Ignore null valued headers #429

Author: JunTaoLuo

src/Microsoft.AspNet.Server.Kestrel/Http/FrameResponseHeaders.cs

@@ -39,10 +39,13 @@ public void CopyTo(ref MemoryPoolIterator2 output)
                 {
                     foreach (var value in kv.Value)
                     {
-                        output.CopyFrom(_CrLf, 0, 2);
-                        output.CopyFromAscii(kv.Key);
-                        output.CopyFrom(_colonSpace, 0, 2);
-                        output.CopyFromAscii(value);
+                        if (value != null)
+                        {
+                            output.CopyFrom(_CrLf, 0, 2);
+                            output.CopyFromAscii(kv.Key);
+                            output.CopyFrom(_colonSpace, 0, 2);
+                            output.CopyFromAscii(value);
+                        }
                     }
                 }
             }

test/Microsoft.AspNet.Server.Kestrel.FunctionalTests/ResponseTests.cs

@@ -2,10 +2,12 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.Linq;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Builder;
 using Microsoft.AspNet.Hosting;
+using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Testing.xunit;
 using Microsoft.Extensions.Configuration;
 using Xunit;
@@ -44,7 +46,7 @@ public async Task LargeDownload()
                         await context.Response.Body.WriteAsync(bytes, 0, bytes.Length);
                     }
                 });
-            });            
+            });
 
             using (var app = hostBuilder.Build().Start())
             {
@@ -70,5 +72,53 @@ public async Task LargeDownload()
                 }
             }
         }
+
+        [ConditionalFact]
+        [FrameworkSkipCondition(RuntimeFrameworks.Mono, SkipReason = "Test hangs after execution on mono.")]
+        public async Task IgnoreNullHeaderValues()
+        {
+            var config = new ConfigurationBuilder()
+                .AddInMemoryCollection(new Dictionary<string, string>
+                {
+                    { "server.urls", "http://localhost:8793/" }
+                })
+                .Build();
+
+            var hostBuilder = new WebHostBuilder(config)
+                .UseServerFactory("Microsoft.AspNet.Server.Kestrel")
+                .UseStartup(app =>
+                {
+                    app.Run(async context =>
+                    {
+                        context.Response.Headers.Add("NullString", (string)null);
+                        context.Response.Headers.Add("EmptyString", "");
+                        context.Response.Headers.Add("NullStringArray", new string[] { null });
+                        context.Response.Headers.Add("EmptyStringArray", new string[] { "" });
+                        context.Response.Headers.Add("MixedStringArray", new string[] { null, "" });
+
+                        context.Response.ContentLength = 0;
+                        await context.Response.WriteAsync("");
+                    });
+                });
+
+            using (var app = hostBuilder.Build().Start())
+            {
+                using (var client = new HttpClient())
+                {
+                    var response = await client.GetAsync("http://localhost:8793/");
+                    response.EnsureSuccessStatusCode();
+
+                    var headers = response.Headers;
+                    Assert.False(headers.Contains("NullString"));
+                    Assert.True(headers.Contains("EmptyString"));
+                    Assert.Equal(headers.GetValues("EmptyString").Single(), "" );
+                    Assert.False(headers.Contains("NullStringArray"));
+                    Assert.True(headers.Contains("EmptyStringArray"));
+                    Assert.Equal(headers.GetValues("EmptyStringArray").Single(), "");
+                    Assert.True(headers.Contains("MixedStringArray"));
+                    Assert.Equal(headers.GetValues("MixedStringArray").Single(), "");
+                }
+            }
+        }
     }
 }