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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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