Refactor SendMembership - make ban test pass (#1160)

* Refactor SendMembership - make ban test pass

* Only check invite auth events for local invites

roomserver/internal/perform_invite.go

@@ -55,6 +55,7 @@ func (r *RoomserverInternalAPI) performInvite(ctx context.Context,
 	return nil
 }
 
+// nolint:gocyclo
 func (r *RoomserverInternalAPI) processInviteEvent(
 	ctx context.Context,
 	ow *RoomserverInternalAPI,
@@ -135,6 +136,25 @@ func (r *RoomserverInternalAPI) processInviteEvent(
 	}
 
 	event := input.Event.Unwrap()
+
+	// check that the user is allowed to do this. We can only do this check if it is
+	// a local invite as we have the auth events, else we have to take it on trust.
+	if loopback != nil {
+		_, err = checkAuthEvents(ctx, r.DB, input.Event, input.Event.AuthEventIDs())
+		if err != nil {
+			log.WithError(err).WithField("event_id", event.EventID()).WithField("auth_event_ids", event.AuthEventIDs()).Error(
+				"processInviteEvent.checkAuthEvents failed for event",
+			)
+			if _, ok := err.(*gomatrixserverlib.NotAllowed); ok {
+				return nil, &api.PerformError{
+					Msg:  err.Error(),
+					Code: api.PerformErrorNotAllowed,
+				}
+			}
+			return nil, err
+		}
+	}
+
 	if len(input.InviteRoomState) > 0 {
 		// If we were supplied with some invite room state already (which is
 		// most likely to be if the event came in over federation) then use

roomserver/internal/query.go

@@ -225,13 +225,18 @@ func (r *RoomserverInternalAPI) QueryMembershipForUser(
 	}
 
 	response.IsInRoom = stillInRoom
-	eventIDMap, err := r.DB.EventIDs(ctx, []types.EventNID{membershipEventNID})
+
+	evs, err := r.DB.Events(ctx, []types.EventNID{membershipEventNID})
 	if err != nil {
 		return err
 	}
+	if len(evs) != 1 {
+		return fmt.Errorf("failed to load membership event for event NID %d", membershipEventNID)
+	}
 
-	response.EventID = eventIDMap[membershipEventNID]
-	return nil
+	response.EventID = evs[0].EventID()
+	response.Membership, err = evs[0].Membership()
+	return err
 }
 
 // QueryMembershipsForRoom implements api.RoomserverInternalAPI