ping-mindustry-server.js

const dgram = require('node:dgram')

class CustomBuffer {
	#offset = 0
	#buffer

	/**
	 * @returns {number}
	 */
	get() {
		const data = this.#buffer.readInt8(this.#offset)

		this.#offset += 1

		return data
	}

	/**
	 * @returns {number}
	 */
	getInt4() {
		const data = this.#buffer.readInt32BE(this.#offset)

		this.#offset += 4

		return data
	}

	/**
	 * @param {number} value
	 */
	write(value) {
		this.#buffer.writeInt8(value, this.#offset)

		this.#offset += 1
	}

	/**
	 * @param {Buffer} buffer
	 * @returns {CustomBuffer}
	 */
	static fromBuffer(buffer) {
		const newBuffer = CustomBuffer.alloc(buffer.length)

		newBuffer.copy(buffer)

		return newBuffer
	}

	/**
	 * @param {number} length
	 */
	static alloc(length) {
		const newBuffer = new CustomBuffer()

		newBuffer.#buffer = Buffer.alloc(length)

		return newBuffer
	}

	/**
	 * @param {Buffer} originalBuffer
	 */
	copy(originalBuffer) {
		originalBuffer.copy(this.#buffer, 0)
	}

	/**
	 * @param {BufferEncoding} encoding
	 * @returns {string}
	 */
	toString(encoding = 'utf-8') {
		return this.#buffer.toString(encoding)
	}

	get offset() {
		return this.#offset
	}

	get bufferLeft() {
		return this.#buffer.slice(this.#offset)
	}

	resetOffset() {
		this.#offset = 0
	}
}

class Host {
	ping
	name
	address
	players
	mapname
	wave
	version
	versionType
	playerLimit
	mode
	description
	modeName

	/**
	 *
	 * @param {number} ping
	 * @param {string} name
	 * @param {string} address
	 * @param {string} mapname
	 * @param {number} wave
	 * @param {number} players
	 * @param {number} version
	 * @param {string} versionType
	 * @param {string} mode
	 * @param {number} playerLimit
	 * @param {string} description
	 * @param {string} modeName
	 */
	constructor(
		ping,
		name,
		address,
		mapname,
		wave,
		players,
		version,
		versionType,
		mode,
		playerLimit,
		description,
		modeName
	) {
		this.ping = ping
		this.name = name
		this.address = address
		this.players = players
		this.mapname = mapname
		this.wave = wave
		this.version = version
		this.versionType = versionType
		this.playerLimit = playerLimit
		this.mode = mode
		this.description = description
		this.modeName = modeName
	}
}

/**
 * @param {number} startOffset
 * @param {CustomBuffer} buffer
 * @returns {[number, string]}
 */
const readString = buffer => {
	const length = buffer.get() & 0xff

	const stringBuffer = CustomBuffer.alloc(length)

	for (let i = 0; i < length; i++) {
		const data = buffer.get()

		stringBuffer.write(data)
	}

	return stringBuffer.toString('utf-8')
}

/**
 *
 * @param {[number,number]} hrtime
 * @returns {number}
 */
const parseHrtimeToSeconds = hrtime => {
	return hrtime[0] + hrtime[1] / 1e9
}

/**
 * @param {string} host
 * @param {number} port
 * @param {CustomBuffer} data
 * @param {(error: Error | null, response: CustomBuffer | null) => void} callback
 */
const requestUDP = (host, port, data, callback) => {
	const client = dgram.createSocket('udp4')

	client.on('message', message => {
		client.close()

		const buffer = CustomBuffer.fromBuffer(message)

		callback(null, buffer)
	})

	client.send(data, port, host, err => {
		if (err) callback(err, null)
	})
}

const gamemodes = ['survival', 'sandbox', 'attack', 'pvp', 'editor']

/**
 * @param {string} host
 * @param {number} port
 * @returns {Promise<Host>}
 */
const pingMindustryServer = async (host, port) =>
	new Promise((resolve, reject) => {
		const pingMessage = Buffer.from([-2, 1])

		const startPing = process.hrtime()

		requestUDP(
			mindustryServerHost,
			mindustryServerPort,
			pingMessage,
			(error, response) => {
				if (error) reject(error)

				const pingDuration = process.hrtime(startPing)
				const ping = parseHrtimeToSeconds(pingDuration)

				const name = readString(response)
				const map = readString(response)
				const players = response.getInt4()
				const wave = response.getInt4()
				const version = response.getInt4()
				const verType = readString(response)
				const gamemode = gamemodes[response.get()]
				const limit = response.getInt4()
				const description = readString(response)
				const modeName = readString(response)

				const hostData = new Host(
					ping,
					name,
					`${host}:${port}`,
					map,
					wave,
					players,
					version,
					verType,
					gamemode,
					limit,
					description,
					modeName
				)

				resolve(hostData)
			}
		)
	})

const mindustryServerHost = 'alexmindustryv7.servegame.com'
const mindustryServerPort = 41962

pingMindustryServer(mindustryServerHost, mindustryServerPort)
	.then(console.log)
	.catch(console.error)