IISHttpContext.FeatureCollection.Protocol recognizes HTTP/2 (#14412)

Author: gfoidl

src/Servers/HttpSys/src/FeatureContext.cs

@@ -174,23 +174,7 @@ string IHttpRequestFeature.Protocol
             {
                 if (IsNotInitialized(Fields.Protocol))
                 {
-                    var protocol = Request.ProtocolVersion;
-                    if (protocol == Constants.V2)
-                    {
-                        _httpProtocolVersion = "HTTP/2";
-                    }
-                    else if (protocol == Constants.V1_1)
-                    {
-                        _httpProtocolVersion = "HTTP/1.1";
-                    }
-                    else if (protocol == Constants.V1_0)
-                    {
-                        _httpProtocolVersion = "HTTP/1.0";
-                    }
-                    else
-                    {
-                        _httpProtocolVersion = "HTTP/" + protocol.ToString(2);
-                    }
+                    _httpProtocolVersion = Request.ProtocolVersion.GetHttpProtocolVersion();
                     SetInitialized(Fields.Protocol);
                 }
                 return _httpProtocolVersion;

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

@@ -15,6 +15,7 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Http.Features.Authentication;
+using Microsoft.AspNetCore.HttpSys.Internal;
 using Microsoft.AspNetCore.Server.IIS.Core.IO;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.Logging;
@@ -37,7 +38,7 @@ internal partial class IISHttpContext : IFeatureCollection,
         // then the list of `implementedFeatures` in the generated code project MUST also be updated.
 
         private int _featureRevision;
-        private string _httpProtocolVersion = null;
+        private string _httpProtocolVersion;
         private X509Certificate2 _certificate;
 
         private List<KeyValuePair<Type, object>> MaybeExtra;
@@ -86,30 +87,8 @@ private void ExtraFeatureSet(Type key, object value)
 
         string IHttpRequestFeature.Protocol
         {
-            get
-            {
-                if (_httpProtocolVersion == null)
-                {
-                    var protocol = HttpVersion;
-                    if (protocol.Major == 1 && protocol.Minor == 1)
-                    {
-                        _httpProtocolVersion = "HTTP/1.1";
-                    }
-                    else if (protocol.Major == 1 && protocol.Minor == 0)
-                    {
-                        _httpProtocolVersion = "HTTP/1.0";
-                    }
-                    else
-                    {
-                        _httpProtocolVersion = "HTTP/" + protocol.ToString(2);
-                    }
-                }
-                return _httpProtocolVersion;
-            }
-            set
-            {
-                _httpProtocolVersion = value;
-            }
+            get => _httpProtocolVersion ??= HttpVersion.GetHttpProtocolVersion();
+            set => _httpProtocolVersion = value;
         }
 
         string IHttpRequestFeature.Scheme

src/Shared/HttpSys/Constants.cs

@@ -15,8 +15,8 @@ internal static class Constants
         internal const string SchemeDelimiter = "://";
         internal const string DefaultServerAddress = "http://localhost:5000";
 
-        internal static Version V1_0 = new Version(1, 0);
-        internal static Version V1_1 = new Version(1, 1);
-        internal static Version V2 = new Version(2, 0);
+        internal static readonly Version V1_0 = new Version(1, 0);
+        internal static readonly Version V1_1 = new Version(1, 1);
+        internal static readonly Version V2 = new Version(2, 0);
     }
 }

src/Shared/HttpSys/Extensions.cs

@@ -0,0 +1,18 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.HttpSys.Internal
+{
+    internal static class Extensions
+    {
+        public static string GetHttpProtocolVersion(this Version version) => version switch
+        {
+            { Major: 2, Minor: 0 } => "HTTP/2",
+            { Major: 1, Minor: 1 } => "HTTP/1.1",
+            { Major: 1, Minor: 0 } => "HTTP/1.0",
+            _ => "HTTP/" + version.ToString(2)
+        };
+    }
+}