Node.JS编写的DNS分发器

Node.JS编写的DNS分发器

const dgram = require('dgram');
//获取本地时间字符串
function getDateStr() {
    return (new Date()).toLocaleString();
}
function checkDomainOne(sReq, sDomain) {
    const aReq = sReq.split('.');
    const aDomain = sDomain.split('.');
    const iLen = aDomain.length;
    for (var i = 0; i < iLen; i++) {
        const sReq = aReq.pop();
        if (sReq === undefined) {
            return false;
        }
        const sDom = aDomain.pop();
        if (sDom !== sReq) {
            return false;
        }
    }
    return true;
}
function checkDomainByList(sReq, sList) {
    const aList = sList.split(',');
    for (var i = 0; i < aList.length; i++) {
        const sDomain = aList[i];
        if (checkDomainOne(sReq, sDomain)) {
            return true;
        }
    }
    return false;
}
function getDnsAddrByHost(conf, sReqHost) {
    if (checkDomainByList(sReqHost, conf.domain_gfw)) {
        return '192.168.30.1';
    }
    return '192.168.5.1';
}
function parseHost(_msg) {
    const sMsg = _msg.subarray(12);
    const aHost = [];
    var num = sMsg.readUInt8(0);
    var offset = 1;
    while (num !== 0) {
        aHost.push(sMsg.subarray(offset, offset + num).toString());
        offset += num;
        num = sMsg.readUInt8(offset);
        offset += 1;
    }
    return aHost.join('.');
}
// 创建DNS代理
function proxyDNS(conf) {
    const serverUDP = dgram.createSocket('udp4');
    serverUDP.on('error', (err) => {
        console.error(`[${getDateStr()}] [ERROR] - ${err}`);
    });
    serverUDP.on('message', (msg, rinfo) => {
        const sReqHost = parseHost(msg);
        const dnsAddr = getDnsAddrByHost(conf, sReqHost);
        console.info(`[${getDateStr()}] ${rinfo.address} ${sReqHost} => ${dnsAddr}`);
        const client = dgram.createSocket('udp4');
        client.on('error', (err) => {
            console.error(`[${getDateStr()}] [ERROR] - ${err}`);
            client.close();
        });
        client.on('message', (fbMsg, fbRinfo) => {
            serverUDP.send(fbMsg, rinfo.port, rinfo.address, (err) => {
                if (err) console.error(`[${getDateStr()}] [ERROR] - ${err}`);
            });
            client.close();
        });
        client.send(msg, 53, dnsAddr, (err) => {
            if (err) {
                console.error(`[${getDateStr()}] [ERROR] - ${err}`);
                client.close();
            }
        });
    });
    serverUDP.bind(conf.bind[1], conf.bind[0], () => {
        console.info(`[${getDateStr()}] [INFO] - UDP Server start ${conf.bind[0]}:${conf.bind[1]}`);
    });
    return serverUDP;
}
const conf = {};
conf.bind = ["0.0.0.0", 53];
conf.domain_gfw = 'app.cloudcone.com,facebook.com,fbcdn.net,githubusercontent.com,gstatic.com,gmail.com,google.com,google.com.hk,googleapis.com,googleusercontent.com,googlevideo.com,instagram.com,line.me,line-apps.com,line-scdn.net,messenger.com,naver.jp,tdesktop.com,telegram.org,v2fly.org,youtube.com,ytimg.com';
proxyDNS(conf);

根据域名转发DNS到不同的服务器