Ip adress sanitization for MP Menu screen

NebulaPatcher/Patches/Dynamic/UIMainMenu_Patch.cs

@@ -171,6 +171,18 @@ private static void OnJoinGameButtonClick()
             string ip = parts[0];
             int port;
 
+            //remove copy and paste mistakes and update the textbox to prevent user confusion in case of invalid ip address
+            ip = SanitizeIpAddressString(ip);
+            hostIPAdressInput.text = parts.Length == 1 ? ip : ip + ":" + parts[1];
+
+            if (!System.Net.IPAddress.TryParse(ip, out _))
+            {
+                //log, notify user and early return to prevent crash on invalid strings
+                InGamePopup.ShowWarning("Invalid connection string", "Note: This mod currently only accepts IPv4 Addresses.", "OK");
+                Log.Info($"IP String {ip} is not a valid IPv4 String");
+                return;
+            }
+
             if (parts.Length == 1)
             {
                 port = Config.DefaultPort;
@@ -181,6 +193,7 @@ private static void OnJoinGameButtonClick()
                 return;
             }
 
+
             // TODO: Should display a loader during the connection and only open the game once the player is connected to the server.
             multiplayerMenu.gameObject.SetActive(false);
 
@@ -195,5 +208,18 @@ private static void OnJoinGameBackButtonClick()
             multiplayerMenu.gameObject.SetActive(false);
             UIRoot.instance.OpenMainMenuUI();
         }
+
+        private static string SanitizeIpAddressString(string ipAddr)
+        {
+            //remove simple copy&paste errors
+            string cleanedIpAddr = new System.Text.StringBuilder(ipAddr)
+                .Replace("\r", string.Empty)
+                .Replace("\n", string.Empty)
+                .Replace(" ", string.Empty)
+                .Replace("\t", string.Empty)
+                .ToString();
+
+            return cleanedIpAddr;
+        }
     }
 }