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508 lines
13 KiB
508 lines
13 KiB
package socks
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import (
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"io"
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"v2ray.com/core/common"
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"v2ray.com/core/common/buf"
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"v2ray.com/core/common/net"
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"v2ray.com/core/common/protocol"
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"v2ray.com/core/common/serial"
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)
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const (
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socks5Version = 0x05
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socks4Version = 0x04
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cmdTCPConnect = 0x01
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cmdTCPBind = 0x02
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cmdUDPPort = 0x03
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socks4RequestGranted = 90
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socks4RequestRejected = 91
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authNotRequired = 0x00
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//authGssAPI = 0x01
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authPassword = 0x02
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authNoMatchingMethod = 0xFF
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addrTypeIPv4 = 0x01
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addrTypeIPv6 = 0x04
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addrTypeDomain = 0x03
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statusSuccess = 0x00
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statusCmdNotSupport = 0x07
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)
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type ServerSession struct {
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config *ServerConfig
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port net.Port
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}
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func (s *ServerSession) Handshake(reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
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buffer := buf.NewLocal(512)
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request := new(protocol.RequestHeader)
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, 2)); err != nil {
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return nil, newError("insufficient header").Base(err)
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}
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version := buffer.Byte(0)
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if version == socks4Version {
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, 6)); err != nil {
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return nil, newError("insufficient header").Base(err)
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}
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port := net.PortFromBytes(buffer.BytesRange(2, 4))
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address := net.IPAddress(buffer.BytesRange(4, 8))
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_, err := readUntilNull(reader) // user id
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if err != nil {
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return nil, err
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}
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if address.IP()[0] == 0x00 {
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domain, err := readUntilNull(reader)
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if err != nil {
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return nil, newError("failed to read domain for socks 4a").Base(err)
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}
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address = net.DomainAddress(domain)
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}
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switch buffer.Byte(1) {
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case cmdTCPConnect:
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request.Command = protocol.RequestCommandTCP
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request.Address = address
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request.Port = port
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request.Version = socks4Version
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if err := writeSocks4Response(writer, socks4RequestGranted, net.AnyIP, net.Port(0)); err != nil {
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return nil, err
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}
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return request, nil
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default:
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writeSocks4Response(writer, socks4RequestRejected, net.AnyIP, net.Port(0))
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return nil, newError("unsupported command: ", buffer.Byte(1))
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}
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}
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if version == socks5Version {
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nMethod := int(buffer.Byte(1))
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, nMethod)); err != nil {
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return nil, newError("failed to read auth methods").Base(err)
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}
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var expectedAuth byte = authNotRequired
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if s.config.AuthType == AuthType_PASSWORD {
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expectedAuth = authPassword
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}
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if !hasAuthMethod(expectedAuth, buffer.BytesRange(2, 2+nMethod)) {
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writeSocks5AuthenticationResponse(writer, socks5Version, authNoMatchingMethod)
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return nil, newError("no matching auth method")
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}
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if err := writeSocks5AuthenticationResponse(writer, socks5Version, expectedAuth); err != nil {
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return nil, newError("failed to write auth response").Base(err)
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}
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if expectedAuth == authPassword {
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username, password, err := readUsernamePassword(reader)
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if err != nil {
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return nil, newError("failed to read username and password for authentication").Base(err)
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}
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if !s.config.HasAccount(username, password) {
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writeSocks5AuthenticationResponse(writer, 0x01, 0xFF)
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return nil, newError("invalid username or password")
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}
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if err := writeSocks5AuthenticationResponse(writer, 0x01, 0x00); err != nil {
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return nil, newError("failed to write auth response").Base(err)
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}
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}
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if err := buffer.Reset(buf.ReadFullFrom(reader, 4)); err != nil {
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return nil, newError("failed to read request").Base(err)
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}
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cmd := buffer.Byte(1)
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if cmd == cmdTCPBind || (cmd == cmdUDPPort && !s.config.UdpEnabled) {
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writeSocks5Response(writer, statusCmdNotSupport, net.AnyIP, net.Port(0))
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return nil, newError("unsupported command: ", cmd)
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}
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switch cmd {
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case cmdTCPConnect:
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request.Command = protocol.RequestCommandTCP
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case cmdUDPPort:
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request.Command = protocol.RequestCommandUDP
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}
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addrType := buffer.Byte(3)
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buffer.Clear()
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request.Version = socks5Version
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switch addrType {
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case addrTypeIPv4:
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, 4)); err != nil {
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return nil, err
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}
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request.Address = net.IPAddress(buffer.Bytes())
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case addrTypeIPv6:
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, 16)); err != nil {
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return nil, err
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}
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request.Address = net.IPAddress(buffer.Bytes())
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case addrTypeDomain:
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, 1)); err != nil {
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return nil, err
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}
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domainLength := int(buffer.Byte(0))
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, domainLength)); err != nil {
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return nil, err
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}
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request.Address = net.ParseAddress(string(buffer.BytesFrom(-domainLength)))
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default:
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return nil, newError("Unknown address type: ", addrType)
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}
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if err := buffer.AppendSupplier(buf.ReadFullFrom(reader, 2)); err != nil {
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return nil, err
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}
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request.Port = net.PortFromBytes(buffer.BytesFrom(-2))
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responseAddress := net.AnyIP
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responsePort := net.Port(1717)
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if request.Command == protocol.RequestCommandUDP {
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addr := s.config.Address.AsAddress()
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if addr == nil {
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addr = net.LocalHostIP
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}
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responseAddress = addr
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responsePort = s.port
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}
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if err := writeSocks5Response(writer, statusSuccess, responseAddress, responsePort); err != nil {
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return nil, err
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}
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return request, nil
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}
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return nil, newError("unknown Socks version: ", version)
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}
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func readUsernamePassword(reader io.Reader) (string, string, error) {
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buffer := buf.NewLocal(512)
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defer buffer.Release()
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if err := buffer.Reset(buf.ReadFullFrom(reader, 2)); err != nil {
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return "", "", err
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}
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nUsername := int(buffer.Byte(1))
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if err := buffer.Reset(buf.ReadFullFrom(reader, nUsername)); err != nil {
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return "", "", err
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}
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username := buffer.String()
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if err := buffer.Reset(buf.ReadFullFrom(reader, 1)); err != nil {
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return "", "", err
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}
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nPassword := int(buffer.Byte(0))
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if err := buffer.Reset(buf.ReadFullFrom(reader, nPassword)); err != nil {
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return "", "", err
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}
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password := buffer.String()
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return username, password, nil
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}
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func readUntilNull(reader io.Reader) (string, error) {
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var b [256]byte
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size := 0
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for {
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_, err := reader.Read(b[size : size+1])
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if err != nil {
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return "", err
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}
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if b[size] == 0x00 {
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return string(b[:size]), nil
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}
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size++
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if size == 256 {
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return "", newError("buffer overrun")
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}
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}
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}
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func hasAuthMethod(expectedAuth byte, authCandidates []byte) bool {
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for _, a := range authCandidates {
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if a == expectedAuth {
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return true
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}
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}
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return false
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}
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func writeSocks5AuthenticationResponse(writer io.Writer, version byte, auth byte) error {
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_, err := writer.Write([]byte{version, auth})
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return err
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}
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func appendAddress(buffer *buf.Buffer, address net.Address, port net.Port) error {
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switch address.Family() {
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case net.AddressFamilyIPv4:
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buffer.AppendBytes(0x01)
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buffer.Append(address.IP())
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case net.AddressFamilyIPv6:
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buffer.AppendBytes(0x04)
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buffer.Append(address.IP())
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case net.AddressFamilyDomain:
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if protocol.IsDomainTooLong(address.Domain()) {
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return newError("Super long domain is not supported in Socks protocol: ", address.Domain())
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}
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buffer.AppendBytes(0x03, byte(len(address.Domain())))
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common.Must(buffer.AppendSupplier(serial.WriteString(address.Domain())))
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}
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common.Must(buffer.AppendSupplier(serial.WriteUint16(port.Value())))
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return nil
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}
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func writeSocks5Response(writer io.Writer, errCode byte, address net.Address, port net.Port) error {
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buffer := buf.NewLocal(64)
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buffer.AppendBytes(socks5Version, errCode, 0x00 /* reserved */)
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if err := appendAddress(buffer, address, port); err != nil {
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return err
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}
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_, err := writer.Write(buffer.Bytes())
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return err
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}
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func writeSocks4Response(writer io.Writer, errCode byte, address net.Address, port net.Port) error {
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buffer := buf.NewLocal(32)
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buffer.AppendBytes(0x00, errCode)
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buffer.AppendSupplier(serial.WriteUint16(port.Value()))
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buffer.Append(address.IP())
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_, err := writer.Write(buffer.Bytes())
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return err
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}
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func DecodeUDPPacket(packet []byte) (*protocol.RequestHeader, []byte, error) {
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if len(packet) < 5 {
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return nil, nil, newError("insufficient length of packet.")
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}
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request := &protocol.RequestHeader{
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Version: socks5Version,
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Command: protocol.RequestCommandUDP,
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}
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// packet[0] and packet[1] are reserved
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if packet[2] != 0 /* fragments */ {
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return nil, nil, newError("discarding fragmented payload.")
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}
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addrType := packet[3]
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var dataBegin int
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switch addrType {
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case addrTypeIPv4:
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if len(packet) < 10 {
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return nil, nil, newError("insufficient length of packet")
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}
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ip := packet[4:8]
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request.Port = net.PortFromBytes(packet[8:10])
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request.Address = net.IPAddress(ip)
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dataBegin = 10
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case addrTypeIPv6:
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if len(packet) < 22 {
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return nil, nil, newError("insufficient length of packet")
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}
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ip := packet[4:20]
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request.Port = net.PortFromBytes(packet[20:22])
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request.Address = net.IPAddress(ip)
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dataBegin = 22
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case addrTypeDomain:
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domainLength := int(packet[4])
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if len(packet) < 5+domainLength+2 {
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return nil, nil, newError("insufficient length of packet")
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}
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domain := string(packet[5 : 5+domainLength])
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request.Port = net.PortFromBytes(packet[5+domainLength : 5+domainLength+2])
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request.Address = net.ParseAddress(domain)
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dataBegin = 5 + domainLength + 2
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default:
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return nil, nil, newError("unknown address type ", addrType)
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}
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return request, packet[dataBegin:], nil
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}
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func EncodeUDPPacket(request *protocol.RequestHeader, data []byte) (*buf.Buffer, error) {
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b := buf.New()
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b.AppendBytes(0, 0, 0 /* Fragment */)
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if err := appendAddress(b, request.Address, request.Port); err != nil {
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return nil, err
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}
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b.Append(data)
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return b, nil
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}
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type UDPReader struct {
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reader io.Reader
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}
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func NewUDPReader(reader io.Reader) *UDPReader {
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return &UDPReader{reader: reader}
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}
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func (r *UDPReader) Read() (buf.MultiBuffer, error) {
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b := buf.New()
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if err := b.AppendSupplier(buf.ReadFrom(r.reader)); err != nil {
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return nil, err
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}
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_, data, err := DecodeUDPPacket(b.Bytes())
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if err != nil {
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return nil, err
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}
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b.Clear()
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b.Append(data)
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return buf.NewMultiBufferValue(b), nil
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}
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type UDPWriter struct {
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request *protocol.RequestHeader
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writer io.Writer
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}
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func NewUDPWriter(request *protocol.RequestHeader, writer io.Writer) *UDPWriter {
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return &UDPWriter{
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request: request,
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writer: writer,
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}
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}
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// Write implements io.Writer.
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func (w *UDPWriter) Write(b []byte) (int, error) {
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eb, err := EncodeUDPPacket(w.request, b)
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if err != nil {
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return 0, err
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}
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defer eb.Release()
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if _, err := w.writer.Write(eb.Bytes()); err != nil {
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return 0, err
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}
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return len(b), nil
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}
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func ClientHandshake(request *protocol.RequestHeader, reader io.Reader, writer io.Writer) (*protocol.RequestHeader, error) {
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authByte := byte(authNotRequired)
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if request.User != nil {
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authByte = byte(authPassword)
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}
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authRequest := []byte{socks5Version, 0x01, authByte}
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if _, err := writer.Write(authRequest); err != nil {
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return nil, err
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}
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b := buf.NewLocal(512)
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 2)); err != nil {
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return nil, err
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}
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if b.Byte(0) != socks5Version {
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return nil, newError("unexpected server version: ", b.Byte(0)).AtWarning()
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}
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if b.Byte(1) != authByte {
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return nil, newError("auth method not supported.").AtWarning()
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}
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if authByte == authPassword {
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rawAccount, err := request.User.GetTypedAccount()
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if err != nil {
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return nil, err
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}
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account := rawAccount.(*Account)
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b.Clear()
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b.AppendBytes(socks5Version, byte(len(account.Username)))
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b.Append([]byte(account.Username))
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b.AppendBytes(byte(len(account.Password)))
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b.Append([]byte(account.Password))
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if _, err := writer.Write(b.Bytes()); err != nil {
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return nil, err
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}
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b.Clear()
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 2)); err != nil {
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return nil, err
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}
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if b.Byte(1) != 0x00 {
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return nil, newError("server rejects account: ", b.Byte(1))
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}
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}
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b.Clear()
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command := byte(cmdTCPConnect)
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if request.Command == protocol.RequestCommandUDP {
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command = byte(cmdUDPPort)
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}
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b.AppendBytes(socks5Version, command, 0x00 /* reserved */)
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appendAddress(b, request.Address, request.Port)
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if _, err := writer.Write(b.Bytes()); err != nil {
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return nil, err
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}
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b.Clear()
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 4)); err != nil {
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return nil, err
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}
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resp := b.Byte(1)
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if resp != 0x00 {
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return nil, newError("server rejects request: ", resp)
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}
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addrType := b.Byte(3)
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b.Clear()
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var address net.Address
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switch addrType {
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case addrTypeIPv4:
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 4)); err != nil {
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return nil, err
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}
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address = net.IPAddress(b.Bytes())
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case addrTypeIPv6:
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 16)); err != nil {
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return nil, err
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}
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address = net.IPAddress(b.Bytes())
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case addrTypeDomain:
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 1)); err != nil {
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return nil, err
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}
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domainLength := int(b.Byte(0))
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, domainLength)); err != nil {
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return nil, err
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}
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address = net.DomainAddress(string(b.BytesFrom(-domainLength)))
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default:
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return nil, newError("unknown address type: ", addrType)
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}
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if err := b.AppendSupplier(buf.ReadFullFrom(reader, 2)); err != nil {
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return nil, err
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}
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port := net.PortFromBytes(b.BytesFrom(-2))
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if request.Command == protocol.RequestCommandUDP {
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udpRequest := &protocol.RequestHeader{
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Version: socks5Version,
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Command: protocol.RequestCommandUDP,
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Address: address,
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Port: port,
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}
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return udpRequest, nil
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}
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return nil, nil
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}
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