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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.
from mod_pywebsocket import common
from mod_pywebsocket import util
_available_processors = {}
class ExtensionProcessorInterface(object):
def get_extension_response(self):
return None
def setup_stream_options(self, stream_options):
pass
class DeflateStreamExtensionProcessor(ExtensionProcessorInterface):
"""WebSocket DEFLATE stream extension processor."""
def __init__(self, request):
self._logger = util.get_class_logger(self)
self._request = request
def get_extension_response(self):
if len(self._request.get_parameter_names()) != 0:
return None
self._logger.debug(
'Enable %s extension', common.DEFLATE_STREAM_EXTENSION)
return common.ExtensionParameter(common.DEFLATE_STREAM_EXTENSION)
def setup_stream_options(self, stream_options):
stream_options.deflate_stream = True
_available_processors[common.DEFLATE_STREAM_EXTENSION] = (
DeflateStreamExtensionProcessor)
class DeflateFrameExtensionProcessor(ExtensionProcessorInterface):
"""WebSocket Per-frame DEFLATE extension processor."""
_WINDOW_BITS_PARAM = 'max_window_bits'
_NO_CONTEXT_TAKEOVER_PARAM = 'no_context_takeover'
def __init__(self, request):
self._logger = util.get_class_logger(self)
self._request = request
self._response_window_bits = None
self._response_no_context_takeover = False
# Counters for statistics.
# Total number of outgoing bytes supplied to this filter.
self._total_outgoing_payload_bytes = 0
# Total number of bytes sent to the network after applying this filter.
self._total_filtered_outgoing_payload_bytes = 0
# Total number of bytes received from the network.
self._total_incoming_payload_bytes = 0
# Total number of incoming bytes obtained after applying this filter.
self._total_filtered_incoming_payload_bytes = 0
def get_extension_response(self):
# Any unknown parameter will be just ignored.
window_bits = self._request.get_parameter_value(
self._WINDOW_BITS_PARAM)
no_context_takeover = self._request.has_parameter(
self._NO_CONTEXT_TAKEOVER_PARAM)
if (no_context_takeover and
self._request.get_parameter_value(
self._NO_CONTEXT_TAKEOVER_PARAM) is not None):
return None
if window_bits is not None:
try:
window_bits = int(window_bits)
except ValueError, e:
return None
if window_bits < 8 or window_bits > 15:
return None
self._deflater = util._RFC1979Deflater(
window_bits, no_context_takeover)
self._inflater = util._RFC1979Inflater()
self._compress_outgoing = True
response = common.ExtensionParameter(self._request.name())
if self._response_window_bits is not None:
response.add_parameter(
self._WINDOW_BITS_PARAM, str(self._response_window_bits))
if self._response_no_context_takeover:
response.add_parameter(
self._NO_CONTEXT_TAKEOVER_PARAM, None)
self._logger.debug(
'Enable %s extension ('
'request: window_bits=%s; no_context_takeover=%r, '
'response: window_wbits=%s; no_context_takeover=%r)' %
(self._request.name(),
window_bits,
no_context_takeover,
self._response_window_bits,
self._response_no_context_takeover))
return response
def setup_stream_options(self, stream_options):
class _OutgoingFilter(object):
def __init__(self, parent):
self._parent = parent
def filter(self, frame):
self._parent._outgoing_filter(frame)
class _IncomingFilter(object):
def __init__(self, parent):
self._parent = parent
def filter(self, frame):
self._parent._incoming_filter(frame)
stream_options.outgoing_frame_filters.append(
_OutgoingFilter(self))
stream_options.incoming_frame_filters.insert(
0, _IncomingFilter(self))
def set_response_window_bits(self, value):
self._response_window_bits = value
def set_response_no_context_takeover(self, value):
self._response_no_context_takeover = value
def enable_outgoing_compression(self):
self._compress_outgoing = True
def disable_outgoing_compression(self):
self._compress_outgoing = False
def _outgoing_filter(self, frame):
"""Transform outgoing frames. This method is called only by
an _OutgoingFilter instance.
"""
original_payload_size = len(frame.payload)
self._total_outgoing_payload_bytes += original_payload_size
if (not self._compress_outgoing or
common.is_control_opcode(frame.opcode)):
self._total_filtered_outgoing_payload_bytes += (
original_payload_size)
return
frame.payload = self._deflater.filter(frame.payload)
frame.rsv1 = 1
filtered_payload_size = len(frame.payload)
self._total_filtered_outgoing_payload_bytes += filtered_payload_size
# Print inf when ratio is not available.
ratio = float('inf')
average_ratio = float('inf')
if original_payload_size != 0:
ratio = float(filtered_payload_size) / original_payload_size
if self._total_outgoing_payload_bytes != 0:
average_ratio = (
float(self._total_filtered_outgoing_payload_bytes) /
self._total_outgoing_payload_bytes)
self._logger.debug(
'Outgoing compress ratio: %f (average: %f)' %
(ratio, average_ratio))
def _incoming_filter(self, frame):
"""Transform incoming frames. This method is called only by
an _IncomingFilter instance.
"""
received_payload_size = len(frame.payload)
self._total_incoming_payload_bytes += received_payload_size
if frame.rsv1 != 1 or common.is_control_opcode(frame.opcode):
self._total_filtered_incoming_payload_bytes += (
received_payload_size)
return
frame.payload = self._inflater.filter(frame.payload)
frame.rsv1 = 0
filtered_payload_size = len(frame.payload)
self._total_filtered_incoming_payload_bytes += filtered_payload_size
# Print inf when ratio is not available.
ratio = float('inf')
average_ratio = float('inf')
if received_payload_size != 0:
ratio = float(received_payload_size) / filtered_payload_size
if self._total_filtered_incoming_payload_bytes != 0:
average_ratio = (
float(self._total_incoming_payload_bytes) /
self._total_filtered_incoming_payload_bytes)
self._logger.debug(
'Incoming compress ratio: %f (average: %f)' %
(ratio, average_ratio))
_available_processors[common.DEFLATE_FRAME_EXTENSION] = (
DeflateFrameExtensionProcessor)
# Adding vendor-prefixed deflate-frame extension.
# TODO(bashi): Remove this after WebKit stops using vender prefix.
_available_processors[common.X_WEBKIT_DEFLATE_FRAME_EXTENSION] = (
DeflateFrameExtensionProcessor)
def get_extension_processor(extension_request):
global _available_processors
processor_class = _available_processors.get(extension_request.name())
if processor_class is None:
return None
return processor_class(extension_request)
# vi:sts=4 sw=4 et
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