150 lines
4.9 KiB
JavaScript
150 lines
4.9 KiB
JavaScript
// 引入UDP模块和dns-packet模块用于解析和构建DNS数据包
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import dgram from 'dgram';
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import dnsPacket from 'dns-packet';
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import { records } from './dns-records.js';
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// 创建UDP服务器，监听53端口（DNS默认端口）
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const server = dgram.createSocket('udp4');
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const PORT = 53;
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// 处理服务器异常
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server.on('error', (err) => {
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console.error(`服务器异常：\n${err.stack}`);
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server.close();
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});
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// 处理收到的DNS查询消息
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server.on('message', (msg, rinfo) => {
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console.log(`收到来自 ${rinfo.address}:${rinfo.port} 的DNS查询`);
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// 解析DNS查询包
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const request = dnsPacket.decode(msg);
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// 确保至少有一个问题（question）
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if (!request.questions || request.questions.length === 0) {
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return;
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}
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const question = request.questions[0];
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console.log(`查询的域名: ${question.name}, 类型: ${question.type}`);
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// 只处理A记录（IPv4地址）查询，其他类型直接忽略
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if (question.type !== 'A') {
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// 对于非A记录查询，可以不响应或发送适当的错误
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return;
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}
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const domain = question.name;
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const ip = records[domain]; // 从本地记录查找域名对应的IP
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let response;
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if (ip) {
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// 本地有记录，直接构造响应包返回
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console.log(`为 ${domain} 找到IP: ${ip}`);
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response = dnsPacket.encode({
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type: 'response',
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id: request.id,
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flags: dnsPacket.AUTHORITATIVE_ANSWER,
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questions: request.questions,
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answers: [{
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type: 'A',
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class: 'IN',
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name: domain,
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ttl: 300, // Time-to-live
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data: ip,
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}],
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});
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// 发送响应给客户端
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server.send(response, rinfo.port, rinfo.address, (err) => {
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if (err) {
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console.error('发送响应失败:', err);
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} else {
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console.log(`已向 ${rinfo.address}:${rinfo.port} 发送响应`);
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}
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});
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} else {
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// 本地无记录，尝试多个上游DNS服务器
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queryUpstreams(msg, rinfo, request, request.questions);
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}
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});
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// 上游DNS服务器列表，可根据需要添加或调整
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const upstreamServers = [
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{ address: '114.114.114.114', port: 53 },// 114DNS
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{ address: '223.5.5.5', port: 53 }, // 阿里DNS
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{ address: '119.29.29.29', port: 53 }, // 腾讯DNSPod
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{ address: '180.76.76.76', port: 53 }, // 百度DNS
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{ address: '1.2.4.8', port: 53 }, // CNNIC SDNS
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{ address: '8.8.8.8', port: 53 },
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{ address: '1.1.1.1', port: 53 }
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];
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/**
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* 依次尝试多个上游DNS服务器，直到有一个返回响应或全部失败
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* @param {*} msg 原始DNS查询包
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* @param {*} rinfo 客户端信息
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* @param {*} request 解析后的DNS请求对象
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* @param {*} questions DNS查询问题列表
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* @param {*} tryIndex 当前尝试的上游DNS索引
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*/
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function queryUpstreams(msg, rinfo, request, questions, tryIndex = 0) {
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if (tryIndex >= upstreamServers.length) {
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// 所有上游DNS都失败，返回NXDOMAIN（域名不存在）
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const response = dnsPacket.encode({
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type: 'response',
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id: request.id,
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flags: dnsPacket.AUTHORITATIVE_ANSWER | dnsPacket.RECURSION_AVAILABLE,
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questions: questions,
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rcode: 'NXDOMAIN'
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});
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server.send(response, rinfo.port, rinfo.address);
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return;
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}
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const { address, port } = upstreamServers[tryIndex];
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const upstreamSocket = dgram.createSocket('udp4'); // 创建临时UDP socket用于与上游DNS通信
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let responded = false; // 标记是否已收到上游响应
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console.log(`No Local DNS Record, Try Upstream DNS: ${address}`);
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// 向当前上游DNS发送查询包
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upstreamSocket.send(msg, port, address, (err) => {
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if (err) {
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// 发送失败，尝试下一个上游DNS
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upstreamSocket.close();
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queryUpstreams(msg, rinfo, request, questions, tryIndex + 1);
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}
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});
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// 监听上游DNS的响应
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upstreamSocket.on('message', (upstreamMsg) => {
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if (!responded) {
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responded = true;
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// 收到响应后，直接转发给客户端
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server.send(upstreamMsg, rinfo.port, rinfo.address, (err) => {
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if (err) {
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console.error('转发上游DNS响应失败:', err);
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} else {
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console.log(`已将上游DNS(${address})响应转发给 ${rinfo.address}:${rinfo.port}`);
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}
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upstreamSocket.close(); // 关闭临时socket
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});
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}
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});
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// 超时处理，若2秒内未收到响应则尝试下一个上游DNS
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setTimeout(() => {
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if (!responded) {
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upstreamSocket.close();
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queryUpstreams(msg, rinfo, request, questions, tryIndex + 1);
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}
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}, 2000);
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}
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// 服务器启动监听
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server.on('listening', () => {
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const address = server.address();
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console.log(`DNS 服务器正在监听 ${address.address}:${address.port}`);
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});
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// 绑定53端口，Windows下需管理员权限
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server.bind(PORT, () => {
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if (process.platform === 'win32') {
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console.log('在 Windows 上运行，请确保您有管理员权限来绑定到53端口。');
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}
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});
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