Add knocking support (#81)

Implement knocking as defined by matrix-org/matrix-spec-proposals#2403 This is the base knocking stuff, taken from matrix-org/synapse#6739 and does not include any public room directory changes. While knocking hasn't merged yet on mainline due to waiting on getting Complement into Synapse's CI, the code has been well-tested.
matrix-org · Feb 9, 2021 · 6bf58d8 · 6bf58d8
1 parent 2c896f1
commit 6bf58d8
Show file tree

Hide file tree

Showing 34 changed files with 1,567 additions and 117 deletions.
diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
@@ -511,7 +511,7 @@ steps:
       - "docker build -t complement-synapse -f complement-master/dockerfiles/Synapse.Dockerfile complement-master/dockerfiles"
       # Finally, compile and run the tests.
       - "cd complement-master"
-      - "COMPLEMENT_BASE_IMAGE=complement-synapse:latest go test -v -tags synapse_blacklist ./tests"
+      - "COMPLEMENT_BASE_IMAGE=complement-synapse:latest go test -v -tags synapse_blacklist,msc2403 ./tests"
     label: "\U0001F9EA Complement"
     agents:
       queue: "medium"

diff --git a/changelog.d/6739.feature b/changelog.d/6739.feature
@@ -0,0 +1 @@
+Implement "room knocking" as per [MSC2403](https://github.com/matrix-org/matrix-doc/pull/2403). Contributed by Sorunome and anoa.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
@@ -1565,7 +1565,9 @@ metrics_flags:
 
 ## API Configuration ##
 
-# A list of event types that will be included in the room_invite_state
+# A list of event types from a room that will be given to users when they
+# are invited to a room. This allows clients to display information about the
+# room that they've been invited to, without actually being in the room yet.
 #
 #room_invite_state_types:
 #  - "m.room.join_rules"

diff --git a/synapse/api/constants.py b/synapse/api/constants.py
@@ -34,7 +34,7 @@ class Membership:
 
     INVITE = "invite"
     JOIN = "join"
-    KNOCK = "knock"
+    KNOCK = "xyz.amorgan.knock"
     LEAVE = "leave"
     BAN = "ban"
     LIST = (INVITE, JOIN, KNOCK, LEAVE, BAN)
@@ -50,7 +50,7 @@ class PresenceState:
 
 class JoinRules:
     PUBLIC = "public"
-    KNOCK = "knock"
+    KNOCK = "xyz.amorgan.knock"
     INVITE = "invite"
     PRIVATE = "private"
 

diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
@@ -57,7 +57,7 @@ class RoomVersion:
     state_res = attr.ib()  # int; one of the StateResolutionVersions
     enforce_key_validity = attr.ib()  # bool
 
-    # bool: before MSC2261/MSC2432, m.room.aliases had special auth rules and redaction rules
+    # Before MSC2432, m.room.aliases had special auth rules and redaction rules
     special_case_aliases_auth = attr.ib(type=bool)
     # Strictly enforce canonicaljson, do not allow:
     # * Integers outside the range of [-2 ^ 53 + 1, 2 ^ 53 - 1]
@@ -67,6 +67,11 @@ class RoomVersion:
     # bool: MSC2209: Check 'notifications' key while verifying
     # m.room.power_levels auth rules.
     limit_notifications_power_levels = attr.ib(type=bool)
+    # MSC2174/MSC2176: Apply updated redaction rules algorithm.
+    msc2176_redaction_rules = attr.ib(type=bool)
+    # MSC2403: Allows join_rules to be set to 'knock', changes auth rules to allow sending
+    # m.room.membership event with membership 'knock'.
+    allow_knocking = attr.ib(type=bool)
 
 
 class RoomVersions:
@@ -79,6 +84,8 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
+        msc2176_redaction_rules=False,
+        allow_knocking=False,
     )
     V2 = RoomVersion(
         "2",
@@ -89,6 +96,8 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
+        msc2176_redaction_rules=False,
+        allow_knocking=False,
     )
     V3 = RoomVersion(
         "3",
@@ -99,6 +108,8 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
+        msc2176_redaction_rules=False,
+        allow_knocking=False,
     )
     V4 = RoomVersion(
         "4",
@@ -109,6 +120,8 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
+        msc2176_redaction_rules=False,
+        allow_knocking=False,
     )
     V5 = RoomVersion(
         "5",
@@ -119,6 +132,8 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
+        msc2176_redaction_rules=False,
+        allow_knocking=False,
     )
     V6 = RoomVersion(
         "6",
@@ -129,6 +144,32 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
+        msc2176_redaction_rules=False,
+        allow_knocking=False,
+    )
+    MSC2176 = RoomVersion(
+        "org.matrix.msc2176",
+        RoomDisposition.UNSTABLE,
+        EventFormatVersions.V3,
+        StateResolutionVersions.V2,
+        enforce_key_validity=True,
+        special_case_aliases_auth=False,
+        strict_canonicaljson=True,
+        limit_notifications_power_levels=True,
+        msc2176_redaction_rules=True,
+        allow_knocking=False,
+    )
+    MSC2403_DEV = RoomVersion(
+        "xyz.amorgan.knock",
+        RoomDisposition.UNSTABLE,
+        EventFormatVersions.V3,
+        StateResolutionVersions.V2,
+        enforce_key_validity=True,
+        special_case_aliases_auth=False,
+        strict_canonicaljson=True,
+        limit_notifications_power_levels=True,
+        msc2176_redaction_rules=False,
+        allow_knocking=True,
     )
 
 

diff --git a/synapse/appservice/api.py b/synapse/appservice/api.py
@@ -18,7 +18,7 @@
 
 from prometheus_client import Counter
 
-from synapse.api.constants import EventTypes, ThirdPartyEntityKind
+from synapse.api.constants import EventTypes, Membership, ThirdPartyEntityKind
 from synapse.api.errors import CodeMessageException
 from synapse.events import EventBase
 from synapse.events.utils import serialize_event
@@ -249,9 +249,14 @@ def _serialize(self, service, events):
                 e,
                 time_now,
                 as_client_event=True,
-                is_invite=(
+                # If this is an invite or a knock membership event, and we're interested
+                # in this user, then include any stripped state alongside the event.
+                include_stripped_room_state=(
                     e.type == EventTypes.Member
-                    and e.membership == "invite"
+                    and (
+                        e.membership == Membership.INVITE
+                        or e.membership == Membership.KNOCK
+                    )
                     and service.is_interested_in_user(e.state_key)
                 ),
             )

diff --git a/synapse/config/_base.pyi b/synapse/config/_base.pyi
@@ -9,6 +9,7 @@ from synapse.config import (
     consent_config,
     database,
     emailconfig,
+    experimental,
     groups,
     jwt_config,
     key,
@@ -46,6 +47,7 @@ def path_exists(file_path: str): ...
 
 class RootConfig:
     server: server.ServerConfig
+    experimental: experimental.ExperimentalConfig
     tls: tls.TlsConfig
     database: database.DatabaseConfig
     logging: logger.LoggingConfig

diff --git a/synapse/config/api.py b/synapse/config/api.py
@@ -1,4 +1,5 @@
 # Copyright 2015, 2016 OpenMarket Ltd
+# Copyright 2020 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -16,27 +17,31 @@
 
 from ._base import Config
 
+# The default types of room state to send to users to are invited to or knock on a room.
+DEFAULT_ROOM_STATE_TYPES = [
+    EventTypes.JoinRules,
+    EventTypes.CanonicalAlias,
+    EventTypes.RoomAvatar,
+    EventTypes.RoomEncryption,
+    EventTypes.Name,
+]
+
 
 class ApiConfig(Config):
     section = "api"
 
     def read_config(self, config, **kwargs):
         self.room_invite_state_types = config.get(
-            "room_invite_state_types",
-            [
-                EventTypes.JoinRules,
-                EventTypes.CanonicalAlias,
-                EventTypes.RoomAvatar,
-                EventTypes.RoomEncryption,
-                EventTypes.Name,
-            ],
+            "room_invite_state_types", DEFAULT_ROOM_STATE_TYPES
         )
 
     def generate_config_section(cls, **kwargs):
         return """\
         ## API Configuration ##
 
-        # A list of event types that will be included in the room_invite_state
+        # A list of event types from a room that will be given to users when they
+        # are invited to a room. This allows clients to display information about the
+        # room that they've been invited to, without actually being in the room yet.
         #
         #room_invite_state_types:
         #  - "{JoinRules}"

diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+# Copyright 2021 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.
+
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersions
+from synapse.config._base import Config
+from synapse.types import JsonDict
+
+
+class ExperimentalConfig(Config):
+    """Config section for enabling experimental features"""
+
+    section = "experimental"
+
+    def read_config(self, config: JsonDict, **kwargs):
+        experimental = config.get("experimental_features") or {}
+
+        # MSC2403 (room knocking)
+        self.msc2403_enabled = experimental.get("msc2403_enabled", False)  # type: bool
+        if self.msc2403_enabled:
+            # Enable the MSC2403 unstable room version
+            KNOWN_ROOM_VERSIONS.update(
+                {RoomVersions.MSC2403_DEV.identifier: RoomVersions.MSC2403_DEV}
+            )
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
@@ -23,6 +23,7 @@
 from .consent_config import ConsentConfig
 from .database import DatabaseConfig
 from .emailconfig import EmailConfig
+from .experimental import ExperimentalConfig
 from .federation import FederationConfig
 from .groups import GroupsConfig
 from .jwt_config import JWTConfig
@@ -57,6 +58,7 @@ class HomeServerConfig(RootConfig):
 
     config_classes = [
         ServerConfig,
+        ExperimentalConfig,
         TlsConfig,
         FederationConfig,
         CacheConfig,

diff --git a/synapse/event_auth.py b/synapse/event_auth.py
@@ -161,6 +161,7 @@ def check(
     if logger.isEnabledFor(logging.DEBUG):
         logger.debug("Auth events: %s", [a.event_id for a in auth_events.values()])
 
+    # 5. If type is m.room.membership
     if event.type == EventTypes.Member:
         _is_membership_change_allowed(event, auth_events)
         logger.debug("Allowing! %s", event)
@@ -247,6 +248,7 @@ def _is_membership_change_allowed(
 
     caller_in_room = caller and caller.membership == Membership.JOIN
     caller_invited = caller and caller.membership == Membership.INVITE
+    caller_knocked = caller and caller.membership == Membership.KNOCK
 
     # get info about the target
     key = (EventTypes.Member, target_user_id)
@@ -289,9 +291,12 @@ def _is_membership_change_allowed(
             raise AuthError(403, "%s is banned from the room" % (target_user_id,))
         return
 
-    if Membership.JOIN != membership:
+    # Require the user to be in the room for membership changes other than join/knock.
+    if Membership.JOIN != membership and Membership.KNOCK != membership:
+        # If the user has been invited or has knocked, they are allowed to change their
+        # membership event to leave
         if (
-            caller_invited
+            (caller_invited or caller_knocked)
             and Membership.LEAVE == membership
             and target_user_id == event.user_id
         ):
@@ -324,7 +329,7 @@ def _is_membership_change_allowed(
             raise AuthError(403, "You are banned from this room")
         elif join_rule == JoinRules.PUBLIC:
             pass
-        elif join_rule == JoinRules.INVITE:
+        elif join_rule in (JoinRules.INVITE, JoinRules.KNOCK):
             if not caller_in_room and not caller_invited:
                 raise AuthError(403, "You are not invited to this room.")
         else:
@@ -343,6 +348,19 @@ def _is_membership_change_allowed(
     elif Membership.BAN == membership:
         if user_level < ban_level or user_level <= target_level:
             raise AuthError(403, "You don't have permission to ban")
+    elif Membership.KNOCK == membership:
+        if join_rule != JoinRules.KNOCK:
+            raise AuthError(403, "You don't have permission to knock")
+        elif target_user_id != event.user_id:
+            raise AuthError(403, "You cannot knock for other users")
+        elif target_in_room:
+            raise AuthError(403, "You cannot knock on a room you are already in")
+        elif caller_knocked:
+            raise AuthError(403, "You already have a pending knock for this room")
+        elif caller_invited:
+            raise AuthError(403, "You are already invited to this room")
+        elif target_banned:
+            raise AuthError(403, "You are banned from this room")
     else:
         raise AuthError(500, "Unknown membership %s" % membership)
 
@@ -699,7 +717,7 @@ def auth_types_for_event(event: EventBase) -> Set[Tuple[str, str]]:
 
     if event.type == EventTypes.Member:
         membership = event.content["membership"]
-        if membership in [Membership.JOIN, Membership.INVITE]:
+        if membership in [Membership.JOIN, Membership.INVITE, Membership.KNOCK]:
             auth_types.add((EventTypes.JoinRules, ""))
 
         auth_types.add((EventTypes.Member, event.state_key))

diff --git a/synapse/events/utils.py b/synapse/events/utils.py
@@ -228,6 +228,7 @@ def format_event_for_client_v1(d):
         "replaces_state",
         "prev_content",
         "invite_room_state",
+        "knock_room_state",
     )
     for key in copy_keys:
         if key in d["unsigned"]:
@@ -264,7 +265,7 @@ def serialize_event(
     event_format=format_event_for_client_v1,
     token_id=None,
     only_event_fields=None,
-    is_invite=False,
+    include_stripped_room_state=False,
 ):
     """Serialize event for clients
 
@@ -275,8 +276,10 @@ def serialize_event(
         event_format
         token_id
         only_event_fields
-        is_invite (bool): Whether this is an invite that is being sent to the
-            invitee
+        include_stripped_room_state (bool): Some events can have stripped room state
+            stored in the `unsigned` field. This is required for invite and knock
+            functionality. If this option is False, that state will be removed from the
+            event before it is returned. Otherwise, it will be kept.
 
     Returns:
         dict
@@ -308,11 +311,13 @@ def serialize_event(
             if txn_id is not None:
                 d["unsigned"]["transaction_id"] = txn_id
 
-    # If this is an invite for somebody else, then we don't care about the
-    # invite_room_state as that's meant solely for the invitee. Other clients
-    # will already have the state since they're in the room.
-    if not is_invite:
+    # invite_room_state and knock_room_state are a list of stripped room state events
+    # that are meant to provide metadata about a room to an invitee/knocker. They are
+    # intended to only be included in specific circumstances, such as down sync, and
+    # should not be included in any other case.
+    if not include_stripped_room_state:
         d["unsigned"].pop("invite_room_state", None)
+        d["unsigned"].pop("knock_room_state", None)
 
     if as_client_event:
         d = event_format(d)