From 187660858fcfda1955fe2c8dbc71e1ba6378b077 Mon Sep 17 00:00:00 2001
From: Parminder Singh <61920513+parmi93@users.noreply.github.com>
Date: Thu, 20 Jul 2023 17:36:01 +0000
Subject: [PATCH] lwm2m_seed() is used to get seed

The lwm2m_seed() function is used to obtain a seed for random number
generation.
The implementation of the lwm2m_seed() function is up to the user.
---
 core/liblwm2m.c            |  4 ++--
 examples/shared/platform.c | 15 ++++++++-------
 include/liblwm2m.h         |  6 ++----
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/core/liblwm2m.c b/core/liblwm2m.c
index 4e705be97..dc924bd8a 100644
--- a/core/liblwm2m.c
+++ b/core/liblwm2m.c
@@ -68,8 +68,8 @@ lwm2m_context_t * lwm2m_init(void * userData)
     {
         memset(contextP, 0, sizeof(lwm2m_context_t));
         contextP->userData = userData;
-        lwm2m_srand((int)lwm2m_gettime());
-        contextP->nextMID = lwm2m_rand();
+        srand((int)lwm2m_seed());
+        contextP->nextMID = rand();
     }
 
     return contextP;
diff --git a/examples/shared/platform.c b/examples/shared/platform.c
index eb5a7bdaf..b194499b3 100644
--- a/examples/shared/platform.c
+++ b/examples/shared/platform.c
@@ -67,14 +67,15 @@ time_t lwm2m_gettime(void)
     return time(NULL);
 }
 
-void lwm2m_srand(unsigned int seed)
+int lwm2m_seed(void)
 {
-    srand(seed);
-}
-
-int lwm2m_rand()
-{
-    return rand();
+    /* 
+     * Return a seed for random number generation, the seed must be a 
+     * different number at every boot and unpredictable, time(NULL) may not be 
+     * a reliable source as a seed.
+     * See: https://github.com/eclipse/wakaama/pull/711
+     */
+    return time(NULL);
 }
 
 void lwm2m_printf(const char * format, ...)
diff --git a/include/liblwm2m.h b/include/liblwm2m.h
index 48c48cf45..72ad3234a 100644
--- a/include/liblwm2m.h
+++ b/include/liblwm2m.h
@@ -118,10 +118,8 @@ int lwm2m_strcasecmp(const char * str1, const char * str2);
 // In case of error, this must return a negative value.
 // Per POSIX specifications, time_t is a signed integer.
 time_t lwm2m_gettime(void);
-// Initialize random number generator
-void lwm2m_srand(unsigned int seed);
-// Get a random number
-int lwm2m_rand(void);
+// Get a seed (which must not repeat when the device reboots) for generating a random number
+int lwm2m_seed(void);
 
 #ifdef LWM2M_WITH_LOGS
 // Same usage as C89 printf()