Support SRV record unfurling for PC networks

lib/util.js

@@ -1,4 +1,5 @@
 var logger = require('./logger');
+var dns = require('dns');
 
 var config = require('../config.json');
 var servers = require('../servers.json');
@@ -148,4 +149,21 @@ exports.getBootTime = function() {
 	}
 
 	return bootTime;
+};
+
+/**
+ * Attempts to resolve Minecraft PC SRV records from DNS, otherwise falling back to the old hostname.
+ *
+ * @param hostname hostname to check
+ * @param port port to pass to callback if required
+ * @param callback function with a hostname and port parameter
+ */
+exports.unfurlSRV = function(hostname, port, callback) {
+	dns.resolveSrv("_minecraft._tcp."+hostname, function (err, records) {
+		if(!records||records.length<=0) {
+			callback(hostname, port);
+			return;
+		}
+		callback(records[0].name, records[0].port);
+	})
 };