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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 static io.netty.handler.codec.http.HttpHeaderValues.DEFLATE;
19  import static io.netty.handler.codec.http.HttpHeaderValues.GZIP;
20  import static io.netty.handler.codec.http.HttpHeaderValues.X_DEFLATE;
21  import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
22  
23  import io.netty.channel.embedded.EmbeddedChannel;
24  import io.netty.handler.codec.compression.ZlibCodecFactory;
25  import io.netty.handler.codec.compression.ZlibWrapper;
26  
27  /**
28   * Decompresses an {@link HttpMessage} and an {@link HttpContent} compressed in
29   * {@code gzip} or {@code deflate} encoding.  For more information on how this
30   * handler modifies the message, please refer to {@link HttpContentDecoder}.
31   */
32  public class HttpContentDecompressor extends HttpContentDecoder {
33  
34      private final boolean strict;
35  
36      /**
37       * Create a new {@link HttpContentDecompressor} in non-strict mode.
38       */
39      public HttpContentDecompressor() {
40          this(false);
41      }
42  
43      /**
44       * Create a new {@link HttpContentDecompressor}.
45       *
46       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
47       *                  more lenient fashion.
48       */
49      public HttpContentDecompressor(boolean strict) {
50          this.strict = strict;
51      }
52  
53      @Override
54      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
55          if (GZIP.contentEqualsIgnoreCase(contentEncoding) ||
56              X_GZIP.contentEqualsIgnoreCase(contentEncoding)) {
57              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
58                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
59          }
60          if (DEFLATE.contentEqualsIgnoreCase(contentEncoding) ||
61              X_DEFLATE.contentEqualsIgnoreCase(contentEncoding)) {
62              final ZlibWrapper wrapper = strict ? ZlibWrapper.ZLIB : ZlibWrapper.ZLIB_OR_NONE;
63              // To be strict, 'deflate' means ZLIB, but some servers were not implemented correctly.
64              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
65                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(wrapper));
66          }
67  
68          // 'identity' or unsupported
69          return null;
70      }
71  }