diff options
Diffstat (limited to 'synapse/handlers/room_member.py')
| -rw-r--r-- | synapse/handlers/room_member.py | 175 |
1 files changed, 167 insertions, 8 deletions
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py index 1192591609..65ad3efa6a 100644 --- a/synapse/handlers/room_member.py +++ b/synapse/handlers/room_member.py @@ -16,7 +16,7 @@ import abc import logging import random from http import HTTPStatus -from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple +from typing import TYPE_CHECKING, Iterable, List, Optional, Set, Tuple from synapse import types from synapse.api.constants import AccountDataTypes, EventTypes, Membership @@ -28,6 +28,7 @@ from synapse.api.errors import ( SynapseError, ) from synapse.api.ratelimiting import Ratelimiter +from synapse.event_auth import get_named_level, get_power_level_event from synapse.events import EventBase from synapse.events.snapshot import EventContext from synapse.types import ( @@ -340,16 +341,10 @@ class RoomMemberHandler(metaclass=abc.ABCMeta): if event.membership == Membership.JOIN: newly_joined = True - prev_member_event = None if prev_member_event_id: prev_member_event = await self.store.get_event(prev_member_event_id) newly_joined = prev_member_event.membership != Membership.JOIN - # Check if the member should be allowed access via membership in a space. - await self.event_auth_handler.check_restricted_join_rules( - prev_state_ids, event.room_version, user_id, prev_member_event - ) - # Only rate-limit if the user actually joined the room, otherwise we'll end # up blocking profile updates. if newly_joined and ratelimit: @@ -701,7 +696,11 @@ class RoomMemberHandler(metaclass=abc.ABCMeta): # so don't really fit into the general auth process. raise AuthError(403, "Guest access not allowed") - if not is_host_in_room: + # Check if a remote join should be performed. + remote_join, remote_room_hosts = await self._should_perform_remote_join( + target.to_string(), room_id, remote_room_hosts, content, is_host_in_room + ) + if remote_join: if ratelimit: time_now_s = self.clock.time() ( @@ -826,6 +825,106 @@ class RoomMemberHandler(metaclass=abc.ABCMeta): outlier=outlier, ) + async def _should_perform_remote_join( + self, + user_id: str, + room_id: str, + remote_room_hosts: List[str], + content: JsonDict, + is_host_in_room: bool, + ) -> Tuple[bool, List[str]]: + """ + Check whether the server should do a remote join (as opposed to a local + join) for a user. + + Generally a remote join is used if: + + * The server is not yet in the room. + * The server is in the room, the room has restricted join rules, the user + is not joined or invited to the room, and the server does not have + another user who is capable of issuing invites. + + Args: + user_id: The user joining the room. + room_id: The room being joined. + remote_room_hosts: A list of remote room hosts. + content: The content to use as the event body of the join. This may + be modified. + is_host_in_room: True if the host is in the room. + + Returns: + A tuple of: + True if a remote join should be performed. False if the join can be + done locally. + + A list of remote room hosts to use. This is an empty list if a + local join is to be done. + """ + # If the host isn't in the room, pass through the prospective hosts. + if not is_host_in_room: + return True, remote_room_hosts + + # If the host is in the room, but not one of the authorised hosts + # for restricted join rules, a remote join must be used. + room_version = await self.store.get_room_version(room_id) + current_state_ids = await self.store.get_current_state_ids(room_id) + + # If restricted join rules are not being used, a local join can always + # be used. + if not await self.event_auth_handler.has_restricted_join_rules( + current_state_ids, room_version + ): + return False, [] + + # If the user is invited to the room or already joined, the join + # event can always be issued locally. + prev_member_event_id = current_state_ids.get((EventTypes.Member, user_id), None) + prev_member_event = None + if prev_member_event_id: + prev_member_event = await self.store.get_event(prev_member_event_id) + if prev_member_event.membership in ( + Membership.JOIN, + Membership.INVITE, + ): + return False, [] + + # If the local host has a user who can issue invites, then a local + # join can be done. + # + # If not, generate a new list of remote hosts based on which + # can issue invites. + event_map = await self.store.get_events(current_state_ids.values()) + current_state = { + state_key: event_map[event_id] + for state_key, event_id in current_state_ids.items() + } + allowed_servers = get_servers_from_users( + get_users_which_can_issue_invite(current_state) + ) + + # If the local server is not one of allowed servers, then a remote + # join must be done. Return the list of prospective servers based on + # which can issue invites. + if self.hs.hostname not in allowed_servers: + return True, list(allowed_servers) + + # Ensure the member should be allowed access via membership in a room. + await self.event_auth_handler.check_restricted_join_rules( + current_state_ids, room_version, user_id, prev_member_event + ) + + # If this is going to be a local join, additional information must + # be included in the event content in order to efficiently validate + # the event. + content[ + "join_authorised_via_users_server" + ] = await self.event_auth_handler.get_user_which_could_invite( + room_id, + current_state_ids, + ) + + return False, [] + async def transfer_room_state_on_room_upgrade( self, old_room_id: str, room_id: str ) -> None: @@ -1514,3 +1613,63 @@ class RoomMemberMasterHandler(RoomMemberHandler): if membership: await self.store.forget(user_id, room_id) + + +def get_users_which_can_issue_invite(auth_events: StateMap[EventBase]) -> List[str]: + """ + Return the list of users which can issue invites. + + This is done by exploring the joined users and comparing their power levels + to the necessyar power level to issue an invite. + + Args: + auth_events: state in force at this point in the room + + Returns: + The users which can issue invites. + """ + invite_level = get_named_level(auth_events, "invite", 0) + users_default_level = get_named_level(auth_events, "users_default", 0) + power_level_event = get_power_level_event(auth_events) + + # Custom power-levels for users. + if power_level_event: + users = power_level_event.content.get("users", {}) + else: + users = {} + + result = [] + + # Check which members are able to invite by ensuring they're joined and have + # the necessary power level. + for (event_type, state_key), event in auth_events.items(): + if event_type != EventTypes.Member: + continue + + if event.membership != Membership.JOIN: + continue + + # Check if the user has a custom power level. + if users.get(state_key, users_default_level) >= invite_level: + result.append(state_key) + + return result + + +def get_servers_from_users(users: List[str]) -> Set[str]: + """ + Resolve a list of users into their servers. + + Args: + users: A list of users. + + Returns: + A set of servers. + """ + servers = set() + for user in users: + try: + servers.add(get_domain_from_id(user)) + except SynapseError: + pass + return servers |