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306 lines
9.4 KiB
Python
306 lines
9.4 KiB
Python
# Copyright 2011, Google Inc.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following disclaimer
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# in the documentation and/or other materials provided with the
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# distribution.
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# * Neither the name of Google Inc. nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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"""Common functions and exceptions used by WebSocket opening handshake
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processors.
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"""
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from mod_pywebsocket import common
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from mod_pywebsocket import http_header_util
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class Extension(object):
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"""Holds information about an extension which is exchanged on extension
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negotiation in opening handshake.
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"""
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def __init__(self, name):
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self._name = name
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# TODO(tyoshino): Change the data structure to more efficient one such
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# as dict when the spec changes to say like
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# - Parameter names must be unique
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# - The order of parameters is not significant
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self._parameters = []
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def name(self):
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return self._name
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def add_parameter(self, name, value):
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self._parameters.append((name, value))
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def get_parameter(self, name):
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for param_name, param_value in self._parameters:
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if param_name == name:
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return param_value
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def get_parameter_names(self):
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return [name for name, unused_value in self._parameters]
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def get_formatted_string(self):
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formatted_params = [self._name]
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for param_name, param_value in self._parameters:
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if param_value is None:
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formatted_params.append(param_name)
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else:
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quoted_value = http_header_util.quote_if_necessary(param_value)
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formatted_params.append('%s=%s' % (param_name, quoted_value))
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return '; '.join(formatted_params)
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class HandshakeError(Exception):
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"""This exception will be raised when an error occurred while processing
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WebSocket initial handshake.
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"""
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pass
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def get_default_port(is_secure):
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if is_secure:
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return common.DEFAULT_WEB_SOCKET_SECURE_PORT
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else:
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return common.DEFAULT_WEB_SOCKET_PORT
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# TODO(tyoshino): Have stricter validator for HyBi 07.
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def validate_subprotocol(subprotocol):
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"""Validate a value in subprotocol fields such as WebSocket-Protocol,
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Sec-WebSocket-Protocol.
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See
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- HyBi 06: Section 5.2.2.
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- HyBi 00: Section 4.1. Opening handshake
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- Hixie 75: Section 4.1. Handshake
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"""
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if not subprotocol:
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raise HandshakeError('Invalid subprotocol name: empty')
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for c in subprotocol:
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if not 0x20 <= ord(c) <= 0x7e:
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raise HandshakeError(
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'Illegal character in subprotocol name: %r' % c)
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def parse_host_header(request):
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fields = request.headers_in['Host'].split(':', 1)
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if len(fields) == 1:
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return fields[0], get_default_port(request.is_https())
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try:
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return fields[0], int(fields[1])
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except ValueError, e:
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raise HandshakeError('Invalid port number format: %r' % e)
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def format_header(name, value):
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return '%s: %s\r\n' % (name, value)
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def build_location(request):
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"""Build WebSocket location for request."""
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location_parts = []
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if request.is_https():
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location_parts.append(common.WEB_SOCKET_SECURE_SCHEME)
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else:
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location_parts.append(common.WEB_SOCKET_SCHEME)
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location_parts.append('://')
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host, port = parse_host_header(request)
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connection_port = request.connection.local_addr[1]
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if port != connection_port:
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raise HandshakeError('Header/connection port mismatch: %d/%d' %
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(port, connection_port))
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location_parts.append(host)
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if (port != get_default_port(request.is_https())):
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location_parts.append(':')
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location_parts.append(str(port))
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location_parts.append(request.uri)
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return ''.join(location_parts)
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def get_mandatory_header(request, key):
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value = request.headers_in.get(key)
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if value is None:
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raise HandshakeError('Header %s is not defined' % key)
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return value
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def validate_mandatory_header(request, key, expected_value):
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value = get_mandatory_header(request, key)
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if value.lower() != expected_value.lower():
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raise HandshakeError(
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'Expected %r for header %s but found %r (case-insensitive)' %
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(expected_value, key, value))
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def check_request_line(request):
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# 5.1 1. The three character UTF-8 string "GET".
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# 5.1 2. A UTF-8-encoded U+0020 SPACE character (0x20 byte).
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if request.method != 'GET':
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raise HandshakeError('Method is not GET')
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def check_header_lines(request, mandatory_headers):
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check_request_line(request)
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# The expected field names, and the meaning of their corresponding
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# values, are as follows.
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# |Upgrade| and |Connection|
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for key, expected_value in mandatory_headers:
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validate_mandatory_header(request, key, expected_value)
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def parse_token_list(data):
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"""Parses a header value which follows 1#token and returns parsed elements
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as a list of strings.
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Leading LWSes must be trimmed.
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"""
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state = http_header_util.ParsingState(data)
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token_list = []
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while True:
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token = http_header_util.consume_token(state)
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if token is not None:
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token_list.append(token)
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http_header_util.consume_lwses(state)
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if http_header_util.peek(state) is None:
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break
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if not http_header_util.consume_string(state, ','):
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raise HandshakeError(
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'Expected a comma but found %r' % http_header_util.peek(state))
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http_header_util.consume_lwses(state)
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if len(token_list) == 0:
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raise HandshakeError('No valid token found')
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return token_list
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def _parse_extension_param(state, definition):
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param_name = http_header_util.consume_token(state)
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if param_name is None:
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raise HandshakeError('No valid parameter name found')
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http_header_util.consume_lwses(state)
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if not http_header_util.consume_string(state, '='):
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definition.add_parameter(param_name, None)
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return
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http_header_util.consume_lwses(state)
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param_value = http_header_util.consume_token_or_quoted_string(state)
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if param_value is None:
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raise HandshakeError(
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'No valid parameter value found on the right-hand side of '
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'parameter %r' % param_name)
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definition.add_parameter(param_name, param_value)
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def _parse_extension(state):
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extension_token = http_header_util.consume_token(state)
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if extension_token is None:
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return None
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extension = Extension(extension_token)
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while True:
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http_header_util.consume_lwses(state)
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if not http_header_util.consume_string(state, ';'):
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break
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http_header_util.consume_lwses(state)
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try:
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_parse_extension_param(state, extension)
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except HandshakeError, e:
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raise HandshakeError(
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'Failed to parse Sec-WebSocket-Extensions header: '
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'Failed to parse parameter for %r (%r)' %
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(extension_token, e))
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return extension
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def parse_extensions(data):
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"""Parses Sec-WebSocket-Extensions header value returns a list of
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common.Extension objects.
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Leading LWSes must be trimmed.
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"""
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state = http_header_util.ParsingState(data)
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extension_list = []
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while True:
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extension = _parse_extension(state)
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if extension is not None:
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extension_list.append(extension)
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http_header_util.consume_lwses(state)
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if http_header_util.peek(state) is None:
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break
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if not http_header_util.consume_string(state, ','):
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raise HandshakeError(
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'Failed to parse Sec-WebSocket-Extensions header: '
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'Expected a comma but found %r' %
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http_header_util.peek(state))
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http_header_util.consume_lwses(state)
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if len(extension_list) == 0:
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raise HandshakeError(
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'Sec-WebSocket-Extensions header contains no valid extension')
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return extension_list
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def format_extensions(extension_list):
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formatted_extension_list = []
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for extension in extension_list:
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formatted_extension_list.append(extension.get_formatted_string())
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return ', '.join(formatted_extension_list)
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# vi:sts=4 sw=4 et
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