Exclude rejected state events when calculating state at backwards extrems (#6527)

This fixes a weird bug where, if you were determined enough, you could end up with a rejected event forming part of the state at a backwards-extremity. Authing that backwards extrem would then lead to us trying to pull the rejected event from the db (with allow_rejected=False), which would fail with a 404.
This commit is contained in:
Richard van der Hoff 2019-12-16 13:14:37 +00:00 committed by Richard van der Hoff
parent ff773ff724
commit bbb75ff6ee
2 changed files with 2 additions and 1 deletions

1
changelog.d/6527.bugfix Normal file
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@ -0,0 +1 @@
Fix a bug which could cause the federation server to incorrectly return errors when handling certain obscure event graphs.

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@ -606,7 +606,7 @@ class FederationHandler(BaseHandler):
remote_event = event_map.get(event_id)
if not remote_event:
raise Exception("Unable to get missing prev_event %s" % (event_id,))
if remote_event.is_state():
if remote_event.is_state() and remote_event.rejected_reason is None:
remote_state.append(remote_event)
auth_chain = [event_map[e_id] for e_id in auth_event_ids if e_id in event_map]