474 lines
18 KiB
Python
474 lines
18 KiB
Python
# Copyright 2012, 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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from __future__ import absolute_import
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from mod_pywebsocket import common
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from mod_pywebsocket import util
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from mod_pywebsocket.http_header_util import quote_if_necessary
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# The list of available server side extension processor classes.
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_available_processors = {}
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class ExtensionProcessorInterface(object):
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def __init__(self, request):
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self._logger = util.get_class_logger(self)
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self._request = request
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self._active = True
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def request(self):
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return self._request
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def name(self):
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return None
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def check_consistency_with_other_processors(self, processors):
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pass
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def set_active(self, active):
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self._active = active
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def is_active(self):
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return self._active
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def _get_extension_response_internal(self):
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return None
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def get_extension_response(self):
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if not self._active:
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self._logger.debug('Extension %s is deactivated', self.name())
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return None
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response = self._get_extension_response_internal()
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if response is None:
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self._active = False
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return response
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def _setup_stream_options_internal(self, stream_options):
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pass
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def setup_stream_options(self, stream_options):
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if self._active:
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self._setup_stream_options_internal(stream_options)
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def _log_outgoing_compression_ratio(logger, original_bytes, filtered_bytes,
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average_ratio):
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# Print inf when ratio is not available.
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ratio = float('inf')
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if original_bytes != 0:
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ratio = float(filtered_bytes) / original_bytes
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logger.debug('Outgoing compression ratio: %f (average: %f)' %
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(ratio, average_ratio))
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def _log_incoming_compression_ratio(logger, received_bytes, filtered_bytes,
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average_ratio):
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# Print inf when ratio is not available.
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ratio = float('inf')
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if filtered_bytes != 0:
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ratio = float(received_bytes) / filtered_bytes
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logger.debug('Incoming compression ratio: %f (average: %f)' %
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(ratio, average_ratio))
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def _parse_window_bits(bits):
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"""Return parsed integer value iff the given string conforms to the
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grammar of the window bits extension parameters.
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"""
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if bits is None:
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raise ValueError('Value is required')
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# For non integer values such as "10.0", ValueError will be raised.
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int_bits = int(bits)
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# First condition is to drop leading zero case e.g. "08".
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if bits != str(int_bits) or int_bits < 8 or int_bits > 15:
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raise ValueError('Invalid value: %r' % bits)
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return int_bits
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class _AverageRatioCalculator(object):
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"""Stores total bytes of original and result data, and calculates average
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result / original ratio.
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"""
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def __init__(self):
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self._total_original_bytes = 0
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self._total_result_bytes = 0
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def add_original_bytes(self, value):
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self._total_original_bytes += value
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def add_result_bytes(self, value):
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self._total_result_bytes += value
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def get_average_ratio(self):
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if self._total_original_bytes != 0:
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return (float(self._total_result_bytes) /
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self._total_original_bytes)
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else:
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return float('inf')
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class PerMessageDeflateExtensionProcessor(ExtensionProcessorInterface):
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"""permessage-deflate extension processor.
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Specification:
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http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-08
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"""
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_SERVER_MAX_WINDOW_BITS_PARAM = 'server_max_window_bits'
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_SERVER_NO_CONTEXT_TAKEOVER_PARAM = 'server_no_context_takeover'
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_CLIENT_MAX_WINDOW_BITS_PARAM = 'client_max_window_bits'
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_CLIENT_NO_CONTEXT_TAKEOVER_PARAM = 'client_no_context_takeover'
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def __init__(self, request):
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"""Construct PerMessageDeflateExtensionProcessor."""
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ExtensionProcessorInterface.__init__(self, request)
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self._logger = util.get_class_logger(self)
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self._preferred_client_max_window_bits = None
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self._client_no_context_takeover = False
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def name(self):
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# This method returns "deflate" (not "permessage-deflate") for
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# compatibility.
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return 'deflate'
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def _get_extension_response_internal(self):
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for name in self._request.get_parameter_names():
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if name not in [
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self._SERVER_MAX_WINDOW_BITS_PARAM,
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self._SERVER_NO_CONTEXT_TAKEOVER_PARAM,
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self._CLIENT_MAX_WINDOW_BITS_PARAM
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]:
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self._logger.debug('Unknown parameter: %r', name)
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return None
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server_max_window_bits = None
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if self._request.has_parameter(self._SERVER_MAX_WINDOW_BITS_PARAM):
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server_max_window_bits = self._request.get_parameter_value(
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self._SERVER_MAX_WINDOW_BITS_PARAM)
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try:
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server_max_window_bits = _parse_window_bits(
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server_max_window_bits)
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except ValueError as e:
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self._logger.debug('Bad %s parameter: %r',
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self._SERVER_MAX_WINDOW_BITS_PARAM, e)
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return None
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server_no_context_takeover = self._request.has_parameter(
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self._SERVER_NO_CONTEXT_TAKEOVER_PARAM)
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if (server_no_context_takeover and self._request.get_parameter_value(
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self._SERVER_NO_CONTEXT_TAKEOVER_PARAM) is not None):
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self._logger.debug('%s parameter must not have a value: %r',
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self._SERVER_NO_CONTEXT_TAKEOVER_PARAM,
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server_no_context_takeover)
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return None
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# client_max_window_bits from a client indicates whether the client can
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# accept client_max_window_bits from a server or not.
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client_client_max_window_bits = self._request.has_parameter(
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self._CLIENT_MAX_WINDOW_BITS_PARAM)
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if (client_client_max_window_bits
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and self._request.get_parameter_value(
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self._CLIENT_MAX_WINDOW_BITS_PARAM) is not None):
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self._logger.debug(
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'%s parameter must not have a value in a '
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'client\'s opening handshake: %r',
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self._CLIENT_MAX_WINDOW_BITS_PARAM,
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client_client_max_window_bits)
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return None
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self._rfc1979_deflater = util._RFC1979Deflater(
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server_max_window_bits, server_no_context_takeover)
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# Note that we prepare for incoming messages compressed with window
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# bits upto 15 regardless of the client_max_window_bits value to be
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# sent to the client.
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self._rfc1979_inflater = util._RFC1979Inflater()
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self._framer = _PerMessageDeflateFramer(server_max_window_bits,
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server_no_context_takeover)
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self._framer.set_bfinal(False)
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self._framer.set_compress_outgoing_enabled(True)
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response = common.ExtensionParameter(self._request.name())
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if server_max_window_bits is not None:
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response.add_parameter(self._SERVER_MAX_WINDOW_BITS_PARAM,
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str(server_max_window_bits))
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if server_no_context_takeover:
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response.add_parameter(self._SERVER_NO_CONTEXT_TAKEOVER_PARAM,
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None)
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if self._preferred_client_max_window_bits is not None:
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if not client_client_max_window_bits:
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self._logger.debug(
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'Processor is configured to use %s but '
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'the client cannot accept it',
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self._CLIENT_MAX_WINDOW_BITS_PARAM)
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return None
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response.add_parameter(self._CLIENT_MAX_WINDOW_BITS_PARAM,
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str(self._preferred_client_max_window_bits))
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if self._client_no_context_takeover:
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response.add_parameter(self._CLIENT_NO_CONTEXT_TAKEOVER_PARAM,
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None)
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self._logger.debug('Enable %s extension ('
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'request: server_max_window_bits=%s; '
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'server_no_context_takeover=%r, '
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'response: client_max_window_bits=%s; '
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'client_no_context_takeover=%r)' %
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(self._request.name(), server_max_window_bits,
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server_no_context_takeover,
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self._preferred_client_max_window_bits,
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self._client_no_context_takeover))
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return response
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def _setup_stream_options_internal(self, stream_options):
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self._framer.setup_stream_options(stream_options)
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def set_client_max_window_bits(self, value):
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"""If this option is specified, this class adds the
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client_max_window_bits extension parameter to the handshake response,
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but doesn't reduce the LZ77 sliding window size of its inflater.
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I.e., you can use this for testing client implementation but cannot
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reduce memory usage of this class.
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If this method has been called with True and an offer without the
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client_max_window_bits extension parameter is received,
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- (When processing the permessage-deflate extension) this processor
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declines the request.
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- (When processing the permessage-compress extension) this processor
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accepts the request.
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"""
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self._preferred_client_max_window_bits = value
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def set_client_no_context_takeover(self, value):
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"""If this option is specified, this class adds the
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client_no_context_takeover extension parameter to the handshake
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response, but doesn't reset inflater for each message. I.e., you can
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use this for testing client implementation but cannot reduce memory
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usage of this class.
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"""
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self._client_no_context_takeover = value
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def set_bfinal(self, value):
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self._framer.set_bfinal(value)
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def enable_outgoing_compression(self):
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self._framer.set_compress_outgoing_enabled(True)
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def disable_outgoing_compression(self):
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self._framer.set_compress_outgoing_enabled(False)
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class _PerMessageDeflateFramer(object):
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"""A framer for extensions with per-message DEFLATE feature."""
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def __init__(self, deflate_max_window_bits, deflate_no_context_takeover):
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self._logger = util.get_class_logger(self)
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self._rfc1979_deflater = util._RFC1979Deflater(
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deflate_max_window_bits, deflate_no_context_takeover)
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self._rfc1979_inflater = util._RFC1979Inflater()
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self._bfinal = False
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self._compress_outgoing_enabled = False
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# True if a message is fragmented and compression is ongoing.
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self._compress_ongoing = False
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# Calculates
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# (Total outgoing bytes supplied to this filter) /
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# (Total bytes sent to the network after applying this filter)
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self._outgoing_average_ratio_calculator = _AverageRatioCalculator()
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# Calculates
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# (Total bytes received from the network) /
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# (Total incoming bytes obtained after applying this filter)
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self._incoming_average_ratio_calculator = _AverageRatioCalculator()
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def set_bfinal(self, value):
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self._bfinal = value
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def set_compress_outgoing_enabled(self, value):
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self._compress_outgoing_enabled = value
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def _process_incoming_message(self, message, decompress):
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if not decompress:
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return message
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received_payload_size = len(message)
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self._incoming_average_ratio_calculator.add_result_bytes(
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received_payload_size)
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message = self._rfc1979_inflater.filter(message)
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filtered_payload_size = len(message)
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self._incoming_average_ratio_calculator.add_original_bytes(
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filtered_payload_size)
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_log_incoming_compression_ratio(
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self._logger, received_payload_size, filtered_payload_size,
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self._incoming_average_ratio_calculator.get_average_ratio())
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return message
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def _process_outgoing_message(self, message, end, binary):
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if not binary:
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message = message.encode('utf-8')
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if not self._compress_outgoing_enabled:
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return message
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original_payload_size = len(message)
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self._outgoing_average_ratio_calculator.add_original_bytes(
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original_payload_size)
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message = self._rfc1979_deflater.filter(message,
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end=end,
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bfinal=self._bfinal)
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filtered_payload_size = len(message)
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self._outgoing_average_ratio_calculator.add_result_bytes(
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filtered_payload_size)
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_log_outgoing_compression_ratio(
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self._logger, original_payload_size, filtered_payload_size,
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self._outgoing_average_ratio_calculator.get_average_ratio())
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if not self._compress_ongoing:
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self._outgoing_frame_filter.set_compression_bit()
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self._compress_ongoing = not end
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return message
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def _process_incoming_frame(self, frame):
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if frame.rsv1 == 1 and not common.is_control_opcode(frame.opcode):
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self._incoming_message_filter.decompress_next_message()
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frame.rsv1 = 0
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def _process_outgoing_frame(self, frame, compression_bit):
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if (not compression_bit or common.is_control_opcode(frame.opcode)):
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return
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frame.rsv1 = 1
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def setup_stream_options(self, stream_options):
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"""Creates filters and sets them to the StreamOptions."""
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class _OutgoingMessageFilter(object):
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def __init__(self, parent):
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self._parent = parent
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def filter(self, message, end=True, binary=False):
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return self._parent._process_outgoing_message(
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message, end, binary)
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class _IncomingMessageFilter(object):
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def __init__(self, parent):
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self._parent = parent
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self._decompress_next_message = False
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def decompress_next_message(self):
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self._decompress_next_message = True
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def filter(self, message):
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message = self._parent._process_incoming_message(
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message, self._decompress_next_message)
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self._decompress_next_message = False
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return message
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self._outgoing_message_filter = _OutgoingMessageFilter(self)
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self._incoming_message_filter = _IncomingMessageFilter(self)
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stream_options.outgoing_message_filters.append(
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self._outgoing_message_filter)
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stream_options.incoming_message_filters.append(
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self._incoming_message_filter)
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class _OutgoingFrameFilter(object):
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def __init__(self, parent):
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self._parent = parent
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self._set_compression_bit = False
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def set_compression_bit(self):
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self._set_compression_bit = True
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def filter(self, frame):
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self._parent._process_outgoing_frame(frame,
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self._set_compression_bit)
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self._set_compression_bit = False
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class _IncomingFrameFilter(object):
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def __init__(self, parent):
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self._parent = parent
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def filter(self, frame):
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self._parent._process_incoming_frame(frame)
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self._outgoing_frame_filter = _OutgoingFrameFilter(self)
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self._incoming_frame_filter = _IncomingFrameFilter(self)
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stream_options.outgoing_frame_filters.append(
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self._outgoing_frame_filter)
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stream_options.incoming_frame_filters.append(
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self._incoming_frame_filter)
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stream_options.encode_text_message_to_utf8 = False
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_available_processors[common.PERMESSAGE_DEFLATE_EXTENSION] = (
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PerMessageDeflateExtensionProcessor)
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def get_extension_processor(extension_request):
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"""Given an ExtensionParameter representing an extension offer received
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from a client, configures and returns an instance of the corresponding
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extension processor class.
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"""
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processor_class = _available_processors.get(extension_request.name())
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if processor_class is None:
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return None
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return processor_class(extension_request)
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# vi:sts=4 sw=4 et
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