summary refs log tree commit diff
path: root/synapse
diff options
context:
space:
mode:
Diffstat (limited to 'synapse')
-rw-r--r--synapse/api/auth.py4
-rw-r--r--synapse/api/constants.py5
-rw-r--r--synapse/api/errors.py3
-rw-r--r--synapse/app/generic_worker.py5
-rw-r--r--synapse/app/homeserver.py6
-rw-r--r--synapse/config/cache.py20
-rw-r--r--synapse/config/homeserver.py2
-rw-r--r--synapse/config/room.py80
-rw-r--r--synapse/config/saml2_config.py4
-rw-r--r--synapse/config/server.py2
-rw-r--r--synapse/events/__init__.py4
-rw-r--r--synapse/events/snapshot.py4
-rw-r--r--synapse/federation/federation_base.py4
-rw-r--r--synapse/federation/federation_server.py7
-rw-r--r--synapse/federation/send_queue.py8
-rw-r--r--synapse/federation/sender/__init__.py4
-rw-r--r--synapse/handlers/appservice.py4
-rw-r--r--synapse/handlers/auth.py2
-rw-r--r--synapse/handlers/device.py15
-rw-r--r--synapse/handlers/e2e_keys.py14
-rw-r--r--synapse/handlers/e2e_room_keys.py7
-rw-r--r--synapse/handlers/federation.py34
-rw-r--r--synapse/handlers/groups_local.py4
-rw-r--r--synapse/handlers/message.py8
-rw-r--r--synapse/handlers/pagination.py4
-rw-r--r--synapse/handlers/presence.py14
-rw-r--r--synapse/handlers/room.py80
-rw-r--r--synapse/handlers/room_list.py4
-rw-r--r--synapse/handlers/sync.py34
-rw-r--r--synapse/handlers/user_directory.py6
-rw-r--r--synapse/metrics/__init__.py6
-rw-r--r--synapse/push/bulk_push_rule_evaluator.py14
-rw-r--r--synapse/push/push_rule_evaluator.py4
-rw-r--r--synapse/replication/tcp/commands.py4
-rw-r--r--synapse/replication/tcp/handler.py30
-rw-r--r--synapse/rest/client/v1/login.py12
-rw-r--r--synapse/rest/client/v1/presence.py4
-rw-r--r--synapse/rest/media/v1/media_repository.py4
-rw-r--r--synapse/server_notices/consent_server_notices.py4
-rw-r--r--synapse/server_notices/resource_limits_server_notices.py4
-rw-r--r--synapse/state/__init__.py22
-rw-r--r--synapse/state/v1.py26
-rw-r--r--synapse/state/v2.py6
-rw-r--r--synapse/static/client/login/index.html26
-rw-r--r--synapse/static/client/login/js/login.js133
-rw-r--r--synapse/static/client/login/style.css34
-rw-r--r--synapse/storage/data_stores/main/client_ips.py6
-rw-r--r--synapse/storage/data_stores/main/devices.py8
-rw-r--r--synapse/storage/data_stores/main/end_to_end_keys.py6
-rw-r--r--synapse/storage/data_stores/main/event_push_actions.py4
-rw-r--r--synapse/storage/data_stores/main/events.py22
-rw-r--r--synapse/storage/data_stores/main/registration.py4
-rw-r--r--synapse/storage/data_stores/main/roommember.py10
-rw-r--r--synapse/storage/data_stores/main/ui_auth.py2
-rw-r--r--synapse/storage/data_stores/state/bg_updates.py6
-rw-r--r--synapse/storage/data_stores/state/store.py17
-rw-r--r--synapse/storage/database.py13
-rw-r--r--synapse/storage/persist_events.py7
-rw-r--r--synapse/storage/state.py38
-rw-r--r--synapse/util/caches/descriptors.py4
-rw-r--r--synapse/util/caches/expiringcache.py6
-rw-r--r--synapse/util/caches/treecache.py4
-rw-r--r--synapse/visibility.py21
63 files changed, 526 insertions, 377 deletions
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 06ade25674..06ba6604f3 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -16,8 +16,6 @@
 import logging
 from typing import Optional
 
-from six import itervalues
-
 import pymacaroons
 from netaddr import IPAddress
 
@@ -90,7 +88,7 @@ class Auth(object):
             event, prev_state_ids, for_verification=True
         )
         auth_events = yield self.store.get_events(auth_events_ids)
-        auth_events = {(e.type, e.state_key): e for e in itervalues(auth_events)}
+        auth_events = {(e.type, e.state_key): e for e in auth_events.values()}
 
         room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
         event_auth.check(
diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 5ec4a77ccd..6a6d32c302 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -150,3 +150,8 @@ class EventContentFields(object):
     # Timestamp to delete the event after
     # cf https://github.com/matrix-org/matrix-doc/pull/2228
     SELF_DESTRUCT_AFTER = "org.matrix.self_destruct_after"
+
+
+class RoomEncryptionAlgorithms(object):
+    MEGOLM_V1_AES_SHA2 = "m.megolm.v1.aes-sha2"
+    DEFAULT = MEGOLM_V1_AES_SHA2
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index d54dfb385d..a07a54580d 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -19,7 +19,6 @@
 import logging
 from typing import Dict, List
 
-from six import iteritems
 from six.moves import http_client
 
 from canonicaljson import json
@@ -497,7 +496,7 @@ def cs_error(msg, code=Codes.UNKNOWN, **kwargs):
         A dict representing the error response JSON.
     """
     err = {"error": msg, "errcode": code}
-    for key, value in iteritems(kwargs):
+    for key, value in kwargs.items():
         err[key] = value
     return err
 
diff --git a/synapse/app/generic_worker.py b/synapse/app/generic_worker.py
index f3ec2a34ec..53c488d211 100644
--- a/synapse/app/generic_worker.py
+++ b/synapse/app/generic_worker.py
@@ -738,6 +738,11 @@ class GenericWorkerReplicationHandler(ReplicationDataHandler):
         except Exception:
             logger.exception("Error processing replication")
 
+    async def on_position(self, stream_name: str, instance_name: str, token: int):
+        await super().on_position(stream_name, instance_name, token)
+        # Also call on_rdata to ensure that stream positions are properly reset.
+        await self.on_rdata(stream_name, instance_name, token, [])
+
     def stop_pusher(self, user_id, app_id, pushkey):
         if not self.notify_pushers:
             return
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 8454d74858..93bc45208e 100644
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -24,8 +24,6 @@ import os
 import resource
 import sys
 
-from six import iteritems
-
 from prometheus_client import Gauge
 
 from twisted.application import service
@@ -525,7 +523,7 @@ def phone_stats_home(hs, stats, stats_process=_stats_process):
     stats["total_nonbridged_users"] = total_nonbridged_users
 
     daily_user_type_results = yield hs.get_datastore().count_daily_user_type()
-    for name, count in iteritems(daily_user_type_results):
+    for name, count in daily_user_type_results.items():
         stats["daily_user_type_" + name] = count
 
     room_count = yield hs.get_datastore().get_room_count()
@@ -537,7 +535,7 @@ def phone_stats_home(hs, stats, stats_process=_stats_process):
     stats["daily_messages"] = yield hs.get_datastore().count_daily_messages()
 
     r30_results = yield hs.get_datastore().count_r30_users()
-    for name, count in iteritems(r30_results):
+    for name, count in r30_results.items():
         stats["r30_users_" + name] = count
 
     daily_sent_messages = yield hs.get_datastore().count_daily_sent_messages()
diff --git a/synapse/config/cache.py b/synapse/config/cache.py
index 0672538796..aff5b21ab2 100644
--- a/synapse/config/cache.py
+++ b/synapse/config/cache.py
@@ -15,6 +15,7 @@
 
 import os
 import re
+import threading
 from typing import Callable, Dict
 
 from ._base import Config, ConfigError
@@ -25,6 +26,9 @@ _CACHE_PREFIX = "SYNAPSE_CACHE_FACTOR"
 # Map from canonicalised cache name to cache.
 _CACHES = {}
 
+# a lock on the contents of _CACHES
+_CACHES_LOCK = threading.Lock()
+
 _DEFAULT_FACTOR_SIZE = 0.5
 _DEFAULT_EVENT_CACHE_SIZE = "10K"
 
@@ -66,7 +70,10 @@ def add_resizable_cache(cache_name: str, cache_resize_callback: Callable):
     # Some caches have '*' in them which we strip out.
     cache_name = _canonicalise_cache_name(cache_name)
 
-    _CACHES[cache_name] = cache_resize_callback
+    # sometimes caches are initialised from background threads, so we need to make
+    # sure we don't conflict with another thread running a resize operation
+    with _CACHES_LOCK:
+        _CACHES[cache_name] = cache_resize_callback
 
     # Ensure all loaded caches are sized appropriately
     #
@@ -87,7 +94,8 @@ class CacheConfig(Config):
             os.environ.get(_CACHE_PREFIX, _DEFAULT_FACTOR_SIZE)
         )
         properties.resize_all_caches_func = None
-        _CACHES.clear()
+        with _CACHES_LOCK:
+            _CACHES.clear()
 
     def generate_config_section(self, **kwargs):
         return """\
@@ -193,6 +201,8 @@ class CacheConfig(Config):
         For each cache, run the mapped callback function with either
         a specific cache factor or the default, global one.
         """
-        for cache_name, callback in _CACHES.items():
-            new_factor = self.cache_factors.get(cache_name, self.global_factor)
-            callback(new_factor)
+        # block other threads from modifying _CACHES while we iterate it.
+        with _CACHES_LOCK:
+            for cache_name, callback in _CACHES.items():
+                new_factor = self.cache_factors.get(cache_name, self.global_factor)
+                callback(new_factor)
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 2c7b3a699f..264c274c52 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -36,6 +36,7 @@ from .ratelimiting import RatelimitConfig
 from .redis import RedisConfig
 from .registration import RegistrationConfig
 from .repository import ContentRepositoryConfig
+from .room import RoomConfig
 from .room_directory import RoomDirectoryConfig
 from .saml2_config import SAML2Config
 from .server import ServerConfig
@@ -79,6 +80,7 @@ class HomeServerConfig(RootConfig):
         PasswordAuthProviderConfig,
         PushConfig,
         SpamCheckerConfig,
+        RoomConfig,
         GroupsConfig,
         UserDirectoryConfig,
         ConsentConfig,
diff --git a/synapse/config/room.py b/synapse/config/room.py
new file mode 100644
index 0000000000..6aa4de0672
--- /dev/null
+++ b/synapse/config/room.py
@@ -0,0 +1,80 @@
+# -*- 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
+
+from synapse.api.constants import RoomCreationPreset
+
+from ._base import Config, ConfigError
+
+logger = logging.Logger(__name__)
+
+
+class RoomDefaultEncryptionTypes(object):
+    """Possible values for the encryption_enabled_by_default_for_room_type config option"""
+
+    ALL = "all"
+    INVITE = "invite"
+    OFF = "off"
+
+
+class RoomConfig(Config):
+    section = "room"
+
+    def read_config(self, config, **kwargs):
+        # Whether new, locally-created rooms should have encryption enabled
+        encryption_for_room_type = config.get(
+            "encryption_enabled_by_default_for_room_type",
+            RoomDefaultEncryptionTypes.OFF,
+        )
+        if encryption_for_room_type == RoomDefaultEncryptionTypes.ALL:
+            self.encryption_enabled_by_default_for_room_presets = [
+                RoomCreationPreset.PRIVATE_CHAT,
+                RoomCreationPreset.TRUSTED_PRIVATE_CHAT,
+                RoomCreationPreset.PUBLIC_CHAT,
+            ]
+        elif encryption_for_room_type == RoomDefaultEncryptionTypes.INVITE:
+            self.encryption_enabled_by_default_for_room_presets = [
+                RoomCreationPreset.PRIVATE_CHAT,
+                RoomCreationPreset.TRUSTED_PRIVATE_CHAT,
+            ]
+        elif encryption_for_room_type == RoomDefaultEncryptionTypes.OFF:
+            self.encryption_enabled_by_default_for_room_presets = []
+        else:
+            raise ConfigError(
+                "Invalid value for encryption_enabled_by_default_for_room_type"
+            )
+
+    def generate_config_section(self, **kwargs):
+        return """\
+        ## Rooms ##
+
+        # Controls whether locally-created rooms should be end-to-end encrypted by
+        # default.
+        #
+        # Possible options are "all", "invite", and "off". They are defined as:
+        #
+        # * "all": any locally-created room
+        # * "invite": any room created with the "private_chat" or "trusted_private_chat"
+        #             room creation presets
+        # * "off": this option will take no effect
+        #
+        # The default value is "off".
+        #
+        # Note that this option will only affect rooms created after it is set. It
+        # will also not affect rooms created by other servers.
+        #
+        #encryption_enabled_by_default_for_room_type: invite
+        """
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index d0a19751e8..293643b2de 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -160,7 +160,7 @@ class SAML2Config(Config):
 
         # session lifetime: in milliseconds
         self.saml2_session_lifetime = self.parse_duration(
-            saml2_config.get("saml_session_lifetime", "5m")
+            saml2_config.get("saml_session_lifetime", "15m")
         )
 
         template_dir = saml2_config.get("template_dir")
@@ -286,7 +286,7 @@ class SAML2Config(Config):
 
           # The lifetime of a SAML session. This defines how long a user has to
           # complete the authentication process, if allow_unsolicited is unset.
-          # The default is 5 minutes.
+          # The default is 15 minutes.
           #
           #saml_session_lifetime: 5m
 
diff --git a/synapse/config/server.py b/synapse/config/server.py
index f57eefc99c..73226e63d5 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -856,7 +856,7 @@ class ServerConfig(Config):
         # number of monthly active users.
         #
         # 'limit_usage_by_mau' disables/enables monthly active user blocking. When
-        # anabled and a limit is reached the server returns a 'ResourceLimitError'
+        # enabled and a limit is reached the server returns a 'ResourceLimitError'
         # with error type Codes.RESOURCE_LIMIT_EXCEEDED
         #
         # 'max_mau_value' is the hard limit of monthly active users above which
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 533ba327f5..cc5deca75b 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -20,8 +20,6 @@ import os
 from distutils.util import strtobool
 from typing import Dict, Optional, Type
 
-import six
-
 from unpaddedbase64 import encode_base64
 
 from synapse.api.room_versions import EventFormatVersions, RoomVersion, RoomVersions
@@ -290,7 +288,7 @@ class EventBase(metaclass=abc.ABCMeta):
         return list(self._dict.items())
 
     def keys(self):
-        return six.iterkeys(self._dict)
+        return self._dict.keys()
 
     def prev_event_ids(self):
         """Returns the list of prev event IDs. The order matches the order
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 7c5f620d09..f94cdcbaba 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -14,8 +14,6 @@
 # limitations under the License.
 from typing import Optional, Union
 
-from six import iteritems
-
 import attr
 from frozendict import frozendict
 
@@ -341,7 +339,7 @@ def _encode_state_dict(state_dict):
     if state_dict is None:
         return None
 
-    return [(etype, state_key, v) for (etype, state_key), v in iteritems(state_dict)]
+    return [(etype, state_key, v) for (etype, state_key), v in state_dict.items()]
 
 
 def _decode_state_dict(input):
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index c0012c6872..b2ab5bd6a4 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -93,8 +93,8 @@ class FederationBase(object):
                     # *actual* redacted copy to be on the safe side.)
                     redacted_event = prune_event(pdu)
                     if set(redacted_event.keys()) == set(pdu.keys()) and set(
-                        six.iterkeys(redacted_event.content)
-                    ) == set(six.iterkeys(pdu.content)):
+                        redacted_event.content.keys()
+                    ) == set(pdu.content.keys()):
                         logger.info(
                             "Event %s seems to have been redacted; using our redacted "
                             "copy",
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 32a8a2ee46..6920c23723 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -18,7 +18,6 @@ import logging
 from typing import Any, Callable, Dict, List, Match, Optional, Tuple, Union
 
 import six
-from six import iteritems
 
 from canonicaljson import json
 from prometheus_client import Counter
@@ -534,9 +533,9 @@ class FederationServer(FederationBase):
             ",".join(
                 (
                     "%s for %s:%s" % (key_id, user_id, device_id)
-                    for user_id, user_keys in iteritems(json_result)
-                    for device_id, device_keys in iteritems(user_keys)
-                    for key_id, _ in iteritems(device_keys)
+                    for user_id, user_keys in json_result.items()
+                    for device_id, device_keys in user_keys.items()
+                    for key_id, _ in device_keys.items()
                 )
             ),
         )
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index 52f4f54215..6bbd762681 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -33,8 +33,6 @@ import logging
 from collections import namedtuple
 from typing import Dict, List, Tuple, Type
 
-from six import iteritems
-
 from sortedcontainers import SortedDict
 
 from twisted.internet import defer
@@ -327,7 +325,7 @@ class FederationRemoteSendQueue(object):
         # stream position.
         keyed_edus = {v: k for k, v in self.keyed_edu_changed.items()[i:j]}
 
-        for ((destination, edu_key), pos) in iteritems(keyed_edus):
+        for ((destination, edu_key), pos) in keyed_edus.items():
             rows.append(
                 (
                     pos,
@@ -530,10 +528,10 @@ def process_rows_for_federation(transaction_queue, rows):
             states=[state], destinations=destinations
         )
 
-    for destination, edu_map in iteritems(buff.keyed_edus):
+    for destination, edu_map in buff.keyed_edus.items():
         for key, edu in edu_map.items():
             transaction_queue.send_edu(edu, key)
 
-    for destination, edu_list in iteritems(buff.edus):
+    for destination, edu_list in buff.edus.items():
         for edu in edu_list:
             transaction_queue.send_edu(edu, None)
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index d473576902..5b8faea4e7 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -16,8 +16,6 @@
 import logging
 from typing import Dict, Hashable, Iterable, List, Optional, Set, Tuple
 
-from six import itervalues
-
 from prometheus_client import Counter
 
 from twisted.internet import defer
@@ -218,7 +216,7 @@ class FederationSender(object):
                     defer.gatherResults(
                         [
                             run_in_background(handle_room_events, evs)
-                            for evs in itervalues(events_by_room)
+                            for evs in events_by_room.values()
                         ],
                         consumeErrors=True,
                     )
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index fe62f78e67..ac1b64caff 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -15,8 +15,6 @@
 
 import logging
 
-from six import itervalues
-
 from prometheus_client import Counter
 
 from twisted.internet import defer
@@ -125,7 +123,7 @@ class ApplicationServicesHandler(object):
                         defer.gatherResults(
                             [
                                 run_in_background(handle_room_events, evs)
-                                for evs in itervalues(events_by_room)
+                                for evs in events_by_room.values()
                             ],
                             consumeErrors=True,
                         )
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 119678e67b..b01124fe42 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -297,7 +297,7 @@ class AuthHandler(BaseHandler):
 
         # Convert the URI and method to strings.
         uri = request.uri.decode("utf-8")
-        method = request.uri.decode("utf-8")
+        method = request.method.decode("utf-8")
 
         # If there's no session ID, create a new session.
         if not sid:
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 230d170258..31346b56c3 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -17,8 +17,6 @@
 import logging
 from typing import Any, Dict, Optional
 
-from six import iteritems, itervalues
-
 from twisted.internet import defer
 
 from synapse.api import errors
@@ -159,7 +157,7 @@ class DeviceWorkerHandler(BaseHandler):
             # The user may have left the room
             # TODO: Check if they actually did or if we were just invited.
             if room_id not in room_ids:
-                for key, event_id in iteritems(current_state_ids):
+                for key, event_id in current_state_ids.items():
                     etype, state_key = key
                     if etype != EventTypes.Member:
                         continue
@@ -182,7 +180,7 @@ class DeviceWorkerHandler(BaseHandler):
                 log_kv(
                     {"event": "encountered empty previous state", "room_id": room_id}
                 )
-                for key, event_id in iteritems(current_state_ids):
+                for key, event_id in current_state_ids.items():
                     etype, state_key = key
                     if etype != EventTypes.Member:
                         continue
@@ -198,10 +196,10 @@ class DeviceWorkerHandler(BaseHandler):
 
             # Check if we've joined the room? If so we just blindly add all the users to
             # the "possibly changed" users.
-            for state_dict in itervalues(prev_state_ids):
+            for state_dict in prev_state_ids.values():
                 member_event = state_dict.get((EventTypes.Member, user_id), None)
                 if not member_event or member_event != current_member_id:
-                    for key, event_id in iteritems(current_state_ids):
+                    for key, event_id in current_state_ids.items():
                         etype, state_key = key
                         if etype != EventTypes.Member:
                             continue
@@ -211,14 +209,14 @@ class DeviceWorkerHandler(BaseHandler):
             # If there has been any change in membership, include them in the
             # possibly changed list. We'll check if they are joined below,
             # and we're not toooo worried about spuriously adding users.
-            for key, event_id in iteritems(current_state_ids):
+            for key, event_id in current_state_ids.items():
                 etype, state_key = key
                 if etype != EventTypes.Member:
                     continue
 
                 # check if this member has changed since any of the extremities
                 # at the stream_ordering, and add them to the list if so.
-                for state_dict in itervalues(prev_state_ids):
+                for state_dict in prev_state_ids.values():
                     prev_event_id = state_dict.get(key, None)
                     if not prev_event_id or prev_event_id != event_id:
                         if state_key != user_id:
@@ -693,6 +691,7 @@ class DeviceListUpdater(object):
 
         return False
 
+    @trace
     @defer.inlineCallbacks
     def _maybe_retry_device_resync(self):
         """Retry to resync device lists that are out of sync, except if another retry is
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 774a252619..a7e60cbc26 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -17,8 +17,6 @@
 
 import logging
 
-from six import iteritems
-
 import attr
 from canonicaljson import encode_canonical_json, json
 from signedjson.key import decode_verify_key_bytes
@@ -135,7 +133,7 @@ class E2eKeysHandler(object):
         remote_queries_not_in_cache = {}
         if remote_queries:
             query_list = []
-            for user_id, device_ids in iteritems(remote_queries):
+            for user_id, device_ids in remote_queries.items():
                 if device_ids:
                     query_list.extend((user_id, device_id) for device_id in device_ids)
                 else:
@@ -145,9 +143,9 @@ class E2eKeysHandler(object):
                 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):
+            for user_id, devices in remote_results.items():
                 user_devices = results.setdefault(user_id, {})
-                for device_id, device in iteritems(devices):
+                for device_id, device in devices.items():
                     keys = device.get("keys", None)
                     device_display_name = device.get("device_display_name", None)
                     if keys:
@@ -446,9 +444,9 @@ class E2eKeysHandler(object):
             ",".join(
                 (
                     "%s for %s:%s" % (key_id, user_id, device_id)
-                    for user_id, user_keys in iteritems(json_result)
-                    for device_id, device_keys in iteritems(user_keys)
-                    for key_id, _ in iteritems(device_keys)
+                    for user_id, user_keys in json_result.items()
+                    for device_id, device_keys in user_keys.items()
+                    for key_id, _ in device_keys.items()
                 )
             ),
         )
diff --git a/synapse/handlers/e2e_room_keys.py b/synapse/handlers/e2e_room_keys.py
index 9abaf13b8f..f55470a707 100644
--- a/synapse/handlers/e2e_room_keys.py
+++ b/synapse/handlers/e2e_room_keys.py
@@ -16,8 +16,6 @@
 
 import logging
 
-from six import iteritems
-
 from twisted.internet import defer
 
 from synapse.api.errors import (
@@ -205,8 +203,8 @@ class E2eRoomKeysHandler(object):
             )
             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, room_key in iteritems(room["sessions"]):
+            for room_id, room in room_keys["rooms"].items():
+                for session_id, room_key in room["sessions"].items():
                     if not isinstance(room_key["is_verified"], bool):
                         msg = (
                             "is_verified must be a boolean in keys for session %s in"
@@ -351,6 +349,7 @@ class E2eRoomKeysHandler(object):
                     raise
 
             res["count"] = yield self.store.count_e2e_room_keys(user_id, res["version"])
+            res["etag"] = str(res["etag"])
             return res
 
     @trace
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 3e60774b33..d6038d9995 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -21,8 +21,6 @@ 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
@@ -33,7 +31,12 @@ 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.constants import (
+    EventTypes,
+    Membership,
+    RejectedReason,
+    RoomEncryptionAlgorithms,
+)
 from synapse.api.errors import (
     AuthError,
     CodeMessageException,
@@ -393,7 +396,7 @@ class FederationHandler(BaseHandler):
                     )
                     event_map.update(evs)
 
-                    state = [event_map[e] for e in six.itervalues(state_map)]
+                    state = [event_map[e] for e in state_map.values()]
                 except Exception:
                     logger.warning(
                         "[%s %s] Error attempting to resolve state at missing "
@@ -742,7 +745,10 @@ class FederationHandler(BaseHandler):
                 if device:
                     keys = device.get("keys", {}).get("keys", {})
 
-                    if event.content.get("algorithm") == "m.megolm.v1.aes-sha2":
+                    if (
+                        event.content.get("algorithm")
+                        == RoomEncryptionAlgorithms.MEGOLM_V1_AES_SHA2
+                    ):
                         # For this algorithm we expect a curve25519 key.
                         key_name = "curve25519:%s" % (device_id,)
                         current_keys = [keys.get(key_name)]
@@ -1001,7 +1007,7 @@ class FederationHandler(BaseHandler):
             """
             joined_users = [
                 (state_key, int(event.depth))
-                for (e_type, state_key), event in iteritems(state)
+                for (e_type, state_key), event in state.items()
                 if e_type == EventTypes.Member and event.membership == Membership.JOIN
             ]
 
@@ -1091,16 +1097,16 @@ class FederationHandler(BaseHandler):
         states = dict(zip(event_ids, [s.state for s in states]))
 
         state_map = await self.store.get_events(
-            [e_id for ids in itervalues(states) for e_id in itervalues(ids)],
+            [e_id for ids in states.values() for e_id in ids.values()],
             get_prev_content=False,
         )
         states = {
             key: {
                 k: state_map[e_id]
-                for k, e_id in iteritems(state_dict)
+                for k, e_id in state_dict.items()
                 if e_id in state_map
             }
-            for key, state_dict in iteritems(states)
+            for key, state_dict in states.items()
         }
 
         for e_id, _ in sorted_extremeties_tuple:
@@ -1725,7 +1731,7 @@ class FederationHandler(BaseHandler):
         state_groups = await self.state_store.get_state_groups(room_id, [event_id])
 
         if state_groups:
-            _, state = list(iteritems(state_groups)).pop()
+            _, state = list(state_groups.items()).pop()
             results = {(e.type, e.state_key): e for e in state}
 
             if event.is_state():
@@ -2088,7 +2094,7 @@ class FederationHandler(BaseHandler):
                     room_version, state_sets, event
                 )
                 current_state_ids = {
-                    k: e.event_id for k, e in iteritems(current_state_ids)
+                    k: e.event_id for k, e in current_state_ids.items()
                 }
             else:
                 current_state_ids = await self.state_handler.get_current_state_ids(
@@ -2104,7 +2110,7 @@ class FederationHandler(BaseHandler):
             # Now check if event pass auth against said current state
             auth_types = auth_types_for_event(event)
             current_state_ids = [
-                e for k, e in iteritems(current_state_ids) if k in auth_types
+                e for k, e in current_state_ids.items() if k in auth_types
             ]
 
             current_auth_events = await self.store.get_events(current_state_ids)
@@ -2420,7 +2426,7 @@ class FederationHandler(BaseHandler):
         else:
             event_key = None
         state_updates = {
-            k: a.event_id for k, a in iteritems(auth_events) if k != event_key
+            k: a.event_id for k, a in auth_events.items() if k != event_key
         }
 
         current_state_ids = await context.get_current_state_ids()
@@ -2431,7 +2437,7 @@ class FederationHandler(BaseHandler):
         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)})
+        prev_state_ids.update({k: a.event_id for k, a in auth_events.items()})
 
         # create a new state group as a delta from the existing one.
         prev_group = context.state_group
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index ebe8d25bd8..7cb106e365 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -16,8 +16,6 @@
 
 import logging
 
-from six import iteritems
-
 from synapse.api.errors import HttpResponseException, RequestSendFailed, SynapseError
 from synapse.types import get_domain_from_id
 
@@ -227,7 +225,7 @@ class GroupsLocalWorkerHandler(object):
 
         results = {}
         failed_results = []
-        for destination, dest_user_ids in iteritems(destinations):
+        for destination, dest_user_ids in destinations.items():
             try:
                 r = await self.transport_client.bulk_get_publicised_groups(
                     destination, list(dest_user_ids)
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 649ca1f08a..354da9a3b5 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -17,7 +17,7 @@
 import logging
 from typing import Optional, Tuple
 
-from six import iteritems, itervalues, string_types
+from six import string_types
 
 from canonicaljson import encode_canonical_json, json
 
@@ -246,7 +246,7 @@ class MessageHandler(object):
                 "avatar_url": profile.avatar_url,
                 "display_name": profile.display_name,
             }
-            for user_id, profile in iteritems(users_with_profile)
+            for user_id, profile in users_with_profile.items()
         }
 
     def maybe_schedule_expiry(self, event):
@@ -988,7 +988,7 @@ class EventCreationHandler(object):
 
                 state_to_include_ids = [
                     e_id
-                    for k, e_id in iteritems(current_state_ids)
+                    for k, e_id in current_state_ids.items()
                     if k[0] in self.room_invite_state_types
                     or k == (EventTypes.Member, event.sender)
                 ]
@@ -1002,7 +1002,7 @@ class EventCreationHandler(object):
                         "content": e.content,
                         "sender": e.sender,
                     }
-                    for e in itervalues(state_to_include)
+                    for e in state_to_include.values()
                 ]
 
                 invitee = UserID.from_string(event.state_key)
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index d7442c62a7..7fbc229502 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -15,8 +15,6 @@
 # limitations under the License.
 import logging
 
-from six import iteritems
-
 from twisted.internet import defer
 from twisted.python.failure import Failure
 
@@ -145,7 +143,7 @@ class PaginationHandler(object):
 
         logger.debug("[purge] Rooms to purge: %s", rooms)
 
-        for room_id, retention_policy in iteritems(rooms):
+        for room_id, retention_policy in rooms.items():
             logger.info("[purge] Attempting to purge messages in room %s", room_id)
 
             if room_id in self._purges_in_progress_by_room:
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 3594f3b00f..2e8914be14 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -27,8 +27,6 @@ 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
 
@@ -170,14 +168,14 @@ class BasePresenceHandler(abc.ABC):
             for user_id in user_ids
         }
 
-        missing = [user_id for user_id, state in iteritems(states) if not state]
+        missing = [user_id for user_id, state in states.items() 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]
+            missing = [user_id for user_id, state in states.items() if not state]
             if missing:
                 new = {
                     user_id: UserPresenceState.default(user_id) for user_id in missing
@@ -632,7 +630,7 @@ class PresenceHandler(BasePresenceHandler):
             await self._update_states(
                 [
                     prev_state.copy_and_replace(last_user_sync_ts=time_now_ms)
-                    for prev_state in itervalues(prev_states)
+                    for prev_state in prev_states.values()
                 ]
             )
             self.external_process_last_updated_ms.pop(process_id, None)
@@ -1087,7 +1085,7 @@ class PresenceEventSource(object):
             return (list(updates.values()), max_token)
         else:
             return (
-                [s for s in itervalues(updates) if s.state != PresenceState.OFFLINE],
+                [s for s in updates.values() if s.state != PresenceState.OFFLINE],
                 max_token,
             )
 
@@ -1323,11 +1321,11 @@ def get_interested_remotes(store, states, state_handler):
     # hosts in those rooms.
     room_ids_to_states, users_to_states = yield get_interested_parties(store, states)
 
-    for room_id, states in iteritems(room_ids_to_states):
+    for room_id, states in room_ids_to_states.items():
         hosts = yield state_handler.get_current_hosts_in_room(room_id)
         hosts_and_states.append((hosts, states))
 
-    for user_id, states in iteritems(users_to_states):
+    for user_id, states in users_to_states.items():
         host = get_domain_from_id(user_id)
         hosts_and_states.append(([host], states))
 
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 61db3ccc43..f7401373ca 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -24,9 +24,14 @@ import string
 from collections import OrderedDict
 from typing import Tuple
 
-from six import iteritems, string_types
+from six import string_types
 
-from synapse.api.constants import EventTypes, JoinRules, RoomCreationPreset
+from synapse.api.constants import (
+    EventTypes,
+    JoinRules,
+    RoomCreationPreset,
+    RoomEncryptionAlgorithms,
+)
 from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
 from synapse.events.utils import copy_power_levels_contents
@@ -56,31 +61,6 @@ FIVE_MINUTES_IN_MS = 5 * 60 * 1000
 
 
 class RoomCreationHandler(BaseHandler):
-
-    PRESETS_DICT = {
-        RoomCreationPreset.PRIVATE_CHAT: {
-            "join_rules": JoinRules.INVITE,
-            "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": {},
-        },
-    }
-
     def __init__(self, hs):
         super(RoomCreationHandler, self).__init__(hs)
 
@@ -89,6 +69,39 @@ class RoomCreationHandler(BaseHandler):
         self.room_member_handler = hs.get_room_member_handler()
         self.config = hs.config
 
+        # Room state based off defined presets
+        self._presets_dict = {
+            RoomCreationPreset.PRIVATE_CHAT: {
+                "join_rules": JoinRules.INVITE,
+                "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": {},
+            },
+        }
+
+        # Modify presets to selectively enable encryption by default per homeserver config
+        for preset_name, preset_config in self._presets_dict.items():
+            encrypted = (
+                preset_name
+                in self.config.encryption_enabled_by_default_for_room_presets
+            )
+            preset_config["encrypted"] = encrypted
+
         self._replication = hs.get_replication_data_handler()
 
         # linearizer to stop two upgrades happening at once
@@ -364,7 +377,7 @@ class RoomCreationHandler(BaseHandler):
         # map from event_id to BaseEvent
         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):
+        for k, old_event_id in old_room_state_ids.items():
             old_event = old_room_state_events.get(old_event_id)
             if old_event:
                 initial_state[k] = old_event.content
@@ -417,7 +430,7 @@ class RoomCreationHandler(BaseHandler):
         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):
+        for k, old_event in old_room_member_state_events.items():
             # Only transfer ban events
             if (
                 "membership" in old_event.content
@@ -798,7 +811,7 @@ class RoomCreationHandler(BaseHandler):
             )
             return last_stream_id
 
-        config = RoomCreationHandler.PRESETS_DICT[preset_config]
+        config = self._presets_dict[preset_config]
 
         creator_id = creator.user.to_string()
 
@@ -888,6 +901,13 @@ class RoomCreationHandler(BaseHandler):
                 etype=etype, state_key=state_key, content=content
             )
 
+        if config["encrypted"]:
+            last_sent_stream_id = await send(
+                etype=EventTypes.RoomEncryption,
+                state_key="",
+                content={"algorithm": RoomEncryptionAlgorithms.DEFAULT},
+            )
+
         return last_sent_stream_id
 
     async def _generate_room_id(
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index 4cbc02b0d0..5e05be6181 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -17,8 +17,6 @@ import logging
 from collections import namedtuple
 from typing import Any, Dict, Optional
 
-from six import iteritems
-
 import msgpack
 from unpaddedbase64 import decode_base64, encode_base64
 
@@ -271,7 +269,7 @@ class RoomListHandler(BaseHandler):
         event_map = yield self.store.get_events(
             [
                 event_id
-                for key, event_id in iteritems(current_state_ids)
+                for key, event_id in current_state_ids.items()
                 if key[0]
                 in (
                     EventTypes.Create,
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 6bdb24baff..4c7524493e 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -18,8 +18,6 @@ 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
 
@@ -390,7 +388,7 @@ class SyncHandler(object):
                 # result returned by the event source is poor form (it might cache
                 # the object)
                 room_id = event["room_id"]
-                event_copy = {k: v for (k, v) in iteritems(event) if k != "room_id"}
+                event_copy = {k: v for (k, v) in event.items() if k != "room_id"}
                 ephemeral_by_room.setdefault(room_id, []).append(event_copy)
 
             receipt_key = since_token.receipt_key if since_token else "0"
@@ -408,7 +406,7 @@ class SyncHandler(object):
             for event in receipts:
                 room_id = event["room_id"]
                 # exclude room id, as above
-                event_copy = {k: v for (k, v) in iteritems(event) if k != "room_id"}
+                event_copy = {k: v for (k, v) in event.items() if k != "room_id"}
                 ephemeral_by_room.setdefault(room_id, []).append(event_copy)
 
         return now_token, ephemeral_by_room
@@ -454,7 +452,7 @@ class SyncHandler(object):
                     current_state_ids_map = await self.state.get_current_state_ids(
                         room_id
                     )
-                    current_state_ids = frozenset(itervalues(current_state_ids_map))
+                    current_state_ids = frozenset(current_state_ids_map.values())
 
                 recents = await filter_events_for_client(
                     self.storage,
@@ -509,7 +507,7 @@ class SyncHandler(object):
                     current_state_ids_map = await self.state.get_current_state_ids(
                         room_id
                     )
-                    current_state_ids = frozenset(itervalues(current_state_ids_map))
+                    current_state_ids = frozenset(current_state_ids_map.values())
 
                 loaded_recents = await filter_events_for_client(
                     self.storage,
@@ -909,7 +907,7 @@ class SyncHandler(object):
                     logger.debug("filtering state from %r...", state_ids)
                     state_ids = {
                         t: event_id
-                        for t, event_id in iteritems(state_ids)
+                        for t, event_id in state_ids.items()
                         if cache.get(t[1]) != event_id
                     }
                     logger.debug("...to %r", state_ids)
@@ -1430,7 +1428,7 @@ class SyncHandler(object):
         if since_token:
             for joined_sync in sync_result_builder.joined:
                 it = itertools.chain(
-                    joined_sync.timeline.events, itervalues(joined_sync.state)
+                    joined_sync.timeline.events, joined_sync.state.values()
                 )
                 for event in it:
                     if event.type == EventTypes.Member:
@@ -1505,7 +1503,7 @@ class SyncHandler(object):
         newly_left_rooms = []
         room_entries = []
         invited = []
-        for room_id, events in iteritems(mem_change_events_by_room_id):
+        for room_id, events in mem_change_events_by_room_id.items():
             logger.debug(
                 "Membership changes in %s: [%s]",
                 room_id,
@@ -1993,17 +1991,17 @@ def _calculate_state(
     event_id_to_key = {
         e: key
         for key, e in itertools.chain(
-            iteritems(timeline_contains),
-            iteritems(previous),
-            iteritems(timeline_start),
-            iteritems(current),
+            timeline_contains.items(),
+            previous.items(),
+            timeline_start.items(),
+            current.items(),
         )
     }
 
-    c_ids = set(itervalues(current))
-    ts_ids = set(itervalues(timeline_start))
-    p_ids = set(itervalues(previous))
-    tc_ids = set(itervalues(timeline_contains))
+    c_ids = set(current.values())
+    ts_ids = set(timeline_start.values())
+    p_ids = set(previous.values())
+    tc_ids = set(timeline_contains.values())
 
     # 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,
@@ -2017,7 +2015,7 @@ def _calculate_state(
 
     if lazy_load_members:
         p_ids.difference_update(
-            e for t, e in iteritems(timeline_start) if t[0] == EventTypes.Member
+            e for t, e in timeline_start.items() if t[0] == EventTypes.Member
         )
 
     state_ids = ((c_ids | ts_ids) - p_ids) - tc_ids
diff --git a/synapse/handlers/user_directory.py b/synapse/handlers/user_directory.py
index 12423b909a..521b6d620d 100644
--- a/synapse/handlers/user_directory.py
+++ b/synapse/handlers/user_directory.py
@@ -15,8 +15,6 @@
 
 import logging
 
-from six import iteritems, iterkeys
-
 import synapse.metrics
 from synapse.api.constants import EventTypes, JoinRules, Membership
 from synapse.handlers.state_deltas import StateDeltasHandler
@@ -289,7 +287,7 @@ class UserDirectoryHandler(StateDeltasHandler):
         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):
+        for user_id in users_with_profile.keys():
             await self.store.remove_user_who_share_room(user_id, room_id)
 
         # Then, re-add them to the tables.
@@ -298,7 +296,7 @@ class UserDirectoryHandler(StateDeltasHandler):
         # which when ran over an entire room, will result in the same values
         # being added multiple times. The batching upserts shouldn't make this
         # too bad, though.
-        for user_id, profile in iteritems(users_with_profile):
+        for user_id, profile in users_with_profile.items():
             await self._handle_new_user(room_id, user_id, profile)
 
     async def _handle_new_user(self, room_id, user_id, profile):
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index 9cf31f96b3..087a49d65d 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -22,8 +22,6 @@ import threading
 import time
 from typing import Callable, Dict, Iterable, Optional, Tuple, Union
 
-import six
-
 import attr
 from prometheus_client import Counter, Gauge, Histogram
 from prometheus_client.core import (
@@ -83,7 +81,7 @@ class LaterGauge(object):
             return
 
         if isinstance(calls, dict):
-            for k, v in six.iteritems(calls):
+            for k, v in calls.items():
                 g.add_metric(k, v)
         else:
             g.add_metric([], calls)
@@ -194,7 +192,7 @@ class InFlightGauge(object):
             gauge = GaugeMetricFamily(
                 "_".join([self.name, name]), "", labels=self.labels
             )
-            for key, metrics in six.iteritems(metrics_by_key):
+            for key, metrics in metrics_by_key.items():
                 gauge.add_metric(key, getattr(metrics, name))
             yield gauge
 
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index e75d964ac8..43ffe6faf0 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -17,8 +17,6 @@
 import logging
 from collections import namedtuple
 
-from six import iteritems, itervalues
-
 from prometheus_client import Counter
 
 from twisted.internet import defer
@@ -130,7 +128,7 @@ class BulkPushRuleEvaluator(object):
                 event, prev_state_ids, for_verification=False
             )
             auth_events = yield self.store.get_events(auth_events_ids)
-            auth_events = {(e.type, e.state_key): e for e in itervalues(auth_events)}
+            auth_events = {(e.type, e.state_key): e for e in auth_events.values()}
 
         sender_level = get_user_power_level(event.sender, auth_events)
 
@@ -162,7 +160,7 @@ class BulkPushRuleEvaluator(object):
 
         condition_cache = {}
 
-        for uid, rules in iteritems(rules_by_user):
+        for uid, rules in rules_by_user.items():
             if event.sender == uid:
                 continue
 
@@ -395,7 +393,7 @@ class RulesForRoom(object):
         # If the event is a join event then it will be in current state evnts
         # map but not in the DB, so we have to explicitly insert it.
         if event.type == EventTypes.Member:
-            for event_id in itervalues(member_event_ids):
+            for event_id in member_event_ids.values():
                 if event_id == event.event_id:
                     members[event_id] = (event.state_key, event.membership)
 
@@ -404,7 +402,7 @@ class RulesForRoom(object):
 
         interested_in_user_ids = {
             user_id
-            for user_id, membership in itervalues(members)
+            for user_id, membership in members.values()
             if membership == Membership.JOIN
         }
 
@@ -415,7 +413,7 @@ class RulesForRoom(object):
         )
 
         user_ids = {
-            uid for uid, have_pusher in iteritems(if_users_with_pushers) if have_pusher
+            uid for uid, have_pusher in if_users_with_pushers.items() if have_pusher
         }
 
         logger.debug("With pushers: %r", user_ids)
@@ -436,7 +434,7 @@ class RulesForRoom(object):
         )
 
         ret_rules_by_user.update(
-            item for item in iteritems(rules_by_user) if item[0] is not None
+            item for item in rules_by_user.items() if item[0] is not None
         )
 
         self.update_cache(sequence, members, ret_rules_by_user, state_group)
diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py
index 11032491af..aeac257a6e 100644
--- a/synapse/push/push_rule_evaluator.py
+++ b/synapse/push/push_rule_evaluator.py
@@ -131,7 +131,7 @@ class PushRuleEvaluatorForEvent(object):
         # XXX: optimisation: cache our pattern regexps
         if condition["key"] == "content.body":
             body = self._event.content.get("body", None)
-            if not body:
+            if not body or not isinstance(body, str):
                 return False
 
             return _glob_matches(pattern, body, word_boundary=True)
@@ -147,7 +147,7 @@ class PushRuleEvaluatorForEvent(object):
             return False
 
         body = self._event.content.get("body", None)
-        if not body:
+        if not body or not isinstance(body, str):
             return False
 
         # Similar to _glob_matches, but do not treat display_name as a glob.
diff --git a/synapse/replication/tcp/commands.py b/synapse/replication/tcp/commands.py
index c04f622816..ea5937a20c 100644
--- a/synapse/replication/tcp/commands.py
+++ b/synapse/replication/tcp/commands.py
@@ -149,7 +149,7 @@ class RdataCommand(Command):
 
 
 class PositionCommand(Command):
-    """Sent by the server to tell the client the stream postition without
+    """Sent by the server to tell the client the stream position without
     needing to send an RDATA.
 
     Format::
@@ -188,7 +188,7 @@ class ErrorCommand(_SimpleCommand):
 
 
 class PingCommand(_SimpleCommand):
-    """Sent by either side as a keep alive. The data is arbitary (often timestamp)
+    """Sent by either side as a keep alive. The data is arbitrary (often timestamp)
     """
 
     NAME = "PING"
diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py
index cbcf46f3ae..e6a2e2598b 100644
--- a/synapse/replication/tcp/handler.py
+++ b/synapse/replication/tcp/handler.py
@@ -112,8 +112,8 @@ class ReplicationCommandHandler:
             "replication_position", clock=self._clock
         )
 
-        # Map of stream to batched updates. See RdataCommand for info on how
-        # batching works.
+        # Map of stream name to batched updates. See RdataCommand for info on
+        # how batching works.
         self._pending_batches = {}  # type: Dict[str, List[Any]]
 
         # The factory used to create connections.
@@ -123,7 +123,8 @@ class ReplicationCommandHandler:
         # outgoing replication commands to.)
         self._connections = []  # type: List[AbstractConnection]
 
-        # For each connection, the incoming streams that are coming from that connection
+        # For each connection, the incoming stream names that are coming from
+        # that connection.
         self._streams_by_connection = {}  # type: Dict[AbstractConnection, Set[str]]
 
         LaterGauge(
@@ -310,7 +311,28 @@ class ReplicationCommandHandler:
                 # Check if this is the last of a batch of updates
                 rows = self._pending_batches.pop(stream_name, [])
                 rows.append(row)
-                await self.on_rdata(stream_name, cmd.instance_name, cmd.token, rows)
+
+                stream = self._streams.get(stream_name)
+                if not stream:
+                    logger.error("Got RDATA for unknown stream: %s", stream_name)
+                    return
+
+                # Find where we previously streamed up to.
+                current_token = stream.current_token(cmd.instance_name)
+
+                # Discard this data if this token is earlier than the current
+                # position. Note that streams can be reset (in which case you
+                # expect an earlier token), but that must be preceded by a
+                # POSITION command.
+                if cmd.token <= current_token:
+                    logger.debug(
+                        "Discarding RDATA from stream %s at position %s before previous position %s",
+                        stream_name,
+                        cmd.token,
+                        current_token,
+                    )
+                else:
+                    await self.on_rdata(stream_name, cmd.instance_name, cmd.token, rows)
 
     async def on_rdata(
         self, stream_name: str, instance_name: str, token: int, rows: list
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index dceb2792fa..c2c9a9c3aa 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -60,10 +60,18 @@ def login_id_thirdparty_from_phone(identifier):
 
     Returns: Login identifier dict of type 'm.id.threepid'
     """
-    if "country" not in identifier or "number" not in identifier:
+    if "country" not in identifier or (
+        # The specification requires a "phone" field, while Synapse used to require a "number"
+        # field. Accept both for backwards compatibility.
+        "phone" not in identifier
+        and "number" not in identifier
+    ):
         raise SynapseError(400, "Invalid phone-type identifier")
 
-    msisdn = phone_number_to_msisdn(identifier["country"], identifier["number"])
+    # Accept both "phone" and "number" as valid keys in m.id.phone
+    phone_number = identifier.get("phone", identifier["number"])
+
+    msisdn = phone_number_to_msisdn(identifier["country"], phone_number)
 
     return {"type": "m.id.thirdparty", "medium": "msisdn", "address": msisdn}
 
diff --git a/synapse/rest/client/v1/presence.py b/synapse/rest/client/v1/presence.py
index eec16f8ad8..7cf007d35e 100644
--- a/synapse/rest/client/v1/presence.py
+++ b/synapse/rest/client/v1/presence.py
@@ -51,7 +51,9 @@ class PresenceStatusRestServlet(RestServlet):
                 raise AuthError(403, "You are not allowed to see their presence.")
 
         state = await self.presence_handler.get_state(target_user=user)
-        state = format_user_presence_state(state, self.clock.time_msec())
+        state = format_user_presence_state(
+            state, self.clock.time_msec(), include_user_id=False
+        )
 
         return 200, state
 
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index fd10d42f2f..4ee8c60257 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -20,8 +20,6 @@ import os
 import shutil
 from typing import Dict, Tuple
 
-from six import iteritems
-
 import twisted.internet.error
 import twisted.web.http
 from twisted.web.resource import Resource
@@ -606,7 +604,7 @@ class MediaRepository(object):
                 thumbnails[(t_width, t_height, r_type)] = r_method
 
         # Now we generate the thumbnails for each dimension, store it
-        for (t_width, t_height, t_type), t_method in iteritems(thumbnails):
+        for (t_width, t_height, t_type), t_method in thumbnails.items():
             # Generate the thumbnail
             if t_method == "crop":
                 t_byte_source = await defer_to_thread(
diff --git a/synapse/server_notices/consent_server_notices.py b/synapse/server_notices/consent_server_notices.py
index 3bf330da49..e7e8b8e688 100644
--- a/synapse/server_notices/consent_server_notices.py
+++ b/synapse/server_notices/consent_server_notices.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 import logging
 
-from six import iteritems, string_types
+from six import string_types
 
 from synapse.api.errors import SynapseError
 from synapse.api.urls import ConsentURIBuilder
@@ -121,7 +121,7 @@ def copy_with_str_subst(x, substitutions):
     if isinstance(x, string_types):
         return x % substitutions
     if isinstance(x, dict):
-        return {k: copy_with_str_subst(v, substitutions) for (k, v) in iteritems(x)}
+        return {k: copy_with_str_subst(v, substitutions) for (k, v) in x.items()}
     if isinstance(x, (list, tuple)):
         return [copy_with_str_subst(y) for y in x]
 
diff --git a/synapse/server_notices/resource_limits_server_notices.py b/synapse/server_notices/resource_limits_server_notices.py
index 73f2cedb5c..4404ceff93 100644
--- a/synapse/server_notices/resource_limits_server_notices.py
+++ b/synapse/server_notices/resource_limits_server_notices.py
@@ -14,8 +14,6 @@
 # limitations under the License.
 import logging
 
-from six import iteritems
-
 from synapse.api.constants import (
     EventTypes,
     LimitBlockingTypes,
@@ -214,7 +212,7 @@ class ResourceLimitsServerNotices(object):
             referenced_events = list(pinned_state_event.content.get("pinned", []))
 
         events = await self._store.get_events(referenced_events)
-        for event_id, event in iteritems(events):
+        for event_id, event in events.items():
             if event.type != EventTypes.Message:
                 continue
             if event.content.get("msgtype") == ServerNoticeMsgType:
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index 2fa529fcd0..50fd843f66 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -18,8 +18,6 @@ import logging
 from collections import namedtuple
 from typing import Dict, Iterable, List, Optional, Set
 
-from six import iteritems, itervalues
-
 import attr
 from frozendict import frozendict
 from prometheus_client import Histogram
@@ -144,7 +142,7 @@ class StateHandler(object):
             list(state.values()), get_prev_content=False
         )
         state = {
-            key: state_map[e_id] for key, e_id in iteritems(state) if e_id in state_map
+            key: state_map[e_id] for key, e_id in state.items() if e_id in state_map
         }
 
         return state
@@ -423,7 +421,7 @@ class StateHandler(object):
                 state_res_store=StateResolutionStore(self.store),
             )
 
-        new_state = {key: state_map[ev_id] for key, ev_id in iteritems(new_state)}
+        new_state = {key: state_map[ev_id] for key, ev_id in new_state.items()}
 
         return new_state
 
@@ -505,8 +503,8 @@ class StateResolutionHandler(object):
             # resolve_events_with_store do it?
             new_state = {}
             conflicted_state = False
-            for st in itervalues(state_groups_ids):
-                for key, e_id in iteritems(st):
+            for st in state_groups_ids.values():
+                for key, e_id in st.items():
                     if key in new_state:
                         conflicted_state = True
                         break
@@ -520,7 +518,7 @@ class StateResolutionHandler(object):
                     new_state = yield resolve_events_with_store(
                         room_id,
                         room_version,
-                        list(itervalues(state_groups_ids)),
+                        list(state_groups_ids.values()),
                         event_map=event_map,
                         state_res_store=state_res_store,
                     )
@@ -561,12 +559,12 @@ def _make_state_cache_entry(new_state, state_groups_ids):
     # not get persisted.
 
     # first look for exact matches
-    new_state_event_ids = set(itervalues(new_state))
-    for sg, state in iteritems(state_groups_ids):
+    new_state_event_ids = set(new_state.values())
+    for sg, state in state_groups_ids.items():
         if len(new_state_event_ids) != len(state):
             continue
 
-        old_state_event_ids = set(itervalues(state))
+        old_state_event_ids = set(state.values())
         if new_state_event_ids == old_state_event_ids:
             # got an exact match.
             return _StateCacheEntry(state=new_state, state_group=sg)
@@ -579,8 +577,8 @@ def _make_state_cache_entry(new_state, state_groups_ids):
     prev_group = None
     delta_ids = None
 
-    for old_group, old_state in iteritems(state_groups_ids):
-        n_delta_ids = {k: v for k, v in iteritems(new_state) if old_state.get(k) != v}
+    for old_group, old_state in state_groups_ids.items():
+        n_delta_ids = {k: v for k, v in new_state.items() if old_state.get(k) != v}
         if not delta_ids or len(n_delta_ids) < len(delta_ids):
             prev_group = old_group
             delta_ids = n_delta_ids
diff --git a/synapse/state/v1.py b/synapse/state/v1.py
index 9bf98d06f2..7b531a8337 100644
--- a/synapse/state/v1.py
+++ b/synapse/state/v1.py
@@ -17,8 +17,6 @@ import hashlib
 import logging
 from typing import Callable, Dict, List, Optional
 
-from six import iteritems, iterkeys, itervalues
-
 from twisted.internet import defer
 
 from synapse import event_auth
@@ -70,11 +68,11 @@ def resolve_events_with_store(
     unconflicted_state, conflicted_state = _seperate(state_sets)
 
     needed_events = {
-        event_id for event_ids in itervalues(conflicted_state) for event_id in event_ids
+        event_id for event_ids in conflicted_state.values() for event_id in event_ids
     }
     needed_event_count = len(needed_events)
     if event_map is not None:
-        needed_events -= set(iterkeys(event_map))
+        needed_events -= set(event_map.keys())
 
     logger.info(
         "Asking for %d/%d conflicted events", len(needed_events), needed_event_count
@@ -102,11 +100,11 @@ def resolve_events_with_store(
         unconflicted_state, conflicted_state, state_map
     )
 
-    new_needed_events = set(itervalues(auth_events))
+    new_needed_events = set(auth_events.values())
     new_needed_event_count = len(new_needed_events)
     new_needed_events -= needed_events
     if event_map is not None:
-        new_needed_events -= set(iterkeys(event_map))
+        new_needed_events -= set(event_map.keys())
 
     logger.info(
         "Asking for %d/%d auth events", len(new_needed_events), new_needed_event_count
@@ -152,7 +150,7 @@ def _seperate(state_sets):
     conflicted_state = {}
 
     for state_set in state_set_iterator:
-        for key, value in iteritems(state_set):
+        for key, value in state_set.items():
             # Check if there is an unconflicted entry for the state key.
             unconflicted_value = unconflicted_state.get(key)
             if unconflicted_value is None:
@@ -178,7 +176,7 @@ def _seperate(state_sets):
 
 def _create_auth_events_from_maps(unconflicted_state, conflicted_state, state_map):
     auth_events = {}
-    for event_ids in itervalues(conflicted_state):
+    for event_ids in conflicted_state.values():
         for event_id in event_ids:
             if event_id in state_map:
                 keys = event_auth.auth_types_for_event(state_map[event_id])
@@ -194,7 +192,7 @@ def _resolve_with_state(
     unconflicted_state_ids, conflicted_state_ids, auth_event_ids, state_map
 ):
     conflicted_state = {}
-    for key, event_ids in iteritems(conflicted_state_ids):
+    for key, event_ids in conflicted_state_ids.items():
         events = [state_map[ev_id] for ev_id in event_ids if ev_id in state_map]
         if len(events) > 1:
             conflicted_state[key] = events
@@ -203,7 +201,7 @@ def _resolve_with_state(
 
     auth_events = {
         key: state_map[ev_id]
-        for key, ev_id in iteritems(auth_event_ids)
+        for key, ev_id in auth_event_ids.items()
         if ev_id in state_map
     }
 
@@ -214,7 +212,7 @@ def _resolve_with_state(
         raise
 
     new_state = unconflicted_state_ids
-    for key, event in iteritems(resolved_state):
+    for key, event in resolved_state.items():
         new_state[key] = event.event_id
 
     return new_state
@@ -238,21 +236,21 @@ def _resolve_state_events(conflicted_state, auth_events):
 
     auth_events.update(resolved_state)
 
-    for key, events in iteritems(conflicted_state):
+    for key, events in conflicted_state.items():
         if key[0] == EventTypes.JoinRules:
             logger.debug("Resolving conflicted join rules %r", events)
             resolved_state[key] = _resolve_auth_events(events, auth_events)
 
     auth_events.update(resolved_state)
 
-    for key, events in iteritems(conflicted_state):
+    for key, events in conflicted_state.items():
         if key[0] == EventTypes.Member:
             logger.debug("Resolving conflicted member lists %r", events)
             resolved_state[key] = _resolve_auth_events(events, auth_events)
 
     auth_events.update(resolved_state)
 
-    for key, events in iteritems(conflicted_state):
+    for key, events in conflicted_state.items():
         if key not in resolved_state:
             logger.debug("Resolving conflicted state %r:%r", key, events)
             resolved_state[key] = _resolve_normal_events(events, auth_events)
diff --git a/synapse/state/v2.py b/synapse/state/v2.py
index 18484e2fa6..e25bc5d264 100644
--- a/synapse/state/v2.py
+++ b/synapse/state/v2.py
@@ -18,8 +18,6 @@ import itertools
 import logging
 from typing import Dict, List, Optional
 
-from six import iteritems, itervalues
-
 from twisted.internet import defer
 
 import synapse.state
@@ -87,7 +85,7 @@ def resolve_events_with_store(
 
     full_conflicted_set = set(
         itertools.chain(
-            itertools.chain.from_iterable(itervalues(conflicted_state)), auth_diff
+            itertools.chain.from_iterable(conflicted_state.values()), auth_diff
         )
     )
 
@@ -572,7 +570,7 @@ def lexicographical_topological_sort(graph, key):
     # `(key(node), node)` so that sorting does the right thing
     zero_outdegree = []
 
-    for node, edges in iteritems(graph):
+    for node, edges in graph.items():
         if len(edges) == 0:
             zero_outdegree.append((key(node), node))
 
diff --git a/synapse/static/client/login/index.html b/synapse/static/client/login/index.html
index 6fefdaaff7..9e6daf38ac 100644
--- a/synapse/static/client/login/index.html
+++ b/synapse/static/client/login/index.html
@@ -1,24 +1,24 @@
 <!doctype html>
 <html>
 <head>
-<title> Login </title>
-<meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0'>
-<link rel="stylesheet" href="style.css">
-<script src="js/jquery-3.4.1.min.js"></script>
-<script src="js/login.js"></script>
+    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+    <title> Login </title>
+    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0'>
+    <link rel="stylesheet" href="style.css">
+    <script src="js/jquery-3.4.1.min.js"></script>
+    <script src="js/login.js"></script>
 </head>
 <body onload="matrixLogin.onLoad()">
-    <center>
-        <br/>
+    <div id="container">
         <h1 id="title"></h1>
 
-        <span id="feedback" style="color: #f00"></span>
+        <span id="feedback"></span>
 
         <div id="loading">
             <img src="spinner.gif" />
         </div>
 
-        <div id="sso_flow" class="login_flow" style="display:none">
+        <div id="sso_flow" class="login_flow" style="display: none;">
             Single-sign on:
             <form id="sso_form" action="/_matrix/client/r0/login/sso/redirect" method="get">
                 <input id="sso_redirect_url" type="hidden" name="redirectUrl" value=""/>
@@ -26,9 +26,9 @@
             </form>
         </div>
 
-        <div id="password_flow" class="login_flow" style="display:none">
+        <div id="password_flow" class="login_flow" style="display: none;">
             Password Authentication:
-            <form onsubmit="matrixLogin.password_login(); return false;">
+            <form onsubmit="matrixLogin.passwordLogin(); return false;">
                 <input id="user_id" size="32" type="text" placeholder="Matrix ID (e.g. bob)" autocapitalize="off" autocorrect="off" />
                 <br/>
                 <input id="password" size="32" type="password" placeholder="Password"/>
@@ -38,9 +38,9 @@
             </form>
         </div>
 
-        <div id="no_login_types" type="button" class="login_flow" style="display:none">
+        <div id="no_login_types" type="button" class="login_flow" style="display: none;">
             Log in currently unavailable.
         </div>
-    </center>
+    </div>
 </body>
 </html>
diff --git a/synapse/static/client/login/js/login.js b/synapse/static/client/login/js/login.js
index ba8048b23f..3678670ec7 100644
--- a/synapse/static/client/login/js/login.js
+++ b/synapse/static/client/login/js/login.js
@@ -5,11 +5,11 @@ window.matrixLogin = {
 };
 
 // Titles get updated through the process to give users feedback.
-var TITLE_PRE_AUTH = "Log in with one of the following methods";
-var TITLE_POST_AUTH = "Logging in...";
+const TITLE_PRE_AUTH = "Log in with one of the following methods";
+const TITLE_POST_AUTH = "Logging in...";
 
 // The cookie used to store the original query parameters when using SSO.
-var COOKIE_KEY = "synapse_login_fallback_qs";
+const COOKIE_KEY = "synapse_login_fallback_qs";
 
 /*
  * Submit a login request.
@@ -20,9 +20,9 @@ var COOKIE_KEY = "synapse_login_fallback_qs";
  *     login request, e.g. device_id.
  * callback: (Optional) Function to call on successful login.
  */
-var submitLogin = function(type, data, extra, callback) {
+function submitLogin(type, data, extra, callback) {
     console.log("Logging in with " + type);
-    set_title(TITLE_POST_AUTH);
+    setTitle(TITLE_POST_AUTH);
 
     // Add the login type.
     data.type = type;
@@ -41,12 +41,15 @@ var submitLogin = function(type, data, extra, callback) {
         }
         matrixLogin.onLogin(response);
     }).fail(errorFunc);
-};
+}
 
-var errorFunc = function(err) {
+/*
+ * Display an error to the user and show the login form again.
+ */
+function errorFunc(err) {
     // We want to show the error to the user rather than redirecting immediately to the
     // SSO portal (if SSO is the only login option), so we inhibit the redirect.
-    show_login(true);
+    showLogin(true);
 
     if (err.responseJSON && err.responseJSON.error) {
         setFeedbackString(err.responseJSON.error + " (" + err.responseJSON.errcode + ")");
@@ -54,27 +57,42 @@ var errorFunc = function(err) {
     else {
         setFeedbackString("Request failed: " + err.status);
     }
-};
+}
 
-var setFeedbackString = function(text) {
+/*
+ * Display an error to the user.
+ */
+function setFeedbackString(text) {
     $("#feedback").text(text);
-};
+}
 
-var show_login = function(inhibit_redirect) {
-    // Set the redirect to come back to this page, a login token will get added
-    // and handled after the redirect.
-    var this_page = window.location.origin + window.location.pathname;
-    $("#sso_redirect_url").val(this_page);
+/*
+ * (Maybe) Show the login forms.
+ *
+ * This actually does a few unrelated functions:
+ *
+ * * Configures the SSO redirect URL to come back to this page.
+ * * Configures and shows the SSO form, if the server supports SSO.
+ * * Otherwise, shows the password form.
+ */
+function showLogin(inhibitRedirect) {
+    setTitle(TITLE_PRE_AUTH);
 
-    // If inhibit_redirect is false, and SSO is the only supported login method,
+    // If inhibitRedirect is false, and SSO is the only supported login method,
     // we can redirect straight to the SSO page.
     if (matrixLogin.serverAcceptsSso) {
+        // Set the redirect to come back to this page, a login token will get
+        // added as a query parameter and handled after the redirect.
+        $("#sso_redirect_url").val(window.location.origin + window.location.pathname);
+
         // Before submitting SSO, set the current query parameters into a cookie
         // for retrieval later.
         var qs = parseQsFromUrl();
         setCookie(COOKIE_KEY, JSON.stringify(qs));
 
-        if (!inhibit_redirect && !matrixLogin.serverAcceptsPassword) {
+        // If password is not supported and redirects are allowed, then submit
+        // the form (redirecting to the SSO provider).
+        if (!inhibitRedirect && !matrixLogin.serverAcceptsPassword) {
             $("#sso_form").submit();
             return;
         }
@@ -87,30 +105,39 @@ var show_login = function(inhibit_redirect) {
         $("#password_flow").show();
     }
 
+    // If neither password or SSO are supported, show an error to the user.
     if (!matrixLogin.serverAcceptsPassword && !matrixLogin.serverAcceptsSso) {
         $("#no_login_types").show();
     }
 
-    set_title(TITLE_PRE_AUTH);
-
     $("#loading").hide();
-};
+}
 
-var show_spinner = function() {
+/*
+ * Hides the forms and shows a loading throbber.
+ */
+function showSpinner() {
     $("#password_flow").hide();
     $("#sso_flow").hide();
     $("#no_login_types").hide();
     $("#loading").show();
-};
+}
 
-var set_title = function(title) {
+/*
+ * Helper to show the page's main title.
+ */
+function setTitle(title) {
     $("#title").text(title);
-};
+}
 
-var fetch_info = function(cb) {
+/*
+ * Query the login endpoint for the homeserver's supported flows.
+ *
+ * This populates matrixLogin.serverAccepts* variables.
+ */
+function fetchLoginFlows(cb) {
     $.get(matrixLogin.endpoint, function(response) {
-        var serverAcceptsPassword = false;
-        for (var i=0; i<response.flows.length; i++) {
+        for (var i = 0; i < response.flows.length; i++) {
             var flow = response.flows[i];
             if ("m.login.sso" === flow.type) {
                 matrixLogin.serverAcceptsSso = true;
@@ -126,27 +153,41 @@ var fetch_info = function(cb) {
     }).fail(errorFunc);
 }
 
+/*
+ * Called on load to fetch login flows and attempt SSO login (if a token is available).
+ */
 matrixLogin.onLoad = function() {
-    fetch_info(function() {
-        if (!try_token()) {
-            show_login(false);
+    fetchLoginFlows(function() {
+        // (Maybe) attempt logging in via SSO if a token is available.
+        if (!tryTokenLogin()) {
+            showLogin(false);
         }
     });
 };
 
-matrixLogin.password_login = function() {
+/*
+ * Submit simple user & password login.
+ */
+matrixLogin.passwordLogin = function() {
     var user = $("#user_id").val();
     var pwd = $("#password").val();
 
     setFeedbackString("");
 
-    show_spinner();
+    showSpinner();
     submitLogin(
         "m.login.password",
         {user: user, password: pwd},
         parseQsFromUrl());
 };
 
+/*
+ * The onLogin function gets called after a succesful login.
+ *
+ * It is expected that implementations override this to be notified when the
+ * login is complete. The response to the login call is provided as the single
+ * parameter.
+ */
 matrixLogin.onLogin = function(response) {
     // clobber this function
     console.warn("onLogin - This function should be replaced to proceed.");
@@ -155,7 +196,7 @@ matrixLogin.onLogin = function(response) {
 /*
  * Process the query parameters from the current URL into an object.
  */
-var parseQsFromUrl = function() {
+function parseQsFromUrl() {
     var pos = window.location.href.indexOf("?");
     if (pos == -1) {
         return {};
@@ -174,12 +215,12 @@ var parseQsFromUrl = function() {
         result[key] = val;
     });
     return result;
-};
+}
 
 /*
  * Process the cookies and return an object.
  */
-var parseCookies = function() {
+function parseCookies() {
     var allCookies = document.cookie;
     var result = {};
     allCookies.split(";").forEach(function(part) {
@@ -196,32 +237,32 @@ var parseCookies = function() {
         result[key] = val;
     });
     return result;
-};
+}
 
 /*
  * Set a cookie that is valid for 1 hour.
  */
-var setCookie = function(key, value) {
+function setCookie(key, value) {
     // The maximum age is set in seconds.
     var maxAge = 60 * 60;
     // Set the cookie, this defaults to the current domain and path.
     document.cookie = key + "=" + encodeURIComponent(value) + ";max-age=" + maxAge + ";sameSite=lax";
-};
+}
 
 /*
  * Removes a cookie by key.
  */
-var deleteCookie = function(key) {
+function deleteCookie(key) {
     // Delete a cookie by setting the expiration to 0. (Note that the value
     // doesn't matter.)
     document.cookie = key + "=deleted;expires=0";
-};
+}
 
 /*
  * Submits the login token if one is found in the query parameters. Returns a
  * boolean of whether the login token was found or not.
  */
-var try_token = function() {
+function tryTokenLogin() {
     // Check if the login token is in the query parameters.
     var qs = parseQsFromUrl();
 
@@ -233,18 +274,18 @@ var try_token = function() {
     // Retrieve the original query parameters (from before the SSO redirect).
     // They are stored as JSON in a cookie.
     var cookies = parseCookies();
-    var original_query_params = JSON.parse(cookies[COOKIE_KEY] || "{}")
+    var originalQueryParams = JSON.parse(cookies[COOKIE_KEY] || "{}")
 
     // If the login is successful, delete the cookie.
-    var callback = function() {
+    function callback() {
         deleteCookie(COOKIE_KEY);
     }
 
     submitLogin(
         "m.login.token",
         {token: loginToken},
-        original_query_params,
+        originalQueryParams,
         callback);
 
     return true;
-};
+}
diff --git a/synapse/static/client/login/style.css b/synapse/static/client/login/style.css
index 1cce5ed950..83e4f6abc8 100644
--- a/synapse/static/client/login/style.css
+++ b/synapse/static/client/login/style.css
@@ -31,20 +31,44 @@ form {
     margin: 10px 0 0 0;
 }
 
+/*
+ * Add some padding to the viewport.
+ */
+#container {
+    padding: 10px;
+}
+/*
+ * Center all direct children of the main form.
+ */
+#container > * {
+    display: block;
+    margin-left: auto;
+    margin-right: auto;
+    text-align: center;
+}
+
+/*
+ * A wrapper around each login flow.
+ */
 .login_flow {
     width: 300px;
     text-align: left;
     padding: 10px;
     margin-bottom: 40px;
 
-    -webkit-border-radius: 10px;
-    -moz-border-radius: 10px;
     border-radius: 10px;
-
-    -webkit-box-shadow: 0px 0px 20px 0px rgba(0,0,0,0.15);
-    -moz-box-shadow: 0px 0px 20px 0px rgba(0,0,0,0.15);
     box-shadow: 0px 0px 20px 0px rgba(0,0,0,0.15);
 
     background-color: #f8f8f8;
     border: 1px #ccc solid;
 }
+
+/*
+ * Used to show error content.
+ */
+#feedback {
+    /* Red text. */
+    color: #ff0000;
+    /* A little space to not overlap the box-shadow. */
+    margin-bottom: 20px;
+}
diff --git a/synapse/storage/data_stores/main/client_ips.py b/synapse/storage/data_stores/main/client_ips.py
index 71f8d43a76..995d4764a9 100644
--- a/synapse/storage/data_stores/main/client_ips.py
+++ b/synapse/storage/data_stores/main/client_ips.py
@@ -15,8 +15,6 @@
 
 import logging
 
-from six import iteritems
-
 from twisted.internet import defer
 
 from synapse.metrics.background_process_metrics import wrap_as_background_process
@@ -421,7 +419,7 @@ class ClientIpStore(ClientIpBackgroundUpdateStore):
         ):
             self.database_engine.lock_table(txn, "user_ips")
 
-        for entry in iteritems(to_update):
+        for entry in to_update.items():
             (user_id, access_token, ip), (user_agent, device_id, last_seen) = entry
 
             try:
@@ -530,7 +528,7 @@ class ClientIpStore(ClientIpBackgroundUpdateStore):
                 "user_agent": user_agent,
                 "last_seen": last_seen,
             }
-            for (access_token, ip), (user_agent, last_seen) in iteritems(results)
+            for (access_token, ip), (user_agent, last_seen) in results.items()
         ]
 
     @wrap_as_background_process("prune_old_user_ips")
diff --git a/synapse/storage/data_stores/main/devices.py b/synapse/storage/data_stores/main/devices.py
index fb9f798e29..0ff0542453 100644
--- a/synapse/storage/data_stores/main/devices.py
+++ b/synapse/storage/data_stores/main/devices.py
@@ -17,8 +17,6 @@
 import logging
 from typing import List, Optional, Set, Tuple
 
-from six import iteritems
-
 from canonicaljson import json
 
 from twisted.internet import defer
@@ -208,7 +206,7 @@ class DeviceWorkerStore(SQLBaseStore):
         )
 
         # add the updated cross-signing keys to the results list
-        for user_id, result in iteritems(cross_signing_keys_by_user):
+        for user_id, result in cross_signing_keys_by_user.items():
             result["user_id"] = user_id
             # FIXME: switch to m.signing_key_update when MSC1756 is merged into the spec
             results.append(("org.matrix.signing_key_update", result))
@@ -269,7 +267,7 @@ class DeviceWorkerStore(SQLBaseStore):
         )
 
         results = []
-        for user_id, user_devices in iteritems(devices):
+        for user_id, user_devices in devices.items():
             # The prev_id for the first row is always the last row before
             # `from_stream_id`
             prev_id = yield self._get_last_device_update_for_remote_user(
@@ -493,7 +491,7 @@ class DeviceWorkerStore(SQLBaseStore):
         if devices:
             user_devices = devices[user_id]
             results = []
-            for device_id, device in iteritems(user_devices):
+            for device_id, device in user_devices.items():
                 result = {"device_id": device_id}
 
                 key_json = device.get("key_json", None)
diff --git a/synapse/storage/data_stores/main/end_to_end_keys.py b/synapse/storage/data_stores/main/end_to_end_keys.py
index 20698bfd16..1a0842d4b0 100644
--- a/synapse/storage/data_stores/main/end_to_end_keys.py
+++ b/synapse/storage/data_stores/main/end_to_end_keys.py
@@ -16,8 +16,6 @@
 # limitations under the License.
 from typing import Dict, List
 
-from six import iteritems
-
 from canonicaljson import encode_canonical_json, json
 
 from twisted.enterprise.adbapi import Connection
@@ -64,9 +62,9 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
         # Build the result structure, un-jsonify the results, and add the
         # "unsigned" section
         rv = {}
-        for user_id, device_keys in iteritems(results):
+        for user_id, device_keys in results.items():
             rv[user_id] = {}
-            for device_id, device_info in iteritems(device_keys):
+            for device_id, device_info in device_keys.items():
                 r = db_to_json(device_info.pop("key_json"))
                 r["unsigned"] = {}
                 display_name = device_info["device_display_name"]
diff --git a/synapse/storage/data_stores/main/event_push_actions.py b/synapse/storage/data_stores/main/event_push_actions.py
index 0321274de2..bc9f4f08ea 100644
--- a/synapse/storage/data_stores/main/event_push_actions.py
+++ b/synapse/storage/data_stores/main/event_push_actions.py
@@ -16,8 +16,6 @@
 
 import logging
 
-from six import iteritems
-
 from canonicaljson import json
 
 from twisted.internet import defer
@@ -455,7 +453,7 @@ class EventPushActionsWorkerStore(SQLBaseStore):
                 sql,
                 (
                     _gen_entry(user_id, actions)
-                    for user_id, actions in iteritems(user_id_actions)
+                    for user_id, actions in user_id_actions.items()
                 ),
             )
 
diff --git a/synapse/storage/data_stores/main/events.py b/synapse/storage/data_stores/main/events.py
index a6572571b4..8a13101f1d 100644
--- a/synapse/storage/data_stores/main/events.py
+++ b/synapse/storage/data_stores/main/events.py
@@ -21,7 +21,7 @@ from collections import OrderedDict, namedtuple
 from functools import wraps
 from typing import TYPE_CHECKING, Dict, Iterable, List, Tuple
 
-from six import integer_types, iteritems, text_type
+from six import integer_types, text_type
 from six.moves import range
 
 import attr
@@ -232,10 +232,10 @@ class PersistEventsStore:
 
                 event_counter.labels(event.type, origin_type, origin_entity).inc()
 
-            for room_id, new_state in iteritems(current_state_for_room):
+            for room_id, new_state in current_state_for_room.items():
                 self.store.get_current_state_ids.prefill((room_id,), new_state)
 
-            for room_id, latest_event_ids in iteritems(new_forward_extremeties):
+            for room_id, latest_event_ids in new_forward_extremeties.items():
                 self.store.get_latest_event_ids_in_room.prefill(
                     (room_id,), list(latest_event_ids)
                 )
@@ -461,7 +461,7 @@ class PersistEventsStore:
         state_delta_by_room: Dict[str, DeltaState],
         stream_id: int,
     ):
-        for room_id, delta_state in iteritems(state_delta_by_room):
+        for room_id, delta_state in state_delta_by_room.items():
             to_delete = delta_state.to_delete
             to_insert = delta_state.to_insert
 
@@ -545,7 +545,7 @@ class PersistEventsStore:
                     """,
                     [
                         (room_id, key[0], key[1], ev_id, ev_id)
-                        for key, ev_id in iteritems(to_insert)
+                        for key, ev_id in to_insert.items()
                     ],
                 )
 
@@ -642,7 +642,7 @@ class PersistEventsStore:
     def _update_forward_extremities_txn(
         self, txn, new_forward_extremities, max_stream_order
     ):
-        for room_id, new_extrem in iteritems(new_forward_extremities):
+        for room_id, new_extrem in new_forward_extremities.items():
             self.db.simple_delete_txn(
                 txn, table="event_forward_extremities", keyvalues={"room_id": room_id}
             )
@@ -655,7 +655,7 @@ class PersistEventsStore:
             table="event_forward_extremities",
             values=[
                 {"event_id": ev_id, "room_id": room_id}
-                for room_id, new_extrem in iteritems(new_forward_extremities)
+                for room_id, new_extrem in new_forward_extremities.items()
                 for ev_id in new_extrem
             ],
         )
@@ -672,7 +672,7 @@ class PersistEventsStore:
                     "event_id": event_id,
                     "stream_ordering": max_stream_order,
                 }
-                for room_id, new_extrem in iteritems(new_forward_extremities)
+                for room_id, new_extrem in new_forward_extremities.items()
                 for event_id in new_extrem
             ],
         )
@@ -727,7 +727,7 @@ class PersistEventsStore:
                     event.depth, depth_updates.get(event.room_id, event.depth)
                 )
 
-        for room_id, depth in iteritems(depth_updates):
+        for room_id, depth in depth_updates.items():
             self._update_min_depth_for_room_txn(txn, room_id, depth)
 
     def _update_outliers_txn(self, txn, events_and_contexts):
@@ -1497,11 +1497,11 @@ class PersistEventsStore:
             table="event_to_state_groups",
             values=[
                 {"state_group": state_group_id, "event_id": event_id}
-                for event_id, state_group_id in iteritems(state_groups)
+                for event_id, state_group_id in state_groups.items()
             ],
         )
 
-        for event_id, state_group_id in iteritems(state_groups):
+        for event_id, state_group_id in state_groups.items():
             txn.call_after(
                 self.store._get_state_group_for_event.prefill,
                 (event_id,),
diff --git a/synapse/storage/data_stores/main/registration.py b/synapse/storage/data_stores/main/registration.py
index 9768981891..587d4b91c1 100644
--- a/synapse/storage/data_stores/main/registration.py
+++ b/synapse/storage/data_stores/main/registration.py
@@ -19,8 +19,6 @@ import logging
 import re
 from typing import Optional
 
-from six import iterkeys
-
 from twisted.internet import defer
 from twisted.internet.defer import Deferred
 
@@ -753,7 +751,7 @@ class RegistrationWorkerStore(SQLBaseStore):
                 last_send_attempt, validated_at
                 FROM threepid_validation_session WHERE %s
                 """ % (
-                " AND ".join("%s = ?" % k for k in iterkeys(keyvalues)),
+                " AND ".join("%s = ?" % k for k in keyvalues.keys()),
             )
 
             if validated is not None:
diff --git a/synapse/storage/data_stores/main/roommember.py b/synapse/storage/data_stores/main/roommember.py
index 137ebac833..44bab65eac 100644
--- a/synapse/storage/data_stores/main/roommember.py
+++ b/synapse/storage/data_stores/main/roommember.py
@@ -17,8 +17,6 @@
 import logging
 from typing import Iterable, List, Set
 
-from six import iteritems, itervalues
-
 from canonicaljson import json
 
 from twisted.internet import defer
@@ -544,7 +542,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         users_in_room = {}
         member_event_ids = [
             e_id
-            for key, e_id in iteritems(current_state_ids)
+            for key, e_id in current_state_ids.items()
             if key[0] == EventTypes.Member
         ]
 
@@ -561,7 +559,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
                     users_in_room = dict(prev_res)
                     member_event_ids = [
                         e_id
-                        for key, e_id in iteritems(context.delta_ids)
+                        for key, e_id in context.delta_ids.items()
                         if key[0] == EventTypes.Member
                     ]
                     for etype, state_key in context.delta_ids:
@@ -1101,7 +1099,7 @@ class _JoinedHostsCache(object):
             if state_entry.state_group == self.state_group:
                 pass
             elif state_entry.prev_group == self.state_group:
-                for (typ, state_key), event_id in iteritems(state_entry.delta_ids):
+                for (typ, state_key), event_id in state_entry.delta_ids.items():
                     if typ != EventTypes.Member:
                         continue
 
@@ -1131,7 +1129,7 @@ class _JoinedHostsCache(object):
                 self.state_group = state_entry.state_group
             else:
                 self.state_group = object()
-            self._len = sum(len(v) for v in itervalues(self.hosts_to_joined_users))
+            self._len = sum(len(v) for v in self.hosts_to_joined_users.values())
         return frozenset(self.hosts_to_joined_users)
 
     def __len__(self):
diff --git a/synapse/storage/data_stores/main/ui_auth.py b/synapse/storage/data_stores/main/ui_auth.py
index 1d8ee22fb1..ec2f38c373 100644
--- a/synapse/storage/data_stores/main/ui_auth.py
+++ b/synapse/storage/data_stores/main/ui_auth.py
@@ -186,7 +186,7 @@ class UIAuthWorkerStore(SQLBaseStore):
         # The clientdict gets stored as JSON.
         clientdict_json = json.dumps(clientdict)
 
-        self.db.simple_update_one(
+        await self.db.simple_update_one(
             table="ui_auth_sessions",
             keyvalues={"session_id": session_id},
             updatevalues={"clientdict": clientdict_json},
diff --git a/synapse/storage/data_stores/state/bg_updates.py b/synapse/storage/data_stores/state/bg_updates.py
index ff000bc9ec..be1fe97d79 100644
--- a/synapse/storage/data_stores/state/bg_updates.py
+++ b/synapse/storage/data_stores/state/bg_updates.py
@@ -15,8 +15,6 @@
 
 import logging
 
-from six import iteritems
-
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
@@ -280,7 +278,7 @@ class StateBackgroundUpdateStore(StateGroupBackgroundUpdateStore):
 
                         delta_state = {
                             key: value
-                            for key, value in iteritems(curr_state)
+                            for key, value in curr_state.items()
                             if prev_state.get(key, None) != value
                         }
 
@@ -316,7 +314,7 @@ class StateBackgroundUpdateStore(StateGroupBackgroundUpdateStore):
                                     "state_key": key[1],
                                     "event_id": state_id,
                                 }
-                                for key, state_id in iteritems(delta_state)
+                                for key, state_id in delta_state.items()
                             ],
                         )
 
diff --git a/synapse/storage/data_stores/state/store.py b/synapse/storage/data_stores/state/store.py
index f3ad1e4369..b720212e55 100644
--- a/synapse/storage/data_stores/state/store.py
+++ b/synapse/storage/data_stores/state/store.py
@@ -17,7 +17,6 @@ import logging
 from collections import namedtuple
 from typing import Dict, Iterable, List, Set, Tuple
 
-from six import iteritems
 from six.moves import range
 
 from twisted.internet import defer
@@ -263,7 +262,7 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
 
         # And finally update the result dict, by filtering out any extra
         # stuff we pulled out of the database.
-        for group, group_state_dict in iteritems(group_to_state_dict):
+        for group, group_state_dict in group_to_state_dict.items():
             # We just replace any existing entries, as we will have loaded
             # everything we need from the database anyway.
             state[group] = state_filter.filter_state(group_state_dict)
@@ -341,11 +340,11 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
         else:
             non_member_types = non_member_filter.concrete_types()
 
-        for group, group_state_dict in iteritems(group_to_state_dict):
+        for group, group_state_dict in group_to_state_dict.items():
             state_dict_members = {}
             state_dict_non_members = {}
 
-            for k, v in iteritems(group_state_dict):
+            for k, v in group_state_dict.items():
                 if k[0] == EventTypes.Member:
                     state_dict_members[k] = v
                 else:
@@ -432,7 +431,7 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
                             "state_key": key[1],
                             "event_id": state_id,
                         }
-                        for key, state_id in iteritems(delta_ids)
+                        for key, state_id in delta_ids.items()
                     ],
                 )
             else:
@@ -447,7 +446,7 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
                             "state_key": key[1],
                             "event_id": state_id,
                         }
-                        for key, state_id in iteritems(current_state_ids)
+                        for key, state_id in current_state_ids.items()
                     ],
                 )
 
@@ -458,7 +457,7 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
 
             current_member_state_ids = {
                 s: ev
-                for (s, ev) in iteritems(current_state_ids)
+                for (s, ev) in current_state_ids.items()
                 if s[0] == EventTypes.Member
             }
             txn.call_after(
@@ -470,7 +469,7 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
 
             current_non_member_state_ids = {
                 s: ev
-                for (s, ev) in iteritems(current_state_ids)
+                for (s, ev) in current_state_ids.items()
                 if s[0] != EventTypes.Member
             }
             txn.call_after(
@@ -555,7 +554,7 @@ class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore):
                         "state_key": key[1],
                         "event_id": state_id,
                     }
-                    for key, state_id in iteritems(curr_state)
+                    for key, state_id in curr_state.items()
                 ],
             )
 
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index b112ff3df2..645a70934c 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -29,7 +29,6 @@ from typing import (
     TypeVar,
 )
 
-from six import iteritems, iterkeys, itervalues
 from six.moves import intern, range
 
 from prometheus_client import Histogram
@@ -259,7 +258,7 @@ class PerformanceCounters(object):
 
     def interval(self, interval_duration_secs, limit=3):
         counters = []
-        for name, (count, cum_time) in iteritems(self.current_counters):
+        for name, (count, cum_time) in self.current_counters.items():
             prev_count, prev_time = self.previous_counters.get(name, (0, 0))
             counters.append(
                 (
@@ -1053,7 +1052,7 @@ class Database(object):
         sql = ("SELECT %(retcol)s FROM %(table)s") % {"retcol": retcol, "table": table}
 
         if keyvalues:
-            sql += " WHERE %s" % " AND ".join("%s = ?" % k for k in iterkeys(keyvalues))
+            sql += " WHERE %s" % " AND ".join("%s = ?" % k for k in keyvalues.keys())
             txn.execute(sql, list(keyvalues.values()))
         else:
             txn.execute(sql)
@@ -1191,7 +1190,7 @@ class Database(object):
         clause, values = make_in_list_sql_clause(txn.database_engine, column, iterable)
         clauses = [clause]
 
-        for key, value in iteritems(keyvalues):
+        for key, value in keyvalues.items():
             clauses.append("%s = ?" % (key,))
             values.append(value)
 
@@ -1212,7 +1211,7 @@ class Database(object):
     @staticmethod
     def simple_update_txn(txn, table, keyvalues, updatevalues):
         if keyvalues:
-            where = "WHERE %s" % " AND ".join("%s = ?" % k for k in iterkeys(keyvalues))
+            where = "WHERE %s" % " AND ".join("%s = ?" % k for k in keyvalues.keys())
         else:
             where = ""
 
@@ -1351,7 +1350,7 @@ class Database(object):
         clause, values = make_in_list_sql_clause(txn.database_engine, column, iterable)
         clauses = [clause]
 
-        for key, value in iteritems(keyvalues):
+        for key, value in keyvalues.items():
             clauses.append("%s = ?" % (key,))
             values.append(value)
 
@@ -1388,7 +1387,7 @@ class Database(object):
         txn.close()
 
         if cache:
-            min_val = min(itervalues(cache))
+            min_val = min(cache.values())
         else:
             min_val = max_value
 
diff --git a/synapse/storage/persist_events.py b/synapse/storage/persist_events.py
index f159400a87..92dfd709bc 100644
--- a/synapse/storage/persist_events.py
+++ b/synapse/storage/persist_events.py
@@ -20,7 +20,6 @@ import logging
 from collections import deque, namedtuple
 from typing import Iterable, List, Optional, Set, Tuple
 
-from six import iteritems
 from six.moves import range
 
 from prometheus_client import Counter, Histogram
@@ -218,7 +217,7 @@ class EventsPersistenceStorage(object):
             partitioned.setdefault(event.room_id, []).append((event, ctx))
 
         deferreds = []
-        for room_id, evs_ctxs in iteritems(partitioned):
+        for room_id, evs_ctxs in partitioned.items():
             d = self._event_persist_queue.add_to_queue(
                 room_id, evs_ctxs, backfilled=backfilled
             )
@@ -319,7 +318,7 @@ class EventsPersistenceStorage(object):
                             (event, context)
                         )
 
-                    for room_id, ev_ctx_rm in iteritems(events_by_room):
+                    for room_id, ev_ctx_rm in events_by_room.items():
                         latest_event_ids = await self.main_store.get_latest_event_ids_in_room(
                             room_id
                         )
@@ -674,7 +673,7 @@ class EventsPersistenceStorage(object):
 
         to_insert = {
             key: ev_id
-            for key, ev_id in iteritems(current_state)
+            for key, ev_id in current_state.items()
             if ev_id != existing_state.get(key)
         }
 
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index c522c80922..dc568476f4 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -16,8 +16,6 @@
 import logging
 from typing import Iterable, List, TypeVar
 
-from six import iteritems, itervalues
-
 import attr
 
 from twisted.internet import defer
@@ -51,7 +49,7 @@ class StateFilter(object):
         # If `include_others` is set we canonicalise the filter by removing
         # wildcards from the types dictionary
         if self.include_others:
-            self.types = {k: v for k, v in iteritems(self.types) if v is not None}
+            self.types = {k: v for k, v in self.types.items() if v is not None}
 
     @staticmethod
     def all():
@@ -150,7 +148,7 @@ class StateFilter(object):
 
         has_non_member_wildcard = self.include_others or any(
             state_keys is None
-            for t, state_keys in iteritems(self.types)
+            for t, state_keys in self.types.items()
             if t != EventTypes.Member
         )
 
@@ -199,7 +197,7 @@ class StateFilter(object):
 
         # First we build up a lost of clauses for each type/state_key combo
         clauses = []
-        for etype, state_keys in iteritems(self.types):
+        for etype, state_keys in self.types.items():
             if state_keys is None:
                 clauses.append("(type = ?)")
                 where_args.append(etype)
@@ -251,7 +249,7 @@ class StateFilter(object):
             return dict(state_dict)
 
         filtered_state = {}
-        for k, v in iteritems(state_dict):
+        for k, v in state_dict.items():
             typ, state_key = k
             if typ in self.types:
                 state_keys = self.types[typ]
@@ -279,7 +277,7 @@ class StateFilter(object):
         """
 
         return self.include_others or any(
-            state_keys is None for state_keys in itervalues(self.types)
+            state_keys is None for state_keys in self.types.values()
         )
 
     def concrete_types(self):
@@ -292,7 +290,7 @@ class StateFilter(object):
         """
         return [
             (t, s)
-            for t, state_keys in iteritems(self.types)
+            for t, state_keys in self.types.items()
             if state_keys is not None
             for s in state_keys
         ]
@@ -324,7 +322,7 @@ class StateFilter(object):
             member_filter = StateFilter.none()
 
         non_member_filter = StateFilter(
-            types={k: v for k, v in iteritems(self.types) if k != EventTypes.Member},
+            types={k: v for k, v in self.types.items() if k != EventTypes.Member},
             include_others=self.include_others,
         )
 
@@ -366,7 +364,7 @@ class StateGroupStorage(object):
 
         event_to_groups = yield self.stores.main._get_state_group_for_events(event_ids)
 
-        groups = set(itervalues(event_to_groups))
+        groups = set(event_to_groups.values())
         group_to_state = yield self.stores.state._get_state_for_groups(groups)
 
         return group_to_state
@@ -400,8 +398,8 @@ class StateGroupStorage(object):
         state_event_map = yield self.stores.main.get_events(
             [
                 ev_id
-                for group_ids in itervalues(group_to_ids)
-                for ev_id in itervalues(group_ids)
+                for group_ids in group_to_ids.values()
+                for ev_id in group_ids.values()
             ],
             get_prev_content=False,
         )
@@ -409,10 +407,10 @@ class StateGroupStorage(object):
         return {
             group: [
                 state_event_map[v]
-                for v in itervalues(event_id_map)
+                for v in event_id_map.values()
                 if v in state_event_map
             ]
-            for group, event_id_map in iteritems(group_to_ids)
+            for group, event_id_map in group_to_ids.items()
         }
 
     def _get_state_groups_from_groups(
@@ -444,23 +442,23 @@ class StateGroupStorage(object):
         """
         event_to_groups = yield self.stores.main._get_state_group_for_events(event_ids)
 
-        groups = set(itervalues(event_to_groups))
+        groups = set(event_to_groups.values())
         group_to_state = yield self.stores.state._get_state_for_groups(
             groups, state_filter
         )
 
         state_event_map = yield self.stores.main.get_events(
-            [ev_id for sd in itervalues(group_to_state) for ev_id in itervalues(sd)],
+            [ev_id for sd in group_to_state.values() for ev_id in sd.values()],
             get_prev_content=False,
         )
 
         event_to_state = {
             event_id: {
                 k: state_event_map[v]
-                for k, v in iteritems(group_to_state[group])
+                for k, v in group_to_state[group].items()
                 if v in state_event_map
             }
-            for event_id, group in iteritems(event_to_groups)
+            for event_id, group in event_to_groups.items()
         }
 
         return {event: event_to_state[event] for event in event_ids}
@@ -481,14 +479,14 @@ class StateGroupStorage(object):
         """
         event_to_groups = yield self.stores.main._get_state_group_for_events(event_ids)
 
-        groups = set(itervalues(event_to_groups))
+        groups = set(event_to_groups.values())
         group_to_state = yield self.stores.state._get_state_for_groups(
             groups, state_filter
         )
 
         event_to_state = {
             event_id: group_to_state[group]
-            for event_id, group in iteritems(event_to_groups)
+            for event_id, group in event_to_groups.items()
         }
 
         return {event: event_to_state[event] for event in event_ids}
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index cd48262420..64f35fc288 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -21,8 +21,6 @@ import threading
 from typing import Any, Tuple, Union, cast
 from weakref import WeakValueDictionary
 
-from six import itervalues
-
 from prometheus_client import Gauge
 from typing_extensions import Protocol
 
@@ -281,7 +279,7 @@ class Cache(object):
     def invalidate_all(self):
         self.check_thread()
         self.cache.clear()
-        for entry in itervalues(self._pending_deferred_cache):
+        for entry in self._pending_deferred_cache.values():
             entry.invalidate()
         self._pending_deferred_cache.clear()
 
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 2726b67b6d..89a3420f92 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -16,8 +16,6 @@
 import logging
 from collections import OrderedDict
 
-from six import iteritems, itervalues
-
 from synapse.config import cache as cache_config
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.util.caches import register_cache
@@ -150,7 +148,7 @@ class ExpiringCache(object):
 
         keys_to_delete = set()
 
-        for key, cache_entry in iteritems(self._cache):
+        for key, cache_entry in self._cache.items():
             if now - cache_entry.time > self._expiry_ms:
                 keys_to_delete.add(key)
 
@@ -170,7 +168,7 @@ class ExpiringCache(object):
 
     def __len__(self):
         if self.iterable:
-            return sum(len(entry.value) for entry in itervalues(self._cache))
+            return sum(len(entry.value) for entry in self._cache.values())
         else:
             return len(self._cache)
 
diff --git a/synapse/util/caches/treecache.py b/synapse/util/caches/treecache.py
index 2ea4e4e911..ecd9948e79 100644
--- a/synapse/util/caches/treecache.py
+++ b/synapse/util/caches/treecache.py
@@ -1,7 +1,5 @@
 from typing import Dict
 
-from six import itervalues
-
 SENTINEL = object()
 
 
@@ -81,7 +79,7 @@ def iterate_tree_cache_entry(d):
     can contain dicts.
     """
     if isinstance(d, dict):
-        for value_d in itervalues(d):
+        for value_d in d.values():
             for value in iterate_tree_cache_entry(value_d):
                 yield value
     else:
diff --git a/synapse/visibility.py b/synapse/visibility.py
index bab41182b9..780927cda1 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -16,7 +16,6 @@
 import logging
 import operator
 
-from six import iteritems, itervalues
 from six.moves import map
 
 from twisted.internet import defer
@@ -298,7 +297,7 @@ def filter_events_for_server(
                 # membership states for the requesting server to determine
                 # if the server is either in the room or has been invited
                 # into the room.
-                for ev in itervalues(state):
+                for ev in state.values():
                     if ev.type != EventTypes.Member:
                         continue
                     try:
@@ -332,7 +331,7 @@ def filter_events_for_server(
     )
 
     visibility_ids = set()
-    for sids in itervalues(event_to_state_ids):
+    for sids in event_to_state_ids.values():
         hist = sids.get((EventTypes.RoomHistoryVisibility, ""))
         if hist:
             visibility_ids.add(hist)
@@ -345,7 +344,7 @@ def filter_events_for_server(
         event_map = yield storage.main.get_events(visibility_ids)
         all_open = all(
             e.content.get("history_visibility") in (None, "shared", "world_readable")
-            for e in itervalues(event_map)
+            for e in event_map.values()
         )
 
     if not check_history_visibility_only:
@@ -394,8 +393,8 @@ def filter_events_for_server(
     #
     event_id_to_state_key = {
         event_id: key
-        for key_to_eid in itervalues(event_to_state_ids)
-        for key, event_id in iteritems(key_to_eid)
+        for key_to_eid in event_to_state_ids.values()
+        for key, event_id in key_to_eid.items()
     }
 
     def include(typ, state_key):
@@ -409,20 +408,16 @@ def filter_events_for_server(
         return state_key[idx + 1 :] == server_name
 
     event_map = yield storage.main.get_events(
-        [
-            e_id
-            for e_id, key in iteritems(event_id_to_state_key)
-            if include(key[0], key[1])
-        ]
+        [e_id for e_id, key in event_id_to_state_key.items() if include(key[0], key[1])]
     )
 
     event_to_state = {
         e_id: {
             key: event_map[inner_e_id]
-            for key, inner_e_id in iteritems(key_to_eid)
+            for key, inner_e_id in key_to_eid.items()
             if inner_e_id in event_map
         }
-        for e_id, key_to_eid in iteritems(event_to_state_ids)
+        for e_id, key_to_eid in event_to_state_ids.items()
     }
 
     to_return = []