Don't crash the server if a connection filter throws synchronously.

src/Microsoft.AspNet.Server.Kestrel/Http/Connection.cs

@@ -78,6 +78,8 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
                     Address = ServerAddress
                 };
 
+                try
+                {
                     ConnectionFilter.OnConnection(_filterContext).ContinueWith((task, state) =>
                     {
                         var connection = (Connection)state;
@@ -98,6 +100,12 @@ namespace Microsoft.AspNet.Server.Kestrel.Http
                         }
                     }, this);
                 }
+                catch (Exception ex)
+                {
+                    Log.LogError("ConnectionFilter.OnConnection", ex);
+                    ConnectionControl.End(ProduceEndType.SocketDisconnect);
+                }
+            }
         }
 
         public void Abort()

test/Microsoft.AspNet.Server.KestrelTests/ConnectionFilterTests.cs

@@ -1,6 +1,7 @@
 // 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;
 using System.IO;
 using System.Threading.Tasks;
 using Microsoft.AspNet.Http;
@@ -82,6 +83,35 @@ namespace Microsoft.AspNet.Server.KestrelTests
             }
         }
 
+        [ConditionalFact]
+        [FrameworkSkipCondition(RuntimeFrameworks.Mono, SkipReason = "Test hangs after execution on Mono.")]
+        public async Task ThrowingSynchronousConnectionFilterDoesNotCrashServer()
+        {
+            var serviceContext = new TestServiceContext()
+            {
+                ConnectionFilter = new ThrowingConnectionFilter()
+            };
+
+            using (var server = new TestServer(App, serviceContext))
+            {
+                using (var connection = new TestConnection())
+                {
+                    try
+                    {
+                        await connection.SendEnd(
+                            "POST / HTTP/1.0",
+                            "",
+                            "Hello World?");
+                    }
+                    catch (IOException)
+                    {
+                        // Will throw because the exception in the connection filter will close the connection.
+                        Assert.True(true);
+                    }
+                }
+            }
+        }
+
         private class RewritingConnectionFilter : IConnectionFilter
         {
             private static Task _empty = Task.FromResult<object>(null);
@@ -112,6 +142,14 @@ namespace Microsoft.AspNet.Server.KestrelTests
             }
         }
 
+        private class ThrowingConnectionFilter : IConnectionFilter
+        {
+            public Task OnConnection(ConnectionFilterContext context)
+            {
+                throw new Exception();
+            }
+        }
+
         private class RewritingStream : Stream
         {
             private readonly Stream _innerStream;