Allow file middlewares to run if there's an endpoint with a null request delegate (#42458)

* Allow file middlewares to run if there's an endpoint with a null request delegate #42413

* Ensure EndpointMiddleware checks AuthZ/CORS metadata even if endpoint.RequestDelegate is null

* Update null equality check to use "is"

* Added tests for StaticFileMiddleware changes

* Add tests for DefaultFiles/DirectoryBrowser middleware

* Add endpoint middleware test

src/Http/Routing/src/EndpointMiddleware.cs

@@ -31,41 +31,44 @@ internal sealed partial class EndpointMiddleware
     public Task Invoke(HttpContext httpContext)
     {
         var endpoint = httpContext.GetEndpoint();
-        if (endpoint?.RequestDelegate != null)
+        if (endpoint is not null)
         {
             if (!_routeOptions.SuppressCheckForUnhandledSecurityMetadata)
             {
-                if (endpoint.Metadata.GetMetadata<IAuthorizeData>() != null &&
+                if (endpoint.Metadata.GetMetadata<IAuthorizeData>() is not null &&
                     !httpContext.Items.ContainsKey(AuthorizationMiddlewareInvokedKey))
                 {
                     ThrowMissingAuthMiddlewareException(endpoint);
                 }
 
-                if (endpoint.Metadata.GetMetadata<ICorsMetadata>() != null &&
+                if (endpoint.Metadata.GetMetadata<ICorsMetadata>() is not null &&
                     !httpContext.Items.ContainsKey(CorsMiddlewareInvokedKey))
                 {
                     ThrowMissingCorsMiddlewareException(endpoint);
                 }
             }
 
-            Log.ExecutingEndpoint(_logger, endpoint);
-
-            try
+            if (endpoint.RequestDelegate is not null)
             {
-                var requestTask = endpoint.RequestDelegate(httpContext);
-                if (!requestTask.IsCompletedSuccessfully)
+                Log.ExecutingEndpoint(_logger, endpoint);
+
+                try
                 {
-                    return AwaitRequestTask(endpoint, requestTask, _logger);
+                    var requestTask = endpoint.RequestDelegate(httpContext);
+                    if (!requestTask.IsCompletedSuccessfully)
+                    {
+                        return AwaitRequestTask(endpoint, requestTask, _logger);
+                    }
                 }
-            }
-            catch (Exception exception)
-            {
+                catch (Exception exception)
+                {
+                    Log.ExecutedEndpoint(_logger, endpoint);
+                    return Task.FromException(exception);
+                }
+
                 Log.ExecutedEndpoint(_logger, endpoint);
-                return Task.FromException(exception);
+                return Task.CompletedTask;
             }
-
-            Log.ExecutedEndpoint(_logger, endpoint);
-            return Task.CompletedTask;
         }
 
         return _next(httpContext);

src/Http/Routing/test/UnitTests/EndpointMiddlewareTest.cs

@@ -120,6 +120,35 @@ public class EndpointMiddlewareTest
         Assert.Equal(expected, ex.Message);
     }
 
+    [Fact]
+    public async Task Invoke_WithEndpointWithNullRequestDelegate_ThrowsIfAuthAttributesWereFound_ButAuthMiddlewareNotInvoked()
+    {
+        // Arrange
+        var expected = "Endpoint Test contains authorization metadata, but a middleware was not found that supports authorization." +
+            Environment.NewLine +
+            "Configure your application startup by adding app.UseAuthorization() in the application startup code. " +
+            "If there are calls to app.UseRouting() and app.UseEndpoints(...), the call to app.UseAuthorization() must go between them.";
+        var httpContext = new DefaultHttpContext
+        {
+            RequestServices = new ServiceProvider()
+        };
+
+        RequestDelegate throwIfCalled = (c) =>
+        {
+            throw new InvalidTimeZoneException("Should not be called");
+        };
+
+        httpContext.SetEndpoint(new Endpoint(requestDelegate: null, new EndpointMetadataCollection(Mock.Of<IAuthorizeData>()), "Test"));
+
+        var middleware = new EndpointMiddleware(NullLogger<EndpointMiddleware>.Instance, throwIfCalled, RouteOptions);
+
+        // Act & Assert
+        var ex = await Assert.ThrowsAsync<InvalidOperationException>(() => middleware.Invoke(httpContext));
+
+        // Assert
+        Assert.Equal(expected, ex.Message);
+    }
+
     [Fact]
     public async Task Invoke_WithEndpoint_WorksIfAuthAttributesWereFound_AndAuthMiddlewareInvoked()
     {

src/Middleware/StaticFiles/src/DefaultFilesMiddleware.cs

@@ -59,7 +59,7 @@ public class DefaultFilesMiddleware
     /// <returns></returns>
     public Task Invoke(HttpContext context)
     {
-        if (context.GetEndpoint() == null
+        if (context.GetEndpoint()?.RequestDelegate is null
             && Helpers.IsGetOrHeadMethod(context.Request.Method)
             && Helpers.TryMatchPath(context, _matchUrl, forDirectory: true, subpath: out var subpath))
         {

src/Middleware/StaticFiles/src/DirectoryBrowserMiddleware.cs

@@ -75,8 +75,8 @@ public class DirectoryBrowserMiddleware
     /// <returns></returns>
     public Task Invoke(HttpContext context)
     {
-        // Check if the URL matches any expected paths, skip if an endpoint was selected
-        if (context.GetEndpoint() == null
+        // Check if the URL matches any expected paths, skip if an endpoint with a request delegate was selected
+        if (context.GetEndpoint()?.RequestDelegate is null
             && Helpers.IsGetOrHeadMethod(context.Request.Method)
             && Helpers.TryMatchPath(context, _matchUrl, forDirectory: true, subpath: out var subpath)
             && TryGetDirectoryInfo(subpath, out var contents))

src/Middleware/StaticFiles/src/StaticFileMiddleware.cs

@@ -66,7 +66,7 @@ public class StaticFileMiddleware
     /// <returns></returns>
     public Task Invoke(HttpContext context)
     {
-        if (!ValidateNoEndpoint(context))
+        if (!ValidateNoEndpointDelegate(context))
         {
             _logger.EndpointMatched();
         }
@@ -91,8 +91,8 @@ public class StaticFileMiddleware
         return _next(context);
     }
 
-    // Return true because we only want to run if there is no endpoint.
-    private static bool ValidateNoEndpoint(HttpContext context) => context.GetEndpoint() == null;
+    // Return true because we only want to run if there is no endpoint delegate.
+    private static bool ValidateNoEndpointDelegate(HttpContext context) => context.GetEndpoint()?.RequestDelegate is null;
 
     private static bool ValidateMethod(HttpContext context)
     {

src/Middleware/StaticFiles/test/UnitTests/DefaultFilesMiddlewareTests.cs

@@ -78,7 +78,7 @@ public class DefaultFilesMiddlewareTests
     }
 
     [Fact]
-    public async Task Endpoint_PassesThrough()
+    public async Task Endpoint_With_RequestDelegate_PassesThrough()
     {
         using (var fileProvider = new PhysicalFileProvider(Path.Combine(AppContext.BaseDirectory, ".")))
         {
@@ -107,6 +107,9 @@ public class DefaultFilesMiddlewareTests
                     });
 
                     app.UseEndpoints(endpoints => { });
+
+                    // Echo back the current request path value
+                    app.Run(context => context.Response.WriteAsync(context.Request.Path.Value));
                 },
                 services => { services.AddDirectoryBrowser(); services.AddRouting(); });
             using var server = host.GetTestServer();
@@ -117,6 +120,48 @@ public class DefaultFilesMiddlewareTests
         }
     }
 
+    [Fact]
+    public async Task Endpoint_With_Null_RequestDelegate_Does_Not_PassThrough()
+    {
+        using (var fileProvider = new PhysicalFileProvider(Path.Combine(AppContext.BaseDirectory, ".")))
+        {
+            using var host = await StaticFilesTestServer.Create(
+                app =>
+                {
+                    app.UseRouting();
+
+                    app.Use(next => context =>
+                    {
+                        // Assign an endpoint with a null RequestDelegate, the default files should still run
+                        context.SetEndpoint(new Endpoint(requestDelegate: null,
+                        new EndpointMetadataCollection(),
+                        "test"));
+
+                        return next(context);
+                    });
+
+                    app.UseDefaultFiles(new DefaultFilesOptions
+                    {
+                        RequestPath = new PathString(""),
+                        FileProvider = fileProvider
+                    });
+
+                    app.UseEndpoints(endpoints => { });
+
+                    // Echo back the current request path value
+                    app.Run(context => context.Response.WriteAsync(context.Request.Path.Value));
+                },
+                services => { services.AddDirectoryBrowser(); services.AddRouting(); });
+            using var server = host.GetTestServer();
+
+            var response = await server.CreateRequest("/SubFolder/").GetAsync();
+            var responseContent = await response.Content.ReadAsStringAsync();
+
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal("/SubFolder/default.html", responseContent); // Should be modified and be valid path to file
+        }
+    }
+
     [Theory]
     [InlineData("", @".", "/SubFolder/")]
     [InlineData("", @"./", "/SubFolder/")]

src/Middleware/StaticFiles/test/UnitTests/DirectoryBrowserMiddlewareTests.cs

@@ -95,7 +95,7 @@ public class DirectoryBrowserMiddlewareTests
     }
 
     [Fact]
-    public async Task Endpoint_PassesThrough()
+    public async Task Endpoint_With_RequestDelegate_PassesThrough()
     {
         using (var fileProvider = new PhysicalFileProvider(Path.Combine(AppContext.BaseDirectory, ".")))
         {
@@ -135,6 +135,45 @@ public class DirectoryBrowserMiddlewareTests
         }
     }
 
+    [Fact]
+    public async Task Endpoint_With_Null_RequestDelegate_Does_Not_PassThrough()
+    {
+        using (var fileProvider = new PhysicalFileProvider(Path.Combine(AppContext.BaseDirectory, ".")))
+        {
+            using var host = await StaticFilesTestServer.Create(
+                app =>
+                {
+                    app.UseRouting();
+
+                    app.Use(next => context =>
+                    {
+                        // Assign an endpoint with a null RequestDelegate, the directory browser should still run
+                        context.SetEndpoint(new Endpoint(requestDelegate: null,
+                        new EndpointMetadataCollection(),
+                        "test"));
+
+                        return next(context);
+                    });
+
+                    app.UseDirectoryBrowser(new DirectoryBrowserOptions
+                    {
+                        RequestPath = new PathString(""),
+                        FileProvider = fileProvider
+                    });
+
+                    app.UseEndpoints(endpoints => { });
+                },
+                services => { services.AddDirectoryBrowser(); services.AddRouting(); });
+            using var server = host.GetTestServer();
+
+            var response = await server.CreateRequest("/").GetAsync();
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal("text/html; charset=utf-8", response.Content.Headers.ContentType.ToString());
+            Assert.True(response.Content.Headers.ContentLength > 0);
+            Assert.Equal(response.Content.Headers.ContentLength, (await response.Content.ReadAsByteArrayAsync()).Length);
+        }
+    }
+
     [Theory]
     [InlineData("", @".", "/")]
     [InlineData("", @".", "/SubFolder/")]

src/Middleware/StaticFiles/test/UnitTests/StaticFileMiddlewareTests.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Globalization;
 using System.Net;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
@@ -9,6 +10,7 @@ using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.AspNetCore.Testing;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Hosting;
 using Moq;
@@ -193,6 +195,86 @@ public class StaticFileMiddlewareTests
         }
     }
 
+    [Fact]
+    public async Task File_Served_If_Endpoint_With_Null_RequestDelegate_Is_Active()
+    {
+        using (var fileProvider = new PhysicalFileProvider(Path.Combine(AppContext.BaseDirectory, ".")))
+        {
+            using var host = await StaticFilesTestServer.Create(app =>
+            {
+                app.UseRouting();
+                app.Use((ctx, next) =>
+                {
+                    ctx.SetEndpoint(new Endpoint(requestDelegate: null, new EndpointMetadataCollection(), "NullRequestDelegateEndpoint"));
+                    return next();
+                });
+                app.UseStaticFiles(new StaticFileOptions
+                {
+                    RequestPath = new PathString(),
+                    FileProvider = fileProvider
+                });
+                app.UseEndpoints(endpoints => { });
+            }, services => services.AddRouting());
+            using var server = host.GetTestServer();
+            var requestUrl = "/TestDocument.txt";
+            var fileInfo = fileProvider.GetFileInfo(Path.GetFileName(requestUrl));
+            var response = await server.CreateRequest(requestUrl).GetAsync();
+            var responseContent = await response.Content.ReadAsByteArrayAsync();
+
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal("text/plain", response.Content.Headers.ContentType.ToString());
+            Assert.True(response.Content.Headers.ContentLength == fileInfo.Length);
+            Assert.Equal(response.Content.Headers.ContentLength, responseContent.Length);
+            Assert.NotNull(response.Headers.ETag);
+
+            using (var stream = fileInfo.CreateReadStream())
+            {
+                var fileContents = new byte[stream.Length];
+                stream.Read(fileContents, 0, (int)stream.Length);
+                Assert.True(responseContent.SequenceEqual(fileContents));
+            }
+        }
+    }
+
+    [Fact]
+    public async Task File_NotServed_If_Endpoint_With_RequestDelegate_Is_Active()
+    {
+        var responseText = DateTime.UtcNow.Ticks.ToString(CultureInfo.InvariantCulture);
+        RequestDelegate handler = async (ctx) =>
+        {
+            ctx.Response.ContentType = "text/customfortest+plain";
+            await ctx.Response.WriteAsync(responseText);
+        };
+
+        using (var fileProvider = new PhysicalFileProvider(Path.Combine(AppContext.BaseDirectory, ".")))
+        {
+            using var host = await StaticFilesTestServer.Create(app =>
+            {
+                app.UseRouting();
+                app.Use((ctx, next) =>
+                {
+                    ctx.SetEndpoint(new Endpoint(handler, new EndpointMetadataCollection(), "RequestDelegateEndpoint"));
+                    return next();
+                });
+                app.UseStaticFiles(new StaticFileOptions
+                {
+                    RequestPath = new PathString(),
+                    FileProvider = fileProvider
+                });
+                app.UseEndpoints(endpoints => { });
+            }, services => services.AddRouting());
+            using var server = host.GetTestServer();
+            var requestUrl = "/TestDocument.txt";
+
+            var response = await server.CreateRequest(requestUrl).GetAsync();
+            var responseContent = await response.Content.ReadAsStringAsync();
+
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Equal("text/customfortest+plain", response.Content.Headers.ContentType.ToString());
+            Assert.Equal(responseText, responseContent);
+        }
+    }
+
     [Theory]
     [MemberData(nameof(ExistingFiles))]
     public async Task HeadFile_HeadersButNotBodyServed(string baseUrl, string baseDir, string requestUrl)