From 62f14054ebe3f2dd2b7e7faedcd898322efdbe19 Mon Sep 17 00:00:00 2001
From: James Newton-King <james@newtonking.com>
Date: Mon, 16 Apr 2018 10:41:35 +1200
Subject: [PATCH] Capture and log prematurely closed connections

---
 .../Internal/Transports/WebSocketsTransport.Log.cs       | 7 +++++++
 .../Internal/Transports/WebSocketsTransport.cs           | 9 +++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.Log.cs b/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.Log.cs
index 13df2672c6..29067a65b5 100644
--- a/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.Log.cs
+++ b/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.Log.cs
@@ -50,6 +50,9 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal.Transports
             private static readonly Action<ILogger, Exception> _sendFailed =
                 LoggerMessage.Define(LogLevel.Error, new EventId(13, "SendFailed"), "Socket failed to send.");
 
+            private static readonly Action<ILogger, Exception> _closedPrematurely =
+                LoggerMessage.Define(LogLevel.Debug, new EventId(14, "ClosedPrematurely"), "Socket connection closed prematurely.");
+
             public static void SocketOpened(ILogger logger, string subProtocol)
             {
                 _socketOpened(logger, subProtocol, null);
@@ -115,6 +118,10 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal.Transports
                 _sendFailed(logger, ex);
             }
 
+            public static void ClosedPrematurely(ILogger logger, Exception ex)
+            {
+                _closedPrematurely(logger, ex);
+            }
         }
     }
 }
diff --git a/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.cs b/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.cs
index 3632e29c52..0442ae6a5f 100644
--- a/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.cs
+++ b/src/Microsoft.AspNetCore.Http.Connections/Internal/Transports/WebSocketsTransport.cs
@@ -182,13 +182,10 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal.Transports
                     }
                 }
             }
-            catch (WebSocketException ex) when (
-                ex.ErrorCode == 997 ||
-                // Sometimes this error is raised without the ErrorCode
-                ex.Message == "The remote party closed the WebSocket connection without completing the close handshake.")
+            catch (WebSocketException ex) when (ex.WebSocketErrorCode == WebSocketError.ConnectionClosedPrematurely)
             {
-                // The remote party closed the WebSocket connection without completing the close handshake
-                // Don't long an error for this exception
+                // Client has closed the WebSocket connection without completing the close handshake
+                Log.ClosedPrematurely(_logger, ex);
             }
             catch (OperationCanceledException)
             {