Don't query auth if the only difference is events that were rejected due to auth.

synapse/handlers/federation.py

@@ -791,12 +791,12 @@ class FederationHandler(BaseHandler):
     @log_function
     def do_auth(self, origin, event, context, auth_events):
         # Check if we have all the auth events.
-        res = yield self.store.have_events(
+        have_events = yield self.store.have_events(
             [e_id for e_id, _ in event.auth_events]
         )
 
         event_auth_events = set(e_id for e_id, _ in event.auth_events)
-        seen_events = set(res.keys())
+        seen_events = set(have_events.keys())
 
         missing_auth = event_auth_events - seen_events
 
@@ -839,6 +839,11 @@ class FederationHandler(BaseHandler):
                             auth_events[(e.type, e.state_key)] = e
                     except AuthError:
                         pass
+
+                have_events = yield self.store.have_events(
+                    [e_id for e_id, _ in event.auth_events]
+                )
+                seen_events = set(have_events.keys())
             except:
                 # FIXME:
                 logger.exception("Failed to get auth chain")
@@ -852,6 +857,16 @@ class FederationHandler(BaseHandler):
             # Do auth conflict res.
             logger.debug("Different auth: %s", different_auth)
 
+            # Only do auth resolution if we have something new to say.
+            # We can't rove an auth failure.
+            do_resolution = False
+            for e_id in different_auth:
+                if e_id in have_events:
+                    if have_events[e_id] != RejectedReason.AUTH_ERROR:
+                        do_resolution = True
+                        break
+
+            if do_resolution:
                 # 1. Get what we think is the auth chain.
                 auth_ids = self.auth.compute_auth_events(
                     event, context.current_state
@@ -882,7 +897,8 @@ class FederationHandler(BaseHandler):
                         try:
                             auth_ids = [e_id for e_id, _ in ev.auth_events]
                             auth = {
-                            (e.type, e.state_key): e for e in result["auth_chain"]
+                                (e.type, e.state_key): e
+                                for e in result["auth_chain"]
                                 if e.event_id in auth_ids
                             }
                             ev.internal_metadata.outlier = True
@@ -1028,9 +1044,9 @@ class FederationHandler(BaseHandler):
         for e in base_remote_rejected:
             reason = yield self.store.get_rejection_reason(e.event_id)
             if reason is None:
-                # FIXME: ERRR?!
-                logger.warn("Could not find reason for %s", e.event_id)
-                raise RuntimeError("Could not find reason for %s" % e.event_id)
+                # TODO: e is not in the current state, so we should
+                # construct some proof of that.
+                continue
 
             reason_map[e.event_id] = reason