import asyncio
import six
from six.moves import urllib
from . import exceptions
from . import packet
from . import server
from . import asyncio_socket
class AsyncServer(server.Server):
"""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, an async mode is chosen based on the installed
packages.
:param ping_timeout: The time in seconds that the client waits for the
server to respond before disconnecting.
:param ping_interval: The interval in seconds at which the client pings
the server.
:param max_http_buffer_size: The maximum size of a message when using the
polling transport.
: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: Name of the HTTP cookie that contains the client session
id. If set to ``None``, a cookie is not sent to the client.
:param cors_allowed_origins: List of origins that are allowed to connect
to this server. All origins are allowed by
default.
: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``.
: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 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, binary=None):
"""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.
:param binary: ``True`` to send packet as binary, ``False`` to send
as text. If not given, unicode (Python 2) and str
(Python 3) are sent as text, and str (Python 2) and
bytes (Python 3) are sent as binary.
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(packet.Packet(packet.MESSAGE, data=data,
binary=binary))
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()
del self.sockets[sid]
else:
await asyncio.wait([client.close()
for client in six.itervalues(self.sockets)])
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)
method = environ['REQUEST_METHOD']
query = urllib.parse.parse_qs(environ.get('QUERY_STRING', ''))
sid = query['sid'][0] if 'sid' in query else None
b64 = False
jsonp = False
jsonp_index = None
if 'b64' in query:
if query['b64'][0] == "1" or query['b64'][0].lower() == "true":
b64 = True
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.logger.warning('Invalid JSONP index number')
r = self._bad_request()
elif method == 'GET':
if sid is None:
transport = query.get('transport', ['polling'])[0]
if transport != 'polling' and transport != 'websocket':
self.logger.warning('Invalid transport %s', transport)
r = self._bad_request()
else:
r = await self._handle_connect(environ, transport,
b64, jsonp_index)
else:
if sid not in self.sockets:
self.logger.warning('Invalid session %s', sid)
r = self._bad_request()
else:
socket = self._get_socket(sid)
try:
packets = await socket.handle_get_request(environ)
if isinstance(packets, list):
r = self._ok(packets, b64=b64,
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.logger.warning('Invalid session %s', sid)
r = self._bad_request()
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 r is not None else []
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
cors_headers = self._cors_headers(environ)
make_response = self._async['make_response']
if asyncio.iscoroutinefunction(make_response):
response = await make_response(r['status'],
r['headers'] + cors_headers,
r['response'], environ)
else:
response = make_response(r['status'], r['headers'] + cors_headers,
r['response'], environ)
return response
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 _handle_connect(self, environ, transport, b64=False,
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.start_background_task(self._service_task)
sid = self._generate_id()
s = asyncio_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)
ret = await self._trigger_event('connect', sid, environ,
run_async=False)
if ret is False:
del self.sockets[sid]
self.logger.warning('Application rejected connection')
return self._unauthorized()
if transport == 'websocket':
ret = await s.handle_get_request(environ)
if s.closed:
# websocket connection ended, so we are done
del self.sockets[sid]
return ret
else:
s.connected = True
headers = None
if self.cookie:
headers = [('Set-Cookie', self.cookie + '=' + sid)]
try:
return self._ok(await s.poll(), headers=headers, b64=b64,
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]) is True:
if run_async:
return self.start_background_task(self.handlers[event],
*args)
else:
try:
ret = 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
else:
if run_async:
async def async_handler():
return self.handlers[event](*args)
return self.start_background_task(async_handler)
else:
try:
ret = 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
return ret
async def _service_task(self): # pragma: no cover
"""Monitor connected clients and clean up those that time out."""
while True:
if len(self.sockets) == 0:
# nothing to do
await self.sleep(self.ping_timeout)
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 socket in self.sockets.copy().values():
if not socket.closing and not socket.closed:
await socket.check_ping_timeout()
await self.sleep(sleep_interval)
except (SystemExit, KeyboardInterrupt, asyncio.CancelledError):
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')