Class MDNS

modules/network/mdns/mdns.js:39–574

const TTL = 4500;

class MDNS extends Socket {
	constructor(dictionary = {}, callback) {
		super({kind: "UDP", port: MDNS.PORT, multicast: MDNS.IP});

		this.services = [];
		this.monitors = [];
		this.client = callback ?? function() {};

		if (dictionary.hostName) {
			this.hostName = dictionary.hostName;
			this.hostNameLower = this.hostName.toLowerCase();
			this.probing = 1;
			Timer.set(() => this.probe(), 0);
		}
	}
	close() {
		while (this.services.length)
			this.remove(this.services[0]);

		while (this.monitors.length)
			this.remove(this.monitors[0].service.substring(0, this.monitors[0].service.length - 6));

		Timer.clear(this.probeTimer);

		super.close();
	}
	add(service) {
		if (!this.hostName)
			throw new Error("no hostName");

		if (this.probing)
			throw new Error("not ready");

		service.txt ??= {};
		this.services.push(service);

		this.write(MDNS.IP, MDNS.PORT, this.reply(null, 0x1F | 0x8000, service, true));		// remove before adding to clear stale state in clients
		service.timer = Timer.repeat(timer => {
			this.write(MDNS.IP, MDNS.PORT, this.reply(null, 0x1F, service));
			timer.interval *= 2;
			if (timer.interval > 16000) {
				Timer.clear(timer);
				delete service.timer;
			}
			else
				Timer.schedule(timer, timer.interval, timer.interval);
		}, 500);
		service.timer.interval = 500;
	}
	update(service) {
		const index = this.services.indexOf(service);
		if (index < 0) throw new Error("service not found");

		if (!service.updater) {
			service.updater = Timer.set(updater => {
				this.write(MDNS.IP, MDNS.PORT, this.reply(null, 0x04 | 0x8000, service));
				updater.interval += 250;
				if (updater.interval >= 1500) {