fix: 添加relay日志

cmd/internal/transport/kcp.go

@@ -196,15 +196,26 @@ func generateKCPConversationID() (uint32, error) {
 	return convID, nil
 }
 
-func listenKCPPacketConn(listenAddr, bindDevice string, logger KCPPacketDebugLogger, nodeRole, nodeID string) (net.PacketConn, error) {
+// ResolveUDPListenConfig parses a UDP listen address and returns the socket
+// family that should be used for binding it.
+func ResolveUDPListenConfig(listenAddr string) (string, *net.UDPAddr, error) {
 	udpAddr, err := net.ResolveUDPAddr("udp", listenAddr)
+	if err != nil {
+		return "", nil, fmt.Errorf("transport: resolve udp listen addr %s: %w", listenAddr, err)
+	}
+
+	return udpListenNetwork(udpAddr), udpAddr, nil
+}
+
+func listenKCPPacketConn(listenAddr, bindDevice string, logger KCPPacketDebugLogger, nodeRole, nodeID string) (net.PacketConn, error) {
+	network, udpAddr, err := ResolveUDPListenConfig(listenAddr)
 	if err != nil {
 		return nil, fmt.Errorf("transport: resolve kcp listen addr %s: %w", listenAddr, err)
 	}
 
-	rawConn, err := listenUDPConn("udp", udpAddr, bindDevice)
+	rawConn, err := listenUDPConn(network, udpAddr, bindDevice)
 	if err != nil {
-		return nil, fmt.Errorf("transport: listen udp for kcp on %s: %w", listenAddr, err)
+		return nil, fmt.Errorf("transport: listen %s for kcp on %s: %w", network, udpListenAddr(udpAddr), err)
 	}
 
 	packetConn, err := newKCPPacketConn(rawConn, logger, nodeRole, nodeID)
@@ -280,3 +291,13 @@ func udpListenAddr(addr *net.UDPAddr) string {
 	}
 	return addr.String()
 }
+
+func udpListenNetwork(addr *net.UDPAddr) string {
+	if addr == nil || addr.IP == nil {
+		return "udp"
+	}
+	if addr.IP.To4() != nil {
+		return "udp4"
+	}
+	return "udp6"
+}