snapshot of https://github.com/livekit/livekit.git @ 08c5433449c106943231037d0b892895f6e92d3b (2026-09-15)

pkg/rtc/signalling/signallerasync.go

@@ -0,0 +1,140 @@
+// Copyright 2023 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package signalling
+
+import (
+	"fmt"
+
+	"github.com/livekit/protocol/livekit"
+	"github.com/livekit/protocol/logger"
+	"github.com/livekit/protocol/utils"
+	"github.com/livekit/psrpc"
+
+	"github.com/livekit/livekit-server/pkg/routing"
+	"github.com/livekit/livekit-server/pkg/rtc/types"
+
+	"google.golang.org/protobuf/proto"
+)
+
+var _ ParticipantSignaller = (*signallerAsync)(nil)
+
+type SignallerAsyncParams struct {
+	Logger            logger.Logger
+	Participant       types.LocalParticipant
+	OnHandshakeOpened func()
+}
+
+type signallerAsync struct {
+	params SignallerAsyncParams
+
+	*signallerAsyncBase
+}
+
+func NewSignallerAsync(params SignallerAsyncParams) ParticipantSignaller {
+	return &signallerAsync{
+		params: params,
+		signallerAsyncBase: newSignallerAsyncBase(signallerAsyncBaseParams{
+			Logger:            params.Logger,
+			OnHandshakeOpened: params.OnHandshakeOpened,
+		}),
+	}
+}
+
+func (s *signallerAsync) WriteMessage(msg proto.Message) error {
+	if msg == nil {
+		return nil
+	}
+
+	getMessageType := func(msg proto.Message) string {
+		messageType := "unknown"
+		if typed, ok := msg.(*livekit.SignalResponse); ok {
+			messageType = fmt.Sprintf("%T", typed.Message)
+		}
+		return messageType
+	}
+
+	if s.params.Participant.IsDisconnected() {
+		s.params.Logger.Debugw(
+			"could not send message to participant, participant disconnected",
+			"messageType", getMessageType(msg),
+		)
+		return nil
+	}
+
+	// a signal connection opens with a join response, or with a reconnect response when
+	// it is resumed or migrated in. The client reads that first message as the handshake,
+	// so nothing may go out ahead of it.
+	isHandshake := false
+	isSdp := false
+	if typed, ok := msg.(*livekit.SignalResponse); !ok {
+		s.params.Logger.Warnw(
+			"unknown message type", nil,
+			"messageType", fmt.Sprintf("%T", msg),
+		)
+	} else {
+		isHandshake = typed.GetJoin() != nil || typed.GetReconnect() != nil
+		isSdp = typed.GetOffer() != nil || typed.GetAnswer() != nil
+	}
+
+	if !isHandshake && (!s.params.Participant.IsReady() || s.HandshakePending()) {
+		logFunc := s.params.Logger.Debugw
+		if isSdp {
+			// a dropped SDP leaves the negotiation waiting for the peer until the
+			// negotiation state machine recovers it, so make it visible
+			logFunc = func(msg string, keysAndValues ...any) {
+				s.params.Logger.Infow(msg, keysAndValues...)
+			}
+		}
+		logFunc(
+			"dropping message, connection has not opened yet",
+			"messageType", getMessageType(msg),
+		)
+		return nil
+	}
+
+	sink := s.GetResponseSink()
+	if sink == nil {
+		s.params.Logger.Debugw(
+			"could not send message to participant, no sink",
+			"messageType", getMessageType(msg),
+		)
+		return nil
+	}
+
+	err := sink.WriteMessage(msg)
+	if err != nil {
+		if utils.ErrorIsOneOf(err, psrpc.Canceled, routing.ErrChannelClosed) {
+			s.params.Logger.Debugw(
+				"could not send message to participant",
+				"error", err,
+				"messageType", getMessageType(msg),
+			)
+			return nil
+		} else {
+			s.params.Logger.Warnw(
+				"could not send message to participant", err,
+				"messageType", getMessageType(msg),
+			)
+			return err
+		}
+	} else {
+		if isHandshake {
+			// the connection is open, hold nothing back any more
+			s.OpenHandshake()
+		}
+		s.params.Logger.Debugw("sent signal response", "response", logger.Proto(msg))
+	}
+	return nil
+}