Throw error on unexpected close (#2205)

src/Microsoft.AspNetCore.SignalR.Client.Core/HubConnection.cs

@@ -6,6 +6,7 @@ using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
+using System.IO;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Channels;
@@ -640,7 +641,8 @@ namespace Microsoft.AspNetCore.SignalR.Client
                                     break;
                                 }
                             }
-                            else if (result.IsCompleted)
+
+                            if (result.IsCompleted)
                             {
                                 // Not enough data, and we won't be getting any more data.
                                 throw new InvalidOperationException(
@@ -717,8 +719,13 @@ namespace Microsoft.AspNetCore.SignalR.Client
                                 break;
                             }
                         }
-                        else if (result.IsCompleted)
+
+                        if (result.IsCompleted)
                         {
+                            if (!buffer.IsEmpty)
+                            {
+                                throw new InvalidDataException("Connection terminated while reading a message.");
+                            }
                             break;
                         }
                     }

src/Microsoft.AspNetCore.SignalR.Core/HubConnectionContext.cs

@@ -381,12 +381,9 @@ namespace Microsoft.AspNetCore.SignalR
                                     await WriteHandshakeResponseAsync(HandshakeResponseMessage.Empty);
                                     return true;
                                 }
-                                else
-                                {
-                                    _logger.LogInformation("Didn't parse the handshake");
-                                }
                             }
-                            else if (result.IsCompleted)
+
+                            if (result.IsCompleted)
                             {
                                 // connection was closed before we ever received a response
                                 // can't send a handshake response because there is no longer a connection

src/Microsoft.AspNetCore.SignalR.Core/HubConnectionHandler.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
@@ -199,8 +200,13 @@ namespace Microsoft.AspNetCore.SignalR
                                 await _dispatcher.DispatchMessageAsync(connection, message);
                             }
                         }
-                        else if (result.IsCompleted)
+
+                        if (result.IsCompleted)
                         {
+                            if (!buffer.IsEmpty)
+                            {
+                                throw new InvalidDataException("Connection terminated while reading a message.");
+                            }
                             break;
                         }
                     }

test/Microsoft.AspNetCore.SignalR.Client.Tests/HubConnectionTests.ConnectionLifecycle.cs

 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
@@ -34,7 +35,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                     testConnection.StartAsync,
                     connection => ((TestConnection)connection).DisposeAsync());
                 builder.Services.AddSingleton<IConnectionFactory>(delegateConnectionFactory);
-				
+
                 return builder.Build();
             }
 
@@ -450,6 +451,34 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 }
             }
 
+            [Fact]
+            public async Task HubConnectionClosesWithErrorIfTerminatedWithPartialMessage()
+            {
+                var builder = new HubConnectionBuilder();
+                var innerConnection = new TestConnection();
+
+                var delegateConnectionFactory = new DelegateConnectionFactory(
+                    format => innerConnection.StartAsync(format),
+                    connection => ((TestConnection)connection).DisposeAsync());
+                builder.Services.AddSingleton<IConnectionFactory>(delegateConnectionFactory);
+
+                var hubConnection = builder.Build();
+                var closedEventTcs = new TaskCompletionSource<Exception>();
+                hubConnection.Closed += e =>
+                {
+                    closedEventTcs.SetResult(e);
+                    return Task.CompletedTask;
+                };
+
+                await hubConnection.StartAsync().OrTimeout();
+
+                await innerConnection.Application.Output.WriteAsync(Encoding.UTF8.GetBytes(new[] { '{' })).OrTimeout();
+                innerConnection.Application.Output.Complete();
+
+                var exception = await closedEventTcs.Task.OrTimeout();
+                Assert.Equal("Connection terminated while reading a message.", exception.Message);
+            }
+
             private static async Task ForceLastInvocationToComplete(TestConnection testConnection)
             {
                 // We need to "complete" the invocation

test/Microsoft.AspNetCore.SignalR.Tests/HubConnectionHandlerTests.cs

@@ -2184,6 +2184,38 @@ namespace Microsoft.AspNetCore.SignalR.Tests
             }
         }
 
+        [Fact]
+        public async Task ServerSendsCloseWithErrorWhenConnectionClosedWithPartialMessage()
+        {
+            var serviceProvider = HubConnectionHandlerTestUtils.CreateServiceProvider(services =>
+            {
+                services.AddSignalR(options => options.EnableDetailedErrors = true);
+            });
+            var connectionHandler = serviceProvider.GetService<HubConnectionHandler<SimpleHub>>();
+
+            using (var client = new TestClient())
+            {
+                var connectionHandlerTask = await client.ConnectAsync(connectionHandler).OrTimeout();
+
+                await client.Connection.Application.Output.WriteAsync(Encoding.UTF8.GetBytes(new[] { '{' })).OrTimeout();
+
+                // Close connection
+                client.Connection.Application.Output.Complete();
+
+                // Ignore message from OnConnectedAsync
+                await client.ReadAsync().OrTimeout();
+
+                var closeMessage = Assert.IsType<CloseMessage>(await client.ReadAsync().OrTimeout());
+
+                Assert.Equal("Connection closed with an error. InvalidDataException: Connection terminated while reading a message.", closeMessage.Error);
+
+                // Shut down
+                client.Dispose();
+
+                await connectionHandlerTask.OrTimeout();
+            }
+        }
+
         private class CustomHubActivator<THub> : IHubActivator<THub> where THub : Hub
         {
             public int ReleaseCount;