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# Copyright 2011, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""This file provides the opening handshake processor for the WebSocket
protocol version HyBi 00.
Specification:
http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00
"""
# Note: request.connection.write/read are used in this module, even though
# mod_python document says that they should be used only in connection
# handlers. Unfortunately, we have no other options. For example,
# request.write/read are not suitable because they don't allow direct raw bytes
# writing/reading.
import logging
import re
import struct
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 check_request_line
from mod_pywebsocket.handshake._base import format_header
from mod_pywebsocket.handshake._base import get_default_port
from mod_pywebsocket.handshake._base import get_mandatory_header
from mod_pywebsocket.handshake._base import parse_host_header
from mod_pywebsocket.handshake._base import validate_mandatory_header
_MANDATORY_HEADERS = [
# key, expected value or None
[common.UPGRADE_HEADER, common.WEBSOCKET_UPGRADE_TYPE_HIXIE75],
[common.CONNECTION_HEADER, common.UPGRADE_CONNECTION_TYPE],
]
def _validate_subprotocol(subprotocol):
"""Checks if characters in subprotocol are in range between U+0020 and
U+007E. A value in the Sec-WebSocket-Protocol field need to satisfy this
requirement.
See the Section 4.1. Opening handshake of the spec.
"""
if not subprotocol:
raise HandshakeException('Invalid subprotocol name: empty')
# Parameter should be in the range U+0020 to U+007E.
for c in subprotocol:
if not 0x20 <= ord(c) <= 0x7e:
raise HandshakeException(
'Illegal character in subprotocol name: %r' % c)
def _check_header_lines(request, mandatory_headers):
check_request_line(request)
# The expected field names, and the meaning of their corresponding
# values, are as follows.
# |Upgrade| and |Connection|
for key, expected_value in mandatory_headers:
validate_mandatory_header(request, key, expected_value)
def _build_location(request):
"""Build WebSocket location for request."""
location_parts = []
if request.is_https():
location_parts.append(common.WEB_SOCKET_SECURE_SCHEME)
else:
location_parts.append(common.WEB_SOCKET_SCHEME)
location_parts.append('://')
host, port = parse_host_header(request)
connection_port = request.connection.local_addr[1]
if port != connection_port:
raise HandshakeException('Header/connection port mismatch: %d/%d' %
(port, connection_port))
location_parts.append(host)
if (port != get_default_port(request.is_https())):
location_parts.append(':')
location_parts.append(str(port))
location_parts.append(request.unparsed_uri)
return ''.join(location_parts)
class Handshaker(object):
"""Opening handshake processor for the WebSocket protocol version HyBi 00.
"""
def __init__(self, request, dispatcher):
"""Construct an instance.
Args:
request: mod_python request.
dispatcher: Dispatcher (dispatch.Dispatcher).
Handshaker will add attributes such as ws_resource in performing
handshake.
"""
self._logger = util.get_class_logger(self)
self._request = request
self._dispatcher = dispatcher
def do_handshake(self):
"""Perform WebSocket Handshake.
On _request, we set
ws_resource, ws_protocol, ws_location, ws_origin, ws_challenge,
ws_challenge_md5: WebSocket handshake information.
ws_stream: Frame generation/parsing class.
ws_version: Protocol version.
Raises:
HandshakeException: when any error happened in parsing the opening
handshake request.
"""
# 5.1 Reading the client's opening handshake.
# dispatcher sets it in self._request.
_check_header_lines(self._request, _MANDATORY_HEADERS)
self._set_resource()
self._set_subprotocol()
self._set_location()
self._set_origin()
self._set_challenge_response()
self._set_protocol_version()
self._dispatcher.do_extra_handshake(self._request)
self._send_handshake()
def _set_resource(self):
self._request.ws_resource = self._request.uri
def _set_subprotocol(self):
# |Sec-WebSocket-Protocol|
subprotocol = self._request.headers_in.get(
common.SEC_WEBSOCKET_PROTOCOL_HEADER)
if subprotocol is not None:
_validate_subprotocol(subprotocol)
self._request.ws_protocol = subprotocol
def _set_location(self):
# |Host|
host = self._request.headers_in.get(common.HOST_HEADER)
if host is not None:
self._request.ws_location = _build_location(self._request)
# TODO(ukai): check host is this host.
def _set_origin(self):
# |Origin|
origin = self._request.headers_in.get(common.ORIGIN_HEADER)
if origin is not None:
self._request.ws_origin = origin
def _set_protocol_version(self):
# |Sec-WebSocket-Draft|
draft = self._request.headers_in.get(common.SEC_WEBSOCKET_DRAFT_HEADER)
if draft is not None and draft != '0':
raise HandshakeException('Illegal value for %s: %s' %
(common.SEC_WEBSOCKET_DRAFT_HEADER,
draft))
self._logger.debug('Protocol version is HyBi 00')
self._request.ws_version = common.VERSION_HYBI00
self._request.ws_stream = StreamHixie75(self._request, True)
def _set_challenge_response(self):
# 5.2 4-8.
self._request.ws_challenge = self._get_challenge()
# 5.2 9. let /response/ be the MD5 finterprint of /challenge/
self._request.ws_challenge_md5 = util.md5_hash(
self._request.ws_challenge).digest()
self._logger.debug(
'Challenge: %r (%s)',
self._request.ws_challenge,
util.hexify(self._request.ws_challenge))
self._logger.debug(
'Challenge response: %r (%s)',
self._request.ws_challenge_md5,
util.hexify(self._request.ws_challenge_md5))
def _get_key_value(self, key_field):
key_value = get_mandatory_header(self._request, key_field)
self._logger.debug('%s: %r', key_field, key_value)
# 5.2 4. let /key-number_n/ be the digits (characters in the range
# U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9)) in /key_n/,
# interpreted as a base ten integer, ignoring all other characters
# in /key_n/.
try:
key_number = int(re.sub("\\D", "", key_value))
except:
raise HandshakeException('%s field contains no digit' % key_field)
# 5.2 5. let /spaces_n/ be the number of U+0020 SPACE characters
# in /key_n/.
spaces = re.subn(" ", "", key_value)[1]
if spaces == 0:
raise HandshakeException('%s field contains no space' % key_field)
self._logger.debug(
'%s: Key-number is %d and number of spaces is %d',
key_field, key_number, spaces)
# 5.2 6. if /key-number_n/ is not an integral multiple of /spaces_n/
# then abort the WebSocket connection.
if key_number % spaces != 0:
raise HandshakeException(
'%s: Key-number (%d) is not an integral multiple of spaces '
'(%d)' % (key_field, key_number, spaces))
# 5.2 7. let /part_n/ be /key-number_n/ divided by /spaces_n/.
part = key_number / spaces
self._logger.debug('%s: Part is %d', key_field, part)
return part
def _get_challenge(self):
# 5.2 4-7.
key1 = self._get_key_value(common.SEC_WEBSOCKET_KEY1_HEADER)
key2 = self._get_key_value(common.SEC_WEBSOCKET_KEY2_HEADER)
# 5.2 8. let /challenge/ be the concatenation of /part_1/,
challenge = ''
challenge += struct.pack('!I', key1) # network byteorder int
challenge += struct.pack('!I', key2) # network byteorder int
challenge += self._request.connection.read(8)
return challenge
def _send_handshake(self):
response = []
# 5.2 10. send the following line.
response.append('HTTP/1.1 101 WebSocket Protocol Handshake\r\n')
# 5.2 11. send the following fields to the client.
response.append(format_header(
common.UPGRADE_HEADER, common.WEBSOCKET_UPGRADE_TYPE_HIXIE75))
response.append(format_header(
common.CONNECTION_HEADER, common.UPGRADE_CONNECTION_TYPE))
response.append(format_header(
common.SEC_WEBSOCKET_LOCATION_HEADER, self._request.ws_location))
response.append(format_header(
common.SEC_WEBSOCKET_ORIGIN_HEADER, self._request.ws_origin))
if self._request.ws_protocol:
response.append(format_header(
common.SEC_WEBSOCKET_PROTOCOL_HEADER,
self._request.ws_protocol))
# 5.2 12. send two bytes 0x0D 0x0A.
response.append('\r\n')
# 5.2 13. send /response/
response.append(self._request.ws_challenge_md5)
raw_response = ''.join(response)
self._request.connection.write(raw_response)
self._logger.debug('Sent server\'s opening handshake: %r',
raw_response)
# vi:sts=4 sw=4 et
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