From eb0f9c9529683b217fac534f99d5b04c628016c7 Mon Sep 17 00:00:00 2001
From: Michael Adelson <mike.adelson314@gmail.com>
Date: Sat, 3 Dec 2022 10:07:14 -0500
Subject: [PATCH] attempt to fix connection loss issue

(cherry picked from commit 4f6118ee5b51385f7fedd5a2ca7f2367e8077b2d)
---
 .../src/ZooKeeperNetEx/utils/SocketContext.cs | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/csharp/src/ZooKeeperNetEx/utils/SocketContext.cs b/src/csharp/src/ZooKeeperNetEx/utils/SocketContext.cs
index 1158f946159..9085ea48218 100644
--- a/src/csharp/src/ZooKeeperNetEx/utils/SocketContext.cs
+++ b/src/csharp/src/ZooKeeperNetEx/utils/SocketContext.cs
@@ -74,7 +74,9 @@ public SocketAsyncOperation GetResult()
 
             var socketAsyncEventArgs = _socketAsyncEventArgs; 
 
-            if (socketAsyncEventArgs.LastOperation == SocketAsyncOperation.Receive && _socket.Available == 0)
+            if (socketAsyncEventArgs.LastOperation == SocketAsyncOperation.Receive 
+                && _socket.Available == 0
+                && !IsSocketConnected())
             {
                 socketAsyncEventArgs.SocketError = SocketError.ConnectionReset;
             }
@@ -85,6 +87,25 @@ public SocketAsyncOperation GetResult()
             }
             return socketAsyncEventArgs.LastOperation;
         }
+
+        private bool IsSocketConnected()
+        {
+            // based on https://learn.microsoft.com/en-us/dotnet/api/system.net.sockets.socket.connected
+
+            var originalBlockingState = _socket.Blocking;
+            try
+            {
+                _socket.Blocking = false;
+                _socket.Send(new byte[1], size: 0, SocketFlags.None);
+            }
+            catch (SocketException) { }
+            finally
+            {
+                _socket.Blocking = originalBlockingState;
+            }
+
+            return _socket.Connected;
+        }
       
         private void ThrowIfDisposed()
         {