✨ feat: Host a relay on Hetzner (#114)

We are hosting a [MoQ](https://quic.video) relay on a remote (bare
metal) server on Hetzner

With a lot of help from @victorpahuus

packages/moq/transport/connection.ts

@@ -0,0 +1,95 @@
+import * as Control from "./control"
+import { Objects } from "./objects"
+import { asError } from "../common/error"
+
+import { Publisher } from "./publisher"
+import { Subscriber } from "./subscriber"
+
+export class Connection {
+	// The established WebTransport session.
+	#quic: WebTransport
+
+	// Use to receive/send control messages.
+	#control: Control.Stream
+
+	// Use to receive/send objects.
+	#objects: Objects
+
+	// Module for contributing tracks.
+	#publisher: Publisher
+
+	// Module for distributing tracks.
+	#subscriber: Subscriber
+
+	// Async work running in the background
+	#running: Promise<void>
+
+	constructor(quic: WebTransport, control: Control.Stream, objects: Objects) {
+		this.#quic = quic
+		this.#control = control
+		this.#objects = objects
+
+		this.#publisher = new Publisher(this.#control, this.#objects)
+		this.#subscriber = new Subscriber(this.#control, this.#objects)
+
+		this.#running = this.#run()
+	}
+
+	close(code = 0, reason = "") {
+		this.#quic.close({ closeCode: code, reason })
+	}
+
+	async #run(): Promise<void> {
+		await Promise.all([this.#runControl(), this.#runObjects()])
+	}
+
+	announce(namespace: string) {
+		return this.#publisher.announce(namespace)
+	}
+
+	announced() {
+		return this.#subscriber.announced()
+	}
+
+	subscribe(namespace: string, track: string) {
+		return this.#subscriber.subscribe(namespace, track)
+	}
+
+	subscribed() {
+		return this.#publisher.subscribed()
+	}
+
+	async #runControl() {
+		// Receive messages until the connection is closed.
+		for (;;) {
+			const msg = await this.#control.recv()
+			await this.#recv(msg)
+		}
+	}
+
+	async #runObjects() {
+		for (;;) {
+			const obj = await this.#objects.recv()
+			if (!obj) break
+
+			await this.#subscriber.recvObject(obj)
+		}
+	}
+
+	async #recv(msg: Control.Message) {
+		if (Control.isPublisher(msg)) {
+			await this.#subscriber.recv(msg)
+		} else {
+			await this.#publisher.recv(msg)
+		}
+	}
+
+	async closed(): Promise<Error> {
+		try {
+			await this.#running
+			return new Error("closed")
+		} catch (e) {
+			return asError(e)
+		}
+	}
+}