Add option to remove the Server header

src/Microsoft.AspNetCore.Server.Kestrel/Http/Frame.cs

@@ -610,10 +610,15 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
                     var responseHeaders = _frameHeaders.ResponseHeaders;
                     responseHeaders.Reset();
                     var dateHeaderValues = DateHeaderValueManager.GetDateHeaderValues();
+
                     responseHeaders.SetRawDate(dateHeaderValues.String, dateHeaderValues.Bytes);
-                    responseHeaders.SetRawServer("Kestrel", Headers.BytesServer);
                     responseHeaders.SetRawContentLength("0", _bytesContentLengthZero);
 
+                    if (ServerOptions.AddServerHeader)
+                    {
+                        responseHeaders.SetRawServer(Constants.ServerName, Headers.BytesServer);
+                    }
+
                     ResponseHeaders = responseHeaders;
                 }
             }

src/Microsoft.AspNetCore.Server.Kestrel/Infrastructure/Constants.cs

@@ -23,6 +23,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Infrastructure
         /// </summary>
         public const string RFC1123DateFormat = "r";
 
+        public const string ServerName = "Kestrel";
+
         private static int? GetECONNRESET()
         {
             switch (PlatformServices.Default.Runtime.OperatingSystemPlatform)

src/Microsoft.AspNetCore.Server.Kestrel/Infrastructure/HttpComponentFactory.cs

@@ -50,7 +50,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Infrastructure
 
             if (!_headerPool.TryDequeue(out headers))
             {
-                headers = new Headers();
+                headers = new Headers(ServerOptions);
             }
 
             headers.Initialize(dateValueManager);
@@ -76,11 +76,23 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Infrastructure
         public readonly FrameRequestHeaders RequestHeaders = new FrameRequestHeaders();
         public readonly FrameResponseHeaders ResponseHeaders = new FrameResponseHeaders();
 
+        private readonly KestrelServerOptions _options;
+
+        public Headers(KestrelServerOptions options)
+        {
+            _options = options;
+        }
+
         public void Initialize(DateHeaderValueManager dateValueManager)
         {
             var dateHeaderValues = dateValueManager.GetDateHeaderValues();
+
             ResponseHeaders.SetRawDate(dateHeaderValues.String, dateHeaderValues.Bytes);
-            ResponseHeaders.SetRawServer("Kestrel", BytesServer);
+
+            if (_options.AddServerHeader)
+            {
+                ResponseHeaders.SetRawServer(Constants.ServerName, BytesServer);
+            }
         }
 
         public void Uninitialize()

src/Microsoft.AspNetCore.Server.Kestrel/KestrelServerOptions.cs

@@ -32,6 +32,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel
 
         public bool NoDelay { get; set; } = true;
 
+        /// <summary>
+        /// Gets or sets whether the <c>Server</c> header should be included in each response.
+        /// </summary>
+        public bool AddServerHeader { get; set; } = true;
+
         /// <summary>
         /// The amount of time after the server begins shutting down before connections will be forcefully closed.
         /// By default, Kestrel will wait 5 seconds for any ongoing requests to complete before terminating

test/Microsoft.AspNetCore.Server.KestrelTests/FrameResponseHeadersTests.cs

@@ -15,10 +15,13 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
 {
     public class FrameResponseHeadersTests
     {
-        [Fact]
-        public void InitialDictionaryContainsServerAndDate()
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void InitialDictionaryContainsServerAndDate(bool addServerHeader)
         {
-            var serverOptions = new KestrelServerOptions();
+            var serverOptions = new KestrelServerOptions { AddServerHeader = addServerHeader };
+
             var connectionContext = new ConnectionContext
             {
                 DateHeaderValueManager = new DateHeaderValueManager(),
@@ -31,12 +34,22 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
 
             IDictionary<string, StringValues> headers = frame.ResponseHeaders;
 
-            Assert.Equal(2, headers.Count);
+            if (addServerHeader)
+            {
+                Assert.Equal(2, headers.Count);
 
-            StringValues serverHeader;
-            Assert.True(headers.TryGetValue("Server", out serverHeader));
-            Assert.Equal(1, serverHeader.Count);
-            Assert.Equal("Kestrel", serverHeader[0]);
+                StringValues serverHeader;
+                Assert.True(headers.TryGetValue("Server", out serverHeader));
+                Assert.Equal(1, serverHeader.Count);
+                Assert.Equal("Kestrel", serverHeader[0]);
+            }
+            else
+            {
+                Assert.Equal(1, headers.Count);
+
+                StringValues serverHeader;
+                Assert.False(headers.TryGetValue("Server", out serverHeader));
+            }
 
             StringValues dateHeader;
             DateTime date;