diff options
| -rw-r--r-- | changelog.d/10987.misc | 1 | ||||
| -rw-r--r-- | synapse/handlers/federation_event.py | 26 |
2 files changed, 27 insertions, 0 deletions
diff --git a/changelog.d/10987.misc b/changelog.d/10987.misc new file mode 100644 index 0000000000..9a765435db --- /dev/null +++ b/changelog.d/10987.misc @@ -0,0 +1 @@ +Clean up some of the federation event authentication code for clarity. diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py index 5938654338..aa20d75550 100644 --- a/synapse/handlers/federation_event.py +++ b/synapse/handlers/federation_event.py @@ -1476,6 +1476,11 @@ class FederationEventHandler: logger.debug("Events %s are in the store", have_events) missing_auth.difference_update(have_events) + # missing_auth is now the set of event_ids which: + # a. are listed in event.auth_events, *and* + # b. are *not* part of our calculated auth events based on room state, *and* + # c. are *not* yet in our database. + if missing_auth: # If we don't have all the auth events, we need to get them. logger.info("auth_events contains unknown events: %s", missing_auth) @@ -1497,10 +1502,31 @@ class FederationEventHandler: } ) + # auth_events now contains + # 1. our *calculated* auth events based on the room state, plus: + # 2. any events which: + # a. are listed in `event.auth_events`, *and* + # b. are not part of our calculated auth events, *and* + # c. were not in our database before the call to /event_auth + # d. have since been added to our database (most likely by /event_auth). + different_auth = event_auth_events.difference( e.event_id for e in auth_events.values() ) + # different_auth is the set of events which *are* in `event.auth_events`, but + # which are *not* in `auth_events`. Comparing with (2.) above, this means + # exclusively the set of `event.auth_events` which we already had in our + # database before any call to /event_auth. + # + # I'm reasonably sure that the fact that events returned by /event_auth are + # blindly added to auth_events (and hence excluded from different_auth) is a bug + # - though it's a very long-standing one (see + # https://github.com/matrix-org/synapse/commit/78015948a7febb18e000651f72f8f58830a55b93#diff-0bc92da3d703202f5b9be2d3f845e375f5b1a6bc6ba61705a8af9be1121f5e42R786 + # from Jan 2015 which seems to add it, though it actually just moves it from + # elsewhere (before that, it gets lost in a mess of huge "various bug fixes" + # PRs). + if not different_auth: return context, auth_events |