Handle early disconnects #141

src/Microsoft.Owin.Host.HttpListener/DisconnectHandler.cs

@@ -16,6 +16,9 @@ namespace Microsoft.Owin.Host.HttpListener
 
     internal class DisconnectHandler
     {
+        // Win8 minimum
+        private static bool SkipIOCPCallbackOnSuccess = Environment.OSVersion.Version >= new Version(6, 2);
+
         private readonly ConcurrentDictionary<ulong, ConnectionCancellation> _connectionCancellationTokens;
         private readonly System.Net.HttpListener _listener;
         private readonly CriticalHandle _requestQueueHandle;
@@ -114,6 +117,15 @@ namespace Microsoft.Owin.Host.HttpListener
                 cts.Cancel();
             }
 
+            if (hr == NativeMethods.HttpErrors.NO_ERROR && SkipIOCPCallbackOnSuccess)
+            {
+                // IO operation completed synchronously - callback won't be called to signal completion
+                Overlapped.Free(nativeOverlapped);
+                ConnectionCancellation cancellation;
+                _connectionCancellationTokens.TryRemove(connectionId, out cancellation);
+                cts.Cancel();
+            }
+
             return returnToken;
         }
 

tests/Microsoft.Owin.Host.HttpListener.Tests/OwinHttpListenerTests.cs

@@ -342,6 +342,46 @@ namespace Microsoft.Owin.Host.HttpListener.Tests
             }
         }
 
+        [Fact]
+        public void Disconnect_ClientDisconnects_Before_CancellationToken_Created()
+        {
+            var requestReceived = new ManualResetEvent(false);
+            var requestCanceled = new ManualResetEvent(false);
+
+            var clientDisposed = new ManualResetEvent(false);
+
+            OwinHttpListener listener = CreateServer(
+                env =>
+                {
+                    requestReceived.Set();
+
+                    // lets wait for client to be gone
+                    Assert.True(clientDisposed.WaitOne(1000));
+
+                    // the most important part is not to observe CancellationToken before client disconnects
+
+                    GetCallCancelled(env).Register(() => requestCanceled.Set());
+                    return Task.FromResult(0);
+                },
+                HttpServerAddress);
+
+            using (listener)
+            {
+                using (var client = new HttpClient())
+                {
+                    var requestTask = client.GetAsync(HttpClientAddress);
+                    Assert.True(requestReceived.WaitOne(1000));
+                    client.CancelPendingRequests();
+
+                    Assert.Throws<AggregateException>(() => requestTask.Result);
+                }
+
+                clientDisposed.Set();
+
+                Assert.True(requestCanceled.WaitOne(1000));
+            }
+        }
+
         private static CancellationToken GetCallCancelled(IDictionary<string, object> env)
         {
             return env.Get<CancellationToken>("owin.CallCancelled");