Исправлена гонка записи в сокет

sfu/forwarding.go

@@ -3,10 +3,31 @@ package sfu
 import (
 	"fmt"
 	"io"
+	"strings"
+	"sync"
 
 	"github.com/pion/webrtc/v4"
 )
 
+var (
+	pendingMu         sync.Mutex
+	pendingCandidates = map[string][]webrtc.ICECandidateInit{} // key: roomID|peerID
+)
+
+func peerKey(roomID, peerID string) string {
+	return roomID + "|" + peerID
+}
+
+func extractICEUfrag(sdp string) string {
+	for _, line := range strings.Split(sdp, "\n") {
+		line = strings.TrimSpace(line)
+		if strings.HasPrefix(line, "a=ice-ufrag:") {
+			return strings.TrimPrefix(line, "a=ice-ufrag:")
+		}
+	}
+	return ""
+}
+
 // 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) {
@@ -95,21 +116,47 @@ func AddICECandidate(roomID string, peerID string, candidate webrtc.ICECandidate
 		return ErrRoomNotFound
 	}
 
-	for _, peer := range room.Peers {
-		if peer.PeerID == peerID {
-			return peer.PeerConnection.AddICECandidate(candidate)
+	var pc *webrtc.PeerConnection
+	for _, p := range room.Peers {
+		if p.PeerID == peerID {
+			pc = p.PeerConnection
+			break
+		}
+	}
+	if pc == nil {
+		return ErrPeerNotFound
+	}
+
+	rd := pc.RemoteDescription()
+	if rd == nil {
+		// answer/offer еще не применен — буферизуем
+		pendingMu.Lock()
+		k := peerKey(roomID, peerID)
+		pendingCandidates[k] = append(pendingCandidates[k], candidate)
+		pendingMu.Unlock()
+		return nil
+	}
+
+	// отбрасываем stale candidate по ufrag
+	if candidate.UsernameFragment != nil {
+		current := extractICEUfrag(rd.SDP)
+		if current != "" && *candidate.UsernameFragment != current {
+			return nil
 		}
 	}
 
-	return ErrPeerNotFound
+	err := pc.AddICECandidate(candidate)
+	if err != nil && strings.Contains(err.Error(), "doesn't match the current ufrags") {
+		// поздний старый кандидат — игнорируем
+		return nil
+	}
+	return err
 }
 
 // Обрабатывает SDP ответ от клиента при renegotiation
 func HandleClientAnswer(roomID string, peerID string, answer webrtc.SessionDescription) error {
-	roomsMu.RLock()
-	room, ok := rooms[roomID]
-	if !ok {
-		roomsMu.RUnlock()
+	room, exists := GetRoom(roomID)
+	if !exists {
 		return ErrRoomNotFound
 	}
 
@@ -120,10 +167,24 @@ func HandleClientAnswer(roomID string, peerID string, answer webrtc.SessionDescr
 			break
 		}
 	}
-	roomsMu.RUnlock()
-
 	if pc == nil {
 		return ErrPeerNotFound
 	}
-	return pc.SetRemoteDescription(answer)
+
+	if err := pc.SetRemoteDescription(answer); err != nil {
+		return err
+	}
+
+	// после применения answer — применяем отложенные кандидаты
+	k := peerKey(roomID, peerID)
+	pendingMu.Lock()
+	queue := pendingCandidates[k]
+	delete(pendingCandidates, k)
+	pendingMu.Unlock()
+
+	for _, c := range queue {
+		_ = AddICECandidate(roomID, peerID, c)
+	}
+
+	return nil
 }