/usr/share/pyshared/eventlet/websocket.py is in python-eventlet 0.9.16-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import errno
import string
import struct
from socket import error as SocketError
try:
from hashlib import md5
except ImportError: #pragma NO COVER
from md5 import md5
import eventlet
from eventlet import semaphore
from eventlet import wsgi
from eventlet.green import socket
from eventlet.support import get_errno
ACCEPTABLE_CLIENT_ERRORS = set((errno.ECONNRESET, errno.EPIPE))
__all__ = ["WebSocketWSGI", "WebSocket"]
class WebSocketWSGI(object):
"""Wraps a websocket handler function in a WSGI application.
Use it like this::
@websocket.WebSocketWSGI
def my_handler(ws):
from_browser = ws.wait()
ws.send("from server")
The single argument to the function will be an instance of
:class:`WebSocket`. To close the socket, simply return from the
function. Note that the server will log the websocket request at
the time of closure.
"""
def __init__(self, handler):
self.handler = handler
self.protocol_version = None
def __call__(self, environ, start_response):
if not (environ.get('HTTP_CONNECTION') == 'Upgrade' and
environ.get('HTTP_UPGRADE') == 'WebSocket'):
# need to check a few more things here for true compliance
start_response('400 Bad Request', [('Connection','close')])
return []
# See if they sent the new-format headers
if 'HTTP_SEC_WEBSOCKET_KEY1' in environ:
self.protocol_version = 76
if 'HTTP_SEC_WEBSOCKET_KEY2' not in environ:
# That's bad.
start_response('400 Bad Request', [('Connection','close')])
return []
else:
self.protocol_version = 75
# Get the underlying socket and wrap a WebSocket class around it
sock = environ['eventlet.input'].get_socket()
ws = WebSocket(sock, environ, self.protocol_version)
# If it's new-version, we need to work out our challenge response
if self.protocol_version == 76:
key1 = self._extract_number(environ['HTTP_SEC_WEBSOCKET_KEY1'])
key2 = self._extract_number(environ['HTTP_SEC_WEBSOCKET_KEY2'])
# There's no content-length header in the request, but it has 8
# bytes of data.
environ['wsgi.input'].content_length = 8
key3 = environ['wsgi.input'].read(8)
key = struct.pack(">II", key1, key2) + key3
response = md5(key).digest()
# Start building the response
scheme = 'ws'
if environ.get('wsgi.url_scheme') == 'https':
scheme = 'wss'
location = '%s://%s%s%s' % (
scheme,
environ.get('HTTP_HOST'),
environ.get('SCRIPT_NAME'),
environ.get('PATH_INFO')
)
qs = environ.get('QUERY_STRING')
if qs is not None:
location += '?' + qs
if self.protocol_version == 75:
handshake_reply = ("HTTP/1.1 101 Web Socket Protocol Handshake\r\n"
"Upgrade: WebSocket\r\n"
"Connection: Upgrade\r\n"
"WebSocket-Origin: %s\r\n"
"WebSocket-Location: %s\r\n\r\n" % (
environ.get('HTTP_ORIGIN'),
location))
elif self.protocol_version == 76:
handshake_reply = ("HTTP/1.1 101 WebSocket Protocol Handshake\r\n"
"Upgrade: WebSocket\r\n"
"Connection: Upgrade\r\n"
"Sec-WebSocket-Origin: %s\r\n"
"Sec-WebSocket-Protocol: %s\r\n"
"Sec-WebSocket-Location: %s\r\n"
"\r\n%s"% (
environ.get('HTTP_ORIGIN'),
environ.get('HTTP_SEC_WEBSOCKET_PROTOCOL', 'default'),
location,
response))
else: #pragma NO COVER
raise ValueError("Unknown WebSocket protocol version.")
sock.sendall(handshake_reply)
try:
self.handler(ws)
except socket.error, e:
if get_errno(e) not in ACCEPTABLE_CLIENT_ERRORS:
raise
# Make sure we send the closing frame
ws._send_closing_frame(True)
# use this undocumented feature of eventlet.wsgi to ensure that it
# doesn't barf on the fact that we didn't call start_response
return wsgi.ALREADY_HANDLED
def _extract_number(self, value):
"""
Utility function which, given a string like 'g98sd 5[]221@1', will
return 9852211. Used to parse the Sec-WebSocket-Key headers.
"""
out = ""
spaces = 0
for char in value:
if char in string.digits:
out += char
elif char == " ":
spaces += 1
return int(out) / spaces
class WebSocket(object):
"""A websocket object that handles the details of
serialization/deserialization to the socket.
The primary way to interact with a :class:`WebSocket` object is to
call :meth:`send` and :meth:`wait` in order to pass messages back
and forth with the browser. Also available are the following
properties:
path
The path value of the request. This is the same as the WSGI PATH_INFO variable, but more convenient.
protocol
The value of the Websocket-Protocol header.
origin
The value of the 'Origin' header.
environ
The full WSGI environment for this request.
"""
def __init__(self, sock, environ, version=76):
"""
:param socket: The eventlet socket
:type socket: :class:`eventlet.greenio.GreenSocket`
:param environ: The wsgi environment
:param version: The WebSocket spec version to follow (default is 76)
"""
self.socket = sock
self.origin = environ.get('HTTP_ORIGIN')
self.protocol = environ.get('HTTP_WEBSOCKET_PROTOCOL')
self.path = environ.get('PATH_INFO')
self.environ = environ
self.version = version
self.websocket_closed = False
self._buf = ""
self._msgs = collections.deque()
self._sendlock = semaphore.Semaphore()
@staticmethod
def _pack_message(message):
"""Pack the message inside ``00`` and ``FF``
As per the dataframing section (5.3) for the websocket spec
"""
if isinstance(message, unicode):
message = message.encode('utf-8')
elif not isinstance(message, str):
message = str(message)
packed = "\x00%s\xFF" % message
return packed
def _parse_messages(self):
""" Parses for messages in the buffer *buf*. It is assumed that
the buffer contains the start character for a message, but that it
may contain only part of the rest of the message.
Returns an array of messages, and the buffer remainder that
didn't contain any full messages."""
msgs = []
end_idx = 0
buf = self._buf
while buf:
frame_type = ord(buf[0])
if frame_type == 0:
# Normal message.
end_idx = buf.find("\xFF")
if end_idx == -1: #pragma NO COVER
break
msgs.append(buf[1:end_idx].decode('utf-8', 'replace'))
buf = buf[end_idx+1:]
elif frame_type == 255:
# Closing handshake.
assert ord(buf[1]) == 0, "Unexpected closing handshake: %r" % buf
self.websocket_closed = True
break
else:
raise ValueError("Don't understand how to parse this type of message: %r" % buf)
self._buf = buf
return msgs
def send(self, message):
"""Send a message to the browser.
*message* should be convertable to a string; unicode objects should be
encodable as utf-8. Raises socket.error with errno of 32
(broken pipe) if the socket has already been closed by the client."""
packed = self._pack_message(message)
# if two greenthreads are trying to send at the same time
# on the same socket, sendlock prevents interleaving and corruption
self._sendlock.acquire()
try:
self.socket.sendall(packed)
finally:
self._sendlock.release()
def wait(self):
"""Waits for and deserializes messages.
Returns a single message; the oldest not yet processed. If the client
has already closed the connection, returns None. This is different
from normal socket behavior because the empty string is a valid
websocket message."""
while not self._msgs:
# Websocket might be closed already.
if self.websocket_closed:
return None
# no parsed messages, must mean buf needs more data
delta = self.socket.recv(8096)
if delta == '':
return None
self._buf += delta
msgs = self._parse_messages()
self._msgs.extend(msgs)
return self._msgs.popleft()
def _send_closing_frame(self, ignore_send_errors=False):
"""Sends the closing frame to the client, if required."""
if self.version == 76 and not self.websocket_closed:
try:
self.socket.sendall("\xff\x00")
except SocketError:
# Sometimes, like when the remote side cuts off the connection,
# we don't care about this.
if not ignore_send_errors: #pragma NO COVER
raise
self.websocket_closed = True
def close(self):
"""Forcibly close the websocket; generally it is preferable to
return from the handler method."""
self._send_closing_frame()
self.socket.shutdown(True)
self.socket.close()
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