Create a allow|white-list for hosts

[mStirner]

Allow to define a (white|allow)-list, which a connector should bridge connection requests to.
Draft:

const { BlockList } = require("net");
const dns = require("dns");
const { readFileSync } = require("fs");


const allowlist = new BlockList();

const ALLOWS = JSON.parse(readFileSync("./allowlist.json"));


ALLOWS.forEach((host) => {
    if (host.includes("/")) {

        let [net, prefix] = host.split("/");
        allowlist.addSubnet(net, parseInt(prefix));

    } else {

        dns.resolve(host, (err, records) => {

            if (err) {
                return console.error(err);
            }

            records.forEach((ip) => {
                allowlist.addAddress(ip);
            });

        });

    }
});




setTimeout(async () => {

    console.log("Allowlist", allowlist)
    const host = "192.168.2.1";


    const allow = await new Promise((resolve, reject) => {
        if (ALLOWS.includes(host)) {

            resolve(true);

        } else {

            dns.resolve(host, (err, addresses) => {
                if (err) {

                    reject(err);

                } else {

                    if(addresses.length <= 0){
                        return resolve(false);
                    }

                    resolve(allowlist.check(addresses[0]));

                }
            });

        }
    });


    console.log("Allow:", `${host} = ${allow}`);

}, 100);