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   1 # Public Domain SOCKS proxy protocol implementation
   2 # Adapted from https://gist.github.com/bluec0re/cafd3764412967417fd3
   3
   4 from __future__ import unicode_literals
   5
   6 # References:
   7 # SOCKS4 protocol http://www.openssh.com/txt/socks4.protocol
   8 # SOCKS4A protocol http://www.openssh.com/txt/socks4a.protocol
   9 # SOCKS5 protocol https://tools.ietf.org/html/rfc1928
  10 # SOCKS5 username/password authentication https://tools.ietf.org/html/rfc1929
  11
  12 import collections
  13 import socket
  14
  15 from .compat import (
  16     compat_ord,
  17     compat_struct_pack,
  18     compat_struct_unpack,
  19 )
  20
  21 __author__ = 'Timo Schmid <coding@timoschmid.de>'
  22
  23 SOCKS4_VERSION = 4
  24 SOCKS4_REPLY_VERSION = 0x00
  25 # Excerpt from SOCKS4A protocol:
  26 # if the client cannot resolve the destination host's domain name to find its
  27 # IP address, it should set the first three bytes of DSTIP to NULL and the last
  28 # byte to a non-zero value.
  29 SOCKS4_DEFAULT_DSTIP = compat_struct_pack('!BBBB', 0, 0, 0, 0xFF)
  30
  31 SOCKS5_VERSION = 5
  32 SOCKS5_USER_AUTH_VERSION = 0x01
  33 SOCKS5_USER_AUTH_SUCCESS = 0x00
  34
  35
  36 class Socks4Command(object):
  37     CMD_CONNECT = 0x01
  38     CMD_BIND = 0x02
  39
  40
  41 class Socks5Command(Socks4Command):
  42     CMD_UDP_ASSOCIATE = 0x03
  43
  44
  45 class Socks5Auth(object):
  46     AUTH_NONE = 0x00
  47     AUTH_GSSAPI = 0x01
  48     AUTH_USER_PASS = 0x02
  49     AUTH_NO_ACCEPTABLE = 0xFF  # For server response
  50
  51
  52 class Socks5AddressType(object):
  53     ATYP_IPV4 = 0x01
  54     ATYP_DOMAINNAME = 0x03
  55     ATYP_IPV6 = 0x04
  56
  57
  58 class ProxyError(IOError):
  59     ERR_SUCCESS = 0x00
  60
  61     def __init__(self, code=None, msg=None):
  62         if code is not None and msg is None:
  63             msg = self.CODES.get(code) and 'unknown error'
  64         super(ProxyError, self).__init__(code, msg)
  65
  66
  67 class InvalidVersionError(ProxyError):
  68     def __init__(self, expected_version, got_version):
  69         msg = ('Invalid response version from server. Expected {0:02x} got '
  70                '{1:02x}'.format(expected_version, got_version))
  71         super(InvalidVersionError, self).__init__(0, msg)
  72
  73
  74 class Socks4Error(ProxyError):
  75     ERR_SUCCESS = 90
  76
  77     CODES = {
  78         91: 'request rejected or failed',
  79         92: 'request rejected becasue SOCKS server cannot connect to identd on the client',
  80         93: 'request rejected because the client program and identd report different user-ids'
  81     }
  82
  83
  84 class Socks5Error(ProxyError):
  85     ERR_GENERAL_FAILURE = 0x01
  86
  87     CODES = {
  88         0x01: 'general SOCKS server failure',
  89         0x02: 'connection not allowed by ruleset',
  90         0x03: 'Network unreachable',
  91         0x04: 'Host unreachable',
  92         0x05: 'Connection refused',
  93         0x06: 'TTL expired',
  94         0x07: 'Command not supported',
  95         0x08: 'Address type not supported',
  96         0xFE: 'unknown username or invalid password',
  97         0xFF: 'all offered authentication methods were rejected'
  98     }
  99
 100
 101 class ProxyType(object):
 102     SOCKS4 = 0
 103     SOCKS4A = 1
 104     SOCKS5 = 2
 105
 106 Proxy = collections.namedtuple('Proxy', (
 107     'type', 'host', 'port', 'username', 'password', 'remote_dns'))
 108
 109
 110 class sockssocket(socket.socket):
 111     def __init__(self, *args, **kwargs):
 112         self._proxy = None
 113         super(sockssocket, self).__init__(*args, **kwargs)
 114
 115     def setproxy(self, proxytype, addr, port, rdns=True, username=None, password=None):
 116         assert proxytype in (ProxyType.SOCKS4, ProxyType.SOCKS4A, ProxyType.SOCKS5)
 117
 118         self._proxy = Proxy(proxytype, addr, port, username, password, rdns)
 119
 120     def recvall(self, cnt):
 121         data = b''
 122         while len(data) < cnt:
 123             cur = self.recv(cnt - len(data))
 124             if not cur:
 125                 raise IOError('{0} bytes missing'.format(cnt - len(data)))
 126             data += cur
 127         return data
 128
 129     def _recv_bytes(self, cnt):
 130         data = self.recvall(cnt)
 131         return compat_struct_unpack('!{0}B'.format(cnt), data)
 132
 133     @staticmethod
 134     def _len_and_data(data):
 135         return compat_struct_pack('!B', len(data)) + data
 136
 137     def _check_response_version(self, expected_version, got_version):
 138         if got_version != expected_version:
 139             self.close()
 140             raise InvalidVersionError(expected_version, got_version)
 141
 142     def _resolve_address(self, destaddr, default, use_remote_dns):
 143         try:
 144             return socket.inet_aton(destaddr)
 145         except socket.error:
 146             if use_remote_dns and self._proxy.remote_dns:
 147                 return default
 148             else:
 149                 return socket.inet_aton(socket.gethostbyname(destaddr))
 150
 151     def _setup_socks4(self, address, is_4a=False):
 152         destaddr, port = address
 153
 154         ipaddr = self._resolve_address(destaddr, SOCKS4_DEFAULT_DSTIP, use_remote_dns=is_4a)
 155
 156         packet = compat_struct_pack('!BBH', SOCKS4_VERSION, Socks4Command.CMD_CONNECT, port) + ipaddr
 157
 158         username = (self._proxy.username or '').encode('utf-8')
 159         packet += username + b'\x00'
 160
 161         if is_4a and self._proxy.remote_dns:
 162             packet += destaddr.encode('utf-8') + b'\x00'
 163
 164         self.sendall(packet)
 165
 166         version, resp_code, dstport, dsthost = compat_struct_unpack('!BBHI', self.recvall(8))
 167
 168         self._check_response_version(SOCKS4_REPLY_VERSION, version)
 169
 170         if resp_code != Socks4Error.ERR_SUCCESS:
 171             self.close()
 172             raise Socks4Error(resp_code)
 173
 174         return (dsthost, dstport)
 175
 176     def _setup_socks4a(self, address):
 177         self._setup_socks4(address, is_4a=True)
 178
 179     def _socks5_auth(self):
 180         packet = compat_struct_pack('!B', SOCKS5_VERSION)
 181
 182         auth_methods = [Socks5Auth.AUTH_NONE]
 183         if self._proxy.username and self._proxy.password:
 184             auth_methods.append(Socks5Auth.AUTH_USER_PASS)
 185
 186         packet += compat_struct_pack('!B', len(auth_methods))
 187         packet += compat_struct_pack('!{0}B'.format(len(auth_methods)), *auth_methods)
 188
 189         self.sendall(packet)
 190
 191         version, method = self._recv_bytes(2)
 192
 193         self._check_response_version(SOCKS5_VERSION, version)
 194
 195         if method == Socks5Auth.AUTH_NO_ACCEPTABLE:
 196             self.close()
 197             raise Socks5Error(method)
 198
 199         if method == Socks5Auth.AUTH_USER_PASS:
 200             username = self._proxy.username.encode('utf-8')
 201             password = self._proxy.password.encode('utf-8')
 202             packet = compat_struct_pack('!B', SOCKS5_USER_AUTH_VERSION)
 203             packet += self._len_and_data(username) + self._len_and_data(password)
 204             self.sendall(packet)
 205
 206             version, status = self._recv_bytes(2)
 207
 208             self._check_response_version(SOCKS5_USER_AUTH_VERSION, version)
 209
 210             if status != SOCKS5_USER_AUTH_SUCCESS:
 211                 self.close()
 212                 raise Socks5Error(Socks5Error.ERR_GENERAL_FAILURE)
 213
 214     def _setup_socks5(self, address):
 215         destaddr, port = address
 216
 217         ipaddr = self._resolve_address(destaddr, None, use_remote_dns=True)
 218
 219         self._socks5_auth()
 220
 221         reserved = 0
 222         packet = compat_struct_pack('!BBB', SOCKS5_VERSION, Socks5Command.CMD_CONNECT, reserved)
 223         if ipaddr is None:
 224             destaddr = destaddr.encode('utf-8')
 225             packet += compat_struct_pack('!B', Socks5AddressType.ATYP_DOMAINNAME)
 226             packet += self._len_and_data(destaddr)
 227         else:
 228             packet += compat_struct_pack('!B', Socks5AddressType.ATYP_IPV4) + ipaddr
 229         packet += compat_struct_pack('!H', port)
 230
 231         self.sendall(packet)
 232
 233         version, status, reserved, atype = self._recv_bytes(4)
 234
 235         self._check_response_version(SOCKS5_VERSION, version)
 236
 237         if status != Socks5Error.ERR_SUCCESS:
 238             self.close()
 239             raise Socks5Error(status)
 240
 241         if atype == Socks5AddressType.ATYP_IPV4:
 242             destaddr = self.recvall(4)
 243         elif atype == Socks5AddressType.ATYP_DOMAINNAME:
 244             alen = compat_ord(self.recv(1))
 245             destaddr = self.recvall(alen)
 246         elif atype == Socks5AddressType.ATYP_IPV6:
 247             destaddr = self.recvall(16)
 248         destport = compat_struct_unpack('!H', self.recvall(2))[0]
 249
 250         return (destaddr, destport)
 251
 252     def _make_proxy(self, connect_func, address):
 253         if not self._proxy:
 254             return connect_func(self, address)
 255
 256         result = connect_func(self, (self._proxy.host, self._proxy.port))
 257         if result != 0 and result is not None:
 258             return result
 259         setup_funcs = {
 260             ProxyType.SOCKS4: self._setup_socks4,
 261             ProxyType.SOCKS4A: self._setup_socks4a,
 262             ProxyType.SOCKS5: self._setup_socks5,
 263         }
 264         setup_funcs[self._proxy.type](address)
 265         return result
 266
 267     def connect(self, address):
 268         self._make_proxy(socket.socket.connect, address)
 269
 270     def connect_ex(self, address):
 271         return self._make_proxy(socket.socket.connect_ex, address)