Fix rejecting invites over federation

changelog.d/12409.misc

@@ -0,0 +1 @@
+Avoid trying to calculate the state at outlier events.

synapse/handlers/sync.py

@@ -1850,6 +1850,7 @@ async def _get_rooms_changed(
  full_state=False,
  since_token=since_token,
  upto_token=leave_token,
+ out_of_band=leave_event.internal_metadata.is_out_of_band_membership(),
  )
  )
 
@@ -2116,33 +2117,41 @@ async def _generate_room_entry(
  ):
  return
 
- state = await self.compute_state_delta(
- room_id,
- batch,
- sync_config,
- since_token,
- now_token,
- full_state=full_state,
- )
+ if not room_builder.out_of_band:
+ state = await self.compute_state_delta(
+ room_id,
+ batch,
+ sync_config,
+ since_token,
+ now_token,
+ full_state=full_state,
+ )
+ else:
+ # An out of band room won't have any state changes.
+ state = {}
 
  summary: Optional[JsonDict] = {}
 
  # we include a summary in room responses when we're lazy loading
  # members (as the client otherwise doesn't have enough info to form
  # the name itself).
- if sync_config.filter_collection.lazy_load_members() and (
- # we recalculate the summary:
- # if there are membership changes in the timeline, or
- # if membership has changed during a gappy sync, or
- # if this is an initial sync.
- any(ev.type == EventTypes.Member for ev in batch.events)
- or (
- # XXX: this may include false positives in the form of LL
- # members which have snuck into state
- batch.limited
- and any(t == EventTypes.Member for (t, k) in state)
+ if (
+ not room_builder.out_of_band
+ and sync_config.filter_collection.lazy_load_members()
+ and (
+ # we recalculate the summary:
+ # if there are membership changes in the timeline, or
+ # if membership has changed during a gappy sync, or
+ # if this is an initial sync.
+ any(ev.type == EventTypes.Member for ev in batch.events)
+ or (
+ # XXX: this may include false positives in the form of LL
+ # members which have snuck into state
+ batch.limited
+ and any(t == EventTypes.Member for (t, k) in state)
+ )
+ or since_token is None
  )
- or since_token is None
  ):
  summary = await self.compute_summary(
  room_id, sync_config, batch, state, now_token
@@ -2386,6 +2395,8 @@ class RoomSyncResultBuilder:
  full_state: Whether the full state should be sent in result
  since_token: Earliest point to return events from, or None
  upto_token: Latest point to return events from.
+ out_of_band: whether the events in the room are "out of band" events
+ and the server isn't in the room.
  """
 
  room_id: str
@@ -2395,3 +2406,5 @@ class RoomSyncResultBuilder:
  full_state: bool
  since_token: Optional[StreamToken]
  upto_token: StreamToken
+
+ out_of_band: bool = False