fix: expand ipv6 to support legacy devices

Author: abishekve

ThingConnect.Pulse.Server/Services/Monitoring/DiscoveryService.cs

@@ -26,7 +26,11 @@ public IEnumerable<string> ExpandCidr(string cidr)
     {
         if (cidr.Contains(":")) // IPv6 CIDR
         {
-            return ExpandCidrIPv6(cidr);
+            foreach (var ip in ExpandCidrIPv6(cidr))
+            {
+                yield return ip;
+            }
+            yield break;
         }
 
         Match match = CidrRegex.Match(cidr);
@@ -71,20 +75,22 @@ public IEnumerable<string> ExpandCidr(string cidr)
     }
 
     /// <summary>
-    /// Expand IPv6 CIDR into addresses (limited to /128 or /127 or /64 to avoid flooding)
+    /// Expand IPv6 CIDR into addresses (limited to /128, /127, or /64 to avoid flooding)
     /// </summary>
     private IEnumerable<string> ExpandCidrIPv6(string cidr)
     {
+        var result = new List<string>();
+
         try
         {
             string[] parts = cidr.Split('/');
             if (parts.Length != 2)
             {
                 _logger.LogWarning("Invalid IPv6 CIDR format: {Cidr}", cidr);
-                yield break;
+                return result;
             }
 
-            // Check for zone index (e.g., fe80::1%3)
+            // Handle zone index
             string hostPart = parts[0];
             string? zoneIndex = null;
             if (hostPart.Contains('%'))
@@ -94,35 +100,43 @@ private IEnumerable<string> ExpandCidrIPv6(string cidr)
                 zoneIndex = hostSplit[1];
             }
 
-            if (!IPAddress.TryParse(hostPart, out var ip)) yield break;
-            if (ip.AddressFamily != AddressFamily.InterNetworkV6) yield break;
+            if (!IPAddress.TryParse(hostPart, out var ip) || ip.AddressFamily != AddressFamily.InterNetworkV6)
+                return result;
 
-            int prefix = int.Parse(parts[1]);
+            if (!int.TryParse(parts[1], out int prefix))
+                return result;
+
+            string ApplyZone(string address) => zoneIndex != null ? $"{address}%{zoneIndex}" : address;
 
             if (prefix == 128)
-                yield return zoneIndex != null ? $"{ip}%{zoneIndex}" : ip.ToString();
+            {
+                result.Add(ApplyZone(ip.ToString()));
+            }
             else if (prefix == 127)
             {
                 byte[] bytes = ip.GetAddressBytes();
-                yield return zoneIndex != null ? $"{ip}%{zoneIndex}" : ip.ToString();
+                result.Add(ApplyZone(ip.ToString()));
 
+                // Flip last bit for second address
                 bytes[15] |= 1;
                 var ip2 = new IPAddress(bytes);
-                yield return zoneIndex != null ? $"{ip2}%{zoneIndex}" : ip2.ToString();
+                result.Add(ApplyZone(ip2.ToString()));
             }
             else if (prefix == 64)
-                yield return zoneIndex != null ? $"{ip}%{zoneIndex}" : ip.ToString();
+            {
+                result.Add(ApplyZone(ip.ToString()));
+            }
             else
             {
-                _logger.LogWarning(
-                    "Skipping IPv6 CIDR {Cidr} with prefix /{Prefix} to avoid massive expansion",
-                    cidr, prefix);
+                _logger.LogWarning("Skipping IPv6 CIDR {Cidr} with prefix /{Prefix}", cidr, prefix);
             }
         }
         catch (Exception ex)
         {
             _logger.LogWarning(ex, "Failed to expand IPv6 CIDR: {Cidr}", cidr);
         }
+
+        return result;
     }
 
     public IEnumerable<string> ExpandWildcard(string wildcard, int startRange = 1, int endRange = 254)
@@ -154,7 +168,13 @@ public IEnumerable<string> ExpandWildcard(string wildcard, int startRange = 1, i
     /// Expands a single IPv6 host into compressed (::) and full (xxxx:xxxx:....) forms.
     /// Handles optional zone index.
     /// </summary>
-    private IEnumerable<string> ExpandIPv6Host(string host)
+    public enum IPv6Format
+    {
+        Compressed,
+        Full
+    }
+
+    private IEnumerable<string> ExpandIPv6Host(string host, IPv6Format format = IPv6Format.Compressed)
     {
         string hostPart = host;
         string? zoneIndex = null;
@@ -169,27 +189,25 @@ private IEnumerable<string> ExpandIPv6Host(string host)
         if (!IPAddress.TryParse(hostPart, out var ip)) yield break;
         if (ip.AddressFamily != AddressFamily.InterNetworkV6) yield break;
 
-        // Compressed form
         string compressed = ip.ToString();
 
         // Full form (always 8 groups of 4 hex digits)
         string full = string.Join(":", Enumerable.Range(0, 8)
             .Select(i => ((ushort)((ip.GetAddressBytes()[i * 2] << 8) |
-                                ip.GetAddressBytes()[i * 2 + 1])).ToString("x4")));
+                                    ip.GetAddressBytes()[i * 2 + 1])).ToString("x4")));
+
+        string ApplyZone(string addr) => zoneIndex != null ? $"{addr}%{zoneIndex}" : addr;
 
-        if (zoneIndex != null)
+        if (format == IPv6Format.Compressed)
         {
-            yield return $"{compressed}%{zoneIndex}";
-            yield return $"{full}%{zoneIndex}";
+            yield return ApplyZone(compressed);
         }
-        else
+        else if (format == IPv6Format.Full)
         {
-            yield return compressed;
-            yield return full;
+            yield return ApplyZone(full);
         }
     }
 
-
    public async Task<IEnumerable<string>> ResolveHostnameAsync(string hostname, CancellationToken cancellationToken = default)
     {
         try

ThingConnect.Pulse.Server/Services/Monitoring/ProbeService.cs

@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using System.Net;
 using System.Net.NetworkInformation;
 using System.Net.Sockets;
 using ThingConnect.Pulse.Server.Data;