IP address check for Unity IP address and ROS IP address

com.unity.robotics.ros-tcp-connector/Editor/ROSSettingsEditor.cs

@@ -17,7 +17,6 @@ public static void OpenWindow()
 
         GameObject prefabObj;
         ROSConnection prefab;
-
         protected virtual void OnGUI()
         {
             if (prefab == null)
@@ -48,6 +47,15 @@ protected virtual void OnGUI()
                 new GUIContent("Override Unity IP Address", "If blank, determine IP automatically."),
                 prefab.overrideUnityIP);
             prefab.unityPort = EditorGUILayout.IntField("Unity Port", prefab.unityPort);
+            if ((prefab.overrideUnityIP != "" && !ROSConnection.IPFormatIsCorrect(prefab.overrideUnityIP)))
+            {   
+                EditorGUILayout.HelpBox("Unity Override IP invalid", MessageType.Warning);
+            }
+
+            if(!ROSConnection.IPFormatIsCorrect(prefab.rosIPAddress))
+            {
+                EditorGUILayout.HelpBox("ROS IP is invalid", MessageType.Warning);
+            }
             EditorGUILayout.Space();
             EditorGUILayout.LabelField("If awaiting a service response:", EditorStyles.boldLabel);
             prefab.awaitDataMaxRetries = EditorGUILayout.IntField(

com.unity.robotics.ros-tcp-connector/Runtime/TcpConnector/ROSConnection.cs

@@ -8,6 +8,7 @@
 using System.Text;
 using System.Threading.Tasks;
 using Unity.Robotics.ROSTCPConnector.MessageGeneration;
+using System.Globalization;
 using UnityEngine;
 using UnityEngine.Serialization;
 
@@ -224,11 +225,15 @@ void OnEnable()
 
         private void Start()
         {
+            if(!IPFormatIsCorrect(rosIPAddress))
+                Debug.LogError("ROS IP address is not correct");
             InitializeHUD();
             Subscribe<MRosUnityError>(ERROR_TOPIC_NAME, RosUnityErrorCallback);
 
             if (overrideUnityIP != "")
             {
+                if(!IPFormatIsCorrect(overrideUnityIP))
+                    Debug.LogError("Override Unity IP address is not correct");
                 StartMessageServer(overrideUnityIP, unityPort); // no reason to wait, if we already know the IP
             }
 
@@ -588,5 +593,33 @@ private void WriteDataStaggered(NetworkStream networkStream, string rosTopicName
                 networkStream.Write(segmentData, 0, segmentData.Length);
             }
         }
+
+        public static bool IPFormatIsCorrect(string ipAddress)
+        {
+            if(ipAddress == null || ipAddress == "")
+                return false;
+
+            // If IP address is set using static lookup tables https://man7.org/linux/man-pages/man5/hosts.5.html
+            if(Char.IsLetter(ipAddress[0]))
+            {
+                foreach(Char subChar in ipAddress)
+                {
+                    if(!(Char.IsLetterOrDigit(subChar)  || subChar == '-'|| subChar == '.'))
+                        return false;
+                }
+
+                if(!Char.IsLetterOrDigit(ipAddress[ipAddress.Length - 1]))
+                    return false;
+                return true;
+            }
+
+            string[] subAdds = ipAddress.Split('.');
+            if(subAdds.Length != 4)
+            {
+                return false;
+            }
+            IPAddress parsedipAddress;
+            return IPAddress.TryParse(ipAddress, out parsedipAddress);
+        }
     }
 }