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29
30
31"""This file provides the opening handshake processor for the WebSocket
32protocol version HyBi 00.
33
34Specification:
35http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00
36"""
37
38
39# Note: request.connection.write/read are used in this module, even though
40# mod_python document says that they should be used only in connection
41# handlers. Unfortunately, we have no other options. For example,
42# request.write/read are not suitable because they don't allow direct raw bytes
43# writing/reading.
44
45
46import logging
47import re
48import struct
49
50from mod_pywebsocket import common
51from mod_pywebsocket.stream import StreamHixie75
52from mod_pywebsocket import util
53from mod_pywebsocket.handshake._base import HandshakeException
54from mod_pywebsocket.handshake._base import build_location
55from mod_pywebsocket.handshake._base import check_header_lines
56from mod_pywebsocket.handshake._base import format_header
57from mod_pywebsocket.handshake._base import get_mandatory_header
58from mod_pywebsocket.handshake._base import validate_subprotocol
59
60
61_MANDATORY_HEADERS = [
62    # key, expected value or None
63    [common.UPGRADE_HEADER, common.WEBSOCKET_UPGRADE_TYPE_HIXIE75],
64    [common.CONNECTION_HEADER, common.UPGRADE_CONNECTION_TYPE],
65]
66
67
68class Handshaker(object):
69    """Opening handshake processor for the WebSocket protocol version HyBi 00.
70    """
71
72    def __init__(self, request, dispatcher):
73        """Construct an instance.
74
75        Args:
76            request: mod_python request.
77            dispatcher: Dispatcher (dispatch.Dispatcher).
78
79        Handshaker will add attributes such as ws_resource in performing
80        handshake.
81        """
82
83        self._logger = util.get_class_logger(self)
84
85        self._request = request
86        self._dispatcher = dispatcher
87
88    def do_handshake(self):
89        """Perform WebSocket Handshake.
90
91        On _request, we set
92            ws_resource, ws_protocol, ws_location, ws_origin, ws_challenge,
93            ws_challenge_md5: WebSocket handshake information.
94            ws_stream: Frame generation/parsing class.
95            ws_version: Protocol version.
96
97        Raises:
98            HandshakeException: when any error happened in parsing the opening
99                                handshake request.
100        """
101
102        # 5.1 Reading the client's opening handshake.
103        # dispatcher sets it in self._request.
104        check_header_lines(self._request, _MANDATORY_HEADERS)
105        self._set_resource()
106        self._set_subprotocol()
107        self._set_location()
108        self._set_origin()
109        self._set_challenge_response()
110        self._set_protocol_version()
111
112        self._dispatcher.do_extra_handshake(self._request)
113
114        self._send_handshake()
115
116    def _set_resource(self):
117        self._request.ws_resource = self._request.uri
118
119    def _set_subprotocol(self):
120        # |Sec-WebSocket-Protocol|
121        subprotocol = self._request.headers_in.get(
122            common.SEC_WEBSOCKET_PROTOCOL_HEADER)
123        if subprotocol is not None:
124            validate_subprotocol(subprotocol, hixie=True)
125        self._request.ws_protocol = subprotocol
126
127    def _set_location(self):
128        # |Host|
129        host = self._request.headers_in.get(common.HOST_HEADER)
130        if host is not None:
131            self._request.ws_location = build_location(self._request)
132        # TODO(ukai): check host is this host.
133
134    def _set_origin(self):
135        # |Origin|
136        origin = self._request.headers_in.get(common.ORIGIN_HEADER)
137        if origin is not None:
138            self._request.ws_origin = origin
139
140    def _set_protocol_version(self):
141        # |Sec-WebSocket-Draft|
142        draft = self._request.headers_in.get(common.SEC_WEBSOCKET_DRAFT_HEADER)
143        if draft is not None and draft != '0':
144            raise HandshakeException('Illegal value for %s: %s' %
145                                     (common.SEC_WEBSOCKET_DRAFT_HEADER,
146                                      draft))
147
148        self._logger.debug('Protocol version is HyBi 00')
149        self._request.ws_version = common.VERSION_HYBI00
150        self._request.ws_stream = StreamHixie75(self._request, True)
151
152    def _set_challenge_response(self):
153        # 5.2 4-8.
154        self._request.ws_challenge = self._get_challenge()
155        # 5.2 9. let /response/ be the MD5 finterprint of /challenge/
156        self._request.ws_challenge_md5 = util.md5_hash(
157            self._request.ws_challenge).digest()
158        self._logger.debug(
159            'Challenge: %r (%s)',
160            self._request.ws_challenge,
161            util.hexify(self._request.ws_challenge))
162        self._logger.debug(
163            'Challenge response: %r (%s)',
164            self._request.ws_challenge_md5,
165            util.hexify(self._request.ws_challenge_md5))
166
167    def _get_key_value(self, key_field):
168        key_value = get_mandatory_header(self._request, key_field)
169
170        self._logger.debug('%s: %r', key_field, key_value)
171
172        # 5.2 4. let /key-number_n/ be the digits (characters in the range
173        # U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9)) in /key_n/,
174        # interpreted as a base ten integer, ignoring all other characters
175        # in /key_n/.
176        try:
177            key_number = int(re.sub("\\D", "", key_value))
178        except:
179            raise HandshakeException('%s field contains no digit' % key_field)
180        # 5.2 5. let /spaces_n/ be the number of U+0020 SPACE characters
181        # in /key_n/.
182        spaces = re.subn(" ", "", key_value)[1]
183        if spaces == 0:
184            raise HandshakeException('%s field contains no space' % key_field)
185
186        self._logger.debug(
187            '%s: Key-number is %d and number of spaces is %d',
188            key_field, key_number, spaces)
189
190        # 5.2 6. if /key-number_n/ is not an integral multiple of /spaces_n/
191        # then abort the WebSocket connection.
192        if key_number % spaces != 0:
193            raise HandshakeException(
194                '%s: Key-number (%d) is not an integral multiple of spaces '
195                '(%d)' % (key_field, key_number, spaces))
196        # 5.2 7. let /part_n/ be /key-number_n/ divided by /spaces_n/.
197        part = key_number / spaces
198        self._logger.debug('%s: Part is %d', key_field, part)
199        return part
200
201    def _get_challenge(self):
202        # 5.2 4-7.
203        key1 = self._get_key_value(common.SEC_WEBSOCKET_KEY1_HEADER)
204        key2 = self._get_key_value(common.SEC_WEBSOCKET_KEY2_HEADER)
205        # 5.2 8. let /challenge/ be the concatenation of /part_1/,
206        challenge = ''
207        challenge += struct.pack('!I', key1)  # network byteorder int
208        challenge += struct.pack('!I', key2)  # network byteorder int
209        challenge += self._request.connection.read(8)
210        return challenge
211
212    def _send_handshake(self):
213        response = []
214
215        # 5.2 10. send the following line.
216        response.append('HTTP/1.1 101 WebSocket Protocol Handshake\r\n')
217
218        # 5.2 11. send the following fields to the client.
219        response.append(format_header(
220            common.UPGRADE_HEADER, common.WEBSOCKET_UPGRADE_TYPE_HIXIE75))
221        response.append(format_header(
222            common.CONNECTION_HEADER, common.UPGRADE_CONNECTION_TYPE))
223        response.append(format_header(
224            common.SEC_WEBSOCKET_LOCATION_HEADER, self._request.ws_location))
225        response.append(format_header(
226            common.SEC_WEBSOCKET_ORIGIN_HEADER, self._request.ws_origin))
227        if self._request.ws_protocol:
228            response.append(format_header(
229                common.SEC_WEBSOCKET_PROTOCOL_HEADER,
230                self._request.ws_protocol))
231        # 5.2 12. send two bytes 0x0D 0x0A.
232        response.append('\r\n')
233        # 5.2 13. send /response/
234        response.append(self._request.ws_challenge_md5)
235
236        raw_response = ''.join(response)
237        self._request.connection.write(raw_response)
238        self._logger.debug('Sent server\'s opening handshake: %r',
239                           raw_response)
240
241
242# vi:sts=4 sw=4 et
243