diff options
| -rw-r--r-- | changelog.d/6524.misc | 2 | ||||
| -rw-r--r-- | synapse/handlers/federation.py | 78 |
2 files changed, 56 insertions, 24 deletions
diff --git a/changelog.d/6524.misc b/changelog.d/6524.misc new file mode 100644 index 0000000000..f885597426 --- /dev/null +++ b/changelog.d/6524.misc @@ -0,0 +1,2 @@ +Improve sanity-checking when receiving events over federation. + diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 31c9132ae9..ebeffbb768 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -571,7 +571,9 @@ class FederationHandler(BaseHandler): @defer.inlineCallbacks @log_function - def _get_state_for_room(self, destination, room_id, event_id, include_event_in_state): + def _get_state_for_room( + self, destination, room_id, event_id, include_event_in_state + ): """Requests all of the room state at a given event from a remote homeserver. Args: @@ -635,6 +637,10 @@ class FederationHandler(BaseHandler): room_id (str) event_ids (Iterable[str]) + If we fail to fetch any of the events, a warning will be logged, and the event + will be omitted from the result. Likewise, any events which turn out not to + be in the given room. + Returns: Deferred[dict[str, EventBase]]: A deferred resolving to a map from event_id to event @@ -643,35 +649,59 @@ class FederationHandler(BaseHandler): missing_events = set(event_ids) - fetched_events.keys() - if not missing_events: - return fetched_events + if missing_events: + logger.debug( + "Fetching unknown state/auth events %s for room %s", + missing_events, + room_id, + ) - logger.debug( - "Fetching unknown state/auth events %s for room %s", - missing_events, - event_ids, - ) + room_version = yield self.store.get_room_version(room_id) - room_version = yield self.store.get_room_version(room_id) + # XXX 20 requests at once? really? + for batch in batch_iter(missing_events, 20): + deferreds = [ + run_in_background( + self.federation_client.get_pdu, + destinations=[destination], + event_id=e_id, + room_version=room_version, + ) + for e_id in batch + ] - # XXX 20 requests at once? really? - for batch in batch_iter(missing_events, 20): - deferreds = [ - run_in_background( - self.federation_client.get_pdu, - destinations=[destination], - event_id=e_id, - room_version=room_version, + res = yield make_deferred_yieldable( + defer.DeferredList(deferreds, consumeErrors=True) ) - for e_id in batch - ] - res = yield make_deferred_yieldable( - defer.DeferredList(deferreds, consumeErrors=True) + for success, result in res: + if success and result: + fetched_events[result.event_id] = result + + # check for events which were in the wrong room. + # + # this can happen if a remote server claims that the state or + # auth_events at an event in room A are actually events in room B + + bad_events = list( + (event_id, event.room_id) + for event_id, event in fetched_events.items() + if event.room_id != room_id + ) + + for bad_event_id, bad_room_id in bad_events: + # This is a bogus situation, but since we may only discover it a long time + # after it happened, we try our best to carry on, by just omitting the + # bad events from the returned auth/state set. + logger.warning( + "Remote server %s claims event %s in room %s is an auth/state " + "event in room %s", + destination, + bad_event_id, + bad_room_id, + room_id, ) - for success, result in res: - if success and result: - fetched_events[result.event_id] = result + del fetched_events[bad_event_id] return fetched_events |