440 lines
15 KiB
Python
440 lines
15 KiB
Python
# Copyright (c) 2018, Neil Booth
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#
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# All rights reserved.
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#
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# The MIT License (MIT)
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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'''SOCKS proxying.'''
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import sys
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import asyncio
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import collections
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import ipaddress
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import socket
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import struct
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from functools import partial
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__all__ = ('SOCKSUserAuth', 'SOCKS4', 'SOCKS4a', 'SOCKS5', 'SOCKSProxy',
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'SOCKSError', 'SOCKSProtocolError', 'SOCKSFailure')
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SOCKSUserAuth = collections.namedtuple("SOCKSUserAuth", "username password")
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class SOCKSError(Exception):
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'''Base class for SOCKS exceptions. Each raised exception will be
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an instance of a derived class.'''
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class SOCKSProtocolError(SOCKSError):
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'''Raised when the proxy does not follow the SOCKS protocol'''
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class SOCKSFailure(SOCKSError):
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'''Raised when the proxy refuses or fails to make a connection'''
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class NeedData(Exception):
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pass
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class SOCKSBase(object):
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@classmethod
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def name(cls):
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return cls.__name__
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def __init__(self):
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self._buffer = bytes()
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self._state = self._start
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def _read(self, size):
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if len(self._buffer) < size:
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raise NeedData(size - len(self._buffer))
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result = self._buffer[:size]
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self._buffer = self._buffer[size:]
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return result
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def receive_data(self, data):
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self._buffer += data
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def next_message(self):
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return self._state()
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class SOCKS4(SOCKSBase):
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'''SOCKS4 protocol wrapper.'''
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# See http://ftp.icm.edu.pl/packages/socks/socks4/SOCKS4.protocol
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REPLY_CODES = {
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90: 'request granted',
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91: 'request rejected or failed',
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92: ('request rejected because SOCKS server cannot connect '
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'to identd on the client'),
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93: ('request rejected because the client program and identd '
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'report different user-ids')
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}
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def __init__(self, dst_host, dst_port, auth):
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super().__init__()
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self._dst_host = self._check_host(dst_host)
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self._dst_port = dst_port
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self._auth = auth
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@classmethod
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def _check_host(cls, host):
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if not isinstance(host, ipaddress.IPv4Address):
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try:
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host = ipaddress.IPv4Address(host)
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except ValueError:
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raise SOCKSProtocolError(
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f'SOCKS4 requires an IPv4 address: {host}') from None
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return host
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def _start(self):
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self._state = self._first_response
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if isinstance(self._dst_host, ipaddress.IPv4Address):
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# SOCKS4
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dst_ip_packed = self._dst_host.packed
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host_bytes = b''
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else:
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# SOCKS4a
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dst_ip_packed = b'\0\0\0\1'
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host_bytes = self._dst_host.encode() + b'\0'
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if isinstance(self._auth, SOCKSUserAuth):
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user_id = self._auth.username.encode()
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else:
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user_id = b''
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# Send TCP/IP stream CONNECT request
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return b''.join([b'\4\1', struct.pack('>H', self._dst_port),
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dst_ip_packed, user_id, b'\0', host_bytes])
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def _first_response(self):
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# Wait for 8-byte response
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data = self._read(8)
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if data[0] != 0:
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raise SOCKSProtocolError(f'invalid {self.name()} proxy '
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f'response: {data}')
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reply_code = data[1]
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if reply_code != 90:
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msg = self.REPLY_CODES.get(
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reply_code, f'unknown {self.name()} reply code {reply_code}')
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raise SOCKSFailure(f'{self.name()} proxy request failed: {msg}')
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# Other fields ignored
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return None
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class SOCKS4a(SOCKS4):
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@classmethod
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def _check_host(cls, host):
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if not isinstance(host, (str, ipaddress.IPv4Address)):
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raise SOCKSProtocolError(
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f'SOCKS4a requires an IPv4 address or host name: {host}')
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return host
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class SOCKS5(SOCKSBase):
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'''SOCKS protocol wrapper.'''
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# See https://tools.ietf.org/html/rfc1928
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ERROR_CODES = {
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1: 'general SOCKS server failure',
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2: 'connection not allowed by ruleset',
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3: 'network unreachable',
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4: 'host unreachable',
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5: 'connection refused',
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6: 'TTL expired',
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7: 'command not supported',
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8: 'address type not supported',
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}
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def __init__(self, dst_host, dst_port, auth):
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super().__init__()
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self._dst_bytes = self._destination_bytes(dst_host, dst_port)
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self._auth_bytes, self._auth_methods = self._authentication(auth)
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def _destination_bytes(self, host, port):
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if isinstance(host, ipaddress.IPv4Address):
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addr_bytes = b'\1' + host.packed
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elif isinstance(host, ipaddress.IPv6Address):
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addr_bytes = b'\4' + host.packed
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elif isinstance(host, str):
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host = host.encode()
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if len(host) > 255:
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raise SOCKSProtocolError(f'hostname too long: '
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f'{len(host)} bytes')
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addr_bytes = b'\3' + bytes([len(host)]) + host
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else:
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raise SOCKSProtocolError(f'SOCKS5 requires an IPv4 address, IPv6 '
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f'address, or host name: {host}')
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return addr_bytes + struct.pack('>H', port)
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def _authentication(self, auth):
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if isinstance(auth, SOCKSUserAuth):
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user_bytes = auth.username.encode()
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if not 0 < len(user_bytes) < 256:
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raise SOCKSProtocolError(f'username {auth.username} has '
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f'invalid length {len(user_bytes)}')
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pwd_bytes = auth.password.encode()
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if not 0 < len(pwd_bytes) < 256:
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raise SOCKSProtocolError(f'password has invalid length '
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f'{len(pwd_bytes)}')
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return b''.join([bytes([1, len(user_bytes)]), user_bytes,
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bytes([len(pwd_bytes)]), pwd_bytes]), [0, 2]
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return b'', [0]
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def _start(self):
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self._state = self._first_response
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return (b'\5' + bytes([len(self._auth_methods)])
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+ bytes(m for m in self._auth_methods))
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def _first_response(self):
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# Wait for 2-byte response
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data = self._read(2)
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if data[0] != 5:
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raise SOCKSProtocolError(f'invalid SOCKS5 proxy response: {data}')
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if data[1] not in self._auth_methods:
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raise SOCKSFailure('SOCKS5 proxy rejected authentication methods')
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# Authenticate if user-password authentication
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if data[1] == 2:
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self._state = self._auth_response
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return self._auth_bytes
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return self._request_connection()
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def _auth_response(self):
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data = self._read(2)
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if data[0] != 1:
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raise SOCKSProtocolError(f'invalid SOCKS5 proxy auth '
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f'response: {data}')
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if data[1] != 0:
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raise SOCKSFailure(f'SOCKS5 proxy auth failure code: '
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f'{data[1]}')
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return self._request_connection()
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def _request_connection(self):
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# Send connection request
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self._state = self._connect_response
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return b'\5\1\0' + self._dst_bytes
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def _connect_response(self):
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data = self._read(5)
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if data[0] != 5 or data[2] != 0 or data[3] not in (1, 3, 4):
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raise SOCKSProtocolError(f'invalid SOCKS5 proxy response: {data}')
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if data[1] != 0:
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raise SOCKSFailure(self.ERROR_CODES.get(
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data[1], f'unknown SOCKS5 error code: {data[1]}'))
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if data[3] == 1:
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addr_len = 3 # IPv4
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elif data[3] == 3:
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addr_len = data[4] # Hostname
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else:
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addr_len = 15 # IPv6
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self._state = partial(self._connect_response_rest, addr_len)
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return self.next_message()
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def _connect_response_rest(self, addr_len):
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self._read(addr_len + 2)
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return None
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class SOCKSProxy(object):
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def __init__(self, address, protocol, auth):
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'''A SOCKS proxy at an address following a SOCKS protocol. auth is an
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authentication method to use when connecting, or None.
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address is a (host, port) pair; for IPv6 it can instead be a
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(host, port, flowinfo, scopeid) 4-tuple.
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'''
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self.address = address
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self.protocol = protocol
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self.auth = auth
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# Set on each successful connection via the proxy to the
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# result of socket.getpeername()
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self.peername = None
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def __str__(self):
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auth = 'username' if self.auth else 'none'
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return f'{self.protocol.name()} proxy at {self.address}, auth: {auth}'
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async def _handshake(self, client, sock, loop):
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while True:
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count = 0
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try:
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message = client.next_message()
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except NeedData as e:
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count = e.args[0]
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else:
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if message is None:
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return
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await loop.sock_sendall(sock, message)
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if count:
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data = await loop.sock_recv(sock, count)
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if not data:
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raise SOCKSProtocolError("EOF received")
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client.receive_data(data)
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async def _connect_one(self, host, port):
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'''Connect to the proxy and perform a handshake requesting a
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connection to (host, port).
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Return the open socket on success, or the exception on failure.
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'''
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client = self.protocol(host, port, self.auth)
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sock = socket.socket()
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loop = asyncio.get_event_loop()
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try:
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# A non-blocking socket is required by loop socket methods
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sock.setblocking(False)
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await loop.sock_connect(sock, self.address)
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await self._handshake(client, sock, loop)
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self.peername = sock.getpeername()
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return sock
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except Exception as e:
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# Don't close - see https://github.com/kyuupichan/aiorpcX/issues/8
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if sys.platform.startswith('linux'):
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sock.close()
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return e
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async def _connect(self, addresses):
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'''Connect to the proxy and perform a handshake requesting a
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connection to each address in addresses.
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Return an (open_socket, address) pair on success.
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'''
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assert len(addresses) > 0
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exceptions = []
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for address in addresses:
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host, port = address[:2]
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sock = await self._connect_one(host, port)
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if isinstance(sock, socket.socket):
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return sock, address
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exceptions.append(sock)
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strings = set(f'{exc!r}' for exc in exceptions)
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raise (exceptions[0] if len(strings) == 1 else
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OSError(f'multiple exceptions: {", ".join(strings)}'))
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async def _detect_proxy(self):
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'''Return True if it appears we can connect to a SOCKS proxy,
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otherwise False.
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'''
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if self.protocol is SOCKS4a:
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host, port = 'www.apple.com', 80
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else:
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host, port = ipaddress.IPv4Address('8.8.8.8'), 53
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sock = await self._connect_one(host, port)
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if isinstance(sock, socket.socket):
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sock.close()
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return True
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# SOCKSFailure indicates something failed, but that we are
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# likely talking to a proxy
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return isinstance(sock, SOCKSFailure)
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@classmethod
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async def auto_detect_address(cls, address, auth):
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'''Try to detect a SOCKS proxy at address using the authentication
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method (or None). SOCKS5, SOCKS4a and SOCKS are tried in
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order. If a SOCKS proxy is detected a SOCKSProxy object is
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returned.
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Returning a SOCKSProxy does not mean it is functioning - for
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example, it may have no network connectivity.
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If no proxy is detected return None.
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'''
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for protocol in (SOCKS5, SOCKS4a, SOCKS4):
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proxy = cls(address, protocol, auth)
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if await proxy._detect_proxy():
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return proxy
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return None
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@classmethod
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async def auto_detect_host(cls, host, ports, auth):
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'''Try to detect a SOCKS proxy on a host on one of the ports.
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Calls auto_detect for the ports in order. Returns SOCKS are
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tried in order; a SOCKSProxy object for the first detected
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proxy is returned.
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Returning a SOCKSProxy does not mean it is functioning - for
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example, it may have no network connectivity.
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If no proxy is detected return None.
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'''
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for port in ports:
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address = (host, port)
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proxy = await cls.auto_detect_address(address, auth)
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if proxy:
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return proxy
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return None
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async def create_connection(self, protocol_factory, host, port, *,
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resolve=False, ssl=None,
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family=0, proto=0, flags=0):
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'''Set up a connection to (host, port) through the proxy.
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If resolve is True then host is resolved locally with
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getaddrinfo using family, proto and flags, otherwise the proxy
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is asked to resolve host.
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The function signature is similar to loop.create_connection()
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with the same result. The attribute _address is set on the
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protocol to the address of the successful remote connection.
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Additionally raises SOCKSError if something goes wrong with
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the proxy handshake.
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'''
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loop = asyncio.get_event_loop()
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if resolve:
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infos = await loop.getaddrinfo(host, port, family=family,
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type=socket.SOCK_STREAM,
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proto=proto, flags=flags)
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addresses = [info[4] for info in infos]
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else:
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addresses = [(host, port)]
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sock, address = await self._connect(addresses)
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def set_address():
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protocol = protocol_factory()
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protocol._address = address
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return protocol
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return await loop.create_connection(
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set_address, sock=sock, ssl=ssl,
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server_hostname=host if ssl else None)
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