HTTP/3: Update alt-svc value to h3-29 and add unit test (#28772)

Author: JamesNK

src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.cs

@@ -1187,13 +1187,16 @@ private HttpResponseHeaders CreateResponseHeaders(bool appCompleted)
             }
 
             // TODO allow customization of this.
+            // Chrome is using h3-29 for protocol ID as of 12/2020. This is likely to be the alt-svc
+            // value until HTTP/3 is finalized.
+            // More info: https://blog.chromium.org/2020/10/chrome-is-deploying-http3-and-ietf-quic.html
             if (ServerOptions.EnableAltSvc && _httpVersion < Http.HttpVersion.Http3)
             {
                 foreach (var option in ServerOptions.ListenOptions)
                 {
                     if ((option.Protocols & HttpProtocols.Http3) == HttpProtocols.Http3)
                     {
-                        responseHeaders.HeaderAltSvc = $"h3-25=\":{option.IPEndPoint!.Port}\"; ma=84600";
+                        responseHeaders.HeaderAltSvc = $"h3-29=\":{option.IPEndPoint!.Port}\"; ma=84600";
                         break;
                     }
                 }

src/Servers/Kestrel/Core/src/KestrelServerOptions.cs

@@ -76,7 +76,7 @@ public class KestrelServerOptions
         public bool DisableStringReuse { get; set; } = false;
 
         /// <summary>
-        /// Controls whether to return the AltSvcHeader from on an HTTP/2 or lower response for HTTP/3
+        /// Controls whether to return the "Alt-Svc" header from an HTTP/2 or lower response for HTTP/3.
         /// </summary>
         /// <remarks>
         /// Defaults to false.

src/Servers/Kestrel/Transport.Quic/src/QuicConnectionFactory.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Transport.Experimental.Quic
 {
     internal class QuicConnectionFactory : IMultiplexedConnectionFactory
     {
-        private QuicTransportContext _transportContext;
+        private readonly QuicTransportContext _transportContext;
 
         public QuicConnectionFactory(IOptions<QuicTransportOptions> options, ILoggerFactory loggerFactory)
         {

src/Servers/Kestrel/test/InMemory.FunctionalTests/ResponseTests.cs

@@ -12,6 +12,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
+using Microsoft.AspNetCore.Connections.Experimental;
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
@@ -4076,6 +4077,41 @@ await connection.Receive(
             }
         }
 
+        [Theory]
+        [InlineData(HttpProtocols.Http1AndHttp2AndHttp3)]
+        [InlineData(HttpProtocols.Http3)]
+        public async Task EnableAltSvc_Http3EndpointConfigured_AltSvcInResponseHeaders(HttpProtocols protocols)
+        {
+            await using (var server = new TestServer(
+                context => Task.CompletedTask,
+                new TestServiceContext(),
+                options =>
+                {
+                    options.EnableAltSvc = true;
+                    options.CodeBackedListenOptions.Add(new ListenOptions(new IPEndPoint(IPAddress.Loopback, 0)));
+                    options.CodeBackedListenOptions.Add(new ListenOptions(new IPEndPoint(IPAddress.Loopback, 1)) { Protocols = protocols });
+                },
+                services => { }))
+            {
+                using (var connection = server.CreateConnection())
+                {
+                    await connection.Send(
+                        "GET / HTTP/1.1",
+                        "Host:",
+                        "",
+                        "");
+
+                    await connection.Receive(
+                        $"HTTP/1.1 200 OK",
+                        $"Date: {server.Context.DateHeaderValue}",
+                        "Content-Length: 0",
+                        @"Alt-Svc: h3-29="":1""; ma=84600",
+                        "",
+                        "");
+                }
+            }
+        }
+
         private static async Task ResponseStatusCodeSetBeforeHttpContextDispose(
             ITestSink testSink,
             ILoggerFactory loggerFactory,

src/Servers/Kestrel/test/InMemory.FunctionalTests/TestTransport/TestServer.cs

@@ -11,9 +11,11 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Connections;
+using Microsoft.AspNetCore.Connections.Experimental;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Server.Kestrel.Core;
 using Microsoft.AspNetCore.Testing;
 using Microsoft.Extensions.DependencyInjection;
@@ -89,7 +91,12 @@ public TestServer(RequestDelegate app, TestServiceContext context, Action<Kestre
                     {
                         context.ServerOptions.ApplicationServices = sp;
                         configureKestrel(context.ServerOptions);
-                        return new KestrelServerImpl(_transportFactory, context);
+                        return new KestrelServerImpl(
+                            new IConnectionListenerFactory[] { _transportFactory },
+                            // Mock multiplexed connection listner is added so Kestrel doesn't error
+                            // when a HTTP/3 endpoint is configured.
+                            new IMultiplexedConnectionListenerFactory[] { new MockMultiplexedConnectionListenerFactory() },
+                            context);
                     });
                 });
 
@@ -133,5 +140,38 @@ public async ValueTask DisposeAsync()
             await ((IAsyncDisposable)_host).DisposeAsync().ConfigureAwait(false);
             _memoryPool.Dispose();
         }
+
+        private class MockMultiplexedConnectionListenerFactory : IMultiplexedConnectionListenerFactory
+        {
+            public ValueTask<IMultiplexedConnectionListener> BindAsync(EndPoint endpoint, IFeatureCollection features = null, CancellationToken cancellationToken = default)
+            {
+                return ValueTask.FromResult<IMultiplexedConnectionListener>(new MockMultiplexedConnectionListener(endpoint));
+            }
+        }
+
+        private class MockMultiplexedConnectionListener : IMultiplexedConnectionListener
+        {
+            public MockMultiplexedConnectionListener(EndPoint endpoint)
+            {
+                EndPoint = endpoint;
+            }
+
+            public EndPoint EndPoint { get; }
+
+            public ValueTask<MultiplexedConnectionContext> AcceptAsync(IFeatureCollection features = null, CancellationToken cancellationToken = default)
+            {
+                return ValueTask.FromResult<MultiplexedConnectionContext>(null);
+            }
+
+            public ValueTask DisposeAsync()
+            {
+                return default;
+            }
+
+            public ValueTask UnbindAsync(CancellationToken cancellationToken = default)
+            {
+                return default;
+            }
+        }
     }
 }