Get bedrock server status

udp.status.cjs

/* eslint-disable require-jsdoc */
// @see https://github.com/py-mine/mcstatus/blob/master/mcstatus/bedrock_status.py
const udp = require('dgram');
const port = 48548; // 19000;
const host = 'localhost';

const MAX_WAIT_MS = 2000;
const OFFLINE_MESSAGE_DATA_ID = '00ffff00fefefefefdfdfdfd12345678';
const UNCONNECTED_PING = // see https://wiki.vg/Raknet_Protocol#Unconnected_Ping
    '01' + '0000000000000000' + OFFLINE_MESSAGE_DATA_ID + '0000000000000000'; // fmt: skip;

/**
 * Minecraft Server status abstraction
 */
class Status {
  /**
   * Fetches status from remote UDP host
   * @param {string} host the minecraft server address
   * @param {string|Number} port the minecraft server port
   */
  static async fetch(host, port) {
    console.log('Status.fetch(%s, %s)', host, port);
    const buffer = await UDP.send(host, port, Buffer.from(UNCONNECTED_PING, 'hex'));
    console.log('---------------------------');
    console.log('Parsing...');
    // https://wiki.vg/Raknet_Protocol#Unconnected_Pong
    const packet = {
      type: buffer.slice(0, 1), //    byte
      time: buffer.slice(1, 9), //    long
      guid: buffer.slice(9, 17), //   long
      magic: buffer.slice(17, 33), // magic
      data: buffer.slice(35), //      string
    };
    console.log({packet});
    console.log(packet.data.toString('utf8'));
    const data = packet.data?.toString('utf8')?.split(';') || '';
    const [edition, motd1, protocol, version, count, max, uid, motd2, mode, no, portipv4, portipv6] = data;
    const status = {
      edition, motd1, protocol, version, count, max, uid, motd2, mode, no, portipv4, portipv6,
    };
    console.log({status});
  }
}

/**
 * UDP abstraction
 */
class UDP {
  /**
   * Send a datagram packet and wait for respose.
   * @param {string} host The remote host address
   * @param {string|Number} port The port to connect to
   * @param {string|Buffer} message The message to send
   * @return {Buffer} The returned udp message
   */
  static async send(host, port, message) {
    const buffer = Buffer.from(message);
    console.log(`Sending '${buffer.toString('hex')}' to ${host}:${port}`);
    return new Promise((resolve, reject) => {
      const client = udp.createSocket('udp4');
      const timeout = setTimeout(() => onError(new Error('UDP: Timeout. No response.')), MAX_WAIT_MS);
      client.on('error', onError);
      client.send(buffer, port, host, onError);
      client.on('message', (msg, info) => {
        console.log('---------------------------');
        console.log('Received %d bytes from %s:%d', msg.length, info.address, info.port);
        console.log(`-->${msg.toString('hex')}`);
        console.log(`-->${msg.toString('utf8')}`);
        client.close();
        clearTimeout(timeout);
        resolve(msg);
      });
      // eslint-disable-next-line require-jsdoc
      function onError(e) {
        if (e) {
          console.error('UPD Error: ' + e);
          client.close();
          clearTimeout(timeout);
          reject(e);
        }
      }
    });
  }
}

// Go
Status.fetch(host, port);