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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  import static io.netty.handler.codec.http.HttpHeaderValues.SNAPPY;
24  
25  import io.netty.channel.embedded.EmbeddedChannel;
26  import io.netty.handler.codec.compression.Brotli;
27  import io.netty.handler.codec.compression.BrotliDecoder;
28  import io.netty.handler.codec.compression.ZlibCodecFactory;
29  import io.netty.handler.codec.compression.ZlibWrapper;
30  import io.netty.handler.codec.compression.SnappyFrameDecoder;
31  
32  /**
33   * Decompresses an {@link HttpMessage} and an {@link HttpContent} compressed in
34   * {@code gzip} or {@code deflate} encoding.  For more information on how this
35   * handler modifies the message, please refer to {@link HttpContentDecoder}.
36   */
37  public class HttpContentDecompressor extends HttpContentDecoder {
38  
39      private final boolean strict;
40  
41      /**
42       * Create a new {@link HttpContentDecompressor} in non-strict mode.
43       */
44      public HttpContentDecompressor() {
45          this(false);
46      }
47  
48      /**
49       * Create a new {@link HttpContentDecompressor}.
50       *
51       * @param strict    if {@code true} use strict handling of deflate if used, otherwise handle it in a
52       *                  more lenient fashion.
53       */
54      public HttpContentDecompressor(boolean strict) {
55          this.strict = strict;
56      }
57  
58      @Override
59      protected EmbeddedChannel newContentDecoder(String contentEncoding) throws Exception {
60          if (GZIP.contentEqualsIgnoreCase(contentEncoding) ||
61              X_GZIP.contentEqualsIgnoreCase(contentEncoding)) {
62              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
63                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP));
64          }
65          if (DEFLATE.contentEqualsIgnoreCase(contentEncoding) ||
66              X_DEFLATE.contentEqualsIgnoreCase(contentEncoding)) {
67              final ZlibWrapper wrapper = strict ? ZlibWrapper.ZLIB : ZlibWrapper.ZLIB_OR_NONE;
68              // To be strict, 'deflate' means ZLIB, but some servers were not implemented correctly.
69              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
70                      ctx.channel().config(), ZlibCodecFactory.newZlibDecoder(wrapper));
71          }
72          if (Brotli.isAvailable() && BR.contentEqualsIgnoreCase(contentEncoding)) {
73              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
74                ctx.channel().config(), new BrotliDecoder());
75          }
76  
77          if (SNAPPY.contentEqualsIgnoreCase(contentEncoding)) {
78              return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
79                      ctx.channel().config(), new SnappyFrameDecoder());
80          }
81  
82          // 'identity' or unsupported
83          return null;
84      }
85  }