Merge pull request #11484 from yogpan01/mbed-coap-v5.1.1

Delaying message id random initialization to later stage.

Author: 0xc0170

features/frameworks/mbed-coap/CHANGELOG.md

@@ -1,5 +1,13 @@
 # Change Log
 
+## [v5.1.1](https://github.com/ARMmbed/mbed-coap/releases/tag/v5.1.1)
+
+- Delay the random initialization of message id to a later phase and not during init() so there is enough time
+  for system to complete the rest of the initialization.
+
+-[Full Changelog](https://github.com/ARMmbed/mbed-coap/compare/v5.1.0...v5.1.1)
+
+
 ## [v5.1.0](https://github.com/ARMmbed/mbed-coap/releases/tag/v5.1.0)
 
 - Introduce SN_COAP_REDUCE_BLOCKWISE_HEAP_FOOTPRINT configuration flag. 

features/frameworks/mbed-coap/source/sn_coap_protocol.c

@@ -179,13 +179,7 @@ struct coap_s *sn_coap_protocol_init(void *(*used_malloc_func_ptr)(uint16_t), vo
 
 #endif /* ENABLE_RESENDINGS */
 
-    /* Randomize global message ID */
-    randLIB_seed_random();
-    message_id = randLIB_get_16bit();
-    if (message_id == 0) {
-        message_id = 1;
-    }
-
+    message_id = 0;
     return handle;
 }
 
@@ -2526,6 +2520,11 @@ static bool compare_address_and_port(const sn_nsdl_addr_s* left, const sn_nsdl_a
 
 static uint16_t get_new_message_id(void)
 {
+    if (message_id == 0) {
+        /* Randomize global message ID */
+        randLIB_seed_random();
+        message_id = randLIB_get_16bit();
+    }
     message_id++;
     if (message_id == 0) {
         message_id = 1;