Show supported versions for PC servers

The Minetrack daemon will send a different protocol version each time
it pings a server. If a server responds with the same protocol version,
it is assumed that the version is supported, and it is shown on the
page above the server's player count.

The list of versions to be tried is stored in config.json.
At the moment, 4 versions are checked:
- 4 (Minecraft 1.7.2)
- 5 (Minecraft 1.7.10)
- 47 (Minecraft 1.8)
- 107 (Minecraft 1.9)

app.js

@@ -11,6 +11,12 @@ var servers = require('./servers.json');
 var networkHistory = [];
 var connectedClients = 0;
 
+var currentVersionIndex = {
+	'PC': 0,
+	'PE': 0
+};
+var networkVersions = [];
+
 var graphData = [];
 var lastGraphPush = [];
 
@@ -18,6 +24,7 @@ function pingAll() {
 	for (var i = 0; i < servers.length; i++) {
 		// Make sure we lock our scope.
 		(function(network) {
+			var attemptedVersion = config.versions[network.type][currentVersionIndex[network.type]];
 			ping.ping(network.ip, network.port, network.type, config.rates.connectTimeout, function(err, res) {
 				// Handle our ping results, if it succeeded.
 				if (err) {
@@ -29,20 +36,62 @@ function pingAll() {
 					res.favicon = config.faviconOverride[network.name];
 				}
 
-				handlePing(network, res, err);
-			});
+				handlePing(network, res, err, attemptedVersion);
+			}, attemptedVersion);
 		})(servers[i]);
 	}
+
+	currentVersionIndex['PC']++;
+	currentVersionIndex['PE']++;
+
+	if (currentVersionIndex['PC'] >= config.versions['PC'].length) {
+		// Loop around
+		currentVersionIndex['PC'] = 0;
+	}
+
+	if (currentVersionIndex['PE'] >= config.versions['PE'].length) {
+		// Loop around
+		currentVersionIndex['PE'] = 0;
+	}
 }
 
 // This is where the result of a ping is feed.
 // This stores it and converts it to ship to the frontend.
-function handlePing(network, res, err) {
+function handlePing(network, res, err, attemptedVersion) {
+	// Log our response.
+	if (!networkHistory[network.name]) {
+		networkHistory[network.name] = [];
+	}
+
+	// Update the version list
+	if (!networkVersions[network.name]) {
+		networkVersions[network.name] = [];
+	}
+
+	// If the result version matches the attempted version, the version is supported
+	var _networkVersions = networkVersions[network.name];
+	if (res) {
+		if (res.version == attemptedVersion) {
+			if (_networkVersions.indexOf(res.version) == -1) {
+				_networkVersions.push(res.version);
+			}
+		} else {
+			// Mismatch, so remove the version from the supported version list
+			var index = _networkVersions.indexOf(attemptedVersion);
+			if (index != -1) {
+				_networkVersions.splice(index, 1);
+			}
+		}
+	}
+
+	// Update the clients
 	var networkSnapshot = {
 		info: {
 			name: network.name,
-			timestamp: util.getCurrentTimeMs()
-		}
+			timestamp: util.getCurrentTimeMs(),
+			type: network.type
+		},
+		versions: _networkVersions
 	};
 
 	if (res) {
@@ -53,11 +102,6 @@ function handlePing(network, res, err) {
 
 	server.io.sockets.emit('update', networkSnapshot);
 
-	// Log our response.
-	if (!networkHistory[network.name]) {
-		networkHistory[network.name] = [];
-	}
-
 	var _networkHistory = networkHistory[network.name];
 
 	// Remove our previous data that we don't need anymore.
@@ -72,12 +116,13 @@ function handlePing(network, res, err) {
 	_networkHistory.push({
 		error: err,
 		result: res,
+		versions: _networkVersions,
 		timestamp: util.getCurrentTimeMs(),
         info: {
             ip: network.ip,
             port: network.port,
             type: network.type,
-            name: network.name
+            name: network.name,
         }
 	});
 
@@ -217,4 +262,4 @@ if (config.logToDatabase) {
 	logger.log('warn', 'Database logging is not enabled. You can enable it by setting "logToDatabase" to true in config.json. This requires sqlite3 to be installed.');
 
 	startServices();
-}
+}