Add SOCKS4 support

io/socks/socks.go

@@ -3,19 +3,29 @@ package socks
 
 import (
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 
+	"github.com/v2ray/v2ray-core/log"
 	v2net "github.com/v2ray/v2ray-core/net"
 )
 
 const (
-	socksVersion = uint8(5)
+	socksVersion  = byte(0x05)
+	socks4Version = byte(0x04)
 
 	AuthNotRequired      = byte(0x00)
 	AuthGssApi           = byte(0x01)
 	AuthUserPass         = byte(0x02)
 	AuthNoMatchingMethod = byte(0xFF)
+
+	Socks4RequestGranted  = byte(90)
+	Socks4RequestRejected = byte(91)
+)
+
+var (
+	ErrorSocksVersion4 = errors.New("Using SOCKS version 4.")
 )
 
 // Authentication request header of Socks5 protocol
@@ -25,6 +35,13 @@ type Socks5AuthenticationRequest struct {
 	authMethods [256]byte
 }
 
+type Socks4AuthenticationRequest struct {
+	Version byte
+	Command byte
+	Port    uint16
+	IP      [4]byte
+}
+
 func (request *Socks5AuthenticationRequest) HasAuthMethod(method byte) bool {
 	for i := 0; i < int(request.nMethods); i++ {
 		if request.authMethods[i] == method {
@@ -34,10 +51,11 @@ func (request *Socks5AuthenticationRequest) HasAuthMethod(method byte) bool {
 	return false
 }
 
-func ReadAuthentication(reader io.Reader) (auth Socks5AuthenticationRequest, err error) {
+func ReadAuthentication(reader io.Reader) (auth Socks5AuthenticationRequest, auth4 Socks4AuthenticationRequest, err error) {
 	buffer := make([]byte, 256)
 	nBytes, err := reader.Read(buffer)
 	if err != nil {
+		log.Error("Failed to read socks authentication: %v", err)
 		return
 	}
 	if nBytes < 2 {
@@ -45,6 +63,15 @@ func ReadAuthentication(reader io.Reader) (auth Socks5AuthenticationRequest, err
 		return
 	}
 
+	if buffer[0] == socks4Version {
+		auth4.Version = buffer[0]
+		auth4.Command = buffer[1]
+		auth4.Port = binary.BigEndian.Uint16(buffer[2:4])
+		copy(auth4.IP[:], buffer[4:8])
+		err = ErrorSocksVersion4
+		return
+	}
+
 	auth.version = buffer[0]
 	if auth.version != socksVersion {
 		err = fmt.Errorf("Unknown SOCKS version %d", auth.version)
@@ -70,6 +97,12 @@ type Socks5AuthenticationResponse struct {
 	authMethod byte
 }
 
+type Socks4AuthenticationResponse struct {
+	result byte
+	port   uint16
+	ip     []byte
+}
+
 func NewAuthenticationResponse(authMethod byte) *Socks5AuthenticationResponse {
 	return &Socks5AuthenticationResponse{
 		version:    socksVersion,
@@ -77,11 +110,29 @@ func NewAuthenticationResponse(authMethod byte) *Socks5AuthenticationResponse {
 	}
 }
 
+func NewSocks4AuthenticationResponse(result byte, port uint16, ip []byte) *Socks4AuthenticationResponse {
+	return &Socks4AuthenticationResponse{
+		result: result,
+		port:   port,
+		ip:     ip,
+	}
+}
+
 func WriteAuthentication(writer io.Writer, r *Socks5AuthenticationResponse) error {
 	_, err := writer.Write([]byte{r.version, r.authMethod})
 	return err
 }
 
+func WriteSocks4AuthenticationResponse(writer io.Writer, r *Socks4AuthenticationResponse) error {
+	buffer := make([]byte, 8)
+	// buffer[0] is always 0
+	buffer[1] = r.result
+	binary.BigEndian.PutUint16(buffer[2:4], r.port)
+	copy(buffer[4:], r.ip)
+	_, err := writer.Write(buffer)
+	return err
+}
+
 type Socks5UserPassRequest struct {
 	version  byte
 	username string

io/socks/socks_test.go

@@ -30,13 +30,30 @@ func TestAuthenticationRequestRead(t *testing.T) {
 		0x01, // nMethods
 		0x02, // methods
 	}
-	request, err := ReadAuthentication(bytes.NewReader(rawRequest))
+	request, _, err := ReadAuthentication(bytes.NewReader(rawRequest))
 	assert.Error(err).IsNil()
 	assert.Byte(request.version).Named("Version").Equals(0x05)
 	assert.Byte(request.nMethods).Named("#Methods").Equals(0x01)
 	assert.Byte(request.authMethods[0]).Named("Auth Method").Equals(0x02)
 }
 
+func TestAuthentication4RequestRead(t *testing.T) {
+	assert := unit.Assert(t)
+
+	rawRequest := []byte{
+		0x04, // version
+		0x01, // command
+		0x00, 0x35,
+		0x72, 0x72, 0x72, 0x72,
+	}
+	_, request4, err := ReadAuthentication(bytes.NewReader(rawRequest))
+	assert.Error(err).Equals(ErrorSocksVersion4)
+	assert.Byte(request4.Version).Named("Version").Equals(0x04)
+	assert.Byte(request4.Command).Named("Command").Equals(0x01)
+	assert.Uint16(request4.Port).Named("Port").Equals(53)
+	assert.Bytes(request4.IP[:]).Named("IP").Equals([]byte{0x72, 0x72, 0x72, 0x72})
+}
+
 func TestAuthenticationResponseWrite(t *testing.T) {
 	assert := unit.Assert(t)
 

net/address.go

@@ -18,10 +18,12 @@ type Address struct {
 }
 
 func IPAddress(ip []byte, port uint16) Address {
+	ipCopy := make([]byte, 4)
+	copy(ipCopy, ip)
 	// TODO: check IP length
 	return Address{
 		Type:   AddrTypeIP,
-		IP:     net.IP(ip),
+		IP:     net.IP(ipCopy),
 		Domain: "",
 		Port:   port,
 	}

net/freedom/freedom.go

@@ -23,7 +23,7 @@ func (vconn *FreedomConnection) Start(ray core.OutboundRay) error {
 	output := ray.OutboundOutput()
 	conn, err := net.Dial("tcp", vconn.dest.String())
 	if err != nil {
-		return log.Error("Failed to open tcp: %s", vconn.dest.String())
+		return log.Error("Failed to open tcp: %s : %v", vconn.dest.String(), err)
 	}
 	log.Debug("Sending outbound tcp: %s", vconn.dest.String())
 

net/socks/socks.go

@@ -64,12 +64,29 @@ func (server *SocksServer) HandleConnection(connection net.Conn) error {
 
 	reader := bufio.NewReader(connection)
 
-	auth, err := socksio.ReadAuthentication(reader)
-	if err != nil {
+	auth, auth4, err := socksio.ReadAuthentication(reader)
+	if err != nil && err != socksio.ErrorSocksVersion4 {
 		log.Error("Error on reading authentication: %v", err)
 		return err
 	}
 
+	var dest v2net.Address
+
+	// TODO refactor this part
+	if err == socksio.ErrorSocksVersion4 {
+		result := socksio.Socks4RequestGranted
+		if auth4.Command == socksio.CmdBind {
+			result = socksio.Socks4RequestRejected
+		}
+		socks4Response := socksio.NewSocks4AuthenticationResponse(result, auth4.Port, auth4.IP[:])
+		socksio.WriteSocks4AuthenticationResponse(connection, socks4Response)
+
+		if result == socksio.Socks4RequestRejected {
+			return ErrorCommandNotSupported
+		}
+
+		dest = v2net.IPAddress(auth4.IP[:], auth4.Port)
+	} else {
 		expectedAuthMethod := socksio.AuthNotRequired
 		if server.config.AuthMethod == JsonAuthMethodUserPass {
 			expectedAuthMethod = socksio.AuthUserPass
@@ -149,7 +166,11 @@ func (server *SocksServer) HandleConnection(connection net.Conn) error {
 			log.Error("Error on socksio write response: %v", err)
 			return err
 		}
-	ray := server.vPoint.NewInboundConnectionAccepted(request.Destination())
+
+		dest = request.Destination()
+	}
+
+	ray := server.vPoint.NewInboundConnectionAccepted(dest)
 	input := ray.InboundInput()
 	output := ray.InboundOutput()
 	readFinish := make(chan bool)