Fix: IP Scanner / Port Scanner / Ping Monitor: No message if all IP addresses are excluded and a hostname failed (R14)

The "all IP addresses are excluded" message was only shown if every
hostname could be resolved - also an excluded hostname that could not be
resolved suppressed it (e.g. "10.0.0.1; !10.0.0.1; !typo.lan"), and the
Ping Monitor then cleared the input. HostRangeHelper.ResolveAsync returns
the number of hosts removed by the exclusions; the message is shown if no
host is left and something was excluded, after the "could not be
resolved" message. The Ping Monitor keeps the input whenever no host is
left.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: BornToBeRoot

Source/NETworkManager.Models/Network/HostRangeHelper.cs

@@ -227,8 +227,12 @@ private static long GetIPv4RangeCount(IPAddress start, IPAddress end)
     ///     IP Scanner and the Port Scanner resolve the hostname themselves, a second entry would be scanned again).
     /// </param>
     /// <param name="cancellationToken">Token to monitor for cancellation requests.</param>
-    /// <returns>Sorted, distinct list of hosts and the hostnames that could not be resolved.</returns>
-    public static async Task<(List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved)>
+    /// <returns>
+    ///     Sorted, distinct list of hosts, the hostnames that could not be resolved and the number of hosts removed by
+    ///     the exclusions (e.g. to show that every IP address is excluded, also if a hostname could not be resolved).
+    /// </returns>
+    public static async Task<(List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved,
+            int excludedCount)>
         ResolveAsync(IEnumerable<string> hosts, bool dnsResolveHostnamePreferIPv4, bool keepAllHostnames,
             CancellationToken cancellationToken)
     {
@@ -350,11 +354,20 @@ await Parallel.ForEachAsync(Enumerable.Range(0, exclusionInputs.Count),
 
         var activeExclusions = exclusions.Where(x => x != null).ToList();
 
+        var excludedCount = 0;
+
         if (activeExclusions.Count > 0)
+        {
+            var count = result.Count;
+
             result = [.. result.Where(host => !activeExclusions.Any(isExcluded => isExcluded(host.ipAddress)))];
 
+            excludedCount = count - result.Count;
+        }
+
         return (result,
-            [.. hostnameNotResolvedPerInput.Concat(exclusionHostnameNotResolved).Where(x => x != null)]);
+            [.. hostnameNotResolvedPerInput.Concat(exclusionHostnameNotResolved).Where(x => x != null)],
+            excludedCount);
     }
 
     /// <summary>

Source/NETworkManager.Tests/Network/HostRangeHelperExclusionTests.cs

@@ -10,7 +10,7 @@ public class HostRangeHelperExclusionTests
 {
     private static async Task<string[]> ResolveAsync(string input)
     {
-        var (hosts, _) = await HostRangeHelper.ResolveAsync(HostRangeHelper.CreateListFromInput(input), true, false,
+        var (hosts, _, _) = await HostRangeHelper.ResolveAsync(HostRangeHelper.CreateListFromInput(input), true, false,
             CancellationToken.None);
 
         return [.. hosts.Select(x => x.ipAddress.ToString())];
@@ -38,6 +38,20 @@ public async Task ResolveAsync_OnlyExclusions_NoHosts()
         Assert.Empty(await ResolveAsync("!10.0.0.1"));
     }
 
+    [Theory]
+    [InlineData("10.0.0.1; !10.0.0.1", 1)]
+    [InlineData("10.0.0.0/30; !10.0.0.1-2", 2)]
+    [InlineData("10.0.0.1-3; !10.0.0.0/8", 3)]
+    [InlineData("10.0.0.1-3; !192.168.0.1", 0)]
+    [InlineData("10.0.0.1-3", 0)]
+    public async Task ResolveAsync_ExcludedCount(string input, int expected)
+    {
+        var (_, _, excludedCount) = await HostRangeHelper.ResolveAsync(HostRangeHelper.CreateListFromInput(input),
+            true, false, CancellationToken.None);
+
+        Assert.Equal(expected, excludedCount);
+    }
+
     [Theory]
     [InlineData("10.0.0.0/24; !10.0.0.1", 256)]
     [InlineData("10.0.0.0/24; !10.0.0.0/8", 256)]

Source/NETworkManager/ViewModels/IPScannerViewModel.cs

@@ -857,7 +857,7 @@ private async Task Start()
 
         // Resolve hostnames and convert the ports. Start() is fire-and-forget, so every exception has to be
         // handled here - otherwise the scan would never end (IsRunning stays true).
-        (List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved) hosts;
+        (List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved, int excludedCount) hosts;
         int[] ports;
         int[] webPagePorts;
 
@@ -892,10 +892,12 @@ private async Task Start()
             IsStatusMessageDisplayed = true;
         }
 
-        // The input has an inclusion (validated) - without unresolved hostnames, the exclusions removed every host
-        if (hosts.hosts.Count == 0 && hosts.hostnamesNotResolved.Count == 0)
+        // The exclusions removed every host (also if hostnames could not be resolved, keep their message)
+        if (hosts.hosts.Count == 0 && hosts.excludedCount > 0)
         {
-            StatusMessage = Strings.AllIPAddressesAreExcludedMessage;
+            StatusMessage = IsStatusMessageDisplayed
+                ? StatusMessage + Environment.NewLine + Strings.AllIPAddressesAreExcludedMessage
+                : Strings.AllIPAddressesAreExcludedMessage;
             IsStatusMessageDisplayed = true;
         }
 

Source/NETworkManager/ViewModels/PingMonitorHostViewModel.cs

@@ -319,7 +319,7 @@ public async Task Start()
         _cancellationTokenSource = new CancellationTokenSource();
 
         // Resolve hostnames
-        (List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved) hosts;
+        (List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved, int excludedCount) hosts;
 
         try
         {
@@ -342,13 +342,19 @@ public async Task Start()
             IsStatusMessageDisplayed = true;
         }
 
-        // The input has an inclusion (validated) - without unresolved hostnames, the exclusions removed every host:
-        // nothing to add, the input is kept to correct it
-        if (hosts.hosts.Count == 0 && hosts.hostnamesNotResolved.Count == 0)
+        // The exclusions removed every host (also if hostnames could not be resolved, keep their message)
+        if (hosts.hosts.Count == 0 && hosts.excludedCount > 0)
         {
-            StatusMessage = Strings.AllIPAddressesAreExcludedMessage;
+            StatusMessage = IsStatusMessageDisplayed
+                ? StatusMessage + Environment.NewLine + Strings.AllIPAddressesAreExcludedMessage
+                : Strings.AllIPAddressesAreExcludedMessage;
             IsStatusMessageDisplayed = true;
+        }
 
+        // No host left (hostnames that could not be resolved, everything excluded): nothing to add, the input is kept
+        // to correct it
+        if (hosts.hosts.Count == 0)
+        {
             IsRunning = false;
 
             return;

Source/NETworkManager/ViewModels/PortScannerViewModel.cs

@@ -920,7 +920,7 @@ private async Task Start()
 
         // Resolve hostnames and convert the ports. Start() is fire-and-forget, so every exception has to be
         // handled here - otherwise the scan would never end (IsRunning stays true).
-        (List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved) hosts;
+        (List<(IPAddress ipAddress, string hostname)> hosts, List<string> hostnamesNotResolved, int excludedCount) hosts;
         int[] ports;
 
         try
@@ -947,8 +947,8 @@ private async Task Start()
             AddStatusMessage(
                 $"{Strings.TheFollowingHostnamesCouldNotBeResolved} {string.Join(", ", hosts.hostnamesNotResolved)}");
 
-        // The input has an inclusion (validated) - without unresolved hostnames, the exclusions removed every host
-        if (hosts.hosts.Count == 0 && hosts.hostnamesNotResolved.Count == 0)
+        // The exclusions removed every host (also if hostnames could not be resolved)
+        if (hosts.hosts.Count == 0 && hosts.excludedCount > 0)
             AddStatusMessage(Strings.AllIPAddressesAreExcludedMessage);
 
         PortsToScan = ports.Length * hosts.hosts.Count;