ss: support udp forward chain

direct.go

@@ -30,15 +30,15 @@ func (d *direct) Dial(network, addr string) (net.Conn, error) {
 }
 
 // DialUDP connects to the given address via the proxy.
-func (d *direct) DialUDP(network, addr string) (pc net.PacketConn, writeTo net.Addr, err error) {
+func (d *direct) DialUDP(network, addr string) (net.PacketConn, net.Addr, error) {
-	pc, err = net.ListenPacket(network, "")
+	pc, err := net.ListenPacket(network, "")
 	if err != nil {
 		logf("ListenPacket error: %s", err)
 		return nil, nil, err
 	}
 
 	uAddr, err := net.ResolveUDPAddr("udp", addr)
-	return pc, uAddr, nil
+	return pc, uAddr, err
 }
 
 func (d *direct) NextDialer(dstAddr string) Dialer { return d }

forwarder.go

@@ -25,6 +25,11 @@ func (p *Forwarder) Dial(network, addr string) (net.Conn, error) {
 	return p.cDialer.Dial(network, addr)
 }
 
+// DialUDP to remote addr via cDialer
+func (p *Forwarder) DialUDP(network, addr string) (pc net.PacketConn, writeTo net.Addr, err error) {
+	return p.cDialer.DialUDP(network, addr)
+}
+
 // NextDialer returns the next cDialer
 func (p *Forwarder) NextDialer(dstAddr string) Dialer {
 	return p.cDialer

ss.go

@@ -5,7 +5,6 @@ import (
 	"log"
 	"net"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/shadowsocks/go-shadowsocks2/core"
@@ -139,7 +138,6 @@ func (s *SS) ServeTCP(c net.Conn) {
 }
 
 // ListenAndServeUDP serves udp ss requests.
-// TODO: Forwarder chain not supported now.
 func (s *SS) ListenAndServeUDP() {
 	c, err := net.ListenPacket("udp", s.addr)
 	if err != nil {
@@ -151,8 +149,6 @@ func (s *SS) ListenAndServeUDP() {
 	logf("proxy-ss-udp listening UDP on %s", s.addr)
 
 	c = s.PacketConn(c)
-
-	var nm sync.Map
 	buf := make([]byte, udpBufSize)
 
 	for {
@@ -168,41 +164,34 @@ func (s *SS) ListenAndServeUDP() {
 			continue
 		}
 
-		tgtUDPAddr, err := net.ResolveUDPAddr("udp", tgtAddr.String())
-		if err != nil {
-			logf("proxy-ss-udp failed to resolve target UDP address: %v", err)
-			continue
-		}
-
 		logf("proxy-ss-udp %s <-> %s", raddr, tgtAddr)
 
 		payload := buf[len(tgtAddr):n]
 
-		var pc net.PacketConn
+		rc, nexHop, err := s.sDialer.DialUDP("udp", tgtAddr.String())
-		v, ok := nm.Load(raddr.String())
-		if !ok && v == nil {
-			pc, err = net.ListenPacket("udp", "")
 		if err != nil {
 			logf("proxy-ss-udp remote listen error: %v", err)
 			continue
 		}
 
-			nm.Store(raddr.String(), pc)
+		_, err = rc.WriteTo(payload, nexHop) // accept only UDPAddr despite the signature
-			go func() {
-				timedCopy(c, raddr, pc, 5*time.Minute, true)
-				pc.Close()
-				nm.Delete(raddr.String())
-			}()
-		} else {
-			pc = v.(net.PacketConn)
-		}
-
-		_, err = pc.WriteTo(payload, tgtUDPAddr) // accept only UDPAddr despite the signature
 		if err != nil {
 			logf("proxy-ss-udp remote write error: %v", err)
 			continue
 		}
 
+		rcBuf := make([]byte, udpBufSize)
+		rc.SetReadDeadline(time.Now().Add(time.Minute))
+		copy(rcBuf, tgtAddr)
+
+		n, _, err = rc.ReadFrom(rcBuf[len(tgtAddr):])
+		if err != nil {
+			logf("proxy-ss-udp rc.Read error: %v", err)
+			return
+		}
+		rc.Close()
+
+		c.WriteTo(rcBuf[:len(tgtAddr)+n], raddr)
 	}
 
 }
@@ -244,20 +233,15 @@ func (s *SS) Dial(network, addr string) (net.Conn, error) {
 }
 
 // DialUDP connects to the given address via the proxy.
-func (s *SS) DialUDP(network, addr string) (pc net.PacketConn, writeTo net.Addr, err error) {
+func (s *SS) DialUDP(network, addr string) (net.PacketConn, net.Addr, error) {
-	// TODO: check forward chain
+	pc, nextHop, err := s.cDialer.DialUDP(network, s.addr)
-	pc, nextHop, err := s.cDialer.DialUDP(network, addr)
 	if err != nil {
-		logf("proxy-ss dialudp to %s error: %s", addr, err)
+		logf("proxy-ss dialudp to %s error: %s", s.addr, err)
 		return nil, nil, err
 	}
 
-	nextHopAddr := ParseAddr(nextHop.String())
+	pkc := NewPktConn(s.PacketConn(pc), nextHop, ParseAddr(addr), true)
-	writeTo, err = net.ResolveUDPAddr("udp", s.Addr())
+	return pkc, nextHop, err
-
-	pkc := NewPktConn(s.PacketConn(pc), writeTo, nextHopAddr, true)
-
-	return pkc, writeTo, err
 }
 
 // PktConn wraps a net.PacketConn and support Write method like net.Conn
@@ -271,7 +255,6 @@ type PktConn struct {
 
 // NewPktConn returns a PktConn
 func NewPktConn(c net.PacketConn, addr net.Addr, target Addr, tgtHeader bool) *PktConn {
-
 	pc := &PktConn{
 		PacketConn: c,
 		addr:       addr,
@@ -312,8 +295,6 @@ func (pc *PktConn) Write(b []byte) (int, error) {
 	copy(buf, pc.target)
 	copy(buf[len(pc.target):], b)
 
-	// logf("Write: \n%s", hex.Dump(buf))
-
 	return pc.PacketConn.WriteTo(buf, pc.addr)
 }
 

udptun.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"encoding/hex"
 	"net"
 	"time"
 )
@@ -45,9 +44,6 @@ func (s *UDPTun) ListenAndServe() {
 			continue
 		}
 
-		logf("ClientAddr: %s", clientAddr)
-		logf("ReadFrom:\n%s", hex.Dump(buf[:n]))
-
 		go func() {
 			rc, wt, err := s.sDialer.DialUDP("udp", s.raddr)
 			if err != nil {
@@ -55,15 +51,12 @@ func (s *UDPTun) ListenAndServe() {
 				return
 			}
 
-			logf("WriteTo")
 			n, err = rc.WriteTo(buf[:n], wt)
 			if err != nil {
 				logf("proxy-udptun rc.Write error: %v", err)
 				return
 			}
 
-			logf("ReadFrom")
-
 			rcBuf := make([]byte, udpBufSize)
 			rc.SetReadDeadline(time.Now().Add(time.Minute))
 
@@ -74,9 +67,6 @@ func (s *UDPTun) ListenAndServe() {
 			}
 			rc.Close()
 
-			// logf("rc resp: \n%s", hex.Dump(buf[:n]))
-
-			logf("c.WriteTo")
 			c.WriteTo(rcBuf[:n], clientAddr)
 			logf("proxy-udptun %s <-> %s", clientAddr, s.raddr)
 		}()