Updates

Author: jkotalik

src/Servers/IIS/IIS/src/Core/IISHttpContext.FeatureCollection.cs

@@ -342,7 +342,10 @@ unsafe X509Certificate2 ITlsConnectionFeature.ClientCertificate
                 {
                     throw new ArgumentOutOfRangeException(nameof(value), CoreStrings.NonNegativeNumberOrNullRequired);
                 }
-
+                if (value > _options.IisMaxRequestSizeLimit)
+                {
+                    _logger.LogWarning("Cannot increase request size past IIS limit.");
+                }
                 MaxRequestBodySize = value;
             }
         }

src/Servers/IIS/IIS/src/IISServerOptions.cs

@@ -42,6 +42,8 @@ public class IISServerOptions
         // https://www.iis.net/configreference/system.webserver/security/requestfiltering/requestlimits#005
         private long? _maxRequestBodySize = 30000000;
 
+        internal long? IisMaxRequestSizeLimit;
+
         /// <summary>
         /// Gets or sets the maximum allowed size of any request body in bytes.
         /// When set to null, the maximum request body size is unlimited.

src/Servers/IIS/IIS/src/WebHostBuilderIISExtensions.cs

@@ -46,6 +46,12 @@ public static IWebHostBuilder UseIIS(this IWebHostBuilder hostBuilder)
                             options => {
                                 options.ServerAddresses = iisConfigData.pwzBindings.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
                                 options.ForwardWindowsAuthentication = iisConfigData.fWindowsAuthEnabled || iisConfigData.fBasicAuthEnabled;
+                                if (options.MaxRequestBodySize > iisConfigData.maxRequestBodySize)
+                                {
+                                    // Log warning and set the max to the IIS limit
+                                    options.MaxRequestBodySize = iisConfigData.maxRequestBodySize;
+                                }
+                                options.IisMaxRequestSizeLimit = iisConfigData.maxRequestBodySize;
                             }
                         );
                     });

src/Servers/IIS/IIS/test/Common.FunctionalTests/Inprocess/MaxRequestBodySizeTests.cs

@@ -30,5 +30,25 @@ public async Task MaxRequestBodySizeE2EWorks()
             var result = await deploymentResult.HttpClient.PostAsync("/ReadRequestBody", new StringContent("test"));
             Assert.Equal(HttpStatusCode.RequestEntityTooLarge, result.StatusCode);
         }
+
+        [ConditionalFact]
+        [RequiresNewHandler]
+        public async Task SetIISLimitMaxRequestBodySizeE2EWorks()
+        {
+            var deploymentParameters = Fixture.GetBaseDeploymentParameters();
+            deploymentParameters.ServerConfigActionList.Add(
+                (config, _) => {
+                    config
+                        .RequiredElement("system.webServer")
+                        .GetOrAdd("security")
+                        .GetOrAdd("requestFiltering")
+                        .GetOrAdd("requestLimits", "maxAllowedContentLength", "1");
+                });
+            var deploymentResult = await DeployAsync(deploymentParameters);
+
+            var result = await deploymentResult.HttpClient.PostAsync("/ReadRequestBody", new StringContent("test"));
+            // IIS returns a 404 instead of a 413... 
+            Assert.Equal(HttpStatusCode.NotFound, result.StatusCode);
+        }
     }
 }

src/Shared/HttpSys/RequestProcessing/RequestUriBuilder.cs

@@ -20,7 +20,7 @@ internal static class RequestUriBuilder
 
         public static string DecodeAndUnescapePath(Span<byte> rawUrlBytes)
         {
-            Debug.Assert(rawUrlBytes.Length > 0, "Length of the URL cannot be zero.");
+            Debug.Assert(rawUrlBytes.Length != 0, "Length of the URL cannot be zero.");
             var rawPath = RawUrlHelper.GetPath(rawUrlBytes);
 
             if (rawPath.Length == 0)