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"""WebSocket handshaking defined in draft-hixie-thewebsocketprotocol-75."""
# Note: request.connection.write is used in this module, even though mod_python
# document says that it should be used only in connection handlers.
# Unfortunately, we have no other options. For example, request.write is not
# suitable because it doesn't allow direct raw bytes writing.
import logging
import re
from mod_pywebsocket import common
from mod_pywebsocket.stream import StreamHixie75
from mod_pywebsocket import util
from mod_pywebsocket.handshake._base import HandshakeException
from mod_pywebsocket.handshake._base import build_location
from mod_pywebsocket.handshake._base import validate_subprotocol
_MANDATORY_HEADERS = [
# key, expected value or None
['Upgrade', 'WebSocket'],
['Connection', 'Upgrade'],
['Host', None],
['Origin', None],
]
_FIRST_FIVE_LINES = map(re.compile, [
r'^GET /[\S]* HTTP/1.1\r\n$',
r'^Upgrade: WebSocket\r\n$',
r'^Connection: Upgrade\r\n$',
r'^Host: [\S]+\r\n$',
r'^Origin: [\S]+\r\n$',
])
_SIXTH_AND_LATER = re.compile(
r'^'
r'(WebSocket-Protocol: [\x20-\x7e]+\r\n)?'
r'(Cookie: [^\r]*\r\n)*'
r'(Cookie2: [^\r]*\r\n)?'
r'(Cookie: [^\r]*\r\n)*'
r'\r\n')
class Handshaker(object):
"""This class performs WebSocket handshake."""
def __init__(self, request, dispatcher, strict=False):
"""Construct an instance.
Args:
request: mod_python request.
dispatcher: Dispatcher (dispatch.Dispatcher).
strict: Strictly check handshake request. Default: False.
If True, request.connection must provide get_memorized_lines
method.
Handshaker will add attributes such as ws_resource in performing
handshake.
"""
self._logger = util.get_class_logger(self)
self._request = request
self._dispatcher = dispatcher
self._strict = strict
def do_handshake(self):
"""Perform WebSocket Handshake.
On _request, we set
ws_resource, ws_origin, ws_location, ws_protocol
ws_challenge_md5: WebSocket handshake information.
ws_stream: Frame generation/parsing class.
ws_version: Protocol version.
"""
self._check_header_lines()
self._set_resource()
self._set_origin()
self._set_location()
self._set_subprotocol()
self._set_protocol_version()
self._dispatcher.do_extra_handshake(self._request)
self._send_handshake()
self._logger.debug('Sent opening handshake response')
def _set_resource(self):
self._request.ws_resource = self._request.uri
def _set_origin(self):
self._request.ws_origin = self._request.headers_in['Origin']
def _set_location(self):
self._request.ws_location = build_location(self._request)
def _set_subprotocol(self):
subprotocol = self._request.headers_in.get('WebSocket-Protocol')
if subprotocol is not None:
validate_subprotocol(subprotocol, hixie=True)
self._request.ws_protocol = subprotocol
def _set_protocol_version(self):
self._logger.debug('IETF Hixie 75 protocol')
self._request.ws_version = common.VERSION_HIXIE75
self._request.ws_stream = StreamHixie75(self._request)
def _sendall(self, data):
self._request.connection.write(data)
def _send_handshake(self):
self._sendall('HTTP/1.1 101 Web Socket Protocol Handshake\r\n')
self._sendall('Upgrade: WebSocket\r\n')
self._sendall('Connection: Upgrade\r\n')
self._sendall('WebSocket-Origin: %s\r\n' % self._request.ws_origin)
self._sendall('WebSocket-Location: %s\r\n' % self._request.ws_location)
if self._request.ws_protocol:
self._sendall(
'WebSocket-Protocol: %s\r\n' % self._request.ws_protocol)
self._sendall('\r\n')
def _check_header_lines(self):
for key, expected_value in _MANDATORY_HEADERS:
actual_value = self._request.headers_in.get(key)
if not actual_value:
raise HandshakeException('Header %s is not defined' % key)
if expected_value:
if actual_value != expected_value:
raise HandshakeException(
'Expected %r for header %s but found %r' %
(expected_value, key, actual_value))
if self._strict:
try:
lines = self._request.connection.get_memorized_lines()
except AttributeError, e:
raise AttributeError(
'Strict handshake is specified but the connection '
'doesn\'t provide get_memorized_lines()')
self._check_first_lines(lines)
def _check_first_lines(self, lines):
if len(lines) < len(_FIRST_FIVE_LINES):
raise HandshakeException('Too few header lines: %d' % len(lines))
for line, regexp in zip(lines, _FIRST_FIVE_LINES):
if not regexp.search(line):
raise HandshakeException(
'Unexpected header: %r doesn\'t match %r'
% (line, regexp.pattern))
sixth_and_later = ''.join(lines[5:])
if not _SIXTH_AND_LATER.search(sixth_and_later):
raise HandshakeException(
'Unexpected header: %r doesn\'t match %r'
% (sixth_and_later, _SIXTH_AND_LATER.pattern))
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