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- # -*- coding: utf-8 -*-
- # Copyright 2014 - 2016 OpenMarket Ltd
- #
- # 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 operator
- from twisted.internet import defer
- from synapse.api.constants import EventTypes, Membership
- from synapse.events.utils import prune_event
- from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
- logger = logging.getLogger(__name__)
- VISIBILITY_PRIORITY = (
- "world_readable",
- "shared",
- "invited",
- "joined",
- )
- MEMBERSHIP_PRIORITY = (
- Membership.JOIN,
- Membership.INVITE,
- Membership.KNOCK,
- Membership.LEAVE,
- Membership.BAN,
- )
- @defer.inlineCallbacks
- def filter_events_for_client(store, user_id, events, is_peeking=False,
- always_include_ids=frozenset()):
- """
- Check which events a user is allowed to see
- Args:
- store (synapse.storage.DataStore): our datastore (can also be a worker
- store)
- user_id(str): user id to be checked
- events(list[synapse.events.EventBase]): sequence of events to be checked
- is_peeking(bool): should be True if:
- * the user is not currently a member of the room, and:
- * the user has not been a member of the room since the given
- events
- always_include_ids (set(event_id)): set of event ids to specifically
- include (unless sender is ignored)
- Returns:
- Deferred[list[synapse.events.EventBase]]
- """
- types = (
- (EventTypes.RoomHistoryVisibility, ""),
- (EventTypes.Member, user_id),
- )
- event_id_to_state = yield store.get_state_for_events(
- frozenset(e.event_id for e in events),
- types=types,
- )
- forgotten = yield make_deferred_yieldable(defer.gatherResults([
- defer.maybeDeferred(
- preserve_fn(store.who_forgot_in_room),
- room_id,
- )
- for room_id in frozenset(e.room_id for e in events)
- ], consumeErrors=True))
- # Set of membership event_ids that have been forgotten
- event_id_forgotten = frozenset(
- row["event_id"] for rows in forgotten for row in rows
- )
- ignore_dict_content = yield store.get_global_account_data_by_type_for_user(
- "m.ignored_user_list", user_id,
- )
- # FIXME: This will explode if people upload something incorrect.
- ignore_list = frozenset(
- ignore_dict_content.get("ignored_users", {}).keys()
- if ignore_dict_content else []
- )
- erased_senders = yield store.are_users_erased((e.sender for e in events))
- def allowed(event):
- """
- Args:
- event (synapse.events.EventBase): event to check
- Returns:
- None|EventBase:
- None if the user cannot see this event at all
- a redacted copy of the event if they can only see a redacted
- version
- the original event if they can see it as normal.
- """
- if not event.is_state() and event.sender in ignore_list:
- return None
- if event.event_id in always_include_ids:
- return event
- state = event_id_to_state[event.event_id]
- # get the room_visibility at the time of the event.
- visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
- if visibility_event:
- visibility = visibility_event.content.get("history_visibility", "shared")
- else:
- visibility = "shared"
- if visibility not in VISIBILITY_PRIORITY:
- visibility = "shared"
- # Always allow history visibility events on boundaries. This is done
- # by setting the effective visibility to the least restrictive
- # of the old vs new.
- if event.type == EventTypes.RoomHistoryVisibility:
- prev_content = event.unsigned.get("prev_content", {})
- prev_visibility = prev_content.get("history_visibility", None)
- if prev_visibility not in VISIBILITY_PRIORITY:
- prev_visibility = "shared"
- new_priority = VISIBILITY_PRIORITY.index(visibility)
- old_priority = VISIBILITY_PRIORITY.index(prev_visibility)
- if old_priority < new_priority:
- visibility = prev_visibility
- # likewise, if the event is the user's own membership event, use
- # the 'most joined' membership
- membership = None
- if event.type == EventTypes.Member and event.state_key == user_id:
- membership = event.content.get("membership", None)
- if membership not in MEMBERSHIP_PRIORITY:
- membership = "leave"
- prev_content = event.unsigned.get("prev_content", {})
- prev_membership = prev_content.get("membership", None)
- if prev_membership not in MEMBERSHIP_PRIORITY:
- prev_membership = "leave"
- # Always allow the user to see their own leave events, otherwise
- # they won't see the room disappear if they reject the invite
- if membership == "leave" and (
- prev_membership == "join" or prev_membership == "invite"
- ):
- return event
- new_priority = MEMBERSHIP_PRIORITY.index(membership)
- old_priority = MEMBERSHIP_PRIORITY.index(prev_membership)
- if old_priority < new_priority:
- membership = prev_membership
- # otherwise, get the user's membership at the time of the event.
- if membership is None:
- membership_event = state.get((EventTypes.Member, user_id), None)
- if membership_event:
- # XXX why do we do this?
- # https://github.com/matrix-org/synapse/issues/3350
- if membership_event.event_id not in event_id_forgotten:
- membership = membership_event.membership
- # if the user was a member of the room at the time of the event,
- # they can see it.
- if membership == Membership.JOIN:
- return event
- # otherwise, it depends on the room visibility.
- if visibility == "joined":
- # we weren't a member at the time of the event, so we can't
- # see this event.
- return None
- elif visibility == "invited":
- # user can also see the event if they were *invited* at the time
- # of the event.
- return (
- event if membership == Membership.INVITE else None
- )
- elif visibility == "shared" and is_peeking:
- # if the visibility is shared, users cannot see the event unless
- # they have *subequently* joined the room (or were members at the
- # time, of course)
- #
- # XXX: if the user has subsequently joined and then left again,
- # ideally we would share history up to the point they left. But
- # we don't know when they left. We just treat it as though they
- # never joined, and restrict access.
- return None
- # the visibility is either shared or world_readable, and the user was
- # not a member at the time. We allow it, provided the original sender
- # has not requested their data to be erased, in which case, we return
- # a redacted version.
- if erased_senders[event.sender]:
- return prune_event(event)
- return event
- # check each event: gives an iterable[None|EventBase]
- filtered_events = itertools.imap(allowed, events)
- # remove the None entries
- filtered_events = filter(operator.truth, filtered_events)
- # we turn it into a list before returning it.
- defer.returnValue(list(filtered_events))
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