Add DoT and TCP DNS Client Example (#10256)

Motivation:

[DNS-over-TLS (DoT)](https://tools.ietf.org/html/rfc7858.html) encrypts DNS queries and sends it over TLS connection to make sure queries are secure in transit.

[TCP DNS](https://tools.ietf.org/html/rfc7766) sends DNS queries over TCP connection (unencrypted).

Modification:

Add DNS-over-TLS (DoT) Client Example which uses TLSv1.2 and TLSv1.3.
Add TCP DNS Client Example

Result:

DNS-over-TLS (DoT) Client Example
TCP DNS Client Example
This commit is contained in:
Aayush Atharva 2020-05-07 18:56:14 +05:30 committed by Norman Maurer
parent 73b4179b8d
commit ff9b2ac668
2 changed files with 230 additions and 0 deletions

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/*
* Copyright 2020 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:
*
* http://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.dot;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.dns.DefaultDnsQuestion;
import io.netty.handler.codec.dns.DefaultDnsResponse;
import io.netty.handler.codec.dns.DnsQuestion;
import io.netty.handler.codec.dns.DnsQuery;
import io.netty.handler.codec.dns.DefaultDnsQuery;
import io.netty.handler.codec.dns.DnsOpCode;
import io.netty.handler.codec.dns.DnsRecord;
import io.netty.handler.codec.dns.DnsSection;
import io.netty.handler.codec.dns.DnsRecordType;
import io.netty.handler.codec.dns.DnsRawRecord;
import io.netty.handler.codec.dns.TcpDnsQueryEncoder;
import io.netty.handler.codec.dns.TcpDnsResponseDecoder;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.util.NetUtil;
import java.util.Random;
import java.util.concurrent.TimeUnit;
public final class DoTClient {
private static final String QUERY_DOMAIN = "www.example.com";
private static final int DNS_SERVER_PORT = 853;
private static final String DNS_SERVER_HOST = "8.8.8.8";
private DoTClient() {
}
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())));
}
}
}
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
final SslContext sslContext = SslContextBuilder.forClient()
.protocols("TLSv1.3", "TLSv1.2")
.build();
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) {
ChannelPipeline p = ch.pipeline();
p.addLast(sslContext.newHandler(ch.alloc(), DNS_SERVER_HOST, DNS_SERVER_PORT))
.addLast(new TcpDnsQueryEncoder())
.addLast(new TcpDnsResponseDecoder())
.addLast(new SimpleChannelInboundHandler<DefaultDnsResponse>() {
@Override
protected void messageReceived(
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();
}
}
}

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/*
* Copyright 2020 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:
*
* http://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.buffer.ByteBufUtil;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.dns.DefaultDnsQuestion;
import io.netty.handler.codec.dns.DefaultDnsResponse;
import io.netty.handler.codec.dns.DnsQuestion;
import io.netty.handler.codec.dns.DnsQuery;
import io.netty.handler.codec.dns.DefaultDnsQuery;
import io.netty.handler.codec.dns.DnsOpCode;
import io.netty.handler.codec.dns.DnsRecord;
import io.netty.handler.codec.dns.DnsSection;
import io.netty.handler.codec.dns.DnsRecordType;
import io.netty.handler.codec.dns.DnsRawRecord;
import io.netty.handler.codec.dns.TcpDnsQueryEncoder;
import io.netty.handler.codec.dns.TcpDnsResponseDecoder;
import io.netty.util.NetUtil;
import java.util.Random;
import java.util.concurrent.TimeUnit;
public final class TcpDnsClient {
private static final String QUERY_DOMAIN = "www.example.com";
private static final int DNS_SERVER_PORT = 53;
private static final String DNS_SERVER_HOST = "8.8.8.8";
private TcpDnsClient() {
}
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())));
}
}
}
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) {
ChannelPipeline p = ch.pipeline();
p.addLast(new TcpDnsQueryEncoder())
.addLast(new TcpDnsResponseDecoder())
.addLast(new SimpleChannelInboundHandler<DefaultDnsResponse>() {
@Override
protected void messageReceived(
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();
}
}
}