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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 decompressor.
27   */
28  class PerFrameDeflateDecoder extends DeflateDecoder {
29  
30      /**
31       * Constructor
32       *
33       * @param noContext true to disable context takeover.
34       */
35      PerFrameDeflateDecoder(boolean noContext) {
36          super(noContext, WebSocketExtensionFilter.NEVER_SKIP);
37      }
38  
39      /**
40       * Constructor
41       *
42       * @param noContext true to disable context takeover.
43       * @param extensionDecoderFilter extension decoder filter for per frame deflate decoder.
44       */
45      PerFrameDeflateDecoder(boolean noContext, WebSocketExtensionFilter extensionDecoderFilter) {
46          super(noContext, extensionDecoderFilter);
47      }
48  
49      @Override
50      public boolean acceptInboundMessage(Object msg) throws Exception {
51          if (!super.acceptInboundMessage(msg)) {
52              return false;
53          }
54  
55          WebSocketFrame wsFrame = (WebSocketFrame) msg;
56          if (extensionDecoderFilter().mustSkip(wsFrame)) {
57              return false;
58          }
59  
60          return (msg instanceof TextWebSocketFrame || msg instanceof BinaryWebSocketFrame ||
61                  msg instanceof ContinuationWebSocketFrame) &&
62                 (wsFrame.rsv() & WebSocketExtension.RSV1) > 0;
63      }
64  
65      @Override
66      protected int newRsv(WebSocketFrame msg) {
67          return msg.rsv() ^ WebSocketExtension.RSV1;
68      }
69  
70      @Override
71      protected boolean appendFrameTail(WebSocketFrame msg) {
72          return true;
73      }
74  
75  }