PR feedback

Author: JamesNK

src/Middleware/CORS/samples/SampleDestination/Program.cs

@@ -12,33 +12,36 @@ public class Program
     {
         public static void Main(string[] args)
         {
-            Type startupType = null;
-
-            var startup = Environment.GetEnvironmentVariable("CORS_STARTUP");
-            switch (startup)
-            {
-                case "Startup":
-                    startupType = typeof(Startup);
-                    break;
-                case "StartupWithoutEndpointRouting":
-                    startupType = typeof(StartupWithoutEndpointRouting);
-                    break;
-            }
-
-            if (startupType == null)
-            {
-                throw new InvalidOperationException("Could not resolve the startup type. Unexpected CORS_STARTUP environment variable.");
-            }
-
             var host = new WebHostBuilder()
                 .UseKestrel()
                 .UseUrls("http://+:9000")
                 .UseContentRoot(Directory.GetCurrentDirectory())
                 .ConfigureLogging(factory => factory.AddConsole())
-                .UseStartup(startupType)
+                .UseStartup(GetStartupType())
                 .Build();
 
             host.Run();
         }
+
+        private static Type GetStartupType()
+        {
+            var startup = Environment.GetEnvironmentVariable("CORS_STARTUP");
+            if (startup == null)
+            {
+                return typeof(Startup);
+            }
+            else
+            {
+                switch (startup)
+                {
+                    case "Startup":
+                        return typeof(Startup);
+                    case "StartupWithoutEndpointRouting":
+                        return typeof(StartupWithoutEndpointRouting);
+                }
+            }
+
+            throw new InvalidOperationException("Could not resolve the startup type. Unexpected CORS_STARTUP environment variable.");
+        }
     }
 }

src/Middleware/CORS/src/Infrastructure/CorsEndpointConventionBuilderExtensions.cs

@@ -7,8 +7,17 @@
 
 namespace Microsoft.AspNetCore.Builder
 {
+    /// <summary>
+    /// CORS extension methods for <see cref="IEndpointConventionBuilder"/>.
+    /// </summary>
     public static class CorsEndpointConventionBuilderExtensions
     {
+        /// <summary>
+        /// Adds a CORS policy with the specified name to the endpoint(s).
+        /// </summary>
+        /// <param name="builder">The endpoint convention builder.</param>
+        /// <param name="policyName">The CORS policy name.</param>
+        /// <returns>The original convention builder parameter.</returns>
         public static IEndpointConventionBuilder WithCorsPolicy(this IEndpointConventionBuilder builder, string policyName)
         {
             if (builder == null)

src/Middleware/CORS/src/Infrastructure/CorsMiddleware.cs

@@ -16,6 +16,9 @@ namespace Microsoft.AspNetCore.Cors.Infrastructure
     /// </summary>
     public class CorsMiddleware
     {
+        // Property key is used by MVC filters to check if CORS middleware has run
+        private const string CorsMiddlewareInvokedKey = "__CorsMiddlewareInvoked";
+
         private readonly Func<object, Task> OnResponseStartingDelegate = OnResponseStarting;
         private readonly RequestDelegate _next;
         private readonly CorsPolicy _policy;
@@ -132,6 +135,9 @@ private async Task InvokeCore(HttpContext context, ICorsPolicyProvider corsPolic
             //    fetch policy by name, prioritizing it above policy on middleware
             // 3. If there is no policy on middleware then use name on middleware
 
+            // Flag to indicate to other systems, e.g. MVC, that CORS middleware was run for this request
+            context.Items[CorsMiddlewareInvokedKey] = true;
+
             var endpoint = context.GetEndpoint();
 
             // Get the most significant CORS metadata for the endpoint