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// +build !confonly
package socks
import (
"encoding/binary"
"io"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/net"
"v2ray.com/core/common/protocol"
)
const (
socks5Version = 0x05
socks4Version = 0x04
cmdTCPConnect = 0x01
cmdTCPBind = 0x02
cmdUDPPort = 0x03
cmdTorResolve = 0xF0
cmdTorResolvePTR = 0xF1
socks4RequestGranted = 90
socks4RequestRejected = 91
authNotRequired = 0x00
//authGssAPI = 0x01
authPassword = 0x02
authNoMatchingMethod = 0xFF
statusSuccess = 0x00
statusCmdNotSupport = 0x07
)
var addrParser = protocol.NewAddressParser(
protocol.AddressFamilyByte(0x01, net.AddressFamilyIPv4),
protocol.AddressFamilyByte(0x04, net.AddressFamilyIPv6),
protocol.AddressFamilyByte(0x03, net.AddressFamilyDomain),
)
type ServerSession struct {
config *ServerConfig
port net.Port
}
func (s *ServerSession) handshake4(cmd byte, reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
if s.config.AuthType == AuthType_PASSWORD {
writeSocks4Response(writer, socks4RequestRejected, net.AnyIP, net.Port(0)) // nolint: errcheck
return nil, newError("socks 4 is not allowed when auth is required.")
}
var port net.Port
var address net.Address
{
buffer := buf.StackNew()
if _, err := buffer.ReadFullFrom(reader, 6); err != nil {
buffer.Release()
return nil, newError("insufficient header").Base(err)
}
port = net.PortFromBytes(buffer.BytesRange(0, 2))
address = net.IPAddress(buffer.BytesRange(2, 6))
buffer.Release()
}
if _, err := ReadUntilNull(reader); /* user id */ err != nil {
return nil, err
}
if address.IP()[0] == 0x00 {
domain, err := ReadUntilNull(reader)
if err != nil {
return nil, newError("failed to read domain for socks 4a").Base(err)
}
address = net.DomainAddress(domain)
}
switch cmd {
case cmdTCPConnect:
request := &protocol.RequestHeader{
Command: protocol.RequestCommandTCP,
Address: address,
Port: port,
Version: socks4Version,
}
if err := writeSocks4Response(writer, socks4RequestGranted, net.AnyIP, net.Port(0)); err != nil {
return nil, err
}
return request, nil
default:
writeSocks4Response(writer, socks4RequestRejected, net.AnyIP, net.Port(0)) // nolint: errcheck
return nil, newError("unsupported command: ", cmd)
}
}
func (s *ServerSession) auth5(nMethod byte, reader io.Reader, writer io.Writer) error {
buffer := buf.StackNew()
defer buffer.Release()
if _, err := buffer.ReadFullFrom(reader, int32(nMethod)); err != nil {
return newError("failed to read auth methods").Base(err)
}
var expectedAuth byte = authNotRequired
if s.config.AuthType == AuthType_PASSWORD {
expectedAuth = authPassword
}
if !hasAuthMethod(expectedAuth, buffer.BytesRange(0, int32(nMethod))) {
writeSocks5AuthenticationResponse(writer, socks5Version, authNoMatchingMethod) // nolint: errcheck
return newError("no matching auth method")
}
if err := writeSocks5AuthenticationResponse(writer, socks5Version, expectedAuth); err != nil {
return newError("failed to write auth response").Base(err)
}
if expectedAuth == authPassword {
username, password, err := ReadUsernamePassword(reader)
if err != nil {
return newError("failed to read username and password for authentication").Base(err)
}
if !s.config.HasAccount(username, password) {
writeSocks5AuthenticationResponse(writer, 0x01, 0xFF) // nolint: errcheck
return newError("invalid username or password")
}
if err := writeSocks5AuthenticationResponse(writer, 0x01, 0x00); err != nil {
return newError("failed to write auth response").Base(err)
}
}
return nil
}
func (s *ServerSession) handshake5(nMethod byte, reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
if err := s.auth5(nMethod, reader, writer); err != nil {
return nil, err
}
var cmd byte
{
buffer := buf.StackNew()
if _, err := buffer.ReadFullFrom(reader, 3); err != nil {
buffer.Release()
return nil, newError("failed to read request").Base(err)
}
cmd = buffer.Byte(1)
buffer.Release()
}
request := new(protocol.RequestHeader)
switch cmd {
case cmdTCPConnect, cmdTorResolve, cmdTorResolvePTR:
// We don't have a solution for Tor case now. Simply treat it as connect command.
request.Command = protocol.RequestCommandTCP
case cmdUDPPort:
if !s.config.UdpEnabled {
writeSocks5Response(writer, statusCmdNotSupport, net.AnyIP, net.Port(0)) // nolint: errcheck
return nil, newError("UDP is not enabled.")
}
request.Command = protocol.RequestCommandUDP
case cmdTCPBind:
writeSocks5Response(writer, statusCmdNotSupport, net.AnyIP, net.Port(0)) // nolint: errcheck
return nil, newError("TCP bind is not supported.")
default:
writeSocks5Response(writer, statusCmdNotSupport, net.AnyIP, net.Port(0)) // nolint: errcheck
return nil, newError("unknown command ", cmd)
}
request.Version = socks5Version
addr, port, err := addrParser.ReadAddressPort(nil, reader)
if err != nil {
return nil, newError("failed to read address").Base(err)
}
request.Address = addr
request.Port = port
responseAddress := net.AnyIP
responsePort := net.Port(1717)
if request.Command == protocol.RequestCommandUDP {
addr := s.config.Address.AsAddress()
if addr == nil {
addr = net.LocalHostIP
}
responseAddress = addr
responsePort = s.port
}
if err := writeSocks5Response(writer, statusSuccess, responseAddress, responsePort); err != nil {
return nil, err
}
return request, nil
}
// Handshake performs a Socks4/4a/5 handshake.
func (s *ServerSession) Handshake(reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
buffer := buf.StackNew()
if _, err := buffer.ReadFullFrom(reader, 2); err != nil {
buffer.Release()
return nil, newError("insufficient header").Base(err)
}
version := buffer.Byte(0)
cmd := buffer.Byte(1)
buffer.Release()
switch version {
case socks4Version:
return s.handshake4(cmd, reader, writer)
case socks5Version:
return s.handshake5(cmd, reader, writer)
default:
return nil, newError("unknown Socks version: ", version)
}
}
// ReadUsernamePassword reads Socks 5 username/password message from the given reader.
// +----+------+----------+------+----------+
// |VER | ULEN | UNAME | PLEN | PASSWD |
// +----+------+----------+------+----------+
// | 1 | 1 | 1 to 255 | 1 | 1 to 255 |
// +----+------+----------+------+----------+
func ReadUsernamePassword(reader io.Reader) (string, string, error) {
buffer := buf.StackNew()
defer buffer.Release()
if _, err := buffer.ReadFullFrom(reader, 2); err != nil {
return "", "", err
}
nUsername := int32(buffer.Byte(1))
buffer.Clear()
if _, err := buffer.ReadFullFrom(reader, nUsername); err != nil {
return "", "", err
}
username := buffer.String()
buffer.Clear()
if _, err := buffer.ReadFullFrom(reader, 1); err != nil {
return "", "", err
}
nPassword := int32(buffer.Byte(0))
buffer.Clear()
if _, err := buffer.ReadFullFrom(reader, nPassword); err != nil {
return "", "", err
}
password := buffer.String()
return username, password, nil
}
// ReadUntilNull reads content from given reader, until a null (0x00) byte.
func ReadUntilNull(reader io.Reader) (string, error) {
b := buf.StackNew()
defer b.Release()
for {
_, err := b.ReadFullFrom(reader, 1)
if err != nil {
return "", err
}
if b.Byte(b.Len()-1) == 0x00 {
b.Resize(0, b.Len()-1)
return b.String(), nil
}
if b.IsFull() {
return "", newError("buffer overrun")
}
}
}
func hasAuthMethod(expectedAuth byte, authCandidates []byte) bool {
for _, a := range authCandidates {
if a == expectedAuth {
return true
}
}
return false
}
func writeSocks5AuthenticationResponse(writer io.Writer, version byte, auth byte) error {
return buf.WriteAllBytes(writer, []byte{version, auth})
}
func writeSocks5Response(writer io.Writer, errCode byte, address net.Address, port net.Port) error {
buffer := buf.New()
defer buffer.Release()
common.Must2(buffer.Write([]byte{socks5Version, errCode, 0x00 /* reserved */}))
if err := addrParser.WriteAddressPort(buffer, address, port); err != nil {
return err
}
return buf.WriteAllBytes(writer, buffer.Bytes())
}
func writeSocks4Response(writer io.Writer, errCode byte, address net.Address, port net.Port) error {
buffer := buf.StackNew()
defer buffer.Release()
common.Must(buffer.WriteByte(0x00))
common.Must(buffer.WriteByte(errCode))
portBytes := buffer.Extend(2)
binary.BigEndian.PutUint16(portBytes, port.Value())
common.Must2(buffer.Write(address.IP()))
return buf.WriteAllBytes(writer, buffer.Bytes())
}
func DecodeUDPPacket(packet *buf.Buffer) (*protocol.RequestHeader, error) {
if packet.Len() < 5 {
return nil, newError("insufficient length of packet.")
}
request := &protocol.RequestHeader{
Version: socks5Version,
Command: protocol.RequestCommandUDP,
}
// packet[0] and packet[1] are reserved
if packet.Byte(2) != 0 /* fragments */ {
return nil, newError("discarding fragmented payload.")
}
packet.Advance(3)
addr, port, err := addrParser.ReadAddressPort(nil, packet)
if err != nil {
return nil, newError("failed to read UDP header").Base(err)
}
request.Address = addr
request.Port = port
return request, nil
}
func EncodeUDPPacket(request *protocol.RequestHeader, data []byte) (*buf.Buffer, error) {
b := buf.New()
common.Must2(b.Write([]byte{0, 0, 0 /* Fragment */}))
if err := addrParser.WriteAddressPort(b, request.Address, request.Port); err != nil {
b.Release()
return nil, err
}
common.Must2(b.Write(data))
return b, nil
}
type UDPReader struct {
reader io.Reader
}
func NewUDPReader(reader io.Reader) *UDPReader {
return &UDPReader{reader: reader}
}
func (r *UDPReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
b := buf.New()
if _, err := b.ReadFrom(r.reader); err != nil {
return nil, err
}
if _, err := DecodeUDPPacket(b); err != nil {
return nil, err
}
return buf.MultiBuffer{b}, nil
}
type UDPWriter struct {
request *protocol.RequestHeader
writer io.Writer
}
func NewUDPWriter(request *protocol.RequestHeader, writer io.Writer) *UDPWriter {
return &UDPWriter{
request: request,
writer: writer,
}
}
// Write implements io.Writer.
func (w *UDPWriter) Write(b []byte) (int, error) {
eb, err := EncodeUDPPacket(w.request, b)
if err != nil {
return 0, err
}
defer eb.Release()
if _, err := w.writer.Write(eb.Bytes()); err != nil {
return 0, err
}
return len(b), nil
}
func ClientHandshake(request *protocol.RequestHeader, reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
authByte := byte(authNotRequired)
if request.User != nil {
authByte = byte(authPassword)
}
b := buf.New()
defer b.Release()
common.Must2(b.Write([]byte{socks5Version, 0x01, authByte}))
if authByte == authPassword {
account := request.User.Account.(*Account)
common.Must(b.WriteByte(0x01))
common.Must(b.WriteByte(byte(len(account.Username))))
common.Must2(b.WriteString(account.Username))
common.Must(b.WriteByte(byte(len(account.Password))))
common.Must2(b.WriteString(account.Password))
}
if err := buf.WriteAllBytes(writer, b.Bytes()); err != nil {
return nil, err
}
b.Clear()
if _, err := b.ReadFullFrom(reader, 2); err != nil {
return nil, err
}
if b.Byte(0) != socks5Version {
return nil, newError("unexpected server version: ", b.Byte(0)).AtWarning()
}
if b.Byte(1) != authByte {
return nil, newError("auth method not supported.").AtWarning()
}
if authByte == authPassword {
b.Clear()
if _, err := b.ReadFullFrom(reader, 2); err != nil {
return nil, err
}
if b.Byte(1) != 0x00 {
return nil, newError("server rejects account: ", b.Byte(1))
}
}
b.Clear()
command := byte(cmdTCPConnect)
if request.Command == protocol.RequestCommandUDP {
command = byte(cmdUDPPort)
}
common.Must2(b.Write([]byte{socks5Version, command, 0x00 /* reserved */}))
if err := addrParser.WriteAddressPort(b, request.Address, request.Port); err != nil {
return nil, err
}
if err := buf.WriteAllBytes(writer, b.Bytes()); err != nil {
return nil, err
}
b.Clear()
if _, err := b.ReadFullFrom(reader, 3); err != nil {
return nil, err
}
resp := b.Byte(1)
if resp != 0x00 {
return nil, newError("server rejects request: ", resp)
}
b.Clear()
address, port, err := addrParser.ReadAddressPort(b, reader)
if err != nil {
return nil, err
}
if request.Command == protocol.RequestCommandUDP {
udpRequest := &protocol.RequestHeader{
Version: socks5Version,
Command: protocol.RequestCommandUDP,
Address: address,
Port: port,
}
return udpRequest, nil
}
return nil, nil
}
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