Fixes a bug where rejected events were persisted with the wrong state group.
Also fixes an occasional internal-server-error when receiving events over
federation which are rejected and (possibly because they are
backwards-extremities) have no prev_group.
Fixes#6289.
* Raise an exception if accessing state for rejected events
Add some sanity checks on accessing state_group etc for
rejected events.
* Skip calculating push actions for rejected events
It didn't actually cause any bugs, because rejected events get filtered out at
various later points, but there's not point in trying to calculate the push
actions for a rejected event.
The intention here is to make it clearer which fields we can expect to be
populated when: notably, that the _event_type etc aren't used for the
synchronous impl of EventContext.
While this is not documented in the spec (but should be), Riot (and other clients) revoke 3PID invites by sending a m.room.third_party_invite event with an empty ({}) content to the room's state.
When the invited 3PID gets associated with a MXID, the identity server (which doesn't know about revocations) sends down to the MXID's homeserver all of the undelivered invites it has for this 3PID. The homeserver then tries to talk to the inviting homeserver in order to exchange these invite for m.room.member events.
When one of the invite is revoked, the inviting homeserver responds with a 500 error because it tries to extract a 'display_name' property from the content, which is empty. This might cause the invited server to consider that the server is down and not try to exchange other, valid invites (or at least delay it).
This fix handles the case of revoked invites by avoiding trying to fetch a 'display_name' from the original invite's content, and letting the m.room.member event fail the auth rules (because, since the original invite's content is empty, it doesn't have public keys), which results in sending a 403 with the correct error message to the invited server.
Another small fixup noticed during work on a larger PR. The `origin` field of `add_display_name_to_third_party_invite` is not used and likely was just carried over from the `on_PUT` method of `FederationThirdPartyInviteExchangeServlet` which, like all other servlets, provides an `origin` argument.
Since it's not used anywhere in the handler function though, we should remove it from the function arguments.
Python will return a tuple whether there are parentheses around the returned values or not.
I'm just sick of my editor complaining about this all over the place :)
I had to add quite a lot of logging to diagnose a problem with 3pid
invites - we only logged the one failure which isn't all that
informative.
NB. I'm not convinced the logic of this loop is right: I think it
should just accept a single valid signature from a trusted source
rather than fail if *any* signature is invalid. Also it should
probably not skip the rest of middle loop if a check fails? However,
I'm deliberately not changing the logic here.
Fixes that when a user exchanges a 3PID invite for a proper invite over
federation it does not include the `invite_room_state` key.
This was due to synapse incorrectly sending out two invite requests.
