| # Copyright 2012, 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 (RFC 6455). |
| |
| Specification: |
| http://tools.ietf.org/html/rfc6455 |
| """ |
| |
| |
| # 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 base64 |
| from hashlib import sha1 |
| import logging |
| import os |
| import re |
| |
| from mod_pywebsocket import common |
| from mod_pywebsocket.extensions import get_extension_processor |
| from mod_pywebsocket.extensions import is_compression_extension |
| from mod_pywebsocket.handshake._base import check_request_line |
| from mod_pywebsocket.handshake._base import format_header |
| from mod_pywebsocket.handshake._base import get_mandatory_header |
| from mod_pywebsocket.handshake._base import HandshakeException |
| from mod_pywebsocket.handshake._base import parse_token_list |
| from mod_pywebsocket.handshake._base import validate_mandatory_header |
| from mod_pywebsocket.handshake._base import validate_subprotocol |
| from mod_pywebsocket.handshake._base import VersionException |
| from mod_pywebsocket.stream import Stream |
| from mod_pywebsocket.stream import StreamOptions |
| from mod_pywebsocket import util |
| |
| |
| # Used to validate the value in the Sec-WebSocket-Key header strictly. RFC 4648 |
| # disallows non-zero padding, so the character right before == must be any of |
| # A, Q, g and w. |
| _SEC_WEBSOCKET_KEY_REGEX = re.compile('^[+/0-9A-Za-z]{21}[AQgw]==$') |
| |
| # Defining aliases for values used frequently. |
| _VERSION_LATEST = common.VERSION_HYBI_LATEST |
| _VERSION_LATEST_STRING = str(_VERSION_LATEST) |
| _SUPPORTED_VERSIONS = [ |
| _VERSION_LATEST, |
| ] |
| |
| |
| def compute_accept(key): |
| """Computes value for the Sec-WebSocket-Accept header from value of the |
| Sec-WebSocket-Key header. |
| """ |
| |
| accept_binary = sha1(key + common.WEBSOCKET_ACCEPT_UUID).digest() |
| accept = base64.b64encode(accept_binary) |
| |
| return (accept, accept_binary) |
| |
| |
| def compute_accept_from_unicode(unicode_key): |
| """A wrapper function for compute_accept which takes a unicode string as an |
| argument, and encodes it to byte string. It then passes it on to |
| compute_accept. |
| """ |
| |
| key = unicode_key.encode('UTF-8') |
| return compute_accept(key)[0] |
| |
| |
| class Handshaker(object): |
| """Opening handshake processor for the WebSocket protocol (RFC 6455).""" |
| |
| 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 during handshake. |
| """ |
| |
| self._logger = util.get_class_logger(self) |
| |
| self._request = request |
| self._dispatcher = dispatcher |
| |
| def _validate_connection_header(self): |
| connection = get_mandatory_header( |
| self._request, common.CONNECTION_HEADER) |
| |
| try: |
| connection_tokens = parse_token_list(connection) |
| except HandshakeException as e: |
| raise HandshakeException( |
| 'Failed to parse %s: %s' % (common.CONNECTION_HEADER, e)) |
| |
| connection_is_valid = False |
| for token in connection_tokens: |
| if token.lower() == common.UPGRADE_CONNECTION_TYPE.lower(): |
| connection_is_valid = True |
| break |
| if not connection_is_valid: |
| raise HandshakeException( |
| '%s header doesn\'t contain "%s"' % |
| (common.CONNECTION_HEADER, common.UPGRADE_CONNECTION_TYPE)) |
| |
| def do_handshake(self): |
| self._request.ws_close_code = None |
| self._request.ws_close_reason = None |
| |
| # Parsing. |
| |
| check_request_line(self._request) |
| |
| validate_mandatory_header( |
| self._request, |
| common.UPGRADE_HEADER, |
| common.WEBSOCKET_UPGRADE_TYPE) |
| |
| self._validate_connection_header() |
| |
| self._request.ws_resource = self._request.uri |
| |
| unused_host = get_mandatory_header(self._request, common.HOST_HEADER) |
| |
| self._request.ws_version = self._check_version() |
| |
| try: |
| self._get_origin() |
| self._set_protocol() |
| self._parse_extensions() |
| |
| # Key validation, response generation. |
| |
| key = self._get_key() |
| (accept, accept_binary) = compute_accept(key) |
| self._logger.debug( |
| '%s: %r (%s)', |
| common.SEC_WEBSOCKET_ACCEPT_HEADER, |
| accept, |
| util.hexify(accept_binary)) |
| |
| self._logger.debug('Protocol version is RFC 6455') |
| |
| # Setup extension processors. |
| |
| processors = [] |
| if self._request.ws_requested_extensions is not None: |
| for extension_request in self._request.ws_requested_extensions: |
| processor = get_extension_processor(extension_request) |
| # Unknown extension requests are just ignored. |
| if processor is not None: |
| processors.append(processor) |
| self._request.ws_extension_processors = processors |
| |
| # List of extra headers. The extra handshake handler may add header |
| # data as name/value pairs to this list and pywebsocket appends |
| # them to the WebSocket handshake. |
| self._request.extra_headers = [] |
| |
| # Extra handshake handler may modify/remove processors. |
| self._dispatcher.do_extra_handshake(self._request) |
| processors = list(filter(lambda processor: processor is not None, |
| self._request.ws_extension_processors)) |
| |
| # Ask each processor if there are extensions on the request which |
| # cannot co-exist. When processor decided other processors cannot |
| # co-exist with it, the processor marks them (or itself) as |
| # "inactive". The first extension processor has the right to |
| # make the final call. |
| for processor in reversed(processors): |
| if processor.is_active(): |
| processor.check_consistency_with_other_processors( |
| processors) |
| processors = list(filter(lambda processor: processor.is_active(), |
| processors)) |
| |
| accepted_extensions = [] |
| |
| # We need to take into account of mux extension here. |
| # If mux extension exists: |
| # - Remove processors of extensions for logical channel, |
| # which are processors located before the mux processor |
| # - Pass extension requests for logical channel to mux processor |
| # - Attach the mux processor to the request. It will be referred |
| # by dispatcher to see whether the dispatcher should use mux |
| # handler or not. |
| mux_index = -1 |
| for i, processor in enumerate(processors): |
| if processor.name() == common.MUX_EXTENSION: |
| mux_index = i |
| break |
| if mux_index >= 0: |
| logical_channel_extensions = [] |
| for processor in processors[:mux_index]: |
| logical_channel_extensions.append(processor.request()) |
| processor.set_active(False) |
| self._request.mux_processor = processors[mux_index] |
| self._request.mux_processor.set_extensions( |
| logical_channel_extensions) |
| processors = list(filter(lambda processor: processor.is_active(), |
| processors)) |
| |
| stream_options = StreamOptions() |
| |
| for index, processor in enumerate(processors): |
| if not processor.is_active(): |
| continue |
| |
| extension_response = processor.get_extension_response() |
| if extension_response is None: |
| # Rejected. |
| continue |
| |
| accepted_extensions.append(extension_response) |
| |
| processor.setup_stream_options(stream_options) |
| |
| if not is_compression_extension(processor.name()): |
| continue |
| |
| # Inactivate all of the following compression extensions. |
| for j in range(index + 1, len(processors)): |
| if is_compression_extension(processors[j].name()): |
| processors[j].set_active(False) |
| |
| if len(accepted_extensions) > 0: |
| self._request.ws_extensions = accepted_extensions |
| self._logger.debug( |
| 'Extensions accepted: %r', |
| map(common.ExtensionParameter.name, accepted_extensions)) |
| else: |
| self._request.ws_extensions = None |
| |
| self._request.ws_stream = self._create_stream(stream_options) |
| |
| if self._request.ws_requested_protocols is not None: |
| if self._request.ws_protocol is None: |
| raise HandshakeException( |
| 'do_extra_handshake must choose one subprotocol from ' |
| 'ws_requested_protocols and set it to ws_protocol') |
| validate_subprotocol(self._request.ws_protocol) |
| |
| self._logger.debug( |
| 'Subprotocol accepted: %r', |
| self._request.ws_protocol) |
| else: |
| if self._request.ws_protocol is not None: |
| raise HandshakeException( |
| 'ws_protocol must be None when the client didn\'t ' |
| 'request any subprotocol') |
| |
| self._send_handshake(accept) |
| except HandshakeException as e: |
| if not e.status: |
| # Fallback to 400 bad request by default. |
| e.status = common.HTTP_STATUS_BAD_REQUEST |
| raise e |
| |
| def _get_origin(self): |
| origin_header = common.ORIGIN_HEADER |
| origin = self._request.headers_in.get(origin_header) |
| if origin is None: |
| self._logger.debug('Client request does not have origin header') |
| self._request.ws_origin = origin |
| |
| def _check_version(self): |
| version = get_mandatory_header(self._request, |
| common.SEC_WEBSOCKET_VERSION_HEADER) |
| if version == _VERSION_LATEST_STRING: |
| return _VERSION_LATEST |
| |
| if version.find(',') >= 0: |
| raise HandshakeException( |
| 'Multiple versions (%r) are not allowed for header %s' % |
| (version, common.SEC_WEBSOCKET_VERSION_HEADER), |
| status=common.HTTP_STATUS_BAD_REQUEST) |
| raise VersionException( |
| 'Unsupported version %r for header %s' % |
| (version, common.SEC_WEBSOCKET_VERSION_HEADER), |
| supported_versions=', '.join(map(str, _SUPPORTED_VERSIONS))) |
| |
| def _set_protocol(self): |
| self._request.ws_protocol = None |
| |
| protocol_header = self._request.headers_in.get( |
| common.SEC_WEBSOCKET_PROTOCOL_HEADER) |
| |
| if protocol_header is None: |
| self._request.ws_requested_protocols = None |
| return |
| |
| self._request.ws_requested_protocols = parse_token_list( |
| protocol_header) |
| self._logger.debug('Subprotocols requested: %r', |
| self._request.ws_requested_protocols) |
| |
| def _parse_extensions(self): |
| extensions_header = self._request.headers_in.get( |
| common.SEC_WEBSOCKET_EXTENSIONS_HEADER) |
| if not extensions_header: |
| self._request.ws_requested_extensions = None |
| return |
| |
| try: |
| self._request.ws_requested_extensions = common.parse_extensions( |
| extensions_header) |
| except common.ExtensionParsingException as e: |
| raise HandshakeException( |
| 'Failed to parse Sec-WebSocket-Extensions header: %r' % e) |
| |
| self._logger.debug( |
| 'Extensions requested: %r', |
| list(map(common.ExtensionParameter.name, |
| self._request.ws_requested_extensions))) |
| |
| def _validate_key(self, key): |
| if key.find(',') >= 0: |
| raise HandshakeException('Request has multiple %s header lines or ' |
| 'contains illegal character \',\': %r' % |
| (common.SEC_WEBSOCKET_KEY_HEADER, key)) |
| |
| # Validate |
| key_is_valid = False |
| try: |
| # Validate key by quick regex match before parsing by base64 |
| # module. Because base64 module skips invalid characters, we have |
| # to do this in advance to make this server strictly reject illegal |
| # keys. |
| if _SEC_WEBSOCKET_KEY_REGEX.match(key): |
| decoded_key = base64.b64decode(key) |
| if len(decoded_key) == 16: |
| key_is_valid = True |
| except TypeError as e: |
| pass |
| |
| if not key_is_valid: |
| raise HandshakeException( |
| 'Illegal value for header %s: %r' % |
| (common.SEC_WEBSOCKET_KEY_HEADER, key)) |
| |
| return decoded_key |
| |
| def _get_key(self): |
| key = get_mandatory_header( |
| self._request, common.SEC_WEBSOCKET_KEY_HEADER) |
| |
| decoded_key = self._validate_key(key) |
| |
| self._logger.debug( |
| '%s: %r (%s)', |
| common.SEC_WEBSOCKET_KEY_HEADER, |
| key, |
| util.hexify(decoded_key)) |
| |
| return key.encode() |
| |
| def _create_stream(self, stream_options): |
| return Stream(self._request, stream_options) |
| |
| def _create_handshake_response(self, accept): |
| response = [] |
| |
| response.append('HTTP/1.1 101 Switching Protocols\r\n') |
| |
| # WebSocket headers |
| response.append(format_header( |
| common.UPGRADE_HEADER, common.WEBSOCKET_UPGRADE_TYPE)) |
| response.append(format_header( |
| common.CONNECTION_HEADER, common.UPGRADE_CONNECTION_TYPE)) |
| response.append(format_header( |
| common.SEC_WEBSOCKET_ACCEPT_HEADER, accept.decode())) |
| if self._request.ws_protocol is not None: |
| response.append(format_header( |
| common.SEC_WEBSOCKET_PROTOCOL_HEADER, |
| self._request.ws_protocol)) |
| if (self._request.ws_extensions is not None and |
| len(self._request.ws_extensions) != 0): |
| response.append(format_header( |
| common.SEC_WEBSOCKET_EXTENSIONS_HEADER, |
| common.format_extensions(self._request.ws_extensions))) |
| |
| # Headers not specific for WebSocket |
| for name, value in self._request.extra_headers: |
| response.append(format_header(name, value)) |
| |
| response.append('\r\n') |
| |
| return ''.join(response) |
| |
| def _send_handshake(self, accept): |
| raw_response = self._create_handshake_response(accept) |
| self._request.connection.write(raw_response.encode()) |
| self._logger.debug('Sent server\'s opening handshake: %r', |
| raw_response) |
| |
| |
| # vi:sts=4 sw=4 et |
