from base64 import b64encode from json import JSONDecodeError import logging try: import queue except ImportError: # pragma: no cover import Queue as queue import signal import ssl import threading import time import urllib try: import requests except ImportError: # pragma: no cover requests = None try: import websocket except ImportError: # pragma: no cover websocket = None from . import exceptions from . import packet from . import payload default_logger = logging.getLogger('engineio.client') connected_clients = [] def signal_handler(sig, frame): """SIGINT handler. Disconnect all active clients and then invoke the original signal handler. """ for client in connected_clients[:]: if not client.is_asyncio_based(): client.disconnect() 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): """An Engine.IO client. This class implements a fully compliant Engine.IO web client with support for websocket and long-polling transports. :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. :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``. """ event_names = ['connect', 'disconnect', 'message'] def __init__(self, logger=False, json=None, request_timeout=5, http_session=None, ssl_verify=True): 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.handlers = {} self.base_url = None self.transports = None self.current_transport = None self.sid = None self.upgrades = None self.ping_interval = None self.ping_timeout = None self.http = http_session self.ws = None self.read_loop_task = None self.write_loop_task = None self.queue = None self.state = 'disconnected' self.ssl_verify = ssl_verify if json is not None: packet.Packet.json = json 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.request_timeout = request_timeout def is_asyncio_based(self): return False def on(self, event, handler=None): """Register an event handler. :param event: The event name. Can be ``'connect'``, ``'message'`` or ``'disconnect'``. :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. Example usage:: # as a decorator: @eio.on('connect') def connect_handler(): print('Connection request') # as a method: def message_handler(msg): print('Received message: ', msg) eio.send('response') eio.on('message', message_handler) """ if event not in self.event_names: raise ValueError('Invalid event') def set_handler(handler): self.handlers[event] = handler return handler if handler is None: return set_handler set_handler(handler) def connect(self, url, headers=None, transports=None, engineio_path='engine.io'): """Connect to an Engine.IO server. :param url: The URL of the Engine.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 engineio_path: The endpoint where the Engine.IO server is installed. The default value is appropriate for most cases. Example usage:: eio = engineio.Client() eio.connect('http://localhost:5000') """ if self.state != 'disconnected': raise ValueError('Client is not in a disconnected state') valid_transports = ['polling', 'websocket'] if transports is not None: if isinstance(transports, str): transports = [transports] transports = [transport for transport in transports if transport in valid_transports] if not transports: raise ValueError('No valid transports provided') self.transports = transports or valid_transports self.queue = self.create_queue() return getattr(self, '_connect_' + self.transports[0])( url, headers or {}, engineio_path) 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. """ if self.read_loop_task: self.read_loop_task.join() def send(self, data): """Send a message to a client. :param data: The data to send to the client. Data can be of type ``str``, ``bytes``, ``list`` or ``dict``. If a ``list`` or ``dict``, the data will be serialized as JSON. """ self._send_packet(packet.Packet(packet.MESSAGE, data=data)) def disconnect(self, abort=False): """Disconnect from the server. :param abort: If set to ``True``, do not wait for background tasks associated with the connection to end. """ if self.state == 'connected': self._send_packet(packet.Packet(packet.CLOSE)) self.queue.put(None) self.state = 'disconnecting' self._trigger_event('disconnect', run_async=False) if self.current_transport == 'websocket': self.ws.close() if not abort: self.read_loop_task.join() self.state = 'disconnected' try: connected_clients.remove(self) except ValueError: # pragma: no cover pass self._reset() def transport(self): """Return the name of the transport currently in use. The possible values returned by this function are ``'polling'`` and ``'websocket'``. """ return self.current_transport def start_background_task(self, target, *args, **kwargs): """Start a background task. This is a utility function that applications can use to start a background task. :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. """ th = threading.Thread(target=target, args=args, kwargs=kwargs) th.start() return th def sleep(self, seconds=0): """Sleep for the requested amount of time.""" return time.sleep(seconds) def create_queue(self, *args, **kwargs): """Create a queue object.""" q = queue.Queue(*args, **kwargs) q.Empty = queue.Empty return q def create_event(self, *args, **kwargs): """Create an event object.""" return threading.Event(*args, **kwargs) def _reset(self): self.state = 'disconnected' self.sid = None def _connect_polling(self, url, headers, engineio_path): """Establish a long-polling connection to the Engine.IO server.""" if requests is None: # pragma: no cover # not installed self.logger.error('requests package is not installed -- cannot ' 'send HTTP requests!') return self.base_url = self._get_engineio_url(url, engineio_path, 'polling') self.logger.info('Attempting polling connection to ' + self.base_url) r = self._send_request( 'GET', self.base_url + self._get_url_timestamp(), headers=headers, timeout=self.request_timeout) if r is None: self._reset() raise exceptions.ConnectionError( 'Connection refused by the server') if r.status_code < 200 or r.status_code >= 300: self._reset() try: arg = r.json() except JSONDecodeError: arg = None raise exceptions.ConnectionError( 'Unexpected status code {} in server response'.format( r.status_code), arg) try: p = payload.Payload(encoded_payload=r.content.decode('utf-8')) except ValueError: raise exceptions.ConnectionError( 'Unexpected response from server') from None open_packet = p.packets[0] if open_packet.packet_type != packet.OPEN: raise exceptions.ConnectionError( 'OPEN packet not returned by server') self.logger.info( 'Polling connection accepted with ' + str(open_packet.data)) self.sid = open_packet.data['sid'] self.upgrades = open_packet.data['upgrades'] self.ping_interval = int(open_packet.data['pingInterval']) / 1000.0 self.ping_timeout = int(open_packet.data['pingTimeout']) / 1000.0 self.current_transport = 'polling' self.base_url += '&sid=' + self.sid self.state = 'connected' connected_clients.append(self) self._trigger_event('connect', run_async=False) for pkt in p.packets[1:]: self._receive_packet(pkt) if 'websocket' in self.upgrades and 'websocket' in self.transports: # attempt to upgrade to websocket if self._connect_websocket(url, headers, engineio_path): # upgrade to websocket succeeded, we're done here return # start background tasks associated with this client self.write_loop_task = self.start_background_task(self._write_loop) self.read_loop_task = self.start_background_task( self._read_loop_polling) def _connect_websocket(self, url, headers, engineio_path): """Establish or upgrade to a WebSocket connection with the server.""" if websocket is None: # pragma: no cover # not installed self.logger.warning('websocket-client package not installed, only ' 'polling transport is available') return False websocket_url = self._get_engineio_url(url, engineio_path, 'websocket') if self.sid: self.logger.info( 'Attempting WebSocket upgrade to ' + websocket_url) upgrade = True websocket_url += '&sid=' + self.sid else: upgrade = False self.base_url = websocket_url self.logger.info( 'Attempting WebSocket connection to ' + websocket_url) # get cookies and other settings from the long-polling connection # so that they are preserved when connecting to the WebSocket route cookies = None extra_options = {} if self.http: # cookies cookies = '; '.join(["{}={}".format(cookie.name, cookie.value) for cookie in self.http.cookies]) for header, value in headers.items(): if header.lower() == 'cookie': if cookies: cookies += '; ' cookies += value del headers[header] break # auth if 'Authorization' not in headers and self.http.auth is not None: if not isinstance(self.http.auth, tuple): # pragma: no cover raise ValueError('Only basic authentication is supported') basic_auth = '{}:{}'.format( self.http.auth[0], self.http.auth[1]).encode('utf-8') basic_auth = b64encode(basic_auth).decode('utf-8') headers['Authorization'] = 'Basic ' + basic_auth # cert # this can be given as ('certfile', 'keyfile') or just 'certfile' if isinstance(self.http.cert, tuple): extra_options['sslopt'] = { 'certfile': self.http.cert[0], 'keyfile': self.http.cert[1]} elif self.http.cert: extra_options['sslopt'] = {'certfile': self.http.cert} # proxies if self.http.proxies: proxy_url = None if websocket_url.startswith('ws://'): proxy_url = self.http.proxies.get( 'ws', self.http.proxies.get('http')) else: # wss:// proxy_url = self.http.proxies.get( 'wss', self.http.proxies.get('https')) if proxy_url: parsed_url = urllib.parse.urlparse( proxy_url if '://' in proxy_url else 'scheme://' + proxy_url) extra_options['http_proxy_host'] = parsed_url.hostname extra_options['http_proxy_port'] = parsed_url.port extra_options['http_proxy_auth'] = ( (parsed_url.username, parsed_url.password) if parsed_url.username or parsed_url.password else None) # verify if not self.http.verify: self.ssl_verify = False if not self.ssl_verify: extra_options['sslopt'] = {"cert_reqs": ssl.CERT_NONE} try: ws = websocket.create_connection( websocket_url + self._get_url_timestamp(), header=headers, cookie=cookies, enable_multithread=True, **extra_options) except (ConnectionError, IOError, websocket.WebSocketException): if upgrade: self.logger.warning( 'WebSocket upgrade failed: connection error') return False else: raise exceptions.ConnectionError('Connection error') if upgrade: p = packet.Packet(packet.PING, data='probe').encode() try: ws.send(p) except Exception as e: # pragma: no cover self.logger.warning( 'WebSocket upgrade failed: unexpected send exception: %s', str(e)) return False try: p = ws.recv() except Exception as e: # pragma: no cover self.logger.warning( 'WebSocket upgrade failed: unexpected recv exception: %s', str(e)) return False pkt = packet.Packet(encoded_packet=p) if pkt.packet_type != packet.PONG or pkt.data != 'probe': self.logger.warning( 'WebSocket upgrade failed: no PONG packet') return False p = packet.Packet(packet.UPGRADE).encode() try: ws.send(p) except Exception as e: # pragma: no cover self.logger.warning( 'WebSocket upgrade failed: unexpected send exception: %s', str(e)) return False self.current_transport = 'websocket' self.logger.info('WebSocket upgrade was successful') else: try: p = ws.recv() except Exception as e: # pragma: no cover raise exceptions.ConnectionError( 'Unexpected recv exception: ' + str(e)) open_packet = packet.Packet(encoded_packet=p) if open_packet.packet_type != packet.OPEN: raise exceptions.ConnectionError('no OPEN packet') self.logger.info( 'WebSocket connection accepted with ' + str(open_packet.data)) self.sid = open_packet.data['sid'] self.upgrades = open_packet.data['upgrades'] self.ping_interval = int(open_packet.data['pingInterval']) / 1000.0 self.ping_timeout = int(open_packet.data['pingTimeout']) / 1000.0 self.current_transport = 'websocket' self.state = 'connected' connected_clients.append(self) self._trigger_event('connect', run_async=False) self.ws = ws self.ws.settimeout(self.ping_interval + self.ping_timeout) # start background tasks associated with this client self.write_loop_task = self.start_background_task(self._write_loop) self.read_loop_task = self.start_background_task( self._read_loop_websocket) return True def _receive_packet(self, pkt): """Handle incoming packets from the server.""" packet_name = packet.packet_names[pkt.packet_type] \ if pkt.packet_type < len(packet.packet_names) else 'UNKNOWN' self.logger.info( 'Received packet %s data %s', packet_name, pkt.data if not isinstance(pkt.data, bytes) else '') if pkt.packet_type == packet.MESSAGE: self._trigger_event('message', pkt.data, run_async=True) elif pkt.packet_type == packet.PING: self._send_packet(packet.Packet(packet.PONG, pkt.data)) elif pkt.packet_type == packet.CLOSE: self.disconnect(abort=True) elif pkt.packet_type == packet.NOOP: pass else: self.logger.error('Received unexpected packet of type %s', pkt.packet_type) def _send_packet(self, pkt): """Queue a packet to be sent to the server.""" if self.state != 'connected': return self.queue.put(pkt) self.logger.info( 'Sending packet %s data %s', packet.packet_names[pkt.packet_type], pkt.data if not isinstance(pkt.data, bytes) else '') def _send_request( self, method, url, headers=None, body=None, timeout=None): # pragma: no cover if self.http is None: self.http = requests.Session() try: return self.http.request(method, url, headers=headers, data=body, timeout=timeout, verify=self.ssl_verify) except requests.exceptions.RequestException as exc: self.logger.info('HTTP %s request to %s failed with error %s.', method, url, exc) def _trigger_event(self, event, *args, **kwargs): """Invoke an event handler.""" run_async = kwargs.pop('run_async', False) if event in self.handlers: if run_async: return self.start_background_task(self.handlers[event], *args) else: try: return self.handlers[event](*args) except: self.logger.exception(event + ' handler error') def _get_engineio_url(self, url, engineio_path, transport): """Generate the Engine.IO connection URL.""" engineio_path = engineio_path.strip('/') parsed_url = urllib.parse.urlparse(url) if transport == 'polling': scheme = 'http' elif transport == 'websocket': scheme = 'ws' else: # pragma: no cover raise ValueError('invalid transport') if parsed_url.scheme in ['https', 'wss']: scheme += 's' return ('{scheme}://{netloc}/{path}/?{query}' '{sep}transport={transport}&EIO=4').format( scheme=scheme, netloc=parsed_url.netloc, path=engineio_path, query=parsed_url.query, sep='&' if parsed_url.query else '', transport=transport) def _get_url_timestamp(self): """Generate the Engine.IO query string timestamp.""" return '&t=' + str(time.time()) def _read_loop_polling(self): """Read packets by polling the Engine.IO server.""" while self.state == 'connected': self.logger.info( 'Sending polling GET request to ' + self.base_url) r = self._send_request( 'GET', self.base_url + self._get_url_timestamp(), timeout=max(self.ping_interval, self.ping_timeout) + 5) if r is None: self.logger.warning( 'Connection refused by the server, aborting') self.queue.put(None) break if r.status_code < 200 or r.status_code >= 300: self.logger.warning('Unexpected status code %s in server ' 'response, aborting', r.status_code) self.queue.put(None) break try: p = payload.Payload(encoded_payload=r.content.decode('utf-8')) except ValueError: self.logger.warning( 'Unexpected packet from server, aborting') self.queue.put(None) break for pkt in p.packets: self._receive_packet(pkt) self.logger.info('Waiting for write loop task to end') self.write_loop_task.join() if self.state == 'connected': self._trigger_event('disconnect', run_async=False) try: connected_clients.remove(self) except ValueError: # pragma: no cover pass self._reset() self.logger.info('Exiting read loop task') def _read_loop_websocket(self): """Read packets from the Engine.IO WebSocket connection.""" while self.state == 'connected': p = None try: p = self.ws.recv() except websocket.WebSocketTimeoutException: self.logger.warning( 'Server has stopped communicating, aborting') self.queue.put(None) break except websocket.WebSocketConnectionClosedException: self.logger.warning( 'WebSocket connection was closed, aborting') self.queue.put(None) break except Exception as e: self.logger.info( 'Unexpected error receiving packet: "%s", aborting', str(e)) self.queue.put(None) break try: pkt = packet.Packet(encoded_packet=p) except Exception as e: # pragma: no cover self.logger.info( 'Unexpected error decoding packet: "%s", aborting', str(e)) self.queue.put(None) break self._receive_packet(pkt) self.logger.info('Waiting for write loop task to end') self.write_loop_task.join() if self.state == 'connected': self._trigger_event('disconnect', run_async=False) try: connected_clients.remove(self) except ValueError: # pragma: no cover pass self._reset() self.logger.info('Exiting read loop task') def _write_loop(self): """This background task sends packages to the server as they are pushed to the send queue. """ while self.state == 'connected': # to simplify the timeout handling, use the maximum of the # ping interval and ping timeout as timeout, with an extra 5 # seconds grace period timeout = max(self.ping_interval, self.ping_timeout) + 5 packets = None try: packets = [self.queue.get(timeout=timeout)] except self.queue.Empty: self.logger.error('packet queue is empty, aborting') break if packets == [None]: self.queue.task_done() packets = [] else: while True: try: packets.append(self.queue.get(block=False)) except self.queue.Empty: break if packets[-1] is None: packets = packets[:-1] self.queue.task_done() break if not packets: # empty packet list returned -> connection closed break if self.current_transport == 'polling': p = payload.Payload(packets=packets) r = self._send_request( 'POST', self.base_url, body=p.encode(), headers={'Content-Type': 'application/octet-stream'}, timeout=self.request_timeout) for pkt in packets: self.queue.task_done() if r is None: self.logger.warning( 'Connection refused by the server, aborting') break if r.status_code < 200 or r.status_code >= 300: self.logger.warning('Unexpected status code %s in server ' 'response, aborting', r.status_code) self._reset() break else: # websocket try: for pkt in packets: encoded_packet = pkt.encode() if pkt.binary: self.ws.send_binary(encoded_packet) else: self.ws.send(encoded_packet) self.queue.task_done() except (websocket.WebSocketConnectionClosedException, BrokenPipeError, OSError): self.logger.warning( 'WebSocket connection was closed, aborting') break self.logger.info('Exiting write loop task')