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1   /*
2    * Copyright 2014 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.http.websocketx.extensions.compression;
17  
18  import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame;
19  import io.netty.handler.codec.http.websocketx.ContinuationWebSocketFrame;
20  import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
21  import io.netty.handler.codec.http.websocketx.WebSocketFrame;
22  import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtension;
23  import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionFilter;
24  
25  /**
26   * Per-frame implementation of deflate compressor.
27   */
28  class PerFrameDeflateEncoder extends DeflateEncoder {
29  
30      /**
31       * Constructor
32       *
33       * @param compressionLevel compression level of the compressor.
34       * @param windowSize       maximum size of the window compressor buffer.
35       * @param noContext        true to disable context takeover.
36       */
37      PerFrameDeflateEncoder(int compressionLevel, int windowSize, boolean noContext) {
38          super(compressionLevel, windowSize, noContext, WebSocketExtensionFilter.NEVER_SKIP);
39      }
40  
41      /**
42       * Constructor
43       *
44       * @param compressionLevel compression level of the compressor.
45       * @param windowSize       maximum size of the window compressor buffer.
46       * @param noContext        true to disable context takeover.
47       * @param extensionEncoderFilter extension encoder filter for per frame deflate encoder.
48       */
49      PerFrameDeflateEncoder(int compressionLevel, int windowSize, boolean noContext,
50                             WebSocketExtensionFilter extensionEncoderFilter) {
51          super(compressionLevel, windowSize, noContext, extensionEncoderFilter);
52      }
53  
54      @Override
55      public boolean acceptOutboundMessage(Object msg) throws Exception {
56          if (!super.acceptOutboundMessage(msg)) {
57              return false;
58          }
59  
60          WebSocketFrame wsFrame = (WebSocketFrame) msg;
61          if (extensionEncoderFilter().mustSkip(wsFrame)) {
62              return false;
63          }
64  
65          return (msg instanceof TextWebSocketFrame || msg instanceof BinaryWebSocketFrame ||
66                  msg instanceof ContinuationWebSocketFrame) &&
67                 wsFrame.content().readableBytes() > 0 &&
68                 (wsFrame.rsv() & WebSocketExtension.RSV1) == 0;
69      }
70  
71      @Override
72      protected int rsv(WebSocketFrame msg) {
73          return msg.rsv() | WebSocketExtension.RSV1;
74      }
75  
76      @Override
77      protected boolean removeFrameTail(WebSocketFrame msg) {
78          return true;
79      }
80  
81  }