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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    *   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;
17  
18  import static io.netty.handler.codec.http.HttpHeaderValues.BR;
19  import static io.netty.handler.codec.http.HttpHeaderValues.DEFLATE;
20  import static io.netty.handler.codec.http.HttpHeaderValues.GZIP;
21  import static io.netty.handler.codec.http.HttpHeaderValues.X_DEFLATE;
22  import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
23  
24  import io.netty.channel.embedded.EmbeddedChannel;
25  import io.netty.handler.codec.compression.Brotli;
26  import io.netty.handler.codec.compression.BrotliDecoder;
27  import io.netty.handler.codec.compression.ZlibCodecFactory;
28  import io.netty.handler.codec.compression.ZlibWrapper;
29  
30  /**
31   * Decompresses an {@link HttpMessage} and an {@link HttpContent} compressed in
32   * {@code gzip} or {@code deflate} encoding.  For more information on how this
33   * handler modifies the message, please refer to {@link HttpContentDecoder}.
34   */
35  public class HttpContentDecompressor extends HttpContentDecoder {
36  
37      private final boolean strict;
38  
39      /**
40       * Create a new {@link HttpContentDecompressor} in non-strict mode.
41       */
42      public HttpContentDecompressor() {
43          this(false);
44      }
45  
46      /**
47       * Create a new {@link HttpContentDecompressor}.
48       *
49       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
50       *                  more lenient fashion.
51       */
52      public HttpContentDecompressor(boolean strict) {
53          this.strict = strict;
54      }
55  
56      @Override
57      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
58          if (GZIP.contentEqualsIgnoreCase(contentEncoding) ||
59              X_GZIP.contentEqualsIgnoreCase(contentEncoding)) {
60              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
61                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
62          }
63          if (DEFLATE.contentEqualsIgnoreCase(contentEncoding) ||
64              X_DEFLATE.contentEqualsIgnoreCase(contentEncoding)) {
65              final ZlibWrapper wrapper = strict ? ZlibWrapper.ZLIB : ZlibWrapper.ZLIB_OR_NONE;
66              // To be strict, 'deflate' means ZLIB, but some servers were not implemented correctly.
67              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
68                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(wrapper));
69          }
70          if (Brotli.isAvailable() && BR.contentEqualsIgnoreCase(contentEncoding)) {
71              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
72                ctx.channel().config(), new BrotliDecoder());
73          }
74  
75          // 'identity' or unsupported
76          return null;
77      }
78  }