io.netty.example.dns.tcp.TcpDnsServer Maven / Gradle / Ivy
/*
* Copyright 2021 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.example.dns.tcp;
import io.netty.bootstrap.Bootstrap;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBufUtil;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.dns.DefaultDnsQuery;
import io.netty.handler.codec.dns.DefaultDnsQuestion;
import io.netty.handler.codec.dns.DefaultDnsRawRecord;
import io.netty.handler.codec.dns.DefaultDnsResponse;
import io.netty.handler.codec.dns.DnsOpCode;
import io.netty.handler.codec.dns.DnsQuery;
import io.netty.handler.codec.dns.DnsQuestion;
import io.netty.handler.codec.dns.DnsRawRecord;
import io.netty.handler.codec.dns.DnsRecord;
import io.netty.handler.codec.dns.DnsRecordType;
import io.netty.handler.codec.dns.DnsSection;
import io.netty.handler.codec.dns.TcpDnsQueryDecoder;
import io.netty.handler.codec.dns.TcpDnsQueryEncoder;
import io.netty.handler.codec.dns.TcpDnsResponseDecoder;
import io.netty.handler.codec.dns.TcpDnsResponseEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.util.NetUtil;
import java.util.Random;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public final class TcpDnsServer {
private static final String QUERY_DOMAIN = "www.example.com";
private static final int DNS_SERVER_PORT = 53;
private static final String DNS_SERVER_HOST = "127.0.0.1";
private static final byte[] QUERY_RESULT = new byte[]{(byte) 192, (byte) 168, 1, 1};
public static void main(String[] args) throws Exception {
ServerBootstrap bootstrap = new ServerBootstrap().group(new NioEventLoopGroup(1),
new NioEventLoopGroup())
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer() {
@Override
protected void initChannel(Channel ch) throws Exception {
ch.pipeline().addLast(new TcpDnsQueryDecoder(), new TcpDnsResponseEncoder(),
new SimpleChannelInboundHandler() {
@Override
protected void channelRead0(ChannelHandlerContext ctx,
DnsQuery msg) throws Exception {
DnsQuestion question = msg.recordAt(DnsSection.QUESTION);
System.out.println("Query domain: " + question);
//always return 192.168.1.1
ctx.writeAndFlush(newResponse(msg, question, 600, QUERY_RESULT));
}
private DefaultDnsResponse newResponse(DnsQuery query,
DnsQuestion question,
long ttl, byte[]... addresses) {
DefaultDnsResponse response = new DefaultDnsResponse(query.id());
response.addRecord(DnsSection.QUESTION, question);
for (byte[] address : addresses) {
DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord(
question.name(),
DnsRecordType.A, ttl, Unpooled.wrappedBuffer(address));
response.addRecord(DnsSection.ANSWER, queryAnswer);
}
return response;
}
});
}
});
final Channel channel = bootstrap.bind(DNS_SERVER_PORT).channel();
Executors.newSingleThreadScheduledExecutor().schedule(new Runnable() {
@Override
public void run() {
try {
clientQuery();
channel.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}, 1000, TimeUnit.MILLISECONDS);
channel.closeFuture().sync();
}
// copy from TcpDnsClient.java
private static void clientQuery() throws Exception {
NioEventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer() {
@Override
protected void initChannel(SocketChannel ch) {
ch.pipeline().addLast(new TcpDnsQueryEncoder())
.addLast(new TcpDnsResponseDecoder())
.addLast(new SimpleChannelInboundHandler() {
@Override
protected void channelRead0(ChannelHandlerContext ctx, DefaultDnsResponse msg) {
try {
handleQueryResp(msg);
} finally {
ctx.close();
}
}
});
}
});
final Channel ch = b.connect(DNS_SERVER_HOST, DNS_SERVER_PORT).sync().channel();
int randomID = new Random().nextInt(60000 - 1000) + 1000;
DnsQuery query = new DefaultDnsQuery(randomID, DnsOpCode.QUERY)
.setRecord(DnsSection.QUESTION, new DefaultDnsQuestion(QUERY_DOMAIN, DnsRecordType.A));
ch.writeAndFlush(query).sync();
boolean success = ch.closeFuture().await(10, TimeUnit.SECONDS);
if (!success) {
System.err.println("dns query timeout!");
ch.close().sync();
}
} finally {
group.shutdownGracefully();
}
}
private static void handleQueryResp(DefaultDnsResponse msg) {
if (msg.count(DnsSection.QUESTION) > 0) {
DnsQuestion question = msg.recordAt(DnsSection.QUESTION, 0);
System.out.printf("name: %s%n", question.name());
}
for (int i = 0, count = msg.count(DnsSection.ANSWER); i < count; i++) {
DnsRecord record = msg.recordAt(DnsSection.ANSWER, i);
if (record.type() == DnsRecordType.A) {
//just print the IP after query
DnsRawRecord raw = (DnsRawRecord) record;
System.out.println(NetUtil.bytesToIpAddress(ByteBufUtil.getBytes(raw.content())));
}
}
}
}
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