From a611e44f9a7d598bbbffe73f59e592739ddfeeaa Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Tue, 29 Nov 2016 11:28:26 +1100
Subject: [PATCH] 4519.   [port]          win32: handle ERROR_MORE_DATA. [RT
 #43534]

---
 CHANGES                | 2 ++
 lib/isc/win32/socket.c | 8 +++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/CHANGES b/CHANGES
index 0e18b48abe..dda1f6c315 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+4519.	[port]		win32: handle ERROR_MORE_DATA. [RT #43534]
+
 4518.	[func]		The "print-time" option in the logging configuration
 			can now take arguments "local", "iso8601" or
 			"iso8601-utc" to indicate the format in which the
diff --git a/lib/isc/win32/socket.c b/lib/isc/win32/socket.c
index ca032d2210..133f31a84e 100644
--- a/lib/isc/win32/socket.c
+++ b/lib/isc/win32/socket.c
@@ -2515,14 +2515,16 @@ SocketIoThread(LPVOID ThreadContext) {
 
 		request = lpo->request_type;
 
-		errstatus = 0;
-		if (!bSuccess) {
+		if (!bSuccess)
+			errstatus = GetLastError();
+		else
+			errstatus = 0;
+		if (!bSuccess && errstatus != ERROR_MORE_DATA) {
 			isc_result_t isc_result;
 
 			/*
 			 * Did the I/O operation complete?
 			 */
-			errstatus = GetLastError();
 			isc_result = isc__errno2result(errstatus);
 
 			LOCK(&sock->lock);