From 1c245bd453976e9f175a20c33078a20ea7dc4ab5 Mon Sep 17 00:00:00 2001
From: set <set>
Date: Wed, 11 Mar 2026 19:32:00 +0200
Subject: [PATCH] =?UTF-8?q?=D0=9F=D0=B5=D1=80=D0=B5=D1=81=D1=8B=D0=BB?=
 =?UTF-8?q?=D0=BA=D0=B0=20RTP=20=D0=BF=D0=B0=D0=BA=D0=B5=D1=82=D0=BE=D0=B2?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 sfu/forwarding.go | 116 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 sfu/forwarding.go

diff --git a/sfu/forwarding.go b/sfu/forwarding.go
new file mode 100644
index 0000000..2256317
--- /dev/null
+++ b/sfu/forwarding.go
@@ -0,0 +1,116 @@
+package sfu
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/pion/webrtc/v4"
+)
+
+// SFU -> Java signaling: отправить server-offer для конкретного peer
+var OnServerOffer func(roomID string, peerID string, offer webrtc.SessionDescription)
+
+// Вызывается при JoinWithOffer для ретрансляции RTP пакетов от издателя к другим участникам комнаты
+func SetupForwardingForPeer(roomID string, publisherPeerID string, publisherPC *webrtc.PeerConnection) {
+	publisherPC.OnTrack(func(remote *webrtc.TrackRemote, _ *webrtc.RTPReceiver) {
+		localTrack, err := webrtc.NewTrackLocalStaticRTP(
+			remote.Codec().RTPCodecCapability,
+			fmt.Sprintf("%s:%s", publisherPeerID, remote.ID()),
+			remote.StreamID(),
+		)
+		if err != nil {
+			return
+		}
+
+		// Добавляем этот track всем, кроме publisher
+		roomsMu.RLock()
+		room, ok := rooms[roomID]
+		if !ok {
+			roomsMu.RUnlock()
+			return
+		}
+		peers := make([]Peer, len(room.Peers))
+		copy(peers, room.Peers)
+		roomsMu.RUnlock()
+
+		for _, sub := range peers {
+			if sub.PeerID == publisherPeerID {
+				continue
+			}
+
+			sender, err := sub.PeerConnection.AddTrack(localTrack)
+			if err != nil {
+				continue
+			}
+
+			// RTCP drain обязателен
+			go func() {
+				buf := make([]byte, 1500)
+				for {
+					if _, _, e := sender.Read(buf); e != nil {
+						return
+					}
+				}
+			}()
+
+			// После AddTrack нужна renegotiation для подписчика
+			_ = renegotiatePeer(roomID, sub.PeerID, sub.PeerConnection)
+		}
+
+		// Пересылаем RTP пакеты от издателя всем подписчикам
+		for {
+			pkt, _, err := remote.ReadRTP()
+			if err != nil {
+				if err == io.EOF {
+					return
+				}
+				return
+			}
+			if err = localTrack.WriteRTP(pkt); err != nil {
+				return
+			}
+		}
+	})
+}
+
+func renegotiatePeer(roomID, peerID string, pc *webrtc.PeerConnection) error {
+	offer, err := pc.CreateOffer(nil)
+	if err != nil {
+		return err
+	}
+
+	gatherDone := webrtc.GatheringCompletePromise(pc)
+	if err = pc.SetLocalDescription(offer); err != nil {
+		return err
+	}
+	<-gatherDone
+
+	if OnServerOffer != nil && pc.LocalDescription() != nil {
+		OnServerOffer(roomID, peerID, *pc.LocalDescription())
+	}
+	return nil
+}
+
+// Java -> SFU: answer клиента на server-offer
+func HandleClientAnswer(roomID, peerID string, answer webrtc.SessionDescription) error {
+	roomsMu.RLock()
+	room, ok := rooms[roomID]
+	if !ok {
+		roomsMu.RUnlock()
+		return ErrRoomNotFound
+	}
+
+	var pc *webrtc.PeerConnection
+	for _, p := range room.Peers {
+		if p.PeerID == peerID {
+			pc = p.PeerConnection
+			break
+		}
+	}
+	roomsMu.RUnlock()
+
+	if pc == nil {
+		return ErrPeerNotFound
+	}
+	return pc.SetRemoteDescription(answer)
+}