js-reverse-dns-ip-filter/index.js

Javascript Reverse DNS IP Filter

const { promises:dnsPromises } = require("dns");

const dico = new Map();

const resolveFQDN = async (addr = '', seekIp = '', useCache = false) => {
    const domains = await dnsPromises.resolveSrv('*.' + addr);
    let ips = [];
    if (useCache) {
        const promises = [];
        for (const domain of domains) {
            if (dico.has(domain.name)) {
                ips.push(dico.get(domain.name));
            } else {
                const pending = dnsPromises.lookup(domain.name)
                                            .then(ip => { dico.set(domain.name, ip); return ip; });
                promises.push(pending);
            }
        }
        ips = ips.concat(await Promise.all(promises));
    } else {
        ips = await Promise.all(domains.map(d => dnsPromises.lookup(d.name)));
    }

    for (const { address } of ips) {
        if (address.includes(seekIp)) {
            return true;
        }
    }

    return false;
};

const search = async (ip, seekIp, useCache = true) => {
    let addresses;

    if (useCache) {
        if (!dico.has(ip)) {
            dico.set(ip, await dnsPromises.reverse(ip));
        }
        addresses = dico.get(ip);
    } else {
        addresses = await dnsPromises.reverse(ip);
    }

    const promises = [];
    for (const addr of addresses) {
        promises.push(resolveFQDN(addr, seekIp, useCache));
    }

    const results = await Promise.all(promises);
    return results.includes(true);
};

module.exports = {
    search
};