From f4730e78f85f6f6b326e702d0db0fea4914e5632 Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon@gmx.de>
Date: Fri, 21 Apr 2017 09:43:44 +0200
Subject: [PATCH] sntp: use randomized startup delay ([0..5] seconds) by
 default (if LWIP_RAND is available)

---
 src/include/lwip/apps/sntp_opts.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/include/lwip/apps/sntp_opts.h b/src/include/lwip/apps/sntp_opts.h
index 16585a5a..499dd9e4 100644
--- a/src/include/lwip/apps/sntp_opts.h
+++ b/src/include/lwip/apps/sntp_opts.h
@@ -140,14 +140,18 @@
  * Turned off by default.
  */
 #if !defined SNTP_STARTUP_DELAY || defined __DOXYGEN__
+#ifdef LWIP_RAND
+#define SNTP_STARTUP_DELAY          1
+#else
 #define SNTP_STARTUP_DELAY          0
 #endif
+#endif
 
 /** If you want the startup delay to be a function, define this
  * to a function (including the brackets) and define SNTP_STARTUP_DELAY to 1.
  */
 #if !defined SNTP_STARTUP_DELAY_FUNC || defined __DOXYGEN__
-#define SNTP_STARTUP_DELAY_FUNC     SNTP_STARTUP_DELAY
+#define SNTP_STARTUP_DELAY_FUNC     (LWIP_RAND() % 5000)
 #endif
 
 /** SNTP receive timeout - in milliseconds