Specify Content-Length for buffered responses (#9699)

src/Http/WebUtilities/src/FileBufferingWriteStream.cs

@@ -69,7 +69,7 @@ namespace Microsoft.AspNetCore.WebUtilities
         public override bool CanWrite => true;
 
         /// <inheritdoc />
-        public override long Length => throw new NotSupportedException();
+        public override long Length => PagedByteBuffer.Length + (FileStream?.Length ?? 0);
 
         /// <inheritdoc />
         public override long Position
@@ -78,8 +78,6 @@ namespace Microsoft.AspNetCore.WebUtilities
             set => throw new NotSupportedException();
         }
 
-        internal long BufferedLength => PagedByteBuffer.Length + (FileStream?.Length ?? 0);
-
         internal PagedByteBuffer PagedByteBuffer { get; }
 
         internal FileStream FileStream { get; private set; }
@@ -103,7 +101,7 @@ namespace Microsoft.AspNetCore.WebUtilities
             ThrowArgumentException(buffer, offset, count);
             ThrowIfDisposed();
 
-            if (_bufferLimit.HasValue && _bufferLimit - BufferedLength < count)
+            if (_bufferLimit.HasValue && _bufferLimit - Length < count)
             {
                 Dispose();
                 throw new IOException("Buffer limit exceeded.");
@@ -136,7 +134,7 @@ namespace Microsoft.AspNetCore.WebUtilities
             ThrowArgumentException(buffer, offset, count);
             ThrowIfDisposed();
 
-            if (_bufferLimit.HasValue && _bufferLimit - BufferedLength < count)
+            if (_bufferLimit.HasValue && _bufferLimit - Length < count)
             {
                 Dispose();
                 throw new IOException("Buffer limit exceeded.");

src/Http/WebUtilities/test/FileBufferingWriteStreamTests.cs

@@ -31,6 +31,8 @@ namespace Microsoft.AspNetCore.WebUtilities
             bufferingStream.Write(input, 0, input.Length);
 
             // Assert
+            Assert.Equal(input.Length, bufferingStream.Length);
+
             // We should have written content to memory
             var pagedByteBuffer = bufferingStream.PagedByteBuffer;
             Assert.Equal(input, ReadBufferedContent(pagedByteBuffer));
@@ -53,6 +55,8 @@ namespace Microsoft.AspNetCore.WebUtilities
             var pageBuffer = bufferingStream.PagedByteBuffer;
             var fileStream = bufferingStream.FileStream;
 
+            Assert.Equal(input.Length, bufferingStream.Length);
+
             // File should have been created.
             Assert.Null(fileStream);
 
@@ -238,6 +242,8 @@ namespace Microsoft.AspNetCore.WebUtilities
             Assert.NotNull(fileStream);
             var fileBytes = ReadFileContent(fileStream);
 
+            Assert.Equal(input.Length, bufferingStream.Length);
+
             Assert.Equal(new byte[] { 1, 2, 3, 4, 5, }, fileBytes);
             Assert.Equal(new byte[] { 6, 7 }, ReadBufferedContent(pageBuffer));
         }
@@ -344,6 +350,7 @@ namespace Microsoft.AspNetCore.WebUtilities
 
             // Assert
             Assert.Equal(input, memoryStream.ToArray());
+            Assert.Equal(0, bufferingStream.Length);
         }
 
         [Fact]
@@ -360,6 +367,7 @@ namespace Microsoft.AspNetCore.WebUtilities
 
             // Assert
             Assert.Equal(input, memoryStream.ToArray());
+            Assert.Equal(0, bufferingStream.Length);
         }
 
         public void Dispose()

src/Mvc/Mvc.Formatters.Xml/src/XmlDataContractSerializerOutputFormatter.cs

@@ -101,7 +101,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
         public XmlWriterSettings WriterSettings { get; }
 
         /// <summary>
-        /// Gets or sets the <see cref="DataContractSerializerSettings"/> used to configure the 
+        /// Gets or sets the <see cref="DataContractSerializerSettings"/> used to configure the
         /// <see cref="DataContractSerializer"/>.
         /// </summary>
         public DataContractSerializerSettings SerializerSettings
@@ -284,6 +284,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
                 if (fileBufferingWriteStream != null)
                 {
+                    response.ContentLength = fileBufferingWriteStream.Length;
                     await fileBufferingWriteStream.DrainBufferAsync(response.Body);
                 }
             }

src/Mvc/Mvc.Formatters.Xml/src/XmlSerializerOutputFormatter.cs

@@ -260,6 +260,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
                 if (fileBufferingWriteStream != null)
                 {
+                    response.ContentLength = fileBufferingWriteStream.Length;
                     await fileBufferingWriteStream.DrainBufferAsync(response.Body);
                 }
             }

src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonOutputFormatter.cs

@@ -94,7 +94,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
         /// <summary>
         /// Called during serialization to create the <see cref="JsonSerializer"/>.The formatter context
-        /// that is passed gives an ability to create serializer specific to the context. 
+        /// that is passed gives an ability to create serializer specific to the context.
         /// </summary>
         /// <returns>The <see cref="JsonSerializer"/> used during serialization and deserialization.</returns>
         protected virtual JsonSerializer CreateJsonSerializer()
@@ -109,7 +109,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
         /// <summary>
         /// Called during serialization to create the <see cref="JsonSerializer"/>.The formatter context
-        /// that is passed gives an ability to create serializer specific to the context. 
+        /// that is passed gives an ability to create serializer specific to the context.
         /// </summary>
         /// <param name="context">A context object for <see cref="IOutputFormatter.WriteAsync(OutputFormatterWriteContext)"/>.</param>
         /// <returns>The <see cref="JsonSerializer"/> used during serialization and deserialization.</returns>
@@ -154,6 +154,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
                 if (fileBufferingWriteStream != null)
                 {
+                    response.ContentLength = fileBufferingWriteStream.Length;
                     await fileBufferingWriteStream.DrainBufferAsync(response.Body);
                 }
             }

src/Mvc/test/Mvc.FunctionalTests/NewtonsoftJsonOutputFormatterTest.cs

@@ -4,6 +4,7 @@
 using System.Net;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.NewtonsoftJson;
+using FormatterWebSite.Controllers;
 using Newtonsoft.Json;
 using Xunit;
 
@@ -41,5 +42,16 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             var actualBody = await response.Content.ReadAsStringAsync();
             Assert.Equal(expectedBody, actualBody);
         }
+
+        [Fact]
+        public async Task JsonOutputFormatter_SetsContentLength()
+        {
+            // Act
+            var response = await Client.GetAsync($"/JsonOutputFormatter/{nameof(JsonOutputFormatterController.SimpleModelResult)}");
+
+            // Assert
+            await response.AssertStatusCodeAsync(HttpStatusCode.OK);
+            Assert.Equal(50, response.Content.Headers.ContentLength);
+        }
     }
 }

src/Mvc/test/Mvc.FunctionalTests/XmlOutputFormatterTests.cs

@@ -41,6 +41,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
                 "xmlns=\"http://schemas.datacontract.org/2004/07/FormatterWebSite\">" +
                 "<SampleInt>10</SampleInt></DummyClass>",
                 await response.Content.ReadAsStringAsync());
+            Assert.Equal(167, response.Content.Headers.ContentLength);
         }
 
         [Fact]
@@ -61,6 +62,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
                 "<DummyClass xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" " +
                 "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"><SampleInt>10</SampleInt></DummyClass>",
                 await response.Content.ReadAsStringAsync());
+            Assert.Equal(149, response.Content.Headers.ContentLength);
         }
 
         [ConditionalFact]