feat(gateway): validate MxGateway:Tls options

src/ZB.MOM.WW.MxGateway.Server/Configuration/GatewayOptionsValidator.cs

@@ -26,6 +26,7 @@ public sealed class GatewayOptionsValidator : IValidateOptions<GatewayOptions>
         ValidateDashboard(options.Dashboard, failures);
         ValidateProtocol(options.Protocol, failures);
         ValidateAlarms(options.Alarms, failures);
+        ValidateTls(options.Tls, failures);
 
         return failures.Count == 0
             ? ValidateOptionsResult.Success
@@ -262,6 +263,31 @@ public sealed class GatewayOptionsValidator : IValidateOptions<GatewayOptions>
         }
     }
 
+    private const int MinimumCertValidityYears = 1;
+    private const int MaximumCertValidityYears = 100;
+
+    private static void ValidateTls(TlsOptions options, List<string> failures)
+    {
+        if (options.ValidityYears is < MinimumCertValidityYears or > MaximumCertValidityYears)
+        {
+            failures.Add(
+                $"MxGateway:Tls:ValidityYears must be between {MinimumCertValidityYears} and {MaximumCertValidityYears}.");
+        }
+
+        AddIfInvalidPath(
+            options.SelfSignedCertPath,
+            "MxGateway:Tls:SelfSignedCertPath must be a valid filesystem path.",
+            failures);
+
+        foreach (string dns in options.AdditionalDnsNames)
+        {
+            if (string.IsNullOrWhiteSpace(dns))
+            {
+                failures.Add("MxGateway:Tls:AdditionalDnsNames entries must be non-blank.");
+            }
+        }
+    }
+
     private static void ValidateProtocol(ProtocolOptions options, List<string> failures)
     {
         if (options.WorkerProtocolVersion != GatewayContractInfo.WorkerProtocolVersion)

src/ZB.MOM.WW.MxGateway.Tests/Configuration/GatewayOptionsValidatorTests.cs

@@ -0,0 +1,59 @@
+using Microsoft.Extensions.Options;
+using ZB.MOM.WW.MxGateway.Server.Configuration;
+
+namespace ZB.MOM.WW.MxGateway.Tests.Configuration;
+
+public sealed class GatewayOptionsValidatorTests
+{
+    // Constructs the minimal valid GatewayOptions by relying on each sub-option's
+    // design-default values; those defaults are validated separately in GatewayOptionsTests.
+    private static GatewayOptions ValidOptions() => new();
+
+    private static GatewayOptions CloneWithTls(GatewayOptions source, TlsOptions tls)
+        => new()
+        {
+            Authentication = source.Authentication,
+            Ldap = source.Ldap,
+            Worker = source.Worker,
+            Sessions = source.Sessions,
+            Events = source.Events,
+            Dashboard = source.Dashboard,
+            Protocol = source.Protocol,
+            Alarms = source.Alarms,
+            Tls = tls,
+        };
+
+    [Fact]
+    public void Validate_Succeeds_WithDefaultTlsOptions()
+    {
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(null, ValidOptions());
+        Assert.True(result.Succeeded);
+    }
+
+    [Fact]
+    public void Validate_Fails_WhenTlsValidityYearsOutOfRange()
+    {
+        GatewayOptions withBadTls = CloneWithTls(ValidOptions(), new TlsOptions { ValidityYears = 0 });
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(null, withBadTls);
+        Assert.True(result.Failed);
+        Assert.Contains(result.Failures!, f => f.Contains("MxGateway:Tls:ValidityYears"));
+    }
+
+    [Fact]
+    public void Validate_Fails_WhenTlsValidityYearsTooLarge()
+    {
+        GatewayOptions withBadTls = CloneWithTls(ValidOptions(), new TlsOptions { ValidityYears = 101 });
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(null, withBadTls);
+        Assert.True(result.Failed);
+        Assert.Contains(result.Failures!, f => f.Contains("MxGateway:Tls:ValidityYears"));
+    }
+
+    [Fact]
+    public void Validate_Fails_WhenAdditionalDnsNameBlank()
+    {
+        GatewayOptions options = CloneWithTls(ValidOptions(), new TlsOptions { AdditionalDnsNames = [" "] });
+        ValidateOptionsResult result = new GatewayOptionsValidator().Validate(null, options);
+        Assert.True(result.Failed);
+        Assert.Contains(result.Failures!, f => f.Contains("MxGateway:Tls:AdditionalDnsNames"));
+    }
+}