package socks import ( "io" "v2ray.com/core/common" "v2ray.com/core/common/buf" "v2ray.com/core/common/net" "v2ray.com/core/common/protocol" "v2ray.com/core/common/vio" ) 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) Handshake(reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) { buffer := buf.New() defer buffer.Release() request := new(protocol.RequestHeader) if _, err := buffer.ReadFullFrom(reader, 2); err != nil { return nil, newError("insufficient header").Base(err) } version := buffer.Byte(0) if version == socks4Version { 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.") } if _, err := buffer.ReadFullFrom(reader, 6); err != nil { return nil, newError("insufficient header").Base(err) } port := net.PortFromBytes(buffer.BytesRange(2, 4)) address := net.IPAddress(buffer.BytesRange(4, 8)) 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 buffer.Byte(1) { case cmdTCPConnect: request.Command = protocol.RequestCommandTCP request.Address = address request.Port = port request.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: ", buffer.Byte(1)) } } if version == socks5Version { nMethod := int32(buffer.Byte(1)) if _, err := buffer.ReadFullFrom(reader, nMethod); err != nil { return nil, 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(2, 2+nMethod)) { writeSocks5AuthenticationResponse(writer, socks5Version, authNoMatchingMethod) // nolint: errcheck return nil, newError("no matching auth method") } if err := writeSocks5AuthenticationResponse(writer, socks5Version, expectedAuth); err != nil { return nil, newError("failed to write auth response").Base(err) } if expectedAuth == authPassword { username, password, err := readUsernamePassword(reader) if err != nil { return nil, newError("failed to read username and password for authentication").Base(err) } if !s.config.HasAccount(username, password) { writeSocks5AuthenticationResponse(writer, 0x01, 0xFF) // nolint: errcheck return nil, newError("invalid username or password") } if err := writeSocks5AuthenticationResponse(writer, 0x01, 0x00); err != nil { return nil, newError("failed to write auth response").Base(err) } } buffer.Clear() if _, err := buffer.ReadFullFrom(reader, 3); err != nil { return nil, newError("failed to read request").Base(err) } cmd := buffer.Byte(1) 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) } buffer.Clear() request.Version = socks5Version addr, port, err := addrParser.ReadAddressPort(buffer, 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 } return nil, newError("unknown Socks version: ", version) } func readUsernamePassword(reader io.Reader) (string, string, error) { buffer := buf.New() 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 } func readUntilNull(reader io.Reader) (string, error) { var b [256]byte size := 0 for { _, err := reader.Read(b[size : size+1]) if err != nil { return "", err } if b[size] == 0x00 { return string(b[:size]), nil } size++ if size == 256 { 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.WriteBytes(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.New() defer buffer.Release() common.Must2(buffer.WriteBytes(0x00, errCode)) common.Must2(vio.WriteUint16(buffer, 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.WriteBytes(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.NewMultiBufferValue(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.WriteBytes(socks5Version, 0x01, authByte)) if authByte == authPassword { account := request.User.Account.(*Account) common.Must2(b.WriteBytes(0x01, byte(len(account.Username)))) common.Must2(b.Write([]byte(account.Username))) common.Must2(b.WriteBytes(byte(len(account.Password)))) common.Must2(b.Write([]byte(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.WriteBytes(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 }