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 '<binary>')
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 '<binary>')
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')