GoodWe UDP Caching Proxy Server

const dgram = require('dgram');
const server = dgram.createSocket('udp4');

const INVERTER_HOST = 'goodwe';
const TIMEOUT_BY_REQUEST = {
    'f70388b800213ac1' : 60000, // inverter info
};
const DEFAULT_TIMEOUT = 5000;

const cacheByRequest = new Map();

server.on('error', (err) => {
    console.error(err);
    server.close();
});

server.on('message', (msg, rinfo) => {
    const hex = msg.toString('hex');
    console.log(`Server got request (HEX): ${hex}`);

    const reply = (msg) => {
        server.send(msg, rinfo.port, rinfo.address);
    };

    if (cacheByRequest.has(hex) && cacheByRequest.get(hex).timeout > Date.now()) {
        reply(cacheByRequest.get(hex).data);
    }else {
        const client = dgram.createSocket('udp4');
        client.on('message', (msg) => {
            cacheByRequest.set(hex, {
                timeout: Date.now() + (TIMEOUT_BY_REQUEST[hex] || DEFAULT_TIMEOUT),
                data: msg,
            });
            reply(msg);
            client.close();
        });
        client.send(msg, 0, msg.length, 8899, INVERTER_HOST);
    }
});

server.bind(8899);