Merge pull request #679 from matrix-org/erikj/member

Split out RoomMemberHandler

3 files changed, 651 insertions, 603 deletions

diff --git a/synapse/handlers/__init__.py b/synapse/handlers/__init__.py
index 66d2c01123..f4dbf47c1d 100644
--- a/synapse/handlers/__init__.py
+++ b/synapse/handlers/__init__.py
@@ -17,8 +17,9 @@ from synapse.appservice.scheduler import AppServiceScheduler
 from synapse.appservice.api import ApplicationServiceApi
 from .register import RegistrationHandler
 from .room import (
-    RoomCreationHandler, RoomMemberHandler, RoomListHandler, RoomContextHandler,
+    RoomCreationHandler, RoomListHandler, RoomContextHandler,
 )
+from .room_member import RoomMemberHandler
 from .message import MessageHandler
 from .events import EventStreamHandler, EventHandler
 from .federation import FederationHandler
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index a230dc37f2..ee99ded214 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -18,20 +18,16 @@ from twisted.internet import defer
 
 from ._base import BaseHandler
 
-from synapse.types import UserID, RoomAlias, RoomID, RoomStreamToken, Requester
+from synapse.types import UserID, RoomAlias, RoomID, RoomStreamToken
 from synapse.api.constants import (
-    EventTypes, Membership, JoinRules, RoomCreationPreset,
+    EventTypes, JoinRules, RoomCreationPreset,
 )
-from synapse.api.errors import AuthError, StoreError, SynapseError, Codes
+from synapse.api.errors import AuthError, StoreError, SynapseError
 from synapse.util import stringutils, unwrapFirstError
 from synapse.util.logcontext import preserve_context_over_fn
 from synapse.util.caches.response_cache import ResponseCache
 
-from signedjson.sign import verify_signed_json
-from signedjson.key import decode_verify_key_bytes
-
 from collections import OrderedDict
-from unpaddedbase64 import decode_base64
 
 import logging
 import math
@@ -357,601 +353,6 @@ class RoomCreationHandler(BaseHandler):
             )
 
 
-class RoomMemberHandler(BaseHandler):
-    # TODO(paul): This handler currently contains a messy conflation of
-    #   low-level API that works on UserID objects and so on, and REST-level
-    #   API that takes ID strings and returns pagination chunks. These concerns
-    #   ought to be separated out a lot better.
-
-    def __init__(self, hs):
-        super(RoomMemberHandler, self).__init__(hs)
-
-        self.clock = hs.get_clock()
-
-        self.distributor = hs.get_distributor()
-        self.distributor.declare("user_joined_room")
-        self.distributor.declare("user_left_room")
-
-    @defer.inlineCallbacks
-    def get_room_members(self, room_id):
-        users = yield self.store.get_users_in_room(room_id)
-
-        defer.returnValue([UserID.from_string(u) for u in users])
-
-    @defer.inlineCallbacks
-    def fetch_room_distributions_into(self, room_id, localusers=None,
-                                      remotedomains=None, ignore_user=None):
-        """Fetch the distribution of a room, adding elements to either
-        'localusers' or 'remotedomains', which should be a set() if supplied.
-        If ignore_user is set, ignore that user.
-
-        This function returns nothing; its result is performed by the
-        side-effect on the two passed sets. This allows easy accumulation of
-        member lists of multiple rooms at once if required.
-        """
-        members = yield self.get_room_members(room_id)
-        for member in members:
-            if ignore_user is not None and member == ignore_user:
-                continue
-
-            if self.hs.is_mine(member):
-                if localusers is not None:
-                    localusers.add(member)
-            else:
-                if remotedomains is not None:
-                    remotedomains.add(member.domain)
-
-    @defer.inlineCallbacks
-    def update_membership(
-            self,
-            requester,
-            target,
-            room_id,
-            action,
-            txn_id=None,
-            remote_room_hosts=None,
-            third_party_signed=None,
-            ratelimit=True,
-    ):
-        effective_membership_state = action
-        if action in ["kick", "unban"]:
-            effective_membership_state = "leave"
-
-        if third_party_signed is not None:
-            replication = self.hs.get_replication_layer()
-            yield replication.exchange_third_party_invite(
-                third_party_signed["sender"],
-                target.to_string(),
-                room_id,
-                third_party_signed,
-            )
-
-        msg_handler = self.hs.get_handlers().message_handler
-
-        content = {"membership": effective_membership_state}
-        if requester.is_guest:
-            content["kind"] = "guest"
-
-        event, context = yield msg_handler.create_event(
-            {
-                "type": EventTypes.Member,
-                "content": content,
-                "room_id": room_id,
-                "sender": requester.user.to_string(),
-                "state_key": target.to_string(),
-
-                # For backwards compatibility:
-                "membership": effective_membership_state,
-            },
-            token_id=requester.access_token_id,
-            txn_id=txn_id,
-        )
-
-        old_state = context.current_state.get((EventTypes.Member, event.state_key))
-        old_membership = old_state.content.get("membership") if old_state else None
-        if action == "unban" and old_membership != "ban":
-            raise SynapseError(
-                403,
-                "Cannot unban user who was not banned (membership=%s)" % old_membership,
-                errcode=Codes.BAD_STATE
-            )
-        if old_membership == "ban" and action != "unban":
-            raise SynapseError(
-                403,
-                "Cannot %s user who was is banned" % (action,),
-                errcode=Codes.BAD_STATE
-            )
-
-        member_handler = self.hs.get_handlers().room_member_handler
-        yield member_handler.send_membership_event(
-            requester,
-            event,
-            context,
-            ratelimit=ratelimit,
-            remote_room_hosts=remote_room_hosts,
-        )
-
-    @defer.inlineCallbacks
-    def send_membership_event(
-            self,
-            requester,
-            event,
-            context,
-            remote_room_hosts=None,
-            ratelimit=True,
-    ):
-        """
-        Change the membership status of a user in a room.
-
-        Args:
-            requester (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.
-            context: The context of the event.
-            is_guest (bool): Whether the sender is a guest.
-            room_hosts ([str]): Homeservers which are likely to already be in
-                the room, and could be danced with in order to join this
-                homeserver for the first time.
-            ratelimit (bool): Whether to rate limit this request.
-        Raises:
-            SynapseError if there was a problem changing the membership.
-        """
-        remote_room_hosts = remote_room_hosts or []
-
-        target_user = UserID.from_string(event.state_key)
-        room_id = event.room_id
-
-        if requester is not None:
-            sender = UserID.from_string(event.sender)
-            assert sender == requester.user, (
-                "Sender (%s) must be same as requester (%s)" %
-                (sender, requester.user)
-            )
-            assert self.hs.is_mine(sender), "Sender must be our own: %s" % (sender,)
-        else:
-            requester = Requester(target_user, None, False)
-
-        message_handler = self.hs.get_handlers().message_handler
-        prev_event = message_handler.deduplicate_state_event(event, context)
-        if prev_event is not None:
-            return
-
-        action = "send"
-
-        if event.membership == Membership.JOIN:
-            if requester.is_guest and not self._can_guest_join(context.current_state):
-                # 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")
-            do_remote_join_dance, remote_room_hosts = self._should_do_dance(
-                context,
-                (self.get_inviter(event.state_key, context.current_state)),
-                remote_room_hosts,
-            )
-            if do_remote_join_dance:
-                action = "remote_join"
-        elif event.membership == Membership.LEAVE:
-            is_host_in_room = self.is_host_in_room(context.current_state)
-
-            if not is_host_in_room:
-                # perhaps we've been invited
-                inviter = self.get_inviter(
-                    target_user.to_string(), context.current_state
-                )
-                if not inviter:
-                    raise SynapseError(404, "Not a known room")
-
-                if self.hs.is_mine(inviter):
-                    # the inviter was on our server, but has now left. Carry on
-                    # with the normal rejection codepath.
-                    #
-                    # This is a bit of a hack, because the room might still be
-                    # active on other servers.
-                    pass
-                else:
-                    # send the rejection to the inviter's HS.
-                    remote_room_hosts = remote_room_hosts + [inviter.domain]
-                    action = "remote_reject"
-
-        federation_handler = self.hs.get_handlers().federation_handler
-
-        if action == "remote_join":
-            if len(remote_room_hosts) == 0:
-                raise SynapseError(404, "No known servers")
-
-            # We don't do an auth check if we are doing an invite
-            # 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 federation_handler.do_invite_join(
-                remote_room_hosts,
-                event.room_id,
-                event.user_id,
-                event.content,
-            )
-        elif action == "remote_reject":
-            yield federation_handler.do_remotely_reject_invite(
-                remote_room_hosts,
-                room_id,
-                event.user_id
-            )
-        else:
-            yield self.handle_new_client_event(
-                requester,
-                event,
-                context,
-                extra_users=[target_user],
-                ratelimit=ratelimit,
-            )
-
-        prev_member_event = context.current_state.get(
-            (EventTypes.Member, target_user.to_string()),
-            None
-        )
-
-        if event.membership == Membership.JOIN:
-            if not prev_member_event or prev_member_event.membership != Membership.JOIN:
-                # Only fire user_joined_room if the user has acutally joined the
-                # room. Don't bother if the user is just changing their profile
-                # info.
-                yield user_joined_room(self.distributor, target_user, room_id)
-        elif event.membership == Membership.LEAVE:
-            if prev_member_event and prev_member_event.membership == Membership.JOIN:
-                user_left_room(self.distributor, target_user, room_id)
-
-    def _can_guest_join(self, current_state):
-        """
-        Returns whether a guest can join a room based on its current state.
-        """
-        guest_access = current_state.get((EventTypes.GuestAccess, ""), None)
-        return (
-            guest_access
-            and guest_access.content
-            and "guest_access" in guest_access.content
-            and guest_access.content["guest_access"] == "can_join"
-        )
-
-    def _should_do_dance(self, context, inviter, room_hosts=None):
-        # TODO: Shouldn't this be remote_room_host?
-        room_hosts = room_hosts or []
-
-        is_host_in_room = self.is_host_in_room(context.current_state)
-        if is_host_in_room:
-            return False, room_hosts
-
-        if inviter and not self.hs.is_mine(inviter):
-            room_hosts.append(inviter.domain)
-
-        return True, room_hosts
-
-    @defer.inlineCallbacks
-    def lookup_room_alias(self, room_alias):
-        """
-        Get the room ID associated with a room alias.
-
-        Args:
-            room_alias (RoomAlias): The alias to look up.
-        Returns:
-            A tuple of:
-                The room ID as a RoomID object.
-                Hosts likely to be participating in the room ([str]).
-        Raises:
-            SynapseError if room alias could not be found.
-        """
-        directory_handler = self.hs.get_handlers().directory_handler
-        mapping = yield directory_handler.get_association(room_alias)
-
-        if not mapping:
-            raise SynapseError(404, "No such room alias")
-
-        room_id = mapping["room_id"]
-        servers = mapping["servers"]
-
-        defer.returnValue((RoomID.from_string(room_id), servers))
-
-    def get_inviter(self, user_id, current_state):
-        prev_state = current_state.get((EventTypes.Member, user_id))
-        if prev_state and prev_state.membership == Membership.INVITE:
-            return UserID.from_string(prev_state.user_id)
-        return None
-
-    @defer.inlineCallbacks
-    def get_joined_rooms_for_user(self, user):
-        """Returns a list of roomids that the user has any of the given
-        membership states in."""
-
-        rooms = yield self.store.get_rooms_for_user(
-            user.to_string(),
-        )
-
-        # For some reason the list of events contains duplicates
-        # TODO(paul): work out why because I really don't think it should
-        room_ids = set(r.room_id for r in rooms)
-
-        defer.returnValue(room_ids)
-
-    @defer.inlineCallbacks
-    def do_3pid_invite(
-            self,
-            room_id,
-            inviter,
-            medium,
-            address,
-            id_server,
-            requester,
-            txn_id
-    ):
-        invitee = yield self._lookup_3pid(
-            id_server, medium, address
-        )
-
-        if invitee:
-            handler = self.hs.get_handlers().room_member_handler
-            yield handler.update_membership(
-                requester,
-                UserID.from_string(invitee),
-                room_id,
-                "invite",
-                txn_id=txn_id,
-            )
-        else:
-            yield self._make_and_store_3pid_invite(
-                requester,
-                id_server,
-                medium,
-                address,
-                room_id,
-                inviter,
-                txn_id=txn_id
-            )
-
-    @defer.inlineCallbacks
-    def _lookup_3pid(self, id_server, medium, address):
-        """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").
-
-        Returns:
-            (str) the matrix ID of the 3pid, or None if it is not recognized.
-        """
-        try:
-            data = yield self.hs.get_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")
-                self.verify_any_signature(data, id_server)
-                defer.returnValue(data["mxid"])
-
-        except IOError as e:
-            logger.warn("Error from identity server lookup: %s" % (e,))
-            defer.returnValue(None)
-
-    @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.hs.get_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(
-            self,
-            requester,
-            id_server,
-            medium,
-            address,
-            room_id,
-            user,
-            txn_id
-    ):
-        room_state = yield self.hs.get_state_handler().get_current_state(room_id)
-
-        inviter_display_name = ""
-        inviter_avatar_url = ""
-        member_event = room_state.get((EventTypes.Member, user.to_string()))
-        if member_event:
-            inviter_display_name = member_event.content.get("displayname", "")
-            inviter_avatar_url = member_event.content.get("avatar_url", "")
-
-        canonical_room_alias = ""
-        canonical_alias_event = room_state.get((EventTypes.CanonicalAlias, ""))
-        if canonical_alias_event:
-            canonical_room_alias = canonical_alias_event.content.get("alias", "")
-
-        room_name = ""
-        room_name_event = room_state.get((EventTypes.Name, ""))
-        if room_name_event:
-            room_name = room_name_event.content.get("name", "")
-
-        room_join_rules = ""
-        join_rules_event = room_state.get((EventTypes.JoinRules, ""))
-        if join_rules_event:
-            room_join_rules = join_rules_event.content.get("join_rule", "")
-
-        room_avatar_url = ""
-        room_avatar_event = room_state.get((EventTypes.RoomAvatar, ""))
-        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(
-                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
-            )
-        )
-
-        msg_handler = self.hs.get_handlers().message_handler
-        yield msg_handler.create_and_send_nonmember_event(
-            requester,
-            {
-                "type": EventTypes.ThirdPartyInvite,
-                "content": {
-                    "display_name": display_name,
-                    "public_keys": public_keys,
-
-                    # For backwards compatibility:
-                    "key_validity_url": fallback_public_key["key_validity_url"],
-                    "public_key": fallback_public_key["public_key"],
-                },
-                "room_id": room_id,
-                "sender": user.to_string(),
-                "state_key": token,
-            },
-            txn_id=txn_id,
-        )
-
-    @defer.inlineCallbacks
-    def _ask_id_server_for_third_party_invite(
-            self,
-            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
-    ):
-        """
-        Asks an identity server for a third party invite.
-
-        :param id_server (str): hostname + optional port for the identity server.
-        :param medium (str): The literal string "email".
-        :param address (str): The third party address being invited.
-        :param room_id (str): The ID of the room to which the user is invited.
-        :param inviter_user_id (str): The user ID of the inviter.
-        :param room_alias (str): An alias for the room, for cosmetic
-            notifications.
-        :param room_avatar_url (str): The URL of the room's avatar, for cosmetic
-            notifications.
-        :param room_join_rules (str): The join rules of the email
-            (e.g. "public").
-        :param room_name (str): The m.room.name of the room.
-        :param inviter_display_name (str): The current display name of the
-            inviter.
-        :param inviter_avatar_url (str): The URL of the inviter's avatar.
-
-        :return: 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.
-        """
-
-        is_url = "%s%s/_matrix/identity/api/v1/store-invite" % (
-            id_server_scheme, id_server,
-        )
-
-        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,
-        }
-
-        if self.hs.config.invite_3pid_guest:
-            registration_handler = self.hs.get_handlers().registration_handler
-            guest_access_token = yield registration_handler.guest_access_token_for(
-                medium=medium,
-                address=address,
-                inviter_user_id=inviter_user_id,
-            )
-
-            guest_user_info = yield self.hs.get_auth().get_user_by_access_token(
-                guest_access_token
-            )
-
-            invite_config.update({
-                "guest_access_token": guest_access_token,
-                "guest_user_id": guest_user_info["user"].to_string(),
-            })
-
-        data = yield self.hs.get_simple_http_client().post_urlencoded_get_json(
-            is_url,
-            invite_config
-        )
-        # 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": "%s%s/_matrix/identity/api/v1/pubkey/isvalid" % (
-                    id_server_scheme, id_server,
-                ),
-            }
-        else:
-            fallback_public_key = public_keys[0]
-
-        if not public_keys:
-            public_keys.append(fallback_public_key)
-        display_name = data["display_name"]
-        defer.returnValue((token, public_keys, fallback_public_key, display_name))
-
-    @defer.inlineCallbacks
-    def forget(self, user, room_id):
-        user_id = user.to_string()
-
-        member = yield 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
-
-        if membership is not None and membership != Membership.LEAVE:
-            raise SynapseError(400, "User %s in room %s" % (
-                user_id, room_id
-            ))
-
-        if membership:
-            yield self.store.forget(user_id, room_id)
-
-
 class RoomListHandler(BaseHandler):
     def __init__(self, hs):
         super(RoomListHandler, self).__init__(hs)
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
new file mode 100644
index 0000000000..5fdbd3adcc
--- /dev/null
+++ b/synapse/handlers/room_member.py
@@ -0,0 +1,646 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# 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.
+
+
+from twisted.internet import defer
+
+from ._base import BaseHandler
+
+from synapse.types import UserID, RoomID, Requester
+from synapse.api.constants import (
+    EventTypes, Membership,
+)
+from synapse.api.errors import AuthError, SynapseError, Codes
+from synapse.util.logcontext import preserve_context_over_fn
+
+from signedjson.sign import verify_signed_json
+from signedjson.key import decode_verify_key_bytes
+
+from unpaddedbase64 import decode_base64
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+id_server_scheme = "https://"
+
+
+def user_left_room(distributor, user, room_id):
+    return preserve_context_over_fn(
+        distributor.fire,
+        "user_left_room", user=user, room_id=room_id
+    )
+
+
+def user_joined_room(distributor, user, room_id):
+    return preserve_context_over_fn(
+        distributor.fire,
+        "user_joined_room", user=user, room_id=room_id
+    )
+
+
+class RoomMemberHandler(BaseHandler):
+    # TODO(paul): This handler currently contains a messy conflation of
+    #   low-level API that works on UserID objects and so on, and REST-level
+    #   API that takes ID strings and returns pagination chunks. These concerns
+    #   ought to be separated out a lot better.
+
+    def __init__(self, hs):
+        super(RoomMemberHandler, self).__init__(hs)
+
+        self.clock = hs.get_clock()
+
+        self.distributor = hs.get_distributor()
+        self.distributor.declare("user_joined_room")
+        self.distributor.declare("user_left_room")
+
+    @defer.inlineCallbacks
+    def get_room_members(self, room_id):
+        users = yield self.store.get_users_in_room(room_id)
+
+        defer.returnValue([UserID.from_string(u) for u in users])
+
+    @defer.inlineCallbacks
+    def fetch_room_distributions_into(self, room_id, localusers=None,
+                                      remotedomains=None, ignore_user=None):
+        """Fetch the distribution of a room, adding elements to either
+        'localusers' or 'remotedomains', which should be a set() if supplied.
+        If ignore_user is set, ignore that user.
+
+        This function returns nothing; its result is performed by the
+        side-effect on the two passed sets. This allows easy accumulation of
+        member lists of multiple rooms at once if required.
+        """
+        members = yield self.get_room_members(room_id)
+        for member in members:
+            if ignore_user is not None and member == ignore_user:
+                continue
+
+            if self.hs.is_mine(member):
+                if localusers is not None:
+                    localusers.add(member)
+            else:
+                if remotedomains is not None:
+                    remotedomains.add(member.domain)
+
+    @defer.inlineCallbacks
+    def update_membership(
+            self,
+            requester,
+            target,
+            room_id,
+            action,
+            txn_id=None,
+            remote_room_hosts=None,
+            third_party_signed=None,
+            ratelimit=True,
+    ):
+        effective_membership_state = action
+        if action in ["kick", "unban"]:
+            effective_membership_state = "leave"
+
+        if third_party_signed is not None:
+            replication = self.hs.get_replication_layer()
+            yield replication.exchange_third_party_invite(
+                third_party_signed["sender"],
+                target.to_string(),
+                room_id,
+                third_party_signed,
+            )
+
+        msg_handler = self.hs.get_handlers().message_handler
+
+        content = {"membership": effective_membership_state}
+        if requester.is_guest:
+            content["kind"] = "guest"
+
+        event, context = yield msg_handler.create_event(
+            {
+                "type": EventTypes.Member,
+                "content": content,
+                "room_id": room_id,
+                "sender": requester.user.to_string(),
+                "state_key": target.to_string(),
+
+                # For backwards compatibility:
+                "membership": effective_membership_state,
+            },
+            token_id=requester.access_token_id,
+            txn_id=txn_id,
+        )
+
+        old_state = context.current_state.get((EventTypes.Member, event.state_key))
+        old_membership = old_state.content.get("membership") if old_state else None
+        if action == "unban" and old_membership != "ban":
+            raise SynapseError(
+                403,
+                "Cannot unban user who was not banned (membership=%s)" % old_membership,
+                errcode=Codes.BAD_STATE
+            )
+        if old_membership == "ban" and action != "unban":
+            raise SynapseError(
+                403,
+                "Cannot %s user who was is banned" % (action,),
+                errcode=Codes.BAD_STATE
+            )
+
+        member_handler = self.hs.get_handlers().room_member_handler
+        yield member_handler.send_membership_event(
+            requester,
+            event,
+            context,
+            ratelimit=ratelimit,
+            remote_room_hosts=remote_room_hosts,
+        )
+
+    @defer.inlineCallbacks
+    def send_membership_event(
+            self,
+            requester,
+            event,
+            context,
+            remote_room_hosts=None,
+            ratelimit=True,
+    ):
+        """
+        Change the membership status of a user in a room.
+
+        Args:
+            requester (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.
+            context: The context of the event.
+            is_guest (bool): Whether the sender is a guest.
+            room_hosts ([str]): Homeservers which are likely to already be in
+                the room, and could be danced with in order to join this
+                homeserver for the first time.
+            ratelimit (bool): Whether to rate limit this request.
+        Raises:
+            SynapseError if there was a problem changing the membership.
+        """
+        remote_room_hosts = remote_room_hosts or []
+
+        target_user = UserID.from_string(event.state_key)
+        room_id = event.room_id
+
+        if requester is not None:
+            sender = UserID.from_string(event.sender)
+            assert sender == requester.user, (
+                "Sender (%s) must be same as requester (%s)" %
+                (sender, requester.user)
+            )
+            assert self.hs.is_mine(sender), "Sender must be our own: %s" % (sender,)
+        else:
+            requester = Requester(target_user, None, False)
+
+        message_handler = self.hs.get_handlers().message_handler
+        prev_event = message_handler.deduplicate_state_event(event, context)
+        if prev_event is not None:
+            return
+
+        action = "send"
+
+        if event.membership == Membership.JOIN:
+            if requester.is_guest and not self._can_guest_join(context.current_state):
+                # 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")
+            do_remote_join_dance, remote_room_hosts = self._should_do_dance(
+                context,
+                (self.get_inviter(event.state_key, context.current_state)),
+                remote_room_hosts,
+            )
+            if do_remote_join_dance:
+                action = "remote_join"
+        elif event.membership == Membership.LEAVE:
+            is_host_in_room = self.is_host_in_room(context.current_state)
+
+            if not is_host_in_room:
+                # perhaps we've been invited
+                inviter = self.get_inviter(
+                    target_user.to_string(), context.current_state
+                )
+                if not inviter:
+                    raise SynapseError(404, "Not a known room")
+
+                if self.hs.is_mine(inviter):
+                    # the inviter was on our server, but has now left. Carry on
+                    # with the normal rejection codepath.
+                    #
+                    # This is a bit of a hack, because the room might still be
+                    # active on other servers.
+                    pass
+                else:
+                    # send the rejection to the inviter's HS.
+                    remote_room_hosts = remote_room_hosts + [inviter.domain]
+                    action = "remote_reject"
+
+        federation_handler = self.hs.get_handlers().federation_handler
+
+        if action == "remote_join":
+            if len(remote_room_hosts) == 0:
+                raise SynapseError(404, "No known servers")
+
+            # We don't do an auth check if we are doing an invite
+            # 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 federation_handler.do_invite_join(
+                remote_room_hosts,
+                event.room_id,
+                event.user_id,
+                event.content,
+            )
+        elif action == "remote_reject":
+            yield federation_handler.do_remotely_reject_invite(
+                remote_room_hosts,
+                room_id,
+                event.user_id
+            )
+        else:
+            yield self.handle_new_client_event(
+                requester,
+                event,
+                context,
+                extra_users=[target_user],
+                ratelimit=ratelimit,
+            )
+
+        prev_member_event = context.current_state.get(
+            (EventTypes.Member, target_user.to_string()),
+            None
+        )
+
+        if event.membership == Membership.JOIN:
+            if not prev_member_event or prev_member_event.membership != Membership.JOIN:
+                # Only fire user_joined_room if the user has acutally joined the
+                # room. Don't bother if the user is just changing their profile
+                # info.
+                yield user_joined_room(self.distributor, target_user, room_id)
+        elif event.membership == Membership.LEAVE:
+            if prev_member_event and prev_member_event.membership == Membership.JOIN:
+                user_left_room(self.distributor, target_user, room_id)
+
+    def _can_guest_join(self, current_state):
+        """
+        Returns whether a guest can join a room based on its current state.
+        """
+        guest_access = current_state.get((EventTypes.GuestAccess, ""), None)
+        return (
+            guest_access
+            and guest_access.content
+            and "guest_access" in guest_access.content
+            and guest_access.content["guest_access"] == "can_join"
+        )
+
+    def _should_do_dance(self, context, inviter, room_hosts=None):
+        # TODO: Shouldn't this be remote_room_host?
+        room_hosts = room_hosts or []
+
+        is_host_in_room = self.is_host_in_room(context.current_state)
+        if is_host_in_room:
+            return False, room_hosts
+
+        if inviter and not self.hs.is_mine(inviter):
+            room_hosts.append(inviter.domain)
+
+        return True, room_hosts
+
+    @defer.inlineCallbacks
+    def lookup_room_alias(self, room_alias):
+        """
+        Get the room ID associated with a room alias.
+
+        Args:
+            room_alias (RoomAlias): The alias to look up.
+        Returns:
+            A tuple of:
+                The room ID as a RoomID object.
+                Hosts likely to be participating in the room ([str]).
+        Raises:
+            SynapseError if room alias could not be found.
+        """
+        directory_handler = self.hs.get_handlers().directory_handler
+        mapping = yield directory_handler.get_association(room_alias)
+
+        if not mapping:
+            raise SynapseError(404, "No such room alias")
+
+        room_id = mapping["room_id"]
+        servers = mapping["servers"]
+
+        defer.returnValue((RoomID.from_string(room_id), servers))
+
+    def get_inviter(self, user_id, current_state):
+        prev_state = current_state.get((EventTypes.Member, user_id))
+        if prev_state and prev_state.membership == Membership.INVITE:
+            return UserID.from_string(prev_state.user_id)
+        return None
+
+    @defer.inlineCallbacks
+    def get_joined_rooms_for_user(self, user):
+        """Returns a list of roomids that the user has any of the given
+        membership states in."""
+
+        rooms = yield self.store.get_rooms_for_user(
+            user.to_string(),
+        )
+
+        # For some reason the list of events contains duplicates
+        # TODO(paul): work out why because I really don't think it should
+        room_ids = set(r.room_id for r in rooms)
+
+        defer.returnValue(room_ids)
+
+    @defer.inlineCallbacks
+    def do_3pid_invite(
+            self,
+            room_id,
+            inviter,
+            medium,
+            address,
+            id_server,
+            requester,
+            txn_id
+    ):
+        invitee = yield self._lookup_3pid(
+            id_server, medium, address
+        )
+
+        if invitee:
+            handler = self.hs.get_handlers().room_member_handler
+            yield handler.update_membership(
+                requester,
+                UserID.from_string(invitee),
+                room_id,
+                "invite",
+                txn_id=txn_id,
+            )
+        else:
+            yield self._make_and_store_3pid_invite(
+                requester,
+                id_server,
+                medium,
+                address,
+                room_id,
+                inviter,
+                txn_id=txn_id
+            )
+
+    @defer.inlineCallbacks
+    def _lookup_3pid(self, id_server, medium, address):
+        """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").
+
+        Returns:
+            (str) the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        try:
+            data = yield self.hs.get_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")
+                self.verify_any_signature(data, id_server)
+                defer.returnValue(data["mxid"])
+
+        except IOError as e:
+            logger.warn("Error from identity server lookup: %s" % (e,))
+            defer.returnValue(None)
+
+    @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.hs.get_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(
+            self,
+            requester,
+            id_server,
+            medium,
+            address,
+            room_id,
+            user,
+            txn_id
+    ):
+        room_state = yield self.hs.get_state_handler().get_current_state(room_id)
+
+        inviter_display_name = ""
+        inviter_avatar_url = ""
+        member_event = room_state.get((EventTypes.Member, user.to_string()))
+        if member_event:
+            inviter_display_name = member_event.content.get("displayname", "")
+            inviter_avatar_url = member_event.content.get("avatar_url", "")
+
+        canonical_room_alias = ""
+        canonical_alias_event = room_state.get((EventTypes.CanonicalAlias, ""))
+        if canonical_alias_event:
+            canonical_room_alias = canonical_alias_event.content.get("alias", "")
+
+        room_name = ""
+        room_name_event = room_state.get((EventTypes.Name, ""))
+        if room_name_event:
+            room_name = room_name_event.content.get("name", "")
+
+        room_join_rules = ""
+        join_rules_event = room_state.get((EventTypes.JoinRules, ""))
+        if join_rules_event:
+            room_join_rules = join_rules_event.content.get("join_rule", "")
+
+        room_avatar_url = ""
+        room_avatar_event = room_state.get((EventTypes.RoomAvatar, ""))
+        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(
+                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
+            )
+        )
+
+        msg_handler = self.hs.get_handlers().message_handler
+        yield msg_handler.create_and_send_nonmember_event(
+            requester,
+            {
+                "type": EventTypes.ThirdPartyInvite,
+                "content": {
+                    "display_name": display_name,
+                    "public_keys": public_keys,
+
+                    # For backwards compatibility:
+                    "key_validity_url": fallback_public_key["key_validity_url"],
+                    "public_key": fallback_public_key["public_key"],
+                },
+                "room_id": room_id,
+                "sender": user.to_string(),
+                "state_key": token,
+            },
+            txn_id=txn_id,
+        )
+
+    @defer.inlineCallbacks
+    def _ask_id_server_for_third_party_invite(
+            self,
+            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
+    ):
+        """
+        Asks an identity server for a third party invite.
+
+        :param id_server (str): hostname + optional port for the identity server.
+        :param medium (str): The literal string "email".
+        :param address (str): The third party address being invited.
+        :param room_id (str): The ID of the room to which the user is invited.
+        :param inviter_user_id (str): The user ID of the inviter.
+        :param room_alias (str): An alias for the room, for cosmetic
+            notifications.
+        :param room_avatar_url (str): The URL of the room's avatar, for cosmetic
+            notifications.
+        :param room_join_rules (str): The join rules of the email
+            (e.g. "public").
+        :param room_name (str): The m.room.name of the room.
+        :param inviter_display_name (str): The current display name of the
+            inviter.
+        :param inviter_avatar_url (str): The URL of the inviter's avatar.
+
+        :return: 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.
+        """
+
+        is_url = "%s%s/_matrix/identity/api/v1/store-invite" % (
+            id_server_scheme, id_server,
+        )
+
+        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,
+        }
+
+        if self.hs.config.invite_3pid_guest:
+            registration_handler = self.hs.get_handlers().registration_handler
+            guest_access_token = yield registration_handler.guest_access_token_for(
+                medium=medium,
+                address=address,
+                inviter_user_id=inviter_user_id,
+            )
+
+            guest_user_info = yield self.hs.get_auth().get_user_by_access_token(
+                guest_access_token
+            )
+
+            invite_config.update({
+                "guest_access_token": guest_access_token,
+                "guest_user_id": guest_user_info["user"].to_string(),
+            })
+
+        data = yield self.hs.get_simple_http_client().post_urlencoded_get_json(
+            is_url,
+            invite_config
+        )
+        # 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": "%s%s/_matrix/identity/api/v1/pubkey/isvalid" % (
+                    id_server_scheme, id_server,
+                ),
+            }
+        else:
+            fallback_public_key = public_keys[0]
+
+        if not public_keys:
+            public_keys.append(fallback_public_key)
+        display_name = data["display_name"]
+        defer.returnValue((token, public_keys, fallback_public_key, display_name))
+
+    @defer.inlineCallbacks
+    def forget(self, user, room_id):
+        user_id = user.to_string()
+
+        member = yield 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
+
+        if membership is not None and membership != Membership.LEAVE:
+            raise SynapseError(400, "User %s in room %s" % (
+                user_id, room_id
+            ))
+
+        if membership:
+            yield self.store.forget(user_id, room_id)