add support for socks5 connector udp relay

connector/socks/v5/conn.go

@@ -1,6 +1,14 @@
 package v5
 
-import "net"
+import (
+	"bytes"
+	"net"
+	"time"
+
+	"github.com/go-gost/core/common/bufpool"
+	"github.com/go-gost/core/logger"
+	"github.com/go-gost/gosocks5"
+)
 
 type bindConn struct {
 	net.Conn
@@ -15,3 +23,103 @@ func (c *bindConn) LocalAddr() net.Addr {
 func (c *bindConn) RemoteAddr() net.Addr {
 	return c.remoteAddr
 }
+
+type udpRelayConn struct {
+	udpConn    *net.UDPConn
+	tcpConn    net.Conn
+	taddr      net.Addr
+	bufferSize int
+	logger     logger.Logger
+}
+
+func (c *udpRelayConn) ReadFrom(b []byte) (n int, addr net.Addr, err error) {
+	buf := bufpool.Get(c.bufferSize)
+	defer bufpool.Put(buf)
+
+	nn, err := c.udpConn.Read(*buf)
+	if err != nil {
+		return
+	}
+
+	socksAddr := gosocks5.Addr{}
+	header := gosocks5.UDPHeader{
+		Addr: &socksAddr,
+	}
+	dgram := gosocks5.UDPDatagram{
+		Header: &header,
+	}
+	_, err = dgram.ReadFrom(bytes.NewReader((*buf)[:nn]))
+	if err != nil {
+		return
+	}
+
+	n = copy(b, dgram.Data)
+	addr, err = net.ResolveUDPAddr("udp", header.Addr.String())
+
+	return
+}
+
+func (c *udpRelayConn) Read(b []byte) (n int, err error) {
+	n, _, err = c.ReadFrom(b)
+	return
+}
+
+func (c *udpRelayConn) WriteTo(b []byte, addr net.Addr) (n int, err error) {
+	socksAddr := gosocks5.Addr{}
+	if err = socksAddr.ParseFrom(addr.String()); err != nil {
+		return
+	}
+
+	header := gosocks5.UDPHeader{
+		Addr: &socksAddr,
+	}
+	dgram := gosocks5.UDPDatagram{
+		Header: &header,
+		Data:   b,
+	}
+
+	buf := bufpool.Get(c.bufferSize)
+	defer bufpool.Put(buf)
+
+	nn, err := dgram.WriteTo(bytes.NewBuffer((*buf)[:0]))
+	if err != nil {
+		return
+	}
+	if nn > int64(len(*buf)) {
+		nn = int64(len(*buf))
+	}
+
+	_, err = c.udpConn.Write((*buf)[:nn])
+	n = len(b)
+
+	return
+}
+
+func (c *udpRelayConn) Write(b []byte) (n int, err error) {
+	return c.WriteTo(b, c.taddr)
+}
+
+func (c *udpRelayConn) RemoteAddr() net.Addr {
+	return c.taddr
+}
+
+func (c *udpRelayConn) LocalAddr() net.Addr {
+	return c.udpConn.LocalAddr()
+}
+
+func (c *udpRelayConn) Close() error {
+	c.udpConn.Close()
+	return c.tcpConn.Close()
+}
+
+func (c *udpRelayConn) SetDeadline(t time.Time) error {
+	return c.udpConn.SetDeadline(t)
+}
+
+func (c *udpRelayConn) SetReadDeadline(t time.Time) error {
+	return c.udpConn.SetReadDeadline(t)
+}
+
+func (c *udpRelayConn) SetWriteDeadline(t time.Time) error {
+	return c.udpConn.SetWriteDeadline(t)
+}

connector/socks/v5/connector.go

@@ -151,6 +151,10 @@ func (c *socks5Connector) connectUDP(ctx context.Context, conn net.Conn, network
 		return nil, err
 	}
 
+	if c.md.relay == "udp" {
+		return c.relayUDP(ctx, conn, addr, log)
+	}
+
 	req := gosocks5.NewRequest(socks.CmdUDPTun, nil)
 	if err := req.Write(conn); err != nil {
 		log.Error(err)
@@ -171,3 +175,36 @@ func (c *socks5Connector) connectUDP(ctx context.Context, conn net.Conn, network
 
 	return socks.UDPTunClientConn(conn, addr), nil
 }
+
+func (c *socks5Connector) relayUDP(ctx context.Context, conn net.Conn, addr net.Addr, log logger.Logger) (net.Conn, error) {
+	req := gosocks5.NewRequest(gosocks5.CmdUdp, nil)
+	if err := req.Write(conn); err != nil {
+		log.Error(err)
+		return nil, err
+	}
+	log.Debug(req)
+
+	reply, err := gosocks5.ReadReply(conn)
+	if err != nil {
+		log.Error(err)
+		return nil, err
+	}
+	log.Debug(reply)
+
+	if reply.Rep != gosocks5.Succeeded {
+		return nil, errors.New("get socks5 UDP tunnel failure")
+	}
+
+	cc, err := (&net.Dialer{}).DialContext(ctx, "udp", reply.Addr.String())
+	if err != nil {
+		return nil, err
+	}
+
+	return &udpRelayConn{
+		udpConn:    cc.(*net.UDPConn),
+		tcpConn:    conn,
+		taddr:      addr,
+		bufferSize: c.md.udpBufferSize,
+		logger:     log,
+	}, nil
+}

connector/socks/v5/metadata.go

@@ -7,19 +7,32 @@ import (
 	mdx "github.com/go-gost/x/metadata"
 )
 
+const (
+	defaultUDPBufferSize = 4096
+)
+
 type metadata struct {
 	connectTimeout time.Duration
 	noTLS          bool
+	relay          string
+	udpBufferSize  int
 }
 
 func (c *socks5Connector) parseMetadata(md mdata.Metadata) (err error) {
 	const (
 		connectTimeout = "timeout"
 		noTLS          = "notls"
+		relay          = "relay"
+		udpBufferSize  = "udpBufferSize"
 	)
 
 	c.md.connectTimeout = mdx.GetDuration(md, connectTimeout)
 	c.md.noTLS = mdx.GetBool(md, noTLS)
+	c.md.relay = mdx.GetString(md, relay)
+	c.md.udpBufferSize = mdx.GetInt(md, udpBufferSize)
+	if c.md.udpBufferSize <= 0 {
+		c.md.udpBufferSize = defaultUDPBufferSize
+	}
 
 	return
 }