View Javadoc

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 org.jboss.netty.handler.codec.marshalling;
17  
18  import java.io.ObjectStreamConstants;
19  
20  import org.jboss.marshalling.ByteInput;
21  import org.jboss.marshalling.Unmarshaller;
22  import org.jboss.netty.buffer.ChannelBuffer;
23  import org.jboss.netty.channel.Channel;
24  import org.jboss.netty.channel.ChannelHandlerContext;
25  import org.jboss.netty.channel.ExceptionEvent;
26  import org.jboss.netty.handler.codec.frame.TooLongFrameException;
27  import org.jboss.netty.handler.codec.replay.ReplayingDecoder;
28  import org.jboss.netty.handler.codec.replay.VoidEnum;
29  
30  /**
31   * {@link ReplayingDecoder} which use an {@link Unmarshaller} to read the Object out of the {@link ChannelBuffer}.
32   *
33   * If you can you should use {@link MarshallingDecoder}.
34   *
35   *
36   *
37   */
38  public class CompatibleMarshallingDecoder extends ReplayingDecoder<VoidEnum> {
39      protected final UnmarshallerProvider provider;
40      protected final int maxObjectSize;
41  
42      /**
43       * Create a new instance of {@link CompatibleMarshallingDecoder}.
44       *
45       * @param provider
46       *        the {@link UnmarshallerProvider} which is used to obtain the {@link Unmarshaller}
47       *        for the {@link Channel}
48       * @param maxObjectSize
49       *        the maximal size (in bytes) of the {@link Object} to unmarshal. Once the size is
50       *        exceeded the {@link Channel} will get closed. Use a a maxObjectSize of
51       *        {@link Integer#MAX_VALUE} to disable this. You should only do this if you are sure
52       *        that the received Objects will never be big and the sending side are trusted, as
53       *        this opens the possibility for a DOS-Attack due an {@link OutOfMemoryError}.
54       */
55      public CompatibleMarshallingDecoder(UnmarshallerProvider provider, int maxObjectSize) {
56          this.provider = provider;
57          this.maxObjectSize = maxObjectSize;
58      }
59  
60      @Override
61      protected Object decode(
62              ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer, VoidEnum state) throws Exception {
63          Unmarshaller unmarshaller = provider.getUnmarshaller(ctx);
64          ByteInput input = new ChannelBufferByteInput(buffer);
65          if (maxObjectSize != Integer.MAX_VALUE) {
66              input = new LimitingByteInput(input, maxObjectSize);
67          }
68          try {
69              unmarshaller.start(input);
70              Object obj = unmarshaller.readObject();
71              unmarshaller.finish();
72              return obj;
73          } catch (LimitingByteInput.TooBigObjectException e) {
74              throw new TooLongFrameException("Object to big to unmarshal");
75          } finally {
76              // Call close in a finally block as the ReplayingDecoder will throw an Error if not enough bytes are
77              // readable. This helps to be sure that we do not leak resource
78              unmarshaller.close();
79          }
80      }
81  
82      @Override
83      protected Object decodeLast(ChannelHandlerContext ctx, Channel channel,
84              ChannelBuffer buffer, VoidEnum state)
85              throws Exception {
86          switch (buffer.readableBytes()) {
87          case 0:
88              return null;
89          case 1:
90              // Ignore the last TC_RESET
91              if (buffer.getByte(buffer.readerIndex()) == ObjectStreamConstants.TC_RESET) {
92                  buffer.skipBytes(1);
93                  return null;
94              }
95          }
96  
97          Object decoded = decode(ctx, channel, buffer, state);
98          return decoded;
99      }
100 
101     /**
102      * Calls {@link Channel#close()} if a TooLongFrameException was thrown
103      */
104     @Override
105     public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
106         if (e.getCause() instanceof TooLongFrameException) {
107             e.getChannel().close();
108 
109         } else {
110             super.exceptionCaught(ctx, e);
111         }
112     }
113 }