# Copyright 2011-2020, Damian Johnson and The Tor Project
# See LICENSE for licensing information
"""
Supports communication with sockets speaking Tor protocols. This
allows us to send messages as basic strings, and receive responses as
:class:`~stem.response.ControlMessage` instances.
**This module only consists of low level components, and is not intended for
users.** See our `tutorials <../tutorials.html>`_ and `Control Module
<control.html>`_ if you're new to Stem and looking to get started.
With that aside, these can still be used for raw socket communication with
Tor...
::
import stem
import stem.connection
import stem.socket
if __name__ == '__main__':
try:
control_socket = stem.socket.ControlPort(port = 9051)
stem.connection.authenticate(control_socket)
except stem.SocketError as exc:
print 'Unable to connect to tor on port 9051: %s' % exc
sys.exit(1)
except stem.connection.AuthenticationFailure as exc:
print 'Unable to authenticate: %s' % exc
sys.exit(1)
print "Issuing 'GETINFO version' query...\\n"
control_socket.send('GETINFO version')
print control_socket.recv()
::
% python example.py
Issuing 'GETINFO version' query...
version=0.2.4.10-alpha-dev (git-8be6058d8f31e578)
OK
**Module Overview:**
::
BaseSocket - Thread safe socket.
|- RelaySocket - Socket for a relay's ORPort.
| |- send - sends a message to the socket
| +- recv - receives a response from the socket
|
|- ControlSocket - Socket wrapper that speaks the tor control protocol.
| |- ControlPort - Control connection via a port.
| |- ControlSocketFile - Control connection via a local file socket.
| |
| |- send - sends a message to the socket
| +- recv - receives a ControlMessage from the socket
|
|- is_alive - reports if the socket is known to be closed
|- is_localhost - returns if the socket is for the local system or not
|- connection_time - timestamp when socket last connected or disconnected
|- connect - connects a new socket
+- close - shuts down the socket
send_message - Writes a message to a control socket.
recv_message - Reads a ControlMessage from a control socket.
send_formatting - Performs the formatting expected from sent messages.
"""
import re
import socket
import ssl
import threading
import time
import stem.response
import stem.util.str_tools
from stem.util import log
from types import TracebackType
from typing import BinaryIO, Callable, List, Optional, Tuple, Type, Union, overload
MESSAGE_PREFIX = re.compile(b'^[a-zA-Z0-9]{3}[-+ ]')
ERROR_MSG = 'Error while receiving a control message (%s): %s'
# lines to limit our trace logging to, you can disable this by setting it to None
TRUNCATE_LOGS = 10
class BaseSocket(object):
"""
Thread safe socket, providing common socket functionality.
"""
def __init__(self) -> None:
self._socket = None # type: Optional[Union[socket.socket, ssl.SSLSocket]]
self._socket_file = None # type: Optional[BinaryIO]
self._is_alive = False
self._connection_time = 0.0 # time when we last connected or disconnected
# Tracks sending and receiving separately. This should be safe, and doing
# so prevents deadlock where we block writes because we're waiting to read
# a message that isn't coming.
self._send_lock = threading.RLock()
self._recv_lock = threading.RLock()
def is_alive(self) -> bool:
"""
Checks if the socket is known to be closed. We won't be aware if it is
until we either use it or have explicitily shut it down.
In practice a socket derived from a port knows about its disconnection
after failing to receive data, whereas socket file derived connections
know after either sending or receiving data.
This means that to have reliable detection for when we're disconnected
you need to continually pull from the socket (which is part of what the
:class:`~stem.control.BaseController` does).
:returns: **bool** that's **True** if our socket is connected and **False**
otherwise
"""
return self._is_alive
def is_localhost(self) -> bool:
"""
Returns if the connection is for the local system or not.
:returns: **bool** that's **True** if the connection is for the local host
and **False** otherwise
"""
return False
def connection_time(self) -> float:
"""
Provides the unix timestamp for when our socket was either connected or
disconnected. That is to say, the time we connected if we're currently
connected and the time we disconnected if we're not connected.
.. versionadded:: 1.3.0
:returns: **float** for when we last connected or disconnected, zero if
we've never connected
"""
return self._connection_time
def connect(self) -> None:
"""
Connects to a new socket, closing our previous one if we're already
attached.
:raises: :class:`stem.SocketError` if unable to make a socket
"""
with self._send_lock:
# Closes the socket if we're currently attached to one. Once we're no
# longer alive it'll be safe to acquire the recv lock because recv()
# calls no longer block (raising SocketClosed instead).
if self.is_alive():
self.close()
with self._recv_lock:
self._socket = self._make_socket()
self._socket_file = self._socket.makefile(mode = 'rwb')
self._is_alive = True
self._connection_time = time.time()
# It's possible for this to have a transient failure...
# SocketError: [Errno 4] Interrupted system call
#
# It's safe to retry, so give it another try if it fails.
try:
self._connect()
except stem.SocketError:
self._connect() # single retry
def close(self) -> None:
"""
Shuts down the socket. If it's already closed then this is a no-op.
"""
with self._send_lock:
# Function is idempotent with one exception: we notify _close() if this
# is causing our is_alive() state to change.
is_change = self.is_alive()
if self._socket:
# if we haven't yet established a connection then this raises an error
# socket.error: [Errno 107] Transport endpoint is not connected
try:
self._socket.shutdown(socket.SHUT_RDWR)
except socket.error:
pass
self._socket.close()
if self._socket_file:
try:
self._socket_file.close()
except BrokenPipeError:
pass
self._socket = None
self._socket_file = None
self._is_alive = False
self._connection_time = time.time()
if is_change:
self._close()
def _send(self, message: Union[bytes, str], handler: Callable[[Union[socket.socket, ssl.SSLSocket], BinaryIO, Union[bytes, str]], None]) -> None:
"""
Send message in a thread safe manner. Handler is expected to be of the form...
::
my_handler(socket, socket_file, message)
"""
with self._send_lock:
try:
if not self.is_alive():
raise stem.SocketClosed()
handler(self._socket, self._socket_file, message)
except stem.SocketClosed:
# if send_message raises a SocketClosed then we should properly shut
# everything down
if self.is_alive():
self.close()
raise
@overload
def _recv(self, handler: Callable[[ssl.SSLSocket, BinaryIO], bytes]) -> bytes:
...
@overload
def _recv(self, handler: Callable[[socket.socket, BinaryIO], stem.response.ControlMessage]) -> stem.response.ControlMessage:
...
def _recv(self, handler):
"""
Receives a message in a thread safe manner. Handler is expected to be of the form...
::
my_handler(socket, socket_file)
"""
with self._recv_lock:
try:
# makes a temporary reference to the _socket_file because connect()
# and close() may set or unset it
my_socket, my_socket_file = self._socket, self._socket_file
if not my_socket or not my_socket_file:
raise stem.SocketClosed()
return handler(my_socket, my_socket_file)
except stem.SocketClosed:
# If recv_message raises a SocketClosed then we should properly shut
# everything down. However, there's a couple cases where this will
# cause deadlock...
#
# * This SocketClosed was *caused by* a close() call, which is joining
# on our thread.
#
# * A send() call that's currently in flight is about to call close(),
# also attempting to join on us.
#
# To resolve this we make a non-blocking call to acquire the send lock.
# If we get it then great, we can close safely. If not then one of the
# above are in progress and we leave the close to them.
if self.is_alive():
if self._send_lock.acquire(False):
self.close()
self._send_lock.release()
raise
def _get_send_lock(self) -> threading.RLock:
"""
The send lock is useful to classes that interact with us at a deep level
because it's used to lock :func:`stem.socket.ControlSocket.connect` /
:func:`stem.socket.BaseSocket.close`, and by extension our
:func:`stem.socket.BaseSocket.is_alive` state changes.
:returns: **threading.RLock** that governs sending messages to our socket
and state changes
"""
return self._send_lock
def __enter__(self) -> 'stem.socket.BaseSocket':
return self
def __exit__(self, exit_type: Optional[Type[BaseException]], value: Optional[BaseException], traceback: Optional[TracebackType]):
self.close()
def _connect(self) -> None:
"""
Connection callback that can be overwritten by subclasses and wrappers.
"""
pass
def _close(self) -> None:
"""
Disconnection callback that can be overwritten by subclasses and wrappers.
"""
pass
def _make_socket(self) -> Union[socket.socket, ssl.SSLSocket]:
"""
Constructs and connects new socket. This is implemented by subclasses.
:returns: **socket.socket** for our configuration
:raises:
* :class:`stem.SocketError` if unable to make a socket
* **NotImplementedError** if not implemented by a subclass
"""
raise NotImplementedError('Unsupported Operation: this should be implemented by the BaseSocket subclass')
class RelaySocket(BaseSocket):
"""
`Link-level connection
<https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt>`_ to a Tor
relay.
.. versionadded:: 1.7.0
:var str address: address our socket connects to
:var int port: ORPort our socket connects to
"""
def __init__(self, address: str = '127.0.0.1', port: int = 9050, connect: bool = True) -> None:
"""
RelaySocket constructor.
:param address: ip address of the relay
:param port: orport of the relay
:param connect: connects to the socket if True, leaves it unconnected otherwise
:raises: :class:`stem.SocketError` if connect is **True** and we're
unable to establish a connection
"""
super(RelaySocket, self).__init__()
self.address = address
self.port = port
if connect:
self.connect()
def send(self, message: Union[str, bytes]) -> None:
"""
Sends a message to the relay's ORPort.
:param message: message to be formatted and sent to the socket
:raises:
* :class:`stem.SocketError` if a problem arises in using the socket
* :class:`stem.SocketClosed` if the socket is known to be shut down
"""
self._send(message, lambda s, sf, msg: _write_to_socket(sf, msg))
def recv(self, timeout: Optional[float] = None) -> bytes:
"""
Receives a message from the relay.
:param timeout: maxiumum number of seconds to await a response, this
blocks indefinitely if **None**
:returns: bytes for the message received
:raises:
* :class:`stem.ProtocolError` the content from the socket is malformed
* :class:`stem.SocketClosed` if the socket closes before we receive a complete message
"""
def wrapped_recv(s: ssl.SSLSocket, sf: BinaryIO) -> bytes:
if timeout is None:
return s.recv(1024)
else:
s.setblocking(False)
s.settimeout(timeout)
try:
return s.recv(1024)
except (socket.timeout, ssl.SSLError, ssl.SSLWantReadError):
return None
finally:
s.setblocking(True)
return self._recv(wrapped_recv)
def is_localhost(self) -> bool:
return self.address == '127.0.0.1'
def _make_socket(self) -> ssl.SSLSocket:
try:
relay_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
relay_socket.connect((self.address, self.port))
return ssl.wrap_socket(relay_socket)
except socket.error as exc:
raise stem.SocketError(exc)
class ControlSocket(BaseSocket):
"""
Wrapper for a socket connection that speaks the Tor control protocol. To the
better part this transparently handles the formatting for sending and
receiving complete messages.
Callers should not instantiate this class directly, but rather use subclasses
which are expected to implement the **_make_socket()** method.
"""
def __init__(self) -> None:
super(ControlSocket, self).__init__()
def send(self, message: Union[bytes, str]) -> None:
"""
Formats and sends a message to the control socket. For more information see
the :func:`~stem.socket.send_message` function.
:param message: message to be formatted and sent to the socket
:raises:
* :class:`stem.SocketError` if a problem arises in using the socket
* :class:`stem.SocketClosed` if the socket is known to be shut down
"""
self._send(message, lambda s, sf, msg: send_message(sf, msg))
def recv(self) -> stem.response.ControlMessage:
"""
Receives a message from the control socket, blocking until we've received
one. For more information see the :func:`~stem.socket.recv_message` function.
:returns: :class:`~stem.response.ControlMessage` for the message received
:raises:
* :class:`stem.ProtocolError` the content from the socket is malformed
* :class:`stem.SocketClosed` if the socket closes before we receive a complete message
"""
return self._recv(lambda s, sf: recv_message(sf))
class ControlPort(ControlSocket):
"""
Control connection to tor. For more information see tor's ControlPort torrc
option.
:var str address: address our socket connects to
:var int port: ControlPort our socket connects to
"""
def __init__(self, address: str = '127.0.0.1', port: int = 9051, connect: bool = True) -> None:
"""
ControlPort constructor.
:param address: ip address of the controller
:param port: port number of the controller
:param connect: connects to the socket if True, leaves it unconnected otherwise
:raises: :class:`stem.SocketError` if connect is **True** and we're
unable to establish a connection
"""
super(ControlPort, self).__init__()
self.address = address
self.port = port
if connect:
self.connect()
def is_localhost(self) -> bool:
return self.address == '127.0.0.1'
def _make_socket(self) -> socket.socket:
try:
control_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
control_socket.connect((self.address, self.port))
return control_socket
except socket.error as exc:
raise stem.SocketError(exc)
class ControlSocketFile(ControlSocket):
"""
Control connection to tor. For more information see tor's ControlSocket torrc
option.
:var str path: filesystem path of the socket we connect to
"""
def __init__(self, path: str = '/var/run/tor/control', connect: bool = True) -> None:
"""
ControlSocketFile constructor.
:param socket_path: path where the control socket is located
:param connect: connects to the socket if True, leaves it unconnected otherwise
:raises: :class:`stem.SocketError` if connect is **True** and we're
unable to establish a connection
"""
super(ControlSocketFile, self).__init__()
self.path = path
if connect:
self.connect()
def is_localhost(self) -> bool:
return True
def _make_socket(self) -> socket.socket:
try:
control_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
control_socket.connect(self.path)
return control_socket
except socket.error as exc:
raise stem.SocketError(exc)
def send_message(control_file: BinaryIO, message: Union[bytes, str], raw: bool = False) -> None:
"""
Sends a message to the control socket, adding the expected formatting for
single verses multi-line messages. Neither message type should contain an
ending newline (if so it'll be treated as a multi-line message with a blank
line at the end). If the message doesn't contain a newline then it's sent
as...
::
<message>\\r\\n
and if it does contain newlines then it's split on ``\\n`` and sent as...
::
+<line 1>\\r\\n
<line 2>\\r\\n
<line 3>\\r\\n
.\\r\\n
:param control_file: file derived from the control socket (see the
socket's makefile() method for more information)
:param message: message to be sent on the control socket
:param raw: leaves the message formatting untouched, passing it to the
socket as-is
:raises:
* :class:`stem.SocketError` if a problem arises in using the socket
* :class:`stem.SocketClosed` if the socket is known to be shut down
"""
message = stem.util.str_tools._to_unicode(message)
if not raw:
message = send_formatting(message)
_write_to_socket(control_file, message)
if log.is_tracing():
log_message = message.replace('\r\n', '\n').rstrip()
msg_div = '\n' if '\n' in log_message else ' '
log.trace('Sent to tor:%s%s' % (msg_div, log_message))
def _write_to_socket(socket_file: BinaryIO, message: Union[str, bytes]) -> None:
try:
socket_file.write(stem.util.str_tools._to_bytes(message))
socket_file.flush()
except socket.error as exc:
log.info('Failed to send: %s' % exc)
# When sending there doesn't seem to be a reliable method for
# distinguishing between failures from a disconnect verses other things.
# Just accounting for known disconnection responses.
if str(exc) == '[Errno 32] Broken pipe':
raise stem.SocketClosed(exc)
else:
raise stem.SocketError(exc)
except AttributeError:
# if the control_file has been closed then flush will receive:
# AttributeError: 'NoneType' object has no attribute 'sendall'
log.info('Failed to send: file has been closed')
raise stem.SocketClosed('file has been closed')
def recv_message(control_file: BinaryIO, arrived_at: Optional[float] = None) -> stem.response.ControlMessage:
"""
Pulls from a control socket until we either have a complete message or
encounter a problem.
:param control_file: file derived from the control socket (see the
socket's makefile() method for more information)
:returns: :class:`~stem.response.ControlMessage` read from the socket
:raises:
* :class:`stem.ProtocolError` the content from the socket is malformed
* :class:`stem.SocketClosed` if the socket closes before we receive
a complete message
"""
parsed_content = [] # type: List[Tuple[str, str, bytes]]
raw_content = bytearray()
first_line = True
while True:
try:
line = control_file.readline()
except AttributeError:
# if the control_file has been closed then we will receive:
# AttributeError: 'NoneType' object has no attribute 'recv'
log.info(ERROR_MSG % ('SocketClosed', 'socket file has been closed'))
raise stem.SocketClosed('socket file has been closed')
except (OSError, ValueError) as exc:
# when disconnected this errors with...
#
# * ValueError: I/O operation on closed file
# * OSError: [Errno 107] Transport endpoint is not connected
# * OSError: [Errno 9] Bad file descriptor
log.info(ERROR_MSG % ('SocketClosed', 'received exception "%s"' % exc))
raise stem.SocketClosed(exc)
# Parses the tor control lines. These are of the form...
# <status code><divider><content>\r\n
if not line:
# if the socket is disconnected then the readline() method will provide
# empty content
log.info(ERROR_MSG % ('SocketClosed', 'empty socket content'))
raise stem.SocketClosed('Received empty socket content.')
elif not MESSAGE_PREFIX.match(line):
log.info(ERROR_MSG % ('ProtocolError', 'malformed status code/divider, "%s"' % log.escape(line.decode('utf-8'))))
raise stem.ProtocolError('Badly formatted reply line: beginning is malformed')
elif not line.endswith(b'\r\n'):
log.info(ERROR_MSG % ('ProtocolError', 'no CRLF linebreak, "%s"' % log.escape(line.decode('utf-8'))))
raise stem.ProtocolError('All lines should end with CRLF')
status_code, divider, content = line[:3], line[3:4], line[4:-2] # strip CRLF off content
status_code = stem.util.str_tools._to_unicode(status_code)
divider = stem.util.str_tools._to_unicode(divider)
# Most controller responses are single lines, in which case we don't need
# so much overhead.
if first_line:
if divider == ' ':
_log_trace(line)
return stem.response.ControlMessage([(status_code, divider, content)], line, arrived_at = arrived_at)
else:
parsed_content, raw_content, first_line = [], bytearray(), False
raw_content += line
if divider == '-':
# mid-reply line, keep pulling for more content
parsed_content.append((status_code, divider, content))
elif divider == ' ':
# end of the message, return the message
parsed_content.append((status_code, divider, content))
_log_trace(bytes(raw_content))
return stem.response.ControlMessage(parsed_content, bytes(raw_content), arrived_at = arrived_at)
elif divider == '+':
# data entry, all of the following lines belong to the content until we
# get a line with just a period
content_block = bytearray(content)
while True:
try:
line = control_file.readline()
raw_content += line
except socket.error as exc:
log.info(ERROR_MSG % ('SocketClosed', 'received an exception while mid-way through a data reply (exception: "%s", read content: "%s")' % (exc, log.escape(bytes(raw_content).decode('utf-8')))))
raise stem.SocketClosed(exc)
if not line.endswith(b'\r\n'):
log.info(ERROR_MSG % ('ProtocolError', 'CRLF linebreaks missing from a data reply, "%s"' % log.escape(bytes(raw_content).decode('utf-8'))))
raise stem.ProtocolError('All lines should end with CRLF')
elif line == b'.\r\n':
break # data block termination
line = line[:-2] # strips off the CRLF
# lines starting with a period are escaped by a second period (as per
# section 2.4 of the control-spec)
if line.startswith(b'..'):
line = line[1:]
content_block += b'\n' + line
# joins the content using a newline rather than CRLF separator (more
# conventional for multi-line string content outside the windows world)
parsed_content.append((status_code, divider, bytes(content_block)))
else:
# this should never be reached due to the prefix regex, but might as well
# be safe...
log.warn(ERROR_MSG % ('ProtocolError', "\"%s\" isn't a recognized divider type" % divider))
raise stem.ProtocolError("Unrecognized divider type '%s': %s" % (divider, stem.util.str_tools._to_unicode(line)))
def send_formatting(message: str) -> str:
"""
Performs the formatting expected from sent control messages. For more
information see the :func:`~stem.socket.send_message` function.
:param message: message to be formatted
:returns: **str** of the message wrapped by the formatting expected from
controllers
"""
# From control-spec section 2.2...
# Command = Keyword OptArguments CRLF / "+" Keyword OptArguments CRLF CmdData
# Keyword = 1*ALPHA
# OptArguments = [ SP *(SP / VCHAR) ]
#
# A command is either a single line containing a Keyword and arguments, or a
# multiline command whose initial keyword begins with +, and whose data
# section ends with a single "." on a line of its own.
# if we already have \r\n entries then standardize on \n to start with
message = message.replace('\r\n', '\n')
if '\n' in message:
return '+%s\r\n.\r\n' % message.replace('\n', '\r\n')
else:
return message + '\r\n'
def _log_trace(response: bytes) -> None:
if not log.is_tracing():
return
log_message = stem.util.str_tools._to_unicode(response.replace(b'\r\n', b'\n').rstrip())
log_message_lines = log_message.split('\n')
if TRUNCATE_LOGS and len(log_message_lines) > TRUNCATE_LOGS:
log_message = '\n'.join(log_message_lines[:TRUNCATE_LOGS] + ['... %i more lines...' % (len(log_message_lines) - TRUNCATE_LOGS)])
if len(log_message_lines) > 2:
log.trace('Received from tor:\n%s' % log_message)
else:
log.trace('Received from tor: %s' % log_message.replace('\n', '\\n'))
