2 files changed, 43 insertions, 2 deletions

diff --git a/src/server/Main.hx b/src/server/Main.hx
index 8a5f381..07f782a 100644
--- a/src/server/Main.hx
+++ b/src/server/Main.hx
@@ -31,10 +31,10 @@ class Main {
 	public final logsDir:String;
 	final verbose:Bool;
 	final statePath:String;
-	final wss:WSServer;
+	var wss:WSServer;
 	final localIp:String;
 	var globalIp:String;
-	final port:Int;
+	var port:Int;
 	public final config:Config;
 	final userList:UserList;
 	final clients:Array<Client> = [];
@@ -85,6 +85,23 @@ class Main {
 		final envPort = (process.env : Dynamic).PORT;
 		if (envPort != null) port = envPort;
 
+		var attempts = 5;
+		function preparePort():Void {
+			Utils.isPortFree(port, free -> {
+				if (!free && attempts > 0) {
+					trace('Warning: port $port is already in use. Changed to ${port + 1}');
+					attempts--;
+					port++;
+					preparePort();
+					return;
+				}
+				runServer();
+			});
+		}
+		preparePort();
+	}
+
+	function runServer():Void {
 		trace('Local: http://$localIp:$port');
 		Utils.getGlobalIp(ip -> {
 			globalIp = ip;
diff --git a/src/server/Utils.hx b/src/server/Utils.hx
index 4e2fc9d..bab6300 100644
--- a/src/server/Utils.hx
+++ b/src/server/Utils.hx
@@ -2,6 +2,7 @@ package server;
 
 import js.node.url.URL;
 import js.node.Https;
+import js.node.Http;
 import js.node.Os;
 import sys.FileSystem;
 
@@ -11,6 +12,29 @@ class Utils {
 		if (!FileSystem.exists(path)) FileSystem.createDirectory(path);
 	}
 
+	public static function isPortFree(port:Int, callback:(free:Bool)->Void):Void {
+		final server = Http.createServer();
+		final timeout = 1000;
+		var status = false;
+
+		server.setTimeout(timeout);
+		server.once("error", function(err) {
+			status = false;
+			server.close();
+		});
+		server.once("timeout", function () {
+			status = false;
+			trace('Timeout (${timeout}ms) occurred waiting for port $port to be available');
+			server.close();
+		});
+		server.once("listening", function() {
+			status = true;
+			server.close();
+		});
+		server.once("close", () -> callback(status));
+		server.listen(port);
+	}
+
 	public static function getGlobalIp(callback:(ip:String)->Void):Void {
 		function onError(e):Void {
 			trace("Warning: connection error, server is local.");