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import asyncio
import six
import sys
import time
from . import exceptions
from . import packet
from . import payload
from . import socket
class AsyncSocket(socket.Socket):
def create_queue(self):
return asyncio.Queue()
async def poll(self):
"""Wait for packets to send to the client."""
try:
packets = [await asyncio.wait_for(self.queue.get(),
self.server.ping_timeout)]
self.queue.task_done()
except (asyncio.TimeoutError, asyncio.CancelledError):
raise exceptions.QueueEmpty()
if packets == [None]:
return []
try:
packets.append(self.queue.get_nowait())
self.queue.task_done()
except asyncio.QueueEmpty:
pass
return packets
async def receive(self, pkt):
"""Receive packet from the client."""
self.server.logger.info('%s: Received packet %s data %s',
self.sid, packet.packet_names[pkt.packet_type],
pkt.data if not isinstance(pkt.data, bytes)
else '<binary>')
if pkt.packet_type == packet.PING:
self.last_ping = time.time()
await self.send(packet.Packet(packet.PONG, pkt.data))
elif pkt.packet_type == packet.MESSAGE:
await self.server._trigger_event(
'message', self.sid, pkt.data,
run_async=self.server.async_handlers)
elif pkt.packet_type == packet.UPGRADE:
await self.send(packet.Packet(packet.NOOP))
elif pkt.packet_type == packet.CLOSE:
await self.close(wait=False, abort=True)
else:
raise exceptions.UnknownPacketError()
async def check_ping_timeout(self):
"""Make sure the client is still sending pings.
This helps detect disconnections for long-polling clients.
"""
if self.closed:
raise exceptions.SocketIsClosedError()
if time.time() - self.last_ping > self.server.ping_timeout:
self.server.logger.info('%s: Client is gone, closing socket',
self.sid)
# Passing abort=False here will cause close() to write a
# CLOSE packet. This has the effect of updating half-open sockets
# to their correct state of disconnected
await self.close(wait=False, abort=False)
return False
return True
async def send(self, pkt):
"""Send a packet to the client."""
if not await self.check_ping_timeout():
return
self.server.logger.info('%s: Sending packet %s data %s',
self.sid, packet.packet_names[pkt.packet_type],
pkt.data if not isinstance(pkt.data, bytes)
else '<binary>')
await self.queue.put(pkt)
async def handle_get_request(self, environ):
"""Handle a long-polling GET request from the client."""
connections = [
s.strip()
for s in environ.get('HTTP_CONNECTION', '').lower().split(',')]
transport = environ.get('HTTP_UPGRADE', '').lower()
if 'upgrade' in connections and transport in self.upgrade_protocols:
self.server.logger.info('%s: Received request to upgrade to %s',
self.sid, transport)
return await getattr(self, '_upgrade_' + transport)(environ)
try:
packets = await self.poll()
except exceptions.QueueEmpty:
exc = sys.exc_info()
await self.close(wait=False)
six.reraise(*exc)
return packets
async def handle_post_request(self, environ):
"""Handle a long-polling POST request from the client."""
length = int(environ.get('CONTENT_LENGTH', '0'))
if length > self.server.max_http_buffer_size:
raise exceptions.ContentTooLongError()
else:
body = await environ['wsgi.input'].read(length)
p = payload.Payload(encoded_payload=body)
for pkt in p.packets:
await self.receive(pkt)
async def close(self, wait=True, abort=False):
"""Close the socket connection."""
if not self.closed and not self.closing:
self.closing = True
await self.server._trigger_event('disconnect', self.sid)
if not abort:
await self.send(packet.Packet(packet.CLOSE))
self.closed = True
if wait:
await self.queue.join()
async def _upgrade_websocket(self, environ):
"""Upgrade the connection from polling to websocket."""
if self.upgraded:
raise IOError('Socket has been upgraded already')
if self.server._async['websocket'] is None or \
self.server._async['websocket_class'] is None:
# the selected async mode does not support websocket
return self.server._bad_request()
websocket_class = getattr(self.server._async['websocket'],
self.server._async['websocket_class'])
ws = websocket_class(self._websocket_handler)
return await ws(environ)
async def _websocket_handler(self, ws):
"""Engine.IO handler for websocket transport."""
if self.connected:
# the socket was already connected, so this is an upgrade
await self.queue.join() # flush the queue first
try:
pkt = await ws.wait()
except IOError: # pragma: no cover
return
if pkt != packet.Packet(packet.PING,
data=six.text_type('probe')).encode(
always_bytes=False):
self.server.logger.info(
'%s: Failed websocket upgrade, no PING packet', self.sid)
return
await ws.send(packet.Packet(
packet.PONG,
data=six.text_type('probe')).encode(always_bytes=False))
await self.send(packet.Packet(packet.NOOP))
try:
pkt = await ws.wait()
except IOError: # pragma: no cover
return
decoded_pkt = packet.Packet(encoded_packet=pkt)
if decoded_pkt.packet_type != packet.UPGRADE:
self.upgraded = False
self.server.logger.info(
('%s: Failed websocket upgrade, expected UPGRADE packet, '
'received %s instead.'),
self.sid, pkt)
return
self.upgraded = True
else:
self.connected = True
self.upgraded = True
# start separate writer thread
async def writer():
while True:
packets = None
try:
packets = await self.poll()
except exceptions.QueueEmpty:
break
if not packets:
# empty packet list returned -> connection closed
break
try:
for pkt in packets:
await ws.send(pkt.encode(always_bytes=False))
except:
break
writer_task = asyncio.ensure_future(writer())
self.server.logger.info(
'%s: Upgrade to websocket successful', self.sid)
while True:
p = None
wait_task = asyncio.ensure_future(ws.wait())
try:
p = await asyncio.wait_for(wait_task, self.server.ping_timeout)
except asyncio.CancelledError: # pragma: no cover
# there is a bug (https://bugs.python.org/issue30508) in
# asyncio that causes a "Task exception never retrieved" error
# to appear when wait_task raises an exception before it gets
# cancelled. Calling wait_task.exception() prevents the error
# from being issued in Python 3.6, but causes other errors in
# other versions, so we run it with all errors suppressed and
# hope for the best.
try:
wait_task.exception()
except:
pass
break
except:
break
if p is None:
# connection closed by client
break
if isinstance(p, six.text_type): # pragma: no cover
p = p.encode('utf-8')
pkt = packet.Packet(encoded_packet=p)
try:
await self.receive(pkt)
except exceptions.UnknownPacketError: # pragma: no cover
pass
except exceptions.SocketIsClosedError: # pragma: no cover
self.server.logger.info('Receive error -- socket is closed')
break
except: # pragma: no cover
# if we get an unexpected exception we log the error and exit
# the connection properly
self.server.logger.exception('Unknown receive error')
await self.queue.put(None) # unlock the writer task so it can exit
await asyncio.wait_for(writer_task, timeout=None)
await self.close(wait=False, abort=True)
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