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|
import enum
import ipaddress
import socket
from typing import Optional, Union
from dataclasses import dataclass, field
from .errors import ReplyError
from .._helpers import is_ip_address
RSV = NULL = AUTH_GRANTED = 0x00
SOCKS_VER = 0x05
class AuthMethod(enum.IntEnum):
ANONYMOUS = 0x00
GSSAPI = 0x01
USERNAME_PASSWORD = 0x02
NO_ACCEPTABLE = 0xFF
class AddressType(enum.IntEnum):
IPV4 = 0x01
DOMAIN = 0x03
IPV6 = 0x04
@classmethod
def from_ip_ver(cls, ver: int):
if ver == 4:
return cls.IPV4
if ver == 6:
return cls.IPV6
raise ValueError('Invalid IP version')
class Command(enum.IntEnum):
CONNECT = 0x01
BIND = 0x02
UDP_ASSOCIATE = 0x03
class ReplyCode(enum.IntEnum):
SUCCEEDED = 0x00
GENERAL_FAILURE = 0x01
CONNECTION_NOT_ALLOWED = 0x02
NETWORK_UNREACHABLE = 0x03
HOST_UNREACHABLE = 0x04
CONNECTION_REFUSED = 0x05
TTL_EXPIRED = 0x06
COMMAND_NOT_SUPPORTED = 0x07
ADDRESS_TYPE_NOT_SUPPORTED = 0x08
ReplyMessages = {
ReplyCode.SUCCEEDED: 'Request granted',
ReplyCode.GENERAL_FAILURE: 'General SOCKS server failure',
ReplyCode.CONNECTION_NOT_ALLOWED: 'Connection not allowed by ruleset',
ReplyCode.NETWORK_UNREACHABLE: 'Network unreachable',
ReplyCode.HOST_UNREACHABLE: 'Host unreachable',
ReplyCode.CONNECTION_REFUSED: 'Connection refused by destination host',
ReplyCode.TTL_EXPIRED: 'TTL expired',
ReplyCode.COMMAND_NOT_SUPPORTED: 'Command not supported or protocol error',
ReplyCode.ADDRESS_TYPE_NOT_SUPPORTED: 'Address type not supported',
}
@dataclass
class AuthMethodsRequest:
username: Optional[str]
password: Optional[str]
methods: bytearray = field(init=False)
def __post_init__(self):
methods = bytearray([AuthMethod.ANONYMOUS])
if self.username and self.password:
methods.append(AuthMethod.USERNAME_PASSWORD)
self.methods = methods
def dumps(self) -> bytes:
return bytes([SOCKS_VER, len(self.methods)]) + self.methods
@dataclass
class AuthMethodReply:
SIZE = 2
ver: int
method: AuthMethod
def validate(self, request: AuthMethodsRequest):
if self.method not in request.methods: # pragma: no cover
raise ReplyError(f'Unexpected SOCKS authentication method: {self.method}')
@classmethod
def loads(cls, data: bytes) -> 'AuthMethodReply':
if len(data) != cls.SIZE:
raise ReplyError('Malformed authentication method reply')
ver = data[0]
if ver != SOCKS_VER: # pragma: no cover
raise ReplyError(f'Unexpected SOCKS version number: {ver}')
try:
method = AuthMethod(data[1])
except ValueError:
raise ReplyError(f'Invalid authentication method: {data[1]:#02X}')
if method == AuthMethod.NO_ACCEPTABLE: # pragma: no cover
raise ReplyError('No acceptable authentication methods were offered')
return cls(ver=ver, method=method)
@dataclass
class AuthRequest:
VER = 0x01
username: str
password: str
def dumps(self) -> bytes:
data = bytearray()
data.append(self.VER)
data.append(len(self.username))
data += self.username.encode('ascii')
data.append(len(self.password))
data += self.password.encode('ascii')
return bytes(data)
@dataclass
class AuthReply:
SIZE = 2
ver: int
status: int
@classmethod
def loads(cls, data: bytes) -> 'AuthReply':
if len(data) != cls.SIZE:
raise ReplyError('Malformed auth reply')
ver = data[0]
if ver != AuthRequest.VER: # pragma: no cover
raise ReplyError('Invalid authentication response')
status = data[1]
if status != AUTH_GRANTED: # pragma: no cover
raise ReplyError('Username and password authentication failure')
return cls(ver=ver, status=status)
@dataclass
class ConnectRequest:
host: str # hostname or IPv4 or IPv6 address
port: int
def dumps(self) -> bytes:
data = bytearray([SOCKS_VER, Command.CONNECT, RSV])
data += self._build_addr_request()
return bytes(data)
def _build_addr_request(self) -> bytes:
port = self.port.to_bytes(2, 'big')
if is_ip_address(self.host):
ip = ipaddress.ip_address(self.host)
address_type = AddressType.from_ip_ver(ip.version)
return bytes([address_type]) + ip.packed + port
else:
address_type = AddressType.DOMAIN
host = self.host.encode('idna')
return bytes([address_type, len(host)]) + host + port
@dataclass
class ConnectReply:
ver: int
reply: ReplyCode
rsv: int
bound_host: str
bound_port: int
def validate(self):
pass
@classmethod
def loads(cls, data: bytes) -> 'ConnectReply':
if not data:
raise ReplyError('Empty connect reply')
ver = data[0]
if ver != SOCKS_VER: # pragma: no cover
raise ReplyError(f'Unexpected SOCKS version number: {ver:#02X}')
try:
reply = ReplyCode(data[1])
except IndexError:
raise ReplyError('Malformed connect reply')
except ValueError:
raise ReplyError(f'Invalid reply code: {data[1]:#02X}')
if reply != ReplyCode.SUCCEEDED: # pragma: no cover
msg = ReplyMessages.get(reply, 'Unknown error') # type: ignore
raise ReplyError(msg, error_code=reply)
try:
rsv = data[2]
except IndexError:
raise ReplyError('Malformed connect reply')
if rsv != RSV: # pragma: no cover
raise ReplyError(f'The reserved byte must be {RSV:#02X}')
try:
addr_type = data[3]
bnd_host_data = data[4:-2]
bnd_port_data = data[-2:]
except IndexError:
raise ReplyError('Malformed connect reply')
if addr_type == AddressType.IPV4:
bnd_host = socket.inet_ntop(socket.AF_INET, bnd_host_data)
elif addr_type == AddressType.IPV6:
bnd_host = socket.inet_ntop(socket.AF_INET6, bnd_host_data)
elif addr_type == AddressType.DOMAIN: # pragma: no cover
# host_len = bnd_host_data[0]
bnd_host = bnd_host_data[1:].decode()
else: # pragma: no cover
raise ReplyError(f'Invalid address type: {addr_type:#02X}')
bnd_port = int.from_bytes(bnd_port_data, 'big')
return cls(
ver=ver,
reply=reply,
rsv=rsv,
bound_host=bnd_host,
bound_port=bnd_port,
)
class StateServerWaitingForAuthMethods:
pass
@dataclass
class StateClientSentAuthMethods:
data: AuthMethodsRequest
@dataclass
class StateServerWaitingForAuth:
data: AuthMethodReply
@dataclass
class StateClientAuthenticated:
data: Optional[AuthReply] = None
@dataclass
class StateClientSentAuthRequest:
data: AuthRequest
@dataclass
class StateClientSentConnectRequest:
data: ConnectRequest
@dataclass
class StateServerConnected:
data: ConnectReply
Request = Union[
AuthMethodsRequest,
AuthRequest,
ConnectRequest,
]
Reply = Union[
AuthMethodReply,
AuthReply,
ConnectReply,
]
ConnectionState = Union[
StateServerWaitingForAuthMethods,
StateClientSentAuthMethods,
StateServerWaitingForAuth,
StateClientSentAuthRequest,
StateClientAuthenticated,
StateClientSentConnectRequest,
StateServerConnected,
]
class Connection:
_state: ConnectionState
def __init__(self):
self._state = StateServerWaitingForAuthMethods()
def send(self, request: Request) -> bytes:
if type(request) is AuthMethodsRequest:
if type(self._state) is not StateServerWaitingForAuthMethods:
raise RuntimeError('Server is not currently waiting for auth methods')
self._state = StateClientSentAuthMethods(request)
return request.dumps()
if type(request) is AuthRequest:
if type(self._state) is not StateServerWaitingForAuth:
raise RuntimeError('Server is not currently waiting for authentication')
self._state = StateClientSentAuthRequest(request)
return request.dumps()
if type(request) is ConnectRequest:
if type(self._state) is not StateClientAuthenticated:
raise RuntimeError('Client is not authenticated')
self._state = StateClientSentConnectRequest(request)
return request.dumps()
raise RuntimeError(f'Invalid request type: {type(request)}')
def receive(self, data: bytes) -> Reply:
if type(self._state) is StateClientSentAuthMethods:
reply = AuthMethodReply.loads(data)
reply.validate(self._state.data)
if reply.method == AuthMethod.USERNAME_PASSWORD:
self._state = StateServerWaitingForAuth(data=reply)
else:
self._state = StateClientAuthenticated()
return reply
if type(self._state) is StateClientSentAuthRequest:
reply = AuthReply.loads(data)
self._state = StateClientAuthenticated(data=reply)
return reply
if type(self._state) is StateClientSentConnectRequest:
reply = ConnectReply.loads(data)
self._state = StateServerConnected(data=reply)
return reply
raise RuntimeError(f'Invalid connection state: {self._state}')
@property
def state(self):
return self._state
|
