Do not return 200 for exceptions

samples/NativeIISSample/Properties/launchSettings.json

@@ -12,6 +12,7 @@
       "commandName": "Executable",
       "executablePath": "$(IISExpressPath)",
       "commandLineArgs": "$(IISExpressArguments)",
+      "nativeDebugging": true,
       "environmentVariables": {
         "IIS_SITE_PATH": "$(MSBuildThisFileDirectory)",
         "ANCM_PATH": "$(TargetDir)$(AncmPath)",

src/Microsoft.AspNetCore.Server.IISIntegration/Server/IISHttpContext.cs

@@ -332,10 +332,12 @@ namespace Microsoft.AspNetCore.Server.IISIntegration
         public unsafe void SendResponseHeaders(bool appCompleted)
         {
             // Verifies we have sent the statuscode before writing a header
-            var reasonPhraseBytes = Encoding.UTF8.GetBytes(ReasonPhrase ?? ReasonPhrases.GetReasonPhrase(StatusCode));
+            var reasonPhrase = string.IsNullOrWhiteSpace(ReasonPhrase) ? ReasonPhrases.GetReasonPhrase(StatusCode) : ReasonPhrase;
+            var reasonPhraseBytes = Encoding.UTF8.GetBytes(reasonPhrase);
 
             fixed (byte* pReasonPhrase = reasonPhraseBytes)
             {
+                Debug.Assert((IntPtr)pReasonPhrase != IntPtr.Zero);
                 // This copies data into the underlying buffer
                 NativeMethods.http_set_response_status_code(_pInProcessHandler, (ushort)StatusCode, pReasonPhrase);
             }

test/IISIntegration.FunctionalTests/Inprocess/ResponseHeaderTests.cs

@@ -40,5 +40,13 @@ namespace Microsoft.AspNetCore.Server.IISIntegration.FunctionalTests
             Assert.Equal("1", headerValues.First());
             Assert.Equal("2", headerValues.Last());
         }
+
+        [ConditionalFact]
+        public async Task ErrorCodeIsSetForExceoptionDuringRequest()
+        {
+            var response = await _fixture.Client.GetAsync("Throw");
+            Assert.Equal(HttpStatusCode.InternalServerError, response.StatusCode);
+            Assert.Equal("Internal Server Error", response.ReasonPhrase);
+        }
     }
 }

test/IISTestSite/Startup.cs

@@ -5,6 +5,7 @@ using System;
 using System.Diagnostics;
 using System.IO;
 using System.Net;
+using System.Reflection;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -23,33 +24,16 @@ namespace IISTestSite
     {
         public void Configure(IApplicationBuilder app)
         {
-            app.Map("/ServerVariable", ServerVariable);
+            foreach (var method in GetType().GetMethods(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
-            app.Map("/AuthenticationAnonymous", AuthenticationAnonymous);
+            {
-            app.Map("/AuthenticationRestricted", AuthenticationRestricted);
+                var parameters = method.GetParameters();
-            app.Map("/AuthenticationForbidden", AuthenticationForbidden);
+                if (method.Name != nameof(Configure) &&
-            app.Map("/AuthenticationRestrictedNTLM", AuthenticationRestrictedNTLM);
+                    parameters.Length == 1 &&
-            app.Map("/FeatureCollectionSetRequestFeatures", FeatureCollectionSetRequestFeatures);
+                    parameters[0].ParameterType == typeof(IApplicationBuilder))
-            app.Map("/FeatureCollectionSetResponseFeatures", FeatureCollectionSetResponseFeatures);
+                {
-            app.Map("/FeatureCollectionSetConnectionFeatures", FeatureCollectionSetConnectionFeatures);
+                    app.Map("/" + method.Name, innerAppBuilder => method.Invoke(this, new[] { innerAppBuilder }));
-            app.Map("/HelloWorld", HelloWorld);
+                }
-            app.Map("/LargeResponseBody", LargeResponseBody);
+            }
-            app.Map("/ResponseHeaders", ResponseHeaders);
-            app.Map("/ResponseInvalidOrdering", ResponseInvalidOrdering);
-            app.Map("/CheckEnvironmentVariable", CheckEnvironmentVariable);
-            app.Map("/CheckEnvironmentLongValueVariable", CheckEnvironmentLongValueVariable);
-            app.Map("/CheckAppendedEnvironmentVariable", CheckAppendedEnvironmentVariable);
-            app.Map("/CheckRemoveAuthEnvironmentVariable", CheckRemoveAuthEnvironmentVariable);
-            app.Map("/ReadAndWriteSynchronously", ReadAndWriteSynchronously);
-            app.Map("/ReadAndWriteEcho", ReadAndWriteEcho);
-            app.Map("/ReadAndWriteCopyToAsync", ReadAndWriteCopyToAsync);
-            app.Map("/ReadAndWriteEchoTwice", ReadAndWriteEchoTwice);
-            app.Map("/ReadAndWriteSlowConnection", ReadAndWriteSlowConnection);
-            app.Map("/WebsocketRequest", WebsocketRequest);
-            app.Map("/UpgradeFeatureDetection", UpgradeFeatureDetection);
-            app.Map("/TestInvalidReadOperations", TestInvalidReadOperations);
-            app.Map("/TestInvalidWriteOperations", TestInvalidWriteOperations);
-            app.Map("/TestReadOffsetWorks", TestReadOffsetWorks);
-            app.Map("/LargeResponseFile", LargeResponseFile);
         }
 
         private void ServerVariable(IApplicationBuilder app)
@@ -229,6 +213,11 @@ namespace IISTestSite
             });
         }
 
+        private void Throw(IApplicationBuilder app)
+        {
+            app.Run(ctx => { throw new Exception(); });
+        }
+
         private void HelloWorld(IApplicationBuilder app)
         {
             app.Run(async ctx =>