Fix detecting inherited WinHttpHandler (#2288)

Author: JamesNK

src/Shared/HttpRequestHelpers.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 
 // Copyright 2019 The gRPC Authors
 //
@@ -53,7 +53,7 @@ public static bool HasHttpHandlerType(HttpMessageHandler handler, string handler
 
     public static HttpMessageHandler? GetHttpHandlerType(HttpMessageHandler handler, string handlerTypeName)
     {
-        if (handler?.GetType().FullName == handlerTypeName)
+        if (IsType(handler.GetType(), handlerTypeName))
         {
             return handler;
         }
@@ -62,8 +62,7 @@ public static bool HasHttpHandlerType(HttpMessageHandler handler, string handler
         while (currentHandler is DelegatingHandler delegatingHandler)
         {
             currentHandler = delegatingHandler.InnerHandler;
-
-            if (currentHandler?.GetType().FullName == handlerTypeName)
+            if (currentHandler != null && IsType(currentHandler.GetType(), handlerTypeName))
             {
                 return currentHandler;
             }
@@ -72,6 +71,21 @@ public static bool HasHttpHandlerType(HttpMessageHandler handler, string handler
         return null;
     }
 
+    private static bool IsType(Type type, string handlerTypeName)
+    {
+        Type? currentType = type;
+        do
+        {
+            if (currentType.FullName == handlerTypeName)
+            {
+                return true;
+            }
+
+        } while ((currentType = currentType.BaseType) != null);
+
+        return false;
+    }
+
     public static bool HasHttpHandlerType<T>(HttpMessageHandler handler) where T : HttpMessageHandler
     {
         return GetHttpHandlerType<T>(handler) != null;

test/Grpc.Net.Client.Tests/GrpcChannelTests.cs

@@ -649,8 +649,11 @@ public void WinHttpHandler_UnsupportedWindows_Throw()
                 "For more information, see https://aka.ms/aspnet/grpc/netframework.");
     }
 
-    [Test]
-    public void WinHttpHandler_SupportedWindows_Success()
+#pragma warning disable CS0436 // Just need to have a type called WinHttpHandler to activate new behavior.
+    [TestCase(typeof(WinHttpHandler))]
+#pragma warning restore CS0436
+    [TestCase(typeof(WinHttpHandlerInherited))]
+    public void WinHttpHandler_SupportedWindows_Success(Type handlerType)
     {
         // Arrange
         var services = new ServiceCollection();
@@ -660,9 +663,7 @@ public void WinHttpHandler_SupportedWindows_Success()
             OSVersion = Version.Parse("10.0.20348.169")
         });
 
-#pragma warning disable CS0436 // Just need to have a type called WinHttpHandler to activate new behavior.
-        var winHttpHandler = new WinHttpHandler(new TestHttpMessageHandler());
-#pragma warning restore CS0436
+        var winHttpHandler = (HttpMessageHandler)Activator.CreateInstance(handlerType, new TestHttpMessageHandler())!;
 
         // Act
         var channel = GrpcChannel.ForAddress("https://localhost", new GrpcChannelOptions
@@ -675,6 +676,15 @@ public void WinHttpHandler_SupportedWindows_Success()
         Assert.AreEqual(HttpHandlerType.WinHttpHandler, channel.HttpHandlerType);
     }
 
+#pragma warning disable CS0436 // Just need to have a type called WinHttpHandler to activate new behavior.
+    private class WinHttpHandlerInherited : WinHttpHandler
+    {
+        public WinHttpHandlerInherited(HttpMessageHandler innerHandler) : base(innerHandler)
+        {
+        }
+    }
+#pragma warning restore CS0436
+
 #if SUPPORT_LOAD_BALANCING
     [Test]
     public void Resolver_SocketHttpHandlerWithConnectCallback_Error()