关于netty:Java-Netty框架自建DNS代理服务器教程

前言

DNS协定作为着互联网客户端-服务器通信模式得第一关，在当下每天都有成千上亿上网记录产生得当今社会，其重要性天然不可言喻。在国内比拟有名得DNS服务器有电信得114.114.114.114、阿里云得223.5.5.5，DNSPod得119.29.29.29，配置一个好的DNS服务器能够缩短申请响应工夫、升高DNS劫持概率，晋升上网体验。

下面这些都是互联网专用DNS服务器，本文博主教大家应用 Java Netty 自建DNS代理服务器，目前网上对于应用Netty自建DNS服务器得教程参差不齐，大多没有代理步骤，达不到博主想要得代理成果，因此创立此文。

一、自建DNS代理服务器有哪些劣势

域名管制：对于特定域名能够自在管制拜访权限（屏蔽对特定网站拜访）
域名记录：记录局域网内各个主机得域名拜访（记录员工上网记录）
配置内网域名：通过自建DNS服务器能够配置内网域名，节约老本
DNS负载平衡：通过自建DNS服务器能够轻松实现对于拜访域名得负载平衡配置
...

二、自建DNS代理服务器代码

增加域名黑名单文件，resources 文件夹下增加 black_list.txt 文件

google.com.facebook.com.

初始化 BLACK_LIST_DOMAIN

private static final List<String> BLACK_LIST_DOMAIN = new ArrayList<>();    static {        String s;        try (InputStream is = DnsServer.class.getClassLoader().getResourceAsStream("black_list.txt");             BufferedReader br = new BufferedReader(new InputStreamReader(is))) {            while (StrUtil.isNotBlank(s = br.readLine())) {                BLACK_LIST_DOMAIN.add(s);            }        } catch (Exception e) {            log.error(e.getMessage(), e);        }    }

应用 UDP 协定绑定本机53端口，并初始化 ProxyUdp DNS申请代理对象

@Slf4jpublic final class DnsServer {    private static final List<String> BLACK_LIST_DOMAIN = new ArrayList<>();    static {       ...    }    public static void main(String[] args) throws Exception {        ProxyUdp proxyUdp = new ProxyUdp();        proxyUdp.init();        final int[] num = {0};        final NioEventLoopGroup group = new NioEventLoopGroup();        Bootstrap bootstrap = new Bootstrap();        bootstrap.group(group).channel(NioDatagramChannel.class)                .handler(new ChannelInitializer<NioDatagramChannel>() {                    @Override                    protected void initChannel(NioDatagramChannel nioDatagramChannel) {                        nioDatagramChannel.pipeline().addLast(...);                    }                }).option(ChannelOption.SO_BROADCAST, true);        int port = 53;        ChannelFuture future = bootstrap.bind(port).addListener(future1 -> {            log.info("server listening port:{}", port);        });        future.channel().closeFuture().addListener(future1 -> {            if (future.isSuccess()) {                log.info(future.channel().toString());            }        });    }}

给 nioDatagramChannel.pipeline() 增加 ChannelHandler

nioDatagramChannel.pipeline().addLast(new DatagramDnsQueryDecoder());                        nioDatagramChannel.pipeline().addLast(new SimpleChannelInboundHandler<DatagramDnsQuery>() {                            @Override                            protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsQuery msg) {                                try {                                    DefaultDnsQuestion dnsQuestion = msg.recordAt(DnsSection.QUESTION);                                    String name = dnsQuestion.name();                                    log.info(name + ++num[0]);                                    Channel channel = ctx.channel();                                    int id = msg.id();                                    channel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(id))).set(msg);                                    if (BLACK_LIST_DOMAIN.contains(name)) {                                        DnsQuestion question = msg.recordAt(DnsSection.QUESTION);                                        DatagramDnsResponse dnsResponse = getDatagramDnsResponse(msg, id, question);                                        channel.writeAndFlush(dnsResponse);                                        return;                                    }                                    proxyUdp.send(name, msg.id(), channel);                                } catch (Exception e) {                                    log.error(e.getMessage(), e);                                }                            }                            private DatagramDnsResponse getDatagramDnsResponse(DatagramDnsQuery msg, int id, DnsQuestion question) {                                DatagramDnsResponse dnsResponse = new DatagramDnsResponse(msg.recipient(), msg.sender(), id);                                dnsResponse.addRecord(DnsSection.QUESTION, question);                                DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord(                                        question.name(),                                        DnsRecordType.A, 600, Unpooled.wrappedBuffer(new byte[]{(byte) 192, (byte) 168, 1, 1}));                                dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer);                                return dnsResponse;                            }                            @Override                            public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) {                                log.error(e.getMessage(), e);                            }                        });                        nioDatagramChannel.pipeline().addLast(new DatagramDnsResponseEncoder());

在 new SimpleChannelInboundHandler<DatagramDnsQuery>() 中解析客户端DNS查问报文, 获取拜访域名信息，如果拜访域名在黑名单中，则通过 getDatagramDnsResponse() 间接返回 192.168.1.1 的DNS响应报文，反之则通过 proxyUdp 对象转发DNS查问。

ProxyUdp 作为DNS查问代理类会通过 send(String domain, int id, Channel serverChannel) 办法传入DnsServer类收到的拜访域名、DNS事务ID、serverChannel。随后包装拜访域名申请DNS服务器114.114.114.114，最初通过 new SimpleChannelInboundHandler<DatagramDnsResponse>() 将收到的DNS响应报文通过上一步传入得 serverChannel 输入到客户端。

@Slf4jclass ProxyUdp {    private Channel serverChannel;    private Channel proxyChannel;    public void init() throws InterruptedException {        EventLoopGroup proxyGroup = new NioEventLoopGroup();        Bootstrap b = new Bootstrap();        b.group(proxyGroup)                .channel(NioDatagramChannel.class)                .handler(new ChannelInitializer<DatagramChannel>() {                    @Override                    protected void initChannel(DatagramChannel ch) {                        ChannelPipeline p = ch.pipeline();                        p.addLast(new DatagramDnsQueryEncoder())                                .addLast(new DatagramDnsResponseDecoder())                                .addLast(new SimpleChannelInboundHandler<DatagramDnsResponse>() {                                    @Override                                    public void channelActive(ChannelHandlerContext ctx) {                                        log.info(ctx.channel().toString());                                    }                                    @Override                                    protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsResponse msg) {                                        DatagramDnsQuery dnsQuery = localChannel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(msg.id()))).get();                                        DnsQuestion question = msg.recordAt(DnsSection.QUESTION);                                        DatagramDnsResponse dnsResponse = new DatagramDnsResponse(dnsQuery.recipient(), dnsQuery.sender(), msg.id());                                        dnsResponse.addRecord(DnsSection.QUESTION, question);                                        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;                                                DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord(                                                        question.name(),                                                        DnsRecordType.A, 600, Unpooled.wrappedBuffer(ByteBufUtil.getBytes(raw.content())));                                                dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer);                                            }                                        }                                        serverChannel.writeAndFlush(dnsResponse);                                    }                                    @Override                                    public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) {                                        log.error(e.getMessage(), e);                                    }                                });                    }                });        proxyChannel = b.bind(0).sync().addListener(future1 -> {            log.info("绑定胜利");        }).channel();    }    public void send(String domain, int id, Channel serverChannel) {        this.serverChannel = serverChannel;        DnsQuery query = new DatagramDnsQuery(null, new InetSocketAddress("114.114.114.114", 53), id).setRecord(                DnsSection.QUESTION,                new DefaultDnsQuestion(domain, DnsRecordType.A));        this.proxyChannel.writeAndFlush(query);    }}

自建DNS服务器全副代码

@Slf4jpublic final class DnsServer {    private static final List<String> BLACK_LIST_DOMAIN = new ArrayList<>();    static {        String s;        try (InputStream is = DnsServer.class.getClassLoader().getResourceAsStream("black_list.txt");             BufferedReader br = new BufferedReader(new InputStreamReader(is))) {            while (StrUtil.isNotBlank(s = br.readLine())) {                BLACK_LIST_DOMAIN.add(s);            }        } catch (Exception e) {            log.error(e.getMessage(), e);        }    }    public static void main(String[] args) throws Exception {        ProxyUdp proxyUdp = new ProxyUdp();        proxyUdp.init();        final int[] num = {0};        final NioEventLoopGroup group = new NioEventLoopGroup();        Bootstrap bootstrap = new Bootstrap();        bootstrap.group(group).channel(NioDatagramChannel.class)                .handler(new ChannelInitializer<NioDatagramChannel>() {                    @Override                    protected void initChannel(NioDatagramChannel nioDatagramChannel) {                        nioDatagramChannel.pipeline().addLast(new DatagramDnsQueryDecoder());                        nioDatagramChannel.pipeline().addLast(new SimpleChannelInboundHandler<DatagramDnsQuery>() {                            @Override                            protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsQuery msg) {                                try {                                    DefaultDnsQuestion dnsQuestion = msg.recordAt(DnsSection.QUESTION);                                    String name = dnsQuestion.name();                                    log.info(name + ++num[0]);                                    Channel channel = ctx.channel();                                    int id = msg.id();                                    channel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(id))).set(msg);                                    if (BLACK_LIST_DOMAIN.contains(name)) {                                        DnsQuestion question = msg.recordAt(DnsSection.QUESTION);                                        DatagramDnsResponse dnsResponse = getDatagramDnsResponse(msg, id, question);                                        channel.writeAndFlush(dnsResponse);                                        return;                                    }                                    proxyUdp.send(name, msg.id(), channel);                                } catch (Exception e) {                                    log.error(e.getMessage(), e);                                }                            }                            private DatagramDnsResponse getDatagramDnsResponse(DatagramDnsQuery msg, int id, DnsQuestion question) {                                DatagramDnsResponse dnsResponse = new DatagramDnsResponse(msg.recipient(), msg.sender(), id);                                dnsResponse.addRecord(DnsSection.QUESTION, question);                                // just print the IP after query                                DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord(                                        question.name(),                                        DnsRecordType.A, 600, Unpooled.wrappedBuffer(new byte[]{(byte) 192, (byte) 168, 1, 1}));                                dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer);                                return dnsResponse;                            }                            @Override                            public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) {                                log.error(e.getMessage(), e);                            }                        });                        nioDatagramChannel.pipeline().addLast(new DatagramDnsResponseEncoder());                    }                }).option(ChannelOption.SO_BROADCAST, true);        int port = 553;        ChannelFuture future = bootstrap.bind(port).addListener(future1 -> {            log.info("server listening port:{}", port);        });        future.channel().closeFuture().addListener(future1 -> {            if (future.isSuccess()) {                log.info(future.channel().toString());            }        });    }}@Slf4jclass ProxyUdp {    private Channel localChannel;    private Channel proxyChannel;    public void init() throws InterruptedException {        EventLoopGroup proxyGroup = new NioEventLoopGroup();        Bootstrap b = new Bootstrap();        b.group(proxyGroup)                .channel(NioDatagramChannel.class)                .handler(new ChannelInitializer<DatagramChannel>() {                    @Override                    protected void initChannel(DatagramChannel ch) {                        ChannelPipeline p = ch.pipeline();                        p.addLast(new DatagramDnsQueryEncoder())                                .addLast(new DatagramDnsResponseDecoder())                                .addLast(new SimpleChannelInboundHandler<DatagramDnsResponse>() {                                    @Override                                    public void channelActive(ChannelHandlerContext ctx) {                                        log.info(ctx.channel().toString());                                    }                                    @Override                                    protected void channelRead0(ChannelHandlerContext ctx, DatagramDnsResponse msg) {                                        DatagramDnsQuery dnsQuery = localChannel.attr(AttributeKey.<DatagramDnsQuery>valueOf(String.valueOf(msg.id()))).get();                                        DnsQuestion question = msg.recordAt(DnsSection.QUESTION);                                        DatagramDnsResponse dnsResponse = new DatagramDnsResponse(dnsQuery.recipient(), dnsQuery.sender(), msg.id());                                        dnsResponse.addRecord(DnsSection.QUESTION, question);                                        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;                                                DefaultDnsRawRecord queryAnswer = new DefaultDnsRawRecord(                                                        question.name(),                                                        DnsRecordType.A, 600, Unpooled.wrappedBuffer(ByteBufUtil.getBytes(raw.content())));                                                dnsResponse.addRecord(DnsSection.ANSWER, queryAnswer);                                            }                                        }                                        localChannel.writeAndFlush(dnsResponse);                                    }                                    @Override                                    public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) {                                        log.error(e.getMessage(), e);                                    }                                });                    }                });        proxyChannel = b.bind(0).sync().addListener(future1 -> {            log.info("绑定胜利");        }).channel();    }    public void send(String domain, int id, Channel localChannel) {        this.localChannel = localChannel;        DnsQuery query = new DatagramDnsQuery(null, new InetSocketAddress("114.114.114.114", 53), id).setRecord(                DnsSection.QUESTION,                new DefaultDnsQuestion(domain, DnsRecordType.A));        this.proxyChannel.writeAndFlush(query);    }}

三、本地测试

批改本机DNS设置(win11)，批改首选、备选DNS地址为127.0.0.1

关上命令行工具，执行DNS缓存革除命令 ipconfig/flushdns

自此就能够关上浏览器拜访罕用网站，看是否能失常拜访，来验证自建的DNS服务器成果了