diff options
| -rw-r--r-- | synapse/federation/federation_server.py | 25 | ||||
| -rw-r--r-- | synapse/handlers/federation.py | 15 |
2 files changed, 35 insertions, 5 deletions
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py index e4ce037acf..682721cec7 100644 --- a/synapse/federation/federation_server.py +++ b/synapse/federation/federation_server.py @@ -1,5 +1,6 @@ # -*- coding: utf-8 -*- # Copyright 2015, 2016 OpenMarket Ltd +# Copyright 2018 New Vector Ltd # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. @@ -494,13 +495,33 @@ class FederationServer(FederationBase): def _handle_received_pdu(self, origin, pdu): """ Process a PDU received in a federation /send/ transaction. + If the event is invalid, then this method throws a FederationError. + (The error will then be logged and sent back to the sender (which + probably won't do anything with it), and other events in the + transaction will be processed as normal). + + It is likely that we'll then receive other events which refer to + this rejected_event in their prev_events, etc. When that happens, + we'll attempt to fetch the rejected event again, which will presumably + fail, so those second-generation events will also get rejected. + + Eventually, we get to the point where there are more than 10 events + between any new events and the original rejected event. Since we + only try to backfill 10 events deep on received pdu, we then accept the + new event, possibly introducing a discontinuity in the DAG, with new + forward extremities, so normal service is approximately returned, + until we try to backfill across the discontinuity. + Args: origin (str): server which sent the pdu pdu (FrozenEvent): received pdu Returns (Deferred): completes with None - Raises: FederationError if the signatures / hash do not match - """ + + Raises: FederationError if the signatures / hash do not match, or + if the event was unacceptable for any other reason (eg, too large, + too many prev_events, couldn't find the prev_events) + """ # check that it's actually being sent from a valid destination to # workaround bug #1753 in 0.18.5 and 0.18.6 if origin != get_domain_from_id(pdu.event_id): diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index 310db3fb46..1296e22af6 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -542,9 +542,16 @@ class FederationHandler(BaseHandler): def backfill(self, dest, room_id, limit, extremities): """ Trigger a backfill request to `dest` for the given `room_id` - This will attempt to get more events from the remote. This may return - be successfull and still return no events if the other side has no new - events to offer. + This will attempt to get more events from the remote. If the other side + has no new events to offer, this will return an empty list. + + As the events are received, we check their signatures, and also do some + sanity-checking on them. If any of the backfilled events are invalid, + this method throws a SynapseError. + + TODO: make this more useful to distinguish failures of the remote + server from invalid events (there is probably no point in trying to + re-fetch invalid events from every other HS in the room.) """ if dest == self.server_name: raise SynapseError(400, "Can't backfill from self.") @@ -556,6 +563,8 @@ class FederationHandler(BaseHandler): extremities=extremities, ) + # do some sanity-checking of the received events, before we go and + # do state resolution across 1000 events. for ev in events: self._sanity_check_event(ev) |