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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 logging
- import operator
- from six import iteritems, itervalues
- from six.moves import map
- from twisted.internet import defer
- from synapse.api.constants import EventTypes, Membership
- from synapse.events.utils import prune_event
- from synapse.storage import Storage
- from synapse.storage.state import StateFilter
- from synapse.types import get_domain_from_id
- 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(
- storage: Storage,
- user_id,
- events,
- is_peeking=False,
- always_include_ids=frozenset(),
- filter_send_to_client=True,
- ):
- """
- Check which events a user is allowed to see. If the user can see the event but its
- sender asked for their data to be erased, prune the content of the event.
- Args:
- storage
- 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)
- filter_send_to_client (bool): Whether we're checking an event that's going to be
- sent to a client. This might not always be the case since this function can
- also be called to check whether a user can see the state at a given point.
- Returns:
- Deferred[list[synapse.events.EventBase]]
- """
- # Filter out events that have been soft failed so that we don't relay them
- # to clients.
- events = [e for e in events if not e.internal_metadata.is_soft_failed()]
- types = ((EventTypes.RoomHistoryVisibility, ""), (EventTypes.Member, user_id))
- event_id_to_state = yield storage.state.get_state_for_events(
- frozenset(e.event_id for e in events),
- state_filter=StateFilter.from_types(types),
- )
- ignore_dict_content = yield storage.main.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 storage.main.are_users_erased((e.sender for e in events))
- if filter_send_to_client:
- room_ids = {e.room_id for e in events}
- retention_policies = {}
- for room_id in room_ids:
- retention_policies[
- room_id
- ] = yield storage.main.get_retention_policy_for_room(room_id)
- 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.
- """
- # Only run some checks if these events aren't about to be sent to clients. This is
- # because, if this is not the case, we're probably only checking if the users can
- # see events in the room at that point in the DAG, and that shouldn't be decided
- # on those checks.
- if filter_send_to_client:
- if event.type == "org.matrix.dummy_event":
- return None
- if not event.is_state() and event.sender in ignore_list:
- return None
- # Until MSC2261 has landed we can't redact malicious alias events, so for
- # now we temporarily filter out m.room.aliases entirely to mitigate
- # abuse, while we spec a better solution to advertising aliases
- # on rooms.
- if event.type == EventTypes.Aliases:
- return None
- # Don't try to apply the room's retention policy if the event is a state
- # event, as MSC1763 states that retention is only considered for non-state
- # events.
- if not event.is_state():
- retention_policy = retention_policies[event.room_id]
- max_lifetime = retention_policy.get("max_lifetime")
- if max_lifetime is not None:
- oldest_allowed_ts = storage.main.clock.time_msec() - max_lifetime
- if event.origin_server_ts < oldest_allowed_ts:
- 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:
- 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 = map(allowed, events)
- # remove the None entries
- filtered_events = filter(operator.truth, filtered_events)
- # we turn it into a list before returning it.
- return list(filtered_events)
- @defer.inlineCallbacks
- def filter_events_for_server(
- storage: Storage,
- server_name,
- events,
- redact=True,
- check_history_visibility_only=False,
- ):
- """Filter a list of events based on whether given server is allowed to
- see them.
- Args:
- storage
- server_name (str)
- events (iterable[FrozenEvent])
- redact (bool): Whether to return a redacted version of the event, or
- to filter them out entirely.
- check_history_visibility_only (bool): Whether to only check the
- history visibility, rather than things like if the sender has been
- erased. This is used e.g. during pagination to decide whether to
- backfill or not.
- Returns
- Deferred[list[FrozenEvent]]
- """
- def is_sender_erased(event, erased_senders):
- if erased_senders and erased_senders[event.sender]:
- logger.info("Sender of %s has been erased, redacting", event.event_id)
- return True
- return False
- def check_event_is_visible(event, state):
- history = state.get((EventTypes.RoomHistoryVisibility, ""), None)
- if history:
- visibility = history.content.get("history_visibility", "shared")
- if visibility in ["invited", "joined"]:
- # We now loop through all state events looking for
- # membership states for the requesting server to determine
- # if the server is either in the room or has been invited
- # into the room.
- for ev in itervalues(state):
- if ev.type != EventTypes.Member:
- continue
- try:
- domain = get_domain_from_id(ev.state_key)
- except Exception:
- continue
- if domain != server_name:
- continue
- memtype = ev.membership
- if memtype == Membership.JOIN:
- return True
- elif memtype == Membership.INVITE:
- if visibility == "invited":
- return True
- else:
- # server has no users in the room: redact
- return False
- return True
- # Lets check to see if all the events have a history visibility
- # of "shared" or "world_readable". If thats the case then we don't
- # need to check membership (as we know the server is in the room).
- event_to_state_ids = yield storage.state.get_state_ids_for_events(
- frozenset(e.event_id for e in events),
- state_filter=StateFilter.from_types(
- types=((EventTypes.RoomHistoryVisibility, ""),)
- ),
- )
- visibility_ids = set()
- for sids in itervalues(event_to_state_ids):
- hist = sids.get((EventTypes.RoomHistoryVisibility, ""))
- if hist:
- visibility_ids.add(hist)
- # If we failed to find any history visibility events then the default
- # is "shared" visiblity.
- if not visibility_ids:
- all_open = True
- else:
- event_map = yield storage.main.get_events(visibility_ids)
- all_open = all(
- e.content.get("history_visibility") in (None, "shared", "world_readable")
- for e in itervalues(event_map)
- )
- if not check_history_visibility_only:
- erased_senders = yield storage.main.are_users_erased((e.sender for e in events))
- else:
- # We don't want to check whether users are erased, which is equivalent
- # to no users having been erased.
- erased_senders = {}
- if all_open:
- # all the history_visibility state affecting these events is open, so
- # we don't need to filter by membership state. We *do* need to check
- # for user erasure, though.
- if erased_senders:
- to_return = []
- for e in events:
- if not is_sender_erased(e, erased_senders):
- to_return.append(e)
- elif redact:
- to_return.append(prune_event(e))
- return to_return
- # If there are no erased users then we can just return the given list
- # of events without having to copy it.
- return events
- # Ok, so we're dealing with events that have non-trivial visibility
- # rules, so we need to also get the memberships of the room.
- # first, for each event we're wanting to return, get the event_ids
- # of the history vis and membership state at those events.
- event_to_state_ids = yield storage.state.get_state_ids_for_events(
- frozenset(e.event_id for e in events),
- state_filter=StateFilter.from_types(
- types=((EventTypes.RoomHistoryVisibility, ""), (EventTypes.Member, None))
- ),
- )
- # We only want to pull out member events that correspond to the
- # server's domain.
- #
- # event_to_state_ids contains lots of duplicates, so it turns out to be
- # cheaper to build a complete event_id => (type, state_key) dict, and then
- # filter out the ones we don't want
- #
- event_id_to_state_key = {
- event_id: key
- for key_to_eid in itervalues(event_to_state_ids)
- for key, event_id in iteritems(key_to_eid)
- }
- def include(typ, state_key):
- if typ != EventTypes.Member:
- return True
- # we avoid using get_domain_from_id here for efficiency.
- idx = state_key.find(":")
- if idx == -1:
- return False
- return state_key[idx + 1 :] == server_name
- event_map = yield storage.main.get_events(
- [
- e_id
- for e_id, key in iteritems(event_id_to_state_key)
- if include(key[0], key[1])
- ]
- )
- event_to_state = {
- e_id: {
- key: event_map[inner_e_id]
- for key, inner_e_id in iteritems(key_to_eid)
- if inner_e_id in event_map
- }
- for e_id, key_to_eid in iteritems(event_to_state_ids)
- }
- to_return = []
- for e in events:
- erased = is_sender_erased(e, erased_senders)
- visible = check_event_is_visible(e, event_to_state[e.event_id])
- if visible and not erased:
- to_return.append(e)
- elif redact:
- to_return.append(prune_event(e))
- return to_return
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