synapse-old/synapse/handlers/space_summary.py

467 lines
16 KiB
Python
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

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