import asyncio import urllib from . import base_server from . import exceptions from . import packet from . import async_socket # this set is used to keep references to background tasks to prevent them from # being garbage collected mid-execution. Solution taken from # https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task task_reference_holder = set() class AsyncServer(base_server.BaseServer): """An Engine.IO server for asyncio. This class implements a fully compliant Engine.IO web server with support for websocket and long-polling transports, compatible with the asyncio framework on Python 3.5 or newer. :param async_mode: The asynchronous model to use. See the Deployment section in the documentation for a description of the available options. Valid async modes are "aiohttp", "sanic", "tornado" and "asgi". If this argument is not given, "aiohttp" is tried first, followed by "sanic", "tornado", and finally "asgi". The first async mode that has all its dependencies installed is the one that is chosen. :param ping_interval: The interval in seconds at which the server pings the client. The default is 25 seconds. For advanced control, a two element tuple can be given, where the first number is the ping interval and the second is a grace period added by the server. :param ping_timeout: The time in seconds that the client waits for the server to respond before disconnecting. The default is 20 seconds. :param max_http_buffer_size: The maximum size that is accepted for incoming messages. The default is 1,000,000 bytes. In spite of its name, the value set in this argument is enforced for HTTP long-polling and WebSocket connections. :param allow_upgrades: Whether to allow transport upgrades or not. :param http_compression: Whether to compress packages when using the polling transport. :param compression_threshold: Only compress messages when their byte size is greater than this value. :param cookie: If set to a string, it is the name of the HTTP cookie the server sends back tot he client containing the client session id. If set to a dictionary, the ``'name'`` key contains the cookie name and other keys define cookie attributes, where the value of each attribute can be a string, a callable with no arguments, or a boolean. If set to ``None`` (the default), a cookie is not sent to the client. :param cors_allowed_origins: Origin or list of origins that are allowed to connect to this server. Only the same origin is allowed by default. Set this argument to ``'*'`` to allow all origins, or to ``[]`` to disable CORS handling. :param cors_credentials: Whether credentials (cookies, authentication) are allowed in requests to this server. :param logger: To enable logging set to ``True`` or pass a logger object to use. To disable logging set to ``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 async_handlers: If set to ``True``, run message event handlers in non-blocking threads. To run handlers synchronously, set to ``False``. The default is ``True``. :param transports: The list of allowed transports. Valid transports are ``'polling'`` and ``'websocket'``. Defaults to ``['polling', 'websocket']``. :param kwargs: Reserved for future extensions, any additional parameters given as keyword arguments will be silently ignored. """ def is_asyncio_based(self): return True def async_modes(self): return ['aiohttp', 'sanic', 'tornado', 'asgi'] def attach(self, app, engineio_path='engine.io'): """Attach the Engine.IO server to an application.""" engineio_path = engineio_path.strip('/') self._async['create_route'](app, self, '/{}/'.format(engineio_path)) async def send(self, sid, data): """Send a message to a client. :param sid: The session id of the recipient 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. Note: this method is a coroutine. """ await self.send_packet(sid, packet.Packet(packet.MESSAGE, data=data)) async def send_packet(self, sid, pkt): """Send a raw packet to a client. :param sid: The session id of the recipient client. :param pkt: The packet to send to the client. Note: this method is a coroutine. """ try: socket = self._get_socket(sid) except KeyError: # the socket is not available self.logger.warning('Cannot send to sid %s', sid) return await socket.send(pkt) async def get_session(self, sid): """Return the user session for a client. :param sid: The session id of the client. The return value is a dictionary. Modifications made to this dictionary are not guaranteed to be preserved. If you want to modify the user session, use the ``session`` context manager instead. """ socket = self._get_socket(sid) return socket.session async def save_session(self, sid, session): """Store the user session for a client. :param sid: The session id of the client. :param session: The session dictionary. """ socket = self._get_socket(sid) socket.session = session def session(self, sid): """Return the user session for a client with context manager syntax. :param sid: The session id of the client. This is a context manager that returns the user session dictionary for the client. Any changes that are made to this dictionary inside the context manager block are saved back to the session. Example usage:: @eio.on('connect') def on_connect(sid, environ): username = authenticate_user(environ) if not username: return False with eio.session(sid) as session: session['username'] = username @eio.on('message') def on_message(sid, msg): async with eio.session(sid) as session: print('received message from ', session['username']) """ class _session_context_manager(object): def __init__(self, server, sid): self.server = server self.sid = sid self.session = None async def __aenter__(self): self.session = await self.server.get_session(sid) return self.session async def __aexit__(self, *args): await self.server.save_session(sid, self.session) return _session_context_manager(self, sid) async def disconnect(self, sid=None): """Disconnect a client. :param sid: The session id of the client to close. If this parameter is not given, then all clients are closed. Note: this method is a coroutine. """ if sid is not None: try: socket = self._get_socket(sid) except KeyError: # pragma: no cover # the socket was already closed or gone pass else: await socket.close() if sid in self.sockets: # pragma: no cover del self.sockets[sid] else: await asyncio.wait([asyncio.create_task(client.close()) for client in self.sockets.values()]) self.sockets = {} async def handle_request(self, *args, **kwargs): """Handle an HTTP request from the client. This is the entry point of the Engine.IO application. This function returns the HTTP response to deliver to the client. Note: this method is a coroutine. """ translate_request = self._async['translate_request'] if asyncio.iscoroutinefunction(translate_request): environ = await translate_request(*args, **kwargs) else: environ = translate_request(*args, **kwargs) if self.cors_allowed_origins != []: # Validate the origin header if present # This is important for WebSocket more than for HTTP, since # browsers only apply CORS controls to HTTP. origin = environ.get('HTTP_ORIGIN') if origin: allowed_origins = self._cors_allowed_origins(environ) if allowed_origins is not None and origin not in \ allowed_origins: self._log_error_once( origin + ' is not an accepted origin.', 'bad-origin') return await self._make_response( self._bad_request( origin + ' is not an accepted origin.'), environ) method = environ['REQUEST_METHOD'] query = urllib.parse.parse_qs(environ.get('QUERY_STRING', '')) sid = query['sid'][0] if 'sid' in query else None jsonp = False jsonp_index = None # make sure the client uses an allowed transport transport = query.get('transport', ['polling'])[0] if transport not in self.transports: self._log_error_once('Invalid transport', 'bad-transport') return await self._make_response( self._bad_request('Invalid transport'), environ) # make sure the client speaks a compatible Engine.IO version sid = query['sid'][0] if 'sid' in query else None if sid is None and query.get('EIO') != ['4']: self._log_error_once( 'The client is using an unsupported version of the Socket.IO ' 'or Engine.IO protocols', 'bad-version' ) return await self._make_response(self._bad_request( 'The client is using an unsupported version of the Socket.IO ' 'or Engine.IO protocols' ), environ) if 'j' in query: jsonp = True try: jsonp_index = int(query['j'][0]) except (ValueError, KeyError, IndexError): # Invalid JSONP index number pass if jsonp and jsonp_index is None: self._log_error_once('Invalid JSONP index number', 'bad-jsonp-index') r = self._bad_request('Invalid JSONP index number') elif method == 'GET': if sid is None: # transport must be one of 'polling' or 'websocket'. # if 'websocket', the HTTP_UPGRADE header must match. upgrade_header = environ.get('HTTP_UPGRADE').lower() \ if 'HTTP_UPGRADE' in environ else None if transport == 'polling' \ or transport == upgrade_header == 'websocket': r = await self._handle_connect(environ, transport, jsonp_index) else: self._log_error_once('Invalid websocket upgrade', 'bad-upgrade') r = self._bad_request('Invalid websocket upgrade') else: if sid not in self.sockets: self._log_error_once('Invalid session ' + sid, 'bad-sid') r = self._bad_request('Invalid session ' + sid) else: socket = self._get_socket(sid) try: packets = await socket.handle_get_request(environ) if isinstance(packets, list): r = self._ok(packets, jsonp_index=jsonp_index) else: r = packets except exceptions.EngineIOError: if sid in self.sockets: # pragma: no cover await self.disconnect(sid) r = self._bad_request() if sid in self.sockets and self.sockets[sid].closed: del self.sockets[sid] elif method == 'POST': if sid is None or sid not in self.sockets: self._log_error_once('Invalid session ' + sid, 'bad-sid') r = self._bad_request('Invalid session ' + sid) else: socket = self._get_socket(sid) try: await socket.handle_post_request(environ) r = self._ok(jsonp_index=jsonp_index) except exceptions.EngineIOError: if sid in self.sockets: # pragma: no cover await self.disconnect(sid) r = self._bad_request() except: # pragma: no cover # for any other unexpected errors, we log the error # and keep going self.logger.exception('post request handler error') r = self._ok(jsonp_index=jsonp_index) elif method == 'OPTIONS': r = self._ok() else: self.logger.warning('Method %s not supported', method) r = self._method_not_found() if not isinstance(r, dict): return r if self.http_compression and \ len(r['response']) >= self.compression_threshold: encodings = [e.split(';')[0].strip() for e in environ.get('HTTP_ACCEPT_ENCODING', '').split(',')] for encoding in encodings: if encoding in self.compression_methods: r['response'] = \ getattr(self, '_' + encoding)(r['response']) r['headers'] += [('Content-Encoding', encoding)] break return await self._make_response(r, environ) async def shutdown(self): """Stop Socket.IO background tasks. This method stops background activity initiated by the Socket.IO server. It must be called before shutting down the web server. """ self.logger.info('Socket.IO is shutting down') if self.service_task_event: # pragma: no cover self.service_task_event.set() await self.service_task_handle self.service_task_handle = None 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. The return value is a ``asyncio.Task`` object. """ return asyncio.ensure_future(target(*args, **kwargs)) async 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. Note: this method is a coroutine. """ return await asyncio.sleep(seconds) def create_queue(self, *args, **kwargs): """Create a queue object using the appropriate async model. This is a utility function that applications can use to create a queue without having to worry about using the correct call for the selected async mode. For asyncio based async modes, this returns an instance of ``asyncio.Queue``. """ return asyncio.Queue(*args, **kwargs) def get_queue_empty_exception(self): """Return the queue empty exception for the appropriate async model. This is a utility function that applications can use to work with a queue without having to worry about using the correct call for the selected async mode. For asyncio based async modes, this returns an instance of ``asyncio.QueueEmpty``. """ return asyncio.QueueEmpty def create_event(self, *args, **kwargs): """Create an event object using the appropriate async model. This is a utility function that applications can use to create an event without having to worry about using the correct call for the selected async mode. For asyncio based async modes, this returns an instance of ``asyncio.Event``. """ return asyncio.Event(*args, **kwargs) async def _make_response(self, response_dict, environ): cors_headers = self._cors_headers(environ) make_response = self._async['make_response'] if asyncio.iscoroutinefunction(make_response): response = await make_response( response_dict['status'], response_dict['headers'] + cors_headers, response_dict['response'], environ) else: response = make_response( response_dict['status'], response_dict['headers'] + cors_headers, response_dict['response'], environ) return response async def _handle_connect(self, environ, transport, jsonp_index=None): """Handle a client connection request.""" if self.start_service_task: # start the service task to monitor connected clients self.start_service_task = False self.service_task_handle = self.start_background_task( self._service_task) sid = self.generate_id() s = async_socket.AsyncSocket(self, sid) self.sockets[sid] = s pkt = packet.Packet( packet.OPEN, {'sid': sid, 'upgrades': self._upgrades(sid, transport), 'pingTimeout': int(self.ping_timeout * 1000), 'pingInterval': int(self.ping_interval * 1000)}) await s.send(pkt) s.schedule_ping() ret = await self._trigger_event('connect', sid, environ, run_async=False) if ret is not None and ret is not True: del self.sockets[sid] self.logger.warning('Application rejected connection') return self._unauthorized(ret or None) if transport == 'websocket': ret = await s.handle_get_request(environ) if s.closed and sid in self.sockets: # websocket connection ended, so we are done del self.sockets[sid] return ret else: s.connected = True headers = None if self.cookie: if isinstance(self.cookie, dict): headers = [( 'Set-Cookie', self._generate_sid_cookie(sid, self.cookie) )] else: headers = [( 'Set-Cookie', self._generate_sid_cookie(sid, { 'name': self.cookie, 'path': '/', 'SameSite': 'Lax' }) )] try: return self._ok(await s.poll(), headers=headers, jsonp_index=jsonp_index) except exceptions.QueueEmpty: return self._bad_request() async def _trigger_event(self, event, *args, **kwargs): """Invoke an event handler.""" run_async = kwargs.pop('run_async', False) ret = None if event in self.handlers: if asyncio.iscoroutinefunction(self.handlers[event]): async def run_async_handler(): try: return await self.handlers[event](*args) except asyncio.CancelledError: # pragma: no cover pass except: self.logger.exception(event + ' async handler error') if event == 'connect': # if connect handler raised error we reject the # connection return False if run_async: ret = self.start_background_task(run_async_handler) task_reference_holder.add(ret) ret.add_done_callback(task_reference_holder.discard) else: ret = await run_async_handler() else: async def run_sync_handler(): try: return self.handlers[event](*args) except: self.logger.exception(event + ' handler error') if event == 'connect': # if connect handler raised error we reject the # connection return False if run_async: ret = self.start_background_task(run_sync_handler) task_reference_holder.add(ret) ret.add_done_callback(task_reference_holder.discard) else: ret = await run_sync_handler() return ret async def _service_task(self): # pragma: no cover """Monitor connected clients and clean up those that time out.""" self.service_task_event = self.create_event() while not self.service_task_event.is_set(): if len(self.sockets) == 0: # nothing to do try: await asyncio.wait_for(self.service_task_event.wait(), timeout=self.ping_timeout) except asyncio.TimeoutError: break continue # go through the entire client list in a ping interval cycle sleep_interval = self.ping_timeout / len(self.sockets) try: # iterate over the current clients for s in self.sockets.copy().values(): if s.closed: try: del self.sockets[s.sid] except KeyError: # the socket could have also been removed by # the _get_socket() method from another thread pass elif not s.closing: await s.check_ping_timeout() try: await asyncio.wait_for(self.service_task_event.wait(), timeout=sleep_interval) except asyncio.TimeoutError: raise KeyboardInterrupt() except ( SystemExit, KeyboardInterrupt, asyncio.CancelledError, GeneratorExit, ): self.logger.info('service task canceled') break except: if asyncio.get_event_loop().is_closed(): self.logger.info('event loop is closed, exiting service ' 'task') break # an unexpected exception has occurred, log it and continue self.logger.exception('service task exception')