @@ class RoomListNextBatch(
     namedtuple(
         "RoomListNextBatch",
         (
-            "stream_ordering",  # stream_ordering of the first public room list
-            "public_room_stream_id",  # public room stream id for first public room list
-            "current_limit",  # The number of previous rooms returned
+            "last_joined_members",  # The count to get rooms after/before
+            "last_room_id",  # The room_id to get rooms after/before
             "direction_is_forward",  # Bool if this is a next_batch, false if prev_batch
         ),
     )
 ):
-
     KEY_DICT = {
-        "stream_ordering": "s",
-        "public_room_stream_id": "p",
-        "current_limit": "n",
+        "last_joined_members": "m",
+        "last_room_id": "r",
         "direction_is_forward": "d",
     }
 
@@ -599,13 +462,7 @@ class RoomListNextBatch(
 
     @classmethod
     def from_token(cls, token):
-        if PY3:
-            # The argument raw=False is only available on new versions of
-            # msgpack, and only really needed on Python 3. Gate it behind
-            # a PY3 check to avoid causing issues on Debian-packaged versions.
-            decoded = msgpack.loads(decode_base64(token), raw=False)
-        else:
-            decoded = msgpack.loads(decode_base64(token))
+        decoded = msgpack.loads(decode_base64(token), raw=False)
         return RoomListNextBatch(
             **{cls.REVERSE_KEY_DICT[key]: val for key, val in decoded.items()}
         )
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 35450feb6f..0f7af982f0 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -17,30 +17,26 @@
 
 import abc
 import logging
+from typing import Dict, Iterable, List, Optional, Tuple
 
 from six.moves import http_client
 
-from signedjson.key import decode_verify_key_bytes
-from signedjson.sign import verify_signed_json
-from unpaddedbase64 import decode_base64
-
-from twisted.internet import defer
-
 from synapse import types
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import AuthError, Codes, HttpResponseException, SynapseError
-from synapse.handlers.identity import LookupAlgorithm, create_id_access_token_header
-from synapse.types import RoomID, UserID
+from synapse.api.errors import AuthError, Codes, SynapseError
+from synapse.events import EventBase
+from synapse.events.snapshot import EventContext
+from synapse.replication.http.membership import (
+    ReplicationLocallyRejectInviteRestServlet,
+)
+from synapse.types import Collection, Requester, RoomAlias, RoomID, UserID
 from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room, user_left_room
-from synapse.util.hash import sha256_and_url_safe_base64
 
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
-id_server_scheme = "https://"
-
 
 class RoomMemberHandler(object):
     # TODO(paul): This handler currently contains a messy conflation of
@@ -51,20 +47,15 @@ class RoomMemberHandler(object):
     __metaclass__ = abc.ABCMeta
 
     def __init__(self, hs):
-        """
-
-        Args:
-            hs (synapse.server.HomeServer):
-        """
         self.hs = hs
         self.store = hs.get_datastore()
         self.auth = hs.get_auth()
         self.state_handler = hs.get_state_handler()
         self.config = hs.config
-        self.simple_http_client = hs.get_simple_http_client()
 
         self.federation_handler = hs.get_handlers().federation_handler
         self.directory_handler = hs.get_handlers().directory_handler
+        self.identity_handler = hs.get_handlers().identity_handler
         self.registration_handler = hs.get_registration_handler()
         self.profile_handler = hs.get_profile_handler()
         self.event_creation_handler = hs.get_event_creation_handler()
@@ -78,88 +69,117 @@ class RoomMemberHandler(object):
         self._enable_lookup = hs.config.enable_3pid_lookup
         self.allow_per_room_profiles = self.config.allow_per_room_profiles
 
+        self._event_stream_writer_instance = hs.config.worker.writers.events
+        self._is_on_event_persistence_instance = (
+            self._event_stream_writer_instance == hs.get_instance_name()
+        )
+        if self._is_on_event_persistence_instance:
+            self.persist_event_storage = hs.get_storage().persistence
+        else:
+            self._locally_reject_client = ReplicationLocallyRejectInviteRestServlet.make_client(
+                hs
+            )
+
         # This is only used to get at ratelimit function, and
         # maybe_kick_guest_users. It's fine there are multiple of these as
         # it doesn't store state.
         self.base_handler = BaseHandler(hs)
 
     @abc.abstractmethod
-    def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
+    async def _remote_join(
+        self,
+        requester: Requester,
+        remote_room_hosts: List[str],
+        room_id: str,
+        user: UserID,
+        content: dict,
+    ) -> Tuple[str, int]:
         """Try and join a room that this server is not in
 
         Args:
-            requester (Requester)
-            remote_room_hosts (list[str]): List of servers that can be used
-                to join via.
-            room_id (str): Room that we are trying to join
-            user (UserID): User who is trying to join
-            content (dict): A dict that should be used as the content of the
-                join event.
-
-        Returns:
-            Deferred
+            requester
+            remote_room_hosts: List of servers that can be used to join via.
+            room_id: Room that we are trying to join
+            user: User who is trying to join
+            content: A dict that should be used as the content of the join event.
         """
         raise NotImplementedError()
 
     @abc.abstractmethod
-    def _remote_reject_invite(self, requester, remote_room_hosts, room_id, target):
+    async def _remote_reject_invite(
+        self,
+        requester: Requester,
+        remote_room_hosts: List[str],
+        room_id: str,
+        target: UserID,
+        content: dict,
+    ) -> Tuple[Optional[str], int]:
         """Attempt to reject an invite for a room this server is not in. If we
         fail to do so we locally mark the invite as rejected.
 
         Args:
-            requester (Requester)
-            remote_room_hosts (list[str]): List of servers to use to try and
-                reject invite
-            room_id (str)
-            target (UserID): The user rejecting the invite
+            requester
+            remote_room_hosts: List of servers to use to try and reject invite
+            room_id
+            target: The user rejecting the invite
+            content: The content for the rejection event
 
         Returns:
-            Deferred[dict]: A dictionary to be returned to the client, may
+            A dictionary to be returned to the client, may
             include event_id etc, or nothing if we locally rejected
         """
         raise NotImplementedError()
 
+    async def locally_reject_invite(self, user_id: str, room_id: str) -> int:
+        """Mark the invite has having been rejected even though we failed to
+        create a leave event for it.
+        """
+        if self._is_on_event_persistence_instance:
+            return await self.persist_event_storage.locally_reject_invite(
+                user_id, room_id
+            )
+        else:
+            result = await self._locally_reject_client(
+                instance_name=self._event_stream_writer_instance,
+                user_id=user_id,
+                room_id=room_id,
+            )
+            return result["stream_id"]
+
     @abc.abstractmethod
-    def _user_joined_room(self, target, room_id):
+    async def _user_joined_room(self, target: UserID, room_id: str) -> None:
         """Notifies distributor on master process that the user has joined the
         room.
 
         Args:
-            target (UserID)
-            room_id (str)
-
-        Returns:
-            Deferred|None
+            target
+            room_id
         """
         raise NotImplementedError()
 
     @abc.abstractmethod
-    def _user_left_room(self, target, room_id):
+    async def _user_left_room(self, target: UserID, room_id: str) -> None:
         """Notifies distributor on master process that the user has left the
         room.
 
         Args:
-            target (UserID)
-            room_id (str)
-
-        Returns:
-            Deferred|None
+            target
+            room_id
         """
         raise NotImplementedError()
 
-    @defer.inlineCallbacks
-    def _local_membership_update(
+    async def _local_membership_update(
         self,
-        requester,
-        target,
-        room_id,
-        membership,
-        prev_events_and_hashes,
-        txn_id=None,
-        ratelimit=True,
-        content=None,
-        require_consent=True,
-    ):
+        requester: Requester,
+        target: UserID,
+        room_id: str,
+        membership: str,
+        prev_event_ids: Collection[str],
+        txn_id: Optional[str] = None,
+        ratelimit: bool = True,
+        content: Optional[dict] = None,
+        require_consent: bool = True,
+    ) -> Tuple[str, int]:
         user_id = target.to_string()
 
         if content is None:
@@ -169,7 +189,7 @@ class RoomMemberHandler(object):
         if requester.is_guest:
             content["kind"] = "guest"
 
-        event, context = yield self.event_creation_handler.create_event(
+        event, context = await self.event_creation_handler.create_event(
             requester,
             {
                 "type": EventTypes.Member,
@@ -182,23 +202,24 @@ class RoomMemberHandler(object):
             },
             token_id=requester.access_token_id,
             txn_id=txn_id,
-            prev_events_and_hashes=prev_events_and_hashes,
+            prev_event_ids=prev_event_ids,
             require_consent=require_consent,
         )
 
         # Check if this event matches the previous membership event for the user.
-        duplicate = yield self.event_creation_handler.deduplicate_state_event(
+        duplicate = await self.event_creation_handler.deduplicate_state_event(
             event, context
         )
         if duplicate is not None:
             # Discard the new event since this membership change is a no-op.
-            return duplicate
+            _, stream_id = await self.store.get_event_ordering(duplicate.event_id)
+            return duplicate.event_id, stream_id
 
-        yield self.event_creation_handler.handle_new_client_event(
+        stream_id = await self.event_creation_handler.handle_new_client_event(
             requester, event, context, extra_users=[target], ratelimit=ratelimit
         )
 
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = await context.get_prev_state_ids()
 
         prev_member_event_id = prev_state_ids.get((EventTypes.Member, user_id), None)
 
@@ -208,48 +229,30 @@ class RoomMemberHandler(object):
             # info.
             newly_joined = True
             if prev_member_event_id:
-                prev_member_event = yield self.store.get_event(prev_member_event_id)
+                prev_member_event = await self.store.get_event(prev_member_event_id)
                 newly_joined = prev_member_event.membership != Membership.JOIN
             if newly_joined:
-                yield self._user_joined_room(target, room_id)
-
-            # Copy over direct message status and room tags if this is a join
-            # on an upgraded room
-
-            # Check if this is an upgraded room
-            predecessor = yield self.store.get_room_predecessor(room_id)
-
-            if predecessor:
-                # It is an upgraded room. Copy over old tags
-                self.copy_room_tags_and_direct_to_room(
-                    predecessor["room_id"], room_id, user_id
-                )
-                # Move over old push rules
-                self.store.move_push_rules_from_room_to_room_for_user(
-                    predecessor["room_id"], room_id, user_id
-                )
+                await self._user_joined_room(target, room_id)
         elif event.membership == Membership.LEAVE:
             if prev_member_event_id:
-                prev_member_event = yield self.store.get_event(prev_member_event_id)
+                prev_member_event = await self.store.get_event(prev_member_event_id)
                 if prev_member_event.membership == Membership.JOIN:
-                    yield self._user_left_room(target, room_id)
+                    await self._user_left_room(target, room_id)
 
-        return event
+        return event.event_id, stream_id
 
-    @defer.inlineCallbacks
-    def copy_room_tags_and_direct_to_room(self, old_room_id, new_room_id, user_id):
+    async def copy_room_tags_and_direct_to_room(
+        self, old_room_id, new_room_id, user_id
+    ) -> None:
         """Copies the tags and direct room state from one room to another.
 
         Args:
-            old_room_id (str)
-            new_room_id (str)
-            user_id (str)
-
-        Returns:
-            Deferred[None]
+            old_room_id: The room ID of the old room.
+            new_room_id: The room ID of the new room.
+            user_id: The user's ID.
         """
         # Retrieve user account data for predecessor room
-        user_account_data, _ = yield self.store.get_account_data_for_user(user_id)
+        user_account_data, _ = await self.store.get_account_data_for_user(user_id)
 
         # Copy direct message state if applicable
         direct_rooms = user_account_data.get("m.direct", {})
@@ -262,36 +265,35 @@ class RoomMemberHandler(object):
                     direct_rooms[key].append(new_room_id)
 
                     # Save back to user's m.direct account data
-                    yield self.store.add_account_data_for_user(
+                    await self.store.add_account_data_for_user(
                         user_id, "m.direct", direct_rooms
                     )
                     break
 
         # Copy room tags if applicable
-        room_tags = yield self.store.get_tags_for_room(user_id, old_room_id)
+        room_tags = await self.store.get_tags_for_room(user_id, old_room_id)
 
         # Copy each room tag to the new room
         for tag, tag_content in room_tags.items():
-            yield self.store.add_tag_to_room(user_id, new_room_id, tag, tag_content)
+            await self.store.add_tag_to_room(user_id, new_room_id, tag, tag_content)
 
-    @defer.inlineCallbacks
-    def update_membership(
+    async def update_membership(
         self,
-        requester,
-        target,
-        room_id,
-        action,
-        txn_id=None,
-        remote_room_hosts=None,
-        third_party_signed=None,
-        ratelimit=True,
-        content=None,
-        require_consent=True,
-    ):
+        requester: Requester,
+        target: UserID,
+        room_id: str,
+        action: str,
+        txn_id: Optional[str] = None,
+        remote_room_hosts: Optional[List[str]] = None,
+        third_party_signed: Optional[dict] = None,
+        ratelimit: bool = True,
+        content: Optional[dict] = None,
+        require_consent: bool = True,
+    ) -> Tuple[Optional[str], int]:
         key = (room_id,)
 
-        with (yield self.member_linearizer.queue(key)):
-            result = yield self._update_membership(
+        with (await self.member_linearizer.queue(key)):
+            result = await self._update_membership(
                 requester,
                 target,
                 room_id,
@@ -306,20 +308,19 @@ class RoomMemberHandler(object):
 
         return result
 
-    @defer.inlineCallbacks
-    def _update_membership(
+    async def _update_membership(
         self,
-        requester,
-        target,
-        room_id,
-        action,
-        txn_id=None,
-        remote_room_hosts=None,
-        third_party_signed=None,
-        ratelimit=True,
-        content=None,
-        require_consent=True,
-    ):
+        requester: Requester,
+        target: UserID,
+        room_id: str,
+        action: str,
+        txn_id: Optional[str] = None,
+        remote_room_hosts: Optional[List[str]] = None,
+        third_party_signed: Optional[dict] = None,
+        ratelimit: bool = True,
+        content: Optional[dict] = None,
+        require_consent: bool = True,
+    ) -> Tuple[Optional[str], int]:
         content_specified = bool(content)
         if content is None:
             content = {}
@@ -342,7 +343,7 @@ class RoomMemberHandler(object):
         # if this is a join with a 3pid signature, we may need to turn a 3pid
         # invite into a normal invite before we can handle the join.
         if third_party_signed is not None:
-            yield self.federation_handler.exchange_third_party_invite(
+            await self.federation_handler.exchange_third_party_invite(
                 third_party_signed["sender"],
                 target.to_string(),
                 room_id,
@@ -353,7 +354,7 @@ class RoomMemberHandler(object):
             remote_room_hosts = []
 
         if effective_membership_state not in ("leave", "ban"):
-            is_blocked = yield self.store.is_room_blocked(room_id)
+            is_blocked = await self.store.is_room_blocked(room_id)
             if is_blocked:
                 raise SynapseError(403, "This room has been blocked on this server")
 
@@ -372,7 +373,7 @@ class RoomMemberHandler(object):
                 is_requester_admin = True
 
             else:
-                is_requester_admin = yield self.auth.is_server_admin(requester.user)
+                is_requester_admin = await self.auth.is_server_admin(requester.user)
 
             if not is_requester_admin:
                 if self.config.block_non_admin_invites:
@@ -391,10 +392,9 @@ class RoomMemberHandler(object):
             if block_invite:
                 raise SynapseError(403, "Invites have been disabled on this server")
 
-        prev_events_and_hashes = yield self.store.get_prev_events_for_room(room_id)
-        latest_event_ids = (event_id for (event_id, _, _) in prev_events_and_hashes)
+        latest_event_ids = await self.store.get_prev_events_for_room(room_id)
 
-        current_state_ids = yield self.state_handler.get_current_state_ids(
+        current_state_ids = await self.state_handler.get_current_state_ids(
             room_id, latest_event_ids=latest_event_ids
         )
 
@@ -403,7 +403,7 @@ class RoomMemberHandler(object):
         # transitions and generic otherwise
         old_state_id = current_state_ids.get((EventTypes.Member, target.to_string()))
         if old_state_id:
-            old_state = yield self.store.get_event(old_state_id, allow_none=True)
+            old_state = await self.store.get_event(old_state_id, allow_none=True)
             old_membership = old_state.content.get("membership") if old_state else None
             if action == "unban" and old_membership != "ban":
                 raise SynapseError(
@@ -424,7 +424,13 @@ class RoomMemberHandler(object):
                 same_membership = old_membership == effective_membership_state
                 same_sender = requester.user.to_string() == old_state.sender
                 if same_sender and same_membership and same_content:
-                    return old_state
+                    _, stream_id = await self.store.get_event_ordering(
+                        old_state.event_id
+                    )
+                    return (
+                        old_state.event_id,
+                        stream_id,
+                    )
 
             if old_membership in ["ban", "leave"] and action == "kick":
                 raise AuthError(403, "The target user is not in the room")
@@ -435,7 +441,7 @@ class RoomMemberHandler(object):
                 old_membership == Membership.INVITE
                 and effective_membership_state == Membership.LEAVE
             ):
-                is_blocked = yield self._is_server_notice_room(room_id)
+                is_blocked = await self._is_server_notice_room(room_id)
                 if is_blocked:
                     raise SynapseError(
                         http_client.FORBIDDEN,
@@ -446,18 +452,18 @@ class RoomMemberHandler(object):
             if action == "kick":
                 raise AuthError(403, "The target user is not in the room")
 
-        is_host_in_room = yield self._is_host_in_room(current_state_ids)
+        is_host_in_room = await self._is_host_in_room(current_state_ids)
 
         if effective_membership_state == Membership.JOIN:
             if requester.is_guest:
-                guest_can_join = yield self._can_guest_join(current_state_ids)
+                guest_can_join = await self._can_guest_join(current_state_ids)
                 if not guest_can_join:
                     # This should be an auth check, but guests are a local concept,
                     # so don't really fit into the general auth process.
                     raise AuthError(403, "Guest access not allowed")
 
             if not is_host_in_room:
-                inviter = yield self._get_inviter(target.to_string(), room_id)
+                inviter = await self._get_inviter(target.to_string(), room_id)
                 if inviter and not self.hs.is_mine(inviter):
                     remote_room_hosts.append(inviter.domain)
 
@@ -465,21 +471,22 @@ class RoomMemberHandler(object):
 
                 profile = self.profile_handler
                 if not content_specified:
-                    content["displayname"] = yield profile.get_displayname(target)
-                    content["avatar_url"] = yield profile.get_avatar_url(target)
+                    content["displayname"] = await profile.get_displayname(target)
+                    content["avatar_url"] = await profile.get_avatar_url(target)
 
                 if requester.is_guest:
                     content["kind"] = "guest"
 
-                ret = yield self._remote_join(
+                remote_join_response = await self._remote_join(
                     requester, remote_room_hosts, room_id, target, content
                 )
-                return ret
+
+                return remote_join_response
 
         elif effective_membership_state == Membership.LEAVE:
             if not is_host_in_room:
                 # perhaps we've been invited
-                inviter = yield self._get_inviter(target.to_string(), room_id)
+                inviter = await self._get_inviter(target.to_string(), room_id)
                 if not inviter:
                     raise SynapseError(404, "Not a known room")
 
@@ -493,36 +500,116 @@ class RoomMemberHandler(object):
                 else:
                     # send the rejection to the inviter's HS.
                     remote_room_hosts = remote_room_hosts + [inviter.domain]
-                    res = yield self._remote_reject_invite(
-                        requester, remote_room_hosts, room_id, target
+                    return await self._remote_reject_invite(
+                        requester, remote_room_hosts, room_id, target, content,
                     )
-                    return res
 
-        res = yield self._local_membership_update(
+        return await self._local_membership_update(
             requester=requester,
             target=target,
             room_id=room_id,
             membership=effective_membership_state,
             txn_id=txn_id,
             ratelimit=ratelimit,
-            prev_events_and_hashes=prev_events_and_hashes,
+            prev_event_ids=latest_event_ids,
             content=content,
             require_consent=require_consent,
         )
-        return res
 
-    @defer.inlineCallbacks
-    def send_membership_event(self, requester, event, context, ratelimit=True):
+    async def transfer_room_state_on_room_upgrade(
+        self, old_room_id: str, room_id: str
+    ) -> None:
+        """Upon our server becoming aware of an upgraded room, either by upgrading a room
+        ourselves or joining one, we can transfer over information from the previous room.
+
+        Copies user state (tags/push rules) for every local user that was in the old room, as
+        well as migrating the room directory state.
+
+        Args:
+            old_room_id: The ID of the old room
+            room_id: The ID of the new room
+        """
+        logger.info("Transferring room state from %s to %s", old_room_id, room_id)
+
+        # Find all local users that were in the old room and copy over each user's state
+        users = await self.store.get_users_in_room(old_room_id)
+        await self.copy_user_state_on_room_upgrade(old_room_id, room_id, users)
+
+        # Add new room to the room directory if the old room was there
+        # Remove old room from the room directory
+        old_room = await self.store.get_room(old_room_id)
+        if old_room and old_room["is_public"]:
+            await self.store.set_room_is_public(old_room_id, False)
+            await self.store.set_room_is_public(room_id, True)
+
+        # Transfer alias mappings in the room directory
+        await self.store.update_aliases_for_room(old_room_id, room_id)
+
+        # Check if any groups we own contain the predecessor room
+        local_group_ids = await self.store.get_local_groups_for_room(old_room_id)
+        for group_id in local_group_ids:
+            # Add new the new room to those groups
+            await self.store.add_room_to_group(group_id, room_id, old_room["is_public"])
+
+            # Remove the old room from those groups
+            await self.store.remove_room_from_group(group_id, old_room_id)
+
+    async def copy_user_state_on_room_upgrade(
+        self, old_room_id: str, new_room_id: str, user_ids: Iterable[str]
+    ) -> None:
+        """Copy user-specific information when they join a new room when that new room is the
+        result of a room upgrade
+
+        Args:
+            old_room_id: The ID of upgraded room
+            new_room_id: The ID of the new room
+            user_ids: User IDs to copy state for
+        """
+
+        logger.debug(
+            "Copying over room tags and push rules from %s to %s for users %s",
+            old_room_id,
+            new_room_id,
+            user_ids,
+        )
+
+        for user_id in user_ids:
+            try:
+                # It is an upgraded room. Copy over old tags
+                await self.copy_room_tags_and_direct_to_room(
+                    old_room_id, new_room_id, user_id
+                )
+                # Copy over push rules
+                await self.store.copy_push_rules_from_room_to_room_for_user(
+                    old_room_id, new_room_id, user_id
+                )
+            except Exception:
+                logger.exception(
+                    "Error copying tags and/or push rules from rooms %s to %s for user %s. "
+                    "Skipping...",
+                    old_room_id,
+                    new_room_id,
+                    user_id,
+                )
+                continue
+
+    async def send_membership_event(
+        self,
+        requester: Requester,
+        event: EventBase,
+        context: EventContext,
+        ratelimit: bool = True,
+    ):
         """
         Change the membership status of a user in a room.
 
         Args:
-            requester (Requester): The local user who requested the membership
+            requester: The local user who requested the membership
                 event. If None, certain checks, like whether this homeserver can
                 act as the sender, will be skipped.
-            event (SynapseEvent): The membership event.
+            event: The membership event.
             context: The context of the event.
-            ratelimit (bool): Whether to rate limit this request.
+            ratelimit: Whether to rate limit this request.
         Raises:
             SynapseError if there was a problem changing the membership.
         """
@@ -538,27 +625,27 @@ class RoomMemberHandler(object):
         else:
             requester = types.create_requester(target_user)
 
-        prev_event = yield self.event_creation_handler.deduplicate_state_event(
+        prev_event = await self.event_creation_handler.deduplicate_state_event(
             event, context
         )
         if prev_event is not None:
             return
 
-        prev_state_ids = yield context.get_prev_state_ids(self.store)
+        prev_state_ids = await context.get_prev_state_ids()
         if event.membership == Membership.JOIN:
             if requester.is_guest:
-                guest_can_join = yield self._can_guest_join(prev_state_ids)
+                guest_can_join = await self._can_guest_join(prev_state_ids)
                 if not guest_can_join:
                     # This should be an auth check, but guests are a local concept,
                     # so don't really fit into the general auth process.
                     raise AuthError(403, "Guest access not allowed")
 
         if event.membership not in (Membership.LEAVE, Membership.BAN):
-            is_blocked = yield self.store.is_room_blocked(room_id)
+            is_blocked = await self.store.is_room_blocked(room_id)
             if is_blocked:
                 raise SynapseError(403, "This room has been blocked on this server")
 
-        yield self.event_creation_handler.handle_new_client_event(
+        await self.event_creation_handler.handle_new_client_event(
             requester, event, context, extra_users=[target_user], ratelimit=ratelimit
         )
 
@@ -572,18 +659,19 @@ class RoomMemberHandler(object):
             # info.
             newly_joined = True
             if prev_member_event_id:
-                prev_member_event = yield self.store.get_event(prev_member_event_id)
+                prev_member_event = await self.store.get_event(prev_member_event_id)
                 newly_joined = prev_member_event.membership != Membership.JOIN
             if newly_joined:
-                yield self._user_joined_room(target_user, room_id)
+                await self._user_joined_room(target_user, room_id)
         elif event.membership == Membership.LEAVE:
             if prev_member_event_id:
-                prev_member_event = yield self.store.get_event(prev_member_event_id)
+                prev_member_event = await self.store.get_event(prev_member_event_id)
                 if prev_member_event.membership == Membership.JOIN:
-                    yield self._user_left_room(target_user, room_id)
+                    await self._user_left_room(target_user, room_id)
 
-    @defer.inlineCallbacks
-    def _can_guest_join(self, current_state_ids):
+    async def _can_guest_join(
+        self, current_state_ids: Dict[Tuple[str, str], str]
+    ) -> bool:
         """
         Returns whether a guest can join a room based on its current state.
         """
@@ -591,7 +679,7 @@ class RoomMemberHandler(object):
         if not guest_access_id:
             return False
 
-        guest_access = yield self.store.get_event(guest_access_id)
+        guest_access = await self.store.get_event(guest_access_id)
 
         return (
             guest_access
@@ -600,13 +688,14 @@ class RoomMemberHandler(object):
             and guest_access.content["guest_access"] == "can_join"
         )
 
-    @defer.inlineCallbacks
-    def lookup_room_alias(self, room_alias):
+    async def lookup_room_alias(
+        self, room_alias: RoomAlias
+    ) -> Tuple[RoomID, List[str]]:
         """
         Get the room ID associated with a room alias.
 
         Args:
-            room_alias (RoomAlias): The alias to look up.
+            room_alias: The alias to look up.
         Returns:
             A tuple of:
                 The room ID as a RoomID object.
@@ -615,7 +704,7 @@ class RoomMemberHandler(object):
             SynapseError if room alias could not be found.
         """
         directory_handler = self.directory_handler
-        mapping = yield directory_handler.get_association(room_alias)
+        mapping = await directory_handler.get_association(room_alias)
 
         if not mapping:
             raise SynapseError(404, "No such room alias")
@@ -630,28 +719,27 @@ class RoomMemberHandler(object):
 
         return RoomID.from_string(room_id), servers
 
-    @defer.inlineCallbacks
-    def _get_inviter(self, user_id, room_id):
-        invite = yield self.store.get_invite_for_user_in_room(
+    async def _get_inviter(self, user_id: str, room_id: str) -> Optional[UserID]:
+        invite = await self.store.get_invite_for_local_user_in_room(
             user_id=user_id, room_id=room_id
         )
         if invite:
             return UserID.from_string(invite.sender)
+        return None
 
-    @defer.inlineCallbacks
-    def do_3pid_invite(
+    async def do_3pid_invite(
         self,
-        room_id,
-        inviter,
-        medium,
-        address,
-        id_server,
-        requester,
-        txn_id,
-        id_access_token=None,
-    ):
+        room_id: str,
+        inviter: UserID,
+        medium: str,
+        address: str,
+        id_server: str,
+        requester: Requester,
+        txn_id: Optional[str],
+        id_access_token: Optional[str] = None,
+    ) -> int:
         if self.config.block_non_admin_invites:
-            is_requester_admin = yield self.auth.is_server_admin(requester.user)
+            is_requester_admin = await self.auth.is_server_admin(requester.user)
             if not is_requester_admin:
                 raise SynapseError(
                     403, "Invites have been disabled on this server", Codes.FORBIDDEN
@@ -659,9 +747,9 @@ class RoomMemberHandler(object):
 
         # We need to rate limit *before* we send out any 3PID invites, so we
         # can't just rely on the standard ratelimiting of events.
-        yield self.base_handler.ratelimit(requester)
+        await self.base_handler.ratelimit(requester)
 
-        can_invite = yield self.third_party_event_rules.check_threepid_can_be_invited(
+        can_invite = await self.third_party_event_rules.check_threepid_can_be_invited(
             medium, address, room_id
         )
         if not can_invite:
@@ -676,14 +764,16 @@ class RoomMemberHandler(object):
                 403, "Looking up third-party identifiers is denied from this server"
             )
 
-        invitee = yield self._lookup_3pid(id_server, medium, address, id_access_token)
+        invitee = await self.identity_handler.lookup_3pid(
+            id_server, medium, address, id_access_token
+        )
 
         if invitee:
-            yield self.update_membership(
+            _, stream_id = await self.update_membership(
                 requester, UserID.from_string(invitee), room_id, "invite", txn_id=txn_id
             )
         else:
-            yield self._make_and_store_3pid_invite(
+            stream_id = await self._make_and_store_3pid_invite(
                 requester,
                 id_server,
                 medium,
@@ -694,215 +784,20 @@ class RoomMemberHandler(object):
                 id_access_token=id_access_token,
             )
 
-    @defer.inlineCallbacks
-    def _lookup_3pid(self, id_server, medium, address, id_access_token=None):
-        """Looks up a 3pid in the passed identity server.
-
-        Args:
-            id_server (str): The server name (including port, if required)
-                of the identity server to use.
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-            id_access_token (str|None): The access token to authenticate to the identity
-                server with
-
-        Returns:
-            str|None: the matrix ID of the 3pid, or None if it is not recognized.
-        """
-        if id_access_token is not None:
-            try:
-                results = yield self._lookup_3pid_v2(
-                    id_server, id_access_token, medium, address
-                )
-                return results
-
-            except Exception as e:
-                # Catch HttpResponseExcept for a non-200 response code
-                # Check if this identity server does not know about v2 lookups
-                if isinstance(e, HttpResponseException) and e.code == 404:
-                    # This is an old identity server that does not yet support v2 lookups
-                    logger.warning(
-                        "Attempted v2 lookup on v1 identity server %s. Falling "
-                        "back to v1",
-                        id_server,
-                    )
-                else:
-                    logger.warning("Error when looking up hashing details: %s", e)
-                    return None
-
-        return (yield self._lookup_3pid_v1(id_server, medium, address))
-
-    @defer.inlineCallbacks
-    def _lookup_3pid_v1(self, id_server, medium, address):
-        """Looks up a 3pid in the passed identity server using v1 lookup.
-
-        Args:
-            id_server (str): The server name (including port, if required)
-                of the identity server to use.
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-
-        Returns:
-            str: the matrix ID of the 3pid, or None if it is not recognized.
-        """
-        try:
-            data = yield self.simple_http_client.get_json(
-                "%s%s/_matrix/identity/api/v1/lookup" % (id_server_scheme, id_server),
-                {"medium": medium, "address": address},
-            )
-
-            if "mxid" in data:
-                if "signatures" not in data:
-                    raise AuthError(401, "No signatures on 3pid binding")
-                yield self._verify_any_signature(data, id_server)
-                return data["mxid"]
-
-        except IOError as e:
-            logger.warning("Error from v1 identity server lookup: %s" % (e,))
-
-        return None
-
-    @defer.inlineCallbacks
-    def _lookup_3pid_v2(self, id_server, id_access_token, medium, address):
-        """Looks up a 3pid in the passed identity server using v2 lookup.
-
-        Args:
-            id_server (str): The server name (including port, if required)
-                of the identity server to use.
-            id_access_token (str): The access token to authenticate to the identity server with
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-
-        Returns:
-            Deferred[str|None]: the matrix ID of the 3pid, or None if it is not recognised.
-        """
-        # Check what hashing details are supported by this identity server
-        hash_details = yield self.simple_http_client.get_json(
-            "%s%s/_matrix/identity/v2/hash_details" % (id_server_scheme, id_server),
-            {"access_token": id_access_token},
-        )
-
-        if not isinstance(hash_details, dict):
-            logger.warning(
-                "Got non-dict object when checking hash details of %s%s: %s",
-                id_server_scheme,
-                id_server,
-                hash_details,
-            )
-            raise SynapseError(
-                400,
-                "Non-dict object from %s%s during v2 hash_details request: %s"
-                % (id_server_scheme, id_server, hash_details),
-            )
-
-        # Extract information from hash_details
-        supported_lookup_algorithms = hash_details.get("algorithms")
-        lookup_pepper = hash_details.get("lookup_pepper")
-        if (
-            not supported_lookup_algorithms
-            or not isinstance(supported_lookup_algorithms, list)
-            or not lookup_pepper
-            or not isinstance(lookup_pepper, str)
-        ):
-            raise SynapseError(
-                400,
-                "Invalid hash details received from identity server %s%s: %s"
-                % (id_server_scheme, id_server, hash_details),
-            )
-
-        # Check if any of the supported lookup algorithms are present
-        if LookupAlgorithm.SHA256 in supported_lookup_algorithms:
-            # Perform a hashed lookup
-            lookup_algorithm = LookupAlgorithm.SHA256
-
-            # Hash address, medium and the pepper with sha256
-            to_hash = "%s %s %s" % (address, medium, lookup_pepper)
-            lookup_value = sha256_and_url_safe_base64(to_hash)
-
-        elif LookupAlgorithm.NONE in supported_lookup_algorithms:
-            # Perform a non-hashed lookup
-            lookup_algorithm = LookupAlgorithm.NONE
-
-            # Combine together plaintext address and medium
-            lookup_value = "%s %s" % (address, medium)
-
-        else:
-            logger.warning(
-                "None of the provided lookup algorithms of %s are supported: %s",
-                id_server,
-                supported_lookup_algorithms,
-            )
-            raise SynapseError(
-                400,
-                "Provided identity server does not support any v2 lookup "
-                "algorithms that this homeserver supports.",
-            )
-
-        # Authenticate with identity server given the access token from the client
-        headers = {"Authorization": create_id_access_token_header(id_access_token)}
-
-        try:
-            lookup_results = yield self.simple_http_client.post_json_get_json(
-                "%s%s/_matrix/identity/v2/lookup" % (id_server_scheme, id_server),
-                {
-                    "addresses": [lookup_value],
-                    "algorithm": lookup_algorithm,
-                    "pepper": lookup_pepper,
-                },
-                headers=headers,
-            )
-        except Exception as e:
-            logger.warning("Error when performing a v2 3pid lookup: %s", e)
-            raise SynapseError(
-                500, "Unknown error occurred during identity server lookup"
-            )
+        return stream_id
 
-        # Check for a mapping from what we looked up to an MXID
-        if "mappings" not in lookup_results or not isinstance(
-            lookup_results["mappings"], dict
-        ):
-            logger.warning("No results from 3pid lookup")
-            return None
-
-        # Return the MXID if it's available, or None otherwise
-        mxid = lookup_results["mappings"].get(lookup_value)
-        return mxid
-
-    @defer.inlineCallbacks
-    def _verify_any_signature(self, data, server_hostname):
-        if server_hostname not in data["signatures"]:
-            raise AuthError(401, "No signature from server %s" % (server_hostname,))
-        for key_name, signature in data["signatures"][server_hostname].items():
-            key_data = yield self.simple_http_client.get_json(
-                "%s%s/_matrix/identity/api/v1/pubkey/%s"
-                % (id_server_scheme, server_hostname, key_name)
-            )
-            if "public_key" not in key_data:
-                raise AuthError(
-                    401, "No public key named %s from %s" % (key_name, server_hostname)
-                )
-            verify_signed_json(
-                data,
-                server_hostname,
-                decode_verify_key_bytes(
-                    key_name, decode_base64(key_data["public_key"])
-                ),
-            )
-            return
-
-    @defer.inlineCallbacks
-    def _make_and_store_3pid_invite(
+    async def _make_and_store_3pid_invite(
         self,
-        requester,
-        id_server,
-        medium,
-        address,
-        room_id,
-        user,
-        txn_id,
-        id_access_token=None,
-    ):
-        room_state = yield self.state_handler.get_current_state(room_id)
+        requester: Requester,
+        id_server: str,
+        medium: str,
+        address: str,
+        room_id: str,
+        user: UserID,
+        txn_id: Optional[str],
+        id_access_token: Optional[str] = None,
+    ) -> int:
+        room_state = await self.state_handler.get_current_state(room_id)
 
         inviter_display_name = ""
         inviter_avatar_url = ""
@@ -935,25 +830,31 @@ class RoomMemberHandler(object):
         if room_avatar_event:
             room_avatar_url = room_avatar_event.content.get("url", "")
 
-        token, public_keys, fallback_public_key, display_name = (
-            yield self._ask_id_server_for_third_party_invite(
-                requester=requester,
-                id_server=id_server,
-                medium=medium,
-                address=address,
-                room_id=room_id,
-                inviter_user_id=user.to_string(),
-                room_alias=canonical_room_alias,
-                room_avatar_url=room_avatar_url,
-                room_join_rules=room_join_rules,
-                room_name=room_name,
-                inviter_display_name=inviter_display_name,
-                inviter_avatar_url=inviter_avatar_url,
-                id_access_token=id_access_token,
-            )
+        (
+            token,
+            public_keys,
+            fallback_public_key,
+            display_name,
+        ) = await self.identity_handler.ask_id_server_for_third_party_invite(
+            requester=requester,
+            id_server=id_server,
+            medium=medium,
+            address=address,
+            room_id=room_id,
+            inviter_user_id=user.to_string(),
+            room_alias=canonical_room_alias,
+            room_avatar_url=room_avatar_url,
+            room_join_rules=room_join_rules,
+            room_name=room_name,
+            inviter_display_name=inviter_display_name,
+            inviter_avatar_url=inviter_avatar_url,
+            id_access_token=id_access_token,
         )
 
-        yield self.event_creation_handler.create_and_send_nonmember_event(
+        (
+            event,
+            stream_id,
+        ) = await self.event_creation_handler.create_and_send_nonmember_event(
             requester,
             {
                 "type": EventTypes.ThirdPartyInvite,
@@ -971,146 +872,11 @@ class RoomMemberHandler(object):
             ratelimit=False,
             txn_id=txn_id,
         )
+        return stream_id
 
-    @defer.inlineCallbacks
-    def _ask_id_server_for_third_party_invite(
-        self,
-        requester,
-        id_server,
-        medium,
-        address,
-        room_id,
-        inviter_user_id,
-        room_alias,
-        room_avatar_url,
-        room_join_rules,
-        room_name,
-        inviter_display_name,
-        inviter_avatar_url,
-        id_access_token=None,
-    ):
-        """
-        Asks an identity server for a third party invite.
-
-        Args:
-            requester (Requester)
-            id_server (str): hostname + optional port for the identity server.
-            medium (str): The literal string "email".
-            address (str): The third party address being invited.
-            room_id (str): The ID of the room to which the user is invited.
-            inviter_user_id (str): The user ID of the inviter.
-            room_alias (str): An alias for the room, for cosmetic notifications.
-            room_avatar_url (str): The URL of the room's avatar, for cosmetic
-                notifications.
-            room_join_rules (str): The join rules of the email (e.g. "public").
-            room_name (str): The m.room.name of the room.
-            inviter_display_name (str): The current display name of the
-                inviter.
-            inviter_avatar_url (str): The URL of the inviter's avatar.
-            id_access_token (str|None): The access token to authenticate to the identity
-                server with
-
-        Returns:
-            A deferred tuple containing:
-                token (str): The token which must be signed to prove authenticity.
-                public_keys ([{"public_key": str, "key_validity_url": str}]):
-                    public_key is a base64-encoded ed25519 public key.
-                fallback_public_key: One element from public_keys.
-                display_name (str): A user-friendly name to represent the invited
-                    user.
-        """
-        invite_config = {
-            "medium": medium,
-            "address": address,
-            "room_id": room_id,
-            "room_alias": room_alias,
-            "room_avatar_url": room_avatar_url,
-            "room_join_rules": room_join_rules,
-            "room_name": room_name,
-            "sender": inviter_user_id,
-            "sender_display_name": inviter_display_name,
-            "sender_avatar_url": inviter_avatar_url,
-        }
-
-        # Add the identity service access token to the JSON body and use the v2
-        # Identity Service endpoints if id_access_token is present
-        data = None
-        base_url = "%s%s/_matrix/identity" % (id_server_scheme, id_server)
-
-        if id_access_token:
-            key_validity_url = "%s%s/_matrix/identity/v2/pubkey/isvalid" % (
-                id_server_scheme,
-                id_server,
-            )
-
-            # Attempt a v2 lookup
-            url = base_url + "/v2/store-invite"
-            try:
-                data = yield self.simple_http_client.post_json_get_json(
-                    url,
-                    invite_config,
-                    {"Authorization": create_id_access_token_header(id_access_token)},
-                )
-            except HttpResponseException as e:
-                if e.code != 404:
-                    logger.info("Failed to POST %s with JSON: %s", url, e)
-                    raise e
-
-        if data is None:
-            key_validity_url = "%s%s/_matrix/identity/api/v1/pubkey/isvalid" % (
-                id_server_scheme,
-                id_server,
-            )
-            url = base_url + "/api/v1/store-invite"
-
-            try:
-                data = yield self.simple_http_client.post_json_get_json(
-                    url, invite_config
-                )
-            except HttpResponseException as e:
-                logger.warning(
-                    "Error trying to call /store-invite on %s%s: %s",
-                    id_server_scheme,
-                    id_server,
-                    e,
-                )
-
-            if data is None:
-                # Some identity servers may only support application/x-www-form-urlencoded
-                # types. This is especially true with old instances of Sydent, see
-                # https://github.com/matrix-org/sydent/pull/170
-                try:
-                    data = yield self.simple_http_client.post_urlencoded_get_json(
-                        url, invite_config
-                    )
-                except HttpResponseException as e:
-                    logger.warning(
-                        "Error calling /store-invite on %s%s with fallback "
-                        "encoding: %s",
-                        id_server_scheme,
-                        id_server,
-                        e,
-                    )
-                    raise e
-
-        # TODO: Check for success
-        token = data["token"]
-        public_keys = data.get("public_keys", [])
-        if "public_key" in data:
-            fallback_public_key = {
-                "public_key": data["public_key"],
-                "key_validity_url": key_validity_url,
-            }
-        else:
-            fallback_public_key = public_keys[0]
-
-        if not public_keys:
-            public_keys.append(fallback_public_key)
-        display_name = data["display_name"]
-        return token, public_keys, fallback_public_key, display_name
-
-    @defer.inlineCallbacks
-    def _is_host_in_room(self, current_state_ids):
+    async def _is_host_in_room(
+        self, current_state_ids: Dict[Tuple[str, str], str]
+    ) -> bool:
         # Have we just created the room, and is this about to be the very
         # first member event?
         create_event_id = current_state_ids.get(("m.room.create", ""))
@@ -1123,7 +889,7 @@ class RoomMemberHandler(object):
                 continue
 
             event_id = current_state_ids[(etype, state_key)]
-            event = yield self.store.get_event(event_id, allow_none=True)
+            event = await self.store.get_event(event_id, allow_none=True)
             if not event:
                 continue
 
@@ -1132,11 +898,10 @@ class RoomMemberHandler(object):
 
         return False
 
-    @defer.inlineCallbacks
-    def _is_server_notice_room(self, room_id):
+    async def _is_server_notice_room(self, room_id: str) -> bool:
         if self._server_notices_mxid is None:
             return False
-        user_ids = yield self.store.get_users_in_room(room_id)
+        user_ids = await self.store.get_users_in_room(room_id)
         return self._server_notices_mxid in user_ids
 
 
@@ -1148,20 +913,21 @@ class RoomMemberMasterHandler(RoomMemberHandler):
         self.distributor.declare("user_joined_room")
         self.distributor.declare("user_left_room")
 
-    @defer.inlineCallbacks
-    def _is_remote_room_too_complex(self, room_id, remote_room_hosts):
+    async def _is_remote_room_too_complex(
+        self, room_id: str, remote_room_hosts: List[str]
+    ) -> Optional[bool]:
         """
         Check if complexity of a remote room is too great.
 
         Args:
-            room_id (str)
-            remote_room_hosts (list[str])
+            room_id
+            remote_room_hosts
 
         Returns: bool of whether the complexity is too great, or None
             if unable to be fetched
         """
         max_complexity = self.hs.config.limit_remote_rooms.complexity
-        complexity = yield self.federation_handler.get_room_complexity(
+        complexity = await self.federation_handler.get_room_complexity(
             remote_room_hosts, room_id
         )
 
@@ -1169,23 +935,26 @@ class RoomMemberMasterHandler(RoomMemberHandler):
             return complexity["v1"] > max_complexity
         return None
 
-    @defer.inlineCallbacks
-    def _is_local_room_too_complex(self, room_id):
+    async def _is_local_room_too_complex(self, room_id: str) -> bool:
         """
         Check if the complexity of a local room is too great.
 
         Args:
-            room_id (str)
-
-        Returns: bool
+            room_id: The room ID to check for complexity.
         """
         max_complexity = self.hs.config.limit_remote_rooms.complexity
-        complexity = yield self.store.get_room_complexity(room_id)
+        complexity = await self.store.get_room_complexity(room_id)
 
         return complexity["v1"] > max_complexity
 
-    @defer.inlineCallbacks
-    def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
+    async def _remote_join(
+        self,
+        requester: Requester,
+        remote_room_hosts: List[str],
+        room_id: str,
+        user: UserID,
+        content: dict,
+    ) -> Tuple[str, int]:
         """Implements RoomMemberHandler._remote_join
         """
         # filter ourselves out of remote_room_hosts: do_invite_join ignores it
@@ -1200,7 +969,7 @@ class RoomMemberMasterHandler(RoomMemberHandler):
 
         if self.hs.config.limit_remote_rooms.enabled:
             # Fetch the room complexity
-            too_complex = yield self._is_remote_room_too_complex(
+            too_complex = await self._is_remote_room_too_complex(
                 room_id, remote_room_hosts
             )
             if too_complex is True:
@@ -1214,28 +983,28 @@ class RoomMemberMasterHandler(RoomMemberHandler):
         # join dance for now, since we're kinda implicitly checking
         # that we are allowed to join when we decide whether or not we
         # need to do the invite/join dance.
-        yield self.federation_handler.do_invite_join(
+        event_id, stream_id = await self.federation_handler.do_invite_join(
             remote_room_hosts, room_id, user.to_string(), content
         )
-        yield self._user_joined_room(user, room_id)
+        await self._user_joined_room(user, room_id)
 
         # Check the room we just joined wasn't too large, if we didn't fetch the
         # complexity of it before.
         if self.hs.config.limit_remote_rooms.enabled:
             if too_complex is False:
                 # We checked, and we're under the limit.
-                return
+                return event_id, stream_id
 
             # Check again, but with the local state events
-            too_complex = yield self._is_local_room_too_complex(room_id)
+            too_complex = await self._is_local_room_too_complex(room_id)
 
             if too_complex is False:
                 # We're under the limit.
-                return
+                return event_id, stream_id
 
             # The room is too large. Leave.
             requester = types.create_requester(user, None, False, None)
-            yield self.update_membership(
+            await self.update_membership(
                 requester=requester, target=user, room_id=room_id, action="leave"
             )
             raise SynapseError(
@@ -1244,16 +1013,24 @@ class RoomMemberMasterHandler(RoomMemberHandler):
                 errcode=Codes.RESOURCE_LIMIT_EXCEEDED,
             )
 
-    @defer.inlineCallbacks
-    def _remote_reject_invite(self, requester, remote_room_hosts, room_id, target):
+        return event_id, stream_id
+
+    async def _remote_reject_invite(
+        self,
+        requester: Requester,
+        remote_room_hosts: List[str],
+        room_id: str,
+        target: UserID,
+        content: dict,
+    ) -> Tuple[Optional[str], int]:
         """Implements RoomMemberHandler._remote_reject_invite
         """
         fed_handler = self.federation_handler
         try:
-            ret = yield fed_handler.do_remotely_reject_invite(
-                remote_room_hosts, room_id, target.to_string()
+            event, stream_id = await fed_handler.do_remotely_reject_invite(
+                remote_room_hosts, room_id, target.to_string(), content=content,
             )
-            return ret
+            return event.event_id, stream_id
         except Exception as e:
             # if we were unable to reject the exception, just mark
             # it as rejected on our end and plough ahead.
@@ -1263,24 +1040,23 @@ class RoomMemberMasterHandler(RoomMemberHandler):
             #
             logger.warning("Failed to reject invite: %s", e)
 
-            yield self.store.locally_reject_invite(target.to_string(), room_id)
-            return {}
+            stream_id = await self.locally_reject_invite(target.to_string(), room_id)
+            return None, stream_id
 
-    def _user_joined_room(self, target, room_id):
+    async def _user_joined_room(self, target: UserID, room_id: str) -> None:
         """Implements RoomMemberHandler._user_joined_room
         """
-        return user_joined_room(self.distributor, target, room_id)
+        user_joined_room(self.distributor, target, room_id)
 
-    def _user_left_room(self, target, room_id):
+    async def _user_left_room(self, target: UserID, room_id: str) -> None:
         """Implements RoomMemberHandler._user_left_room
         """
-        return user_left_room(self.distributor, target, room_id)
+        user_left_room(self.distributor, target, room_id)
 
-    @defer.inlineCallbacks
-    def forget(self, user, room_id):
+    async def forget(self, user: UserID, room_id: str) -> None:
         user_id = user.to_string()
 
-        member = yield self.state_handler.get_current_state(
+        member = await self.state_handler.get_current_state(
             room_id=room_id, event_type=EventTypes.Member, state_key=user_id
         )
         membership = member.membership if member else None
@@ -1292,4 +1068,4 @@ class RoomMemberMasterHandler(RoomMemberHandler):
             raise SynapseError(400, "User %s in room %s" % (user_id, room_id))
 
         if membership:
-            yield self.store.forget(user_id, room_id)
+            await self.store.forget(user_id, room_id)
diff --git a/synapse/handlers/room_member_worker.py b/synapse/handlers/room_member_worker.py
index 75e96ae1a2..02e0c4103d 100644
--- a/synapse/handlers/room_member_worker.py
+++ b/synapse/handlers/room_member_worker.py
@@ -14,8 +14,7 @@
 # limitations under the License.
 
 import logging
-
-from twisted.internet import defer
+from typing import List, Optional, Tuple
 
 from synapse.api.errors import SynapseError
 from synapse.handlers.room_member import RoomMemberHandler
@@ -24,6 +23,7 @@ from synapse.replication.http.membership import (
     ReplicationRemoteRejectInviteRestServlet as ReplRejectInvite,
     ReplicationUserJoinedLeftRoomRestServlet as ReplJoinedLeft,
 )
+from synapse.types import Requester, UserID
 
 logger = logging.getLogger(__name__)
 
@@ -36,14 +36,20 @@ class RoomMemberWorkerHandler(RoomMemberHandler):
         self._remote_reject_client = ReplRejectInvite.make_client(hs)
         self._notify_change_client = ReplJoinedLeft.make_client(hs)
 
-    @defer.inlineCallbacks
-    def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
+    async def _remote_join(
+        self,
+        requester: Requester,
+        remote_room_hosts: List[str],
+        room_id: str,
+        user: UserID,
+        content: dict,
+    ) -> Tuple[str, int]:
         """Implements RoomMemberHandler._remote_join
         """
         if len(remote_room_hosts) == 0:
             raise SynapseError(404, "No known servers")
 
-        ret = yield self._remote_join_client(
+        ret = await self._remote_join_client(
             requester=requester,
             remote_room_hosts=remote_room_hosts,
             room_id=room_id,
@@ -51,30 +57,39 @@ class RoomMemberWorkerHandler(RoomMemberHandler):
             content=content,
         )
 
-        yield self._user_joined_room(user, room_id)
+        await self._user_joined_room(user, room_id)
 
-        return ret
+        return ret["event_id"], ret["stream_id"]
 
-    def _remote_reject_invite(self, requester, remote_room_hosts, room_id, target):
+    async def _remote_reject_invite(
+        self,
+        requester: Requester,
+        remote_room_hosts: List[str],
+        room_id: str,
+        target: UserID,
+        content: dict,
+    ) -> Tuple[Optional[str], int]:
         """Implements RoomMemberHandler._remote_reject_invite
         """
-        return self._remote_reject_client(
+        ret = await self._remote_reject_client(
             requester=requester,
             remote_room_hosts=remote_room_hosts,
             room_id=room_id,
             user_id=target.to_string(),
+            content=content,
         )
+        return ret["event_id"], ret["stream_id"]
 
-    def _user_joined_room(self, target, room_id):
+    async def _user_joined_room(self, target: UserID, room_id: str) -> None:
         """Implements RoomMemberHandler._user_joined_room
         """
-        return self._notify_change_client(
+        await self._notify_change_client(
             user_id=target.to_string(), room_id=room_id, change="joined"
         )
 
-    def _user_left_room(self, target, room_id):
+    async def _user_left_room(self, target: UserID, room_id: str) -> None:
         """Implements RoomMemberHandler._user_left_room
         """
-        return self._notify_change_client(
+        await self._notify_change_client(
             user_id=target.to_string(), room_id=room_id, change="left"
         )
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index a1ce6929cf..abecaa8313 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -13,45 +13,93 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import re
+from typing import Callable, Dict, Optional, Set, Tuple
 
 import attr
 import saml2
+import saml2.response
 from saml2.client import Saml2Client
 
 from synapse.api.errors import SynapseError
+from synapse.config import ConfigError
 from synapse.http.servlet import parse_string
-from synapse.rest.client.v1.login import SSOAuthHandler
+from synapse.http.site import SynapseRequest
+from synapse.module_api import ModuleApi
+from synapse.types import (
+    UserID,
+    map_username_to_mxid_localpart,
+    mxid_localpart_allowed_characters,
+)
+from synapse.util.async_helpers import Linearizer
+from synapse.util.iterutils import chunk_seq
 
 logger = logging.getLogger(__name__)
 
 
+@attr.s
+class Saml2SessionData:
+    """Data we track about SAML2 sessions"""
+
+    # time the session was created, in milliseconds
+    creation_time = attr.ib()
+    # The user interactive authentication session ID associated with this SAML
+    # session (or None if this SAML session is for an initial login).
+    ui_auth_session_id = attr.ib(type=Optional[str], default=None)
+
+
 class SamlHandler:
     def __init__(self, hs):
         self._saml_client = Saml2Client(hs.config.saml2_sp_config)
-        self._sso_auth_handler = SSOAuthHandler(hs)
+        self._auth = hs.get_auth()
+        self._auth_handler = hs.get_auth_handler()
+        self._registration_handler = hs.get_registration_handler()
+
+        self._clock = hs.get_clock()
+        self._datastore = hs.get_datastore()
+        self._hostname = hs.hostname
+        self._saml2_session_lifetime = hs.config.saml2_session_lifetime
+        self._grandfathered_mxid_source_attribute = (
+            hs.config.saml2_grandfathered_mxid_source_attribute
+        )
+
+        # plugin to do custom mapping from saml response to mxid
+        self._user_mapping_provider = hs.config.saml2_user_mapping_provider_class(
+            hs.config.saml2_user_mapping_provider_config,
+            ModuleApi(hs, hs.get_auth_handler()),
+        )
+
+        # identifier for the external_ids table
+        self._auth_provider_id = "saml"
 
         # a map from saml session id to Saml2SessionData object
         self._outstanding_requests_dict = {}
 
-        self._clock = hs.get_clock()
-        self._saml2_session_lifetime = hs.config.saml2_session_lifetime
+        # a lock on the mappings
+        self._mapping_lock = Linearizer(name="saml_mapping", clock=self._clock)
 
-    def handle_redirect_request(self, client_redirect_url):
+    def handle_redirect_request(
+        self, client_redirect_url: bytes, ui_auth_session_id: Optional[str] = None
+    ) -> bytes:
         """Handle an incoming request to /login/sso/redirect
 
         Args:
-            client_redirect_url (bytes): the URL that we should redirect the
+            client_redirect_url: the URL that we should redirect the
                 client to when everything is done
+            ui_auth_session_id: The session ID of the ongoing UI Auth (or
+                None if this is a login).
 
         Returns:
-            bytes: URL to redirect to
+            URL to redirect to
         """
         reqid, info = self._saml_client.prepare_for_authenticate(
             relay_state=client_redirect_url
         )
 
         now = self._clock.time_msec()
-        self._outstanding_requests_dict[reqid] = Saml2SessionData(creation_time=now)
+        self._outstanding_requests_dict[reqid] = Saml2SessionData(
+            creation_time=now, ui_auth_session_id=ui_auth_session_id,
+        )
 
         for key, value in info["headers"]:
             if key == "Location":
@@ -60,15 +108,15 @@ class SamlHandler:
         # this shouldn't happen!
         raise Exception("prepare_for_authenticate didn't return a Location header")
 
-    def handle_saml_response(self, request):
+    async def handle_saml_response(self, request: SynapseRequest) -> None:
         """Handle an incoming request to /_matrix/saml2/authn_response
 
         Args:
-            request (SynapseRequest): the incoming request from the browser. We'll
+            request: the incoming request from the browser. We'll
                 respond to it with a redirect.
 
         Returns:
-            Deferred[none]: Completes once we have handled the request.
+            Completes once we have handled the request.
         """
         resp_bytes = parse_string(request, "SAMLResponse", required=True)
         relay_state = parse_string(request, "RelayState", required=True)
@@ -77,6 +125,37 @@ class SamlHandler:
         # the dict.
         self.expire_sessions()
 
+        user_id, current_session = await self._map_saml_response_to_user(
+            resp_bytes, relay_state
+        )
+
+        # Complete the interactive auth session or the login.
+        if current_session and current_session.ui_auth_session_id:
+            await self._auth_handler.complete_sso_ui_auth(
+                user_id, current_session.ui_auth_session_id, request
+            )
+
+        else:
+            await self._auth_handler.complete_sso_login(user_id, request, relay_state)
+
+    async def _map_saml_response_to_user(
+        self, resp_bytes: str, client_redirect_url: str
+    ) -> Tuple[str, Optional[Saml2SessionData]]:
+        """
+        Given a sample response, retrieve the cached session and user for it.
+
+        Args:
+            resp_bytes: The SAML response.
+            client_redirect_url: The redirect URL passed in by the client.
+
+        Returns:
+             Tuple of the user ID and SAML session associated with this response.
+
+        Raises:
+            SynapseError if there was a problem with the response.
+            RedirectException: some mapping providers may raise this if they need
+                to redirect to an interstitial page.
+        """
         try:
             saml2_auth = self._saml_client.parse_authn_request_response(
                 resp_bytes,
@@ -84,26 +163,123 @@ class SamlHandler:
                 outstanding=self._outstanding_requests_dict,
             )
         except Exception as e:
-            logger.warning("Exception parsing SAML2 response: %s", e)
             raise SynapseError(400, "Unable to parse SAML2 response: %s" % (e,))
 
         if saml2_auth.not_signed:
-            logger.warning("SAML2 response was not signed")
             raise SynapseError(400, "SAML2 response was not signed")
 
-        if "uid" not in saml2_auth.ava:
-            logger.warning("SAML2 response lacks a 'uid' attestation")
-            raise SynapseError(400, "uid not in SAML2 response")
+        logger.debug("SAML2 response: %s", saml2_auth.origxml)
+        for assertion in saml2_auth.assertions:
+            # kibana limits the length of a log field, whereas this is all rather
+            # useful, so split it up.
+            count = 0
+            for part in chunk_seq(str(assertion), 10000):
+                logger.info(
+                    "SAML2 assertion: %s%s", "(%i)..." % (count,) if count else "", part
+                )
+                count += 1
 
-        self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
+        logger.info("SAML2 mapped attributes: %s", saml2_auth.ava)
 
-        username = saml2_auth.ava["uid"][0]
-        displayName = saml2_auth.ava.get("displayName", [None])[0]
+        current_session = self._outstanding_requests_dict.pop(
+            saml2_auth.in_response_to, None
+        )
 
-        return self._sso_auth_handler.on_successful_auth(
-            username, request, relay_state, user_display_name=displayName
+        remote_user_id = self._user_mapping_provider.get_remote_user_id(
+            saml2_auth, client_redirect_url
         )
 
+        if not remote_user_id:
+            raise Exception("Failed to extract remote user id from SAML response")
+
+        with (await self._mapping_lock.queue(self._auth_provider_id)):
+            # first of all, check if we already have a mapping for this user
+            logger.info(
+                "Looking for existing mapping for user %s:%s",
+                self._auth_provider_id,
+                remote_user_id,
+            )
+            registered_user_id = await self._datastore.get_user_by_external_id(
+                self._auth_provider_id, remote_user_id
+            )
+            if registered_user_id is not None:
+                logger.info("Found existing mapping %s", registered_user_id)
+                return registered_user_id, current_session
+
+            # backwards-compatibility hack: see if there is an existing user with a
+            # suitable mapping from the uid
+            if (
+                self._grandfathered_mxid_source_attribute
+                and self._grandfathered_mxid_source_attribute in saml2_auth.ava
+            ):
+                attrval = saml2_auth.ava[self._grandfathered_mxid_source_attribute][0]
+                user_id = UserID(
+                    map_username_to_mxid_localpart(attrval), self._hostname
+                ).to_string()
+                logger.info(
+                    "Looking for existing account based on mapped %s %s",
+                    self._grandfathered_mxid_source_attribute,
+                    user_id,
+                )
+
+                users = await self._datastore.get_users_by_id_case_insensitive(user_id)
+                if users:
+                    registered_user_id = list(users.keys())[0]
+                    logger.info("Grandfathering mapping to %s", registered_user_id)
+                    await self._datastore.record_user_external_id(
+                        self._auth_provider_id, remote_user_id, registered_user_id
+                    )
+                    return registered_user_id, current_session
+
+            # Map saml response to user attributes using the configured mapping provider
+            for i in range(1000):
+                attribute_dict = self._user_mapping_provider.saml_response_to_user_attributes(
+                    saml2_auth, i, client_redirect_url=client_redirect_url,
+                )
+
+                logger.debug(
+                    "Retrieved SAML attributes from user mapping provider: %s "
+                    "(attempt %d)",
+                    attribute_dict,
+                    i,
+                )
+
+                localpart = attribute_dict.get("mxid_localpart")
+                if not localpart:
+                    raise Exception(
+                        "Error parsing SAML2 response: SAML mapping provider plugin "
+                        "did not return a mxid_localpart value"
+                    )
+
+                displayname = attribute_dict.get("displayname")
+                emails = attribute_dict.get("emails", [])
+
+                # Check if this mxid already exists
+                if not await self._datastore.get_users_by_id_case_insensitive(
+                    UserID(localpart, self._hostname).to_string()
+                ):
+                    # This mxid is free
+                    break
+            else:
+                # Unable to generate a username in 1000 iterations
+                # Break and return error to the user
+                raise SynapseError(
+                    500, "Unable to generate a Matrix ID from the SAML response"
+                )
+
+            logger.info("Mapped SAML user to local part %s", localpart)
+
+            registered_user_id = await self._registration_handler.register_user(
+                localpart=localpart,
+                default_display_name=displayname,
+                bind_emails=emails,
+            )
+
+            await self._datastore.record_user_external_id(
+                self._auth_provider_id, remote_user_id, registered_user_id
+            )
+            return registered_user_id, current_session
+
     def expire_sessions(self):
         expire_before = self._clock.time_msec() - self._saml2_session_lifetime
         to_expire = set()
@@ -115,9 +291,146 @@ class SamlHandler:
             del self._outstanding_requests_dict[reqid]
 
 
+DOT_REPLACE_PATTERN = re.compile(
+    ("[^%s]" % (re.escape("".join(mxid_localpart_allowed_characters)),))
+)
+
+
+def dot_replace_for_mxid(username: str) -> str:
+    """Replace any characters which are not allowed in Matrix IDs with a dot."""
+    username = username.lower()
+    username = DOT_REPLACE_PATTERN.sub(".", username)
+
+    # regular mxids aren't allowed to start with an underscore either
+    username = re.sub("^_", "", username)
+    return username
+
+
+MXID_MAPPER_MAP = {
+    "hexencode": map_username_to_mxid_localpart,
+    "dotreplace": dot_replace_for_mxid,
+}  # type: Dict[str, Callable[[str], str]]
+
+
 @attr.s
-class Saml2SessionData:
-    """Data we track about SAML2 sessions"""
+class SamlConfig(object):
+    mxid_source_attribute = attr.ib()
+    mxid_mapper = attr.ib()
 
-    # time the session was created, in milliseconds
-    creation_time = attr.ib()
+
+class DefaultSamlMappingProvider(object):
+    __version__ = "0.0.1"
+
+    def __init__(self, parsed_config: SamlConfig, module_api: ModuleApi):
+        """The default SAML user mapping provider
+
+        Args:
+            parsed_config: Module configuration
+            module_api: module api proxy
+        """
+        self._mxid_source_attribute = parsed_config.mxid_source_attribute
+        self._mxid_mapper = parsed_config.mxid_mapper
+
+        self._grandfathered_mxid_source_attribute = (
+            module_api._hs.config.saml2_grandfathered_mxid_source_attribute
+        )
+
+    def get_remote_user_id(
+        self, saml_response: saml2.response.AuthnResponse, client_redirect_url: str
+    ) -> str:
+        """Extracts the remote user id from the SAML response"""
+        try:
+            return saml_response.ava["uid"][0]
+        except KeyError:
+            logger.warning("SAML2 response lacks a 'uid' attestation")
+            raise SynapseError(400, "'uid' not in SAML2 response")
+
+    def saml_response_to_user_attributes(
+        self,
+        saml_response: saml2.response.AuthnResponse,
+        failures: int,
+        client_redirect_url: str,
+    ) -> dict:
+        """Maps some text from a SAML response to attributes of a new user
+
+        Args:
+            saml_response: A SAML auth response object
+
+            failures: How many times a call to this function with this
+                saml_response has resulted in a failure
+
+            client_redirect_url: where the client wants to redirect to
+
+        Returns:
+            dict: A dict containing new user attributes. Possible keys:
+                * mxid_localpart (str): Required. The localpart of the user's mxid
+                * displayname (str): The displayname of the user
+                * emails (list[str]): Any emails for the user
+        """
+        try:
+            mxid_source = saml_response.ava[self._mxid_source_attribute][0]
+        except KeyError:
+            logger.warning(
+                "SAML2 response lacks a '%s' attestation", self._mxid_source_attribute,
+            )
+            raise SynapseError(
+                400, "%s not in SAML2 response" % (self._mxid_source_attribute,)
+            )
+
+        # Use the configured mapper for this mxid_source
+        base_mxid_localpart = self._mxid_mapper(mxid_source)
+
+        # Append suffix integer if last call to this function failed to produce
+        # a usable mxid
+        localpart = base_mxid_localpart + (str(failures) if failures else "")
+
+        # Retrieve the display name from the saml response
+        # If displayname is None, the mxid_localpart will be used instead
+        displayname = saml_response.ava.get("displayName", [None])[0]
+
+        # Retrieve any emails present in the saml response
+        emails = saml_response.ava.get("email", [])
+
+        return {
+            "mxid_localpart": localpart,
+            "displayname": displayname,
+            "emails": emails,
+        }
+
+    @staticmethod
+    def parse_config(config: dict) -> SamlConfig:
+        """Parse the dict provided by the homeserver's config
+        Args:
+            config: A dictionary containing configuration options for this provider
+        Returns:
+            SamlConfig: A custom config object for this module
+        """
+        # Parse config options and use defaults where necessary
+        mxid_source_attribute = config.get("mxid_source_attribute", "uid")
+        mapping_type = config.get("mxid_mapping", "hexencode")
+
+        # Retrieve the associating mapping function
+        try:
+            mxid_mapper = MXID_MAPPER_MAP[mapping_type]
+        except KeyError:
+            raise ConfigError(
+                "saml2_config.user_mapping_provider.config: '%s' is not a valid "
+                "mxid_mapping value" % (mapping_type,)
+            )
+
+        return SamlConfig(mxid_source_attribute, mxid_mapper)
+
+    @staticmethod
+    def get_saml_attributes(config: SamlConfig) -> Tuple[Set[str], Set[str]]:
+        """Returns the required attributes of a SAML
+
+        Args:
+            config: A SamlConfig object containing configuration params for this provider
+
+        Returns:
+            The first set equates to the saml auth response
+                attributes that are required for the module to function, whereas the
+                second set consists of those attributes which can be used if
+                available, but are not necessary
+        """
+        return {"uid", config.mxid_source_attribute}, {"displayName", "email"}
diff --git a/synapse/handlers/search.py b/synapse/handlers/search.py
index cd5e90bacb..4d40d3ac9c 100644
--- a/synapse/handlers/search.py
+++ b/synapse/handlers/search.py
@@ -18,10 +18,8 @@ import logging
 
 from unpaddedbase64 import decode_base64, encode_base64
 
-from twisted.internet import defer
-
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import SynapseError
+from synapse.api.errors import NotFoundError, SynapseError
 from synapse.api.filtering import Filter
 from synapse.storage.state import StateFilter
 from synapse.visibility import filter_events_for_client
@@ -35,9 +33,11 @@ class SearchHandler(BaseHandler):
     def __init__(self, hs):
         super(SearchHandler, self).__init__(hs)
         self._event_serializer = hs.get_event_client_serializer()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
+        self.auth = hs.get_auth()
 
-    @defer.inlineCallbacks
-    def get_old_rooms_from_upgraded_room(self, room_id):
+    async def get_old_rooms_from_upgraded_room(self, room_id):
         """Retrieves room IDs of old rooms in the history of an upgraded room.
 
         We do so by checking the m.room.create event of the room for a
@@ -51,28 +51,42 @@ class SearchHandler(BaseHandler):
             room_id (str): id of the room to search through.
 
         Returns:
-            Deferred[iterable[unicode]]: predecessor room ids
+            Deferred[iterable[str]]: predecessor room ids
         """
 
         historical_room_ids = []
 
-        while True:
-            predecessor = yield self.store.get_room_predecessor(room_id)
+        # The initial room must have been known for us to get this far
+        predecessor = await self.store.get_room_predecessor(room_id)
 
-            # If no predecessor, assume we've hit a dead end
+        while True:
             if not predecessor:
+                # We have reached the end of the chain of predecessors
+                break
+
+            if not isinstance(predecessor.get("room_id"), str):
+                # This predecessor object is malformed. Exit here
+                break
+
+            predecessor_room_id = predecessor["room_id"]
+
+            # Don't add it to the list until we have checked that we are in the room
+            try:
+                next_predecessor_room = await self.store.get_room_predecessor(
+                    predecessor_room_id
+                )
+            except NotFoundError:
+                # The predecessor is not a known room, so we are done here
                 break
 
-            # Add predecessor's room ID
-            historical_room_ids.append(predecessor["room_id"])
+            historical_room_ids.append(predecessor_room_id)
 
-            # Scan through the old room for further predecessors
-            room_id = predecessor["room_id"]
+            # And repeat
+            predecessor = next_predecessor_room
 
         return historical_room_ids
 
-    @defer.inlineCallbacks
-    def search(self, user, content, batch=None):
+    async def search(self, user, content, batch=None):
         """Performs a full text search for a user.
 
         Args:
@@ -161,12 +175,12 @@ class SearchHandler(BaseHandler):
         search_filter = Filter(filter_dict)
 
         # TODO: Search through left rooms too
-        rooms = yield self.store.get_rooms_for_user_where_membership_is(
+        rooms = await self.store.get_rooms_for_local_user_where_membership_is(
             user.to_string(),
             membership_list=[Membership.JOIN],
             # membership_list=[Membership.JOIN, Membership.LEAVE, Membership.Ban],
         )
-        room_ids = set(r.room_id for r in rooms)
+        room_ids = {r.room_id for r in rooms}
 
         # If doing a subset of all rooms seearch, check if any of the rooms
         # are from an upgraded room, and search their contents as well
@@ -174,7 +188,7 @@ class SearchHandler(BaseHandler):
             historical_room_ids = []
             for room_id in search_filter.rooms:
                 # Add any previous rooms to the search if they exist
-                ids = yield self.get_old_rooms_from_upgraded_room(room_id)
+                ids = await self.get_old_rooms_from_upgraded_room(room_id)
                 historical_room_ids += ids
 
             # Prevent any historical events from being filtered
@@ -205,7 +219,7 @@ class SearchHandler(BaseHandler):
         count = None
 
         if order_by == "rank":
-            search_result = yield self.store.search_msgs(room_ids, search_term, keys)
+            search_result = await self.store.search_msgs(room_ids, search_term, keys)
 
             count = search_result["count"]
 
@@ -220,8 +234,8 @@ class SearchHandler(BaseHandler):
 
             filtered_events = search_filter.filter([r["event"] for r in results])
 
-            events = yield filter_events_for_client(
-                self.store, user.to_string(), filtered_events
+            events = await filter_events_for_client(
+                self.storage, user.to_string(), filtered_events
             )
 
             events.sort(key=lambda e: -rank_map[e.event_id])
@@ -249,7 +263,7 @@ class SearchHandler(BaseHandler):
             # But only go around 5 times since otherwise synapse will be sad.
             while len(room_events) < search_filter.limit() and i < 5:
                 i += 1
-                search_result = yield self.store.search_rooms(
+                search_result = await self.store.search_rooms(
                     room_ids,
                     search_term,
                     keys,
@@ -270,8 +284,8 @@ class SearchHandler(BaseHandler):
 
                 filtered_events = search_filter.filter([r["event"] for r in results])
 
-                events = yield filter_events_for_client(
-                    self.store, user.to_string(), filtered_events
+                events = await filter_events_for_client(
+                    self.storage, user.to_string(), filtered_events
                 )
 
                 room_events.extend(events)
@@ -325,11 +339,11 @@ class SearchHandler(BaseHandler):
         # If client has asked for "context" for each event (i.e. some surrounding
         # events and state), fetch that
         if event_context is not None:
-            now_token = yield self.hs.get_event_sources().get_current_token()
+            now_token = await self.hs.get_event_sources().get_current_token()
 
             contexts = {}
             for event in allowed_events:
-                res = yield self.store.get_events_around(
+                res = await self.store.get_events_around(
                     event.room_id, event.event_id, before_limit, after_limit
                 )
 
@@ -339,12 +353,12 @@ class SearchHandler(BaseHandler):
                     len(res["events_after"]),
                 )
 
-                res["events_before"] = yield filter_events_for_client(
-                    self.store, user.to_string(), res["events_before"]
+                res["events_before"] = await filter_events_for_client(
+                    self.storage, user.to_string(), res["events_before"]
                 )
 
-                res["events_after"] = yield filter_events_for_client(
-                    self.store, user.to_string(), res["events_after"]
+                res["events_after"] = await filter_events_for_client(
+                    self.storage, user.to_string(), res["events_after"]
                 )
 
                 res["start"] = now_token.copy_and_replace(
@@ -356,12 +370,12 @@ class SearchHandler(BaseHandler):
                 ).to_string()
 
                 if include_profile:
-                    senders = set(
+                    senders = {
                         ev.sender
                         for ev in itertools.chain(
                             res["events_before"], [event], res["events_after"]
                         )
-                    )
+                    }
 
                     if res["events_after"]:
                         last_event_id = res["events_after"][-1].event_id
@@ -372,7 +386,7 @@ class SearchHandler(BaseHandler):
                         [(EventTypes.Member, sender) for sender in senders]
                     )
 
-                    state = yield self.store.get_state_for_event(
+                    state = await self.state_store.get_state_for_event(
                         last_event_id, state_filter
                     )
 
@@ -394,22 +408,18 @@ class SearchHandler(BaseHandler):
         time_now = self.clock.time_msec()
 
         for context in contexts.values():
-            context["events_before"] = (
-                yield self._event_serializer.serialize_events(
-                    context["events_before"], time_now
-                )
+            context["events_before"] = await self._event_serializer.serialize_events(
+                context["events_before"], time_now
             )
-            context["events_after"] = (
-                yield self._event_serializer.serialize_events(
-                    context["events_after"], time_now
-                )
+            context["events_after"] = await self._event_serializer.serialize_events(
+                context["events_after"], time_now
             )
 
         state_results = {}
         if include_state:
-            rooms = set(e.room_id for e in allowed_events)
+            rooms = {e.room_id for e in allowed_events}
             for room_id in rooms:
-                state = yield self.state_handler.get_current_state(room_id)
+                state = await self.state_handler.get_current_state(room_id)
                 state_results[room_id] = list(state.values())
 
             state_results.values()
@@ -423,7 +433,7 @@ class SearchHandler(BaseHandler):
                 {
                     "rank": rank_map[e.event_id],
                     "result": (
-                        yield self._event_serializer.serialize_event(e, time_now)
+                        await self._event_serializer.serialize_event(e, time_now)
                     ),
                     "context": contexts.get(e.event_id, {}),
                 }
@@ -438,7 +448,7 @@ class SearchHandler(BaseHandler):
         if state_results:
             s = {}
             for room_id, state in state_results.items():
-                s[room_id] = yield self._event_serializer.serialize_events(
+                s[room_id] = await self._event_serializer.serialize_events(
                     state, time_now
                 )
 
diff --git a/synapse/handlers/set_password.py b/synapse/handlers/set_password.py
index d90c9e0108..4d245b618b 100644
--- a/synapse/handlers/set_password.py
+++ b/synapse/handlers/set_password.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-
-from twisted.internet import defer
+from typing import Optional
 
 from synapse.api.errors import Codes, StoreError, SynapseError
+from synapse.types import Requester
 
 from ._base import BaseHandler
 
@@ -30,32 +30,37 @@ class SetPasswordHandler(BaseHandler):
         super(SetPasswordHandler, self).__init__(hs)
         self._auth_handler = hs.get_auth_handler()
         self._device_handler = hs.get_device_handler()
+        self._password_policy_handler = hs.get_password_policy_handler()
 
-    @defer.inlineCallbacks
-    def set_password(self, user_id, newpassword, requester=None):
+    async def set_password(
+        self,
+        user_id: str,
+        password_hash: str,
+        logout_devices: bool,
+        requester: Optional[Requester] = None,
+    ):
         if not self.hs.config.password_localdb_enabled:
             raise SynapseError(403, "Password change disabled", errcode=Codes.FORBIDDEN)
 
-        password_hash = yield self._auth_handler.hash(newpassword)
-
-        except_device_id = requester.device_id if requester else None
-        except_access_token_id = requester.access_token_id if requester else None
-
         try:
-            yield self.store.user_set_password_hash(user_id, password_hash)
+            await self.store.user_set_password_hash(user_id, password_hash)
         except StoreError as e:
             if e.code == 404:
                 raise SynapseError(404, "Unknown user", Codes.NOT_FOUND)
             raise e
 
-        # we want to log out all of the user's other sessions. First delete
-        # all his other devices.
-        yield self._device_handler.delete_all_devices_for_user(
-            user_id, except_device_id=except_device_id
-        )
-
-        # and now delete any access tokens which weren't associated with
-        # devices (or were associated with this device).
-        yield self._auth_handler.delete_access_tokens_for_user(
-            user_id, except_token_id=except_access_token_id
-        )
+        # Optionally, log out all of the user's other sessions.
+        if logout_devices:
+            except_device_id = requester.device_id if requester else None
+            except_access_token_id = requester.access_token_id if requester else None
+
+            # First delete all of their other devices.
+            await self._device_handler.delete_all_devices_for_user(
+                user_id, except_device_id=except_device_id
+            )
+
+            # and now delete any access tokens which weren't associated with
+            # devices (or were associated with this device).
+            await self._auth_handler.delete_access_tokens_for_user(
+                user_id, except_token_id=except_access_token_id
+            )
diff --git a/synapse/handlers/state_deltas.py b/synapse/handlers/state_deltas.py
index f065970c40..8590c1eff4 100644
--- a/synapse/handlers/state_deltas.py
+++ b/synapse/handlers/state_deltas.py
@@ -15,8 +15,6 @@
 
 import logging
 
-from twisted.internet import defer
-
 logger = logging.getLogger(__name__)
 
 
@@ -24,8 +22,7 @@ class StateDeltasHandler(object):
     def __init__(self, hs):
         self.store = hs.get_datastore()
 
-    @defer.inlineCallbacks
-    def _get_key_change(self, prev_event_id, event_id, key_name, public_value):
+    async def _get_key_change(self, prev_event_id, event_id, key_name, public_value):
         """Given two events check if the `key_name` field in content changed
         from not matching `public_value` to doing so.
 
@@ -41,10 +38,10 @@ class StateDeltasHandler(object):
         prev_event = None
         event = None
         if prev_event_id:
-            prev_event = yield self.store.get_event(prev_event_id, allow_none=True)
+            prev_event = await self.store.get_event(prev_event_id, allow_none=True)
 
         if event_id:
-            event = yield self.store.get_event(event_id, allow_none=True)
+            event = await self.store.get_event(event_id, allow_none=True)
 
         if not event and not prev_event:
             logger.debug("Neither event exists: %r %r", prev_event_id, event_id)
diff --git a/synapse/handlers/stats.py b/synapse/handlers/stats.py
index cbac7c347a..149f861239 100644
--- a/synapse/handlers/stats.py
+++ b/synapse/handlers/stats.py
@@ -16,17 +16,14 @@
 import logging
 from collections import Counter
 
-from twisted.internet import defer
-
 from synapse.api.constants import EventTypes, Membership
-from synapse.handlers.state_deltas import StateDeltasHandler
 from synapse.metrics import event_processing_positions
 from synapse.metrics.background_process_metrics import run_as_background_process
 
 logger = logging.getLogger(__name__)
 
 
-class StatsHandler(StateDeltasHandler):
+class StatsHandler:
     """Handles keeping the *_stats tables updated with a simple time-series of
     information about the users, rooms and media on the server, such that admins
     have some idea of who is consuming their resources.
@@ -35,7 +32,6 @@ class StatsHandler(StateDeltasHandler):
     """
 
     def __init__(self, hs):
-        super(StatsHandler, self).__init__(hs)
         self.hs = hs
         self.store = hs.get_datastore()
         self.state = hs.get_state_handler()
@@ -45,6 +41,8 @@ class StatsHandler(StateDeltasHandler):
         self.is_mine_id = hs.is_mine_id
         self.stats_bucket_size = hs.config.stats_bucket_size
 
+        self.stats_enabled = hs.config.stats_enabled
+
         # The current position in the current_state_delta stream
         self.pos = None
 
@@ -61,25 +59,23 @@ class StatsHandler(StateDeltasHandler):
     def notify_new_event(self):
         """Called when there may be more deltas to process
         """
-        if not self.hs.config.stats_enabled or self._is_processing:
+        if not self.stats_enabled or self._is_processing:
             return
 
         self._is_processing = True
 
-        @defer.inlineCallbacks
-        def process():
+        async def process():
             try:
-                yield self._unsafe_process()
+                await self._unsafe_process()
             finally:
                 self._is_processing = False
 
         run_as_background_process("stats.notify_new_event", process)
 
-    @defer.inlineCallbacks
-    def _unsafe_process(self):
+    async def _unsafe_process(self):
         # If self.pos is None then means we haven't fetched it from DB
         if self.pos is None:
-            self.pos = yield self.store.get_stats_positions()
+            self.pos = await self.store.get_stats_positions()
 
         # Loop round handling deltas until we're up to date
 
@@ -87,24 +83,29 @@ class StatsHandler(StateDeltasHandler):
             # Be sure to read the max stream_ordering *before* checking if there are any outstanding
             # deltas, since there is otherwise a chance that we could miss updates which arrive
             # after we check the deltas.
-            room_max_stream_ordering = yield self.store.get_room_max_stream_ordering()
+            room_max_stream_ordering = self.store.get_room_max_stream_ordering()
             if self.pos == room_max_stream_ordering:
                 break
 
-            deltas = yield self.store.get_current_state_deltas(self.pos)
+            logger.debug(
+                "Processing room stats %s->%s", self.pos, room_max_stream_ordering
+            )
+            max_pos, deltas = await self.store.get_current_state_deltas(
+                self.pos, room_max_stream_ordering
+            )
 
             if deltas:
                 logger.debug("Handling %d state deltas", len(deltas))
-                room_deltas, user_deltas = yield self._handle_deltas(deltas)
-
-                max_pos = deltas[-1]["stream_id"]
+                room_deltas, user_deltas = await self._handle_deltas(deltas)
             else:
                 room_deltas = {}
                 user_deltas = {}
-                max_pos = room_max_stream_ordering
 
             # Then count deltas for total_events and total_event_bytes.
-            room_count, user_count = yield self.store.get_changes_room_total_events_and_bytes(
+            (
+                room_count,
+                user_count,
+            ) = await self.store.get_changes_room_total_events_and_bytes(
                 self.pos, max_pos
             )
 
@@ -118,7 +119,7 @@ class StatsHandler(StateDeltasHandler):
             logger.debug("user_deltas: %s", user_deltas)
 
             # Always call this so that we update the stats position.
-            yield self.store.bulk_update_stats_delta(
+            await self.store.bulk_update_stats_delta(
                 self.clock.time_msec(),
                 updates={"room": room_deltas, "user": user_deltas},
                 stream_id=max_pos,
@@ -130,13 +131,12 @@ class StatsHandler(StateDeltasHandler):
 
             self.pos = max_pos
 
-    @defer.inlineCallbacks
-    def _handle_deltas(self, deltas):
+    async def _handle_deltas(self, deltas):
         """Called with the state deltas to process
 
         Returns:
-            Deferred[tuple[dict[str, Counter], dict[str, counter]]]
-            Resovles to two dicts, the room deltas and the user deltas,
+            tuple[dict[str, Counter], dict[str, counter]]
+            Two dicts: the room deltas and the user deltas,
             mapping from room/user ID to changes in the various fields.
         """
 
@@ -155,7 +155,7 @@ class StatsHandler(StateDeltasHandler):
 
             logger.debug("Handling: %r, %r %r, %s", room_id, typ, state_key, event_id)
 
-            token = yield self.store.get_earliest_token_for_stats("room", room_id)
+            token = await self.store.get_earliest_token_for_stats("room", room_id)
 
             # If the earliest token to begin from is larger than our current
             # stream ID, skip processing this delta.
@@ -177,7 +177,7 @@ class StatsHandler(StateDeltasHandler):
 
             sender = None
             if event_id is not None:
-                event = yield self.store.get_event(event_id, allow_none=True)
+                event = await self.store.get_event(event_id, allow_none=True)
                 if event:
                     event_content = event.content or {}
                     sender = event.sender
@@ -193,16 +193,16 @@ class StatsHandler(StateDeltasHandler):
                 room_stats_delta["current_state_events"] += 1
 
             if typ == EventTypes.Member:
-                # we could use _get_key_change here but it's a bit inefficient
-                # given we're not testing for a specific result; might as well
-                # just grab the prev_membership and membership strings and
-                # compare them.
+                # we could use StateDeltasHandler._get_key_change here but it's
+                # a bit inefficient given we're not testing for a specific
+                # result; might as well just grab the prev_membership and
+                # membership strings and compare them.
                 # We take None rather than leave as a previous membership
                 # in the absence of a previous event because we do not want to
                 # reduce the leave count when a new-to-the-room user joins.
                 prev_membership = None
                 if prev_event_id is not None:
-                    prev_event = yield self.store.get_event(
+                    prev_event = await self.store.get_event(
                         prev_event_id, allow_none=True
                     )
                     if prev_event:
@@ -279,7 +279,7 @@ class StatsHandler(StateDeltasHandler):
                 room_state["history_visibility"] = event_content.get(
                     "history_visibility"
                 )
-            elif typ == EventTypes.Encryption:
+            elif typ == EventTypes.RoomEncryption:
                 room_state["encryption"] = event_content.get("algorithm")
             elif typ == EventTypes.Name:
                 room_state["name"] = event_content.get("name")
@@ -293,6 +293,7 @@ class StatsHandler(StateDeltasHandler):
                 room_state["guest_access"] = event_content.get("guest_access")
 
         for room_id, state in room_to_state_updates.items():
-            yield self.store.update_room_state(room_id, state)
+            logger.debug("Updating room_stats_state for %s: %s", room_id, state)
+            await self.store.update_room_state(room_id, state)
 
         return room_to_stats_deltas, user_to_stats_deltas
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 19bca6717f..6bdb24baff 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2015, 2016 OpenMarket Ltd
-# Copyright 2018 New Vector Ltd
+# Copyright 2018, 2019 New Vector Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -14,22 +14,30 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import collections
 import itertools
 import logging
+from typing import Any, Dict, FrozenSet, List, Optional, Set, Tuple
 
 from six import iteritems, itervalues
 
+import attr
 from prometheus_client import Counter
 
-from twisted.internet import defer
-
 from synapse.api.constants import EventTypes, Membership
-from synapse.logging.context import LoggingContext
+from synapse.api.filtering import FilterCollection
+from synapse.events import EventBase
+from synapse.logging.context import current_context
 from synapse.push.clientformat import format_push_rules_for_user
 from synapse.storage.roommember import MemberSummary
 from synapse.storage.state import StateFilter
-from synapse.types import RoomStreamToken
+from synapse.types import (
+    Collection,
+    JsonDict,
+    RoomStreamToken,
+    StateMap,
+    StreamToken,
+    UserID,
+)
 from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.caches.lrucache import LruCache
@@ -64,17 +72,22 @@ LAZY_LOADED_MEMBERS_CACHE_MAX_AGE = 30 * 60 * 1000
 LAZY_LOADED_MEMBERS_CACHE_MAX_SIZE = 100
 
 
-SyncConfig = collections.namedtuple(
-    "SyncConfig", ["user", "filter_collection", "is_guest", "request_key", "device_id"]
-)
+@attr.s(slots=True, frozen=True)
+class SyncConfig:
+    user = attr.ib(type=UserID)
+    filter_collection = attr.ib(type=FilterCollection)
+    is_guest = attr.ib(type=bool)
+    request_key = attr.ib(type=Tuple[Any, ...])
+    device_id = attr.ib(type=str)
 
 
-class TimelineBatch(
-    collections.namedtuple("TimelineBatch", ["prev_batch", "events", "limited"])
-):
-    __slots__ = []
+@attr.s(slots=True, frozen=True)
+class TimelineBatch:
+    prev_batch = attr.ib(type=StreamToken)
+    events = attr.ib(type=List[EventBase])
+    limited = attr.ib(bool)
 
-    def __nonzero__(self):
+    def __nonzero__(self) -> bool:
         """Make the result appear empty if there are no updates. This is used
         to tell if room needs to be part of the sync result.
         """
@@ -83,23 +96,17 @@ class TimelineBatch(
     __bool__ = __nonzero__  # python3
 
 
-class JoinedSyncResult(
-    collections.namedtuple(
-        "JoinedSyncResult",
-        [
-            "room_id",  # str
-            "timeline",  # TimelineBatch
-            "state",  # dict[(str, str), FrozenEvent]
-            "ephemeral",
-            "account_data",
-            "unread_notifications",
-            "summary",
-        ],
-    )
-):
-    __slots__ = []
-
-    def __nonzero__(self):
+@attr.s(slots=True, frozen=True)
+class JoinedSyncResult:
+    room_id = attr.ib(type=str)
+    timeline = attr.ib(type=TimelineBatch)
+    state = attr.ib(type=StateMap[EventBase])
+    ephemeral = attr.ib(type=List[JsonDict])
+    account_data = attr.ib(type=List[JsonDict])
+    unread_notifications = attr.ib(type=JsonDict)
+    summary = attr.ib(type=Optional[JsonDict])
+
+    def __nonzero__(self) -> bool:
         """Make the result appear empty if there are no updates. This is used
         to tell if room needs to be part of the sync result.
         """
@@ -115,20 +122,14 @@ class JoinedSyncResult(
     __bool__ = __nonzero__  # python3
 
 
-class ArchivedSyncResult(
-    collections.namedtuple(
-        "ArchivedSyncResult",
-        [
-            "room_id",  # str
-            "timeline",  # TimelineBatch
-            "state",  # dict[(str, str), FrozenEvent]
-            "account_data",
-        ],
-    )
-):
-    __slots__ = []
-
-    def __nonzero__(self):
+@attr.s(slots=True, frozen=True)
+class ArchivedSyncResult:
+    room_id = attr.ib(type=str)
+    timeline = attr.ib(type=TimelineBatch)
+    state = attr.ib(type=StateMap[EventBase])
+    account_data = attr.ib(type=List[JsonDict])
+
+    def __nonzero__(self) -> bool:
         """Make the result appear empty if there are no updates. This is used
         to tell if room needs to be part of the sync result.
         """
@@ -137,70 +138,88 @@ class ArchivedSyncResult(
     __bool__ = __nonzero__  # python3
 
 
-class InvitedSyncResult(
-    collections.namedtuple(
-        "InvitedSyncResult",
-        ["room_id", "invite"],  # str  # FrozenEvent: the invite event
-    )
-):
-    __slots__ = []
+@attr.s(slots=True, frozen=True)
+class InvitedSyncResult:
+    room_id = attr.ib(type=str)
+    invite = attr.ib(type=EventBase)
 
-    def __nonzero__(self):
+    def __nonzero__(self) -> bool:
         """Invited rooms should always be reported to the client"""
         return True
 
     __bool__ = __nonzero__  # python3
 
 
-class GroupsSyncResult(
-    collections.namedtuple("GroupsSyncResult", ["join", "invite", "leave"])
-):
-    __slots__ = []
+@attr.s(slots=True, frozen=True)
+class GroupsSyncResult:
+    join = attr.ib(type=JsonDict)
+    invite = attr.ib(type=JsonDict)
+    leave = attr.ib(type=JsonDict)
 
-    def __nonzero__(self):
+    def __nonzero__(self) -> bool:
         return bool(self.join or self.invite or self.leave)
 
     __bool__ = __nonzero__  # python3
 
 
-class DeviceLists(
-    collections.namedtuple(
-        "DeviceLists",
-        [
-            "changed",  # list of user_ids whose devices may have changed
-            "left",  # list of user_ids whose devices we no longer track
-        ],
-    )
-):
-    __slots__ = []
+@attr.s(slots=True, frozen=True)
+class DeviceLists:
+    """
+    Attributes:
+        changed: List of user_ids whose devices may have changed
+        left: List of user_ids whose devices we no longer track
+    """
+
+    changed = attr.ib(type=Collection[str])
+    left = attr.ib(type=Collection[str])
 
-    def __nonzero__(self):
+    def __nonzero__(self) -> bool:
         return bool(self.changed or self.left)
 
     __bool__ = __nonzero__  # python3
 
 
-class SyncResult(
-    collections.namedtuple(
-        "SyncResult",
-        [
-            "next_batch",  # Token for the next sync
-            "presence",  # List of presence events for the user.
-            "account_data",  # List of account_data events for the user.
-            "joined",  # JoinedSyncResult for each joined room.
-            "invited",  # InvitedSyncResult for each invited room.
-            "archived",  # ArchivedSyncResult for each archived room.
-            "to_device",  # List of direct messages for the device.
-            "device_lists",  # List of user_ids whose devices have changed
-            "device_one_time_keys_count",  # Dict of algorithm to count for one time keys
-            # for this device
-            "groups",
-        ],
-    )
-):
-    __slots__ = []
-
-    def __nonzero__(self):
+@attr.s
+class _RoomChanges:
+    """The set of room entries to include in the sync, plus the set of joined
+    and left room IDs since last sync.
+    """
+
+    room_entries = attr.ib(type=List["RoomSyncResultBuilder"])
+    invited = attr.ib(type=List[InvitedSyncResult])
+    newly_joined_rooms = attr.ib(type=List[str])
+    newly_left_rooms = attr.ib(type=List[str])
+
+
+@attr.s(slots=True, frozen=True)
+class SyncResult:
+    """
+    Attributes:
+        next_batch: Token for the next sync
+        presence: List of presence events for the user.
+        account_data: List of account_data events for the user.
+        joined: JoinedSyncResult for each joined room.
+        invited: InvitedSyncResult for each invited room.
+        archived: ArchivedSyncResult for each archived room.
+        to_device: List of direct messages for the device.
+        device_lists: List of user_ids whose devices have changed
+        device_one_time_keys_count: Dict of algorithm to count for one time keys
+            for this device
+        groups: Group updates, if any
+    """
+
+    next_batch = attr.ib(type=StreamToken)
+    presence = attr.ib(type=List[JsonDict])
+    account_data = attr.ib(type=List[JsonDict])
+    joined = attr.ib(type=List[JoinedSyncResult])
+    invited = attr.ib(type=List[InvitedSyncResult])
+    archived = attr.ib(type=List[ArchivedSyncResult])
+    to_device = attr.ib(type=List[JsonDict])
+    device_lists = attr.ib(type=DeviceLists)
+    device_one_time_keys_count = attr.ib(type=JsonDict)
+    groups = attr.ib(type=Optional[GroupsSyncResult])
+
+    def __nonzero__(self) -> bool:
         """Make the result appear empty if there are no updates. This is used
         to tell if the notifier needs to wait for more events when polling for
         events.
@@ -230,6 +249,8 @@ class SyncHandler(object):
         self.response_cache = ResponseCache(hs, "sync")
         self.state = hs.get_state_handler()
         self.auth = hs.get_auth()
+        self.storage = hs.get_storage()
+        self.state_store = self.storage.state
 
         # ExpiringCache((User, Device)) -> LruCache(state_key => event_id)
         self.lazy_loaded_members_cache = ExpiringCache(
@@ -239,23 +260,24 @@ class SyncHandler(object):
             expiry_ms=LAZY_LOADED_MEMBERS_CACHE_MAX_AGE,
         )
 
-    @defer.inlineCallbacks
-    def wait_for_sync_for_user(
-        self, sync_config, since_token=None, timeout=0, full_state=False
-    ):
+    async def wait_for_sync_for_user(
+        self,
+        sync_config: SyncConfig,
+        since_token: Optional[StreamToken] = None,
+        timeout: int = 0,
+        full_state: bool = False,
+    ) -> SyncResult:
         """Get the sync for a client if we have new data for it now. Otherwise
         wait for new data to arrive on the server. If the timeout expires, then
         return an empty sync result.
-        Returns:
-            Deferred[SyncResult]
         """
         # If the user is not part of the mau group, then check that limits have
         # not been exceeded (if not part of the group by this point, almost certain
         # auth_blocking will occur)
         user_id = sync_config.user.to_string()
-        yield self.auth.check_auth_blocking(user_id)
+        await self.auth.check_auth_blocking(user_id)
 
-        res = yield self.response_cache.wrap(
+        res = await self.response_cache.wrap(
             sync_config.request_key,
             self._wait_for_sync_for_user,
             sync_config,
@@ -265,8 +287,13 @@ class SyncHandler(object):
         )
         return res
 
-    @defer.inlineCallbacks
-    def _wait_for_sync_for_user(self, sync_config, since_token, timeout, full_state):
+    async def _wait_for_sync_for_user(
+        self,
+        sync_config: SyncConfig,
+        since_token: Optional[StreamToken] = None,
+        timeout: int = 0,
+        full_state: bool = False,
+    ) -> SyncResult:
         if since_token is None:
             sync_type = "initial_sync"
         elif full_state:
@@ -274,14 +301,14 @@ class SyncHandler(object):
         else:
             sync_type = "incremental_sync"
 
-        context = LoggingContext.current_context()
+        context = current_context()
         if context:
             context.tag = sync_type
 
         if timeout == 0 or since_token is None or full_state:
             # we are going to return immediately, so don't bother calling
             # notifier.wait_for_events.
-            result = yield self.current_sync_for_user(
+            result = await self.current_sync_for_user(
                 sync_config, since_token, full_state=full_state
             )
         else:
@@ -289,7 +316,7 @@ class SyncHandler(object):
             def current_sync_callback(before_token, after_token):
                 return self.current_sync_for_user(sync_config, since_token)
 
-            result = yield self.notifier.wait_for_events(
+            result = await self.notifier.wait_for_events(
                 sync_config.user.to_string(),
                 timeout,
                 current_sync_callback,
@@ -305,27 +332,33 @@ class SyncHandler(object):
 
         return result
 
-    def current_sync_for_user(self, sync_config, since_token=None, full_state=False):
+    async def current_sync_for_user(
+        self,
+        sync_config: SyncConfig,
+        since_token: Optional[StreamToken] = None,
+        full_state: bool = False,
+    ) -> SyncResult:
         """Get the sync for client needed to match what the server has now.
-        Returns:
-            A Deferred SyncResult.
         """
-        return self.generate_sync_result(sync_config, since_token, full_state)
+        return await self.generate_sync_result(sync_config, since_token, full_state)
 
-    @defer.inlineCallbacks
-    def push_rules_for_user(self, user):
+    async def push_rules_for_user(self, user: UserID) -> JsonDict:
         user_id = user.to_string()
-        rules = yield self.store.get_push_rules_for_user(user_id)
+        rules = await self.store.get_push_rules_for_user(user_id)
         rules = format_push_rules_for_user(user, rules)
         return rules
 
-    @defer.inlineCallbacks
-    def ephemeral_by_room(self, sync_result_builder, now_token, since_token=None):
+    async def ephemeral_by_room(
+        self,
+        sync_result_builder: "SyncResultBuilder",
+        now_token: StreamToken,
+        since_token: Optional[StreamToken] = None,
+    ) -> Tuple[StreamToken, Dict[str, List[JsonDict]]]:
         """Get the ephemeral events for each room the user is in
         Args:
-            sync_result_builder(SyncResultBuilder)
-            now_token (StreamToken): Where the server is currently up to.
-            since_token (StreamToken): Where the server was when the client
+            sync_result_builder
+            now_token: Where the server is currently up to.
+            since_token: Where the server was when the client
                 last synced.
         Returns:
             A tuple of the now StreamToken, updated to reflect the which typing
@@ -341,7 +374,7 @@ class SyncHandler(object):
             room_ids = sync_result_builder.joined_room_ids
 
             typing_source = self.event_sources.sources["typing"]
-            typing, typing_key = yield typing_source.get_new_events(
+            typing, typing_key = await typing_source.get_new_events(
                 user=sync_config.user,
                 from_key=typing_key,
                 limit=sync_config.filter_collection.ephemeral_limit(),
@@ -350,7 +383,7 @@ class SyncHandler(object):
             )
             now_token = now_token.copy_and_replace("typing_key", typing_key)
 
-            ephemeral_by_room = {}
+            ephemeral_by_room = {}  # type: JsonDict
 
             for event in typing:
                 # we want to exclude the room_id from the event, but modifying the
@@ -363,7 +396,7 @@ class SyncHandler(object):
             receipt_key = since_token.receipt_key if since_token else "0"
 
             receipt_source = self.event_sources.sources["receipt"]
-            receipts, receipt_key = yield receipt_source.get_new_events(
+            receipts, receipt_key = await receipt_source.get_new_events(
                 user=sync_config.user,
                 from_key=receipt_key,
                 limit=sync_config.filter_collection.ephemeral_limit(),
@@ -380,16 +413,15 @@ class SyncHandler(object):
 
         return now_token, ephemeral_by_room
 
-    @defer.inlineCallbacks
-    def _load_filtered_recents(
+    async def _load_filtered_recents(
         self,
-        room_id,
-        sync_config,
-        now_token,
-        since_token=None,
-        recents=None,
-        newly_joined_room=False,
-    ):
+        room_id: str,
+        sync_config: SyncConfig,
+        now_token: StreamToken,
+        since_token: Optional[StreamToken] = None,
+        potential_recents: Optional[List[EventBase]] = None,
+        newly_joined_room: bool = False,
+    ) -> TimelineBatch:
         """
         Returns:
             a Deferred TimelineBatch
@@ -400,24 +432,32 @@ class SyncHandler(object):
                 sync_config.filter_collection.blocks_all_room_timeline()
             )
 
-            if recents is None or newly_joined_room or timeline_limit < len(recents):
+            if (
+                potential_recents is None
+                or newly_joined_room
+                or timeline_limit < len(potential_recents)
+            ):
                 limited = True
             else:
                 limited = False
 
-            if recents:
-                recents = sync_config.filter_collection.filter_room_timeline(recents)
+            if potential_recents:
+                recents = sync_config.filter_collection.filter_room_timeline(
+                    potential_recents
+                )
 
                 # We check if there are any state events, if there are then we pass
                 # all current state events to the filter_events function. This is to
                 # ensure that we always include current state in the timeline
-                current_state_ids = frozenset()
+                current_state_ids = frozenset()  # type: FrozenSet[str]
                 if any(e.is_state() for e in recents):
-                    current_state_ids = yield self.state.get_current_state_ids(room_id)
-                    current_state_ids = frozenset(itervalues(current_state_ids))
+                    current_state_ids_map = await self.state.get_current_state_ids(
+                        room_id
+                    )
+                    current_state_ids = frozenset(itervalues(current_state_ids_map))
 
-                recents = yield filter_events_for_client(
-                    self.store,
+                recents = await filter_events_for_client(
+                    self.storage,
                     sync_config.user.to_string(),
                     recents,
                     always_include_ids=current_state_ids,
@@ -447,14 +487,14 @@ class SyncHandler(object):
                 # Otherwise, we want to return the last N events in the room
                 # in toplogical ordering.
                 if since_key:
-                    events, end_key = yield self.store.get_room_events_stream_for_room(
+                    events, end_key = await self.store.get_room_events_stream_for_room(
                         room_id,
                         limit=load_limit + 1,
                         from_key=since_key,
                         to_key=end_key,
                     )
                 else:
-                    events, end_key = yield self.store.get_recent_events_for_room(
+                    events, end_key = await self.store.get_recent_events_for_room(
                         room_id, limit=load_limit + 1, end_token=end_key
                     )
                 loaded_recents = sync_config.filter_collection.filter_room_timeline(
@@ -466,11 +506,13 @@ class SyncHandler(object):
                 # ensure that we always include current state in the timeline
                 current_state_ids = frozenset()
                 if any(e.is_state() for e in loaded_recents):
-                    current_state_ids = yield self.state.get_current_state_ids(room_id)
-                    current_state_ids = frozenset(itervalues(current_state_ids))
+                    current_state_ids_map = await self.state.get_current_state_ids(
+                        room_id
+                    )
+                    current_state_ids = frozenset(itervalues(current_state_ids_map))
 
-                loaded_recents = yield filter_events_for_client(
-                    self.store,
+                loaded_recents = await filter_events_for_client(
+                    self.storage,
                     sync_config.user.to_string(),
                     loaded_recents,
                     always_include_ids=current_state_ids,
@@ -496,20 +538,17 @@ class SyncHandler(object):
             limited=limited or newly_joined_room,
         )
 
-    @defer.inlineCallbacks
-    def get_state_after_event(self, event, state_filter=StateFilter.all()):
+    async def get_state_after_event(
+        self, event: EventBase, state_filter: StateFilter = StateFilter.all()
+    ) -> StateMap[str]:
         """
         Get the room state after the given event
 
         Args:
-            event(synapse.events.EventBase): event of interest
-            state_filter (StateFilter): The state filter used to fetch state
-                from the database.
-
-        Returns:
-            A Deferred map from ((type, state_key)->Event)
+            event: event of interest
+            state_filter: The state filter used to fetch state from the database.
         """
-        state_ids = yield self.store.get_state_ids_for_event(
+        state_ids = await self.state_store.get_state_ids_for_event(
             event.event_id, state_filter=state_filter
         )
         if event.is_state():
@@ -517,30 +556,30 @@ class SyncHandler(object):
             state_ids[(event.type, event.state_key)] = event.event_id
         return state_ids
 
-    @defer.inlineCallbacks
-    def get_state_at(self, room_id, stream_position, state_filter=StateFilter.all()):
+    async def get_state_at(
+        self,
+        room_id: str,
+        stream_position: StreamToken,
+        state_filter: StateFilter = StateFilter.all(),
+    ) -> StateMap[str]:
         """ Get the room state at a particular stream position
 
         Args:
-            room_id(str): room for which to get state
-            stream_position(StreamToken): point at which to get state
-            state_filter (StateFilter): The state filter used to fetch state
-                from the database.
-
-        Returns:
-            A Deferred map from ((type, state_key)->Event)
+            room_id: room for which to get state
+            stream_position: point at which to get state
+            state_filter: The state filter used to fetch state from the database.
         """
         # FIXME this claims to get the state at a stream position, but
         # get_recent_events_for_room operates by topo ordering. This therefore
         # does not reliably give you the state at the given stream position.
         # (https://github.com/matrix-org/synapse/issues/3305)
-        last_events, _ = yield self.store.get_recent_events_for_room(
+        last_events, _ = await self.store.get_recent_events_for_room(
             room_id, end_token=stream_position.room_key, limit=1
         )
 
         if last_events:
             last_event = last_events[-1]
-            state = yield self.get_state_after_event(
+            state = await self.get_state_after_event(
                 last_event, state_filter=state_filter
             )
 
@@ -549,30 +588,31 @@ class SyncHandler(object):
             state = {}
         return state
 
-    @defer.inlineCallbacks
-    def compute_summary(self, room_id, sync_config, batch, state, now_token):
+    async def compute_summary(
+        self,
+        room_id: str,
+        sync_config: SyncConfig,
+        batch: TimelineBatch,
+        state: StateMap[EventBase],
+        now_token: StreamToken,
+    ) -> Optional[JsonDict]:
         """ Works out a room summary block for this room, summarising the number
         of joined members in the room, and providing the 'hero' members if the
         room has no name so clients can consistently name rooms.  Also adds
         state events to 'state' if needed to describe the heroes.
 
-        Args:
-            room_id(str):
-            sync_config(synapse.handlers.sync.SyncConfig):
-            batch(synapse.handlers.sync.TimelineBatch): The timeline batch for
-                the room that will be sent to the user.
-            state(dict): dict of (type, state_key) -> Event as returned by
-                compute_state_delta
-            now_token(str): Token of the end of the current batch.
-
-        Returns:
-             A deferred dict describing the room summary
+        Args
+            room_id
+            sync_config
+            batch: The timeline batch for the room that will be sent to the user.
+            state: State as returned by compute_state_delta
+            now_token: Token of the end of the current batch.
         """
 
         # FIXME: we could/should get this from room_stats when matthew/stats lands
 
         # FIXME: this promulgates https://github.com/matrix-org/synapse/issues/3305
-        last_events, _ = yield self.store.get_recent_event_ids_for_room(
+        last_events, _ = await self.store.get_recent_event_ids_for_room(
             room_id, end_token=now_token.room_key, limit=1
         )
 
@@ -580,7 +620,7 @@ class SyncHandler(object):
             return None
 
         last_event = last_events[-1]
-        state_ids = yield self.store.get_state_ids_for_event(
+        state_ids = await self.state_store.get_state_ids_for_event(
             last_event.event_id,
             state_filter=StateFilter.from_types(
                 [(EventTypes.Name, ""), (EventTypes.CanonicalAlias, "")]
@@ -588,7 +628,7 @@ class SyncHandler(object):
         )
 
         # this is heavily cached, thus: fast.
-        details = yield self.store.get_room_summary(room_id)
+        details = await self.store.get_room_summary(room_id)
 
         name_id = state_ids.get((EventTypes.Name, ""))
         canonical_alias_id = state_ids.get((EventTypes.CanonicalAlias, ""))
@@ -606,12 +646,12 @@ class SyncHandler(object):
         # calculating heroes. Empty strings are falsey, so we check
         # for the "name" value and default to an empty string.
         if name_id:
-            name = yield self.store.get_event(name_id, allow_none=True)
+            name = await self.store.get_event(name_id, allow_none=True)
             if name and name.content.get("name"):
                 return summary
 
         if canonical_alias_id:
-            canonical_alias = yield self.store.get_event(
+            canonical_alias = await self.store.get_event(
                 canonical_alias_id, allow_none=True
             )
             if canonical_alias and canonical_alias.content.get("alias"):
@@ -642,11 +682,9 @@ class SyncHandler(object):
 
         # FIXME: order by stream ordering rather than as returned by SQL
         if joined_user_ids or invited_user_ids:
-            summary["m.heroes"] = sorted(
-                [user_id for user_id in (joined_user_ids + invited_user_ids)]
-            )[0:5]
+            summary["m.heroes"] = sorted(joined_user_ids + invited_user_ids)[0:5]
         else:
-            summary["m.heroes"] = sorted([user_id for user_id in gone_user_ids])[0:5]
+            summary["m.heroes"] = sorted(gone_user_ids)[0:5]
 
         if not sync_config.filter_collection.lazy_load_members():
             return summary
@@ -657,9 +695,9 @@ class SyncHandler(object):
 
         # track which members the client should already know about via LL:
         # Ones which are already in state...
-        existing_members = set(
+        existing_members = {
             user_id for (typ, user_id) in state.keys() if typ == EventTypes.Member
-        )
+        }
 
         # ...or ones which are in the timeline...
         for ev in batch.events:
@@ -676,7 +714,7 @@ class SyncHandler(object):
             )
         ]
 
-        missing_hero_state = yield self.store.get_events(missing_hero_event_ids)
+        missing_hero_state = await self.store.get_events(missing_hero_event_ids)
         missing_hero_state = missing_hero_state.values()
 
         for s in missing_hero_state:
@@ -685,7 +723,7 @@ class SyncHandler(object):
 
         return summary
 
-    def get_lazy_loaded_members_cache(self, cache_key):
+    def get_lazy_loaded_members_cache(self, cache_key: Tuple[str, str]) -> LruCache:
         cache = self.lazy_loaded_members_cache.get(cache_key)
         if cache is None:
             logger.debug("creating LruCache for %r", cache_key)
@@ -695,25 +733,25 @@ class SyncHandler(object):
             logger.debug("found LruCache for %r", cache_key)
         return cache
 
-    @defer.inlineCallbacks
-    def compute_state_delta(
-        self, room_id, batch, sync_config, since_token, now_token, full_state
-    ):
+    async def compute_state_delta(
+        self,
+        room_id: str,
+        batch: TimelineBatch,
+        sync_config: SyncConfig,
+        since_token: Optional[StreamToken],
+        now_token: StreamToken,
+        full_state: bool,
+    ) -> StateMap[EventBase]:
         """ Works out the difference in state between the start of the timeline
         and the previous sync.
 
         Args:
-            room_id(str):
-            batch(synapse.handlers.sync.TimelineBatch): The timeline batch for
-                the room that will be sent to the user.
-            sync_config(synapse.handlers.sync.SyncConfig):
-            since_token(str|None): Token of the end of the previous batch. May
-                be None.
-            now_token(str): Token of the end of the current batch.
-            full_state(bool): Whether to force returning the full state.
-
-        Returns:
-             A deferred dict of (type, state_key) -> Event
+            room_id:
+            batch: The timeline batch for the room that will be sent to the user.
+            sync_config:
+            since_token: Token of the end of the previous batch. May be None.
+            now_token: Token of the end of the current batch.
+            full_state: Whether to force returning the full state.
         """
         # TODO(mjark) Check if the state events were received by the server
         # after the previous sync, since we need to include those state
@@ -733,10 +771,10 @@ class SyncHandler(object):
                 # We only request state for the members needed to display the
                 # timeline:
 
-                members_to_fetch = set(
+                members_to_fetch = {
                     event.sender  # FIXME: we also care about invite targets etc.
                     for event in batch.events
-                )
+                }
 
                 if full_state:
                     # always make sure we LL ourselves so we know we're in the room
@@ -757,16 +795,16 @@ class SyncHandler(object):
 
             if full_state:
                 if batch:
-                    current_state_ids = yield self.store.get_state_ids_for_event(
+                    current_state_ids = await self.state_store.get_state_ids_for_event(
                         batch.events[-1].event_id, state_filter=state_filter
                     )
 
-                    state_ids = yield self.store.get_state_ids_for_event(
+                    state_ids = await self.state_store.get_state_ids_for_event(
                         batch.events[0].event_id, state_filter=state_filter
                     )
 
                 else:
-                    current_state_ids = yield self.get_state_at(
+                    current_state_ids = await self.get_state_at(
                         room_id, stream_position=now_token, state_filter=state_filter
                     )
 
@@ -781,13 +819,13 @@ class SyncHandler(object):
                 )
             elif batch.limited:
                 if batch:
-                    state_at_timeline_start = yield self.store.get_state_ids_for_event(
+                    state_at_timeline_start = await self.state_store.get_state_ids_for_event(
                         batch.events[0].event_id, state_filter=state_filter
                     )
                 else:
                     # We can get here if the user has ignored the senders of all
                     # the recent events.
-                    state_at_timeline_start = yield self.get_state_at(
+                    state_at_timeline_start = await self.get_state_at(
                         room_id, stream_position=now_token, state_filter=state_filter
                     )
 
@@ -805,19 +843,23 @@ class SyncHandler(object):
                 # about them).
                 state_filter = StateFilter.all()
 
-                state_at_previous_sync = yield self.get_state_at(
+                # If this is an initial sync then full_state should be set, and
+                # that case is handled above. We assert here to ensure that this
+                # is indeed the case.
+                assert since_token is not None
+                state_at_previous_sync = await self.get_state_at(
                     room_id, stream_position=since_token, state_filter=state_filter
                 )
 
                 if batch:
-                    current_state_ids = yield self.store.get_state_ids_for_event(
+                    current_state_ids = await self.state_store.get_state_ids_for_event(
                         batch.events[-1].event_id, state_filter=state_filter
                     )
                 else:
                     # Its not clear how we get here, but empirically we do
                     # (#5407). Logging has been added elsewhere to try and
                     # figure out where this state comes from.
-                    current_state_ids = yield self.get_state_at(
+                    current_state_ids = await self.get_state_at(
                         room_id, stream_position=now_token, state_filter=state_filter
                     )
 
@@ -841,7 +883,7 @@ class SyncHandler(object):
                         # So we fish out all the member events corresponding to the
                         # timeline here, and then dedupe any redundant ones below.
 
-                        state_ids = yield self.store.get_state_ids_for_event(
+                        state_ids = await self.state_store.get_state_ids_for_event(
                             batch.events[0].event_id,
                             # we only want members!
                             state_filter=StateFilter.from_types(
@@ -879,29 +921,30 @@ class SyncHandler(object):
                     if t[0] == EventTypes.Member:
                         cache.set(t[1], event_id)
 
-        state = {}
+        state = {}  # type: Dict[str, EventBase]
         if state_ids:
-            state = yield self.store.get_events(list(state_ids.values()))
+            state = await self.store.get_events(list(state_ids.values()))
 
         return {
             (e.type, e.state_key): e
             for e in sync_config.filter_collection.filter_room_state(
                 list(state.values())
             )
+            if e.type != EventTypes.Aliases  # until MSC2261 or alternative solution
         }
 
-    @defer.inlineCallbacks
-    def unread_notifs_for_room_id(self, room_id, sync_config):
+    async def unread_notifs_for_room_id(
+        self, room_id: str, sync_config: SyncConfig
+    ) -> Optional[Dict[str, str]]:
         with Measure(self.clock, "unread_notifs_for_room_id"):
-            last_unread_event_id = yield self.store.get_last_receipt_event_id_for_user(
+            last_unread_event_id = await self.store.get_last_receipt_event_id_for_user(
                 user_id=sync_config.user.to_string(),
                 room_id=room_id,
                 receipt_type="m.read",
             )
 
-            notifs = []
             if last_unread_event_id:
-                notifs = yield self.store.get_unread_event_push_actions_by_room_for_user(
+                notifs = await self.store.get_unread_event_push_actions_by_room_for_user(
                     room_id, sync_config.user.to_string(), last_unread_event_id
                 )
                 return notifs
@@ -910,25 +953,21 @@ class SyncHandler(object):
         # count is whatever it was last time.
         return None
 
-    @defer.inlineCallbacks
-    def generate_sync_result(self, sync_config, since_token=None, full_state=False):
+    async def generate_sync_result(
+        self,
+        sync_config: SyncConfig,
+        since_token: Optional[StreamToken] = None,
+        full_state: bool = False,
+    ) -> SyncResult:
         """Generates a sync result.
-
-        Args:
-            sync_config (SyncConfig)
-            since_token (StreamToken)
-            full_state (bool)
-
-        Returns:
-            Deferred(SyncResult)
         """
         # NB: The now_token gets changed by some of the generate_sync_* methods,
         # this is due to some of the underlying streams not supporting the ability
         # to query up to a given point.
         # Always use the `now_token` in `SyncResultBuilder`
-        now_token = yield self.event_sources.get_current_token()
+        now_token = await self.event_sources.get_current_token()
 
-        logger.info(
+        logger.debug(
             "Calculating sync response for %r between %s and %s",
             sync_config.user,
             since_token,
@@ -942,10 +981,9 @@ class SyncHandler(object):
             # See https://github.com/matrix-org/matrix-doc/issues/1144
             raise NotImplementedError()
         else:
-            joined_room_ids = yield self.get_rooms_for_user_at(
+            joined_room_ids = await self.get_rooms_for_user_at(
                 user_id, now_token.room_stream_id
             )
-
         sync_result_builder = SyncResultBuilder(
             sync_config,
             full_state,
@@ -954,11 +992,11 @@ class SyncHandler(object):
             joined_room_ids=joined_room_ids,
         )
 
-        account_data_by_room = yield self._generate_sync_entry_for_account_data(
+        account_data_by_room = await self._generate_sync_entry_for_account_data(
             sync_result_builder
         )
 
-        res = yield self._generate_sync_entry_for_rooms(
+        res = await self._generate_sync_entry_for_rooms(
             sync_result_builder, account_data_by_room
         )
         newly_joined_rooms, newly_joined_or_invited_users, _, _ = res
@@ -968,13 +1006,13 @@ class SyncHandler(object):
             since_token is None and sync_config.filter_collection.blocks_all_presence()
         )
         if self.hs_config.use_presence and not block_all_presence_data:
-            yield self._generate_sync_entry_for_presence(
+            await self._generate_sync_entry_for_presence(
                 sync_result_builder, newly_joined_rooms, newly_joined_or_invited_users
             )
 
-        yield self._generate_sync_entry_for_to_device(sync_result_builder)
+        await self._generate_sync_entry_for_to_device(sync_result_builder)
 
-        device_lists = yield self._generate_sync_entry_for_device_list(
+        device_lists = await self._generate_sync_entry_for_device_list(
             sync_result_builder,
             newly_joined_rooms=newly_joined_rooms,
             newly_joined_or_invited_users=newly_joined_or_invited_users,
@@ -983,13 +1021,13 @@ class SyncHandler(object):
         )
 
         device_id = sync_config.device_id
-        one_time_key_counts = {}
+        one_time_key_counts = {}  # type: JsonDict
         if device_id:
-            one_time_key_counts = yield self.store.count_e2e_one_time_keys(
+            one_time_key_counts = await self.store.count_e2e_one_time_keys(
                 user_id, device_id
             )
 
-        yield self._generate_sync_entry_for_groups(sync_result_builder)
+        await self._generate_sync_entry_for_groups(sync_result_builder)
 
         # debug for https://github.com/matrix-org/synapse/issues/4422
         for joined_room in sync_result_builder.joined:
@@ -1013,18 +1051,19 @@ class SyncHandler(object):
         )
 
     @measure_func("_generate_sync_entry_for_groups")
-    @defer.inlineCallbacks
-    def _generate_sync_entry_for_groups(self, sync_result_builder):
+    async def _generate_sync_entry_for_groups(
+        self, sync_result_builder: "SyncResultBuilder"
+    ) -> None:
         user_id = sync_result_builder.sync_config.user.to_string()
         since_token = sync_result_builder.since_token
         now_token = sync_result_builder.now_token
 
         if since_token and since_token.groups_key:
-            results = yield self.store.get_groups_changes_for_user(
+            results = await self.store.get_groups_changes_for_user(
                 user_id, since_token.groups_key, now_token.groups_key
             )
         else:
-            results = yield self.store.get_all_groups_for_user(
+            results = await self.store.get_all_groups_for_user(
                 user_id, now_token.groups_key
             )
 
@@ -1057,30 +1096,24 @@ class SyncHandler(object):
         )
 
     @measure_func("_generate_sync_entry_for_device_list")
-    @defer.inlineCallbacks
-    def _generate_sync_entry_for_device_list(
+    async def _generate_sync_entry_for_device_list(
         self,
-        sync_result_builder,
-        newly_joined_rooms,
-        newly_joined_or_invited_users,
-        newly_left_rooms,
-        newly_left_users,
-    ):
+        sync_result_builder: "SyncResultBuilder",
+        newly_joined_rooms: Set[str],
+        newly_joined_or_invited_users: Set[str],
+        newly_left_rooms: Set[str],
+        newly_left_users: Set[str],
+    ) -> DeviceLists:
         """Generate the DeviceLists section of sync
 
         Args:
-            sync_result_builder (SyncResultBuilder)
-            newly_joined_rooms (set[str]): Set of rooms user has joined since
-                previous sync
-            newly_joined_or_invited_users (set[str]): Set of users that have
-                joined or been invited to a room since previous sync.
-            newly_left_rooms (set[str]): Set of rooms user has left since
+            sync_result_builder
+            newly_joined_rooms: Set of rooms user has joined since previous sync
+            newly_joined_or_invited_users: Set of users that have joined or
+                been invited to a room since previous sync.
+            newly_left_rooms: Set of rooms user has left since previous sync
+            newly_left_users: Set of users that have left a room we're in since
                 previous sync
-            newly_left_users (set[str]): Set of users that have left a room
-                we're in since previous sync
-
-        Returns:
-            Deferred[DeviceLists]
         """
 
         user_id = sync_result_builder.sync_config.user.to_string()
@@ -1106,27 +1139,41 @@ class SyncHandler(object):
             # room with by looking at all users that have left a room plus users
             # that were in a room we've left.
 
-            users_who_share_room = yield self.store.get_users_who_share_room_with_user(
+            users_who_share_room = await self.store.get_users_who_share_room_with_user(
                 user_id
             )
 
+            # Always tell the user about their own devices. We check as the user
+            # ID is almost certainly already included (unless they're not in any
+            # rooms) and taking a copy of the set is relatively expensive.
+            if user_id not in users_who_share_room:
+                users_who_share_room = set(users_who_share_room)
+                users_who_share_room.add(user_id)
+
+            tracked_users = users_who_share_room
+
             # Step 1a, check for changes in devices of users we share a room with
-            users_that_have_changed = yield self.store.get_users_whose_devices_changed(
-                since_token.device_list_key, users_who_share_room
+            users_that_have_changed = await self.store.get_users_whose_devices_changed(
+                since_token.device_list_key, tracked_users
             )
 
             # Step 1b, check for newly joined rooms
             for room_id in newly_joined_rooms:
-                joined_users = yield self.state.get_current_users_in_room(room_id)
+                joined_users = await self.state.get_current_users_in_room(room_id)
                 newly_joined_or_invited_users.update(joined_users)
 
             # TODO: Check that these users are actually new, i.e. either they
             # weren't in the previous sync *or* they left and rejoined.
             users_that_have_changed.update(newly_joined_or_invited_users)
 
+            user_signatures_changed = await self.store.get_users_whose_signatures_changed(
+                user_id, since_token.device_list_key
+            )
+            users_that_have_changed.update(user_signatures_changed)
+
             # Now find users that we no longer track
             for room_id in newly_left_rooms:
-                left_users = yield self.state.get_current_users_in_room(room_id)
+                left_users = await self.state.get_current_users_in_room(room_id)
                 newly_left_users.update(left_users)
 
             # Remove any users that we still share a room with.
@@ -1136,16 +1183,11 @@ class SyncHandler(object):
         else:
             return DeviceLists(changed=[], left=[])
 
-    @defer.inlineCallbacks
-    def _generate_sync_entry_for_to_device(self, sync_result_builder):
+    async def _generate_sync_entry_for_to_device(
+        self, sync_result_builder: "SyncResultBuilder"
+    ) -> None:
         """Generates the portion of the sync response. Populates
         `sync_result_builder` with the result.
-
-        Args:
-            sync_result_builder(SyncResultBuilder)
-
-        Returns:
-            Deferred(dict): A dictionary containing the per room account data.
         """
         user_id = sync_result_builder.sync_config.user.to_string()
         device_id = sync_result_builder.sync_config.device_id
@@ -1158,14 +1200,14 @@ class SyncHandler(object):
             # We only delete messages when a new message comes in, but that's
             # fine so long as we delete them at some point.
 
-            deleted = yield self.store.delete_messages_for_device(
+            deleted = await self.store.delete_messages_for_device(
                 user_id, device_id, since_stream_id
             )
             logger.debug(
                 "Deleted %d to-device messages up to %d", deleted, since_stream_id
             )
 
-            messages, stream_id = yield self.store.get_new_messages_for_device(
+            messages, stream_id = await self.store.get_new_messages_for_device(
                 user_id, device_id, since_stream_id, now_token.to_device_key
             )
 
@@ -1183,42 +1225,45 @@ class SyncHandler(object):
         else:
             sync_result_builder.to_device = []
 
-    @defer.inlineCallbacks
-    def _generate_sync_entry_for_account_data(self, sync_result_builder):
+    async def _generate_sync_entry_for_account_data(
+        self, sync_result_builder: "SyncResultBuilder"
+    ) -> Dict[str, Dict[str, JsonDict]]:
         """Generates the account data portion of the sync response. Populates
         `sync_result_builder` with the result.
 
         Args:
-            sync_result_builder(SyncResultBuilder)
+            sync_result_builder
 
         Returns:
-            Deferred(dict): A dictionary containing the per room account data.
+            A dictionary containing the per room account data.
         """
         sync_config = sync_result_builder.sync_config
         user_id = sync_result_builder.sync_config.user.to_string()
         since_token = sync_result_builder.since_token
 
         if since_token and not sync_result_builder.full_state:
-            account_data, account_data_by_room = (
-                yield self.store.get_updated_account_data_for_user(
-                    user_id, since_token.account_data_key
-                )
+            (
+                account_data,
+                account_data_by_room,
+            ) = await self.store.get_updated_account_data_for_user(
+                user_id, since_token.account_data_key
             )
 
-            push_rules_changed = yield self.store.have_push_rules_changed_for_user(
+            push_rules_changed = await self.store.have_push_rules_changed_for_user(
                 user_id, int(since_token.push_rules_key)
             )
 
             if push_rules_changed:
-                account_data["m.push_rules"] = yield self.push_rules_for_user(
+                account_data["m.push_rules"] = await self.push_rules_for_user(
                     sync_config.user
                 )
         else:
-            account_data, account_data_by_room = (
-                yield self.store.get_account_data_for_user(sync_config.user.to_string())
-            )
+            (
+                account_data,
+                account_data_by_room,
+            ) = await self.store.get_account_data_for_user(sync_config.user.to_string())
 
-            account_data["m.push_rules"] = yield self.push_rules_for_user(
+            account_data["m.push_rules"] = await self.push_rules_for_user(
                 sync_config.user
             )
 
@@ -1233,20 +1278,22 @@ class SyncHandler(object):
 
         return account_data_by_room
 
-    @defer.inlineCallbacks
-    def _generate_sync_entry_for_presence(
-        self, sync_result_builder, newly_joined_rooms, newly_joined_or_invited_users
-    ):
+    async def _generate_sync_entry_for_presence(
+        self,
+        sync_result_builder: "SyncResultBuilder",
+        newly_joined_rooms: Set[str],
+        newly_joined_or_invited_users: Set[str],
+    ) -> None:
         """Generates the presence portion of the sync response. Populates the
         `sync_result_builder` with the result.
 
         Args:
-            sync_result_builder(SyncResultBuilder)
-            newly_joined_rooms(list): List of rooms that the user has joined
-                since the last sync (or empty if an initial sync)
-            newly_joined_or_invited_users(list): List of users that have joined
-                or been invited to rooms since the last sync (or empty if an initial
-                sync)
+            sync_result_builder
+            newly_joined_rooms: Set of rooms that the user has joined since
+                the last sync (or empty if an initial sync)
+            newly_joined_or_invited_users: Set of users that have joined or
+                been invited to rooms since the last sync (or empty if an
+                initial sync)
         """
         now_token = sync_result_builder.now_token
         sync_config = sync_result_builder.sync_config
@@ -1262,7 +1309,7 @@ class SyncHandler(object):
             presence_key = None
             include_offline = False
 
-        presence, presence_key = yield presence_source.get_new_events(
+        presence, presence_key = await presence_source.get_new_events(
             user=user,
             from_key=presence_key,
             is_guest=sync_config.is_guest,
@@ -1274,12 +1321,12 @@ class SyncHandler(object):
 
         extra_users_ids = set(newly_joined_or_invited_users)
         for room_id in newly_joined_rooms:
-            users = yield self.state.get_current_users_in_room(room_id)
+            users = await self.state.get_current_users_in_room(room_id)
             extra_users_ids.update(users)
         extra_users_ids.discard(user.to_string())
 
         if extra_users_ids:
-            states = yield self.presence_handler.get_states(extra_users_ids)
+            states = await self.presence_handler.get_states(extra_users_ids)
             presence.extend(states)
 
             # Deduplicate the presence entries so that there's at most one per user
@@ -1289,17 +1336,20 @@ class SyncHandler(object):
 
         sync_result_builder.presence = presence
 
-    @defer.inlineCallbacks
-    def _generate_sync_entry_for_rooms(self, sync_result_builder, account_data_by_room):
+    async def _generate_sync_entry_for_rooms(
+        self,
+        sync_result_builder: "SyncResultBuilder",
+        account_data_by_room: Dict[str, Dict[str, JsonDict]],
+    ) -> Tuple[Set[str], Set[str], Set[str], Set[str]]:
         """Generates the rooms portion of the sync response. Populates the
         `sync_result_builder` with the result.
 
         Args:
-            sync_result_builder(SyncResultBuilder)
-            account_data_by_room(dict): Dictionary of per room account data
+            sync_result_builder
+            account_data_by_room: Dictionary of per room account data
 
         Returns:
-            Deferred(tuple): Returns a 4-tuple of
+            Returns a 4-tuple of
             `(newly_joined_rooms, newly_joined_or_invited_users,
             newly_left_rooms, newly_left_users)`
         """
@@ -1310,9 +1360,9 @@ class SyncHandler(object):
         )
 
         if block_all_room_ephemeral:
-            ephemeral_by_room = {}
+            ephemeral_by_room = {}  # type: Dict[str, List[JsonDict]]
         else:
-            now_token, ephemeral_by_room = yield self.ephemeral_by_room(
+            now_token, ephemeral_by_room = await self.ephemeral_by_room(
                 sync_result_builder,
                 now_token=sync_result_builder.now_token,
                 since_token=sync_result_builder.since_token,
@@ -1320,20 +1370,20 @@ class SyncHandler(object):
             sync_result_builder.now_token = now_token
 
         # We check up front if anything has changed, if it hasn't then there is
-        # no point in going futher.
+        # no point in going further.
         since_token = sync_result_builder.since_token
         if not sync_result_builder.full_state:
             if since_token and not ephemeral_by_room and not account_data_by_room:
-                have_changed = yield self._have_rooms_changed(sync_result_builder)
+                have_changed = await self._have_rooms_changed(sync_result_builder)
                 if not have_changed:
-                    tags_by_room = yield self.store.get_updated_tags(
+                    tags_by_room = await self.store.get_updated_tags(
                         user_id, since_token.account_data_key
                     )
                     if not tags_by_room:
                         logger.debug("no-oping sync")
-                        return [], [], [], []
+                        return set(), set(), set(), set()
 
-        ignored_account_data = yield self.store.get_global_account_data_by_type_for_user(
+        ignored_account_data = await self.store.get_global_account_data_by_type_for_user(
             "m.ignored_user_list", user_id=user_id
         )
 
@@ -1343,18 +1393,21 @@ class SyncHandler(object):
             ignored_users = frozenset()
 
         if since_token:
-            res = yield self._get_rooms_changed(sync_result_builder, ignored_users)
-            room_entries, invited, newly_joined_rooms, newly_left_rooms = res
-
-            tags_by_room = yield self.store.get_updated_tags(
+            room_changes = await self._get_rooms_changed(
+                sync_result_builder, ignored_users
+            )
+            tags_by_room = await self.store.get_updated_tags(
                 user_id, since_token.account_data_key
             )
         else:
-            res = yield self._get_all_rooms(sync_result_builder, ignored_users)
-            room_entries, invited, newly_joined_rooms = res
-            newly_left_rooms = []
+            room_changes = await self._get_all_rooms(sync_result_builder, ignored_users)
 
-            tags_by_room = yield self.store.get_tags_for_user(user_id)
+            tags_by_room = await self.store.get_tags_for_user(user_id)
+
+        room_entries = room_changes.room_entries
+        invited = room_changes.invited
+        newly_joined_rooms = room_changes.newly_joined_rooms
+        newly_left_rooms = room_changes.newly_left_rooms
 
         def handle_room_entries(room_entry):
             return self._generate_room_entry(
@@ -1367,7 +1420,7 @@ class SyncHandler(object):
                 always_include=sync_result_builder.full_state,
             )
 
-        yield concurrently_execute(handle_room_entries, room_entries, 10)
+        await concurrently_execute(handle_room_entries, room_entries, 10)
 
         sync_result_builder.invited.extend(invited)
 
@@ -1395,14 +1448,15 @@ class SyncHandler(object):
         newly_left_users -= newly_joined_or_invited_users
 
         return (
-            newly_joined_rooms,
+            set(newly_joined_rooms),
             newly_joined_or_invited_users,
-            newly_left_rooms,
+            set(newly_left_rooms),
             newly_left_users,
         )
 
-    @defer.inlineCallbacks
-    def _have_rooms_changed(self, sync_result_builder):
+    async def _have_rooms_changed(
+        self, sync_result_builder: "SyncResultBuilder"
+    ) -> bool:
         """Returns whether there may be any new events that should be sent down
         the sync. Returns True if there are.
         """
@@ -1413,7 +1467,7 @@ class SyncHandler(object):
         assert since_token
 
         # Get a list of membership change events that have happened.
-        rooms_changed = yield self.store.get_membership_changes_for_user(
+        rooms_changed = await self.store.get_membership_changes_for_user(
             user_id, since_token.room_key, now_token.room_key
         )
 
@@ -1426,23 +1480,10 @@ class SyncHandler(object):
                 return True
         return False
 
-    @defer.inlineCallbacks
-    def _get_rooms_changed(self, sync_result_builder, ignored_users):
+    async def _get_rooms_changed(
+        self, sync_result_builder: "SyncResultBuilder", ignored_users: Set[str]
+    ) -> _RoomChanges:
         """Gets the the changes that have happened since the last sync.
-
-        Args:
-            sync_result_builder(SyncResultBuilder)
-            ignored_users(set(str)): Set of users ignored by user.
-
-        Returns:
-            Deferred(tuple): Returns a tuple of the form:
-            `(room_entries, invited_rooms, newly_joined_rooms, newly_left_rooms)`
-
-            where:
-                room_entries is a list [RoomSyncResultBuilder]
-                invited_rooms is a list [InvitedSyncResult]
-                newly_joined_rooms is a list[str] of room ids
-                newly_left_rooms is a list[str] of room ids
         """
         user_id = sync_result_builder.sync_config.user.to_string()
         since_token = sync_result_builder.since_token
@@ -1452,11 +1493,11 @@ class SyncHandler(object):
         assert since_token
 
         # Get a list of membership change events that have happened.
-        rooms_changed = yield self.store.get_membership_changes_for_user(
+        rooms_changed = await self.store.get_membership_changes_for_user(
             user_id, since_token.room_key, now_token.room_key
         )
 
-        mem_change_events_by_room_id = {}
+        mem_change_events_by_room_id = {}  # type: Dict[str, List[EventBase]]
         for event in rooms_changed:
             mem_change_events_by_room_id.setdefault(event.room_id, []).append(event)
 
@@ -1465,7 +1506,7 @@ class SyncHandler(object):
         room_entries = []
         invited = []
         for room_id, events in iteritems(mem_change_events_by_room_id):
-            logger.info(
+            logger.debug(
                 "Membership changes in %s: [%s]",
                 room_id,
                 ", ".join(("%s (%s)" % (e.event_id, e.membership) for e in events)),
@@ -1490,11 +1531,11 @@ class SyncHandler(object):
                 continue
 
             if room_id in sync_result_builder.joined_room_ids or has_join:
-                old_state_ids = yield self.get_state_at(room_id, since_token)
+                old_state_ids = await self.get_state_at(room_id, since_token)
                 old_mem_ev_id = old_state_ids.get((EventTypes.Member, user_id), None)
                 old_mem_ev = None
                 if old_mem_ev_id:
-                    old_mem_ev = yield self.store.get_event(
+                    old_mem_ev = await self.store.get_event(
                         old_mem_ev_id, allow_none=True
                     )
 
@@ -1527,13 +1568,13 @@ class SyncHandler(object):
                     newly_left_rooms.append(room_id)
                 else:
                     if not old_state_ids:
-                        old_state_ids = yield self.get_state_at(room_id, since_token)
+                        old_state_ids = await self.get_state_at(room_id, since_token)
                         old_mem_ev_id = old_state_ids.get(
                             (EventTypes.Member, user_id), None
                         )
                         old_mem_ev = None
                         if old_mem_ev_id:
-                            old_mem_ev = yield self.store.get_event(
+                            old_mem_ev = await self.store.get_event(
                                 old_mem_ev_id, allow_none=True
                             )
                     if old_mem_ev and old_mem_ev.membership == Membership.JOIN:
@@ -1557,7 +1598,7 @@ class SyncHandler(object):
 
             if leave_events:
                 leave_event = leave_events[-1]
-                leave_stream_token = yield self.store.get_stream_token_for_event(
+                leave_stream_token = await self.store.get_stream_token_for_event(
                     leave_event.event_id
                 )
                 leave_token = since_token.copy_and_replace(
@@ -1575,7 +1616,7 @@ class SyncHandler(object):
                 # This is all screaming out for a refactor, as the logic here is
                 # subtle and the moving parts numerous.
                 if leave_event.internal_metadata.is_out_of_band_membership():
-                    batch_events = [leave_event]
+                    batch_events = [leave_event]  # type: Optional[List[EventBase]]
                 else:
                     batch_events = None
 
@@ -1594,7 +1635,7 @@ class SyncHandler(object):
         timeline_limit = sync_config.filter_collection.timeline_limit()
 
         # Get all events for rooms we're currently joined to.
-        room_to_events = yield self.store.get_room_events_stream_for_rooms(
+        room_to_events = await self.store.get_room_events_stream_for_rooms(
             room_ids=sync_result_builder.joined_room_ids,
             from_key=since_token.room_key,
             to_key=now_token.room_key,
@@ -1602,7 +1643,7 @@ class SyncHandler(object):
         )
 
         # We loop through all room ids, even if there are no new events, in case
-        # there are non room events taht we need to notify about.
+        # there are non room events that we need to notify about.
         for room_id in sync_result_builder.joined_room_ids:
             room_entry = room_to_events.get(room_id, None)
 
@@ -1641,19 +1682,17 @@ class SyncHandler(object):
                 )
             room_entries.append(entry)
 
-        return room_entries, invited, newly_joined_rooms, newly_left_rooms
+        return _RoomChanges(room_entries, invited, newly_joined_rooms, newly_left_rooms)
 
-    @defer.inlineCallbacks
-    def _get_all_rooms(self, sync_result_builder, ignored_users):
+    async def _get_all_rooms(
+        self, sync_result_builder: "SyncResultBuilder", ignored_users: Set[str]
+    ) -> _RoomChanges:
         """Returns entries for all rooms for the user.
 
         Args:
-            sync_result_builder(SyncResultBuilder)
-            ignored_users(set(str)): Set of users ignored by user.
+            sync_result_builder
+            ignored_users: Set of users ignored by user.
 
-        Returns:
-            Deferred(tuple): Returns a tuple of the form:
-            `([RoomSyncResultBuilder], [InvitedSyncResult], [])`
         """
 
         user_id = sync_result_builder.sync_config.user.to_string()
@@ -1668,7 +1707,7 @@ class SyncHandler(object):
             Membership.BAN,
         )
 
-        room_list = yield self.store.get_rooms_for_user_where_membership_is(
+        room_list = await self.store.get_rooms_for_local_user_where_membership_is(
             user_id=user_id, membership_list=membership_list
         )
 
@@ -1691,7 +1730,7 @@ class SyncHandler(object):
             elif event.membership == Membership.INVITE:
                 if event.sender in ignored_users:
                     continue
-                invite = yield self.store.get_event(event.event_id)
+                invite = await self.store.get_event(event.event_id)
                 invited.append(InvitedSyncResult(room_id=event.room_id, invite=invite))
             elif event.membership in (Membership.LEAVE, Membership.BAN):
                 # Always send down rooms we were banned or kicked from.
@@ -1715,31 +1754,30 @@ class SyncHandler(object):
                     )
                 )
 
-        return room_entries, invited, []
+        return _RoomChanges(room_entries, invited, [], [])
 
-    @defer.inlineCallbacks
-    def _generate_room_entry(
+    async def _generate_room_entry(
         self,
-        sync_result_builder,
-        ignored_users,
-        room_builder,
-        ephemeral,
-        tags,
-        account_data,
-        always_include=False,
+        sync_result_builder: "SyncResultBuilder",
+        ignored_users: Set[str],
+        room_builder: "RoomSyncResultBuilder",
+        ephemeral: List[JsonDict],
+        tags: Optional[List[JsonDict]],
+        account_data: Dict[str, JsonDict],
+        always_include: bool = False,
     ):
         """Populates the `joined` and `archived` section of `sync_result_builder`
         based on the `room_builder`.
 
         Args:
-            sync_result_builder(SyncResultBuilder)
-            ignored_users(set(str)): Set of users ignored by user.
-            room_builder(RoomSyncResultBuilder)
-            ephemeral(list): List of new ephemeral events for room
-            tags(list): List of *all* tags for room, or None if there has been
+            sync_result_builder
+            ignored_users: Set of users ignored by user.
+            room_builder
+            ephemeral: List of new ephemeral events for room
+            tags: List of *all* tags for room, or None if there has been
                 no change.
-            account_data(list): List of new account data for room
-            always_include(bool): Always include this room in the sync response,
+            account_data: List of new account data for room
+            always_include: Always include this room in the sync response,
                 even if empty.
         """
         newly_joined = room_builder.newly_joined
@@ -1760,12 +1798,12 @@ class SyncHandler(object):
         since_token = room_builder.since_token
         upto_token = room_builder.upto_token
 
-        batch = yield self._load_filtered_recents(
+        batch = await self._load_filtered_recents(
             room_id,
             sync_config,
             now_token=upto_token,
             since_token=since_token,
-            recents=events,
+            potential_recents=events,
             newly_joined_room=newly_joined,
         )
 
@@ -1787,7 +1825,7 @@ class SyncHandler(object):
         # tag was added by synapse e.g. for server notice rooms.
         if full_state:
             user_id = sync_result_builder.sync_config.user.to_string()
-            tags = yield self.store.get_tags_for_room(user_id, room_id)
+            tags = await self.store.get_tags_for_room(user_id, room_id)
 
             # If there aren't any tags, don't send the empty tags list down
             # sync
@@ -1812,11 +1850,11 @@ class SyncHandler(object):
         ):
             return
 
-        state = yield self.compute_state_delta(
+        state = await self.compute_state_delta(
             room_id, batch, sync_config, since_token, now_token, full_state=full_state
         )
 
-        summary = {}
+        summary = {}  # type: Optional[JsonDict]
 
         # we include a summary in room responses when we're lazy loading
         # members (as the client otherwise doesn't have enough info to form
@@ -1835,12 +1873,12 @@ class SyncHandler(object):
             )
             or since_token is None
         ):
-            summary = yield self.compute_summary(
+            summary = await self.compute_summary(
                 room_id, sync_config, batch, state, now_token
             )
 
         if room_builder.rtype == "joined":
-            unread_notifications = {}
+            unread_notifications = {}  # type: Dict[str, str]
             room_sync = JoinedSyncResult(
                 room_id=room_id,
                 timeline=batch,
@@ -1852,7 +1890,7 @@ class SyncHandler(object):
             )
 
             if room_sync or always_include:
-                notifs = yield self.unread_notifs_for_room_id(room_id, sync_config)
+                notifs = await self.unread_notifs_for_room_id(room_id, sync_config)
 
                 if notifs is not None:
                     unread_notifications["notification_count"] = notifs["notify_count"]
@@ -1862,24 +1900,25 @@ class SyncHandler(object):
 
             if batch.limited and since_token:
                 user_id = sync_result_builder.sync_config.user.to_string()
-                logger.info(
+                logger.debug(
                     "Incremental gappy sync of %s for user %s with %d state events"
                     % (room_id, user_id, len(state))
                 )
         elif room_builder.rtype == "archived":
-            room_sync = ArchivedSyncResult(
+            archived_room_sync = ArchivedSyncResult(
                 room_id=room_id,
                 timeline=batch,
                 state=state,
                 account_data=account_data_events,
             )
-            if room_sync or always_include:
-                sync_result_builder.archived.append(room_sync)
+            if archived_room_sync or always_include:
+                sync_result_builder.archived.append(archived_room_sync)
         else:
             raise Exception("Unrecognized rtype: %r", room_builder.rtype)
 
-    @defer.inlineCallbacks
-    def get_rooms_for_user_at(self, user_id, stream_ordering):
+    async def get_rooms_for_user_at(
+        self, user_id: str, stream_ordering: int
+    ) -> FrozenSet[str]:
         """Get set of joined rooms for a user at the given stream ordering.
 
         The stream ordering *must* be recent, otherwise this may throw an
@@ -1887,14 +1926,13 @@ class SyncHandler(object):
         current token, which should be perfectly fine).
 
         Args:
-            user_id (str)
-            stream_ordering (int)
+            user_id
+            stream_ordering
 
         ReturnValue:
-            Deferred[frozenset[str]]: Set of room_ids the user is in at given
-            stream_ordering.
+            Set of room_ids the user is in at given stream_ordering.
         """
-        joined_rooms = yield self.store.get_rooms_for_user_with_stream_ordering(user_id)
+        joined_rooms = await self.store.get_rooms_for_user_with_stream_ordering(user_id)
 
         joined_room_ids = set()
 
@@ -1912,18 +1950,17 @@ class SyncHandler(object):
 
             logger.info("User joined room after current token: %s", room_id)
 
-            extrems = yield self.store.get_forward_extremeties_for_room(
+            extrems = await self.store.get_forward_extremeties_for_room(
                 room_id, stream_ordering
             )
-            users_in_room = yield self.state.get_current_users_in_room(room_id, extrems)
+            users_in_room = await self.state.get_current_users_in_room(room_id, extrems)
             if user_id in users_in_room:
                 joined_room_ids.add(room_id)
 
-        joined_room_ids = frozenset(joined_room_ids)
-        return joined_room_ids
+        return frozenset(joined_room_ids)
 
 
-def _action_has_highlight(actions):
+def _action_has_highlight(actions: List[JsonDict]) -> bool:
     for action in actions:
         try:
             if action.get("set_tweak", None) == "highlight":
@@ -1935,22 +1972,23 @@ def _action_has_highlight(actions):
 
 
 def _calculate_state(
-    timeline_contains, timeline_start, previous, current, lazy_load_members
-):
+    timeline_contains: StateMap[str],
+    timeline_start: StateMap[str],
+    previous: StateMap[str],
+    current: StateMap[str],
+    lazy_load_members: bool,
+) -> StateMap[str]:
     """Works out what state to include in a sync response.
 
     Args:
-        timeline_contains (dict): state in the timeline
-        timeline_start (dict): state at the start of the timeline
-        previous (dict): state at the end of the previous sync (or empty dict
+        timeline_contains: state in the timeline
+        timeline_start: state at the start of the timeline
+        previous: state at the end of the previous sync (or empty dict
             if this is an initial sync)
-        current (dict): state at the end of the timeline
-        lazy_load_members (bool): whether to return members from timeline_start
+        current: state at the end of the timeline
+        lazy_load_members: whether to return members from timeline_start
             or not.  assumes that timeline_start has already been filtered to
             include only the members the client needs to know about.
-
-    Returns:
-        dict
     """
     event_id_to_key = {
         e: key
@@ -1962,10 +2000,10 @@ def _calculate_state(
         )
     }
 
-    c_ids = set(e for e in itervalues(current))
-    ts_ids = set(e for e in itervalues(timeline_start))
-    p_ids = set(e for e in itervalues(previous))
-    tc_ids = set(e for e in itervalues(timeline_contains))
+    c_ids = set(itervalues(current))
+    ts_ids = set(itervalues(timeline_start))
+    p_ids = set(itervalues(previous))
+    tc_ids = set(itervalues(timeline_contains))
 
     # If we are lazyloading room members, we explicitly add the membership events
     # for the senders in the timeline into the state block returned by /sync,
@@ -1987,15 +2025,16 @@ def _calculate_state(
     return {event_id_to_key[e]: e for e in state_ids}
 
 
-class SyncResultBuilder(object):
+@attr.s
+class SyncResultBuilder:
     """Used to help build up a new SyncResult for a user
 
     Attributes:
-        sync_config (SyncConfig)
-        full_state (bool)
-        since_token (StreamToken)
-        now_token (StreamToken)
-        joined_room_ids (list[str])
+        sync_config
+        full_state: The full_state flag as specified by user
+        since_token: The token supplied by user, or None.
+        now_token: The token to sync up to.
+        joined_room_ids: List of rooms the user is joined to
 
         # The following mirror the fields in a sync response
         presence (list)
@@ -2003,61 +2042,45 @@ class SyncResultBuilder(object):
         joined (list[JoinedSyncResult])
         invited (list[InvitedSyncResult])
         archived (list[ArchivedSyncResult])
-        device (list)
         groups (GroupsSyncResult|None)
         to_device (list)
     """
 
-    def __init__(
-        self, sync_config, full_state, since_token, now_token, joined_room_ids
-    ):
-        """
-        Args:
-            sync_config (SyncConfig)
-            full_state (bool): The full_state flag as specified by user
-            since_token (StreamToken): The token supplied by user, or None.
-            now_token (StreamToken): The token to sync up to.
-            joined_room_ids (list[str]): List of rooms the user is joined to
-        """
-        self.sync_config = sync_config
-        self.full_state = full_state
-        self.since_token = since_token
-        self.now_token = now_token
-        self.joined_room_ids = joined_room_ids
-
-        self.presence = []
-        self.account_data = []
-        self.joined = []
-        self.invited = []
-        self.archived = []
-        self.device = []
-        self.groups = None
-        self.to_device = []
+    sync_config = attr.ib(type=SyncConfig)
+    full_state = attr.ib(type=bool)
+    since_token = attr.ib(type=Optional[StreamToken])
+    now_token = attr.ib(type=StreamToken)
+    joined_room_ids = attr.ib(type=FrozenSet[str])
+
+    presence = attr.ib(type=List[JsonDict], default=attr.Factory(list))
+    account_data = attr.ib(type=List[JsonDict], default=attr.Factory(list))
+    joined = attr.ib(type=List[JoinedSyncResult], default=attr.Factory(list))
+    invited = attr.ib(type=List[InvitedSyncResult], default=attr.Factory(list))
+    archived = attr.ib(type=List[ArchivedSyncResult], default=attr.Factory(list))
+    groups = attr.ib(type=Optional[GroupsSyncResult], default=None)
+    to_device = attr.ib(type=List[JsonDict], default=attr.Factory(list))
 
 
+@attr.s
 class RoomSyncResultBuilder(object):
     """Stores information needed to create either a `JoinedSyncResult` or
     `ArchivedSyncResult`.
+
+    Attributes:
+        room_id
+        rtype: One of `"joined"` or `"archived"`
+        events: List of events to include in the room (more events may be added
+            when generating result).
+        newly_joined: If the user has newly joined the room
+        full_state: Whether the full state should be sent in result
+        since_token: Earliest point to return events from, or None
+        upto_token: Latest point to return events from.
     """
 
-    def __init__(
-        self, room_id, rtype, events, newly_joined, full_state, since_token, upto_token
-    ):
-        """
-        Args:
-            room_id(str)
-            rtype(str): One of `"joined"` or `"archived"`
-            events(list[FrozenEvent]): List of events to include in the room
-                (more events may be added when generating result).
-            newly_joined(bool): If the user has newly joined the room
-            full_state(bool): Whether the full state should be sent in result
-            since_token(StreamToken): Earliest point to return events from, or None
-            upto_token(StreamToken): Latest point to return events from.
-        """
-        self.room_id = room_id
-        self.rtype = rtype
-        self.events = events
-        self.newly_joined = newly_joined
-        self.full_state = full_state
-        self.since_token = since_token
-        self.upto_token = upto_token
+    room_id = attr.ib(type=str)
+    rtype = attr.ib(type=str)
+    events = attr.ib(type=Optional[List[EventBase]])
+    newly_joined = attr.ib(type=bool)
+    full_state = attr.ib(type=bool)
+    since_token = attr.ib(type=Optional[StreamToken])
+    upto_token = attr.ib(type=StreamToken)
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index ca8ae9fb5b..c7bc14c623 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -15,6 +15,7 @@
 
 import logging
 from collections import namedtuple
+from typing import List
 
 from twisted.internet import defer
 
@@ -120,12 +121,12 @@ class TypingHandler(object):
         auth_user_id = auth_user.to_string()
 
         if not self.is_mine_id(target_user_id):
-            raise SynapseError(400, "User is not hosted on this Home Server")
+            raise SynapseError(400, "User is not hosted on this homeserver")
 
         if target_user_id != auth_user_id:
             raise AuthError(400, "Cannot set another user's typing state")
 
-        yield self.auth.check_joined_room(room_id, target_user_id)
+        yield self.auth.check_user_in_room(room_id, target_user_id)
 
         logger.debug("%s has started typing in %s", target_user_id, room_id)
 
@@ -150,12 +151,12 @@ class TypingHandler(object):
         auth_user_id = auth_user.to_string()
 
         if not self.is_mine_id(target_user_id):
-            raise SynapseError(400, "User is not hosted on this Home Server")
+            raise SynapseError(400, "User is not hosted on this homeserver")
 
         if target_user_id != auth_user_id:
             raise AuthError(400, "Cannot set another user's typing state")
 
-        yield self.auth.check_joined_room(room_id, target_user_id)
+        yield self.auth.check_user_in_room(room_id, target_user_id)
 
         logger.debug("%s has stopped typing in %s", target_user_id, room_id)
 
@@ -198,7 +199,7 @@ class TypingHandler(object):
                 now=now, obj=member, then=now + FEDERATION_PING_INTERVAL
             )
 
-            for domain in set(get_domain_from_id(u) for u in users):
+            for domain in {get_domain_from_id(u) for u in users}:
                 if domain != self.server_name:
                     logger.debug("sending typing update to %s", domain)
                     self.federation.build_and_send_edu(
@@ -231,7 +232,7 @@ class TypingHandler(object):
             return
 
         users = yield self.state.get_current_users_in_room(room_id)
-        domains = set(get_domain_from_id(u) for u in users)
+        domains = {get_domain_from_id(u) for u in users}
 
         if self.server_name in domains:
             logger.info("Got typing update from %s: %r", user_id, content)
@@ -257,7 +258,13 @@ class TypingHandler(object):
             "typing_key", self._latest_room_serial, rooms=[member.room_id]
         )
 
-    def get_all_typing_updates(self, last_id, current_id):
+    async def get_all_typing_updates(
+        self, last_id: int, current_id: int, limit: int
+    ) -> List[dict]:
+        """Get up to `limit` typing updates between the given tokens, earliest
+        updates first.
+        """
+
         if last_id == current_id:
             return []
 
@@ -275,7 +282,7 @@ class TypingHandler(object):
                 typing = self._room_typing[room_id]
                 rows.append((serial, room_id, list(typing)))
         rows.sort()
-        return rows
+        return rows[:limit]
 
     def get_current_token(self):
         return self._latest_room_serial
@@ -313,10 +320,7 @@ class TypingNotificationEventSource(object):
 
                 events.append(self._make_event_for(room_id))
 
-            return events, handler._latest_room_serial
+            return defer.succeed((events, handler._latest_room_serial))
 
     def get_current_key(self):
         return self.get_typing_handler()._latest_room_serial
-
-    def get_pagination_rows(self, user, pagination_config, key):
-        return [], pagination_config.from_key
diff --git a/synapse/handlers/ui_auth/__init__.py b/synapse/handlers/ui_auth/__init__.py
new file mode 100644
index 0000000000..824f37f8f8
--- /dev/null
+++ b/synapse/handlers/ui_auth/__init__.py
@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""This module implements user-interactive auth verification.
+
+TODO: move more stuff out of AuthHandler in here.
+
+"""
+
+from synapse.handlers.ui_auth.checkers import INTERACTIVE_AUTH_CHECKERS  # noqa: F401
diff --git a/synapse/handlers/ui_auth/checkers.py b/synapse/handlers/ui_auth/checkers.py
new file mode 100644
index 0000000000..8b24a73319
--- /dev/null
+++ b/synapse/handlers/ui_auth/checkers.py
@@ -0,0 +1,246 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import logging
+
+from canonicaljson import json
+
+from twisted.internet import defer
+from twisted.web.client import PartialDownloadError
+
+from synapse.api.constants import LoginType
+from synapse.api.errors import Codes, LoginError, SynapseError
+from synapse.config.emailconfig import ThreepidBehaviour
+
+logger = logging.getLogger(__name__)
+
+
+class UserInteractiveAuthChecker:
+    """Abstract base class for an interactive auth checker"""
+
+    def __init__(self, hs):
+        pass
+
+    def is_enabled(self):
+        """Check if the configuration of the homeserver allows this checker to work
+
+        Returns:
+            bool: True if this login type is enabled.
+        """
+
+    def check_auth(self, authdict, clientip):
+        """Given the authentication dict from the client, attempt to check this step
+
+        Args:
+            authdict (dict): authentication dictionary from the client
+            clientip (str): The IP address of the client.
+
+        Raises:
+            SynapseError if authentication failed
+
+        Returns:
+            Deferred: the result of authentication (to pass back to the client?)
+        """
+        raise NotImplementedError()
+
+
+class DummyAuthChecker(UserInteractiveAuthChecker):
+    AUTH_TYPE = LoginType.DUMMY
+
+    def is_enabled(self):
+        return True
+
+    def check_auth(self, authdict, clientip):
+        return defer.succeed(True)
+
+
+class TermsAuthChecker(UserInteractiveAuthChecker):
+    AUTH_TYPE = LoginType.TERMS
+
+    def is_enabled(self):
+        return True
+
+    def check_auth(self, authdict, clientip):
+        return defer.succeed(True)
+
+
+class RecaptchaAuthChecker(UserInteractiveAuthChecker):
+    AUTH_TYPE = LoginType.RECAPTCHA
+
+    def __init__(self, hs):
+        super().__init__(hs)
+        self._enabled = bool(hs.config.recaptcha_private_key)
+        self._http_client = hs.get_proxied_http_client()
+        self._url = hs.config.recaptcha_siteverify_api
+        self._secret = hs.config.recaptcha_private_key
+
+    def is_enabled(self):
+        return self._enabled
+
+    @defer.inlineCallbacks
+    def check_auth(self, authdict, clientip):
+        try:
+            user_response = authdict["response"]
+        except KeyError:
+            # Client tried to provide captcha but didn't give the parameter:
+            # bad request.
+            raise LoginError(
+                400, "Captcha response is required", errcode=Codes.CAPTCHA_NEEDED
+            )
+
+        logger.info(
+            "Submitting recaptcha response %s with remoteip %s", user_response, clientip
+        )
+
+        # TODO: get this from the homeserver rather than creating a new one for
+        # each request
+        try:
+            resp_body = yield self._http_client.post_urlencoded_get_json(
+                self._url,
+                args={
+                    "secret": self._secret,
+                    "response": user_response,
+                    "remoteip": clientip,
+                },
+            )
+        except PartialDownloadError as pde:
+            # Twisted is silly
+            data = pde.response
+            resp_body = json.loads(data)
+
+        if "success" in resp_body:
+            # Note that we do NOT check the hostname here: we explicitly
+            # intend the CAPTCHA to be presented by whatever client the
+            # user is using, we just care that they have completed a CAPTCHA.
+            logger.info(
+                "%s reCAPTCHA from hostname %s",
+                "Successful" if resp_body["success"] else "Failed",
+                resp_body.get("hostname"),
+            )
+            if resp_body["success"]:
+                return True
+        raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)
+
+
+class _BaseThreepidAuthChecker:
+    def __init__(self, hs):
+        self.hs = hs
+        self.store = hs.get_datastore()
+
+    async def _check_threepid(self, medium, authdict):
+        if "threepid_creds" not in authdict:
+            raise LoginError(400, "Missing threepid_creds", Codes.MISSING_PARAM)
+
+        threepid_creds = authdict["threepid_creds"]
+
+        identity_handler = self.hs.get_handlers().identity_handler
+
+        logger.info("Getting validated threepid. threepidcreds: %r", (threepid_creds,))
+
+        # msisdns are currently always ThreepidBehaviour.REMOTE
+        if medium == "msisdn":
+            if not self.hs.config.account_threepid_delegate_msisdn:
+                raise SynapseError(
+                    400, "Phone number verification is not enabled on this homeserver"
+                )
+            threepid = await identity_handler.threepid_from_creds(
+                self.hs.config.account_threepid_delegate_msisdn, threepid_creds
+            )
+        elif medium == "email":
+            if self.hs.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+                assert self.hs.config.account_threepid_delegate_email
+                threepid = await identity_handler.threepid_from_creds(
+                    self.hs.config.account_threepid_delegate_email, threepid_creds
+                )
+            elif self.hs.config.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
+                threepid = None
+                row = await self.store.get_threepid_validation_session(
+                    medium,
+                    threepid_creds["client_secret"],
+                    sid=threepid_creds["sid"],
+                    validated=True,
+                )
+
+                if row:
+                    threepid = {
+                        "medium": row["medium"],
+                        "address": row["address"],
+                        "validated_at": row["validated_at"],
+                    }
+
+                    # Valid threepid returned, delete from the db
+                    await self.store.delete_threepid_session(threepid_creds["sid"])
+            else:
+                raise SynapseError(
+                    400, "Email address verification is not enabled on this homeserver"
+                )
+        else:
+            # this can't happen!
+            raise AssertionError("Unrecognized threepid medium: %s" % (medium,))
+
+        if not threepid:
+            raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)
+
+        if threepid["medium"] != medium:
+            raise LoginError(
+                401,
+                "Expecting threepid of type '%s', got '%s'"
+                % (medium, threepid["medium"]),
+                errcode=Codes.UNAUTHORIZED,
+            )
+
+        threepid["threepid_creds"] = authdict["threepid_creds"]
+
+        return threepid
+
+
+class EmailIdentityAuthChecker(UserInteractiveAuthChecker, _BaseThreepidAuthChecker):
+    AUTH_TYPE = LoginType.EMAIL_IDENTITY
+
+    def __init__(self, hs):
+        UserInteractiveAuthChecker.__init__(self, hs)
+        _BaseThreepidAuthChecker.__init__(self, hs)
+
+    def is_enabled(self):
+        return self.hs.config.threepid_behaviour_email in (
+            ThreepidBehaviour.REMOTE,
+            ThreepidBehaviour.LOCAL,
+        )
+
+    def check_auth(self, authdict, clientip):
+        return defer.ensureDeferred(self._check_threepid("email", authdict))
+
+
+class MsisdnAuthChecker(UserInteractiveAuthChecker, _BaseThreepidAuthChecker):
+    AUTH_TYPE = LoginType.MSISDN
+
+    def __init__(self, hs):
+        UserInteractiveAuthChecker.__init__(self, hs)
+        _BaseThreepidAuthChecker.__init__(self, hs)
+
+    def is_enabled(self):
+        return bool(self.hs.config.account_threepid_delegate_msisdn)
+
+    def check_auth(self, authdict, clientip):
+        return defer.ensureDeferred(self._check_threepid("msisdn", authdict))
+
+
+INTERACTIVE_AUTH_CHECKERS = [
+    DummyAuthChecker,
+    TermsAuthChecker,
+    RecaptchaAuthChecker,
+    EmailIdentityAuthChecker,
+    MsisdnAuthChecker,
+]
+"""A list of UserInteractiveAuthChecker classes"""
diff --git a/synapse/handlers/user_directory.py b/synapse/handlers/user_directory.py
index e53669e40d..12423b909a 100644
--- a/synapse/handlers/user_directory.py
+++ b/synapse/handlers/user_directory.py
@@ -17,14 +17,11 @@ import logging
 
 from six import iteritems, iterkeys
 
-from twisted.internet import defer
-
 import synapse.metrics
 from synapse.api.constants import EventTypes, JoinRules, Membership
 from synapse.handlers.state_deltas import StateDeltasHandler
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage.roommember import ProfileInfo
-from synapse.types import get_localpart_from_id
 from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
@@ -52,6 +49,7 @@ class UserDirectoryHandler(StateDeltasHandler):
         self.is_mine_id = hs.is_mine_id
         self.update_user_directory = hs.config.update_user_directory
         self.search_all_users = hs.config.user_directory_search_all_users
+        self.spam_checker = hs.get_spam_checker()
         # The current position in the current_state_delta stream
         self.pos = None
 
@@ -65,7 +63,7 @@ class UserDirectoryHandler(StateDeltasHandler):
             # we start populating the user directory
             self.clock.call_later(0, self.notify_new_event)
 
-    def search_users(self, user_id, search_term, limit):
+    async def search_users(self, user_id, search_term, limit):
         """Searches for users in directory
 
         Returns:
@@ -82,7 +80,16 @@ class UserDirectoryHandler(StateDeltasHandler):
                     ]
                 }
         """
-        return self.store.search_user_dir(user_id, search_term, limit)
+        results = await self.store.search_user_dir(user_id, search_term, limit)
+
+        # Remove any spammy users from the results.
+        results["results"] = [
+            user
+            for user in results["results"]
+            if not self.spam_checker.check_username_for_spam(user)
+        ]
+
+        return results
 
     def notify_new_event(self):
         """Called when there may be more deltas to process
@@ -93,43 +100,39 @@ class UserDirectoryHandler(StateDeltasHandler):
         if self._is_processing:
             return
 
-        @defer.inlineCallbacks
-        def process():
+        async def process():
             try:
-                yield self._unsafe_process()
+                await self._unsafe_process()
             finally:
                 self._is_processing = False
 
         self._is_processing = True
         run_as_background_process("user_directory.notify_new_event", process)
 
-    @defer.inlineCallbacks
-    def handle_local_profile_change(self, user_id, profile):
+    async def handle_local_profile_change(self, user_id, profile):
         """Called to update index of our local user profiles when they change
         irrespective of any rooms the user may be in.
         """
         # FIXME(#3714): We should probably do this in the same worker as all
         # the other changes.
-        is_support = yield self.store.is_support_user(user_id)
+        is_support = await self.store.is_support_user(user_id)
         # Support users are for diagnostics and should not appear in the user directory.
         if not is_support:
-            yield self.store.update_profile_in_user_dir(
+            await self.store.update_profile_in_user_dir(
                 user_id, profile.display_name, profile.avatar_url
             )
 
-    @defer.inlineCallbacks
-    def handle_user_deactivated(self, user_id):
+    async def handle_user_deactivated(self, user_id):
         """Called when a user ID is deactivated
         """
         # FIXME(#3714): We should probably do this in the same worker as all
         # the other changes.
-        yield self.store.remove_from_user_dir(user_id)
+        await self.store.remove_from_user_dir(user_id)
 
-    @defer.inlineCallbacks
-    def _unsafe_process(self):
+    async def _unsafe_process(self):
         # If self.pos is None then means we haven't fetched it from DB
         if self.pos is None:
-            self.pos = yield self.store.get_user_directory_stream_pos()
+            self.pos = await self.store.get_user_directory_stream_pos()
 
         # If still None then the initial background update hasn't happened yet
         if self.pos is None:
@@ -138,24 +141,30 @@ class UserDirectoryHandler(StateDeltasHandler):
         # Loop round handling deltas until we're up to date
         while True:
             with Measure(self.clock, "user_dir_delta"):
-                deltas = yield self.store.get_current_state_deltas(self.pos)
-                if not deltas:
+                room_max_stream_ordering = self.store.get_room_max_stream_ordering()
+                if self.pos == room_max_stream_ordering:
                     return
 
-                logger.info("Handling %d state deltas", len(deltas))
-                yield self._handle_deltas(deltas)
+                logger.debug(
+                    "Processing user stats %s->%s", self.pos, room_max_stream_ordering
+                )
+                max_pos, deltas = await self.store.get_current_state_deltas(
+                    self.pos, room_max_stream_ordering
+                )
+
+                logger.debug("Handling %d state deltas", len(deltas))
+                await self._handle_deltas(deltas)
 
-                self.pos = deltas[-1]["stream_id"]
+                self.pos = max_pos
 
                 # Expose current event processing position to prometheus
                 synapse.metrics.event_processing_positions.labels("user_dir").set(
-                    self.pos
+                    max_pos
                 )
 
-                yield self.store.update_user_directory_stream_pos(self.pos)
+                await self.store.update_user_directory_stream_pos(max_pos)
 
-    @defer.inlineCallbacks
-    def _handle_deltas(self, deltas):
+    async def _handle_deltas(self, deltas):
         """Called with the state deltas to process
         """
         for delta in deltas:
@@ -170,11 +179,11 @@ class UserDirectoryHandler(StateDeltasHandler):
             # For join rule and visibility changes we need to check if the room
             # may have become public or not and add/remove the users in said room
             if typ in (EventTypes.RoomHistoryVisibility, EventTypes.JoinRules):
-                yield self._handle_room_publicity_change(
+                await self._handle_room_publicity_change(
                     room_id, prev_event_id, event_id, typ
                 )
             elif typ == EventTypes.Member:
-                change = yield self._get_key_change(
+                change = await self._get_key_change(
                     prev_event_id,
                     event_id,
                     key_name="membership",
@@ -184,48 +193,49 @@ class UserDirectoryHandler(StateDeltasHandler):
                 if change is False:
                     # Need to check if the server left the room entirely, if so
                     # we might need to remove all the users in that room
-                    is_in_room = yield self.store.is_host_joined(
+                    is_in_room = await self.store.is_host_joined(
                         room_id, self.server_name
                     )
                     if not is_in_room:
-                        logger.info("Server left room: %r", room_id)
+                        logger.debug("Server left room: %r", room_id)
                         # Fetch all the users that we marked as being in user
                         # directory due to being in the room and then check if
                         # need to remove those users or not
-                        user_ids = yield self.store.get_users_in_dir_due_to_room(
+                        user_ids = await self.store.get_users_in_dir_due_to_room(
                             room_id
                         )
 
                         for user_id in user_ids:
-                            yield self._handle_remove_user(room_id, user_id)
+                            await self._handle_remove_user(room_id, user_id)
                         return
                     else:
                         logger.debug("Server is still in room: %r", room_id)
 
-                is_support = yield self.store.is_support_user(state_key)
+                is_support = await self.store.is_support_user(state_key)
                 if not is_support:
                     if change is None:
                         # Handle any profile changes
-                        yield self._handle_profile_change(
+                        await self._handle_profile_change(
                             state_key, room_id, prev_event_id, event_id
                         )
                         continue
 
                     if change:  # The user joined
-                        event = yield self.store.get_event(event_id, allow_none=True)
+                        event = await self.store.get_event(event_id, allow_none=True)
                         profile = ProfileInfo(
                             avatar_url=event.content.get("avatar_url"),
                             display_name=event.content.get("displayname"),
                         )
 
-                        yield self._handle_new_user(room_id, state_key, profile)
+                        await self._handle_new_user(room_id, state_key, profile)
                     else:  # The user left
-                        yield self._handle_remove_user(room_id, state_key)
+                        await self._handle_remove_user(room_id, state_key)
             else:
                 logger.debug("Ignoring irrelevant type: %r", typ)
 
-    @defer.inlineCallbacks
-    def _handle_room_publicity_change(self, room_id, prev_event_id, event_id, typ):
+    async def _handle_room_publicity_change(
+        self, room_id, prev_event_id, event_id, typ
+    ):
         """Handle a room having potentially changed from/to world_readable/publically
         joinable.
 
@@ -238,14 +248,14 @@ class UserDirectoryHandler(StateDeltasHandler):
         logger.debug("Handling change for %s: %s", typ, room_id)
 
         if typ == EventTypes.RoomHistoryVisibility:
-            change = yield self._get_key_change(
+            change = await self._get_key_change(
                 prev_event_id,
                 event_id,
                 key_name="history_visibility",
                 public_value="world_readable",
             )
         elif typ == EventTypes.JoinRules:
-            change = yield self._get_key_change(
+            change = await self._get_key_change(
                 prev_event_id,
                 event_id,
                 key_name="join_rule",
@@ -261,7 +271,7 @@ class UserDirectoryHandler(StateDeltasHandler):
 
         # There's been a change to or from being world readable.
 
-        is_public = yield self.store.is_room_world_readable_or_publicly_joinable(
+        is_public = await self.store.is_room_world_readable_or_publicly_joinable(
             room_id
         )
 
@@ -276,11 +286,11 @@ class UserDirectoryHandler(StateDeltasHandler):
             # ignore the change
             return
 
-        users_with_profile = yield self.state.get_current_users_in_room(room_id)
+        users_with_profile = await self.state.get_current_users_in_room(room_id)
 
         # Remove every user from the sharing tables for that room.
         for user_id in iterkeys(users_with_profile):
-            yield self.store.remove_user_who_share_room(user_id, room_id)
+            await self.store.remove_user_who_share_room(user_id, room_id)
 
         # Then, re-add them to the tables.
         # NOTE: this is not the most efficient method, as handle_new_user sets
@@ -289,26 +299,9 @@ class UserDirectoryHandler(StateDeltasHandler):
         # being added multiple times. The batching upserts shouldn't make this
         # too bad, though.
         for user_id, profile in iteritems(users_with_profile):
-            yield self._handle_new_user(room_id, user_id, profile)
-
-    @defer.inlineCallbacks
-    def _handle_local_user(self, user_id):
-        """Adds a new local roomless user into the user_directory_search table.
-        Used to populate up the user index when we have an
-        user_directory_search_all_users specified.
-        """
-        logger.debug("Adding new local user to dir, %r", user_id)
-
-        profile = yield self.store.get_profileinfo(get_localpart_from_id(user_id))
-
-        row = yield self.store.get_user_in_directory(user_id)
-        if not row:
-            yield self.store.update_profile_in_user_dir(
-                user_id, profile.display_name, profile.avatar_url
-            )
+            await self._handle_new_user(room_id, user_id, profile)
 
-    @defer.inlineCallbacks
-    def _handle_new_user(self, room_id, user_id, profile):
+    async def _handle_new_user(self, room_id, user_id, profile):
         """Called when we might need to add user to directory
 
         Args:
@@ -317,18 +310,18 @@ class UserDirectoryHandler(StateDeltasHandler):
         """
         logger.debug("Adding new user to dir, %r", user_id)
 
-        yield self.store.update_profile_in_user_dir(
+        await self.store.update_profile_in_user_dir(
             user_id, profile.display_name, profile.avatar_url
         )
 
-        is_public = yield self.store.is_room_world_readable_or_publicly_joinable(
+        is_public = await self.store.is_room_world_readable_or_publicly_joinable(
             room_id
         )
         # Now we update users who share rooms with users.
-        users_with_profile = yield self.state.get_current_users_in_room(room_id)
+        users_with_profile = await self.state.get_current_users_in_room(room_id)
 
         if is_public:
-            yield self.store.add_users_in_public_rooms(room_id, (user_id,))
+            await self.store.add_users_in_public_rooms(room_id, (user_id,))
         else:
             to_insert = set()
 
@@ -359,10 +352,9 @@ class UserDirectoryHandler(StateDeltasHandler):
                     to_insert.add((other_user_id, user_id))
 
             if to_insert:
-                yield self.store.add_users_who_share_private_room(room_id, to_insert)
+                await self.store.add_users_who_share_private_room(room_id, to_insert)
 
-    @defer.inlineCallbacks
-    def _handle_remove_user(self, room_id, user_id):
+    async def _handle_remove_user(self, room_id, user_id):
         """Called when we might need to remove user from directory
 
         Args:
@@ -372,24 +364,23 @@ class UserDirectoryHandler(StateDeltasHandler):
         logger.debug("Removing user %r", user_id)
 
         # Remove user from sharing tables
-        yield self.store.remove_user_who_share_room(user_id, room_id)
+        await self.store.remove_user_who_share_room(user_id, room_id)
 
         # Are they still in any rooms? If not, remove them entirely.
-        rooms_user_is_in = yield self.store.get_user_dir_rooms_user_is_in(user_id)
+        rooms_user_is_in = await self.store.get_user_dir_rooms_user_is_in(user_id)
 
         if len(rooms_user_is_in) == 0:
-            yield self.store.remove_from_user_dir(user_id)
+            await self.store.remove_from_user_dir(user_id)
 
-    @defer.inlineCallbacks
-    def _handle_profile_change(self, user_id, room_id, prev_event_id, event_id):
+    async def _handle_profile_change(self, user_id, room_id, prev_event_id, event_id):
         """Check member event changes for any profile changes and update the
         database if there are.
         """
         if not prev_event_id or not event_id:
             return
 
-        prev_event = yield self.store.get_event(prev_event_id, allow_none=True)
-        event = yield self.store.get_event(event_id, allow_none=True)
+        prev_event = await self.store.get_event(prev_event_id, allow_none=True)
+        event = await self.store.get_event(event_id, allow_none=True)
 
         if not prev_event or not event:
             return
@@ -404,4 +395,4 @@ class UserDirectoryHandler(StateDeltasHandler):
         new_avatar = event.content.get("avatar_url")
 
         if prev_name != new_name or prev_avatar != new_avatar:
-            yield self.store.update_profile_in_user_dir(user_id, new_name, new_avatar)
+            await self.store.update_profile_in_user_dir(user_id, new_name, new_avatar)