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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.rtsp;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.handler.codec.TooLongFrameException;
20  import io.netty.handler.codec.http.HttpMessage;
21  import io.netty.handler.codec.http.HttpObjectDecoder;
22  
23  /**
24   * Decodes {@link ByteBuf}s into RTSP messages represented in
25   * {@link HttpMessage}s.
26   * <p>
27   * <h3>Parameters that prevents excessive memory consumption</h3>
28   * <table border="1">
29   * <tr>
30   * <th>Name</th><th>Meaning</th>
31   * </tr>
32   * <tr>
33   * <td>{@code maxInitialLineLength}</td>
34   * <td>The maximum length of the initial line
35   *     (e.g. {@code "SETUP / RTSP/1.0"} or {@code "RTSP/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 maxContentLength}</td>
46   * <td>The maximum length of the content.  If the content length exceeds this
47   *     value, a {@link TooLongFrameException} will be raised.</td>
48   * </tr>
49   * </table>
50   */
51  public abstract class RtspObjectDecoder extends HttpObjectDecoder {
52  
53      /**
54       * Creates a new instance with the default
55       * {@code maxInitialLineLength (4096)}, {@code maxHeaderSize (8192)}, and
56       * {@code maxContentLength (8192)}.
57       */
58      protected RtspObjectDecoder() {
59          this(4096, 8192, 8192);
60      }
61  
62      /**
63       * Creates a new instance with the specified parameters.
64       */
65      protected RtspObjectDecoder(int maxInitialLineLength, int maxHeaderSize, int maxContentLength) {
66          super(maxInitialLineLength, maxHeaderSize, maxContentLength * 2, false);
67      }
68  
69      protected RtspObjectDecoder(
70              int maxInitialLineLength, int maxHeaderSize, int maxContentLength, boolean validateHeaders) {
71          super(maxInitialLineLength, maxHeaderSize, maxContentLength * 2, false, validateHeaders);
72      }
73  
74      @Override
75      protected boolean isContentAlwaysEmpty(HttpMessage msg) {
76          // Unlike HTTP, RTSP always assumes zero-length body if Content-Length
77          // header is absent.
78          boolean empty = super.isContentAlwaysEmpty(msg);
79          if (empty) {
80              return true;
81          }
82          if (!msg.headers().contains(RtspHeaderNames.CONTENT_LENGTH)) {
83              return true;
84          }
85          return empty;
86      }
87  }