node-gamedig/lib/GlobalUdpSocket.js

import { createSocket } from "dgram";
import { debugDump } from "./HexUtil.js";
import { promisify } from "util";
import Logger from "./Logger.js";

export default class GlobalUdpSocket {
    constructor({port}) {
        this.socket = null;
        this.callbacks = new Set();
        this.debuggingCallbacks = new Set();
        this.logger = new Logger();
        this.port = port;
    }

    async _getSocket() {
        if (!this.socket) {
            const udpSocket = createSocket({
                type: 'udp4',
                reuseAddr: true
            });
            udpSocket.unref();
            udpSocket.on('message', (buffer, rinfo) => {
                const fromAddress = rinfo.address;
                const fromPort = rinfo.port;
                this.logger.debug(log => {
                    log(fromAddress + ':' + fromPort + " <--UDP(" + this.port + ")");
                    log(debugDump(buffer));
                });
                for (const callback of this.callbacks) {
                    callback(fromAddress, fromPort, buffer);
                }
            });
            udpSocket.on('error', e => {
                this.logger.debug("UDP ERROR:", e);
            });
            await promisify(udpSocket.bind).bind(udpSocket)(this.port);
            this.port = udpSocket.address().port;
            this.socket = udpSocket;
        }
        return this.socket;
    }

    async send(buffer, address, port, debug) {
        const socket = await this._getSocket();

        if (debug) {
            this.logger._print(log => {
                log(address + ':' + port + " UDP(" + this.port + ")-->");
                log(debugDump(buffer));
            });
        }

        await promisify(socket.send).bind(socket)(buffer,0,buffer.length,port,address);
    }

    addCallback(callback, debug) {
        this.callbacks.add(callback);
        if (debug) {
            this.debuggingCallbacks.add(callback);
            this.logger.debugEnabled = true;
        }
    }
    removeCallback(callback) {
        this.callbacks.delete(callback);
        this.debuggingCallbacks.delete(callback);
        this.logger.debugEnabled = this.debuggingCallbacks.size > 0;
    }
}