Reject make_join for empty rooms (#1439)

* Sanity-check room version on RS event input

* Update gomatrixserverlib

* Reject make_join when no room members are left

* Revert some changes from wrong branch

* Distinguish between room not existing and room being abandoned on this server

* nolint

2 files changed, 28 insertions, 0 deletions

diff --git a/roomserver/inthttp/client.go b/roomserver/inthttp/client.go
index f2510c75..3dd3edaf 100644
--- a/roomserver/inthttp/client.go
+++ b/roomserver/inthttp/client.go
@@ -38,6 +38,7 @@ const (
 	RoomserverQueryEventsByIDPath              = "/roomserver/queryEventsByID"
 	RoomserverQueryMembershipForUserPath       = "/roomserver/queryMembershipForUser"
 	RoomserverQueryMembershipsForRoomPath      = "/roomserver/queryMembershipsForRoom"
+	RoomserverQueryServerJoinedToRoomPath      = "/roomserver/queryServerJoinedToRoomPath"
 	RoomserverQueryServerAllowedToSeeEventPath = "/roomserver/queryServerAllowedToSeeEvent"
 	RoomserverQueryMissingEventsPath           = "/roomserver/queryMissingEvents"
 	RoomserverQueryStateAndAuthChainPath       = "/roomserver/queryStateAndAuthChain"
@@ -312,6 +313,19 @@ func (h *httpRoomserverInternalAPI) QueryMembershipsForRoom(
 	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
 }
 
+// QueryMembershipsForRoom implements RoomserverQueryAPI
+func (h *httpRoomserverInternalAPI) QueryServerJoinedToRoom(
+	ctx context.Context,
+	request *api.QueryServerJoinedToRoomRequest,
+	response *api.QueryServerJoinedToRoomResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "QueryServerJoinedToRoom")
+	defer span.Finish()
+
+	apiURL := h.roomserverURL + RoomserverQueryServerJoinedToRoomPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
+
 // QueryServerAllowedToSeeEvent implements RoomserverQueryAPI
 func (h *httpRoomserverInternalAPI) QueryServerAllowedToSeeEvent(
 	ctx context.Context,
diff --git a/roomserver/inthttp/server.go b/roomserver/inthttp/server.go
index 8ffa9cf9..c7e541dd 100644
--- a/roomserver/inthttp/server.go
+++ b/roomserver/inthttp/server.go
@@ -168,6 +168,20 @@ func AddRoutes(r api.RoomserverInternalAPI, internalAPIMux *mux.Router) {
 		}),
 	)
 	internalAPIMux.Handle(
+		RoomserverQueryServerJoinedToRoomPath,
+		httputil.MakeInternalAPI("queryServerJoinedToRoom", func(req *http.Request) util.JSONResponse {
+			var request api.QueryServerJoinedToRoomRequest
+			var response api.QueryServerJoinedToRoomResponse
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.ErrorResponse(err)
+			}
+			if err := r.QueryServerJoinedToRoom(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
+	internalAPIMux.Handle(
 		RoomserverQueryServerAllowedToSeeEventPath,
 		httputil.MakeInternalAPI("queryServerAllowedToSeeEvent", func(req *http.Request) util.JSONResponse {
 			var request api.QueryServerAllowedToSeeEventRequest