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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.dns;
17  
18  import io.netty.channel.ChannelHandler;
19  import io.netty.channel.ChannelHandlerContext;
20  import io.netty.channel.socket.DatagramPacket;
21  import io.netty.handler.codec.CorruptedFrameException;
22  import io.netty.handler.codec.MessageToMessageDecoder;
23  
24  import java.net.InetSocketAddress;
25  import java.util.List;
26  
27  /**
28   * Decodes a {@link DatagramPacket} into a {@link DatagramDnsResponse}.
29   */
30  @ChannelHandler.Sharable
31  public class DatagramDnsResponseDecoder extends MessageToMessageDecoder<DatagramPacket> {
32  
33      private final DnsResponseDecoder<InetSocketAddress> responseDecoder;
34  
35      /**
36       * Creates a new decoder with {@linkplain DnsRecordDecoder#DEFAULT the default record decoder}.
37       */
38      public DatagramDnsResponseDecoder() {
39          this(DnsRecordDecoder.DEFAULT);
40      }
41  
42      /**
43       * Creates a new decoder with the specified {@code recordDecoder}.
44       */
45      public DatagramDnsResponseDecoder(DnsRecordDecoder recordDecoder) {
46          super(DatagramPacket.class);
47          this.responseDecoder = new DnsResponseDecoder<InetSocketAddress>(recordDecoder) {
48              @Override
49              protected DnsResponse newResponse(InetSocketAddress sender, InetSocketAddress recipient,
50                                                int id, DnsOpCode opCode, DnsResponseCode responseCode) {
51                  return new DatagramDnsResponse(sender, recipient, id, opCode, responseCode);
52              }
53          };
54      }
55  
56      @Override
57      protected void decode(ChannelHandlerContext ctx, DatagramPacket packet, List<Object> out) throws Exception {
58          try {
59              out.add(decodeResponse(ctx, packet));
60          } catch (IndexOutOfBoundsException e) {
61              throw new CorruptedFrameException("Unable to decode response", e);
62          }
63      }
64  
65      protected DnsResponse decodeResponse(ChannelHandlerContext ctx, DatagramPacket packet) throws Exception {
66          return responseDecoder.decode(packet.sender(), packet.recipient(), packet.content());
67      }
68  }