#366 Add flag to disable synchronous IO

src/Microsoft.AspNetCore.Server.HttpSys/FeatureContext.cs

@@ -29,7 +29,8 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         IHttpAuthenticationFeature,
         IHttpUpgradeFeature,
         IHttpRequestIdentifierFeature,
-        IHttpMaxRequestBodySizeFeature
+        IHttpMaxRequestBodySizeFeature,
+        IHttpBodyControlFeature
     {
         private RequestContext _requestContext;
         private IFeatureCollection _features;
@@ -464,6 +465,12 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             }
         }
 
+        bool IHttpBodyControlFeature.AllowSynchronousIO
+        {
+            get => _requestContext.AllowSynchronousIO;
+            set => _requestContext.AllowSynchronousIO = value;
+        }
+
         bool IHttpMaxRequestBodySizeFeature.IsReadOnly => Request.HasRequestBodyStarted;
 
         long? IHttpMaxRequestBodySizeFeature.MaxRequestBodySize

src/Microsoft.AspNetCore.Server.HttpSys/HttpSysOptions.cs

@@ -131,6 +131,12 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             }
         }
 
+        /// <summary>
+        /// Gets or sets a value that controls whether synchronous IO is allowed for the HttpContext.Request.Body and HttpContext.Response.Body.
+        /// The default is `true`.
+        /// </summary>
+        public bool AllowSynchronousIO { get; set; } = true;
+
         internal void Apply(UrlGroup urlGroup, RequestQueue requestQueue)
         {
             _urlGroup = urlGroup;

src/Microsoft.AspNetCore.Server.HttpSys/RequestProcessing/Request.cs

@@ -23,6 +23,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         // private byte[] _referredTokenBindingId;
 
         private BoundaryType _contentBoundaryType;
+
         private long? _contentLength;
         private RequestStream _nativeStream;
 
@@ -149,10 +150,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         {
             if (_nativeStream == null && HasEntityBody)
             {
-                _nativeStream = new RequestStream(RequestContext)
+                _nativeStream = new RequestStream(RequestContext);
-                {
-                    MaxSize = RequestContext.Server.Options.MaxRequestBodySize
-                };
             }
             return _nativeStream;
         }

src/Microsoft.AspNetCore.Server.HttpSys/RequestProcessing/RequestContext.cs

@@ -30,6 +30,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             _memoryBlob = memoryBlob;
             Request = new Request(this, _memoryBlob);
             Response = new Response(this);
+            AllowSynchronousIO = server.Options.AllowSynchronousIO;
         }
 
         internal HttpSysListener Server { get; }
@@ -88,6 +89,8 @@ namespace Microsoft.AspNetCore.Server.HttpSys
 
         public bool IsUpgradableRequest => Request.IsUpgradable;
 
+        internal bool AllowSynchronousIO { get; set; }
+
         public Task<Stream> UpgradeAsync()
         {
             if (!IsUpgradableRequest)

src/Microsoft.AspNetCore.Server.HttpSys/RequestProcessing/RequestStream.cs

@@ -25,6 +25,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         internal RequestStream(RequestContext httpContext)
         {
             _requestContext = httpContext;
+            _maxSize = _requestContext.Server.Options.MaxRequestBodySize;
         }
 
         internal RequestContext RequestContext
@@ -111,6 +112,11 @@ namespace Microsoft.AspNetCore.Server.HttpSys
 
         public override unsafe int Read([In, Out] byte[] buffer, int offset, int size)
         {
+            if (!RequestContext.AllowSynchronousIO)
+            {
+                throw new InvalidOperationException("Synchronous IO APIs are disabled, see AllowSynchronousIO.");
+            }
+
             ValidateReadBuffer(buffer, offset, size);
             CheckSizeLimit();
             if (_closed)

src/Microsoft.AspNetCore.Server.HttpSys/RequestProcessing/ResponseBody.cs

@@ -91,10 +91,16 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         // Send headers
         public override void Flush()
         {
+            if (!RequestContext.AllowSynchronousIO)
+            {
+                throw new InvalidOperationException("Synchronous IO APIs are disabled, see AllowSynchronousIO.");
+            }
+
             if (_disposed)
             {
                 return;
             }
+
             FlushInternal(endOfRequest: false);
         }
 
@@ -449,9 +455,15 @@ namespace Microsoft.AspNetCore.Server.HttpSys
 
         public override void Write(byte[] buffer, int offset, int count)
         {
+            if (!RequestContext.AllowSynchronousIO)
+            {
+                throw new InvalidOperationException("Synchronous IO APIs are disabled, see AllowSynchronousIO.");
+            }
+
             // Validates for null and bounds. Allows count == 0.
             // TODO: Verbose log parameters
             var data = new ArraySegment<byte>(buffer, offset, count);
+
             CheckDisposed();
 
             CheckWriteCount(count);

src/Microsoft.AspNetCore.Server.HttpSys/StandardFeatureCollection.cs

@@ -27,6 +27,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             { typeof(IHttpRequestIdentifierFeature), _identityFunc },
             { typeof(RequestContext), ctx => ctx.RequestContext },
             { typeof(IHttpMaxRequestBodySizeFeature), _identityFunc },
+            { typeof(IHttpBodyControlFeature), _identityFunc },
         };
 
         private readonly FeatureContext _featureContext;

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/HttpsTests.cs

@@ -60,10 +60,9 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 string input = new StreamReader(context.Request.Body).ReadToEnd();
                 Assert.Equal("Hello World", input);
                 context.Response.ContentLength = 11;
-                using (var writer = new StreamWriter(context.Response.Body))
+                var writer = new StreamWriter(context.Response.Body);
-                {
+                await writer.WriteAsync("Hello World");
-                    writer.Write("Hello World");
+                await writer.FlushAsync();
-                }
 
                 string response = await responseTask;
                 Assert.Equal("Hello World", response);

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/OpaqueUpgradeTests.cs

@@ -25,7 +25,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
 
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 byte[] body = Encoding.UTF8.GetBytes("Hello World");
-                context.Response.Body.Write(body, 0, body.Length);
+                await context.Response.Body.WriteAsync(body, 0, body.Length);
 
                 Assert.Throws<InvalidOperationException>(() => context.Response.Headers["Upgrade"] = "WebSocket"); // Win8.1 blocks anything but WebSocket
                 await Assert.ThrowsAsync<InvalidOperationException>(async () => await context.UpgradeAsync());

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/RequestBodyTests.cs

@@ -16,6 +16,32 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
 {
     public class RequestBodyTests
     {
+        [ConditionalFact]
+        public async Task RequestBody_SyncReadEnabledByDefault_ThrowsWhenDisabled()
+        {
+            string address;
+            using (var server = Utilities.CreateHttpServer(out address))
+            {
+                Task<string> responseTask = SendRequestAsync(address, "Hello World");
+
+                Assert.True(server.Options.AllowSynchronousIO);
+
+                var context = await server.AcceptAsync(Utilities.DefaultTimeout);
+                byte[] input = new byte[100];
+
+                Assert.True(context.AllowSynchronousIO);
+                var read = context.Request.Body.Read(input, 0, input.Length);
+                context.Response.ContentLength = read;
+                context.Response.Body.Write(input, 0, read);
+
+                context.AllowSynchronousIO = false;
+                Assert.Throws<InvalidOperationException>(() => context.Request.Body.Read(input, 0, input.Length));
+
+                string response = await responseTask;
+                Assert.Equal("Hello World", response);
+            }
+        }
+
         [ConditionalFact]
         public async Task RequestBody_ReadSync_Success()
         {
@@ -24,6 +50,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 Task<string> responseTask = SendRequestAsync(address, "Hello World");
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 byte[] input = new byte[100];
                 int read = context.Request.Body.Read(input, 0, input.Length);
@@ -81,6 +108,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 Task<string> responseTask = SendRequestAsync(address, "Hello World");
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 byte[] input = new byte[100];
                 Assert.Throws<ArgumentNullException>("buffer", () => context.Request.Body.Read(null, 0, 1));
@@ -106,6 +134,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 Task<string> responseTask = SendRequestAsync(address, content);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 byte[] input = new byte[10];
                 int read = context.Request.Body.Read(input, 0, input.Length);

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/ResponseBodyTests.cs

@@ -16,6 +16,41 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
 {
     public class ResponseBodyTests
     {
+        [ConditionalFact]
+        public async Task ResponseBody_SyncWriteEnabledByDefault_ThrowsWhenDisabled()
+        {
+            string address;
+            using (var server = Utilities.CreateHttpServer(out address))
+            {
+                var responseTask = SendRequestAsync(address);
+
+                var context = await server.AcceptAsync(Utilities.DefaultTimeout);
+
+                Assert.True(context.AllowSynchronousIO);
+
+                context.Response.Body.Flush();
+                context.Response.Body.Write(new byte[10], 0, 10);
+                context.Response.Body.Flush();
+
+                context.AllowSynchronousIO = false;
+
+                Assert.Throws<InvalidOperationException>(() => context.Response.Body.Flush());
+                Assert.Throws<InvalidOperationException>(() => context.Response.Body.Write(new byte[10], 0, 10));
+                Assert.Throws<InvalidOperationException>(() => context.Response.Body.Flush());
+
+                await context.Response.Body.WriteAsync(new byte[10], 0, 10);
+                context.Dispose();
+
+                var response = await responseTask;
+                Assert.Equal(200, (int)response.StatusCode);
+                Assert.Equal(new Version(1, 1), response.Version);
+                IEnumerable<string> ignored;
+                Assert.False(response.Content.Headers.TryGetValues("content-length", out ignored), "Content-Length");
+                Assert.True(response.Headers.TransferEncodingChunked.Value, "Chunked");
+                Assert.Equal(new byte[20], await response.Content.ReadAsByteArrayAsync());
+            }
+        }
+
         [ConditionalFact]
         public async Task ResponseBody_WriteNoHeaders_DefaultsToChunked()
         {
@@ -24,6 +59,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 var responseTask = SendRequestAsync(address);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 context.Response.Body.Write(new byte[10], 0, 10);
                 await context.Response.Body.WriteAsync(new byte[10], 0, 10);
@@ -45,6 +81,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             string address;
             using (var server = Utilities.CreateHttpServer(out address))
             {
+                server.Options.AllowSynchronousIO = true;
                 var responseTask = SendRequestAsync(address);
 
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
@@ -95,6 +132,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 var responseTask = SendRequestAsync(address);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 context.Response.Headers["Content-lenGth"] = " 30 ";
                 var stream = context.Response.Body;
@@ -181,6 +219,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 var responseTask = SendRequestAsync(address);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 context.Response.Headers["Content-lenGth"] = " 10 ";
                 context.Response.Body.Write(new byte[10], 0, 10);
@@ -206,6 +245,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 var responseTask = SendRequestAsync(address);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 context.Response.Body.Write(new byte[10], 0, 0);
                 Assert.True(context.Response.HasStarted);
@@ -380,6 +420,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             using (var server = Utilities.CreateHttpServer(out address))
             {
                 server.Options.ThrowWriteExceptions = true;
+                server.Options.AllowSynchronousIO = true;
                 var cts = new CancellationTokenSource();
                 var responseTask = SendRequestAsync(address, cts.Token);
 
@@ -444,6 +485,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 var cts = new CancellationTokenSource();
                 var responseTask = SendRequestAsync(address, cts.Token);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 // First write sends headers
                 cts.Cancel();
@@ -555,6 +597,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             string address;
             using (var server = Utilities.CreateHttpServer(out address))
             {
+                server.Options.AllowSynchronousIO = true;
                 RequestContext context;
                 using (var client = new HttpClient())
                 {

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/ResponseCachingTests.cs

@@ -324,7 +324,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["content-type"] = "some/thing"; // Http.sys requires a content-type to cache
                 context.Response.ContentLength = 10;
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[10], 0, 10);
+                await context.Response.Body.WriteAsync(new byte[10], 0, 10);
                 // Http.Sys will add this for us
                 Assert.Null(context.Response.ContentLength);
                 context.Dispose();
@@ -381,6 +381,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 var responseTask = SendRequestAsync(address);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 context.Response.Headers["x-request-count"] = "1";
                 context.Response.Headers["content-type"] = "some/thing"; // Http.sys requires a content-type to cache
@@ -418,8 +419,8 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["x-request-count"] = "1";
                 context.Response.Headers["content-type"] = "some/thing"; // Http.sys requires a content-type to cache
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[10], 0, 10);
+                await context.Response.Body.WriteAsync(new byte[10], 0, 10);
-                context.Response.Body.Flush();
+                await context.Response.Body.FlushAsync();
                 context.Dispose();
 
                 var response = await responseTask;
@@ -453,7 +454,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["content-type"] = "some/thing"; // Http.sys requires a content-type to cache
                 context.Response.ContentLength = 10;
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[10], 0, 10);
+                await context.Response.Body.WriteAsync(new byte[10], 0, 10);
                 // Http.Sys will add this for us
                 Assert.Null(context.Response.ContentLength);
                 context.Dispose();
@@ -999,7 +1000,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["content-range"] = "bytes 0-10/100";
                 context.Response.ContentLength = 11;
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[100], 0, 11);
+                await context.Response.Body.WriteAsync(new byte[100], 0, 11);
                 context.Dispose();
 
                 var response = await responseTask;
@@ -1016,7 +1017,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["content-range"] = "bytes 0-10/100";
                 context.Response.ContentLength = 11;
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[100], 0, 11);
+                await context.Response.Body.WriteAsync(new byte[100], 0, 11);
                 context.Dispose();
 
                 response = await responseTask;
@@ -1041,7 +1042,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["content-type"] = "some/thing"; // Http.sys requires a content-type to cache
                 context.Response.ContentLength = 100;
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[100], 0, 100);
+                await context.Response.Body.WriteAsync(new byte[100], 0, 100);
                 context.Dispose();
 
                 var response = await responseTask;
@@ -1071,7 +1072,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["content-type"] = "some/thing"; // Http.sys requires a content-type to cache
                 context.Response.ContentLength = 100;
                 context.Response.CacheTtl = TimeSpan.FromSeconds(10);
-                context.Response.Body.Write(new byte[100], 0, 100);
+                await context.Response.Body.WriteAsync(new byte[100], 0, 100);
                 context.Dispose();
 
                 var response = await responseTask;

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/ResponseHeaderTests.cs

@@ -390,6 +390,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
             {
                 Task<HttpResponseMessage> responseTask = SendRequestAsync(address);
 
+                server.Options.AllowSynchronousIO = true;
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 var responseHeaders = context.Response.Headers;
 

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/Listener/ServerTests.cs

@@ -42,10 +42,9 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
                 context.Response.ContentLength = 11;
-                using (var writer = new StreamWriter(context.Response.Body))
+                var writer = new StreamWriter(context.Response.Body);
-                {
+                await writer.WriteAsync("Hello World");
-                    writer.Write("Hello World");
+                await writer.FlushAsync();
-                }
 
                 string response = await responseTask;
                 Assert.Equal("Hello World", response);
@@ -61,13 +60,12 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 var responseTask = SendRequestAsync(address, "Hello World");
 
                 var context = await server.AcceptAsync(Utilities.DefaultTimeout);
-                string input = new StreamReader(context.Request.Body).ReadToEnd();
+                var input = await new StreamReader(context.Request.Body).ReadToEndAsync();
                 Assert.Equal("Hello World", input);
                 context.Response.ContentLength = 11;
-                using (var writer = new StreamWriter(context.Response.Body))
+                var writer = new StreamWriter(context.Response.Body);
-                {
+                await writer.WriteAsync("Hello World");
-                    writer.Write("Hello World");
+                await writer.FlushAsync();
-                }
 
                 var response = await responseTask;
                 Assert.Equal("Hello World", response);
@@ -218,10 +216,9 @@ namespace Microsoft.AspNetCore.Server.HttpSys.Listener
                 context.Response.Headers["Connection"] = "close";
 
                 context.Response.ContentLength = 11;
-                using (var writer = new StreamWriter(context.Response.Body))
+                var writer = new StreamWriter(context.Response.Body);
-                {
+                await writer.WriteAsync("Hello World");
-                    writer.Write("Hello World");
+                await writer.FlushAsync();
-                }
 
                 Assert.True(canceled.WaitOne(interval), "Disconnected");
                 Assert.True(ct.IsCancellationRequested, "IsCancellationRequested");

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/OpaqueUpgradeTests.cs

@@ -123,7 +123,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
                 Assert.True(feature.IsReadOnly);
                 Assert.Null(feature.MaxRequestBodySize);
                 Assert.Throws<InvalidOperationException>(() => feature.MaxRequestBodySize = 12);
-                Assert.Equal(15, stream.Read(new byte[15], 0, 15));
+                Assert.Equal(15, await stream.ReadAsync(new byte[15], 0, 15));
                 upgraded = true;
                 waitHandle.Set();
             }))
@@ -131,7 +131,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
                 using (Stream stream = await SendOpaqueRequestAsync("GET", address))
                 {
                     stream.Write(new byte[15], 0, 15);
-                    Assert.True(waitHandle.WaitOne(TimeSpan.FromSeconds(1)), "Timed out");
+                    Assert.True(waitHandle.WaitOne(TimeSpan.FromSeconds(10)), "Timed out");
                     Assert.True(upgraded.HasValue, "Upgraded not set");
                     Assert.True(upgraded.Value, "Upgrade failed");
                 }

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/RequestBodyLimitTests.cs

@@ -21,6 +21,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, options => options.MaxRequestBodySize = 11, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 var feature = httpContext.Features.Get<IHttpMaxRequestBodySizeFeature>();
                 Assert.NotNull(feature);
                 Assert.False(feature.IsReadOnly);
@@ -86,6 +87,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, options => options.MaxRequestBodySize = 11, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 var feature = httpContext.Features.Get<IHttpMaxRequestBodySizeFeature>();
                 Assert.NotNull(feature);
                 Assert.False(feature.IsReadOnly);
@@ -151,6 +153,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, options => options.MaxRequestBodySize = 10, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 var feature = httpContext.Features.Get<IHttpMaxRequestBodySizeFeature>();
                 Assert.NotNull(feature);
                 Assert.False(feature.IsReadOnly);
@@ -220,6 +223,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, options => options.MaxRequestBodySize = 10, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 var feature = httpContext.Features.Get<IHttpMaxRequestBodySizeFeature>();
                 Assert.NotNull(feature);
                 Assert.False(feature.IsReadOnly);
@@ -290,6 +294,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, options => options.MaxRequestBodySize = 10, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 var feature = httpContext.Features.Get<IHttpMaxRequestBodySizeFeature>();
                 Assert.NotNull(feature);
                 Assert.False(feature.IsReadOnly);

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/RequestBodyTests.cs

@@ -9,6 +9,7 @@ using System.Net.Sockets;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Testing.xunit;
 using Xunit;
 
@@ -23,6 +24,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             using (Utilities.CreateHttpServer(out address, httpContext =>
             {
                 byte[] input = new byte[100];
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 int read = httpContext.Request.Body.Read(input, 0, input.Length);
                 httpContext.Response.ContentLength = read;
                 httpContext.Response.Body.Write(input, 0, read);
@@ -75,6 +77,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 byte[] input = new byte[100];
                 Assert.Throws<ArgumentNullException>("buffer", () => httpContext.Request.Body.Read(null, 0, 1));
                 Assert.Throws<ArgumentOutOfRangeException>("offset", () => httpContext.Request.Body.Read(input, -1, 1));
@@ -99,6 +102,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             using (Utilities.CreateHttpServer(out address, httpContext =>
             {
                 byte[] input = new byte[10];
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 int read = httpContext.Request.Body.Read(input, 0, input.Length);
                 Assert.Equal(5, read);
                 content.Block.Release();

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/ResponseBodyTests.cs

@@ -9,6 +9,7 @@ using System.Net.Http;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Testing.xunit;
 using Xunit;
 
@@ -22,6 +23,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 httpContext.Response.Body.Write(new byte[10], 0, 10);
                 return httpContext.Response.Body.WriteAsync(new byte[10], 0, 10);
             }))
@@ -42,6 +44,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, async httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 httpContext.Response.Body.Write(new byte[10], 0, 10);
                 await httpContext.Response.Body.WriteAsync(new byte[10], 0, 10);
                 await httpContext.Response.Body.FlushAsync();
@@ -85,6 +88,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, async httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 httpContext.Response.Headers["Content-lenGth"] = " 30 ";
                 Stream stream = httpContext.Response.Body;
                 stream.EndWrite(stream.BeginWrite(new byte[10], 0, 10, null, null));
@@ -124,8 +128,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             using (Utilities.CreateHttpServer(out address, httpContext =>
             {
                 httpContext.Response.Headers["Content-lenGth"] = " 20 ";
-                httpContext.Response.Body.Write(new byte[5], 0, 5);
+                return httpContext.Response.Body.WriteAsync(new byte[5], 0, 5);
-                return Task.FromResult(0);
             }))
             {
                 Assert.Throws<AggregateException>(() => SendRequestAsync(address).Result);
@@ -137,13 +140,13 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         {
             var completed = false;
             string address;
-            using (Utilities.CreateHttpServer(out address, httpContext =>
+            using (Utilities.CreateHttpServer(out address, async httpContext =>
             {
                 httpContext.Response.Headers["Content-lenGth"] = " 10 ";
-                httpContext.Response.Body.Write(new byte[5], 0, 5);
+                await httpContext.Response.Body.WriteAsync(new byte[5], 0, 5);
-                Assert.Throws<InvalidOperationException>(() => httpContext.Response.Body.Write(new byte[6], 0, 6));
+                await Assert.ThrowsAsync<InvalidOperationException>(() =>
+                    httpContext.Response.Body.WriteAsync(new byte[6], 0, 6));
                 completed = true;
-                return Task.FromResult(0);
             }))
             {
                 await Assert.ThrowsAsync<HttpRequestException>(() => SendRequestAsync(address));
@@ -161,6 +164,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             {
                 try
                 {
+                    httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                     httpContext.Response.Headers["Content-lenGth"] = " 10 ";
                     httpContext.Response.Body.Write(new byte[10], 0, 10);
                     httpContext.Response.Body.Write(new byte[9], 0, 9);
@@ -197,6 +201,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, httpContext =>
             {
+                httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                 httpContext.Response.OnStarting(state =>
                 {
                     onStartingCalled = true;

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/ResponseHeaderTests.cs

@@ -130,8 +130,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
                 var responseInfo = httpContext.Features.Get<IHttpResponseFeature>();
                 var responseHeaders = responseInfo.Headers;
                 responseHeaders["Connection"] = new string[] { "Close" };
-                httpContext.Response.Body.Flush(); // Http.Sys adds the Content-Length: header for us if we don't flush
+                return httpContext.Response.Body.FlushAsync(); // Http.Sys adds the Content-Length: header for us if we don't flush
-                return Task.FromResult(0);
             }))
             {
                 HttpResponseMessage response = await SendRequestAsync(address);
@@ -204,6 +203,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             string address;
             using (Utilities.CreateHttpServer(out address, httpContext =>
                 {
+                    httpContext.Features.Get<IHttpBodyControlFeature>().AllowSynchronousIO = true;
                     var responseInfo = httpContext.Features.Get<IHttpResponseFeature>();
                     var responseHeaders = responseInfo.Headers;
                     responseHeaders.Add("Custom1", new string[] { "value1a", "value1b" });

test/Microsoft.AspNetCore.Server.HttpSys.FunctionalTests/ServerTests.cs

@@ -53,12 +53,12 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         public async Task Server_EchoHelloWorld_Success()
         {
             string address;
-            using (Utilities.CreateHttpServer(out address, httpContext =>
+            using (Utilities.CreateHttpServer(out address, async httpContext =>
                 {
-                    string input = new StreamReader(httpContext.Request.Body).ReadToEnd();
+                    var input = await new StreamReader(httpContext.Request.Body).ReadToEndAsync();
                     Assert.Equal("Hello World", input);
                     httpContext.Response.ContentLength = 11;
-                    return httpContext.Response.WriteAsync("Hello World");
+                    await httpContext.Response.WriteAsync("Hello World");
                 }))
             {
                 string response = await SendRequestAsync(address, "Hello World");