import itertools
import logging
import random
import signal
import threading
import engineio
from . import exceptions
from . import namespace
from . import packet
default_logger = logging.getLogger('socketio.client')
reconnecting_clients = []
def signal_handler(sig, frame): # pragma: no cover
"""SIGINT handler.
Notify any clients that are in a reconnect loop to abort. Other
disconnection tasks are handled at the engine.io level.
"""
for client in reconnecting_clients[:]:
client._reconnect_abort.set()
if callable(original_signal_handler):
return original_signal_handler(sig, frame)
else: # pragma: no cover
# Handle case where no original SIGINT handler was present.
return signal.default_int_handler(sig, frame)
original_signal_handler = None
class Client(object):
"""A Socket.IO client.
This class implements a fully compliant Socket.IO web client with support
for websocket and long-polling transports.
:param reconnection: ``True`` if the client should automatically attempt to
reconnect to the server after an interruption, or
``False`` to not reconnect. The default is ``True``.
:param reconnection_attempts: How many reconnection attempts to issue
before giving up, or 0 for infinity attempts.
The default is 0.
:param reconnection_delay: How long to wait in seconds before the first
reconnection attempt. Each successive attempt
doubles this delay.
:param reconnection_delay_max: The maximum delay between reconnection
attempts.
:param randomization_factor: Randomization amount for each delay between
reconnection attempts. The default is 0.5,
which means that each delay is randomly
adjusted by +/- 50%.
:param logger: To enable logging set to ``True`` or pass a logger object to
use. To disable logging set to ``False``. The default is
``False``. Note that fatal errors are logged even when
``logger`` is ``False``.
:param json: An alternative json module to use for encoding and decoding
packets. Custom json modules must have ``dumps`` and ``loads``
functions that are compatible with the standard library
versions.
The Engine.IO configuration supports the following settings:
:param request_timeout: A timeout in seconds for requests. The default is
5 seconds.
:param http_session: an initialized ``requests.Session`` object to be used
when sending requests to the server. Use it if you
need to add special client options such as proxy
servers, SSL certificates, etc.
:param ssl_verify: ``True`` to verify SSL certificates, or ``False`` to
skip SSL certificate verification, allowing
connections to servers with self signed certificates.
The default is ``True``.
:param engineio_logger: To enable Engine.IO logging set to ``True`` or pass
a logger object to use. To disable logging set to
``False``. The default is ``False``. Note that
fatal errors are logged even when
``engineio_logger`` is ``False``.
"""
def __init__(self, reconnection=True, reconnection_attempts=0,
reconnection_delay=1, reconnection_delay_max=5,
randomization_factor=0.5, logger=False, json=None, **kwargs):
global original_signal_handler
if original_signal_handler is None and \
threading.current_thread() == threading.main_thread():
original_signal_handler = signal.signal(signal.SIGINT,
signal_handler)
self.reconnection = reconnection
self.reconnection_attempts = reconnection_attempts
self.reconnection_delay = reconnection_delay
self.reconnection_delay_max = reconnection_delay_max
self.randomization_factor = randomization_factor
engineio_options = kwargs
engineio_logger = engineio_options.pop('engineio_logger', None)
if engineio_logger is not None:
engineio_options['logger'] = engineio_logger
if json is not None:
packet.Packet.json = json
engineio_options['json'] = json
self.eio = self._engineio_client_class()(**engineio_options)
self.eio.on('connect', self._handle_eio_connect)
self.eio.on('message', self._handle_eio_message)
self.eio.on('disconnect', self._handle_eio_disconnect)
if not isinstance(logger, bool):
self.logger = logger
else:
self.logger = default_logger
if self.logger.level == logging.NOTSET:
if logger:
self.logger.setLevel(logging.INFO)
else:
self.logger.setLevel(logging.ERROR)
self.logger.addHandler(logging.StreamHandler())
self.connection_url = None
self.connection_headers = None
self.connection_transports = None
self.connection_namespaces = []
self.socketio_path = None
self.sid = None
self.connected = False
self.namespaces = {}
self.handlers = {}
self.namespace_handlers = {}
self.callbacks = {}
self._binary_packet = None
self._reconnect_task = None
self._reconnect_abort = self.eio.create_event()
def is_asyncio_based(self):
return False
def on(self, event, handler=None, namespace=None):
"""Register an event handler.
:param event: The event name. It can be any string. The event names
``'connect'``, ``'message'`` and ``'disconnect'`` are
reserved and should not be used.
:param handler: The function that should be invoked to handle the
event. When this parameter is not given, the method
acts as a decorator for the handler function.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the handler is associated with
the default namespace.
Example usage::
# as a decorator:
@sio.on('connect')
def connect_handler():
print('Connected!')
# as a method:
def message_handler(msg):
print('Received message: ', msg)
sio.send( 'response')
sio.on('message', message_handler)
The ``'connect'`` event handler receives no arguments. The
``'message'`` handler and handlers for custom event names receive the
message payload as only argument. Any values returned from a message
handler will be passed to the client's acknowledgement callback
function if it exists. The ``'disconnect'`` handler does not take
arguments.
"""
namespace = namespace or '/'
def set_handler(handler):
if namespace not in self.handlers:
self.handlers[namespace] = {}
self.handlers[namespace][event] = handler
return handler
if handler is None:
return set_handler
set_handler(handler)
def event(self, *args, **kwargs):
"""Decorator to register an event handler.
This is a simplified version of the ``on()`` method that takes the
event name from the decorated function.
Example usage::
@sio.event
def my_event(data):
print('Received data: ', data)
The above example is equivalent to::
@sio.on('my_event')
def my_event(data):
print('Received data: ', data)
A custom namespace can be given as an argument to the decorator::
@sio.event(namespace='/test')
def my_event(data):
print('Received data: ', data)
"""
if len(args) == 1 and len(kwargs) == 0 and callable(args[0]):
# the decorator was invoked without arguments
# args[0] is the decorated function
return self.on(args[0].__name__)(args[0])
else:
# the decorator was invoked with arguments
def set_handler(handler):
return self.on(handler.__name__, *args, **kwargs)(handler)
return set_handler
def register_namespace(self, namespace_handler):
"""Register a namespace handler object.
:param namespace_handler: An instance of a :class:`Namespace`
subclass that handles all the event traffic
for a namespace.
"""
if not isinstance(namespace_handler, namespace.ClientNamespace):
raise ValueError('Not a namespace instance')
if self.is_asyncio_based() != namespace_handler.is_asyncio_based():
raise ValueError('Not a valid namespace class for this client')
namespace_handler._set_client(self)
self.namespace_handlers[namespace_handler.namespace] = \
namespace_handler
def connect(self, url, headers={}, transports=None,
namespaces=None, socketio_path='socket.io'):
"""Connect to a Socket.IO server.
:param url: The URL of the Socket.IO server. It can include custom
query string parameters if required by the server.
:param headers: A dictionary with custom headers to send with the
connection request.
:param transports: The list of allowed transports. Valid transports
are ``'polling'`` and ``'websocket'``. If not
given, the polling transport is connected first,
then an upgrade to websocket is attempted.
:param namespaces: The namespaces to connect as a string or list of
strings. If not given, the namespaces that have
registered event handlers are connected.
:param socketio_path: The endpoint where the Socket.IO server is
installed. The default value is appropriate for
most cases.
Note: The connection mechannism occurs in the background and will
complete at some point after this function returns. The connection
will be established when the ``connect`` event is invoked.
Example usage::
sio = socketio.Client()
sio.connect('http://localhost:5000')
"""
self.connection_url = url
self.connection_headers = headers
self.connection_transports = transports
self.connection_namespaces = namespaces
self.socketio_path = socketio_path
if namespaces is None:
namespaces = list(set(self.handlers.keys()).union(
set(self.namespace_handlers.keys())))
if len(namespaces) == 0:
namespaces = ['/']
elif isinstance(namespaces, str):
namespaces = [namespaces]
self.connection_namespaces = namespaces
try:
self.eio.connect(url, headers=headers, transports=transports,
engineio_path=socketio_path)
except engineio.exceptions.ConnectionError as exc:
self._trigger_event(
'connect_error', '/',
exc.args[1] if len(exc.args) > 1 else exc.args[0])
raise exceptions.ConnectionError(exc.args[0]) from None
self.connected = True
def wait(self):
"""Wait until the connection with the server ends.
Client applications can use this function to block the main thread
during the life of the connection.
"""
while True:
self.eio.wait()
self.sleep(1) # give the reconnect task time to start up
if not self._reconnect_task:
break
self._reconnect_task.join()
if self.eio.state != 'connected':
break
def emit(self, event, data=None, namespace=None, callback=None):
"""Emit a custom event to one or more connected clients.
:param event: The event name. It can be any string. The event names
``'connect'``, ``'message'`` and ``'disconnect'`` are
reserved and should not be used.
:param data: The data to send to the server. Data can be of
type ``str``, ``bytes``, ``list`` or ``dict``. To send
multiple arguments, use a tuple where each element is of
one of the types indicated above.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the event is emitted to the
default namespace.
:param callback: If given, this function will be called to acknowledge
the the server has received the message. The arguments
that will be passed to the function are those provided
by the server.
Note: this method is not thread safe. If multiple threads are emitting
at the same time on the same client connection, messages composed of
multiple packets may end up being sent in an incorrect sequence. Use
standard concurrency solutions (such as a Lock object) to prevent this
situation.
"""
namespace = namespace or '/'
if namespace not in self.namespaces:
raise exceptions.BadNamespaceError(
namespace + ' is not a connected namespace.')
self.logger.info('Emitting event "%s" [%s]', event, namespace)
if callback is not None:
id = self._generate_ack_id(namespace, callback)
else:
id = None
# tuples are expanded to multiple arguments, everything else is sent
# as a single argument
if isinstance(data, tuple):
data = list(data)
elif data is not None:
data = [data]
else:
data = []
self._send_packet(packet.Packet(packet.EVENT, namespace=namespace,
data=[event] + data, id=id))
def send(self, data, namespace=None, callback=None):
"""Send a message to one or more connected clients.
This function emits an event with the name ``'message'``. Use
:func:`emit` to issue custom event names.
:param data: The data to send to the server. Data can be of
type ``str``, ``bytes``, ``list`` or ``dict``. To send
multiple arguments, use a tuple where each element is of
one of the types indicated above.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the event is emitted to the
default namespace.
:param callback: If given, this function will be called to acknowledge
the the server has received the message. The arguments
that will be passed to the function are those provided
by the server.
"""
self.emit('message', data=data, namespace=namespace,
callback=callback)
def call(self, event, data=None, namespace=None, timeout=60):
"""Emit a custom event to a client and wait for the response.
:param event: The event name. It can be any string. The event names
``'connect'``, ``'message'`` and ``'disconnect'`` are
reserved and should not be used.
:param data: The data to send to the server. Data can be of
type ``str``, ``bytes``, ``list`` or ``dict``. To send
multiple arguments, use a tuple where each element is of
one of the types indicated above.
:param namespace: The Socket.IO namespace for the event. If this
argument is omitted the event is emitted to the
default namespace.
:param timeout: The waiting timeout. If the timeout is reached before
the client acknowledges the event, then a
``TimeoutError`` exception is raised.
Note: this method is not thread safe. If multiple threads are emitting
at the same time on the same client connection, messages composed of
multiple packets may end up being sent in an incorrect sequence. Use
standard concurrency solutions (such as a Lock object) to prevent this
situation.
"""
callback_event = self.eio.create_event()
callback_args = []
def event_callback(*args):
callback_args.append(args)
callback_event.set()
self.emit(event, data=data, namespace=namespace,
callback=event_callback)
if not callback_event.wait(timeout=timeout):
raise exceptions.TimeoutError()
return callback_args[0] if len(callback_args[0]) > 1 \
else callback_args[0][0] if len(callback_args[0]) == 1 \
else None
def disconnect(self):
"""Disconnect from the server."""
# here we just request the disconnection
# later in _handle_eio_disconnect we invoke the disconnect handler
for n in self.namespaces:
self._send_packet(packet.Packet(packet.DISCONNECT, namespace=n))
self.eio.disconnect(abort=True)
def get_sid(self, namespace=None):
"""Return the ``sid`` associated with a connection.
:param namespace: The Socket.IO namespace. If this argument is omitted
the handler is associated with the default
namespace. Note that unlike previous versions, the
current version of the Socket.IO protocol uses
different ``sid`` values per namespace.
This method returns the ``sid`` for the requested namespace as a
string.
"""
return self.namespaces.get(namespace or '/')
def transport(self):
"""Return the name of the transport used by the client.
The two possible values returned by this function are ``'polling'``
and ``'websocket'``.
"""
return self.eio.transport()
def start_background_task(self, target, *args, **kwargs):
"""Start a background task using the appropriate async model.
This is a utility function that applications can use to start a
background task using the method that is compatible with the
selected async mode.
:param target: the target function to execute.
:param args: arguments to pass to the function.
:param kwargs: keyword arguments to pass to the function.
This function returns an object compatible with the `Thread` class in
the Python standard library. The `start()` method on this object is
already called by this function.
"""
return self.eio.start_background_task(target, *args, **kwargs)
def sleep(self, seconds=0):
"""Sleep for the requested amount of time using the appropriate async
model.
This is a utility function that applications can use to put a task to
sleep without having to worry about using the correct call for the
selected async mode.
"""
return self.eio.sleep(seconds)
def _send_packet(self, pkt):
"""Send a Socket.IO packet to the server."""
encoded_packet = pkt.encode()
if isinstance(encoded_packet, list):
for ep in encoded_packet:
self.eio.send(ep)
else:
self.eio.send(encoded_packet)
def _generate_ack_id(self, namespace, callback):
"""Generate a unique identifier for an ACK packet."""
namespace = namespace or '/'
if namespace not in self.callbacks:
self.callbacks[namespace] = {0: itertools.count(1)}
id = next(self.callbacks[namespace][0])
self.callbacks[namespace][id] = callback
return id
def _handle_connect(self, namespace, data):
namespace = namespace or '/'
if namespace not in self.namespaces:
self.logger.info('Namespace {} is connected'.format(namespace))
self.namespaces[namespace] = (data or {}).get('sid', self.sid)
self._trigger_event('connect', namespace=namespace)
def _handle_disconnect(self, namespace):
if not self.connected:
return
namespace = namespace or '/'
self._trigger_event('disconnect', namespace=namespace)
if namespace in self.namespaces:
del self.namespaces[namespace]
if not self.namespaces:
self.connected = False
self.eio.disconnect(abort=True)
def _handle_event(self, namespace, id, data):
namespace = namespace or '/'
self.logger.info('Received event "%s" [%s]', data[0], namespace)
r = self._trigger_event(data[0], namespace, *data[1:])
if id is not None:
# send ACK packet with the response returned by the handler
# tuples are expanded as multiple arguments
if r is None:
data = []
elif isinstance(r, tuple):
data = list(r)
else:
data = [r]
self._send_packet(packet.Packet(packet.ACK, namespace=namespace,
id=id, data=data))
def _handle_ack(self, namespace, id, data):
namespace = namespace or '/'
self.logger.info('Received ack [%s]', namespace)
callback = None
try:
callback = self.callbacks[namespace][id]
except KeyError:
# if we get an unknown callback we just ignore it
self.logger.warning('Unknown callback received, ignoring.')
else:
del self.callbacks[namespace][id]
if callback is not None:
callback(*data)
def _handle_error(self, namespace, data):
namespace = namespace or '/'
self.logger.info('Connection to namespace {} was rejected'.format(
namespace))
if data is None:
data = tuple()
elif not isinstance(data, (tuple, list)):
data = (data,)
self._trigger_event('connect_error', namespace, *data)
if namespace in self.namespaces:
del self.namespaces[namespace]
if namespace == '/':
self.namespaces = {}
self.connected = False
def _trigger_event(self, event, namespace, *args):
"""Invoke an application event handler."""
# first see if we have an explicit handler for the event
if namespace in self.handlers and event in self.handlers[namespace]:
return self.handlers[namespace][event](*args)
# or else, forward the event to a namespace handler if one exists
elif namespace in self.namespace_handlers:
return self.namespace_handlers[namespace].trigger_event(
event, *args)
def _handle_reconnect(self):
self._reconnect_abort.clear()
reconnecting_clients.append(self)
attempt_count = 0
current_delay = self.reconnection_delay
while True:
delay = current_delay
current_delay *= 2
if delay > self.reconnection_delay_max:
delay = self.reconnection_delay_max
delay += self.randomization_factor * (2 * random.random() - 1)
self.logger.info(
'Connection failed, new attempt in {:.02f} seconds'.format(
delay))
if self._reconnect_abort.wait(delay):
self.logger.info('Reconnect task aborted')
break
attempt_count += 1
try:
self.connect(self.connection_url,
headers=self.connection_headers,
transports=self.connection_transports,
namespaces=self.connection_namespaces,
socketio_path=self.socketio_path)
except (exceptions.ConnectionError, ValueError):
pass
else:
self.logger.info('Reconnection successful')
self._reconnect_task = None
break
if self.reconnection_attempts and \
attempt_count >= self.reconnection_attempts:
self.logger.info(
'Maximum reconnection attempts reached, giving up')
break
reconnecting_clients.remove(self)
def _handle_eio_connect(self):
"""Handle the Engine.IO connection event."""
self.logger.info('Engine.IO connection established')
self.sid = self.eio.sid
for n in self.connection_namespaces:
self._send_packet(packet.Packet(packet.CONNECT, namespace=n))
def _handle_eio_message(self, data):
"""Dispatch Engine.IO messages."""
if self._binary_packet:
pkt = self._binary_packet
if pkt.add_attachment(data):
self._binary_packet = None
if pkt.packet_type == packet.BINARY_EVENT:
self._handle_event(pkt.namespace, pkt.id, pkt.data)
else:
self._handle_ack(pkt.namespace, pkt.id, pkt.data)
else:
pkt = packet.Packet(encoded_packet=data)
if pkt.packet_type == packet.CONNECT:
self._handle_connect(pkt.namespace, pkt.data)
elif pkt.packet_type == packet.DISCONNECT:
self._handle_disconnect(pkt.namespace)
elif pkt.packet_type == packet.EVENT:
self._handle_event(pkt.namespace, pkt.id, pkt.data)
elif pkt.packet_type == packet.ACK:
self._handle_ack(pkt.namespace, pkt.id, pkt.data)
elif pkt.packet_type == packet.BINARY_EVENT or \
pkt.packet_type == packet.BINARY_ACK:
self._binary_packet = pkt
elif pkt.packet_type == packet.CONNECT_ERROR:
self._handle_error(pkt.namespace, pkt.data)
else:
raise ValueError('Unknown packet type.')
def _handle_eio_disconnect(self):
"""Handle the Engine.IO disconnection event."""
self.logger.info('Engine.IO connection dropped')
if self.connected:
for n in self.namespaces:
self._trigger_event('disconnect', namespace=n)
self.namespaces = {}
self.connected = False
self.callbacks = {}
self._binary_packet = None
self.sid = None
if self.eio.state == 'connected' and self.reconnection:
self._reconnect_task = self.start_background_task(
self._handle_reconnect)
def _engineio_client_class(self):
return engineio.Client