Feature: add an option to set udp timeout

engine/engine.go

@@ -10,6 +10,7 @@ import (
 	"github.com/xjasonlyu/tun2socks/log"
 	"github.com/xjasonlyu/tun2socks/proxy"
 	"github.com/xjasonlyu/tun2socks/stats"
+	"github.com/xjasonlyu/tun2socks/tunnel"
 )
 
 var _engine = &engine{}
@@ -32,6 +33,7 @@ func Insert(k *Key) {
 type Key struct {
 	MTU        int
 	Mark       int
+	UDPTimeout int
 	Proxy      string
 	Stats      string
 	Token      string
@@ -64,6 +66,7 @@ func (e *engine) start() error {
 		e.setMark,
 		e.setInterface,
 		e.setStats,
+		e.setUDPTimeout,
 		e.setProxy,
 		e.setDevice,
 		e.setStack,
@@ -123,6 +126,13 @@ func (e *engine) setStats() error {
 	return nil
 }
 
+func (e *engine) setUDPTimeout() error {
+	if e.UDPTimeout > 0 {
+		tunnel.SetUDPTimeout(e.UDPTimeout)
+	}
+	return nil
+}
+
 func (e *engine) setProxy() (err error) {
 	if e.Proxy == "" {
 		return errors.New("empty proxy")

main.go

@@ -15,6 +15,7 @@ var key = new(engine.Key)
 func init() {
 	flag.IntVar(&key.Mark, "fwmark", 0, "Set firewall MARK (Linux only)")
 	flag.IntVar(&key.MTU, "mtu", 0, "Set device maximum transmission unit (MTU)")
+	flag.IntVar(&key.UDPTimeout, "udp-timeout", 0, "Set timeout for each UDP session")
 	flag.BoolVar(&key.Version, "version", false, "Show version information and quit")
 	flag.StringVar(&key.Device, "device", "", "Use this device [driver://]name")
 	flag.StringVar(&key.Interface, "interface", "", "Use network INTERFACE (Linux/MacOS only)")

tunnel/udp.go

@@ -16,16 +16,20 @@ import (
 	"github.com/xjasonlyu/tun2socks/tunnel/statistic"
 )
 
-const (
-	udpSessionTimeout = 60 * time.Second
-)
-
 var (
 	// _natTable uses source udp packet information
 	// as key to store destination udp packetConn.
 	_natTable = nat.NewTable()
+
+	// _udpSessionTimeout is the default timeout for
+	// each UDP session.
+	_udpSessionTimeout = 60 * time.Second
 )
 
+func SetUDPTimeout(v int) {
+	_udpSessionTimeout = time.Duration(v) * time.Second
+}
+
 func newUDPTracker(conn net.PacketConn, metadata *M.Metadata) net.PacketConn {
 	return statistic.NewUDPTracker(conn, metadata, statistic.DefaultManager)
 }
@@ -115,7 +119,7 @@ func handleUDPToRemote(packet core.UDPPacket, pc net.PacketConn, remote net.Addr
 	if _, err := pc.WriteTo(packet.Data() /* data */, remote); err != nil {
 		log.Warnf("[UDP] write to %s error: %v", remote, err)
 	}
-	pc.SetReadDeadline(time.Now().Add(udpSessionTimeout)) /* reset timeout */
+	pc.SetReadDeadline(time.Now().Add(_udpSessionTimeout)) /* reset timeout */
 
 	log.Infof("[UDP] %s --> %s", packet.RemoteAddr(), remote)
 }
@@ -125,7 +129,7 @@ func handleUDPToLocal(packet core.UDPPacket, pc net.PacketConn) {
 	defer pool.Put(buf)
 
 	for /* just loop */ {
-		pc.SetReadDeadline(time.Now().Add(udpSessionTimeout))
+		pc.SetReadDeadline(time.Now().Add(_udpSessionTimeout))
 		n, from, err := pc.ReadFrom(buf)
 		if err != nil {
 			if !errors.Is(err, os.ErrDeadlineExceeded) /* ignore i/o timeout */ {