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1 # Copyright 2011, Google Inc. |
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2 # All rights reserved. |
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3 # |
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4 # Redistribution and use in source and binary forms, with or without |
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5 # modification, are permitted provided that the following conditions are |
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6 # met: |
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7 # |
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8 # * Redistributions of source code must retain the above copyright |
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9 # notice, this list of conditions and the following disclaimer. |
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10 # * Redistributions in binary form must reproduce the above |
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11 # copyright notice, this list of conditions and the following disclaimer |
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12 # in the documentation and/or other materials provided with the |
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13 # distribution. |
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14 # * Neither the name of Google Inc. nor the names of its |
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15 # contributors may be used to endorse or promote products derived from |
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16 # this software without specific prior written permission. |
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17 # |
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18 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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19 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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20 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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21 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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22 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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23 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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24 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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25 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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26 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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27 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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28 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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29 |
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30 |
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31 from mod_pywebsocket import common |
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32 from mod_pywebsocket import util |
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33 |
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34 |
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35 _available_processors = {} |
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36 |
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37 |
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38 class ExtensionProcessorInterface(object): |
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39 |
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40 def get_extension_response(self): |
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41 return None |
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42 |
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43 def setup_stream_options(self, stream_options): |
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44 pass |
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45 |
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46 |
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47 class DeflateStreamExtensionProcessor(ExtensionProcessorInterface): |
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48 """WebSocket DEFLATE stream extension processor.""" |
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49 |
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50 def __init__(self, request): |
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51 self._logger = util.get_class_logger(self) |
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52 |
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53 self._request = request |
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54 |
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55 def get_extension_response(self): |
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56 if len(self._request.get_parameter_names()) != 0: |
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57 return None |
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58 |
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59 self._logger.debug( |
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60 'Enable %s extension', common.DEFLATE_STREAM_EXTENSION) |
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61 |
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62 return common.ExtensionParameter(common.DEFLATE_STREAM_EXTENSION) |
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63 |
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64 def setup_stream_options(self, stream_options): |
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65 stream_options.deflate_stream = True |
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66 |
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67 |
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68 _available_processors[common.DEFLATE_STREAM_EXTENSION] = ( |
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69 DeflateStreamExtensionProcessor) |
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70 |
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71 |
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72 class DeflateFrameExtensionProcessor(ExtensionProcessorInterface): |
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73 """WebSocket Per-frame DEFLATE extension processor.""" |
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74 |
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75 _WINDOW_BITS_PARAM = 'max_window_bits' |
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76 _NO_CONTEXT_TAKEOVER_PARAM = 'no_context_takeover' |
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77 |
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78 def __init__(self, request): |
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79 self._logger = util.get_class_logger(self) |
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80 |
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81 self._request = request |
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82 |
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83 self._response_window_bits = None |
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84 self._response_no_context_takeover = False |
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85 |
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86 # Counters for statistics. |
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87 |
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88 # Total number of outgoing bytes supplied to this filter. |
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89 self._total_outgoing_payload_bytes = 0 |
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90 # Total number of bytes sent to the network after applying this filter. |
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91 self._total_filtered_outgoing_payload_bytes = 0 |
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92 |
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93 # Total number of bytes received from the network. |
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94 self._total_incoming_payload_bytes = 0 |
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95 # Total number of incoming bytes obtained after applying this filter. |
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96 self._total_filtered_incoming_payload_bytes = 0 |
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97 |
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98 def get_extension_response(self): |
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99 # Any unknown parameter will be just ignored. |
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100 |
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101 window_bits = self._request.get_parameter_value( |
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102 self._WINDOW_BITS_PARAM) |
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103 no_context_takeover = self._request.has_parameter( |
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104 self._NO_CONTEXT_TAKEOVER_PARAM) |
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105 if (no_context_takeover and |
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106 self._request.get_parameter_value( |
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107 self._NO_CONTEXT_TAKEOVER_PARAM) is not None): |
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108 return None |
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109 |
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110 if window_bits is not None: |
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111 try: |
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112 window_bits = int(window_bits) |
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113 except ValueError, e: |
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114 return None |
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115 if window_bits < 8 or window_bits > 15: |
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116 return None |
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117 |
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118 self._deflater = util._RFC1979Deflater( |
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119 window_bits, no_context_takeover) |
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120 |
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121 self._inflater = util._RFC1979Inflater() |
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122 |
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123 self._compress_outgoing = True |
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124 |
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125 response = common.ExtensionParameter(self._request.name()) |
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126 |
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127 if self._response_window_bits is not None: |
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128 response.add_parameter( |
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129 self._WINDOW_BITS_PARAM, str(self._response_window_bits)) |
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130 if self._response_no_context_takeover: |
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131 response.add_parameter( |
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132 self._NO_CONTEXT_TAKEOVER_PARAM, None) |
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133 |
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134 self._logger.debug( |
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135 'Enable %s extension (' |
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136 'request: window_bits=%s; no_context_takeover=%r, ' |
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137 'response: window_wbits=%s; no_context_takeover=%r)' % |
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138 (self._request.name(), |
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139 window_bits, |
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140 no_context_takeover, |
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141 self._response_window_bits, |
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142 self._response_no_context_takeover)) |
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143 |
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144 return response |
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145 |
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146 def setup_stream_options(self, stream_options): |
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147 |
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148 class _OutgoingFilter(object): |
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149 |
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150 def __init__(self, parent): |
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151 self._parent = parent |
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152 |
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153 def filter(self, frame): |
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154 self._parent._outgoing_filter(frame) |
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155 |
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156 class _IncomingFilter(object): |
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157 |
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158 def __init__(self, parent): |
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159 self._parent = parent |
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160 |
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161 def filter(self, frame): |
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162 self._parent._incoming_filter(frame) |
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163 |
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164 stream_options.outgoing_frame_filters.append( |
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165 _OutgoingFilter(self)) |
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166 stream_options.incoming_frame_filters.insert( |
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167 0, _IncomingFilter(self)) |
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168 |
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169 def set_response_window_bits(self, value): |
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170 self._response_window_bits = value |
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171 |
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172 def set_response_no_context_takeover(self, value): |
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173 self._response_no_context_takeover = value |
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174 |
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175 def enable_outgoing_compression(self): |
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176 self._compress_outgoing = True |
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177 |
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178 def disable_outgoing_compression(self): |
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179 self._compress_outgoing = False |
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180 |
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181 def _outgoing_filter(self, frame): |
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182 """Transform outgoing frames. This method is called only by |
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183 an _OutgoingFilter instance. |
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184 """ |
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185 |
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186 original_payload_size = len(frame.payload) |
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187 self._total_outgoing_payload_bytes += original_payload_size |
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188 |
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189 if (not self._compress_outgoing or |
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190 common.is_control_opcode(frame.opcode)): |
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191 self._total_filtered_outgoing_payload_bytes += ( |
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192 original_payload_size) |
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193 return |
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194 |
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195 frame.payload = self._deflater.filter(frame.payload) |
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196 frame.rsv1 = 1 |
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197 |
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198 filtered_payload_size = len(frame.payload) |
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199 self._total_filtered_outgoing_payload_bytes += filtered_payload_size |
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200 |
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201 # Print inf when ratio is not available. |
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202 ratio = float('inf') |
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203 average_ratio = float('inf') |
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204 if original_payload_size != 0: |
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205 ratio = float(filtered_payload_size) / original_payload_size |
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206 if self._total_outgoing_payload_bytes != 0: |
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207 average_ratio = ( |
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208 float(self._total_filtered_outgoing_payload_bytes) / |
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209 self._total_outgoing_payload_bytes) |
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210 self._logger.debug( |
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211 'Outgoing compress ratio: %f (average: %f)' % |
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212 (ratio, average_ratio)) |
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213 |
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214 def _incoming_filter(self, frame): |
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215 """Transform incoming frames. This method is called only by |
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216 an _IncomingFilter instance. |
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217 """ |
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218 |
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219 received_payload_size = len(frame.payload) |
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220 self._total_incoming_payload_bytes += received_payload_size |
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221 |
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222 if frame.rsv1 != 1 or common.is_control_opcode(frame.opcode): |
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223 self._total_filtered_incoming_payload_bytes += ( |
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224 received_payload_size) |
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225 return |
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226 |
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227 frame.payload = self._inflater.filter(frame.payload) |
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228 frame.rsv1 = 0 |
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229 |
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230 filtered_payload_size = len(frame.payload) |
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231 self._total_filtered_incoming_payload_bytes += filtered_payload_size |
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232 |
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233 # Print inf when ratio is not available. |
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234 ratio = float('inf') |
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235 average_ratio = float('inf') |
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236 if received_payload_size != 0: |
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237 ratio = float(received_payload_size) / filtered_payload_size |
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238 if self._total_filtered_incoming_payload_bytes != 0: |
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239 average_ratio = ( |
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240 float(self._total_incoming_payload_bytes) / |
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241 self._total_filtered_incoming_payload_bytes) |
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242 self._logger.debug( |
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243 'Incoming compress ratio: %f (average: %f)' % |
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244 (ratio, average_ratio)) |
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245 |
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246 |
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247 _available_processors[common.DEFLATE_FRAME_EXTENSION] = ( |
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248 DeflateFrameExtensionProcessor) |
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249 |
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250 |
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251 # Adding vendor-prefixed deflate-frame extension. |
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252 # TODO(bashi): Remove this after WebKit stops using vender prefix. |
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253 _available_processors[common.X_WEBKIT_DEFLATE_FRAME_EXTENSION] = ( |
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254 DeflateFrameExtensionProcessor) |
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255 |
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256 |
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257 def get_extension_processor(extension_request): |
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258 global _available_processors |
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259 processor_class = _available_processors.get(extension_request.name()) |
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260 if processor_class is None: |
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261 return None |
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262 return processor_class(extension_request) |
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263 |
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264 |
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265 # vi:sts=4 sw=4 et |