add socks client support

client.go

@@ -0,0 +1,145 @@
+package socks
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net"
+)
+
+// Client is a net.Conn with socks5 support
+type Client struct {
+	net.Conn
+	// socks5 username
+	Username string
+	// socks5 password
+	Password      string
+	handshakeDone bool
+	connected     bool
+}
+
+func (sc *Client) handShake() error {
+	if sc.handshakeDone {
+		return nil
+	}
+
+	// password auth or none
+	if _, err := sc.Conn.Write([]byte{socks5Version, 0x02, 0x00, 0x02}); err != nil {
+		return err
+	}
+
+	buf := make([]byte, 2)
+	if _, err := io.ReadFull(sc.Conn, buf); err != nil {
+		return err
+	}
+
+	if buf[0] != socks5Version {
+		return fmt.Errorf("error socks version %s", buf[0])
+	}
+
+	if buf[1] != 0x00 && buf[1] != 0x02 {
+		return fmt.Errorf("server return with code %s", buf[1])
+	}
+
+	if buf[1] == 0x00 {
+		sc.handshakeDone = true
+		return nil
+	}
+
+	// password auth
+
+	buf = make([]byte, 3+len(sc.Username)+len(sc.Password))
+
+	buf[0] = 0x01                                       // auth protocol version
+	buf[1] = byte(len(sc.Username))                     // username length
+	copy(buf[2:], []byte(sc.Username))                  // username
+	buf[2+len(sc.Username)] = byte(len(sc.Password))    // password length
+	copy(buf[3+len(sc.Username):], []byte(sc.Password)) //password
+
+	if _, err := sc.Conn.Write(buf); err != nil {
+		return err
+	}
+
+	if _, err := sc.Conn.Read(buf[:2]); err != nil {
+		return err
+	}
+
+	if buf[0] != 0x01 {
+		return fmt.Errorf("unexpected auth protocol version %v", buf[0])
+	}
+
+	// password auth success
+	if buf[1] == 0x00 {
+		sc.handshakeDone = true
+		return nil
+	}
+
+	return fmt.Errorf("password rejected")
+}
+
+// Connect connects to socks5 server and handshake
+func (sc *Client) Connect(host string, port uint16) error {
+	if !sc.handshakeDone {
+		if err := sc.handShake(); err != nil {
+			return err
+		}
+	}
+
+	if sc.connected {
+		return nil
+	}
+
+	l := 4 + len(host) + 1 + 2
+	buf := make([]byte, l)
+	buf[0] = socks5Version
+	buf[1] = cmdConnect
+	buf[2] = 0x00
+	buf[3] = addrTypeDomain
+	buf[4] = byte(len(host))
+
+	copy(buf[5:5+len(host)], []byte(host))
+
+	binary.BigEndian.PutUint16(buf[l-2:l], port)
+
+	if _, err := sc.Conn.Write(buf); err != nil {
+		return err
+	}
+
+	buf1 := make([]byte, 128)
+
+	if _, err := io.ReadAtLeast(sc.Conn, buf1, 10); err != nil {
+		return err
+	}
+
+	if buf1[0] != socks5Version {
+		return fmt.Errorf("error socks version %d", buf1[0])
+	}
+
+	if buf1[1] != 0x00 {
+		return fmt.Errorf("server error code %d", buf1[1])
+	}
+
+	sc.connected = true
+	return nil
+}
+
+// Read read from the underlying connection
+func (sc *Client) Read(b []byte) (int, error) {
+	if !sc.connected {
+		return 0, fmt.Errorf("call connect first")
+	}
+	return sc.Conn.Read(b)
+}
+
+// Write write data to underlying connection
+func (sc *Client) Write(b []byte) (int, error) {
+	if !sc.connected {
+		return 0, fmt.Errorf("call connect first")
+	}
+	return sc.Conn.Write(b)
+}
+
+// Close close the underlying connection
+func (sc *Client) Close() error {
+	return sc.Conn.Close()
+}

socks.go

@@ -21,7 +21,13 @@ type dialFunc func(network, addr string) (net.Conn, error)
 // SocksConn present a client connection
 type SocksConn struct {
 	ClientConn net.Conn
-	Dial       dialFunc
+	// the function to dial to upstream server
+	// when nil, use net.Dial
+	Dial dialFunc
+	// username for socks5 server
+	Username string
+	// password
+	Password string
 }
 
 // Serve serve the client
@@ -42,7 +48,8 @@ func (s *SocksConn) Serve() {
 		s4 := socks4Conn{clientConn: s.ClientConn, dial: dial}
 		s4.Serve()
 	case socks5Version:
-		s5 := socks5Conn{clientConn: s.ClientConn, dial: dial}
+		s5 := socks5Conn{clientConn: s.ClientConn, dial: dial,
+			username: s.Username, password: s.Password}
 		s5.Serve()
 	default:
 		log.Printf("error version %d", buf[0])

socks5.go

@@ -46,9 +46,13 @@ byte |0   |  1   | 2  |   3    | 4 | .. | n-2 | n-1 | n |
 
 */
 
-var Socks5AuthRequired bool
+// Socks5AuthRequired means socks5 server need auth or not
 
 type socks5Conn struct {
+	// username
+	username string
+	// password
+	password string
 	//addr        string
 	clientConn net.Conn
 	serverConn net.Conn
@@ -84,14 +88,14 @@ func (s5 *socks5Conn) handshake() error {
 	l := int(buf[0]) + 1
 	if n < l {
 		// read remains data
-		if n1, err := io.ReadFull(s5.clientConn, buf[n:l]); err != nil {
+		n1, err := io.ReadFull(s5.clientConn, buf[n:l])
+		if err != nil {
 			return err
-		} else {
-			n += n1
 		}
+		n += n1
 	}
 
-	if !Socks5AuthRequired {
+	if s5.username == "" {
 		// no auth required
 		s5.clientConn.Write([]byte{0x05, 0x00})
 		return nil
@@ -135,10 +139,10 @@ func (s5 *socks5Conn) passwordAuth() error {
 		return errors.New("unsupported auth version")
 	}
 
-	username_len := int(buf[1])
+	usernameLen := int(buf[1])
 
 	p0 := 2
-	p1 := p0 + username_len
+	p1 := p0 + usernameLen
 
 	if n < p1 {
 		n1, err := s5.clientConn.Read(buf[n:])
@@ -149,10 +153,10 @@ func (s5 *socks5Conn) passwordAuth() error {
 	}
 
 	username := buf[p0:p1]
-	password_len := int(buf[p1])
+	passwordLen := int(buf[p1])
 
 	p3 := p1 + 1
-	p4 := p3 + password_len
+	p4 := p3 + passwordLen
 
 	if n < p4 {
 		n1, err := s5.clientConn.Read(buf[n:])
@@ -164,15 +168,17 @@ func (s5 *socks5Conn) passwordAuth() error {
 
 	password := buf[p3:p4]
 
-	log.Printf("get username: %s, password: %s", username, password)
+	// log.Printf("get username: %s, password: %s", username, password)
 
-	if string(username) == "" && string(password) == "" {
-		s5.clientConn.Write([]byte{0x01, 0x01})
-	} else {
+	if string(username) == s5.username && string(password) == s5.password {
 		s5.clientConn.Write([]byte{0x01, 0x00})
+		return nil
 	}
 
-	return nil
+	// auth failed
+	s5.clientConn.Write([]byte{0x01, 0x01})
+
+	return fmt.Errorf("wrong password")
 }
 
 func (s5 *socks5Conn) processRequest() error {

socks_test.go

@@ -0,0 +1,112 @@
+package socks
+
+import (
+	//"bytes"
+	//"fmt"
+	"errors"
+	"log"
+	"net"
+	"testing"
+)
+
+func TestSocks(t *testing.T) {
+	if err := testSocks(t, "u1", "p1", true); err != nil {
+		t.Error(err)
+	}
+	if err := testSocks(t, "", "", false); err != nil {
+		t.Error(err)
+	}
+	if err := testSocks(t, "u3", "p3", true); err != nil {
+		t.Error(err)
+	}
+
+	if err := testSocks(t, "u3", "p3", false); err != nil {
+		log.Println(err)
+	} else {
+		t.Error("password not active")
+	}
+
+	if err := testSocks(t, "u3", "", false); err != nil {
+		log.Println(err)
+	} else {
+		t.Error("password not active")
+	}
+}
+
+func testSocks(t *testing.T, user, pass string, auth bool) error {
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return err
+	}
+	defer l.Close()
+
+	l1, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return err
+	}
+	defer l1.Close()
+
+	addr := l.Addr().String()
+
+	addr1 := l1.Addr()
+
+	go func() {
+		conn, err := l.Accept()
+		if err != nil {
+			return
+		}
+		log.Printf("connected from %s", conn.RemoteAddr())
+		s := SocksConn{ClientConn: conn, Username: user, Password: pass}
+		s.Serve()
+	}()
+
+	go func() {
+		conn, err := l1.Accept()
+		if err != nil {
+			return
+		}
+		log.Printf("server 2 accept connection from %s", conn.RemoteAddr())
+		defer conn.Close()
+		buf := make([]byte, 512)
+		n, err := conn.Read(buf)
+		if err != nil {
+			return
+		}
+		conn.Write(buf[:n])
+	}()
+
+	c, err := net.Dial("tcp", addr)
+	if err != nil {
+		return err
+	}
+
+	defer c.Close()
+	var sc Client
+	if auth {
+		sc = Client{Conn: c, Username: user, Password: pass}
+	} else {
+		sc = Client{Conn: c}
+	}
+	if err = sc.Connect("localhost", uint16(addr1.(*net.TCPAddr).Port)); err != nil {
+		return err
+	}
+
+	log.Printf("connect success")
+
+	str := "hello1234"
+	buf := make([]byte, 512)
+
+	if _, err := sc.Write([]byte(str)); err != nil {
+		return err
+	}
+
+	n, err := sc.Read(buf)
+	if err != nil {
+		return err
+	}
+
+	if string(buf[:n]) != str {
+		return errors.New("socks test failed")
+	}
+	return nil
+}