From 079cdafe0f55898de6490349fbf8fd2b6cb4a7b5 Mon Sep 17 00:00:00 2001
From: kzhioki <kzhioki@gmail.com>
Date: Thu, 12 Dec 2019 09:50:33 +0900
Subject: [PATCH] Add error recovery when UDP transfer fails

This commit does not affect normal case. Even if UDP transfer fails for
any reasons in sendNTPPacket, it can be recovered by re-initialization.
---
 NTPClient.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/NTPClient.cpp b/NTPClient.cpp
index 760e142..5ed96e1 100755
--- a/NTPClient.cpp
+++ b/NTPClient.cpp
@@ -201,7 +201,11 @@ void NTPClient::sendNTPPacket() {
     this->_udp->beginPacket(this->_poolServerIP, 123);
   }
   this->_udp->write(this->_packetBuffer, NTP_PACKET_SIZE);
-  this->_udp->endPacket();
+  if (this->_udp->endPacket() == 0) {
+    // recovery if UDP client encounters any errors
+    this->end();
+    this->begin(this->_port);
+  }
 }
 
 void NTPClient::setRandomPort(unsigned int minValue, unsigned int maxValue) {