339 lines
14 KiB
Python
339 lines
14 KiB
Python
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import base64
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import gzip
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import importlib
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import io
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import logging
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import secrets
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import zlib
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from . import packet
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from . import payload
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default_logger = logging.getLogger('engineio.server')
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class BaseServer:
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compression_methods = ['gzip', 'deflate']
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event_names = ['connect', 'disconnect', 'message']
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valid_transports = ['polling', 'websocket']
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_default_monitor_clients = True
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sequence_number = 0
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def __init__(self, async_mode=None, ping_interval=25, ping_timeout=20,
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max_http_buffer_size=1000000, allow_upgrades=True,
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http_compression=True, compression_threshold=1024,
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cookie=None, cors_allowed_origins=None,
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cors_credentials=True, logger=False, json=None,
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async_handlers=True, monitor_clients=None, transports=None,
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**kwargs):
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self.ping_timeout = ping_timeout
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if isinstance(ping_interval, tuple):
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self.ping_interval = ping_interval[0]
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self.ping_interval_grace_period = ping_interval[1]
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else:
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self.ping_interval = ping_interval
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self.ping_interval_grace_period = 0
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self.max_http_buffer_size = max_http_buffer_size
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self.allow_upgrades = allow_upgrades
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self.http_compression = http_compression
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self.compression_threshold = compression_threshold
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self.cookie = cookie
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self.cors_allowed_origins = cors_allowed_origins
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self.cors_credentials = cors_credentials
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self.async_handlers = async_handlers
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self.sockets = {}
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self.handlers = {}
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self.log_message_keys = set()
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self.start_service_task = monitor_clients \
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if monitor_clients is not None else self._default_monitor_clients
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self.service_task_handle = None
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self.service_task_event = None
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if json is not None:
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packet.Packet.json = json
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if not isinstance(logger, bool):
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self.logger = logger
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else:
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self.logger = default_logger
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if self.logger.level == logging.NOTSET:
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if logger:
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self.logger.setLevel(logging.INFO)
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else:
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self.logger.setLevel(logging.ERROR)
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self.logger.addHandler(logging.StreamHandler())
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modes = self.async_modes()
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if async_mode is not None:
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modes = [async_mode] if async_mode in modes else []
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self._async = None
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self.async_mode = None
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for mode in modes:
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try:
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self._async = importlib.import_module(
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'engineio.async_drivers.' + mode)._async
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asyncio_based = self._async['asyncio'] \
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if 'asyncio' in self._async else False
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if asyncio_based != self.is_asyncio_based():
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continue # pragma: no cover
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self.async_mode = mode
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break
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except ImportError:
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pass
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if self.async_mode is None:
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raise ValueError('Invalid async_mode specified')
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if self.is_asyncio_based() and \
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('asyncio' not in self._async or not
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self._async['asyncio']): # pragma: no cover
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raise ValueError('The selected async_mode is not asyncio '
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'compatible')
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if not self.is_asyncio_based() and 'asyncio' in self._async and \
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self._async['asyncio']: # pragma: no cover
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raise ValueError('The selected async_mode requires asyncio and '
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'must use the AsyncServer class')
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if transports is not None:
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if isinstance(transports, str):
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transports = [transports]
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transports = [transport for transport in transports
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if transport in self.valid_transports]
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if not transports:
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raise ValueError('No valid transports provided')
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self.transports = transports or self.valid_transports
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self.logger.info('Server initialized for %s.', self.async_mode)
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def is_asyncio_based(self):
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return False
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def async_modes(self):
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return ['eventlet', 'gevent_uwsgi', 'gevent', 'threading']
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def on(self, event, handler=None):
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"""Register an event handler.
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:param event: The event name. Can be ``'connect'``, ``'message'`` or
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``'disconnect'``.
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:param handler: The function that should be invoked to handle the
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event. When this parameter is not given, the method
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acts as a decorator for the handler function.
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Example usage::
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# as a decorator:
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@eio.on('connect')
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def connect_handler(sid, environ):
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print('Connection request')
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if environ['REMOTE_ADDR'] in blacklisted:
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return False # reject
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# as a method:
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def message_handler(sid, msg):
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print('Received message: ', msg)
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eio.send(sid, 'response')
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eio.on('message', message_handler)
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The handler function receives the ``sid`` (session ID) for the
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client as first argument. The ``'connect'`` event handler receives the
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WSGI environment as a second argument, and can return ``False`` to
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reject the connection. The ``'message'`` handler receives the message
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payload as a second argument. The ``'disconnect'`` handler does not
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take a second argument.
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"""
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if event not in self.event_names:
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raise ValueError('Invalid event')
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def set_handler(handler):
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self.handlers[event] = handler
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return handler
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if handler is None:
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return set_handler
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set_handler(handler)
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def transport(self, sid):
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"""Return the name of the transport used by the client.
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The two possible values returned by this function are ``'polling'``
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and ``'websocket'``.
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:param sid: The session of the client.
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"""
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return 'websocket' if self._get_socket(sid).upgraded else 'polling'
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def create_queue(self, *args, **kwargs):
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"""Create a queue object using the appropriate async model.
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This is a utility function that applications can use to create a queue
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without having to worry about using the correct call for the selected
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async mode.
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"""
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return self._async['queue'](*args, **kwargs)
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def get_queue_empty_exception(self):
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"""Return the queue empty exception for the appropriate async model.
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This is a utility function that applications can use to work with a
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queue without having to worry about using the correct call for the
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selected async mode.
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"""
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return self._async['queue_empty']
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def create_event(self, *args, **kwargs):
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"""Create an event object using the appropriate async model.
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This is a utility function that applications can use to create an
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event without having to worry about using the correct call for the
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selected async mode.
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"""
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return self._async['event'](*args, **kwargs)
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def generate_id(self):
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"""Generate a unique session id."""
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id = base64.b64encode(
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secrets.token_bytes(12) + self.sequence_number.to_bytes(3, 'big'))
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self.sequence_number = (self.sequence_number + 1) & 0xffffff
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return id.decode('utf-8').replace('/', '_').replace('+', '-')
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def _generate_sid_cookie(self, sid, attributes):
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"""Generate the sid cookie."""
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cookie = attributes.get('name', 'io') + '=' + sid
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for attribute, value in attributes.items():
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if attribute == 'name':
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continue
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if callable(value):
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value = value()
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if value is True:
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cookie += '; ' + attribute
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else:
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cookie += '; ' + attribute + '=' + value
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return cookie
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def _upgrades(self, sid, transport):
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"""Return the list of possible upgrades for a client connection."""
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if not self.allow_upgrades or self._get_socket(sid).upgraded or \
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transport == 'websocket':
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return []
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if self._async['websocket'] is None: # pragma: no cover
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self._log_error_once(
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'The WebSocket transport is not available, you must install a '
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'WebSocket server that is compatible with your async mode to '
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'enable it. See the documentation for details.',
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'no-websocket')
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return []
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return ['websocket']
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def _get_socket(self, sid):
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"""Return the socket object for a given session."""
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try:
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s = self.sockets[sid]
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except KeyError:
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raise KeyError('Session not found')
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if s.closed:
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del self.sockets[sid]
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raise KeyError('Session is disconnected')
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return s
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def _ok(self, packets=None, headers=None, jsonp_index=None):
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"""Generate a successful HTTP response."""
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if packets is not None:
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if headers is None:
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headers = []
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headers += [('Content-Type', 'text/plain; charset=UTF-8')]
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return {'status': '200 OK',
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'headers': headers,
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'response': payload.Payload(packets=packets).encode(
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jsonp_index=jsonp_index).encode('utf-8')}
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else:
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return {'status': '200 OK',
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'headers': [('Content-Type', 'text/plain')],
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'response': b'OK'}
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def _bad_request(self, message=None):
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"""Generate a bad request HTTP error response."""
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if message is None:
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message = 'Bad Request'
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message = packet.Packet.json.dumps(message)
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return {'status': '400 BAD REQUEST',
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'headers': [('Content-Type', 'text/plain')],
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'response': message.encode('utf-8')}
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def _method_not_found(self):
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"""Generate a method not found HTTP error response."""
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return {'status': '405 METHOD NOT FOUND',
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'headers': [('Content-Type', 'text/plain')],
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'response': b'Method Not Found'}
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def _unauthorized(self, message=None):
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"""Generate a unauthorized HTTP error response."""
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if message is None:
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message = 'Unauthorized'
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message = packet.Packet.json.dumps(message)
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return {'status': '401 UNAUTHORIZED',
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'headers': [('Content-Type', 'application/json')],
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'response': message.encode('utf-8')}
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def _cors_allowed_origins(self, environ):
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default_origins = []
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if 'wsgi.url_scheme' in environ and 'HTTP_HOST' in environ:
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default_origins.append('{scheme}://{host}'.format(
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scheme=environ['wsgi.url_scheme'], host=environ['HTTP_HOST']))
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if 'HTTP_X_FORWARDED_PROTO' in environ or \
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'HTTP_X_FORWARDED_HOST' in environ:
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scheme = environ.get(
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'HTTP_X_FORWARDED_PROTO',
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environ['wsgi.url_scheme']).split(',')[0].strip()
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default_origins.append('{scheme}://{host}'.format(
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scheme=scheme, host=environ.get(
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'HTTP_X_FORWARDED_HOST', environ['HTTP_HOST']).split(
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',')[0].strip()))
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if self.cors_allowed_origins is None:
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allowed_origins = default_origins
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elif self.cors_allowed_origins == '*':
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allowed_origins = None
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elif isinstance(self.cors_allowed_origins, str):
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allowed_origins = [self.cors_allowed_origins]
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elif callable(self.cors_allowed_origins):
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origin = environ.get('HTTP_ORIGIN')
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allowed_origins = [origin] \
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if self.cors_allowed_origins(origin) else []
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else:
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allowed_origins = self.cors_allowed_origins
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return allowed_origins
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def _cors_headers(self, environ):
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"""Return the cross-origin-resource-sharing headers."""
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if self.cors_allowed_origins == []:
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# special case, CORS handling is completely disabled
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return []
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headers = []
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allowed_origins = self._cors_allowed_origins(environ)
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if 'HTTP_ORIGIN' in environ and \
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(allowed_origins is None or environ['HTTP_ORIGIN'] in
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allowed_origins):
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headers = [('Access-Control-Allow-Origin', environ['HTTP_ORIGIN'])]
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if environ['REQUEST_METHOD'] == 'OPTIONS':
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headers += [('Access-Control-Allow-Methods', 'OPTIONS, GET, POST')]
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if 'HTTP_ACCESS_CONTROL_REQUEST_HEADERS' in environ:
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headers += [('Access-Control-Allow-Headers',
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environ['HTTP_ACCESS_CONTROL_REQUEST_HEADERS'])]
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if self.cors_credentials:
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headers += [('Access-Control-Allow-Credentials', 'true')]
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return headers
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def _gzip(self, response):
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"""Apply gzip compression to a response."""
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bytesio = io.BytesIO()
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with gzip.GzipFile(fileobj=bytesio, mode='w') as gz:
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gz.write(response)
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return bytesio.getvalue()
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def _deflate(self, response):
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"""Apply deflate compression to a response."""
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return zlib.compress(response)
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def _log_error_once(self, message, message_key):
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"""Log message with logging.ERROR level the first time, then log
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with given level."""
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if message_key not in self.log_message_keys:
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self.logger.error(message + ' (further occurrences of this error '
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'will be logged with level INFO)')
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self.log_message_keys.add(message_key)
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else:
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self.logger.info(message)
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