ss: add udp support as server mode

conn.go

@@ -52,3 +52,30 @@ func relay(left, right net.Conn) (int64, int64, error) {
 	}
 	return n, rs.N, err
 }
+
+// copy from src to dst at target with read timeout
+func timedCopy(dst net.PacketConn, target net.Addr, src net.PacketConn, timeout time.Duration, srcIncluded bool) error {
+	buf := make([]byte, udpBufSize)
+
+	for {
+		src.SetReadDeadline(time.Now().Add(timeout))
+		n, raddr, err := src.ReadFrom(buf)
+		if err != nil {
+			return err
+		}
+
+		if srcIncluded { // server -> client: add original packet source
+			srcAddr := ParseAddr(raddr.String())
+			copy(buf[len(srcAddr):], buf[:n])
+			copy(buf, srcAddr)
+			_, err = dst.WriteTo(buf[:len(srcAddr)+n], target)
+		} else { // client -> user: strip original packet source
+			srcAddr := SplitAddr(buf[:n])
+			_, err = dst.WriteTo(buf[len(srcAddr):n], target)
+		}
+
+		if err != nil {
+			return err
+		}
+	}
+}

socks5.go

@@ -326,7 +326,7 @@ func (s *SOCKS5) handshake(rw io.ReadWriter) (Addr, error) {
 func (a Addr) String() string {
 	var host, port string
 
-	switch a[0] { // address type
+	switch ATYP(a[0]) { // address type
 	case socks5Domain:
 		host = string(a[2 : 2+int(a[1])])
 		port = strconv.Itoa((int(a[2+int(a[1])]) << 8) | int(a[2+int(a[1])+1]))
@@ -341,6 +341,16 @@ func (a Addr) String() string {
 	return net.JoinHostPort(host, port)
 }
 
+// UoT udp over tcp
+func UoT(b byte) bool {
+	return b&0x8 == 0x8
+}
+
+// ATYP return the address type
+func ATYP(b byte) int {
+	return int(b &^ 0x8)
+}
+
 func readAddr(r io.Reader, b []byte) (Addr, error) {
 	if len(b) < MaxAddrLen {
 		return nil, io.ErrShortBuffer
@@ -350,7 +360,7 @@ func readAddr(r io.Reader, b []byte) (Addr, error) {
 		return nil, err
 	}
 
-	switch b[0] {
+	switch ATYP(b[0]) {
 	case socks5Domain:
 		_, err = io.ReadFull(r, b[1:2]) // read 2nd byte for domain length
 		if err != nil {
@@ -381,7 +391,7 @@ func SplitAddr(b []byte) Addr {
 		return nil
 	}
 
-	switch b[0] {
+	switch ATYP(b[0]) {
 	case socks5Domain:
 		if len(b) < 2 {
 			return nil

ss.go

@@ -5,16 +5,21 @@ import (
 	"log"
 	"net"
 	"strings"
+	"sync"
+	"time"
 
 	"github.com/shadowsocks/go-shadowsocks2/core"
+	"github.com/shadowsocks/go-shadowsocks2/socks"
 )
 
+const udpBufSize = 64 * 1024
+
 // SS .
 type SS struct {
 	*Forwarder
 	sDialer Dialer
 
-	core.StreamConnCipher
+	core.Cipher
 }
 
 // NewSS returns a shadowsocks proxy.
@@ -27,51 +32,57 @@ func NewSS(addr, method, pass string, cDialer Dialer, sDialer Dialer) (*SS, erro
 	s := &SS{
 		Forwarder: NewForwarder(addr, cDialer),
 		sDialer:   sDialer,
-		StreamConnCipher: ciph,
+		Cipher:    ciph,
 	}
 
 	return s, nil
 }
 
-// ListenAndServe shadowsocks requests as a server.
+// ListenAndServe serves ss requests.
 func (s *SS) ListenAndServe() {
+	go s.ListenAndServeUDP()
+	s.ListenAndServeTCP()
+}
+
+// ListenAndServeTCP serves tcp ss requests.
+func (s *SS) ListenAndServeTCP() {
 	l, err := net.Listen("tcp", s.addr)
 	if err != nil {
-		logf("failed to listen on %s: %v", s.addr, err)
+		logf("proxy-ss failed to listen on %s: %v", s.addr, err)
 		return
 	}
 
-	logf("listening TCP on %s", s.addr)
+	logf("proxy-ss listening TCP on %s", s.addr)
 
 	for {
 		c, err := l.Accept()
 		if err != nil {
-			logf("failed to accept: %v", err)
+			logf("proxy-ss failed to accept: %v", err)
 			continue
 		}
-		go s.Serve(c)
+		go s.ServeTCP(c)
 	}
 }
 
-// Serve .
-func (s *SS) Serve(c net.Conn) {
+// ServeTCP .
+func (s *SS) ServeTCP(c net.Conn) {
 	defer c.Close()
 
 	if c, ok := c.(*net.TCPConn); ok {
 		c.SetKeepAlive(true)
 	}
 
-	c = s.StreamConnCipher.StreamConn(c)
+	c = s.StreamConn(c)
 
 	tgt, err := ReadAddr(c)
 	if err != nil {
-		logf("failed to get target address: %v", err)
+		logf("proxy-ss failed to get target address: %v", err)
 		return
 	}
 
 	rc, err := s.sDialer.Dial("tcp", tgt.String())
 	if err != nil {
-		logf("failed to connect to target: %v", err)
+		logf("proxy-ss failed to connect to target: %v", err)
 		return
 	}
 	defer rc.Close()
@@ -88,6 +99,70 @@ func (s *SS) Serve(c net.Conn) {
 
 }
 
+// ListenAndServeUDP serves udp ss requests.
+func (s *SS) ListenAndServeUDP() {
+	c, err := net.ListenPacket("udp", s.addr)
+	if err != nil {
+		logf("proxy-ss failed to listen on %s: %v", s.addr, err)
+		return
+	}
+	defer c.Close()
+
+	logf("proxy-ss listening UDP on %s", s.addr)
+
+	c = s.PacketConn(c)
+
+	var nm sync.Map
+	buf := make([]byte, udpBufSize)
+
+	for {
+		n, raddr, err := c.ReadFrom(buf)
+		if err != nil {
+			logf("UDP remote read error: %v", err)
+			continue
+		}
+
+		tgtAddr := socks.SplitAddr(buf[:n])
+		if tgtAddr == nil {
+			logf("failed to split target address from packet: %q", buf[:n])
+			continue
+		}
+
+		tgtUDPAddr, err := net.ResolveUDPAddr("udp", tgtAddr.String())
+		if err != nil {
+			logf("failed to resolve target UDP address: %v", err)
+			continue
+		}
+
+		payload := buf[len(tgtAddr):n]
+
+		var pc net.PacketConn
+		v, _ := nm.Load(raddr.String())
+		if v == nil {
+			pc, err = net.ListenPacket("udp", "")
+			if err != nil {
+				logf("UDP remote listen error: %v", err)
+				continue
+			}
+
+			nm.Store(raddr.String(), pc)
+			go func() {
+				timedCopy(c, raddr, pc, 5*time.Minute, true)
+				pc.Close()
+				nm.Delete(raddr.String())
+			}()
+		}
+
+		pc = pc.(net.PacketConn)
+		_, err = pc.WriteTo(payload, tgtUDPAddr) // accept only UDPAddr despite the signature
+		if err != nil {
+			logf("UDP remote write error: %v", err)
+			continue
+		}
+
+	}
+}
+
 // Dial connects to the address addr on the network net via the proxy.
 func (s *SS) Dial(network, addr string) (net.Conn, error) {
 

tcptun.go

@@ -10,7 +10,7 @@ type TCPTun struct {
 	raddr string
 }
 
-// NewTCPTun returns a redirect proxy.
+// NewTCPTun returns a tcptun proxy.
 func NewTCPTun(addr, raddr string, sDialer Dialer) (*TCPTun, error) {
 	s := &TCPTun{
 		Forwarder: NewForwarder(addr, nil),