Fix(socks5): fully udp associate support (#233)

proxy/listener.go

@@ -13,9 +13,10 @@ import (
 var (
 	allowLan = false
 
-	socksListener *socks.SockListener
-	httpListener  *http.HttpListener
-	redirListener *redir.RedirListener
+	socksListener    *socks.SockListener
+	socksUDPListener *socks.SockUDPListener
+	httpListener     *http.HttpListener
+	redirListener    *redir.RedirListener
 )
 
 type listener interface {
@@ -82,6 +83,30 @@ func ReCreateSocks(port int) error {
 		return err
 	}
 
+	return reCreateSocksUDP(port)
+}
+
+func reCreateSocksUDP(port int) error {
+	addr := genAddr(port, allowLan)
+
+	if socksUDPListener != nil {
+		if socksUDPListener.Address() == addr {
+			return nil
+		}
+		socksUDPListener.Close()
+		socksUDPListener = nil
+	}
+
+	if portIsZero(addr) {
+		return nil
+	}
+
+	var err error
+	socksUDPListener, err = socks.NewSocksUDPProxy(addr)
+	if err != nil {
+		return err
+	}
+
 	return nil
 }
 

proxy/socks/tcp.go

@@ -1,6 +1,8 @@
 package socks
 
 import (
+	"io"
+	"io/ioutil"
 	"net"
 
 	adapters "github.com/Dreamacro/clash/adapters/inbound"
@@ -62,7 +64,8 @@ func handleSocks(conn net.Conn) {
 	}
 	conn.(*net.TCPConn).SetKeepAlive(true)
 	if command == socks5.CmdUDPAssociate {
-		tun.Add(adapters.NewSocket(target, conn, C.SOCKS, C.UDP))
+		defer conn.Close()
+		io.Copy(ioutil.Discard, conn)
 		return
 	}
 	tun.Add(adapters.NewSocket(target, conn, C.SOCKS, C.TCP))

proxy/socks/udp.go

@@ -0,0 +1,65 @@
+package socks
+
+import (
+	"net"
+
+	adapters "github.com/Dreamacro/clash/adapters/inbound"
+	"github.com/Dreamacro/clash/common/pool"
+	"github.com/Dreamacro/clash/component/socks5"
+	C "github.com/Dreamacro/clash/constant"
+	"github.com/Dreamacro/clash/tunnel"
+)
+
+var (
+	_ = tunnel.NATInstance()
+)
+
+type SockUDPListener struct {
+	net.PacketConn
+	address string
+	closed  bool
+}
+
+func NewSocksUDPProxy(addr string) (*SockUDPListener, error) {
+	l, err := net.ListenPacket("udp", addr)
+	if err != nil {
+		return nil, err
+	}
+
+	sl := &SockUDPListener{l, addr, false}
+	go func() {
+		buf := pool.BufPool.Get().([]byte)
+		defer pool.BufPool.Put(buf[:cap(buf)])
+		for {
+			n, remoteAddr, err := l.ReadFrom(buf)
+			if err != nil {
+				if sl.closed {
+					break
+				}
+				continue
+			}
+			go handleSocksUDP(l, buf[:n], remoteAddr)
+		}
+	}()
+
+	return sl, nil
+}
+
+func (l *SockUDPListener) Close() error {
+	l.closed = true
+	return l.PacketConn.Close()
+}
+
+func (l *SockUDPListener) Address() string {
+	return l.address
+}
+
+func handleSocksUDP(c net.PacketConn, packet []byte, remoteAddr net.Addr) {
+	target, payload, err := socks5.DecodeUDPPacket(packet)
+	if err != nil {
+		// Unresolved UDP packet, do nothing
+		return
+	}
+	conn := newfakeConn(c, target.String(), remoteAddr, payload)
+	tun.Add(adapters.NewSocket(target, conn, C.SOCKS, C.UDP))
+}

proxy/socks/utils.go

@@ -0,0 +1,41 @@
+package socks
+
+import (
+	"bytes"
+	"net"
+
+	"github.com/Dreamacro/clash/component/socks5"
+)
+
+type fakeConn struct {
+	net.PacketConn
+	target     string
+	remoteAddr net.Addr
+	buffer     *bytes.Buffer
+}
+
+func newfakeConn(conn net.PacketConn, target string, remoteAddr net.Addr, buf []byte) *fakeConn {
+	buffer := bytes.NewBuffer(buf)
+	return &fakeConn{
+		PacketConn: conn,
+		target:     target,
+		buffer:     buffer,
+		remoteAddr: remoteAddr,
+	}
+}
+
+func (c *fakeConn) Read(b []byte) (n int, err error) {
+	return c.buffer.Read(b)
+}
+
+func (c *fakeConn) Write(b []byte) (n int, err error) {
+	packet, err := socks5.EncodeUDPPacket(c.target, b)
+	if err != nil {
+		return
+	}
+	return c.PacketConn.WriteTo(packet, c.remoteAddr)
+}
+
+func (c *fakeConn) RemoteAddr() net.Addr {
+	return c.remoteAddr
+}