synapse-product/synapse/handlers/space_summary.py
Patrick Cloke 3b354faad0
Refactoring before implementing the updated spaces summary. (#10527)
This should have no user-visible changes, but refactors some pieces of
the SpaceSummaryHandler before adding support for the updated
MSC2946.
2021-08-05 12:39:17 +00:00

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# 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,
Collection,
Dict,
Iterable,
List,
Optional,
Sequence,
Set,
Tuple,
)
import attr
from synapse.api.constants import (
EventContentFields,
EventTypes,
HistoryVisibility,
JoinRules,
Membership,
RoomTypes,
)
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.
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._event_auth_handler = hs.get_event_auth_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[str] = set()
# 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[Tuple[str, str]] = set()
rooms_result: List[JsonDict] = []
events_result: 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:
room_entry = await self._summarize_local_room(
requester, None, room_id, suggested_only, max_children
)
events: Collection[JsonDict] = []
if room_entry:
rooms_result.append(room_entry.room)
events = room_entry.children
logger.debug(
"Query of local room %s returned events %s",
room_id,
["%s->%s" % (ev["room_id"], ev["state_key"]) for ev in events],
)
else:
fed_rooms = await self._summarize_remote_room(
queue_entry,
suggested_only,
max_children,
exclude_rooms=processed_rooms,
)
# The results over federation might include rooms that the we,
# as the requesting server, are allowed to see, but the requesting
# user is not permitted see.
#
# Filter the returned results to only what is accessible to the user.
events = []
for room_entry in fed_rooms:
room = room_entry.room
fed_room_id = room_entry.room_id
# The room should only be included in the summary if:
# a. the user is in the room;
# b. the room is world readable; or
# c. the user could join the room, e.g. the join rules
# are set to public or the user is in a space that
# has been granted access to the room.
#
# Note that we know the user is not in the root room (which is
# why the remote call was made in the first place), but the user
# could be in one of the children rooms and we just didn't know
# about the link.
# The API doesn't return the room version so assume that a
# join rule of knock is valid.
include_room = (
room.get("join_rules") in (JoinRules.PUBLIC, JoinRules.KNOCK)
or room.get("world_readable") is True
)
# Check if the user is a member of any of the allowed spaces
# from the response.
allowed_rooms = room.get("allowed_spaces")
if (
not include_room
and allowed_rooms
and isinstance(allowed_rooms, list)
):
include_room = await self._event_auth_handler.is_user_in_rooms(
allowed_rooms, requester
)
# Finally, if this isn't the requested room, check ourselves
# if we can access the room.
if not include_room and fed_room_id != queue_entry.room_id:
include_room = await self._is_room_accessible(
fed_room_id, requester, None
)
# The user can see the room, include it!
if include_room:
rooms_result.append(room)
events.extend(room_entry.children)
# All rooms returned don't need visiting again (even if the user
# didn't have access to them).
processed_rooms.add(fed_room_id)
logger.debug(
"Query of %s returned rooms %s, events %s",
room_id,
[room_entry.room.get("room_id") for room_entry in fed_rooms],
["%s->%s" % (ev["room_id"], ev["state_key"]) for ev in events],
)
# 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)
# Before returning to the client, remove the allowed_spaces key for any
# rooms.
for room in rooms_result:
room.pop("allowed_spaces", None)
return {"rooms": rooms_result, "events": events_result}
async def federation_space_summary(
self,
origin: str,
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:
origin: The server requesting the spaces summary.
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[str] = set(exclude_rooms)
rooms_result: List[JsonDict] = []
events_result: 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
room_entry = await self._summarize_local_room(
None, origin, room_id, suggested_only, max_rooms_per_space
)
processed_rooms.add(room_id)
if room_entry:
rooms_result.append(room_entry.room)
events_result.extend(room_entry.children)
# add any children to the queue
room_queue.extend(
edge_event["state_key"] for edge_event in room_entry.children
)
return {"rooms": rooms_result, "events": events_result}
async def _summarize_local_room(
self,
requester: Optional[str],
origin: Optional[str],
room_id: str,
suggested_only: bool,
max_children: Optional[int],
) -> Optional["_RoomEntry"]:
"""
Generate a room entry and a list of event entries for a given room.
Args:
requester:
The user requesting the summary, if it is a local request. None
if this is a federation request.
origin:
The server requesting the summary, if it is a federation request.
None if this is a local request.
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 rooms to include. This is capped
to a server-set limit.
Returns:
A room entry if the room should be returned. None, otherwise.
"""
if not await self._is_room_accessible(room_id, requester, origin):
return None
room_entry = await self._build_room_entry(room_id)
# If the room is not a space, return just the room information.
if room_entry.get("room_type") != RoomTypes.SPACE:
return _RoomEntry(room_id, room_entry)
# Otherwise, 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: 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 _RoomEntry(room_id, room_entry, events_result)
async def _summarize_remote_room(
self,
room: "_RoomQueueEntry",
suggested_only: bool,
max_children: Optional[int],
exclude_rooms: Iterable[str],
) -> Iterable["_RoomEntry"]:
"""
Request room entries and a list of event entries for a given room by querying a remote server.
Args:
room: The room to summarize.
suggested_only: True if only suggested children should be returned.
Otherwise, all children are returned.
max_children:
The maximum number of children rooms to include. This is capped
to a server-set limit.
exclude_rooms:
Rooms IDs which do not need to be summarized.
Returns:
An iterable of room entries.
"""
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 ()
# Group the events by their room.
children_by_room: Dict[str, List[JsonDict]] = {}
for ev in res.events:
if ev.event_type == EventTypes.SpaceChild:
children_by_room.setdefault(ev.room_id, []).append(ev.data)
# Generate the final results.
results = []
for fed_room in res.rooms:
fed_room_id = fed_room.get("room_id")
if not fed_room_id or not isinstance(fed_room_id, str):
continue
results.append(
_RoomEntry(
fed_room_id,
fed_room,
children_by_room.get(fed_room_id, []),
)
)
return results
async def _is_room_accessible(
self, room_id: str, requester: Optional[str], origin: Optional[str]
) -> bool:
"""
Calculate whether the room should be shown in the spaces summary.
It should be included if:
* The requester is joined or can join the room (per MSC3173).
* The origin server has any user that is joined or can join the room.
* The history visibility is set to world readable.
Args:
room_id: The room ID to summarize.
requester:
The user requesting the summary, if it is a local request. None
if this is a federation request.
origin:
The server requesting the summary, if it is a federation request.
None if this is a local request.
Returns:
True if the room should be included in the spaces summary.
"""
state_ids = await self._store.get_current_state_ids(room_id)
# If there's no state for the room, it isn't known.
if not state_ids:
# The user might have a pending invite for the room.
if requester and await self._store.get_invite_for_local_user_in_room(
requester, room_id
):
return True
logger.info("room %s is unknown, omitting from summary", room_id)
return False
room_version = await self._store.get_room_version(room_id)
# Include the room if it has join rules of public or knock.
join_rules_event_id = state_ids.get((EventTypes.JoinRules, ""))
if join_rules_event_id:
join_rules_event = await self._store.get_event(join_rules_event_id)
join_rule = join_rules_event.content.get("join_rule")
if join_rule == JoinRules.PUBLIC or (
room_version.msc2403_knocking and join_rule == JoinRules.KNOCK
):
return True
# Include the room if it is peekable.
hist_vis_event_id = state_ids.get((EventTypes.RoomHistoryVisibility, ""))
if hist_vis_event_id:
hist_vis_ev = await self._store.get_event(hist_vis_event_id)
hist_vis = hist_vis_ev.content.get("history_visibility")
if hist_vis == HistoryVisibility.WORLD_READABLE:
return True
# Otherwise we need to check information specific to the user or server.
# If we have an authenticated requesting user, check if they are a member
# of the room (or can join the room).
if requester:
member_event_id = state_ids.get((EventTypes.Member, requester), None)
# If they're in the room they can see info on it.
if member_event_id:
member_event = await self._store.get_event(member_event_id)
if member_event.membership in (Membership.JOIN, Membership.INVITE):
return True
# Otherwise, check if they should be allowed access via membership in a space.
if await self._event_auth_handler.has_restricted_join_rules(
state_ids, room_version
):
allowed_rooms = (
await self._event_auth_handler.get_rooms_that_allow_join(state_ids)
)
if await self._event_auth_handler.is_user_in_rooms(
allowed_rooms, requester
):
return True
# If this is a request over federation, check if the host is in the room or
# has a user who could join the room.
elif origin:
if await self._event_auth_handler.check_host_in_room(
room_id, origin
) or await self._store.is_host_invited(room_id, origin):
return True
# Alternately, if the host has a user in any of the spaces specified
# for access, then the host can see this room (and should do filtering
# if the requester cannot see it).
if await self._event_auth_handler.has_restricted_join_rules(
state_ids, room_version
):
allowed_rooms = (
await self._event_auth_handler.get_rooms_that_allow_join(state_ids)
)
for space_id in allowed_rooms:
if await self._event_auth_handler.check_host_in_room(
space_id, origin
):
return True
logger.info(
"room %s is unpeekable and requester %s is not a member / not allowed to join, omitting from summary",
room_id,
requester or origin,
)
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, "")]
)
room_version = await self._store.get_room_version(room_id)
allowed_rooms = None
if await self._event_auth_handler.has_restricted_join_rules(
current_state_ids, room_version
):
allowed_rooms = await self._event_auth_handler.get_rooms_that_allow_join(
current_state_ids
)
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"],
"join_rules": stats["join_rules"],
"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": create_event.content.get(EventContentFields.ROOM_TYPE),
"allowed_spaces": allowed_rooms,
}
# 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()
if 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, auto_attribs=True)
class _RoomQueueEntry:
room_id: str
via: Sequence[str]
@attr.s(frozen=True, slots=True, auto_attribs=True)
class _RoomEntry:
room_id: str
# The room summary for this room.
room: JsonDict
# An iterable of the sorted, stripped children events for children of this room.
#
# This may not include all children.
children: Collection[JsonDict] = ()
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 \x7E (~) inclusive.
_INVALID_ORDER_CHARS_RE = re.compile(r"[^\x20-\x7E]")
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)