Merged PR 9014: [2.1] Cancel SendFile copy loops

There are two places in 2.1 where SendFileAsync falls back to a copy loop. These loops should short circuit when the client disconnects, or else the server will sit there and burn resources reading the whole file from disk.

Fix: If you passed in your own active CT we'll use it. Otherwise we'll use the RequestAborted token.

eng/PatchConfig.props

@@ -68,6 +68,8 @@ Later on, this will be checked using this condition:
   </PropertyGroup>
   <PropertyGroup Condition=" '$(VersionPrefix)' == '2.1.21' ">
     <PackagesInPatch>
+      Microsoft.AspNetCore.Http.Extensions;
+      Microsoft.AspNetCore.ResponseCompression;
     </PackagesInPatch>
   </PropertyGroup>
 </Project>

src/Http/Http.Extensions/src/SendFileResponseExtensions.cs

@@ -107,41 +107,28 @@ namespace Microsoft.AspNetCore.Http
 
         private static async Task SendFileAsyncCore(HttpResponse response, IFileInfo file, long offset, long? count, CancellationToken cancellationToken)
         {
-            if (string.IsNullOrEmpty(file.PhysicalPath))
+            if (!string.IsNullOrEmpty(file.PhysicalPath))
-            {
-                CheckRange(offset, count, file.Length);
-
-                using (var fileContent = file.CreateReadStream())
-                {
-                    if (offset > 0)
-                    {
-                        fileContent.Seek(offset, SeekOrigin.Begin);
-                    }
-                    await StreamCopyOperation.CopyToAsync(fileContent, response.Body, count, cancellationToken);
-                }
-            }
-            else
             {
                 await response.SendFileAsync(file.PhysicalPath, offset, count, cancellationToken);
+                return;
+            }
+
+            CheckRange(offset, count, file.Length);
+            using (var fileContent = file.CreateReadStream())
+            {
+                await SendStreamAsync(fileContent, response, offset, count, cancellationToken);
             }
         }
 
-        private static Task SendFileAsyncCore(HttpResponse response, string fileName, long offset, long? count, CancellationToken cancellationToken = default)
+        private static async Task SendFileAsyncCore(HttpResponse response, string fileName, long offset, long? count, CancellationToken cancellationToken = default)
         {
             var sendFile = response.HttpContext.Features.Get<IHttpSendFileFeature>();
-            if (sendFile == null)
+            if (sendFile != null)
             {
-                return SendFileAsyncCore(response.Body, fileName, offset, count, cancellationToken);
+                await sendFile.SendFileAsync(fileName, offset, count, cancellationToken);
+                return;
             }
 
-            return sendFile.SendFileAsync(fileName, offset, count, cancellationToken);
-        }
-
-        // Not safe for overlapped writes.
-        private static async Task SendFileAsyncCore(Stream outputStream, string fileName, long offset, long? count, CancellationToken cancel = default)
-        {
-            cancel.ThrowIfCancellationRequested();
-
             var fileInfo = new FileInfo(fileName);
             CheckRange(offset, count, fileInfo.Length);
 
@@ -155,14 +142,44 @@ namespace Microsoft.AspNetCore.Http
                 options: FileOptions.Asynchronous | FileOptions.SequentialScan);
 
             using (fileStream)
+            {
+                await SendStreamAsync(fileStream, response, offset, count, cancellationToken);
+            }
+        }
+
+        private static Task SendStreamAsync(Stream source, HttpResponse response, long offset, long? count, CancellationToken cancellationToken)
+        {
+            if (!cancellationToken.CanBeCanceled)
+            {
+                return SendStreamQuietAsync(source, response, offset, count, response.HttpContext.RequestAborted);
+            }
+
+            cancellationToken.ThrowIfCancellationRequested();
+            if (offset > 0)
+            {
+                source.Seek(offset, SeekOrigin.Begin);
+            }
+
+            return StreamCopyOperation.CopyToAsync(source, response.Body, count, cancellationToken);
+        }
+
+        private static async Task SendStreamQuietAsync(Stream source, HttpResponse response, long offset, long? count, CancellationToken cancellationToken)
+        {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return;
+            }
+
+            try
             {
                 if (offset > 0)
                 {
-                    fileStream.Seek(offset, SeekOrigin.Begin);
+                    source.Seek(offset, SeekOrigin.Begin);
                 }
 
-                await StreamCopyOperation.CopyToAsync(fileStream, outputStream, count, cancel);
+                await StreamCopyOperation.CopyToAsync(source, response.Body, count, cancellationToken);
             }
+            catch (OperationCanceledException) { }
         }
 
         private static void CheckRange(long offset, long? count, long fileLength)
@@ -178,4 +195,4 @@ namespace Microsoft.AspNetCore.Http
             }
         }
     }
-}
+}

src/Http/Http.Extensions/test/Microsoft.AspNetCore.Http.Extensions.Tests.csproj

@@ -4,6 +4,10 @@
     <TargetFrameworks>netcoreapp2.1;net461</TargetFrameworks>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Content Include="testfile1kb.txt" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
   <ItemGroup>
     <Reference Include="Microsoft.AspNetCore.Http" />
     <Reference Include="Microsoft.AspNetCore.Http.Extensions" />

src/Http/Http.Extensions/test/SendFileResponseExtensionsTests.cs

@@ -1,5 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved. See License.txt in the project root for license information.
 
+using System;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
@@ -49,5 +50,46 @@ namespace Microsoft.AspNetCore.Http.Extensions.Tests
                 return Task.FromResult(0);
             }
         }
+
+        [Fact]
+        public async Task SendFile_FallsBackToBodyStream()
+        {
+            var body = new MemoryStream();
+            var context = new DefaultHttpContext();
+            var response = context.Response;
+            response.Body = body;
+
+            await response.SendFileAsync("testfile1kb.txt", 1, 3, CancellationToken.None);
+
+            Assert.Equal(3, body.Length);
+        }
+
+        [Fact]
+        public async Task SendFile_ThrowsWhenCanceled()
+        {
+            var body = new MemoryStream();
+            var context = new DefaultHttpContext();
+            var response = context.Response;
+            response.Body = body;
+
+            await Assert.ThrowsAsync<OperationCanceledException>(
+                () => response.SendFileAsync("testfile1kb.txt", 1, 3, new CancellationToken(canceled: true)));
+
+            Assert.Equal(0, body.Length);
+        }
+
+        [Fact]
+        public async Task SendFile_AbortsSilentlyWhenRequestCanceled()
+        {
+            var body = new MemoryStream();
+            var context = new DefaultHttpContext();
+            context.RequestAborted = new CancellationToken(canceled: true);
+            var response = context.Response;
+            response.Body = body;
+
+            await response.SendFileAsync("testfile1kb.txt", 1, 3, CancellationToken.None);
+
+            Assert.Equal(0, body.Length);
+        }
     }
 }

src/Http/Http.Extensions/test/testfile1kb.txt

@@ -0,0 +1 @@
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

src/Http/HttpAbstractions.sln

@@ -81,6 +81,10 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "RoutingSample.Web", "Routin
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "dependencies", "dependencies", "{793FFE24-138A-4C3D-81AB-18D625E36230}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.AspNetCore.Server.Kestrel", "..\Servers\Kestrel\Kestrel\src\Microsoft.AspNetCore.Server.Kestrel.csproj", "{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.AspNetCore.Server.IISIntegration", "..\Servers\IIS\IISIntegration\src\Microsoft.AspNetCore.Server.IISIntegration.csproj", "{11E37916-24DF-48A3-AFC9-9E9BB76588E4}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -403,6 +407,30 @@ Global
 		{F4F5D8AF-FBD1-463F-9473-B63AA820A6C4}.Release|x64.Build.0 = Release|Any CPU
 		{F4F5D8AF-FBD1-463F-9473-B63AA820A6C4}.Release|x86.ActiveCfg = Release|Any CPU
 		{F4F5D8AF-FBD1-463F-9473-B63AA820A6C4}.Release|x86.Build.0 = Release|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Debug|x64.Build.0 = Debug|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Debug|x86.Build.0 = Debug|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Release|x64.ActiveCfg = Release|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Release|x64.Build.0 = Release|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Release|x86.ActiveCfg = Release|Any CPU
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566}.Release|x86.Build.0 = Release|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Debug|x64.Build.0 = Debug|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Debug|x86.Build.0 = Debug|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Release|Any CPU.Build.0 = Release|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Release|x64.ActiveCfg = Release|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Release|x64.Build.0 = Release|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Release|x86.ActiveCfg = Release|Any CPU
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -435,6 +463,8 @@ Global
 		{E4AC79A3-625B-421B-9F91-EFCBD9BEB37F} = {24D19E8E-25FD-4C0B-8865-697878B67BE0}
 		{BF8DC0FF-96F9-4705-8CFA-F42BE989AB6A} = {793FFE24-138A-4C3D-81AB-18D625E36230}
 		{F4F5D8AF-FBD1-463F-9473-B63AA820A6C4} = {14A7B3DE-46C8-4245-B0BD-9AFF3795C163}
+		{C2608BEB-0C4C-4EDB-A0E4-E29AE59B4566} = {793FFE24-138A-4C3D-81AB-18D625E36230}
+		{11E37916-24DF-48A3-AFC9-9E9BB76588E4} = {793FFE24-138A-4C3D-81AB-18D625E36230}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {85B5E151-2E9D-419C-83DD-0DDCF446C83A}

src/Middleware/Middleware.sln

@@ -191,6 +191,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.AspNetCore.Server
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "_dependencies", "_dependencies", "{ACA6DDB9-7592-47CE-A740-D15BF307E9E0}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.AspNetCore.Server.IISIntegration", "..\Servers\IIS\IISIntegration\src\Microsoft.AspNetCore.Server.IISIntegration.csproj", "{F05215CF-F754-47BF-ACED-259C53C8B223}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -1005,6 +1007,18 @@ Global
 		{260E77CB-800F-4A13-BE92-9CAA097705C2}.Release|x64.Build.0 = Release|Any CPU
 		{260E77CB-800F-4A13-BE92-9CAA097705C2}.Release|x86.ActiveCfg = Release|Any CPU
 		{260E77CB-800F-4A13-BE92-9CAA097705C2}.Release|x86.Build.0 = Release|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Debug|x64.Build.0 = Debug|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Debug|x86.Build.0 = Debug|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Release|Any CPU.Build.0 = Release|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Release|x64.ActiveCfg = Release|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Release|x64.Build.0 = Release|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Release|x86.ActiveCfg = Release|Any CPU
+		{F05215CF-F754-47BF-ACED-259C53C8B223}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1086,6 +1100,7 @@ Global
 		{0186A5D0-6D05-4C19-BB81-E49A51745FFF} = {ACA6DDB9-7592-47CE-A740-D15BF307E9E0}
 		{17B7BFF6-4E72-410C-B690-02741505500A} = {ACA6DDB9-7592-47CE-A740-D15BF307E9E0}
 		{260E77CB-800F-4A13-BE92-9CAA097705C2} = {ACA6DDB9-7592-47CE-A740-D15BF307E9E0}
+		{F05215CF-F754-47BF-ACED-259C53C8B223} = {ACA6DDB9-7592-47CE-A740-D15BF307E9E0}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {83786312-A93B-4BB4-AB06-7C6913A59AFA}

src/Middleware/ResponseCompression/src/BodyWrapperStream.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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;
@@ -286,10 +286,8 @@ namespace Microsoft.AspNetCore.ResponseCompression
             return _innerSendFileFeature.SendFileAsync(path, offset, count, cancellation);
         }
 
-        private async Task InnerSendFileAsync(string path, long offset, long? count, CancellationToken cancellation)
+        private Task InnerSendFileAsync(string path, long offset, long? count, CancellationToken cancellation)
         {
-            cancellation.ThrowIfCancellationRequested();
-
             var fileInfo = new FileInfo(path);
             if (offset < 0 || offset > fileInfo.Length)
             {
@@ -311,9 +309,25 @@ namespace Microsoft.AspNetCore.ResponseCompression
                 bufferSize: bufferSize,
                 options: FileOptions.Asynchronous | FileOptions.SequentialScan);
 
+            if (cancellation.CanBeCanceled)
+            {
+                return InnerSendFileLoudAsync(fileStream, offset, count, cancellation);
+            }
+
+            return InnerSendFileQuietAsync(fileStream, offset, count, _context.RequestAborted);
+        }
+
+        private async Task InnerSendFileLoudAsync(Stream fileStream, long offset, long? count, CancellationToken cancellation)
+        {
             using (fileStream)
             {
-                fileStream.Seek(offset, SeekOrigin.Begin);
+                cancellation.ThrowIfCancellationRequested();
+
+                if (offset > 0)
+                {
+                    fileStream.Seek(offset, SeekOrigin.Begin);
+                }
+
                 await StreamCopyOperation.CopyToAsync(fileStream, _compressionStream, count, cancellation);
 
                 if (_autoFlush)
@@ -322,5 +336,31 @@ namespace Microsoft.AspNetCore.ResponseCompression
                 }
             }
         }
+
+        private async Task InnerSendFileQuietAsync(Stream fileStream, long offset, long? count, CancellationToken cancellation)
+        {
+            try
+            {
+                if (!cancellation.IsCancellationRequested)
+                {
+                    if (offset > 0)
+                    {
+                        fileStream.Seek(offset, SeekOrigin.Begin);
+                    }
+
+                    await StreamCopyOperation.CopyToAsync(fileStream, _compressionStream, count, cancellation);
+
+                    if (_autoFlush)
+                    {
+                        await _compressionStream.FlushAsync(cancellation);
+                    }
+                }
+            }
+            catch (OperationCanceledException) { }
+            finally
+            {
+                fileStream.Dispose();
+            }
+        }
     }
 }

src/Middleware/ResponseCompression/test/BodyWrapperStreamTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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;
@@ -90,6 +90,22 @@ namespace Microsoft.AspNetCore.ResponseCompression.Tests
             Assert.Equal(File.ReadAllBytes(path), memoryStream.ToArray());
         }
 
+        [Fact]
+        public async Task SendFileAsync_SkipsSilently_WhenRequestAborted()
+        {
+            var memoryStream = new MemoryStream();
+
+            var context = new DefaultHttpContext();
+            context.RequestAborted = new CancellationToken(canceled: true);
+            var stream = new BodyWrapperStream(context, memoryStream, new MockResponseCompressionProvider(true), null, null);
+
+            var path = "testfile1kb.txt";
+            await stream.SendFileAsync(path, 0, null, CancellationToken.None);
+            stream.Flush();
+
+            Assert.Equal(0, memoryStream.Length);
+        }
+
         [Theory]
         [InlineData(true)]
         [InlineData(false)]