import random import engineio from . import base_client from . import exceptions from . import packet class Client(base_client.BaseClient): """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 infinite 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 serializer: The serialization method to use when transmitting packets. Valid values are ``'default'``, ``'pickle'``, ``'msgpack'`` and ``'cbor'``. Alternatively, a subclass of the :class:`Packet` class with custom implementations of the ``encode()`` and ``decode()`` methods can be provided. Client and server must use compatible serializers. :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. :param handle_sigint: Set to ``True`` to automatically handle disconnection when the process is interrupted, or to ``False`` to leave interrupt handling to the calling application. Interrupt handling can only be enabled when the client instance is created in the main thread. 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 connect(self, url, headers={}, auth=None, transports=None, namespaces=None, socketio_path='socket.io', wait=True, wait_timeout=1, retry=False): """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. If a function is provided, the client will invoke it to obtain the URL each time a connection or reconnection is attempted. :param headers: A dictionary with custom headers to send with the connection request. If a function is provided, the client will invoke it to obtain the headers dictionary each time a connection or reconnection is attempted. :param auth: Authentication data passed to the server with the connection request, normally a dictionary with one or more string key/value pairs. If a function is provided, the client will invoke it to obtain the authentication data each time a connection or reconnection is attempted. :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. :param wait: if set to ``True`` (the default) the call only returns when all the namespaces are connected. If set to ``False``, the call returns as soon as the Engine.IO transport is connected, and the namespaces will connect in the background. :param wait_timeout: How long the client should wait for the connection. The default is 1 second. This argument is only considered when ``wait`` is set to ``True``. :param retry: Apply the reconnection logic if the initial connection attempt fails. The default is ``False``. Example usage:: sio = socketio.Client() sio.connect('http://localhost:5000') """ if self.connected: raise exceptions.ConnectionError('Already connected') self.connection_url = url self.connection_headers = headers self.connection_auth = auth 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 self.namespaces = {} if self._connect_event is None: self._connect_event = self.eio.create_event() else: self._connect_event.clear() real_url = self._get_real_value(self.connection_url) real_headers = self._get_real_value(self.connection_headers) try: self.eio.connect(real_url, headers=real_headers, transports=transports, engineio_path=socketio_path) except engineio.exceptions.ConnectionError as exc: for n in self.connection_namespaces: self._trigger_event( 'connect_error', n, exc.args[1] if len(exc.args) > 1 else exc.args[0]) if retry: # pragma: no cover self._handle_reconnect() if self.eio.state == 'connected': return raise exceptions.ConnectionError(exc.args[0]) from None if wait: while self._connect_event.wait(timeout=wait_timeout): self._connect_event.clear() if set(self.namespaces) == set(self.connection_namespaces): break if set(self.namespaces) != set(self.connection_namespaces): self.disconnect() raise exceptions.ConnectionError( 'One or more namespaces failed to connect') 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 the server. :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 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(self.packet_class(packet.EVENT, namespace=namespace, data=[event] + data, id=id)) def send(self, data, namespace=None, callback=None): """Send a message to the server. 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 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 the server and wait for the response. This method issues an emit with a callback and waits for the callback to be invoked before returning. If the callback isn't invoked before the timeout, then a ``TimeoutError`` exception is raised. If the Socket.IO connection drops during the wait, this method still waits until the specified timeout. :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 server 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(self.packet_class( packet.DISCONNECT, namespace=n)) self.eio.disconnect(abort=True) 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 that represents the background task, on which the ``join()`` methond can be invoked to wait for the task to complete. """ 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 _get_real_value(self, value): """Return the actual value, for parameters that can also be given as callables.""" if not callable(value): return value return value() 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 _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) self._connect_event.set() def _handle_disconnect(self, namespace): if not self.connected: return namespace = namespace or '/' self._trigger_event('disconnect', namespace=namespace) self._trigger_event('__disconnect_final', 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(self.packet_class( 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) self._connect_event.set() 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 handler, args = self._get_event_handler(event, namespace, args) if handler: return handler(*args) # or else, forward the event to a namespace handler if one exists handler, args = self._get_namespace_handler(namespace, args) if handler: return handler.trigger_event(event, *args) def _handle_reconnect(self): if self._reconnect_abort is None: # pragma: no cover self._reconnect_abort = self.eio.create_event() self._reconnect_abort.clear() base_client.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') for n in self.connection_namespaces: self._trigger_event('__disconnect_final', namespace=n) break attempt_count += 1 try: self.connect(self.connection_url, headers=self.connection_headers, auth=self.connection_auth, transports=self.connection_transports, namespaces=self.connection_namespaces, socketio_path=self.socketio_path, retry=False) 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') for n in self.connection_namespaces: self._trigger_event('__disconnect_final', namespace=n) break base_client.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 real_auth = self._get_real_value(self.connection_auth) or {} for n in self.connection_namespaces: self._send_packet(self.packet_class( packet.CONNECT, data=real_auth, 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 = self.packet_class(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') will_reconnect = self.reconnection and self.eio.state == 'connected' if self.connected: for n in self.namespaces: self._trigger_event('disconnect', namespace=n) if not will_reconnect: self._trigger_event('__disconnect_final', namespace=n) self.namespaces = {} self.connected = False self.callbacks = {} self._binary_packet = None self.sid = None if will_reconnect: self._reconnect_task = self.start_background_task( self._handle_reconnect) def _engineio_client_class(self): return engineio.Client