Make separate API call for room membership

federationapi/routing/send.go

@@ -573,6 +573,23 @@ func (t *txnReq) processEvent(ctx context.Context, e *gomatrixserverlib.Event) e
 	logger := util.GetLogger(ctx).WithField("event_id", e.EventID()).WithField("room_id", e.RoomID())
 	t.work = "" // reset from previous event
 
+	// Ask the roomserver if we know about the room and/or if we're joined
+	// to it. If we aren't then we won't bother processing the event.
+	joinedReq := api.QueryServerJoinedToRoomRequest{
+		RoomID: e.RoomID(),
+	}
+	var joinedRes api.QueryServerJoinedToRoomResponse
+	if err := t.rsAPI.QueryServerJoinedToRoom(ctx, &joinedReq, &joinedRes); err != nil {
+		return fmt.Errorf("t.rsAPI.QueryServerJoinedToRoom: %w", err)
+	}
+
+	if !joinedRes.RoomExists || !joinedRes.IsInRoom {
+		// We don't believe we're a member of this room, therefore there's
+		// no point in wasting work trying to figure out what to do with
+		// missing auth or prev events. Drop the event.
+		return roomNotFoundError{e.RoomID()}
+	}
+
 	// Work out if the roomserver knows everything it needs to know to auth
 	// the event. This includes the prev_events and auth_events.
 	// NOTE! This is going to include prev_events that have an empty state
@@ -589,23 +606,6 @@ func (t *txnReq) processEvent(ctx context.Context, e *gomatrixserverlib.Event) e
 		return fmt.Errorf("t.rsAPI.QueryMissingAuthPrevEvents: %w", err)
 	}
 
-	if !stateResp.RoomExists {
-		// TODO: When synapse receives a message for a room it is not in it
-		// asks the remote server for the state of the room so that it can
-		// check if the remote server knows of a join "m.room.member" event
-		// that this server is unaware of.
-		// However generally speaking we should reject events for rooms we
-		// aren't a member of.
-		return roomNotFoundError{e.RoomID()}
-	}
-
-	if !stateResp.RoomJoined {
-		// We don't believe we're a member of this room anymore, therefore
-		// there's no point in wasting work trying to figure out what to do
-		// with missing auth or prev events. Silently drop the event.
-		return nil
-	}
-
 	// Prepare a map of all the events we already had before this point, so
 	// that we don't send them to the roomserver again.
 	for _, eventID := range append(e.AuthEventIDs(), e.PrevEventIDs()...) {

federationapi/routing/send_test.go

@@ -142,7 +142,6 @@ func (t *testRoomserverAPI) QueryMissingAuthPrevEvents(
 	response.RoomVersion = testRoomVersion
 	res := t.queryMissingAuthPrevEvents(request)
 	response.RoomExists = res.RoomExists
-	response.RoomJoined = true
 	response.MissingAuthEventIDs = res.MissingAuthEventIDs
 	response.MissingPrevEventIDs = res.MissingPrevEventIDs
 	return nil
@@ -191,7 +190,9 @@ func (t *testRoomserverAPI) QueryServerJoinedToRoom(
 	request *api.QueryServerJoinedToRoomRequest,
 	response *api.QueryServerJoinedToRoomResponse,
 ) error {
-	return fmt.Errorf("not implemented")
+	response.RoomExists = true
+	response.IsInRoom = true
+	return nil
 }
 
 // Query whether a server is allowed to see an event

roomserver/api/query.go

@@ -96,8 +96,6 @@ type QueryMissingAuthPrevEventsResponse struct {
 	// Does the room exist on this roomserver?
 	// If the room doesn't exist all other fields will be empty.
 	RoomExists bool `json:"room_exists"`
-	// Are we joined to this room locally?
-	RoomJoined bool `json:"room_joined"`
 	// The room version of the room.
 	RoomVersion gomatrixserverlib.RoomVersion `json:"room_version"`
 	// The event IDs of the auth events that we don't know locally.
@@ -172,7 +170,8 @@ type QueryMembershipsForRoomResponse struct {
 
 // QueryServerJoinedToRoomRequest is a request to QueryServerJoinedToRoom
 type QueryServerJoinedToRoomRequest struct {
-	// Server name of the server to find
+	// Server name of the server to find. If not specified, we will
+	// default to checking if the local server is joined.
 	ServerName gomatrixserverlib.ServerName `json:"server_name"`
 	// ID of the room to see if we are still joined to
 	RoomID string `json:"room_id"`

roomserver/internal/query/query.go

@@ -142,14 +142,6 @@ func (r *Queryer) QueryMissingAuthPrevEvents(
 	response.RoomExists = !info.IsStub
 	response.RoomVersion = info.RoomVersion
 
-	if response.RoomExists {
-		joined, err := r.DB.GetLocalServerInRoom(ctx, info.RoomNID)
-		if err != nil {
-			return fmt.Errorf("r.DB.GetLocalServerInRoom: %w", err)
-		}
-		response.RoomJoined = joined
-	}
-
 	for _, authEventID := range request.AuthEventIDs {
 		if nids, err := r.DB.EventNIDs(ctx, []string{authEventID}); err != nil || len(nids) == 0 {
 			response.MissingAuthEventIDs = append(response.MissingAuthEventIDs, authEventID)
@@ -337,7 +329,7 @@ func (r *Queryer) QueryServerJoinedToRoom(
 	}
 	response.RoomExists = true
 
-	if request.ServerName == r.ServerName {
+	if request.ServerName == r.ServerName || request.ServerName == "" {
 		var joined bool
 		joined, err = r.DB.GetLocalServerInRoom(ctx, info.RoomNID)
 		if err != nil {