Handle incoming HTTP requests being canceled gracefully (#2314)

src/Microsoft.AspNetCore.Http.Connections/Internal/HttpConnectionDispatcher.Log.cs

@@ -49,6 +49,9 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal
             private static readonly Action<ILogger, string, Exception> _connectionDisposedWhileWriteInProgress =
                 LoggerMessage.Define<string>(LogLevel.Debug, new EventId(13, "ConnectionDisposedWhileWriteInProgress"), "Connection {TransportConnectionId} was disposed while a write was in progress.");
 
+            private static readonly Action<ILogger, string, Exception> _failedToReadHttpRequestBody =
+                LoggerMessage.Define<string>(LogLevel.Debug, new EventId(14, "FailedToReadHttpRequestBody"), "Connection {TransportConnectionId} failed to read the HTTP request body.");
+
             public static void ConnectionDisposed(ILogger logger, string connectionId)
             {
                 _connectionDisposed(logger, connectionId, null);
@@ -113,6 +116,11 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal
             {
                 _connectionDisposedWhileWriteInProgress(logger, connectionId, ex);
             }
+
+            public static void FailedToReadHttpRequestBody(ILogger logger, string connectionId, Exception ex)
+            {
+                _failedToReadHttpRequestBody(logger, connectionId, ex);
+            }
         }
     }
 }

src/Microsoft.AspNetCore.Http.Connections/Internal/HttpConnectionDispatcher.cs

@@ -505,6 +505,15 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal
                         context.Response.ContentType = "text/plain";
                         return;
                     }
+                    catch (IOException ex)
+                    {
+                        // Can occur when the HTTP request is canceled by the client
+                        Log.FailedToReadHttpRequestBody(_logger, connection.ConnectionId, ex);
+
+                        context.Response.StatusCode = StatusCodes.Status400BadRequest;
+                        context.Response.ContentType = "text/plain";
+                        return;
+                    }
 
                     Log.ReceivedBytes(_logger, connection.ApplicationStream.Length);
                 }

test/Microsoft.AspNetCore.Http.Connections.Tests/HttpConnectionDispatcherTests.cs

@@ -25,6 +25,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Testing;
 using Microsoft.Extensions.Primitives;
+using Moq;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using Xunit;
@@ -719,6 +720,44 @@ namespace Microsoft.AspNetCore.Http.Connections.Tests
             }
         }
 
+        [Theory]
+        [InlineData(HttpTransportType.LongPolling)]
+        [InlineData(HttpTransportType.ServerSentEvents)]
+        public async Task IOExceptionWhenReadingRequestReturns400Response(HttpTransportType transportType)
+        {
+            using (StartVerifiableLog(out var loggerFactory, LogLevel.Debug))
+            {
+                var manager = CreateConnectionManager(loggerFactory);
+                var dispatcher = new HttpConnectionDispatcher(manager, loggerFactory);
+                var connection = manager.CreateConnection();
+                connection.TransportType = transportType;
+
+                var mockStream = new Mock<Stream>();
+                mockStream.Setup(m => m.CopyToAsync(It.IsAny<Stream>(), It.IsAny<int>(), It.IsAny<CancellationToken>())).Throws(new IOException());
+
+                using (var responseBody = new MemoryStream())
+                {
+                    var context = new DefaultHttpContext();
+                    context.Request.Body = mockStream.Object;
+                    context.Response.Body = responseBody;
+
+                    var services = new ServiceCollection();
+                    services.AddSingleton<TestConnectionHandler>();
+                    services.AddOptions();
+                    context.Request.Path = "/foo";
+                    context.Request.Method = "POST";
+                    var values = new Dictionary<string, StringValues>();
+                    values["id"] = connection.ConnectionId;
+                    var qs = new QueryCollection(values);
+                    context.Request.Query = qs;
+
+                    await dispatcher.ExecuteAsync(context, new HttpConnectionDispatcherOptions(), c => Task.CompletedTask);
+
+                    Assert.Equal(StatusCodes.Status400BadRequest, context.Response.StatusCode);
+                }
+            }
+        }
+
         [Fact]
         public async Task EndpointsThatRequireConnectionId400WhenNoConnectionIdProvidedForPost()
         {