qry.js

import { createSocket } from 'dgram'
import { lookup } from 'dns';

const IPRe = /^\d+\.\d+\.\d+\.\d+$/;
const IPPortRe = /^\d+\.\d+\.\d+\.\d+\:\d+$/;

class Qry {
    constructor(options) {
        this.options = Object.assign({
            bindAddress: 1337
        }, options);
        this.socket = createSocket('udp4');
        this.socket.unref();
        this.socket.bind(this.options.bindAddress);
        this.queries = new Map();
        this.socket.on('message', (buffer, rinfo) => {
            const query = this.queries.get(`${rinfo.address}:${rinfo.port}`);
            if(query) query(buffer);
        });
    }
    send(buffer, address, port = 28960) {
        if(typeof buffer === 'string') {
            buffer = new Buffer(buffer, 'binary');
        }
        this.lookup(address)
            .then((sendTo) => {
                return new Promise((resolve) => {
                    const portToSend = sendTo.port || port;
                    this.socket.send(buffer, 0, buffer.length, portToSend, sendTo.address, () => {
                        this.queries.set(`${sendTo.address}:${portToSend}`, resolve);
                    });
                });
            })
    }
    lookup(address) {
        return new Promise((resolve, reject) => {
            if(address.match(IPRe)) {
                resolve({ address});
            } else if(address.match(IPPortRe)) {
                const [address, port] = address.split(':');
                resolve({ address, port });
            } else {
                lookup(host, (address) => {
                    resolve({ address});
                });
            }
        });
    }
}