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https://git.anonymousland.org/anonymousland/synapse.git
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27c375f812
This should help ensure that equivalent results are achieved between homeservers querying for the summary of a space. This implements modified MSC1772 rules, according to MSC2946. The different is that the origin_server_ts of the m.room.create event is not used as a tie-breaker since this might not be known if the homeserver is not part of the room.
467 lines
16 KiB
Python
467 lines
16 KiB
Python
# 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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import itertools
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import logging
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import re
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from collections import deque
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from typing import TYPE_CHECKING, Iterable, List, Optional, Sequence, Set, Tuple, cast
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import attr
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from synapse.api.constants import EventContentFields, EventTypes, HistoryVisibility
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from synapse.api.errors import AuthError
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from synapse.events import EventBase
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from synapse.events.utils import format_event_for_client_v2
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from synapse.types import JsonDict
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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# number of rooms to return. We'll stop once we hit this limit.
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# TODO: allow clients to reduce this with a request param.
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MAX_ROOMS = 50
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# max number of events to return per room.
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MAX_ROOMS_PER_SPACE = 50
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# max number of federation servers to hit per room
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MAX_SERVERS_PER_SPACE = 3
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class SpaceSummaryHandler:
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def __init__(self, hs: "HomeServer"):
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self._clock = hs.get_clock()
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self._auth = hs.get_auth()
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self._room_list_handler = hs.get_room_list_handler()
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self._state_handler = hs.get_state_handler()
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self._store = hs.get_datastore()
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self._event_serializer = hs.get_event_client_serializer()
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self._server_name = hs.hostname
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self._federation_client = hs.get_federation_client()
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async def get_space_summary(
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self,
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requester: str,
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room_id: str,
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suggested_only: bool = False,
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max_rooms_per_space: Optional[int] = None,
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) -> JsonDict:
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"""
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Implementation of the space summary C-S API
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Args:
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requester: user id of the user making this request
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room_id: room id to start the summary at
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suggested_only: whether we should only return children with the "suggested"
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flag set.
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max_rooms_per_space: an optional limit on the number of child rooms we will
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return. This does not apply to the root room (ie, room_id), and
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is overridden by MAX_ROOMS_PER_SPACE.
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Returns:
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summary dict to return
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"""
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# first of all, check that the user is in the room in question (or it's
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# world-readable)
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await self._auth.check_user_in_room_or_world_readable(room_id, requester)
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# the queue of rooms to process
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room_queue = deque((_RoomQueueEntry(room_id, ()),))
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# rooms we have already processed
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processed_rooms = set() # type: Set[str]
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# events we have already processed. We don't necessarily have their event ids,
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# so instead we key on (room id, state key)
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processed_events = set() # type: Set[Tuple[str, str]]
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rooms_result = [] # type: List[JsonDict]
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events_result = [] # type: List[JsonDict]
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while room_queue and len(rooms_result) < MAX_ROOMS:
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queue_entry = room_queue.popleft()
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room_id = queue_entry.room_id
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if room_id in processed_rooms:
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# already done this room
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continue
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logger.debug("Processing room %s", room_id)
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is_in_room = await self._store.is_host_joined(room_id, self._server_name)
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# The client-specified max_rooms_per_space limit doesn't apply to the
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# room_id specified in the request, so we ignore it if this is the
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# first room we are processing.
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max_children = max_rooms_per_space if processed_rooms else None
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if is_in_room:
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rooms, events = await self._summarize_local_room(
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requester, room_id, suggested_only, max_children
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)
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else:
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rooms, events = await self._summarize_remote_room(
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queue_entry,
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suggested_only,
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max_children,
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exclude_rooms=processed_rooms,
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)
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logger.debug(
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"Query of %s returned rooms %s, events %s",
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queue_entry.room_id,
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[room.get("room_id") for room in rooms],
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["%s->%s" % (ev["room_id"], ev["state_key"]) for ev in events],
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)
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rooms_result.extend(rooms)
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# any rooms returned don't need visiting again
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processed_rooms.update(cast(str, room.get("room_id")) for room in rooms)
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# the room we queried may or may not have been returned, but don't process
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# it again, anyway.
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processed_rooms.add(room_id)
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# XXX: is it ok that we blindly iterate through any events returned by
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# a remote server, whether or not they actually link to any rooms in our
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# tree?
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for ev in events:
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# remote servers might return events we have already processed
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# (eg, Dendrite returns inward pointers as well as outward ones), so
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# we need to filter them out, to avoid returning duplicate links to the
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# client.
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ev_key = (ev["room_id"], ev["state_key"])
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if ev_key in processed_events:
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continue
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events_result.append(ev)
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# add the child to the queue. we have already validated
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# that the vias are a list of server names.
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room_queue.append(
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_RoomQueueEntry(ev["state_key"], ev["content"]["via"])
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)
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processed_events.add(ev_key)
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return {"rooms": rooms_result, "events": events_result}
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async def federation_space_summary(
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self,
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room_id: str,
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suggested_only: bool,
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max_rooms_per_space: Optional[int],
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exclude_rooms: Iterable[str],
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) -> JsonDict:
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"""
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Implementation of the space summary Federation API
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Args:
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room_id: room id to start the summary at
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suggested_only: whether we should only return children with the "suggested"
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flag set.
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max_rooms_per_space: an optional limit on the number of child rooms we will
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return. Unlike the C-S API, this applies to the root room (room_id).
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It is clipped to MAX_ROOMS_PER_SPACE.
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exclude_rooms: a list of rooms to skip over (presumably because the
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calling server has already seen them).
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Returns:
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summary dict to return
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"""
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# the queue of rooms to process
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room_queue = deque((room_id,))
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# the set of rooms that we should not walk further. Initialise it with the
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# excluded-rooms list; we will add other rooms as we process them so that
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# we do not loop.
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processed_rooms = set(exclude_rooms) # type: Set[str]
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rooms_result = [] # type: List[JsonDict]
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events_result = [] # type: List[JsonDict]
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while room_queue and len(rooms_result) < MAX_ROOMS:
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room_id = room_queue.popleft()
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if room_id in processed_rooms:
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# already done this room
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continue
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logger.debug("Processing room %s", room_id)
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rooms, events = await self._summarize_local_room(
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None, room_id, suggested_only, max_rooms_per_space
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)
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processed_rooms.add(room_id)
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rooms_result.extend(rooms)
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events_result.extend(events)
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# add any children to the queue
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room_queue.extend(edge_event["state_key"] for edge_event in events)
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return {"rooms": rooms_result, "events": events_result}
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async def _summarize_local_room(
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self,
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requester: Optional[str],
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room_id: str,
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suggested_only: bool,
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max_children: Optional[int],
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) -> Tuple[Sequence[JsonDict], Sequence[JsonDict]]:
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"""
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Generate a room entry and a list of event entries for a given room.
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Args:
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requester: The requesting user, or None if this is over federation.
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room_id: The room ID to summarize.
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suggested_only: True if only suggested children should be returned.
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Otherwise, all children are returned.
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max_children: The maximum number of children to return for this node.
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Returns:
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A tuple of:
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An iterable of a single value of the room.
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An iterable of the sorted children events. This may be limited
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to a maximum size or may include all children.
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"""
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if not await self._is_room_accessible(room_id, requester):
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return (), ()
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room_entry = await self._build_room_entry(room_id)
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# look for child rooms/spaces.
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child_events = await self._get_child_events(room_id)
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if suggested_only:
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# we only care about suggested children
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child_events = filter(_is_suggested_child_event, child_events)
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if max_children is None or max_children > MAX_ROOMS_PER_SPACE:
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max_children = MAX_ROOMS_PER_SPACE
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now = self._clock.time_msec()
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events_result = [] # type: List[JsonDict]
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for edge_event in itertools.islice(child_events, max_children):
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events_result.append(
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await self._event_serializer.serialize_event(
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edge_event,
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time_now=now,
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event_format=format_event_for_client_v2,
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)
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)
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return (room_entry,), events_result
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async def _summarize_remote_room(
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self,
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room: "_RoomQueueEntry",
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suggested_only: bool,
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max_children: Optional[int],
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exclude_rooms: Iterable[str],
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) -> Tuple[Sequence[JsonDict], Sequence[JsonDict]]:
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room_id = room.room_id
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logger.info("Requesting summary for %s via %s", room_id, room.via)
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# we need to make the exclusion list json-serialisable
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exclude_rooms = list(exclude_rooms)
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via = itertools.islice(room.via, MAX_SERVERS_PER_SPACE)
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try:
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res = await self._federation_client.get_space_summary(
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via,
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room_id,
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suggested_only=suggested_only,
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max_rooms_per_space=max_children,
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exclude_rooms=exclude_rooms,
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)
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except Exception as e:
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logger.warning(
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"Unable to get summary of %s via federation: %s",
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room_id,
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e,
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exc_info=logger.isEnabledFor(logging.DEBUG),
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)
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return (), ()
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return res.rooms, tuple(
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ev.data
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for ev in res.events
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if ev.event_type == EventTypes.MSC1772_SPACE_CHILD
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or ev.event_type == EventTypes.SpaceChild
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)
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async def _is_room_accessible(self, room_id: str, requester: Optional[str]) -> bool:
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# if we have an authenticated requesting user, first check if they are in the
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# room
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if requester:
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try:
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await self._auth.check_user_in_room(room_id, requester)
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return True
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except AuthError:
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pass
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# otherwise, check if the room is peekable
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hist_vis_ev = await self._state_handler.get_current_state(
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room_id, EventTypes.RoomHistoryVisibility, ""
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)
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if hist_vis_ev:
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hist_vis = hist_vis_ev.content.get("history_visibility")
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if hist_vis == HistoryVisibility.WORLD_READABLE:
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return True
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logger.info(
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"room %s is unpeekable and user %s is not a member, omitting from summary",
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room_id,
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requester,
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)
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return False
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async def _build_room_entry(self, room_id: str) -> JsonDict:
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"""Generate en entry suitable for the 'rooms' list in the summary response"""
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stats = await self._store.get_room_with_stats(room_id)
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# currently this should be impossible because we call
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# check_user_in_room_or_world_readable on the room before we get here, so
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# there should always be an entry
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assert stats is not None, "unable to retrieve stats for %s" % (room_id,)
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current_state_ids = await self._store.get_current_state_ids(room_id)
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create_event = await self._store.get_event(
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current_state_ids[(EventTypes.Create, "")]
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)
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# TODO: update once MSC1772 lands
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room_type = create_event.content.get(EventContentFields.ROOM_TYPE)
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if not room_type:
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room_type = create_event.content.get(EventContentFields.MSC1772_ROOM_TYPE)
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entry = {
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"room_id": stats["room_id"],
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"name": stats["name"],
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"topic": stats["topic"],
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"canonical_alias": stats["canonical_alias"],
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"num_joined_members": stats["joined_members"],
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"avatar_url": stats["avatar"],
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"world_readable": (
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stats["history_visibility"] == HistoryVisibility.WORLD_READABLE
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),
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"guest_can_join": stats["guest_access"] == "can_join",
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"creation_ts": create_event.origin_server_ts,
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"room_type": room_type,
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}
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# Filter out Nones – rather omit the field altogether
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room_entry = {k: v for k, v in entry.items() if v is not None}
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return room_entry
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async def _get_child_events(self, room_id: str) -> Iterable[EventBase]:
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"""
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Get the child events for a given room.
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The returned results are sorted for stability.
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Args:
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room_id: The room id to get the children of.
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Returns:
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An iterable of sorted child events.
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"""
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# look for child rooms/spaces.
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current_state_ids = await self._store.get_current_state_ids(room_id)
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events = await self._store.get_events_as_list(
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[
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event_id
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for key, event_id in current_state_ids.items()
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# TODO: update once MSC1772 has been FCP for a period of time.
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if key[0] == EventTypes.MSC1772_SPACE_CHILD
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or key[0] == EventTypes.SpaceChild
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]
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)
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# filter out any events without a "via" (which implies it has been redacted),
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# and order to ensure we return stable results.
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return sorted(filter(_has_valid_via, events), key=_child_events_comparison_key)
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@attr.s(frozen=True, slots=True)
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class _RoomQueueEntry:
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room_id = attr.ib(type=str)
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via = attr.ib(type=Sequence[str])
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def _has_valid_via(e: EventBase) -> bool:
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via = e.content.get("via")
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if not via or not isinstance(via, Sequence):
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return False
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for v in via:
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if not isinstance(v, str):
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logger.debug("Ignoring edge event %s with invalid via entry", e.event_id)
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return False
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return True
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def _is_suggested_child_event(edge_event: EventBase) -> bool:
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suggested = edge_event.content.get("suggested")
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if isinstance(suggested, bool) and suggested:
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return True
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logger.debug("Ignorning not-suggested child %s", edge_event.state_key)
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return False
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# Order may only contain characters in the range of \x20 (space) to \x7F (~).
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_INVALID_ORDER_CHARS_RE = re.compile(r"[^\x20-\x7F]")
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def _child_events_comparison_key(child: EventBase) -> Tuple[bool, Optional[str], str]:
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"""
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Generate a value for comparing two child events for ordering.
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The rules for ordering are supposed to be:
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1. The 'order' key, if it is valid.
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2. The 'origin_server_ts' of the 'm.room.create' event.
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3. The 'room_id'.
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But we skip step 2 since we may not have any state from the room.
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Args:
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child: The event for generating a comparison key.
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Returns:
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The comparison key as a tuple of:
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False if the ordering is valid.
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The ordering field.
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The room ID.
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"""
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order = child.content.get("order")
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# If order is not a string or doesn't meet the requirements, ignore it.
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if not isinstance(order, str):
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order = None
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elif len(order) > 50 or _INVALID_ORDER_CHARS_RE.search(order):
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order = None
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# Items without an order come last.
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return (order is None, order, child.room_id)
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