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1   /*
2    * Copyright 2015 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.rtsp;
17  
18  import java.util.regex.Pattern;
19  
20  import io.netty.buffer.Unpooled;
21  import io.netty.handler.codec.http.DefaultFullHttpRequest;
22  import io.netty.handler.codec.http.DefaultFullHttpResponse;
23  import io.netty.handler.codec.http.DefaultHttpRequest;
24  import io.netty.handler.codec.http.DefaultHttpResponse;
25  import io.netty.handler.codec.http.HttpDecoderConfig;
26  import io.netty.handler.codec.http.HttpMessage;
27  import io.netty.handler.codec.http.HttpObjectDecoder;
28  import io.netty.handler.codec.http.HttpResponseStatus;
29  
30  /**
31   * Decodes {@link io.netty.buffer.ByteBuf}s into RTSP messages represented in
32   * {@link HttpMessage}s.
33   * <p>
34   * <h3>Parameters that prevents excessive memory consumption</h3>
35   * <table border="1">
36   * <tr>
37   * <th>Name</th><th>Meaning</th>
38   * </tr>
39   * <tr>
40   * <td>{@code maxInitialLineLength}</td>
41   * <td>The maximum length of the initial line
42   *     (e.g. {@code "SETUP / RTSP/1.0"} or {@code "RTSP/1.0 200 OK"})
43   *     If the length of the initial line exceeds this value, a
44   *     {@link io.netty.handler.codec.TooLongFrameException} will be raised.</td>
45   * </tr>
46   * <tr>
47   * <td>{@code maxHeaderSize}</td>
48   * <td>The maximum length of all headers. If the sum of the length of each
49   *     header exceeds this value, a {@link io.netty.handler.codec.TooLongFrameException} will be
50   *     raised.</td>
51   * </tr>
52   * <tr>
53   * <td>{@code maxContentLength}</td>
54   * <td>The maximum length of the content.  If the content length exceeds this
55   *     value, a {@link io.netty.handler.codec.TooLongFrameException} will be raised.</td>
56   * </tr>
57   * </table>
58   */
59  public class RtspDecoder extends HttpObjectDecoder {
60      /**
61       * Status code for unknown responses.
62       */
63      private static final HttpResponseStatus UNKNOWN_STATUS =
64              new HttpResponseStatus(999, "Unknown");
65      /**
66       * True if the message to decode is a request.
67       * False if the message to decode is a response.
68       */
69      private boolean isDecodingRequest;
70  
71      /**
72       * Regex used on first line in message to detect if it is a response.
73       */
74      private static final Pattern versionPattern = Pattern.compile("RTSP/\\d\\.\\d");
75  
76      /**
77       * Constant for default max content length.
78       */
79      public static final int DEFAULT_MAX_CONTENT_LENGTH = 8192;
80  
81      /**
82       * Creates a new instance with the default
83       * {@code maxInitialLineLength (4096)}, {@code maxHeaderSize (8192)}, and
84       * {@code maxContentLength (8192)}.
85       */
86      public RtspDecoder() {
87          this(DEFAULT_MAX_INITIAL_LINE_LENGTH,
88               DEFAULT_MAX_HEADER_SIZE,
89               DEFAULT_MAX_CONTENT_LENGTH);
90      }
91  
92      /**
93       * Creates a new instance with the specified parameters.
94       * @param maxInitialLineLength The max allowed length of initial line
95       * @param maxHeaderSize The max allowed size of header
96       * @param maxContentLength The max allowed content length
97       */
98      public RtspDecoder(final int maxInitialLineLength,
99                         final int maxHeaderSize,
100                        final int maxContentLength) {
101         super(new HttpDecoderConfig()
102                 .setMaxInitialLineLength(maxInitialLineLength)
103                 .setMaxHeaderSize(maxHeaderSize)
104                 .setMaxChunkSize(maxContentLength * 2)
105                 .setChunkedSupported(false));
106     }
107 
108     /**
109      * Creates a new instance with the specified parameters.
110      * @param maxInitialLineLength The max allowed length of initial line
111      * @param maxHeaderSize The max allowed size of header
112      * @param maxContentLength The max allowed content length
113      * @param validateHeaders Set to true if headers should be validated
114      * @deprecated Use the {@link #RtspDecoder(HttpDecoderConfig)} constructor instead,
115      * or the {@link #RtspDecoder(int, int, int)} to always enable header validation.
116      */
117     @Deprecated
118     public RtspDecoder(final int maxInitialLineLength,
119                        final int maxHeaderSize,
120                        final int maxContentLength,
121                        final boolean validateHeaders) {
122         super(new HttpDecoderConfig()
123                 .setMaxInitialLineLength(maxInitialLineLength)
124                 .setMaxHeaderSize(maxHeaderSize)
125                 .setMaxChunkSize(maxContentLength * 2)
126                 .setChunkedSupported(false)
127                 .setValidateHeaders(validateHeaders));
128     }
129 
130     /**
131      * Creates a new instance with the specified configuration.
132      */
133     public RtspDecoder(HttpDecoderConfig config) {
134         super(config.clone()
135                 .setMaxChunkSize(2 * config.getMaxChunkSize())
136                 .setChunkedSupported(false));
137     }
138 
139     @Override
140     protected HttpMessage createMessage(final String[] initialLine)
141             throws Exception {
142         // If the first element of the initial line is a version string then
143         // this is a response
144         if (versionPattern.matcher(initialLine[0]).matches()) {
145             isDecodingRequest = false;
146             return new DefaultHttpResponse(RtspVersions.valueOf(initialLine[0]),
147                 new HttpResponseStatus(Integer.parseInt(initialLine[1]),
148                                        initialLine[2]),
149                 headersFactory);
150         } else {
151             isDecodingRequest = true;
152             return new DefaultHttpRequest(RtspVersions.valueOf(initialLine[2]),
153                     RtspMethods.valueOf(initialLine[0]),
154                     initialLine[1],
155                     headersFactory);
156         }
157     }
158 
159     @Override
160     protected boolean isContentAlwaysEmpty(final HttpMessage msg) {
161         // Unlike HTTP, RTSP always assumes zero-length body if Content-Length
162         // header is absent.
163         return super.isContentAlwaysEmpty(msg) || !msg.headers().contains(RtspHeaderNames.CONTENT_LENGTH);
164     }
165 
166     @Override
167     protected HttpMessage createInvalidMessage() {
168         if (isDecodingRequest) {
169             return new DefaultFullHttpRequest(RtspVersions.RTSP_1_0,
170                        RtspMethods.OPTIONS, "/bad-request", Unpooled.buffer(0), headersFactory, trailersFactory);
171         } else {
172             return new DefaultFullHttpResponse(
173                     RtspVersions.RTSP_1_0, UNKNOWN_STATUS, Unpooled.buffer(0), headersFactory, trailersFactory);
174         }
175     }
176 
177     @Override
178     protected boolean isDecodingRequest() {
179         return isDecodingRequest;
180     }
181 }