import gzip

import importlib

import logging

import uuid

import zlib

import six

from six.moves import urllib

from . import packet

from . import payload

from . import socket

class Server(object):

"""An Engine.IO server.

This class implements a fully compliant Engine.IO web server with support

for websocket and long-polling transports.

:param async_mode: The library used for asynchronous operations. Valid

options are "threading", "eventlet" and "gevent". If

this argument is not given, "eventlet" is tried first,

then "gevent", and finally "threading". The websocket

transport is only supported in "eventlet" mode.

: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.

"""

compression_methods = ['gzip', 'deflate']

event_names = ['connect', 'disconnect', 'message']

def __init__(self, async_mode=None, ping_timeout=60, ping_interval=25,

max_http_buffer_size=100000000, allow_upgrades=True,

http_compression=True, compression_threshold=1024,

cookie='io', cors_allowed_origins=None,

cors_credentials=True, logger=False, json=None):

self.ping_timeout = ping_timeout

self.ping_interval = ping_interval

self.max_http_buffer_size = max_http_buffer_size

self.allow_upgrades = allow_upgrades

self.http_compression = http_compression

self.compression_threshold = compression_threshold

self.cookie = cookie

self.cors_allowed_origins = cors_allowed_origins

self.cors_credentials = cors_credentials

self.sockets = {}

self.handlers = {}

if json is not None:

packet.Packet.json = json

if not isinstance(logger, bool):

self.logger = logger

else:

self.logger = logging.getLogger('engineio')

if not logging.root.handlers and \

self.logger.level == logging.NOTSET:

if logger:

self.logger.setLevel(logging.INFO)

else:

self.logger.setLevel(logging.ERROR)

self.logger.addHandler(logging.StreamHandler())

if async_mode is None:

modes = ['eventlet', 'gevent', 'threading']

else:

modes = [async_mode]

self.async = None

self.async_mode = None

for mode in modes:

try:

self.async = importlib.import_module(

'engineio.async_' + mode).async

self.async_mode = mode

break

except ImportError:

pass

if self.async_mode is None:

raise ValueError('Invalid async_mode specified')

self.logger.info('Server initialized for %s.', self.async_mode)

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(sid, environ):

print('Connection request')

if environ['REMOTE_ADDR'] in blacklisted:

return False # reject

# as a method:

def message_handler(sid, msg):

print('Received message: ', msg)

eio.send(sid, 'response')

eio.on('message', message_handler)

The handler function receives the ``sid`` (session ID) for the

client as first argument. The ``'connect'`` event handler receives the

WSGI environment as a second argument, and can return ``False`` to

reject the connection. The ``'message'`` handler receives the message

payload as a second argument. The ``'disconnect'`` handler does not

take a second argument.

"""

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 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.

"""

self._get_socket(sid).send(packet.Packet(packet.MESSAGE, data=data,

binary=binary))

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.

"""

if sid is not None:

self._get_socket(sid).close()

del self.sockets[sid]

else:

for client in six.itervalues(self.sockets):

client.close()

self.sockets = {}

def transport(self, sid):

"""Return the name of the transport used by the client.

The two possible values returned by this function are ``'polling'``

and ``'websocket'``.

:param sid: The session of the client.

"""

return 'websocket' if self._get_socket(sid).upgraded else 'polling'

def handle_request(self, environ, start_response):

"""Handle an HTTP request from the client.

This is the entry point of the Engine.IO application, using the same

interface as a WSGI application. For the typical usage, this function

is invoked by the :class:`Middleware` instance, but it can be invoked

directly when the middleware is not used.

:param environ: The WSGI environment.

:param start_response: The WSGI ``start_response`` function.

This function returns the HTTP response body to deliver to the client

as a byte sequence.

"""

method = environ['REQUEST_METHOD']

query = urllib.parse.parse_qs(environ.get('QUERY_STRING', ''))

if 'j' in query:

self.logger.warning('JSONP requests are not supported')

r = self._bad_request()

else:

sid = query['sid'][0] if 'sid' in query else None

b64 = False

if 'b64' in query:

if query['b64'][0] == "1" or query['b64'][0].lower() == "true":

b64 = True

if 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 = self._handle_connect(environ, start_response,

transport, b64)

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 = socket.handle_get_request(

environ, start_response)

r = self._ok(packets, b64=b64)

except IOError:

del self.sockets[sid]

r = self._bad_request()

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:

socket.handle_post_request(environ)

r = self._ok()

except ValueError:

r = self._bad_request()

else:

self.logger.warning('Method %s not supported', method)

r = self._method_not_found()

if self.http_compression and \

len(r['response']) >= self.compression_threshold:

encodings = [e.split(';')[0].strip() for e in

environ.get('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)

start_response(r['status'], r['headers'] + cors_headers)

return [r['response']]

def _generate_id(self):

"""Generate a unique session id."""

return uuid.uuid4().hex

def _handle_connect(self, environ, start_response, transport, b64=False):

"""Handle a client connection request."""

sid = self._generate_id()

s = socket.Socket(self, sid)

self.sockets[sid] = s

pkt = packet.Packet(

packet.OPEN, {'sid': sid,

'upgrades': self._upgrades(sid),

'pingTimeout': int(self.ping_timeout * 1000),

'pingInterval': int(self.ping_interval * 1000)})

s.send(pkt)

if self._trigger_event('connect', sid, environ) is False:

self.logger.warning('Application rejected connection')

del self.sockets[sid]

return self._unauthorized()

if transport == 'websocket':

s.handle_get_request(environ, start_response)

return self._ok()

else:

headers = None

if self.cookie:

headers = [('Set-Cookie', self.cookie + '=' + sid)]

return self._ok(s.poll(), headers=headers, b64=b64)

def _upgrades(self, sid):

"""Return the list of possible upgrades for a client connection."""

if not self.allow_upgrades or self._get_socket(sid).upgraded or \

self.async['websocket_class'] is None:

return []

return ['websocket']

def _trigger_event(self, event, *args):

"""Invoke an event handler."""

if event in self.handlers:

return self.handlers[event](*args)

def _get_socket(self, sid):

"""Return the socket object for a given session."""

try:

s = self.sockets[sid]

except KeyError:

raise KeyError('Session not found')

if s.closed:

del self.sockets[sid]

raise KeyError('Session is disconnected')

return s

def _start_background_task(self, target, *args, **kwargs):

"""Start a background task using the appropriate async model."""

return getattr(self.async['threading'],

self.async['thread_class'])(target=target, args=args,

kwargs=kwargs)

def _ok(self, packets=None, headers=None, b64=False):

"""Generate a successful HTTP response."""

if packets is not None:

if headers is None:

headers = []

headers += [('Content-Type', 'application/octet-stream')]

return {'status': '200 OK',

'headers': headers,

'response': payload.Payload(packets=packets).encode(b64)}

else:

return {'status': '200 OK',

'headers': [('Content-Type', 'text/plain')],

'response': b'OK'}

def _bad_request(self):

"""Generate a bad request HTTP error response."""

return {'status': '400 BAD REQUEST',

'headers': [('Content-Type', 'text/plain')],

'response': b'Bad Request'}

def _method_not_found(self):

"""Generate a method not found HTTP error response."""

return {'status': '405 METHOD NOT FOUND',

'headers': [('Content-Type', 'text/plain')],

'response': b'Method Not Found'}

def _unauthorized(self):

"""Generate a unauthorized HTTP error response."""

return {'status': '401 UNAUTHORIZED',

'headers': [('Content-Type', 'text/plain')],

'response': b'Unauthorized'}

def _cors_headers(self, environ):

"""Return the cross-origin-resource-sharing headers."""

if self.cors_allowed_origins is not None and \

environ.get('HTTP_ORIGIN', '') not in \

self.cors_allowed_origins:

return []

if 'HTTP_ORIGIN' in environ:

headers = [('Access-Control-Allow-Origin', environ['HTTP_ORIGIN'])]

else:

headers = [('Access-Control-Allow-Origin', '*')]

if self.cors_credentials:

headers += [('Access-Control-Allow-Credentials', 'true')]

return headers

def _gzip(self, response):

"""Apply gzip compression to a response."""

bytesio = six.BytesIO()

with gzip.GzipFile(fileobj=bytesio, mode='w') as gz:

gz.write(response)

return bytesio.getvalue()

def _deflate(self, response):

"""Apply deflate compression to a response."""

return zlib.compress(response)