coverity reported error fixes. (ARMmbed#1770)

CIDs 271912, 271441, and 270647 are fixed by this pull request.

Author: deepakvenugopal

source/6LoWPAN/Thread/thread_extension_bbr.c

@@ -1078,7 +1078,16 @@ static int thread_extension_bbr_pbbr_start(thread_pbbr_t *this)
     this->pbbr_multicast_address[1] = 0x32; //Thread specification says p and t bits are 1
     this->pbbr_multicast_address[2] = 0x00; //Reserved
     this->pbbr_multicast_address[3] = 0x40; //Prefix length 64 bits
-    thread_extension_network_prefix_get(cur->id, NULL, &this->pbbr_multicast_address[4], NULL);
+    if (!thread_extension_network_prefix_get(cur->id, NULL, &this->pbbr_multicast_address[4], NULL)) {
+        this->pbbr_multicast_address[4] = 0xfd;
+        this->pbbr_multicast_address[5] = 0x00;
+        this->pbbr_multicast_address[6] = 0x7d;
+        this->pbbr_multicast_address[7] = 0x03;
+        this->pbbr_multicast_address[8] = 0x7d;
+        this->pbbr_multicast_address[9] = 0x03;
+        this->pbbr_multicast_address[10] = 0x7d;
+        this->pbbr_multicast_address[11] = 0x03;
+    }
     this->pbbr_multicast_address[15] = 3;
 
     tr_info("pBBR service started (Commercial network)");
@@ -1141,16 +1150,18 @@ int8_t thread_extension_bbr_init(int8_t interface_id, int8_t backbone_interface_
     this->joiner_router_rloc = 0xffff;
     this->coap_nmkp_virtual_service_id = -1;
     this->br_bb_service_id = -1;
-    // Default domain prefix for PBBR
-    this->domain_prefix[0] = 0xfd;
-    this->domain_prefix[2] = 0x7d;
-    this->domain_prefix[3] = 0x03;
-    this->domain_prefix[4] = 0x7d;
-    this->domain_prefix[5] = 0x03;
-    this->domain_prefix[6] = 0x7d;
-    this->domain_prefix[7] = 0x03;
-
-    thread_extension_network_prefix_get(interface_id, NULL, this->domain_prefix, NULL);
+    // Default domain prefix for PBBR - will be updated once domain prefix is in network data
+    if (0 != thread_extension_network_prefix_get(interface_id, NULL, this->domain_prefix, NULL)) {
+        this->domain_prefix[0] = 0xfd;
+        this->domain_prefix[1] = 0x00;
+        this->domain_prefix[2] = 0x7d;
+        this->domain_prefix[3] = 0x03;
+        this->domain_prefix[4] = 0x7d;
+        this->domain_prefix[5] = 0x03;
+        this->domain_prefix[6] = 0x7d;
+        this->domain_prefix[7] = 0x03;
+    }
+
     this->coap_service_id = coap_service_initialize(this->interface_id, THREAD_MANAGEMENT_PORT, COAP_SERVICE_OPTIONS_NONE, NULL, NULL);
     if (this->coap_service_id < 0) {
         tr_warn("Thread border router coap init failed");

source/6LoWPAN/Thread/thread_network_synch.c

@@ -238,7 +238,7 @@ void thread_dynamic_storage_build_mle_table(int8_t interface_id)
 {
     tr_debug("Dynamic storage: building MLE table.");
     protocol_interface_info_entry_t *cur = protocol_stack_interface_info_get_by_id(interface_id);
-    if (!cur && cur->mac_parameters) {
+    if (!cur || !cur->mac_parameters) {
         return;
     }