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1   /*
2    * Copyright 2012 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    *   http://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;
17  
18  import io.netty.channel.embedded.EmbeddedChannel;
19  import io.netty.handler.codec.compression.ZlibCodecFactory;
20  import io.netty.handler.codec.compression.ZlibWrapper;
21  
22  /**
23   * Decompresses an {@link HttpMessage} and an {@link HttpContent} compressed in
24   * {@code gzip} or {@code deflate} encoding.  For more information on how this
25   * handler modifies the message, please refer to {@link HttpContentDecoder}.
26   */
27  public class HttpContentDecompressor extends HttpContentDecoder {
28  
29      private final boolean strict;
30  
31      /**
32       * Create a new {@link HttpContentDecompressor} in non-strict mode.
33       */
34      public HttpContentDecompressor() {
35          this(false);
36      }
37  
38      /**
39       * Create a new {@link HttpContentDecompressor}.
40       *
41       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
42       *                  more lenient fashion.
43       */
44      public HttpContentDecompressor(boolean strict) {
45          this.strict = strict;
46      }
47  
48      @Override
49      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
50          if ("gzip".equalsIgnoreCase(contentEncoding) || "x-gzip".equalsIgnoreCase(contentEncoding)) {
51              return new EmbeddedChannel(ctx.channel().metadata().hasDisconnect(),
52                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
53          }
54          if ("deflate".equalsIgnoreCase(contentEncoding) || "x-deflate".equalsIgnoreCase(contentEncoding)) {
55              ZlibWrapper wrapper;
56              if (strict) {
57                  wrapper = ZlibWrapper.ZLIB;
58              }   else {
59                  wrapper = ZlibWrapper.ZLIB_OR_NONE;
60              }
61              // To be strict, 'deflate' means ZLIB, but some servers were not implemented correctly.
62              return new EmbeddedChannel(ctx.channel().metadata().hasDisconnect(),
63                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(wrapper));
64          }
65  
66          // 'identity' or unsupported
67          return null;
68      }
69  }