mcping.js

'use strict';

const net = require('net');
const dgram = require('dgram');
const process = require('process');

// FE01FA ping compatible with 1.4.4, 1.5.2, 1.6.4(*), 1.7.10, 1.8.9, 1.9
// (*) MC|PingHost is required for 1.6.4, or it'll take ~2 seconds to get a reply
// (*) MC|PingHost is not compatible with 1.3.2 and earlier (java.io.IOException: Received string length longer than maximum allowed (19712 > 16)), for that see ping_fe
function ping_fe01fa(options, cb) {
  _ping_buffer(options, cb, new Buffer('fe01'+
        'fa'+ // plugin message
        '000b'+'004D0043007C00500069006E00670048006F00730074'+ // MC|PingHost,
        '0007'+ // 7+len(hostname)
        '4a'+   // protocol version (74, last)
        '0000'+''+ // hostname TODO
        '00000000' // port TODO
        ,'hex'),
      'fe01fa');
}

// FE01 compatible with 1.3.2 and 1.2.5 (unlike FE01FA), but slow on 1.6.4, although its fast on 1.4.4, 1.5.2, and 1.7.10+
function ping_fe01(options, cb) {
  _ping_buffer(options, cb, new Buffer('fe01', 'hex'), 'fe01');
}

// plain FE pings work on 1.3.2, and so do fe01, but not fe01fa + MC|PingHost (used in ping_fe01fa)
function ping_fe(options, cb) {
  _ping_buffer(options, cb, new Buffer('fe', 'hex'), 'fe');
}

// the 2011 beta 1.9 query protocol from https://dinnerbone.com/blog/2011/10/14/minecraft-19-has-rcon-and-query
function ping_fefd_udp(options, cb) {
  const host = options.host;
  const port = options.port;
  const udp = dgram.createSocket('udp4');

  //console.log('udp ping');

  const STARTED = 0;
  const SENT_CHALLENGE_REQUEST = 1;
  const SENT_STATUS_REQUEST = 2;
  const DONE = 3;
  let state = 0;

  udp.on('error', (err) => {
    //console.log(`udp error:\n${err.stack}`);
    cb(err, null, 'fefd_udp');
    udp.close();
  });

  udp.on('message', (msg, rinfo) => {
    //console.log(msg);
    //console.log(`udp got: ${msg} from ${rinfo.address}:${rinfo.port}`);
    if (state === STARTED) {
      cb(new Error('received unexpected packet before sent anything'), null, 'fefd_udp');
      return;
    } else if (state === SENT_CHALLENGE_REQUEST) {
      // challenge token
      // 09          challenge type
      // 00 00 00 00 id token (sent all zeros)
      // xx xx xx xx new challenge token
      if (msg[0] != 0x09) {
        cb(new Error('unexpected packet received after sent challenge request'), null, 'fefd_udp');
        return;
      }
      // challenge token is received as ASCII decimal string, but replied as encoded uint32be
      const challengeTokenString = msg.slice(5).toString();
      const challengeTokenInt = parseInt(challengeTokenString);
      //console.log('challenge token: '+challengeTokenInt);
      const challengeTokenBuffer = new Buffer(4);
      challengeTokenBuffer.writeUInt32BE(challengeTokenInt);

      const statusRequest = new Buffer(
        'fefd'+ // magic
        '00'+   // status type
        '00000000'+ // id token
        challengeTokenBuffer.toString('hex')+ // challenge token
        '00000000', // id token, again (extended status request) (see https://github.com/Dinnerbone/mcstatus/commit/6b6a5659156785bcaaa75980782215f777bd5b97 it gets more)
        'hex');

      //console.log('requesting status');
      //console.log(statusRequest.toString('hex'));
      udp.send(statusRequest, 0, statusRequest.length, port, host, function() {
        state = SENT_STATUS_REQUEST;
      });
    } else if (state === SENT_STATUS_REQUEST) {
      //console.log('response', msg);
      //console.log('response', msg.toString('hex'));
      //console.log('response', msg.toString());
      const array = msg.toString('binary').split('\0');
      //console.log(array);
      let result = {};
      // example response array, some fields are not fixed strings
      // ['', '', '', '', '', 'splitnum', '\x80', 'hostname', 'A Minecraft Server', 'gametype', 'SMP', 'game_id', 'MINECRAFT', 'version', '1.5.2', 'plugins', 'CraftBukkit on Bukkit 1.5.2-R1.1-SNAPSHOT: MultiWorld 4.5.4; SilkSpawners 3.2.2; OpenInv 2.0.2; EnchantMore 2.0; WorldEdit 5.5.6', 'map', 'world', 'numplayers', '0', 'maxplayers', '20', 'hostport', '25565', 'hostip', '0.0.0.0', '', '\x01player_', '', '', '']
      result.worldHeight = array[6].charCodeAt(0);
      result.motd = array[8];
      result.gameType = array[10];
      result.gameName = array[12];
      result.gameVersion = array[14];
      result.plugins = array[16]; // TODO: decode structure, which is:  server-software: plugin1; plugin2; plugin3...
      result.defaultWorld = array[18];
      result.numPlayers = parseInt(array[20]);
      result.maxPlayers = parseInt(array[22]);
      result.port = parseInt(array[24]);
      result.host = array[26];
      // TODO: online players comes last, parse it
      //console.log('result',result);
      state = DONE;
      cb(null, result, 'fefd_udp');
    }
  });

  udp.on('listening', () => {
    const address = udp.address();
    //console.log(`udp listening ${address.address}:${address.port}`);

    // query request
    const request = new Buffer('fefd090000000000000000', 'hex');
    udp.send(request, 0, request.length, port, host, function() {
      state = SENT_CHALLENGE_REQUEST;
    });
  });

  udp.bind();
}

function _ping_buffer(options, cb, buffer, type) {
  const host = options.host;
  const port = options.port;
  const socket = net.connect(port, host);
  let calledCB = false;
  socket.on('connect', () => {
    //console.log('connected');
    socket.write(buffer);
  });
  socket.on('end', () => {
    //console.log('ended',type);
    if (!calledCB) {
      cb(new Error('server unexpectedly closed connection'), null, type);
      calledCB = true;
    }
  });
  socket.on('error', (err) => {
    cb(err, null, type);
    calledCB = true;
  });
  socket.on('data', (raw) => {
    //console.log('data(fe01fa)',raw);
    const packetID = raw.readUInt8(0);
    if (packetID !== 0xff) {
      socket.end();
      cb(new Error('unexpected packet id'), null, type);
      calledCB = true;
      return;
    }
    const length = raw.slice(1).readUInt16BE(); // in UCS-2/UTF-16 characters

    const string = raw.slice(4).toString('ucs2');
    //console.log('response string',string);
    let result = {};

    if (string[0] == '\xa7') {
      // https://gist.github.com/Jckf/4574114#file-minecraftserver-java-L170
      const parts = string.split('\0');
      //console.log(parts);
      result.pingVersion = parseInt(parts[0].slice(1));
      result.protocolVersion = parseInt(parts[1]);
      result.gameVersion = parts[2];
      result.motd = parts[3];
      result.playersOnline = parseInt(parts[4]);
      result.maxPlayers = parseInt(parts[5]);
    } else {
      const parts = string.split('\xa7');
      if (parts.length !== 3) {
        socket.end();
        cb(new Error('unexpected ping type response, started with 0xff but not followed by 0xa7 or 3 x 0xa7 parts'), null, type);
        calledCB = true;
        return;
      }
      result.pingVersion = 0;
      result.motd = parts[0];
      result.playersOnline = parseInt(parts[1]);
      result.maxPlayers = parseInt(parts[2]);
    }
    //console.log('result',result);
    socket.end();
    cb(null, result, type);
    calledCB = true;
  });
}

function ping_all(options, cb) {
  ping_fefd_udp(options, cb);
  ping_fe01fa(options, cb);
  ping_fe01(options, cb);
  ping_fe(options, cb);
}

module.exports = {
  ping_fefd_udp,
  ping_fe01fa,
  ping_fe01,
  ping_fe,

  ping_all,
  ping: ping_fe01fa
};