Make sure that we accept join events from any server, rather than just the
origin server, to make the federation join dance work correctly.
(Fixes#1893).
Fix a bug in ``logcontext.preserve_fn`` which made it leak context into the
reactor, and add a test for it.
Also, get rid of ``logcontext.reset_context_after_deferred``, which tried to do
the same thing but had its own, different, set of bugs.
A few non-functional changes:
* A bunch of docstrings to document types
* Split `EventsStore._persist_events_txn` up a bit. Hopefully it's a bit more
readable.
* Rephrase `EventFederationStore._update_min_depth_for_room_txn` to avoid
mind-bending conditional.
* Rephrase rejected/outlier conditional in `_update_outliers_txn` to avoid
mind-bending conditional.
This just takes the existing `room_queues` logic and moves it out to
`on_receive_pdu` instead of `_process_received_pdu`, which ensures that we
don't start trying to fetch prev_events and whathaveyou until the join has
completed.
Unfortunately this significantly increases the size of the already-rather-big
FederationHandler, but the code fits more naturally here, and it paves the way
for the tighter integration that I need between handling incoming PDUs and
doing the join dance.
Other than renaming the existing `FederationHandler.on_receive_pdu` to
`_process_received_pdu` to make way for it, this just consists of the move, and
replacing `self.handler` with `self` and `self` with `self.replication_layer`.
When a server sends a third party invite another server may be the one
that the inviting user registers with. In this case it is that remote
server that will issue an actual invitation, and wants to do it "in the
name of" the original invitee. However, the new proper invite will not
be signed by the original server, and thus other servers would reject
the invite if it was seen as coming from the original user.
To fix this, a special case has been added to the auth rules whereby
another server can send an invite "in the name of" another server's
user, so long as that user had previously issued a third party invite
that is now being accepted.
