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1   /*
2    * Copyright 2020 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.example.dns.dot;
17  
18  import io.netty.bootstrap.Bootstrap;
19  import io.netty.buffer.ByteBufUtil;
20  
21  import io.netty.channel.Channel;
22  import io.netty.channel.ChannelInitializer;
23  import io.netty.channel.ChannelHandlerContext;
24  import io.netty.channel.ChannelPipeline;
25  import io.netty.channel.EventLoopGroup;
26  import io.netty.channel.nio.NioEventLoopGroup;
27  import io.netty.channel.socket.SocketChannel;
28  import io.netty.channel.socket.nio.NioSocketChannel;
29  import io.netty.channel.SimpleChannelInboundHandler;
30  
31  import io.netty.handler.codec.dns.DefaultDnsQuestion;
32  import io.netty.handler.codec.dns.DefaultDnsResponse;
33  import io.netty.handler.codec.dns.DnsQuestion;
34  import io.netty.handler.codec.dns.DnsQuery;
35  import io.netty.handler.codec.dns.DefaultDnsQuery;
36  import io.netty.handler.codec.dns.DnsOpCode;
37  import io.netty.handler.codec.dns.DnsRecord;
38  import io.netty.handler.codec.dns.DnsSection;
39  import io.netty.handler.codec.dns.DnsRecordType;
40  import io.netty.handler.codec.dns.DnsRawRecord;
41  import io.netty.handler.codec.dns.TcpDnsQueryEncoder;
42  import io.netty.handler.codec.dns.TcpDnsResponseDecoder;
43  import io.netty.handler.ssl.SslContext;
44  import io.netty.handler.ssl.SslContextBuilder;
45  import io.netty.util.NetUtil;
46  
47  import java.util.Random;
48  import java.util.concurrent.TimeUnit;
49  
50  public final class DoTClient {
51      private static final String QUERY_DOMAIN = "www.example.com";
52      private static final int DNS_SERVER_PORT = 853;
53      private static final String DNS_SERVER_HOST = "8.8.8.8";
54  
55      private DoTClient() {
56      }
57  
58      private static void handleQueryResp(DefaultDnsResponse msg) {
59          if (msg.count(DnsSection.QUESTION) > 0) {
60              DnsQuestion question = msg.recordAt(DnsSection.QUESTION, 0);
61              System.out.printf("name: %s%n", question.name());
62          }
63          for (int i = 0, count = msg.count(DnsSection.ANSWER); i < count; i++) {
64              DnsRecord record = msg.recordAt(DnsSection.ANSWER, i);
65              if (record.type() == DnsRecordType.A) {
66                  //just print the IP after query
67                  DnsRawRecord raw = (DnsRawRecord) record;
68                  System.out.println(NetUtil.bytesToIpAddress(ByteBufUtil.getBytes(raw.content())));
69              }
70          }
71      }
72  
73      public static void main(String[] args) throws Exception {
74          EventLoopGroup group = new NioEventLoopGroup();
75          try {
76              final SslContext sslContext = SslContextBuilder.forClient()
77                      .protocols("TLSv1.3", "TLSv1.2")
78                      .build();
79  
80              Bootstrap b = new Bootstrap();
81              b.group(group)
82                      .channel(NioSocketChannel.class)
83                      .handler(new ChannelInitializer<SocketChannel>() {
84                          @Override
85                          protected void initChannel(SocketChannel ch) {
86                              ChannelPipeline p = ch.pipeline();
87                              p.addLast(sslContext.newHandler(ch.alloc(), DNS_SERVER_HOST, DNS_SERVER_PORT))
88                                      .addLast(new TcpDnsQueryEncoder())
89                                      .addLast(new TcpDnsResponseDecoder())
90                                      .addLast(new SimpleChannelInboundHandler<DefaultDnsResponse>() {
91                                          @Override
92                                          protected void channelRead0(ChannelHandlerContext ctx, DefaultDnsResponse msg) {
93                                              try {
94                                                  handleQueryResp(msg);
95                                              } finally {
96                                                  ctx.close();
97                                              }
98                                          }
99                                      });
100                         }
101                     });
102             final Channel ch = b.connect(DNS_SERVER_HOST, DNS_SERVER_PORT).sync().channel();
103 
104             int randomID = new Random().nextInt(60000 - 1000) + 1000;
105             DnsQuery query = new DefaultDnsQuery(randomID, DnsOpCode.QUERY)
106                     .setRecord(DnsSection.QUESTION, new DefaultDnsQuestion(QUERY_DOMAIN, DnsRecordType.A));
107             ch.writeAndFlush(query).sync();
108             boolean success = ch.closeFuture().await(10, TimeUnit.SECONDS);
109             if (!success) {
110                 System.err.println("dns query timeout!");
111                 ch.close().sync();
112             }
113         } finally {
114             group.shutdownGracefully();
115         }
116     }
117 }