matchmaker.js

// Copyright Epic Games, Inc. All Rights Reserved.

//Start : AWS - expose matchmaker only as api endpoint
var enableRedirectionLinks = false;
//End : AWS - expose matchmaker only as api endpoint
var enableRESTAPI = true;

const defaultConfig = {
	// The port clients connect to the matchmaking service over HTTP
	HttpPort: 80,
	UseHTTPS: false,
	// The matchmaking port the signaling service connects to the matchmaker
	MatchmakerPort: 9999,

	// Log to file
	LogToFile: true
};

// Similar to the Signaling Server (SS) code, load in a config.json file for the MM parameters
const argv = require('yargs').argv;

var configFile = (typeof argv.configFile != 'undefined') ? argv.configFile.toString() : 'config.json';
console.log(`configFile ${configFile}`);
const config = require('./modules/config.js').init(configFile, defaultConfig);
console.log("Config: " + JSON.stringify(config, null, '\t'));

const express = require('express');
var cors = require('cors');
const app = express();
const http = require('http').Server(app);
const fs = require('fs');
const path = require('path');
const logging = require('./modules/logging.js');
//Start : AWS - Loaded aws sdk for iterfacing with dynamoDB and SSM paramater store
var AWS = require('aws-sdk');
const { SSMClient, GetParameterCommand } = require("@aws-sdk/client-ssm");
// please change based on region
AWS.config.update({region: config.AWSRegion});
var ddb = new AWS.DynamoDB({ apiVersion: "2012-08-10" });
//End : AWS - Loaded aws sdk for iterfacing with dynamoDB and SSM paramater store

logging.RegisterConsoleLogger();

if (config.LogToFile) {
	logging.RegisterFileLogger('./logs');
}

// A list of all the Cirrus server which are connected to the Matchmaker.
var cirrusServers = new Map();
var theSSMSecret=''
//
// Parse command line.
//

if (typeof argv.HttpPort != 'undefined') {
	config.HttpPort = argv.HttpPort;
}
if (typeof argv.MatchmakerPort != 'undefined') {
	config.MatchmakerPort = argv.MatchmakerPort;
}

http.listen(config.HttpPort, () => {
    console.log('HTTP listening on *:' + config.HttpPort);
});


if (config.UseHTTPS) {
	//HTTPS certificate details
	const options = {
		key: fs.readFileSync(path.join(__dirname, './certificates/client-key.pem')),
		cert: fs.readFileSync(path.join(__dirname, './certificates/client-cert.pem'))
	};

	var https = require('https').Server(options, app);

	//Setup http -> https redirect
	console.log('Redirecting http->https');
	app.use(function (req, res, next) {
		if (!req.secure) {
			if (req.get('Host')) {
				var hostAddressParts = req.get('Host').split(':');
				var hostAddress = hostAddressParts[0];
				if (httpsPort != 443) {
					hostAddress = `${hostAddress}:${httpsPort}`;
				}
				return res.redirect(['https://', hostAddress, req.originalUrl].join(''));
			} else {
				console.error(`unable to get host name from header. Requestor ${req.ip}, url path: '${req.originalUrl}', available headers ${JSON.stringify(req.headers)}`);
				return res.status(400).send('Bad Request');
			}
		}
		next();
	});

	https.listen(443, function () {
		console.log('Https listening on 443');
	});
}




// No servers are available so send some simple JavaScript to the client to make
// it retry after a short period of time.
function sendRetryResponse(res) {
	res.send(`All ${cirrusServers.size} Cirrus servers are in use. Retrying in <span id="countdown">3</span> seconds.
	<script>
		var countdown = document.getElementById("countdown").textContent;
		setInterval(function() {
			countdown--;
			if (countdown == 0) {
				window.location.reload(1);
			} else {
				document.getElementById("countdown").textContent = countdown;
			}
		}, 1000);
	</script>`);
}

// Get a Cirrus server if there is one available which has no clients connected.
function getAvailableCirrusServer() {
	for (cirrusServer of cirrusServers.values()) {
		if (cirrusServer.numConnectedClients === 0 && cirrusServer.ready === true) {

			// Check if we had at least 10 seconds since the last redirect, avoiding the 
			// chance of redirecting 2+ users to the same SS before they click Play.
			// In other words, give the user 10 seconds to click play button the claim the server.
			if( cirrusServer.hasOwnProperty('lastRedirect')) {
				if( ((Date.now() - cirrusServer.lastRedirect) / 1000) < 10 )
					continue;
			}
			cirrusServer.lastRedirect = Date.now();

			return cirrusServer;
		}
	}
	
	console.log('WARNING: No empty Cirrus servers are available');
	return undefined;
}
//Start : AWS - get client secret for validation from parameter store
const getParameterInfo = async () => { 
	const client = new SSMClient({ region: "ap-south-1" });
	const input = { // GetParameterRequest
		Name: "matchmakerclientsecret" // required
	};
	const paramSSMcommand = new GetParameterCommand(input);
	const paramSSMresponse= await client.send(paramSSMcommand);
	theSSMSecret=paramSSMresponse.Parameter.Value
}
//End : AWS - get client secret for validation from parameter store

//Start : AWS -  Get Query String from DynamoDB for Signalling Instance
const getQueryStringFromDDB = async (instanceId) => {     
    	var qs=''
    	console.log(instanceId)
        var params = {
        	FilterExpression: "InstanceID = :t",
			ExpressionAttributeValues: {
    			":t": {S: instanceId}
			},
			ProjectionExpression: "QueryString",
            TableName: "instanceMapping"
        };
        
        const data =await ddb.scan(params).promise()
    	qs=data.Items[0].QueryString.S
		console.log("Success", qs);
		return qs
}
//End : AWS -  Get Query String from DynamoDB for Signalling Instance

if(enableRESTAPI) {
	// Handle REST signalling server only request.
	app.options('/signallingserver', cors())
	app.get('/signallingserver', cors(),  async(req, res) => {
		//Start : AWS - check if a valid secret was provided in header to authenticate calls
		console.log(config.AWSRegion)
		await getParameterInfo()
		if(req.header("clientsecret") != undefined && req.header("clientsecret")==theSSMSecret)
		{
			cirrusServer = getAvailableCirrusServer();
			if (cirrusServer != undefined) {
				var qs=await getQueryStringFromDDB(cirrusServer.instanceID);
				console.log("Received", qs);
				// The original function used to send the instance ip/port to allow connection to Signalling
				// We have modified the logic to send a query string which allows to connect to Signalling
				// via an external load balancer. The query string is in dynamoDB
				res.json({ signallingServer: qs});
				console.log(`Returning ${cirrusServer.address}:${cirrusServer.port}`);
			} else {
				res.status(400).send('No signalling servers available');
			}
		}else
		{
			res.status(401).send('Unauthorized');
		}
		//End : AWS - check if a valid secret was provided in header to authenticate calls
	});
}

if(enableRedirectionLinks) {
	// Handle standard URL.
	app.get('/', (req, res) => {
		cirrusServer = getAvailableCirrusServer();
		if (cirrusServer != undefined) {
			res.redirect(`http://${cirrusServer.address}:${cirrusServer.port}/`);
			//console.log(req);
			console.log(`Redirect to ${cirrusServer.address}:${cirrusServer.port}`);
		} else {
			sendRetryResponse(res);
		}
	});

	// Handle URL with custom HTML.
	app.get('/custom_html/:htmlFilename', (req, res) => {
		cirrusServer = getAvailableCirrusServer();
		if (cirrusServer != undefined) {
			res.redirect(`http://${cirrusServer.address}:${cirrusServer.port}/custom_html/${req.params.htmlFilename}`);
			console.log(`Redirect to ${cirrusServer.address}:${cirrusServer.port}`);
		} else {
			sendRetryResponse(res);
		}
	});
}

//
// Connection to Cirrus.
//

const net = require('net');

function disconnect(connection) {
	console.log(`Ending connection to remote address ${connection.remoteAddress}`);
	connection.end();
}

const matchmaker = net.createServer((connection) => {
	connection.on('data', (data) => {
		try {
			message = JSON.parse(data);

			if(message)
				console.log(`Message TYPE: ${message.type}`);
		} catch(e) {
			console.log(`ERROR (${e.toString()}): Failed to parse Cirrus information from data: ${data.toString()}`);
			disconnect(connection);
			return;
		}
		if (message.type === 'connect') {
			// A Cirrus server connects to this Matchmaker server.
			cirrusServer = {
				address: message.address,
				port: message.port,
				numConnectedClients: 0,
				lastPingReceived: Date.now(),
				instanceID:message.instanceId
			};
			cirrusServer.ready = message.ready === true;

			// Handles disconnects between MM and SS to not add dupes with numConnectedClients = 0 and redirect users to same SS
			// Check if player is connected and doing a reconnect. message.playerConnected is a new variable sent from the SS to
			// help track whether or not a player is already connected when a 'connect' message is sent (i.e., reconnect).
			if(message.playerConnected == true) {
				cirrusServer.numConnectedClients = 1;
			}

			// Find if we already have a ciruss server address connected to (possibly a reconnect happening)
			let server = [...cirrusServers.entries()].find(([key, val]) => val.address === cirrusServer.address && val.port === cirrusServer.port);

			// if a duplicate server with the same address isn't found -- add it to the map as an available server to send users to.
			if (!server || server.size <= 0) {
				console.log(`Adding connection for ${cirrusServer.address.split(".")[0]} with playerConnected: ${message.playerConnected}`)
				cirrusServers.set(connection, cirrusServer);
            } else {
				console.log(`RECONNECT: cirrus server address ${cirrusServer.address.split(".")[0]} already found--replacing. playerConnected: ${message.playerConnected}`)
				var foundServer = cirrusServers.get(server[0]);
				
				// Make sure to retain the numConnectedClients from the last one before the reconnect to MM
				if (foundServer) {					
					cirrusServers.set(connection, cirrusServer);
					console.log(`Replacing server with original with numConn: ${cirrusServer.numConnectedClients}`);
					cirrusServers.delete(server[0]);
				} else {
					cirrusServers.set(connection, cirrusServer);
					console.log("Connection not found in Map() -- adding a new one");
				}
			}
		} else if (message.type === 'streamerConnected') {
			// The stream connects to a Cirrus server and so is ready to be used
			cirrusServer = cirrusServers.get(connection);
			if(cirrusServer) {
				cirrusServer.ready = true;
				console.log(`Cirrus server ${cirrusServer.address}:${cirrusServer.port} ready for use`);
			} else {
				disconnect(connection);
			}
		} else if (message.type === 'streamerDisconnected') {
			// The stream connects to a Cirrus server and so is ready to be used
			cirrusServer = cirrusServers.get(connection);
			if(cirrusServer) {
				cirrusServer.ready = false;
				console.log(`Cirrus server ${cirrusServer.address}:${cirrusServer.port} no longer ready for use`);
			} else {
				disconnect(connection);
			}
		} else if (message.type === 'clientConnected') {
			// A client connects to a Cirrus server.
			cirrusServer = cirrusServers.get(connection);
			if(cirrusServer) {
				cirrusServer.numConnectedClients++;
				console.log(`Client connected to Cirrus server ${cirrusServer.address}:${cirrusServer.port}`);
			} else {
				disconnect(connection);
			}
		} else if (message.type === 'clientDisconnected') {
			// A client disconnects from a Cirrus server.
			cirrusServer = cirrusServers.get(connection);
			if(cirrusServer) {
				cirrusServer.numConnectedClients--;
				console.log(`Client disconnected from Cirrus server ${cirrusServer.address}:${cirrusServer.port}`);
				if(cirrusServer.numConnectedClients === 0) {
					// this make this server immediately available for a new client
					cirrusServer.lastRedirect = 0;
				}
			} else {				
				disconnect(connection);
			}
		} else if (message.type === 'ping') {
			cirrusServer = cirrusServers.get(connection);
			if(cirrusServer) {
				cirrusServer.lastPingReceived = Date.now();
			} else {				
				disconnect(connection);
			}
		} else {
			console.log('ERROR: Unknown data: ' + JSON.stringify(message));
			disconnect(connection);
		}
	});

	// A Cirrus server disconnects from this Matchmaker server.
	connection.on('error', () => {
		cirrusServer = cirrusServers.get(connection);
		if(cirrusServer) {
			cirrusServers.delete(connection);
			console.log(`Cirrus server ${cirrusServer.address}:${cirrusServer.port} disconnected from Matchmaker`);
		} else {
			console.log(`Disconnected machine that wasn't a registered cirrus server, remote address: ${connection.remoteAddress}`);
		}
	});
});

matchmaker.listen(config.MatchmakerPort, () => {
	console.log('Matchmaker listening on *:' + config.MatchmakerPort);
});