Refactor invites to be synchronous

clientapi/routing/createroom.go

@@ -371,7 +371,10 @@ func createRoom(
 	}
 
 	// If this is a direct message then we should invite the participants.
+	fmt.Println("INVITEES:")
 	for _, invitee := range r.Invite {
+		fmt.Println("*", invitee)
+
 		// Build the invite event.
 		inviteEvent, err := buildMembershipEvent(
 			req.Context(), invitee, "", accountDB, device, gomatrixserverlib.Invite,
@@ -386,8 +389,8 @@ func createRoom(
 		var strippedState []gomatrixserverlib.InviteV2StrippedState
 		for _, event := range candidates {
 			switch event.Type() {
-			// TODO: case gomatrixserverlib.MRoomEncryption:
+			case "m.room.encryption": // TODO: move this to gmsl
-			//	fallthrough
+				fallthrough
 			case gomatrixserverlib.MRoomMember:
 				fallthrough
 			case gomatrixserverlib.MRoomJoinRules:
@@ -398,15 +401,15 @@ func createRoom(
 			}
 		}
 		// Send the invite event to the roomserver.
-		if perr := roomserverAPI.SendInvite(
+		if err := roomserverAPI.SendInvite(
 			req.Context(), rsAPI,
 			inviteEvent.Headered(roomVersion),
 			strippedState,         // invite room state
 			cfg.Matrix.ServerName, // send as server
 			nil,                   // transaction ID
-		); perr != nil {
+		); err != nil {
-			util.GetLogger(req.Context()).WithError(perr).Error("SendInvite failed")
+			util.GetLogger(req.Context()).WithError(err).Error("SendInvite failed")
-			return perr.JSONResponse()
+			return jsonerror.InternalServerError()
 		}
 	}
 

clientapi/routing/membership.go

@@ -26,6 +26,7 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/clientapi/threepid"
 	currentstateAPI "github.com/matrix-org/dendrite/currentstateserver/api"
+	federationSenderAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/config"
 	"github.com/matrix-org/dendrite/internal/eventutil"
 	"github.com/matrix-org/dendrite/roomserver/api"
@@ -172,8 +173,9 @@ func SendInvite(
 	req *http.Request, accountDB accounts.Database, device *userapi.Device,
 	roomID string, cfg *config.ClientAPI,
 	rsAPI roomserverAPI.RoomserverInternalAPI, asAPI appserviceAPI.AppServiceQueryAPI,
+	fsAPI federationSenderAPI.FederationSenderInternalAPI,
 ) util.JSONResponse {
-	body, evTime, roomVer, reqErr := extractRequestData(req, roomID, rsAPI)
+	body, evTime, _, reqErr := extractRequestData(req, roomID, rsAPI)
 	if reqErr != nil {
 		return *reqErr
 	}
@@ -214,16 +216,16 @@ func SendInvite(
 		return jsonerror.InternalServerError()
 	}
 
-	perr := roomserverAPI.SendInvite(
+	err = roomserverAPI.SendInvite(
 		req.Context(), rsAPI,
-		event.Event.Headered(roomVer),
+		*event,
 		nil, // ask the roomserver to draw up invite room state for us
 		cfg.Matrix.ServerName,
 		nil,
 	)
-	if perr != nil {
+	if err != nil {
-		util.GetLogger(req.Context()).WithError(perr).Error("producer.SendInvite failed")
+		util.GetLogger(req.Context()).WithError(err).Error("roomserverAPI.SendInvite failed")
-		return perr.JSONResponse()
+		return jsonerror.InternalServerError()
 	}
 	return util.JSONResponse{
 		Code: http.StatusOK,

clientapi/routing/routing.go

@@ -142,7 +142,7 @@ func Setup(
 			if err != nil {
 				return util.ErrorResponse(err)
 			}
-			return SendInvite(req, accountDB, device, vars["roomID"], cfg, rsAPI, asAPI)
+			return SendInvite(req, accountDB, device, vars["roomID"], cfg, rsAPI, asAPI, federationSender)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 	r0mux.Handle("/rooms/{roomID}/kick",

federationapi/routing/invite.go

@@ -143,11 +143,11 @@ func processInvite(
 	)
 
 	// Add the invite event to the roomserver.
-	if perr := api.SendInvite(
+	if err := api.SendInvite(
 		ctx, rsAPI, signedEvent.Headered(roomVer), strippedState, event.Origin(), nil,
-	); perr != nil {
+	); err != nil {
 		util.GetLogger(ctx).WithError(err).Error("producer.SendInvite failed")
-		return perr.JSONResponse()
+		return jsonerror.InternalServerError()
 	}
 
 	// Return the signed event to the originating server, it should then tell

federationapi/routing/send_test.go

@@ -102,7 +102,8 @@ func (t *testRoomserverAPI) PerformInvite(
 	ctx context.Context,
 	req *api.PerformInviteRequest,
 	res *api.PerformInviteResponse,
-) {
+) error {
+	return nil
 }
 
 func (t *testRoomserverAPI) PerformJoin(

federationsender/api/api.go

@@ -36,6 +36,12 @@ type FederationSenderInternalAPI interface {
 		request *PerformLeaveRequest,
 		response *PerformLeaveResponse,
 	) error
+	// Handle sending an invite to a remote server.
+	PerformInvite(
+		ctx context.Context,
+		request *PerformInviteRequest,
+		response *PerformInviteResponse,
+	) error
 	// Notifies the federation sender that these servers may be online and to retry sending messages.
 	PerformServersAlive(
 		ctx context.Context,
@@ -81,6 +87,16 @@ type PerformLeaveRequest struct {
 type PerformLeaveResponse struct {
 }
 
+type PerformInviteRequest struct {
+	RoomVersion     gomatrixserverlib.RoomVersion             `json:"room_version"`
+	Event           gomatrixserverlib.HeaderedEvent           `json:"event"`
+	InviteRoomState []gomatrixserverlib.InviteV2StrippedState `json:"invite_room_state"`
+}
+
+type PerformInviteResponse struct {
+	SignedEvent gomatrixserverlib.HeaderedEvent `json:"signed_event"`
+}
+
 type PerformServersAliveRequest struct {
 	Servers []gomatrixserverlib.ServerName
 }

federationsender/consumers/roomserver.go

@@ -28,7 +28,6 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
 	log "github.com/sirupsen/logrus"
-	"github.com/tidwall/gjson"
 )
 
 // OutputRoomEventConsumer consumes events that originated in the room server.
@@ -97,22 +96,6 @@ func (s *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
 			}).Panicf("roomserver output log: write room event failure")
 			return nil
 		}
-	case api.OutputTypeNewInviteEvent:
-		ev := &output.NewInviteEvent.Event
-		log.WithFields(log.Fields{
-			"event_id":  ev.EventID(),
-			"room_id":   ev.RoomID(),
-			"state_key": ev.StateKey(),
-		}).Info("received invite event from roomserver")
-
-		if err := s.processInvite(*output.NewInviteEvent); err != nil {
-			// panic rather than continue with an inconsistent database
-			log.WithFields(log.Fields{
-				"event":      string(ev.JSON()),
-				log.ErrorKey: err,
-			}).Panicf("roomserver output log: write invite event failure")
-			return nil
-		}
 	default:
 		log.WithField("type", output.Type).Debug(
 			"roomserver output log: ignoring unknown output type",
@@ -172,51 +155,6 @@ func (s *OutputRoomEventConsumer) processMessage(ore api.OutputNewRoomEvent) err
 	)
 }
 
-// processInvite handles an invite event for sending over federation.
-func (s *OutputRoomEventConsumer) processInvite(oie api.OutputNewInviteEvent) error {
-	// Don't try to reflect and resend invites that didn't originate from us.
-	if s.cfg.Matrix.ServerName != oie.Event.Origin() {
-		return nil
-	}
-
-	// Ignore invites that don't have state keys - they are invalid.
-	if oie.Event.StateKey() == nil {
-		return fmt.Errorf("event %q doesn't have state key", oie.Event.EventID())
-	}
-
-	// Don't try to handle events that are actually destined for us.
-	stateKey := *oie.Event.StateKey()
-	_, destination, err := gomatrixserverlib.SplitID('@', stateKey)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"event_id":  oie.Event.EventID(),
-			"state_key": stateKey,
-		}).Info("failed to split destination from state key")
-		return nil
-	}
-	if s.cfg.Matrix.ServerName == destination {
-		return nil
-	}
-
-	// Try to extract the room invite state. The roomserver will have stashed
-	// this for us in invite_room_state if it didn't already exist.
-	strippedState := []gomatrixserverlib.InviteV2StrippedState{}
-	if inviteRoomState := gjson.GetBytes(oie.Event.Unsigned(), "invite_room_state"); inviteRoomState.Exists() {
-		if err = json.Unmarshal([]byte(inviteRoomState.Raw), &strippedState); err != nil {
-			log.WithError(err).Warn("failed to extract invite_room_state from event unsigned")
-		}
-	}
-
-	// Build the invite request with the info we've got.
-	inviteReq, err := gomatrixserverlib.NewInviteV2Request(&oie.Event, strippedState)
-	if err != nil {
-		return fmt.Errorf("gomatrixserverlib.NewInviteV2Request: %w", err)
-	}
-
-	// Send the event.
-	return s.queues.SendInvite(&inviteReq)
-}
-
 // joinedHostsAtEvent works out a list of matrix servers that were joined to
 // the room at the event.
 // It is important to use the state at the event for sending messages because:

federationsender/internal/perform.go

@@ -296,6 +296,48 @@ func (r *FederationSenderInternalAPI) PerformLeave(
 	)
 }
 
+// PerformLeaveRequest implements api.FederationSenderInternalAPI
+func (r *FederationSenderInternalAPI) PerformInvite(
+	ctx context.Context,
+	request *api.PerformInviteRequest,
+	response *api.PerformInviteResponse,
+) (err error) {
+	if request.Event.StateKey() == nil {
+		return errors.New("invite must be a state event")
+	}
+
+	_, destination, err := gomatrixserverlib.SplitID('@', *request.Event.StateKey())
+	if err != nil {
+		return fmt.Errorf("gomatrixserverlib.SplitID: %w", err)
+	}
+
+	logrus.WithFields(logrus.Fields{
+		"event_id":     request.Event.EventID(),
+		"user_id":      *request.Event.StateKey(),
+		"room_id":      request.Event.RoomID(),
+		"room_version": request.RoomVersion,
+		"destination":  destination,
+	}).Info("Sending invite")
+
+	inviteReq, err := gomatrixserverlib.NewInviteV2Request(&request.Event, request.InviteRoomState)
+	if err != nil {
+		return fmt.Errorf("gomatrixserverlib.NewInviteV2Request: %w", err)
+	}
+
+	inviteRes, err := r.federation.SendInviteV2(ctx, destination, inviteReq)
+	if err != nil {
+		return fmt.Errorf("r.federation.SendInviteV2: %w", err)
+	}
+
+	response.SignedEvent = inviteRes.Event.Sign(
+		string(r.cfg.Matrix.ServerName),
+		r.cfg.Matrix.KeyID,
+		r.cfg.Matrix.PrivateKey,
+	).Headered(request.RoomVersion)
+
+	return nil
+}
+
 // PerformServersAlive implements api.FederationSenderInternalAPI
 func (r *FederationSenderInternalAPI) PerformServersAlive(
 	ctx context.Context,

federationsender/inthttp/client.go

@@ -18,6 +18,7 @@ const (
 	FederationSenderPerformDirectoryLookupRequestPath = "/federationsender/performDirectoryLookup"
 	FederationSenderPerformJoinRequestPath            = "/federationsender/performJoinRequest"
 	FederationSenderPerformLeaveRequestPath           = "/federationsender/performLeaveRequest"
+	FederationSenderPerformInviteRequestPath          = "/federationsender/performInviteRequest"
 	FederationSenderPerformServersAlivePath           = "/federationsender/performServersAlive"
 	FederationSenderPerformBroadcastEDUPath           = "/federationsender/performBroadcastEDU"
 )
@@ -49,6 +50,19 @@ func (h *httpFederationSenderInternalAPI) PerformLeave(
 	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
 }
 
+// Handle sending an invite to a remote server.
+func (h *httpFederationSenderInternalAPI) PerformInvite(
+	ctx context.Context,
+	request *api.PerformInviteRequest,
+	response *api.PerformInviteResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "PerformInviteRequest")
+	defer span.Finish()
+
+	apiURL := h.federationSenderURL + FederationSenderPerformInviteRequestPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
+
 func (h *httpFederationSenderInternalAPI) PerformServersAlive(
 	ctx context.Context,
 	request *api.PerformServersAliveRequest,

federationsender/inthttp/server.go

@@ -52,6 +52,20 @@ func AddRoutes(intAPI api.FederationSenderInternalAPI, internalAPIMux *mux.Route
 			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
 		}),
 	)
+	internalAPIMux.Handle(
+		FederationSenderPerformInviteRequestPath,
+		httputil.MakeInternalAPI("PerformInviteRequest", func(req *http.Request) util.JSONResponse {
+			var request api.PerformInviteRequest
+			var response api.PerformInviteResponse
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := intAPI.PerformInvite(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
 	internalAPIMux.Handle(
 		FederationSenderPerformDirectoryLookupRequestPath,
 		httputil.MakeInternalAPI("PerformDirectoryLookupRequest", func(req *http.Request) util.JSONResponse {

federationsender/queue/destinationqueue.go

@@ -46,20 +46,18 @@ type destinationQueue struct {
 	db                 storage.Database
 	signing            *SigningInfo
 	rsAPI              api.RoomserverInternalAPI
-	client             *gomatrixserverlib.FederationClient     // federation client
+	client             *gomatrixserverlib.FederationClient // federation client
-	origin             gomatrixserverlib.ServerName            // origin of requests
+	origin             gomatrixserverlib.ServerName        // origin of requests
-	destination        gomatrixserverlib.ServerName            // destination of requests
+	destination        gomatrixserverlib.ServerName        // destination of requests
-	running            atomic.Bool                             // is the queue worker running?
+	running            atomic.Bool                         // is the queue worker running?
-	backingOff         atomic.Bool                             // true if we're backing off
+	backingOff         atomic.Bool                         // true if we're backing off
-	statistics         *statistics.ServerStatistics            // statistics about this remote server
+	statistics         *statistics.ServerStatistics        // statistics about this remote server
-	incomingInvites    chan *gomatrixserverlib.InviteV2Request // invites to send
+	transactionIDMutex sync.Mutex                          // protects transactionID
-	transactionIDMutex sync.Mutex                              // protects transactionID
+	transactionID      gomatrixserverlib.TransactionID     // last transaction ID
-	transactionID      gomatrixserverlib.TransactionID         // last transaction ID
+	transactionCount   atomic.Int32                        // how many events in this transaction so far
-	transactionCount   atomic.Int32                            // how many events in this transaction so far
+	notifyPDUs         chan bool                           // interrupts idle wait for PDUs
-	pendingInvites     []*gomatrixserverlib.InviteV2Request    // owned by backgroundSend
+	notifyEDUs         chan bool                           // interrupts idle wait for EDUs
-	notifyPDUs         chan bool                               // interrupts idle wait for PDUs
+	interruptBackoff   chan bool                           // interrupts backoff
-	notifyEDUs         chan bool                               // interrupts idle wait for EDUs
-	interruptBackoff   chan bool                               // interrupts backoff
 }
 
 // Send event adds the event to the pending queue for the destination.
@@ -138,18 +136,6 @@ func (oq *destinationQueue) sendEDU(receipt *shared.Receipt) {
 	}
 }
 
-// sendInvite adds the invite event to the pending queue for the
-// destination. If the queue is empty then it starts a background
-// goroutine to start sending events to that destination.
-func (oq *destinationQueue) sendInvite(ev *gomatrixserverlib.InviteV2Request) {
-	if oq.statistics.Blacklisted() {
-		// If the destination is blacklisted then drop the event.
-		return
-	}
-	oq.wakeQueueIfNeeded()
-	oq.incomingInvites <- ev
-}
-
 // wakeQueueIfNeeded will wake up the destination queue if it is
 // not already running. If it is running but it is backing off
 // then we will interrupt the backoff, causing any federation
@@ -234,23 +220,6 @@ func (oq *destinationQueue) backgroundSend() {
 			// We were woken up because there are new PDUs waiting in the
 			// database.
 			pendingEDUs = true
-		case invite := <-oq.incomingInvites:
-			// There's no strict ordering requirement for invites like
-			// there is for transactions, so we put the invite onto the
-			// front of the queue. This means that if an invite that is
-			// stuck failing already, that it won't block our new invite
-			// from being sent.
-			oq.pendingInvites = append(
-				[]*gomatrixserverlib.InviteV2Request{invite},
-				oq.pendingInvites...,
-			)
-			// If there are any more things waiting in the channel queue
-			// then read them. This is safe because we guarantee only
-			// having one goroutine per destination queue, so the channel
-			// isn't being consumed anywhere else.
-			for len(oq.incomingInvites) > 0 {
-				oq.pendingInvites = append(oq.pendingInvites, <-oq.incomingInvites)
-			}
 		case <-time.After(queueIdleTimeout):
 			// The worker is idle so stop the goroutine. It'll get
 			// restarted automatically the next time we have an event to
@@ -266,7 +235,6 @@ func (oq *destinationQueue) backgroundSend() {
 			// It's been suggested that we should give up because the backoff
 			// has exceeded a maximum allowable value. Clean up the in-memory
 			// buffers at this point. The PDU clean-up is already on a defer.
-			oq.cleanPendingInvites()
 			log.Warnf("Blacklisting %q due to exceeding backoff threshold", oq.destination)
 			return
 		}
@@ -284,35 +252,9 @@ func (oq *destinationQueue) backgroundSend() {
 				oq.statistics.Success()
 			}
 		}
-
-		// Try sending the next invite and see what happens.
-		if len(oq.pendingInvites) > 0 {
-			sent, ierr := oq.nextInvites(oq.pendingInvites)
-			if ierr != nil {
-				// We failed to send the transaction. Mark it as a failure.
-				oq.statistics.Failure()
-			} else if sent > 0 {
-				// If we successfully sent the invites then clear out
-				// the pending invites.
-				oq.statistics.Success()
-				// Reallocate so that the underlying array can be GC'd, as
-				// opposed to growing forever.
-				oq.cleanPendingInvites()
-			}
-		}
 	}
 }
 
-// cleanPendingInvites cleans out the pending invite buffer,
-// removing all references so that the underlying objects can
-// be GC'd.
-func (oq *destinationQueue) cleanPendingInvites() {
-	for i := 0; i < len(oq.pendingInvites); i++ {
-		oq.pendingInvites[i] = nil
-	}
-	oq.pendingInvites = []*gomatrixserverlib.InviteV2Request{}
-}
-
 // nextTransaction creates a new transaction from the pending event
 // queue and sends it. Returns true if a transaction was sent or
 // false otherwise.
@@ -427,66 +369,3 @@ func (oq *destinationQueue) nextTransaction() (bool, error) {
 		return false, err
 	}
 }
-
-// nextInvite takes pending invite events from the queue and sends
-// them. Returns true if a transaction was sent or false otherwise.
-func (oq *destinationQueue) nextInvites(
-	pendingInvites []*gomatrixserverlib.InviteV2Request,
-) (int, error) {
-	done := 0
-	for _, inviteReq := range pendingInvites {
-		ev, roomVersion := inviteReq.Event(), inviteReq.RoomVersion()
-
-		log.WithFields(log.Fields{
-			"event_id":     ev.EventID(),
-			"room_version": roomVersion,
-			"destination":  oq.destination,
-		}).Info("sending invite")
-
-		inviteRes, err := oq.client.SendInviteV2(
-			context.TODO(),
-			oq.destination,
-			*inviteReq,
-		)
-		switch e := err.(type) {
-		case nil:
-			done++
-		case gomatrix.HTTPError:
-			log.WithFields(log.Fields{
-				"event_id":    ev.EventID(),
-				"state_key":   ev.StateKey(),
-				"destination": oq.destination,
-				"status_code": e.Code,
-			}).WithError(err).Error("failed to send invite due to HTTP error")
-			// Check whether we should do something about the error or
-			// just accept it as unavoidable.
-			if e.Code >= 400 && e.Code <= 499 {
-				// We tried but the remote side has sent back a client error.
-				// It's no use retrying because it will happen again.
-				done++
-				continue
-			}
-			return done, err
-		default:
-			log.WithFields(log.Fields{
-				"event_id":    ev.EventID(),
-				"state_key":   ev.StateKey(),
-				"destination": oq.destination,
-			}).WithError(err).Error("failed to send invite")
-			return done, err
-		}
-
-		invEv := inviteRes.Event.Sign(string(oq.signing.ServerName), oq.signing.KeyID, oq.signing.PrivateKey).Headered(roomVersion)
-		_, err = api.SendEvents(context.TODO(), oq.rsAPI, []gomatrixserverlib.HeaderedEvent{invEv}, oq.signing.ServerName, nil)
-		if err != nil {
-			log.WithFields(log.Fields{
-				"event_id":    ev.EventID(),
-				"state_key":   ev.StateKey(),
-				"destination": oq.destination,
-			}).WithError(err).Error("failed to return signed invite to roomserver")
-			return done, err
-		}
-	}
-
-	return done, nil
-}

federationsender/queue/queue.go

@@ -108,7 +108,6 @@ func (oqs *OutgoingQueues) getQueue(destination gomatrixserverlib.ServerName) *d
 			destination:      destination,
 			client:           oqs.client,
 			statistics:       oqs.statistics.ForServer(destination),
-			incomingInvites:  make(chan *gomatrixserverlib.InviteV2Request, 128),
 			notifyPDUs:       make(chan bool, 1),
 			notifyEDUs:       make(chan bool, 1),
 			interruptBackoff: make(chan bool),
@@ -178,51 +177,6 @@ func (oqs *OutgoingQueues) SendEvent(
 	return nil
 }
 
-// SendEvent sends an event to the destinations
-func (oqs *OutgoingQueues) SendInvite(
-	inviteReq *gomatrixserverlib.InviteV2Request,
-) error {
-	ev := inviteReq.Event()
-	stateKey := ev.StateKey()
-	if stateKey == nil {
-		log.WithFields(log.Fields{
-			"event_id": ev.EventID(),
-		}).Info("Invite had no state key, dropping")
-		return nil
-	}
-
-	_, destination, err := gomatrixserverlib.SplitID('@', *stateKey)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"event_id":  ev.EventID(),
-			"state_key": stateKey,
-		}).Info("Failed to split destination from state key")
-		return nil
-	}
-
-	if stateapi.IsServerBannedFromRoom(
-		context.TODO(),
-		oqs.stateAPI,
-		ev.RoomID(),
-		destination,
-	) {
-		log.WithFields(log.Fields{
-			"room_id":     ev.RoomID(),
-			"destination": destination,
-		}).Info("Dropping invite to server which is prohibited by ACLs")
-		return nil
-	}
-
-	log.WithFields(log.Fields{
-		"event_id":    ev.EventID(),
-		"server_name": destination,
-	}).Info("Sending invite")
-
-	oqs.getQueue(destination).sendInvite(inviteReq)
-
-	return nil
-}
-
 // SendEDU sends an EDU event to the destinations.
 func (oqs *OutgoingQueues) SendEDU(
 	e *gomatrixserverlib.EDU, origin gomatrixserverlib.ServerName,

roomserver/api/api.go

@@ -22,7 +22,7 @@ type RoomserverInternalAPI interface {
 		ctx context.Context,
 		req *PerformInviteRequest,
 		res *PerformInviteResponse,
-	)
+	) error
 
 	PerformJoin(
 		ctx context.Context,

roomserver/api/api_trace.go

@@ -33,9 +33,9 @@ func (t *RoomserverInternalAPITrace) PerformInvite(
 	ctx context.Context,
 	req *PerformInviteRequest,
 	res *PerformInviteResponse,
-) {
+) error {
-	t.Impl.PerformInvite(ctx, req, res)
 	util.GetLogger(ctx).Infof("PerformInvite req=%+v res=%+v", js(req), js(res))
+	return t.Impl.PerformInvite(ctx, req, res)
 }
 
 func (t *RoomserverInternalAPITrace) PerformJoin(

roomserver/api/perform.go

@@ -105,8 +105,6 @@ type PerformInviteRequest struct {
 }
 
 type PerformInviteResponse struct {
-	// If non-nil, the invite request failed. Contains more information why it failed.
-	Error *PerformError
 }
 
 // PerformBackfillRequest is a request to PerformBackfill.

roomserver/api/wrapper.go

@@ -99,22 +99,16 @@ func SendInvite(
 	rsAPI RoomserverInternalAPI, inviteEvent gomatrixserverlib.HeaderedEvent,
 	inviteRoomState []gomatrixserverlib.InviteV2StrippedState,
 	sendAsServer gomatrixserverlib.ServerName, txnID *TransactionID,
-) *PerformError {
+) error {
-	request := PerformInviteRequest{
+	request := &PerformInviteRequest{
 		Event:           inviteEvent,
 		InviteRoomState: inviteRoomState,
 		RoomVersion:     inviteEvent.RoomVersion,
 		SendAsServer:    string(sendAsServer),
 		TransactionID:   txnID,
 	}
-	var response PerformInviteResponse
+	response := &PerformInviteResponse{}
-	rsAPI.PerformInvite(ctx, &request, &response)
+	return rsAPI.PerformInvite(ctx, request, response)
-	// we need to do this because many places people will use `var err error` as the return
-	// arg and a nil interface != nil pointer to a concrete interface (in this case PerformError)
-	if response.Error != nil && response.Error.Msg != "" {
-		return response.Error
-	}
-	return nil
 }
 
 // GetEvent returns the event or nil, even on errors.

roomserver/internal/perform_invite.go

@@ -2,9 +2,9 @@ package internal
 
 import (
 	"context"
-	"errors"
 	"fmt"
 
+	federationSenderAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/state"
@@ -14,73 +14,50 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-// PerformInvite handles inviting to matrix rooms, including over federation by talking to the federationsender.
+// nolint:gocyclo
 func (r *RoomserverInternalAPI) PerformInvite(
 	ctx context.Context,
 	req *api.PerformInviteRequest,
 	res *api.PerformInviteResponse,
-) {
-	err := r.performInvite(ctx, req)
-	if err != nil {
-		perr, ok := err.(*api.PerformError)
-		if ok {
-			res.Error = perr
-		} else {
-			res.Error = &api.PerformError{
-				Msg: err.Error(),
-			}
-		}
-	}
-}
-
-func (r *RoomserverInternalAPI) performInvite(ctx context.Context,
-	req *api.PerformInviteRequest,
 ) error {
-	loopback, err := r.processInviteEvent(ctx, r, req)
+	event := req.Event
-	if err != nil {
+	if event.StateKey() == nil {
-		return err
+		return fmt.Errorf("invite must be a state event")
-	}
-	// The processInviteEvent function can optionally return a
-	// loopback room event containing the invite, for local invites.
-	// If it does, we should process it with the room events below.
-	if loopback != nil {
-		var loopbackRes api.InputRoomEventsResponse
-		err := r.InputRoomEvents(ctx, &api.InputRoomEventsRequest{
-			InputRoomEvents: []api.InputRoomEvent{*loopback},
-		}, &loopbackRes)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// nolint:gocyclo
-func (r *RoomserverInternalAPI) processInviteEvent(
-	ctx context.Context,
-	ow *RoomserverInternalAPI,
-	input *api.PerformInviteRequest,
-) (*api.InputRoomEvent, error) {
-	if input.Event.StateKey() == nil {
-		return nil, fmt.Errorf("invite must be a state event")
 	}
 
-	roomID := input.Event.RoomID()
+	roomID := event.RoomID()
-	targetUserID := *input.Event.StateKey()
+	targetUserID := *event.StateKey()
 
 	log.WithFields(log.Fields{
-		"event_id":       input.Event.EventID(),
+		"event_id":       event.EventID(),
 		"room_id":        roomID,
-		"room_version":   input.RoomVersion,
+		"room_version":   req.RoomVersion,
 		"target_user_id": targetUserID,
 	}).Info("processing invite event")
 
 	_, domain, _ := gomatrixserverlib.SplitID('@', targetUserID)
 	isTargetLocalUser := domain == r.Cfg.Matrix.ServerName
+	isOriginLocalUser := event.Origin() == r.Cfg.Matrix.ServerName
 
-	updater, err := r.DB.MembershipUpdater(ctx, roomID, targetUserID, isTargetLocalUser, input.RoomVersion)
+	// If the invite originated from us and the target isn't local then we
+	// should try and send the invite over federation first. It might be
+	// that the remote user doesn't exist, in which case we can give up
+	// processing here.
+	if isOriginLocalUser && !isTargetLocalUser {
+		fsReq := &federationSenderAPI.PerformInviteRequest{
+			RoomVersion: req.RoomVersion,
+			Event:       req.Event,
+		}
+		fsRes := &federationSenderAPI.PerformInviteResponse{}
+		if err := r.fsAPI.PerformInvite(ctx, fsReq, fsRes); err != nil {
+			return fmt.Errorf("r.fsAPI.PerformInvite: %w", err)
+		}
+		event = fsRes.SignedEvent
+	}
+
+	updater, err := r.DB.MembershipUpdater(ctx, roomID, targetUserID, isTargetLocalUser, req.RoomVersion)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	succeeded := false
 	defer func() {
@@ -118,109 +95,87 @@ func (r *RoomserverInternalAPI) processInviteEvent(
 		// For now we will implement option 2. Since in the abesence of a retry
 		// mechanism it will be equivalent to option 1, and we don't have a
 		// signalling mechanism to implement option 3.
-		return nil, &api.PerformError{
+		return &api.PerformError{
 			Code: api.PerformErrorNoOperation,
 			Msg:  "user is already joined to room",
 		}
 	}
 
-	// Normally, with a federated invite, the federation sender would do
-	// the /v2/invite request (in which the remote server signs the invite)
-	// and then the signed event gets sent back to the roomserver as an input
-	// event. When the invite is local, we don't interact with the federation
-	// sender therefore we need to generate the loopback invite event for
-	// the room ourselves.
-	loopback, err := localInviteLoopback(ow, input)
-	if err != nil {
-		return nil, err
-	}
-
-	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 {
+	if isOriginLocalUser {
-		_, err = checkAuthEvents(ctx, r.DB, input.Event, input.Event.AuthEventIDs())
+		_, err = checkAuthEvents(ctx, r.DB, req.Event, req.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{
+				return &api.PerformError{
 					Msg:  err.Error(),
 					Code: api.PerformErrorNotAllowed,
 				}
 			}
-			return nil, err
+			return err
 		}
 	}
 
-	if len(input.InviteRoomState) > 0 {
+	if len(req.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
 		// that.
-		if err = event.SetUnsignedField("invite_room_state", input.InviteRoomState); err != nil {
+		if err = event.SetUnsignedField("invite_room_state", req.InviteRoomState); err != nil {
-			return nil, err
+			return err
 		}
 	} else {
 		// There's no invite room state, so let's have a go at building it
 		// up from local data (which is most likely to be if the event came
 		// from the CS API). If we know about the room then we can insert
 		// the invite room state, if we don't then we just fail quietly.
-		if irs, ierr := buildInviteStrippedState(ctx, r.DB, input); ierr == nil {
+		if irs, ierr := buildInviteStrippedState(ctx, r.DB, req); ierr == nil {
 			if err = event.SetUnsignedField("invite_room_state", irs); err != nil {
-				return nil, err
+				return err
 			}
 		} else {
-			log.WithError(ierr).Error("failed to build invite stripped state")
+			log.WithError(ierr).Warn("failed to build invite stripped state")
 			// still set the field else synapse deployments don't process the invite
 			if err = event.SetUnsignedField("invite_room_state", struct{}{}); err != nil {
-				return nil, err
+				return err
 			}
 		}
 	}
 
-	outputUpdates, err := updateToInviteMembership(updater, &event, nil, input.Event.RoomVersion)
+	// If we're the sender of the event then we should send the invite
-	if err != nil {
+	// event into the room so that the room state is updated and other
-		return nil, err
+	// room participants will see the invite.
+	if isOriginLocalUser {
+		inputReq := &api.InputRoomEventsRequest{
+			InputRoomEvents: []api.InputRoomEvent{
+				{
+					Kind:         api.KindNew,
+					Event:        event,
+					AuthEventIDs: event.AuthEventIDs(),
+					SendAsServer: api.DoNotSendToOtherServers,
+				},
+			},
+		}
+		inputRes := &api.InputRoomEventsResponse{}
+		if err = r.InputRoomEvents(ctx, inputReq, inputRes); err != nil {
+			return fmt.Errorf("r.InputRoomEvents: %w", err)
+		}
 	}
 
-	if err = ow.WriteOutputEvents(roomID, outputUpdates); err != nil {
+	unwrapped := event.Unwrap()
-		return nil, err
+	outputUpdates, err := updateToInviteMembership(updater, &unwrapped, nil, req.Event.RoomVersion)
+	if err != nil {
+		return err
+	}
+
+	if err = r.WriteOutputEvents(roomID, outputUpdates); err != nil {
+		return err
 	}
 
 	succeeded = true
-	return loopback, nil
+	return nil
-}
-
-func localInviteLoopback(
-	ow *RoomserverInternalAPI,
-	input *api.PerformInviteRequest,
-) (ire *api.InputRoomEvent, err error) {
-	if input.Event.StateKey() == nil {
-		return nil, errors.New("no state key on invite event")
-	}
-	ourServerName := string(ow.Cfg.Matrix.ServerName)
-	_, theirServerName, err := gomatrixserverlib.SplitID('@', *input.Event.StateKey())
-	if err != nil {
-		return nil, err
-	}
-	// Check if the invite originated locally and is destined locally.
-	if input.Event.Origin() == ow.Cfg.Matrix.ServerName && string(theirServerName) == ourServerName {
-		rsEvent := input.Event.Sign(
-			ourServerName,
-			ow.Cfg.Matrix.KeyID,
-			ow.Cfg.Matrix.PrivateKey,
-		).Headered(input.RoomVersion)
-		ire = &api.InputRoomEvent{
-			Kind:          api.KindNew,
-			Event:         rsEvent,
-			AuthEventIDs:  rsEvent.AuthEventIDs(),
-			SendAsServer:  ourServerName,
-			TransactionID: nil,
-		}
-	}
-	return ire, nil
 }
 
 func buildInviteStrippedState(

roomserver/inthttp/client.go

@@ -154,17 +154,12 @@ func (h *httpRoomserverInternalAPI) PerformInvite(
 	ctx context.Context,
 	request *api.PerformInviteRequest,
 	response *api.PerformInviteResponse,
-) {
+) error {
 	span, ctx := opentracing.StartSpanFromContext(ctx, "PerformInvite")
 	defer span.Finish()
 
 	apiURL := h.roomserverURL + RoomserverPerformInvitePath
-	err := httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
-	if err != nil {
-		response.Error = &api.PerformError{
-			Msg: fmt.Sprintf("failed to communicate with roomserver: %s", err),
-		}
-	}
 }
 
 func (h *httpRoomserverInternalAPI) PerformJoin(