forked from MirrorHub/synapse
Check for space membership during a remote join of a restricted room (#9814)
When receiving a /send_join request for a room with join rules set to 'restricted', check if the user is a member of the spaces defined in the 'allow' key of the join rules. This only applies to an experimental room version, as defined in MSC3083.
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changelog.d/9814.feature
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changelog.d/9814.feature
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Update experimental support for [MSC3083](https://github.com/matrix-org/matrix-doc/pull/3083): restricting room access via group membership.
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@ -65,6 +65,7 @@ class Auth:
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"""
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FIXME: This class contains a mix of functions for authenticating users
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of our client-server API and authenticating events added to room graphs.
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The latter should be moved to synapse.handlers.event_auth.EventAuthHandler.
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"""
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def __init__(self, hs):
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86
synapse/handlers/event_auth.py
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86
synapse/handlers/event_auth.py
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# Copyright 2021 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from typing import TYPE_CHECKING
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from synapse.api.constants import EventTypes, JoinRules
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from synapse.api.room_versions import RoomVersion
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from synapse.types import StateMap
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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class EventAuthHandler:
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"""
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This class contains methods for authenticating events added to room graphs.
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"""
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def __init__(self, hs: "HomeServer"):
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self._store = hs.get_datastore()
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async def can_join_without_invite(
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self, state_ids: StateMap[str], room_version: RoomVersion, user_id: str
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) -> bool:
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"""
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Check whether a user can join a room without an invite.
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When joining a room with restricted joined rules (as defined in MSC3083),
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the membership of spaces must be checked during join.
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Args:
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state_ids: The state of the room as it currently is.
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room_version: The room version of the room being joined.
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user_id: The user joining the room.
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Returns:
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True if the user can join the room, false otherwise.
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"""
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# This only applies to room versions which support the new join rule.
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if not room_version.msc3083_join_rules:
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return True
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# If there's no join rule, then it defaults to invite (so this doesn't apply).
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join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""), None)
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if not join_rules_event_id:
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return True
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# If the join rule is not restricted, this doesn't apply.
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join_rules_event = await self._store.get_event(join_rules_event_id)
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if join_rules_event.content.get("join_rule") != JoinRules.MSC3083_RESTRICTED:
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return True
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# If allowed is of the wrong form, then only allow invited users.
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allowed_spaces = join_rules_event.content.get("allow", [])
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if not isinstance(allowed_spaces, list):
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return False
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# Get the list of joined rooms and see if there's an overlap.
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joined_rooms = await self._store.get_rooms_for_user(user_id)
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# Pull out the other room IDs, invalid data gets filtered.
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for space in allowed_spaces:
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if not isinstance(space, dict):
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continue
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space_id = space.get("space")
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if not isinstance(space_id, str):
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continue
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# The user was joined to one of the spaces specified, they can join
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# this room!
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if space_id in joined_rooms:
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return True
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# The user was not in any of the required spaces.
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return False
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@ -146,6 +146,7 @@ class FederationHandler(BaseHandler):
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self.is_mine_id = hs.is_mine_id
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self.spam_checker = hs.get_spam_checker()
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self.event_creation_handler = hs.get_event_creation_handler()
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self._event_auth_handler = hs.get_event_auth_handler()
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self._message_handler = hs.get_message_handler()
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self._server_notices_mxid = hs.config.server_notices_mxid
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self.config = hs.config
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@ -1673,8 +1674,40 @@ class FederationHandler(BaseHandler):
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# would introduce the danger of backwards-compatibility problems.
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event.internal_metadata.send_on_behalf_of = origin
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# Calculate the event context.
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context = await self.state_handler.compute_event_context(event)
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context = await self._auth_and_persist_event(origin, event, context)
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# Get the state before the new event.
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prev_state_ids = await context.get_prev_state_ids()
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# Check if the user is already in the room or invited to the room.
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user_id = event.state_key
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prev_member_event_id = prev_state_ids.get((EventTypes.Member, user_id), None)
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newly_joined = True
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user_is_invited = False
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if prev_member_event_id:
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prev_member_event = await self.store.get_event(prev_member_event_id)
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newly_joined = prev_member_event.membership != Membership.JOIN
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user_is_invited = prev_member_event.membership == Membership.INVITE
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# If the member is not already in the room, and not invited, check if
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# they should be allowed access via membership in a space.
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if (
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newly_joined
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and not user_is_invited
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and not await self._event_auth_handler.can_join_without_invite(
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prev_state_ids,
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event.room_version,
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user_id,
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)
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):
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raise AuthError(
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403,
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"You do not belong to any of the required spaces to join this room.",
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)
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# Persist the event.
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await self._auth_and_persist_event(origin, event, context)
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logger.debug(
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"on_send_join_request: After _auth_and_persist_event: %s, sigs: %s",
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@ -1682,8 +1715,6 @@ class FederationHandler(BaseHandler):
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event.signatures,
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)
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prev_state_ids = await context.get_prev_state_ids()
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state_ids = list(prev_state_ids.values())
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auth_chain = await self.store.get_auth_chain(event.room_id, state_ids)
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@ -2006,7 +2037,7 @@ class FederationHandler(BaseHandler):
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state: Optional[Iterable[EventBase]] = None,
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auth_events: Optional[MutableStateMap[EventBase]] = None,
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backfilled: bool = False,
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) -> EventContext:
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) -> None:
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"""
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Process an event by performing auth checks and then persisting to the database.
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@ -2028,9 +2059,6 @@ class FederationHandler(BaseHandler):
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event is an outlier), may be the auth events claimed by the remote
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server.
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backfilled: True if the event was backfilled.
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Returns:
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The event context.
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"""
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context = await self._check_event_auth(
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origin,
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)
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raise
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return context
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async def _auth_and_persist_events(
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self,
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origin: str,
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@ -19,7 +19,7 @@ from http import HTTPStatus
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from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple
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from synapse import types
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from synapse.api.constants import AccountDataTypes, EventTypes, JoinRules, Membership
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from synapse.api.constants import AccountDataTypes, EventTypes, Membership
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from synapse.api.errors import (
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AuthError,
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Codes,
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SynapseError,
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)
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from synapse.api.ratelimiting import Ratelimiter
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from synapse.api.room_versions import RoomVersion
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from synapse.events import EventBase
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from synapse.events.snapshot import EventContext
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from synapse.types import JsonDict, Requester, RoomAlias, RoomID, StateMap, UserID
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@ -64,6 +63,7 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
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self.profile_handler = hs.get_profile_handler()
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self.event_creation_handler = hs.get_event_creation_handler()
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self.account_data_handler = hs.get_account_data_handler()
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self.event_auth_handler = hs.get_event_auth_handler()
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self.member_linearizer = Linearizer(name="member")
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@ -178,62 +178,6 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
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await self._invites_per_user_limiter.ratelimit(requester, invitee_user_id)
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async def _can_join_without_invite(
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self, state_ids: StateMap[str], room_version: RoomVersion, user_id: str
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) -> bool:
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"""
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Check whether a user can join a room without an invite.
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When joining a room with restricted joined rules (as defined in MSC3083),
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the membership of spaces must be checked during join.
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Args:
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state_ids: The state of the room as it currently is.
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room_version: The room version of the room being joined.
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user_id: The user joining the room.
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Returns:
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True if the user can join the room, false otherwise.
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"""
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# This only applies to room versions which support the new join rule.
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if not room_version.msc3083_join_rules:
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return True
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# If there's no join rule, then it defaults to public (so this doesn't apply).
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join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""), None)
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if not join_rules_event_id:
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return True
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# If the join rule is not restricted, this doesn't apply.
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join_rules_event = await self.store.get_event(join_rules_event_id)
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if join_rules_event.content.get("join_rule") != JoinRules.MSC3083_RESTRICTED:
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return True
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# If allowed is of the wrong form, then only allow invited users.
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allowed_spaces = join_rules_event.content.get("allow", [])
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if not isinstance(allowed_spaces, list):
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return False
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# Get the list of joined rooms and see if there's an overlap.
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joined_rooms = await self.store.get_rooms_for_user(user_id)
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# Pull out the other room IDs, invalid data gets filtered.
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for space in allowed_spaces:
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if not isinstance(space, dict):
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continue
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space_id = space.get("space")
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if not isinstance(space_id, str):
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continue
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# The user was joined to one of the spaces specified, they can join
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# this room!
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if space_id in joined_rooms:
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return True
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# The user was not in any of the required spaces.
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return False
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async def _local_membership_update(
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self,
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requester: Requester,
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if (
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newly_joined
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and not user_is_invited
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and not await self._can_join_without_invite(
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and not await self.event_auth_handler.can_join_without_invite(
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prev_state_ids, event.room_version, user_id
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)
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):
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@ -77,6 +77,7 @@ from synapse.handlers.devicemessage import DeviceMessageHandler
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from synapse.handlers.directory import DirectoryHandler
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from synapse.handlers.e2e_keys import E2eKeysHandler
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from synapse.handlers.e2e_room_keys import E2eRoomKeysHandler
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from synapse.handlers.event_auth import EventAuthHandler
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from synapse.handlers.events import EventHandler, EventStreamHandler
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from synapse.handlers.federation import FederationHandler
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from synapse.handlers.groups_local import GroupsLocalHandler, GroupsLocalWorkerHandler
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@ -746,6 +747,10 @@ class HomeServer(metaclass=abc.ABCMeta):
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def get_space_summary_handler(self) -> SpaceSummaryHandler:
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return SpaceSummaryHandler(self)
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@cache_in_self
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def get_event_auth_handler(self) -> EventAuthHandler:
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return EventAuthHandler(self)
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@cache_in_self
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def get_external_cache(self) -> ExternalCache:
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return ExternalCache(self)
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