Improve verification of IPv4-mapped IPv6 addresses in IAccessRule

src/Smdn.Net.MuninNode/Smdn.Net.MuninNode/AddressListAccessRule.cs

@@ -9,10 +9,15 @@ namespace Smdn.Net.MuninNode;
 
 internal sealed class AddressListAccessRule : IAccessRule {
   private readonly IReadOnlyList<IPAddress> addressListAllowFrom;
+  private readonly bool shouldConsiderIPv4MappedIPv6Address;
 
-  public AddressListAccessRule(IReadOnlyList<IPAddress> addressListAllowFrom)
+  public AddressListAccessRule(
+    IReadOnlyList<IPAddress> addressListAllowFrom,
+    bool shouldConsiderIPv4MappedIPv6Address
+  )
   {
     this.addressListAllowFrom = addressListAllowFrom ?? throw new ArgumentNullException(nameof(addressListAllowFrom));
+    this.shouldConsiderIPv4MappedIPv6Address = shouldConsiderIPv4MappedIPv6Address;
   }
 
   public bool IsAcceptable(IPEndPoint remoteEndPoint)
@@ -23,10 +28,22 @@ public bool IsAcceptable(IPEndPoint remoteEndPoint)
     var remoteAddress = remoteEndPoint.Address;
 
     foreach (var addressAllowFrom in addressListAllowFrom) {
-      if (addressAllowFrom.AddressFamily == AddressFamily.InterNetwork) {
-        // test for client acceptability by IPv4 address
-        if (remoteAddress.IsIPv4MappedToIPv6)
+      if (shouldConsiderIPv4MappedIPv6Address) {
+        if (
+          remoteAddress.IsIPv4MappedToIPv6 &&
+          addressAllowFrom.AddressFamily == AddressFamily.InterNetwork
+        ) {
+          // test for client acceptability by IPv4 address
           remoteAddress = remoteAddress.MapToIPv4();
+        }
+
+        if (
+          remoteAddress.AddressFamily == AddressFamily.InterNetwork &&
+          addressAllowFrom.AddressFamily == AddressFamily.InterNetworkV6
+        ) {
+          // test for client acceptability by IPv6 address
+          remoteAddress = remoteAddress.MapToIPv6();
+        }
       }
 
       if (addressAllowFrom.Equals(remoteAddress))

src/Smdn.Net.MuninNode/Smdn.Net.MuninNode/IAccessRuleServiceCollectionExtensions.cs

@@ -15,11 +15,29 @@ public static class IAccessRuleServiceCollectionExtensions {
   public static IServiceCollection AddMuninNodeAccessRule(
     this IServiceCollection services,
     IReadOnlyList<IPAddress> addressListAllowFrom
+  )
+    => AddMuninNodeAccessRule(
+      services: services,
+      addressListAllowFrom: addressListAllowFrom ?? throw new ArgumentNullException(nameof(addressListAllowFrom)),
+      shouldConsiderIPv4MappedIPv6Address: true
+    );
+
+  /// <param name="services">The <see cref="IServiceCollection"/> to add services to.</param>
+  /// <param name="addressListAllowFrom">The <see cref="IReadOnlyList{IPAddress}"/> indicates the read-only list of addresses allowed to access <see cref="NodeBase"/>.</param>
+  /// <param name="shouldConsiderIPv4MappedIPv6Address">
+  /// The value indicating whether the address resolution to be aware or not to be aware that
+  /// the IP address is an IPv4-mapped IPv6 address when comparing IP address.
+  /// </param>
+  public static IServiceCollection AddMuninNodeAccessRule(
+    this IServiceCollection services,
+    IReadOnlyList<IPAddress> addressListAllowFrom,
+    bool shouldConsiderIPv4MappedIPv6Address
   )
     => AddMuninNodeAccessRule(
       services: services ?? throw new ArgumentNullException(nameof(services)),
       accessRule: new AddressListAccessRule(
-        addressListAllowFrom: addressListAllowFrom ?? throw new ArgumentNullException(nameof(addressListAllowFrom))
+        addressListAllowFrom: addressListAllowFrom ?? throw new ArgumentNullException(nameof(addressListAllowFrom)),
+        shouldConsiderIPv4MappedIPv6Address: shouldConsiderIPv4MappedIPv6Address
       )
     );
 

src/Smdn.Net.MuninNode/Smdn.Net.MuninNode/LocalNode.Create.cs

@@ -128,7 +128,7 @@ public static LocalNode Create(
       pluginProvider: pluginProvider ?? throw new ArgumentNullException(nameof(pluginProvider)),
       hostName: string.IsNullOrEmpty(hostName) ? DefaultHostName : hostName,
       port: port,
-      accessRule: addressListAllowFrom is null ? null : new AddressListAccessRule(addressListAllowFrom),
+      accessRule: addressListAllowFrom is null ? null : new AddressListAccessRule(addressListAllowFrom, shouldConsiderIPv4MappedIPv6Address: true),
       serviceProvider: serviceProvider
     );
 }

tests/Smdn.Net.MuninNode/Smdn.Net.MuninNode/IAccessRuleServiceCollectionExtensions.cs

@@ -49,4 +49,70 @@ public void AddMuninNodeAccessRule_IAccessRule_ArgumentNull()
       () => services.AddMuninNodeAccessRule((IAccessRule)null!)
     );
   }
+
+  private static System.Collections.IEnumerable YieldTestCases_AddMuninNodeAccessRule_IReadOnlyListOfIPAddress_ShouldConsiderIPv4MappedIPv6Address()
+  {
+    var addressIPv4 = IPAddress.Parse("192.0.2.255");
+    var addressIPv6MappedIPv4 = IPAddress.Parse("::ffff:192.0.2.255");
+
+    foreach (var shouldConsiderIPv4MappedIPv6Address in new[] { true, false }) {
+      yield return new object[] {
+        new[] { addressIPv4 },
+        shouldConsiderIPv4MappedIPv6Address,
+        addressIPv6MappedIPv4,
+        shouldConsiderIPv4MappedIPv6Address
+      };
+
+      yield return new object[] {
+        new[] { addressIPv6MappedIPv4 },
+        shouldConsiderIPv4MappedIPv6Address,
+        addressIPv4,
+        shouldConsiderIPv4MappedIPv6Address
+      };
+
+      yield return new object[] {
+        new[] { addressIPv4, addressIPv6MappedIPv4 },
+        shouldConsiderIPv4MappedIPv6Address,
+        addressIPv6MappedIPv4,
+        true
+      };
+
+      yield return new object[] {
+        new[] { addressIPv4, addressIPv6MappedIPv4 },
+        shouldConsiderIPv4MappedIPv6Address,
+        addressIPv4,
+        true
+      };
+
+      yield return new object[] {
+        new[] { addressIPv4, addressIPv6MappedIPv4 },
+        shouldConsiderIPv4MappedIPv6Address,
+        IPAddress.Loopback,
+        false
+      };
+    }
+  }
+
+  [TestCaseSource(nameof(YieldTestCases_AddMuninNodeAccessRule_IReadOnlyListOfIPAddress_ShouldConsiderIPv4MappedIPv6Address))]
+  public void AddMuninNodeAccessRule_IReadOnlyListOfIPAddress_ShouldConsiderIPv4MappedIPv6Address(
+    IReadOnlyList<IPAddress> addressListAllowFrom,
+    bool shouldConsiderIPv4MappedIPv6Address,
+    IPAddress remoteAddress,
+    bool expected
+  )
+  {
+    var services = new ServiceCollection();
+
+    services.AddMuninNodeAccessRule(
+      addressListAllowFrom: addressListAllowFrom,
+      shouldConsiderIPv4MappedIPv6Address: shouldConsiderIPv4MappedIPv6Address
+    );
+
+    var accessRule = services.BuildServiceProvider().GetRequiredService<IAccessRule>();
+
+    Assert.That(
+      accessRule.IsAcceptable(new(remoteAddress, port: 0)),
+      Is.EqualTo(expected)
+    );
+  }
 }