refactor: major code cleanups :-)

first working version

src/server/UDPServer.ts

@@ -0,0 +1,80 @@
+import * as dgram from 'dgram';
+import { SocketType } from 'dgram';
+import * as events from 'events';
+import { EventEmitter } from 'events';
+import { newDeferredPromise } from '../helpers';
+import { IServer } from '../types/Server';
+
+export class UDPServer extends events.EventEmitter implements IServer {
+	static MAX_RETRIES = 3;
+
+	private timeout: { [key: string]: NodeJS.Timeout } = {};
+
+	private server: dgram.Socket;
+
+	constructor(private port: number, type: SocketType = 'udp4') {
+		super();
+		this.server = dgram.createSocket(type);
+	}
+
+	sendToClient(
+		msg: string | Uint8Array,
+		port?: number,
+		address?: string,
+		callback?: (error: Error | null, bytes: number) => void,
+		expectAcknowledgment = true
+	): void {
+		let retried = 0;
+
+		const sendResponse = (): void => {
+			if (retried > 0) {
+				console.warn(
+					`no confirmation of last message from ${address}:${port}, re-sending response... (bytes: ${msg.length}, try: ${retried}/${UDPServer.MAX_RETRIES})`
+				);
+			}
+
+			// send message to client
+			this.server.send(msg, 0, msg.length, port, address, callback);
+
+			// retry up to MAX_RETRIES to send this message,
+			// we automatically retry if there is no confirmation (=any incoming message from client)
+			// if expectAcknowledgment (e.g. Access-Accept or Access-Reject) is set, we do not retry
+			const identifierForRetry = `${address}:${port}`;
+			if (expectAcknowledgment && retried < UDPServer.MAX_RETRIES) {
+				this.timeout[identifierForRetry] = setTimeout(sendResponse, 600 * (retried + 1));
+			}
+			retried += 1;
+		};
+
+		sendResponse();
+	}
+
+	async start(): Promise<EventEmitter> {
+		const startServer = newDeferredPromise();
+		this.server.on('listening', () => {
+			const address = this.server.address();
+			console.log(`radius server listening ${address.address}:${address.port}`);
+
+			this.setupListeners();
+			startServer.resolve();
+		});
+
+		this.server.on('message', (_msg, rinfo) => {
+			console.log('incoming message 2');
+
+			// message retrieved, reset timeout handler
+			const identifierForRetry = `${rinfo.address}:${rinfo.port}`;
+			if (this.timeout[identifierForRetry]) {
+				clearTimeout(this.timeout[identifierForRetry]);
+			}
+		});
+
+		this.server.bind(this.port);
+
+		return startServer.promise;
+	}
+
+	private setupListeners() {
+		this.server.on('message', (message, rinfo) => this.emit('message', message, rinfo));
+	}
+}