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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.buffer.ByteBuf;
19  import io.netty.buffer.Unpooled;
20  import io.netty.channel.ChannelPipeline;
21  import io.netty.handler.codec.TooLongFrameException;
22  
23  
24  /**
25   * Decodes {@link ByteBuf}s into {@link HttpResponse}s and
26   * {@link HttpContent}s.
27   *
28   * <h3>Parameters that prevents excessive memory consumption</h3>
29   * <table border="1">
30   * <tr>
31   * <th>Name</th><th>Meaning</th>
32   * </tr>
33   * <tr>
34   * <td>{@code maxInitialLineLength}</td>
35   * <td>The maximum length of the initial line (e.g. {@code "HTTP/1.0 200 OK"})
36   *     If the length of the initial line exceeds this value, a
37   *     {@link TooLongFrameException} will be raised.</td>
38   * </tr>
39   * <tr>
40   * <td>{@code maxHeaderSize}</td>
41   * <td>The maximum length of all headers.  If the sum of the length of each
42   *     header exceeds this value, a {@link TooLongFrameException} will be raised.</td>
43   * </tr>
44   * <tr>
45   * <td>{@code maxChunkSize}</td>
46   * <td>The maximum length of the content or each chunk.  If the content length
47   *     exceeds this value, the transfer encoding of the decoded response will be
48   *     converted to 'chunked' and the content will be split into multiple
49   *     {@link HttpContent}s.  If the transfer encoding of the HTTP response is
50   *     'chunked' already, each chunk will be split into smaller chunks if the
51   *     length of the chunk exceeds this value.  If you prefer not to handle
52   *     {@link HttpContent}s in your handler, insert {@link HttpObjectAggregator}
53   *     after this decoder in the {@link ChannelPipeline}.</td>
54   * </tr>
55   * </table>
56   *
57   * <h3>Decoding a response for a <tt>HEAD</tt> request</h3>
58   * <p>
59   * Unlike other HTTP requests, the successful response of a <tt>HEAD</tt>
60   * request does not have any content even if there is <tt>Content-Length</tt>
61   * header.  Because {@link HttpResponseDecoder} is not able to determine if the
62   * response currently being decoded is associated with a <tt>HEAD</tt> request,
63   * you must override {@link #isContentAlwaysEmpty(HttpMessage)} to return
64   * <tt>true</tt> for the response of the <tt>HEAD</tt> request.
65   * </p><p>
66   * If you are writing an HTTP client that issues a <tt>HEAD</tt> request,
67   * please use {@link HttpClientCodec} instead of this decoder.  It will perform
68   * additional state management to handle the responses for <tt>HEAD</tt>
69   * requests correctly.
70   * </p>
71   *
72   * <h3>Decoding a response for a <tt>CONNECT</tt> request</h3>
73   * <p>
74   * You also need to do additional state management to handle the response of a
75   * <tt>CONNECT</tt> request properly, like you did for <tt>HEAD</tt>.  One
76   * difference is that the decoder should stop decoding completely after decoding
77   * the successful 200 response since the connection is not an HTTP connection
78   * anymore.
79   * </p><p>
80   * {@link HttpClientCodec} also handles this edge case correctly, so you have to
81   * use {@link HttpClientCodec} if you are writing an HTTP client that issues a
82   * <tt>CONNECT</tt> request.
83   * </p>
84   */
85  public class HttpResponseDecoder extends HttpObjectDecoder {
86  
87      private static final HttpResponseStatus UNKNOWN_STATUS = new HttpResponseStatus(999, "Unknown");
88  
89      /**
90       * Creates a new instance with the default
91       * {@code maxInitialLineLength (4096)}, {@code maxHeaderSize (8192)}, and
92       * {@code maxChunkSize (8192)}.
93       */
94      public HttpResponseDecoder() {
95      }
96  
97      /**
98       * Creates a new instance with the specified parameters.
99       */
100     public HttpResponseDecoder(
101             int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) {
102         super(maxInitialLineLength, maxHeaderSize, maxChunkSize, true);
103     }
104 
105     public HttpResponseDecoder(
106             int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders) {
107         super(maxInitialLineLength, maxHeaderSize, maxChunkSize, true, validateHeaders);
108     }
109 
110     public HttpResponseDecoder(
111             int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders,
112             int initialBufferSize) {
113         super(maxInitialLineLength, maxHeaderSize, maxChunkSize, true, validateHeaders, initialBufferSize);
114     }
115 
116     @Override
117     protected HttpMessage createMessage(String[] initialLine) {
118         return new DefaultHttpResponse(
119                 HttpVersion.valueOf(initialLine[0]),
120                 new HttpResponseStatus(Integer.parseInt(initialLine[1]), initialLine[2]), validateHeaders);
121     }
122 
123     @Override
124     protected HttpMessage createInvalidMessage() {
125         return new DefaultFullHttpResponse(
126                 HttpVersion.HTTP_1_0, UNKNOWN_STATUS, Unpooled.EMPTY_BUFFER, validateHeaders);
127     }
128 
129     @Override
130     protected boolean isDecodingRequest() {
131         return false;
132     }
133 }