Fix backfill auth events

synapse/handlers/federation.py

@@ -335,32 +335,59 @@ class FederationHandler(BaseHandler):
             state_events.update({s.event_id: s for s in state})
             events_to_state[e_id] = state
 
+        required_auth = set(
+            a_id
+            for event in events + state_events.values() + auth_events.values()
+            for a_id, _ in event.auth_events
+        )
+        auth_events.update({
+            e_id: event_map[e_id] for e_id in required_auth if e_id in event_map
+        })
+        missing_auth = required_auth - set(auth_events)
+        failed_to_fetch = set()
+
+        # Try and fetch any missing auth events from both DB and remote servers.
+        # We repeatedly do this until we stop finding new auth events.
+        while missing_auth - failed_to_fetch:
+            logger.info("Missing auth for backfill: %r", missing_auth)
+            ret_events = yield self.store.get_events(missing_auth - failed_to_fetch)
+            auth_events.update(ret_events)
+
+            required_auth.update(
+                a_id for event in ret_events.values() for a_id, _ in event.auth_events
+            )
+            missing_auth = required_auth - set(auth_events)
+
+            if missing_auth - failed_to_fetch:
+                logger.info(
+                    "Fetching missing auth for backfill: %r",
+                    missing_auth - failed_to_fetch
+                )
+
+                results = yield defer.gatherResults(
+                    [
+                        self.replication_layer.get_pdu(
+                            [dest],
+                            event_id,
+                            outlier=True,
+                            timeout=10000,
+                        )
+                        for event_id in missing_auth - failed_to_fetch
+                    ],
+                    consumeErrors=True
+                ).addErrback(unwrapFirstError)
+                auth_events.update({a.event_id: a for a in results})
+                required_auth.update(
+                    a_id for event in results for a_id, _ in event.auth_events
+                )
+                missing_auth = required_auth - set(auth_events)
+
+                failed_to_fetch = missing_auth - set(auth_events)
+
         seen_events = yield self.store.have_events(
             set(auth_events.keys()) | set(state_events.keys())
         )
 
-        all_events = events + state_events.values() + auth_events.values()
-        required_auth = set(
-            a_id for event in all_events for a_id, _ in event.auth_events
-        )
-
-        missing_auth = required_auth - set(auth_events)
-        if missing_auth:
-            logger.info("Missing auth for backfill: %r", missing_auth)
-            results = yield defer.gatherResults(
-                [
-                    self.replication_layer.get_pdu(
-                        [dest],
-                        event_id,
-                        outlier=True,
-                        timeout=10000,
-                    )
-                    for event_id in missing_auth
-                ],
-                consumeErrors=True
-            ).addErrback(unwrapFirstError)
-            auth_events.update({a.event_id: a for a in results})
-
         ev_infos = []
         for a in auth_events.values():
             if a.event_id in seen_events:
@@ -372,6 +399,7 @@ class FederationHandler(BaseHandler):
                     (auth_events[a_id].type, auth_events[a_id].state_key):
                     auth_events[a_id]
                     for a_id, _ in a.auth_events
+                    if a_id in auth_events
                 }
             })
 
@@ -383,6 +411,7 @@ class FederationHandler(BaseHandler):
                     (auth_events[a_id].type, auth_events[a_id].state_key):
                     auth_events[a_id]
                     for a_id, _ in event_map[e_id].auth_events
+                    if a_id in auth_events
                 }
             })