michael@0: # Copyright 2011, Google Inc.
michael@0: # All rights reserved.
michael@0: #
michael@0: # Redistribution and use in source and binary forms, with or without
michael@0: # modification, are permitted provided that the following conditions are
michael@0: # met:
michael@0: #
michael@0: #     * Redistributions of source code must retain the above copyright
michael@0: # notice, this list of conditions and the following disclaimer.
michael@0: #     * Redistributions in binary form must reproduce the above
michael@0: # copyright notice, this list of conditions and the following disclaimer
michael@0: # in the documentation and/or other materials provided with the
michael@0: # distribution.
michael@0: #     * Neither the name of Google Inc. nor the names of its
michael@0: # contributors may be used to endorse or promote products derived from
michael@0: # this software without specific prior written permission.
michael@0: #
michael@0: # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: 
michael@0: from mod_pywebsocket import common
michael@0: from mod_pywebsocket import util
michael@0: 
michael@0: 
michael@0: _available_processors = {}
michael@0: 
michael@0: 
michael@0: class ExtensionProcessorInterface(object):
michael@0: 
michael@0:     def get_extension_response(self):
michael@0:         return None
michael@0: 
michael@0:     def setup_stream_options(self, stream_options):
michael@0:         pass
michael@0: 
michael@0: 
michael@0: class DeflateStreamExtensionProcessor(ExtensionProcessorInterface):
michael@0:     """WebSocket DEFLATE stream extension processor."""
michael@0: 
michael@0:     def __init__(self, request):
michael@0:         self._logger = util.get_class_logger(self)
michael@0: 
michael@0:         self._request = request
michael@0: 
michael@0:     def get_extension_response(self):
michael@0:         if len(self._request.get_parameter_names()) != 0:
michael@0:             return None
michael@0: 
michael@0:         self._logger.debug(
michael@0:             'Enable %s extension', common.DEFLATE_STREAM_EXTENSION)
michael@0: 
michael@0:         return common.ExtensionParameter(common.DEFLATE_STREAM_EXTENSION)
michael@0: 
michael@0:     def setup_stream_options(self, stream_options):
michael@0:         stream_options.deflate_stream = True
michael@0: 
michael@0: 
michael@0: _available_processors[common.DEFLATE_STREAM_EXTENSION] = (
michael@0:     DeflateStreamExtensionProcessor)
michael@0: 
michael@0: 
michael@0: class DeflateFrameExtensionProcessor(ExtensionProcessorInterface):
michael@0:     """WebSocket Per-frame DEFLATE extension processor."""
michael@0: 
michael@0:     _WINDOW_BITS_PARAM = 'max_window_bits'
michael@0:     _NO_CONTEXT_TAKEOVER_PARAM = 'no_context_takeover'
michael@0: 
michael@0:     def __init__(self, request):
michael@0:         self._logger = util.get_class_logger(self)
michael@0: 
michael@0:         self._request = request
michael@0: 
michael@0:         self._response_window_bits = None
michael@0:         self._response_no_context_takeover = False
michael@0: 
michael@0:         # Counters for statistics.
michael@0: 
michael@0:         # Total number of outgoing bytes supplied to this filter.
michael@0:         self._total_outgoing_payload_bytes = 0
michael@0:         # Total number of bytes sent to the network after applying this filter.
michael@0:         self._total_filtered_outgoing_payload_bytes = 0
michael@0: 
michael@0:         # Total number of bytes received from the network.
michael@0:         self._total_incoming_payload_bytes = 0
michael@0:         # Total number of incoming bytes obtained after applying this filter.
michael@0:         self._total_filtered_incoming_payload_bytes = 0
michael@0: 
michael@0:     def get_extension_response(self):
michael@0:         # Any unknown parameter will be just ignored.
michael@0: 
michael@0:         window_bits = self._request.get_parameter_value(
michael@0:             self._WINDOW_BITS_PARAM)
michael@0:         no_context_takeover = self._request.has_parameter(
michael@0:             self._NO_CONTEXT_TAKEOVER_PARAM)
michael@0:         if (no_context_takeover and
michael@0:             self._request.get_parameter_value(
michael@0:                 self._NO_CONTEXT_TAKEOVER_PARAM) is not None):
michael@0:             return None
michael@0: 
michael@0:         if window_bits is not None:
michael@0:             try:
michael@0:                 window_bits = int(window_bits)
michael@0:             except ValueError, e:
michael@0:                 return None
michael@0:             if window_bits < 8 or window_bits > 15:
michael@0:                 return None
michael@0: 
michael@0:         self._deflater = util._RFC1979Deflater(
michael@0:             window_bits, no_context_takeover)
michael@0: 
michael@0:         self._inflater = util._RFC1979Inflater()
michael@0: 
michael@0:         self._compress_outgoing = True
michael@0: 
michael@0:         response = common.ExtensionParameter(self._request.name())
michael@0: 
michael@0:         if self._response_window_bits is not None:
michael@0:             response.add_parameter(
michael@0:                 self._WINDOW_BITS_PARAM, str(self._response_window_bits))
michael@0:         if self._response_no_context_takeover:
michael@0:             response.add_parameter(
michael@0:                 self._NO_CONTEXT_TAKEOVER_PARAM, None)
michael@0: 
michael@0:         self._logger.debug(
michael@0:             'Enable %s extension ('
michael@0:             'request: window_bits=%s; no_context_takeover=%r, '
michael@0:             'response: window_wbits=%s; no_context_takeover=%r)' %
michael@0:             (self._request.name(),
michael@0:              window_bits,
michael@0:              no_context_takeover,
michael@0:              self._response_window_bits,
michael@0:              self._response_no_context_takeover))
michael@0: 
michael@0:         return response
michael@0: 
michael@0:     def setup_stream_options(self, stream_options):
michael@0: 
michael@0:         class _OutgoingFilter(object):
michael@0: 
michael@0:             def __init__(self, parent):
michael@0:                 self._parent = parent
michael@0: 
michael@0:             def filter(self, frame):
michael@0:                 self._parent._outgoing_filter(frame)
michael@0: 
michael@0:         class _IncomingFilter(object):
michael@0: 
michael@0:             def __init__(self, parent):
michael@0:                 self._parent = parent
michael@0: 
michael@0:             def filter(self, frame):
michael@0:                 self._parent._incoming_filter(frame)
michael@0: 
michael@0:         stream_options.outgoing_frame_filters.append(
michael@0:             _OutgoingFilter(self))
michael@0:         stream_options.incoming_frame_filters.insert(
michael@0:             0, _IncomingFilter(self))
michael@0: 
michael@0:     def set_response_window_bits(self, value):
michael@0:         self._response_window_bits = value
michael@0: 
michael@0:     def set_response_no_context_takeover(self, value):
michael@0:         self._response_no_context_takeover = value
michael@0: 
michael@0:     def enable_outgoing_compression(self):
michael@0:         self._compress_outgoing = True
michael@0: 
michael@0:     def disable_outgoing_compression(self):
michael@0:         self._compress_outgoing = False
michael@0: 
michael@0:     def _outgoing_filter(self, frame):
michael@0:         """Transform outgoing frames. This method is called only by
michael@0:         an _OutgoingFilter instance.
michael@0:         """
michael@0: 
michael@0:         original_payload_size = len(frame.payload)
michael@0:         self._total_outgoing_payload_bytes += original_payload_size
michael@0: 
michael@0:         if (not self._compress_outgoing or
michael@0:             common.is_control_opcode(frame.opcode)):
michael@0:             self._total_filtered_outgoing_payload_bytes += (
michael@0:                 original_payload_size)
michael@0:             return
michael@0: 
michael@0:         frame.payload = self._deflater.filter(frame.payload)
michael@0:         frame.rsv1 = 1
michael@0: 
michael@0:         filtered_payload_size = len(frame.payload)
michael@0:         self._total_filtered_outgoing_payload_bytes += filtered_payload_size
michael@0: 
michael@0:         # Print inf when ratio is not available.
michael@0:         ratio = float('inf')
michael@0:         average_ratio = float('inf')
michael@0:         if original_payload_size != 0:
michael@0:             ratio = float(filtered_payload_size) / original_payload_size
michael@0:         if self._total_outgoing_payload_bytes != 0:
michael@0:             average_ratio = (
michael@0:                 float(self._total_filtered_outgoing_payload_bytes) /
michael@0:                 self._total_outgoing_payload_bytes)
michael@0:         self._logger.debug(
michael@0:             'Outgoing compress ratio: %f (average: %f)' %
michael@0:             (ratio, average_ratio))
michael@0: 
michael@0:     def _incoming_filter(self, frame):
michael@0:         """Transform incoming frames. This method is called only by
michael@0:         an _IncomingFilter instance.
michael@0:         """
michael@0: 
michael@0:         received_payload_size = len(frame.payload)
michael@0:         self._total_incoming_payload_bytes += received_payload_size
michael@0: 
michael@0:         if frame.rsv1 != 1 or common.is_control_opcode(frame.opcode):
michael@0:             self._total_filtered_incoming_payload_bytes += (
michael@0:                 received_payload_size)
michael@0:             return
michael@0: 
michael@0:         frame.payload = self._inflater.filter(frame.payload)
michael@0:         frame.rsv1 = 0
michael@0: 
michael@0:         filtered_payload_size = len(frame.payload)
michael@0:         self._total_filtered_incoming_payload_bytes += filtered_payload_size
michael@0: 
michael@0:         # Print inf when ratio is not available.
michael@0:         ratio = float('inf')
michael@0:         average_ratio = float('inf')
michael@0:         if received_payload_size != 0:
michael@0:             ratio = float(received_payload_size) / filtered_payload_size
michael@0:         if self._total_filtered_incoming_payload_bytes != 0:
michael@0:             average_ratio = (
michael@0:                 float(self._total_incoming_payload_bytes) /
michael@0:                 self._total_filtered_incoming_payload_bytes)
michael@0:         self._logger.debug(
michael@0:             'Incoming compress ratio: %f (average: %f)' %
michael@0:             (ratio, average_ratio))
michael@0: 
michael@0: 
michael@0: _available_processors[common.DEFLATE_FRAME_EXTENSION] = (
michael@0:     DeflateFrameExtensionProcessor)
michael@0: 
michael@0: 
michael@0: # Adding vendor-prefixed deflate-frame extension.
michael@0: # TODO(bashi): Remove this after WebKit stops using vender prefix.
michael@0: _available_processors[common.X_WEBKIT_DEFLATE_FRAME_EXTENSION] = (
michael@0:     DeflateFrameExtensionProcessor)
michael@0: 
michael@0: 
michael@0: def get_extension_processor(extension_request):
michael@0:     global _available_processors
michael@0:     processor_class = _available_processors.get(extension_request.name())
michael@0:     if processor_class is None:
michael@0:         return None
michael@0:     return processor_class(extension_request)
michael@0: 
michael@0: 
michael@0: # vi:sts=4 sw=4 et