From cde5fc119df314d221bd219a0276c89f77bab0b7 Mon Sep 17 00:00:00 2001
From: boks1971 <raja.gobi@tutanota.com>
Date: Thu, 14 Aug 2025 19:52:24 +0530
Subject: [PATCH] WIP

---
 pkg/rtc/participant.go |  8 ++++++++
 pkg/rtc/transport.go   | 25 +++++++++++++++++++++++++
 test/client/client.go  | 26 +++++++++++++++++---------
 3 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/pkg/rtc/participant.go b/pkg/rtc/participant.go
index def208e51..18322e4d7 100644
--- a/pkg/rtc/participant.go
+++ b/pkg/rtc/participant.go
@@ -1869,6 +1869,14 @@ func (h SubscriberTransportHandler) OnInitialConnected() {
 	h.p.onSubscriberInitialConnected()
 }
 
+func (h SubscriberTransportHandler) OnDataMessage(kind livekit.DataPacket_Kind, data []byte) {
+	h.p.onReceivedDataMessage(kind, data)
+}
+
+func (h SubscriberTransportHandler) OnDataMessageUnlabeled(data []byte) {
+	h.p.onReceivedDataMessageUnlabeled(data)
+}
+
 func (h SubscriberTransportHandler) OnDataSendError(err error) {
 	h.p.onDataSendError(err)
 }
diff --git a/pkg/rtc/transport.go b/pkg/rtc/transport.go
index 9fb51a12c..ff55b4c93 100644
--- a/pkg/rtc/transport.go
+++ b/pkg/rtc/transport.go
@@ -1096,6 +1096,7 @@ func (t *PCTransport) CreateDataChannel(label string, dci *webrtc.DataChannelIni
 		dcPtr       **datachannel.DataChannelWriter[*webrtc.DataChannel]
 		dcReady     *bool
 		isUnlabeled bool
+		kind        livekit.DataPacket_Kind
 	)
 	switch dc.Label() {
 	default:
@@ -1104,9 +1105,11 @@ func (t *PCTransport) CreateDataChannel(label string, dci *webrtc.DataChannelIni
 	case ReliableDataChannel:
 		dcPtr = &t.reliableDC
 		dcReady = &t.reliableDCOpened
+		kind = livekit.DataPacket_RELIABLE
 	case LossyDataChannel:
 		dcPtr = &t.lossyDC
 		dcReady = &t.lossyDCOpened
+		kind = livekit.DataPacket_LOSSY
 	}
 
 	dc.OnOpen(func() {
@@ -1137,6 +1140,28 @@ func (t *PCTransport) CreateDataChannel(label string, dci *webrtc.DataChannelIni
 		t.lock.Unlock()
 		t.params.Logger.Debugw(dc.Label() + " data channel open")
 
+		go func() {
+			defer rawDC.Close()
+			buffer := make([]byte, dataChannelBufferSize)
+			for {
+				n, _, err := rawDC.ReadDataChannel(buffer)
+				if err != nil {
+					if !errors.Is(err, io.EOF) && !strings.Contains(err.Error(), "state=Closed") {
+						t.params.Logger.Warnw("error reading data channel", err, "label", dc.Label())
+					}
+					return
+				}
+
+				switch {
+				case isUnlabeled:
+					t.params.Handler.OnDataMessageUnlabeled(buffer[:n])
+
+				default:
+					t.params.Handler.OnDataMessage(kind, buffer[:n])
+				}
+			}
+		}()
+
 		t.maybeNotifyFullyEstablished()
 	})
 
diff --git a/test/client/client.go b/test/client/client.go
index 32b5540c3..e856c2ac6 100644
--- a/test/client/client.go
+++ b/test/client/client.go
@@ -55,10 +55,11 @@ type SignalResponseHandler func(msg *livekit.SignalResponse) error
 type SignalResponseInterceptor func(msg *livekit.SignalResponse, next SignalResponseHandler) error
 
 type RTCClient struct {
-	id         livekit.ParticipantID
-	conn       *websocket.Conn
-	publisher  *rtc.PCTransport
-	subscriber *rtc.PCTransport
+	protocolVersion types.ProtocolVersion
+	id              livekit.ParticipantID
+	conn            *websocket.Conn
+	publisher       *rtc.PCTransport
+	subscriber      *rtc.PCTransport
 	// sid => track
 	localTracks        map[string]webrtc.TrackLocal
 	trackSenders       map[string]*webrtc.RTPSender
@@ -206,6 +207,7 @@ func NewRTCClient(conn *websocket.Conn, opts *Options) (*RTCClient, error) {
 	var err error
 
 	c := &RTCClient{
+		protocolVersion:        types.CurrentProtocol,
 		conn:                   conn,
 		localTracks:            make(map[string]webrtc.TrackLocal),
 		trackSenders:           make(map[string]*webrtc.RTPSender),
@@ -684,7 +686,7 @@ func (c *RTCClient) AddTrack(track *webrtc.TrackLocalStaticSample, path string,
 	}
 
 	var sender *webrtc.RTPSender
-	if types.ProtocolVersion(types.CurrentProtocol).SupportsSinglePeerConnection() {
+	if c.protocolVersion.SupportsSinglePeerConnection() {
 		sender, _, err = c.subscriber.AddTrack(track, types.AddTrackParams{})
 	} else {
 		sender, _, err = c.publisher.AddTrack(track, types.AddTrackParams{})
@@ -753,7 +755,7 @@ func (c *RTCClient) AddTrack(track *webrtc.TrackLocalStaticSample, path string,
 	*/
 	c.localTracks[ti.Sid] = track
 	c.trackSenders[ti.Sid] = sender
-	if !types.ProtocolVersion(types.CurrentProtocol).SupportsSinglePeerConnection() {
+	if !c.protocolVersion.SupportsSinglePeerConnection() {
 		c.publisher.Negotiate(false)
 	}
 
@@ -827,8 +829,10 @@ func (c *RTCClient) SendAddTrack(cid string, mimeType string, name string, track
 }
 
 func (c *RTCClient) PublishData(data []byte, kind livekit.DataPacket_Kind) error {
-	if err := c.ensurePublisherConnected(); err != nil {
-		return err
+	if !c.protocolVersion.SupportsSinglePeerConnection() {
+		if err := c.ensurePublisherConnected(); err != nil {
+			return err
+		}
 	}
 
 	dpData, err := proto.Marshal(&livekit.DataPacket{
@@ -840,7 +844,11 @@ func (c *RTCClient) PublishData(data []byte, kind livekit.DataPacket_Kind) error
 		return err
 	}
 
-	return c.publisher.SendDataMessage(kind, dpData)
+	if !c.protocolVersion.SupportsSinglePeerConnection() {
+		return c.publisher.SendDataMessage(kind, dpData)
+	} else {
+		return c.subscriber.SendDataMessage(kind, dpData)
+	}
 }
 
 func (c *RTCClient) PublishDataUnlabeled(data []byte) error {