Return sooner when joining room over federation

clientapi/routing/joinroom.go

@@ -332,6 +332,7 @@ func (r joinRoomReq) joinRoomUsingServer(roomID string, server gomatrixserverlib
 		RoomID:     roomID,
 		UserID:     r.userID,
 		ServerName: server,
+		Content:    r.content,
 	}
 	fedJoinRes := federationSenderAPI.PerformJoinResponse{}
 	if err := r.fsAPI.PerformJoin(r.req.Context(), &fedJoinReq, &fedJoinRes); err != nil {

federationsender/query/perform.go

@@ -9,6 +9,7 @@ import (
 	"github.com/matrix-org/dendrite/federationsender/query/perform"
 	"github.com/matrix-org/dendrite/roomserver/version"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/sirupsen/logrus"
 )
 
 // PerformJoinRequest implements api.FederationSenderInternalAPI
@@ -87,12 +88,28 @@ func (r *FederationSenderInternalAPI) PerformJoin(
 		return fmt.Errorf("r.federation.SendJoin: %w", err)
 	}
 
+	// At this point, if the above /send_join didn't return an error,
+	// then the resident servers think we're in the room. We need
+	// to verify the state and auth chain and notify the roomserver
+	// but this can take an awful long time in big rooms and there's
+	// every possibility that client may give up waiting on this CS
+	// API request long before that. Therefore for now, until we
+	// have a /confirm_join step, just let the client think that the
+	// request succeeded and work it out in our own time. There's
+	// every possibility this might fail, and if so, the room will
+	// just never appear in the sync stream. That's about the best
+	// we can do for now.
+	go func() {
+		// Don't expire with the original request context.
+		ctx := context.Background()
+
 		// Check that the send_join response was valid.
 		joinCtx := perform.JoinContext(r.federation, r.keyRing)
 		if err = joinCtx.CheckSendJoinResponse(
 			ctx, event, request.ServerName, respMakeJoin, respSendJoin,
 		); err != nil {
-		return fmt.Errorf("perform.JoinRequest.CheckSendJoinResponse: %w", err)
+			logrus.WithError(err).Errorf("perform.JoinRequest.CheckSendJoinResponse failed")
+			return
 		}
 
 		// If we successfully performed a send_join above then the other
@@ -103,8 +120,10 @@ func (r *FederationSenderInternalAPI) PerformJoin(
 			respSendJoin.ToRespState(),
 			event.Headered(respMakeJoin.RoomVersion),
 		); err != nil {
-		return fmt.Errorf("r.producer.SendEventWithState: %w", err)
+			logrus.WithError(err).Errorf("r.producer.SendEventWithState failed")
+			return
 		}
+	}()
 
 	// Everything went to plan.
 	return nil