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1   /*
2    * Copyright 2021 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.netty5.handler.codec.dns;
17  
18  import io.netty5.buffer.api.Buffer;
19  import io.netty5.channel.ChannelHandlerContext;
20  import io.netty5.handler.codec.LengthFieldBasedFrameDecoder;
21  import io.netty5.util.internal.UnstableApi;
22  
23  import static java.util.Objects.requireNonNull;
24  
25  @UnstableApi
26  public final class TcpDnsQueryDecoder extends LengthFieldBasedFrameDecoder {
27      private final DnsRecordDecoder decoder;
28  
29      /**
30       * Creates a new decoder with {@linkplain DnsRecordDecoder#DEFAULT the default record decoder}.
31       */
32      public TcpDnsQueryDecoder() {
33          this(DnsRecordDecoder.DEFAULT, 65535);
34      }
35  
36      /**
37       * Creates a new decoder with the specified {@code decoder}.
38       */
39      public TcpDnsQueryDecoder(DnsRecordDecoder decoder, int maxFrameLength) {
40          super(maxFrameLength, 0, 2, 0, 2);
41          this.decoder = requireNonNull(decoder, "decoder");
42      }
43  
44      @Override
45      protected Object decode0(ChannelHandlerContext ctx, Buffer in) throws Exception {
46          Buffer frame = (Buffer) super.decode0(ctx, in);
47          if (frame == null) {
48              return null;
49          }
50  
51          return DnsMessageUtil.decodeDnsQuery(decoder, ctx.bufferAllocator(), frame.split(), DefaultDnsQuery::new);
52      }
53  }