mesh: simplify network key index management

src/mesh/mesh_configuration_server.c

@@ -623,7 +623,7 @@ static void config_netkey_add_handler(mesh_model_t * mesh_model, mesh_pdu_t * pd
 
         // check limit for pts
         uint16_t internal_index = mesh_network_key_get_free_index();
-        if (internal_index == 0 || (config_netkey_list_max && mesh_network_key_list_count() >= config_netkey_list_max)){
+        if (internal_index == MESH_KEYS_INVALID_INDEX || (config_netkey_list_max && mesh_network_key_list_count() >= config_netkey_list_max)){
             status = MESH_FOUNDATION_STATUS_INSUFFICIENT_RESOURCES;
         } else {
 
@@ -709,10 +709,17 @@ static void config_netkey_update_handler(mesh_model_t * mesh_model, mesh_pdu_t *
         return;
     }
 
-    // setup new key
+    // get index for new key
     uint16_t internal_index = mesh_network_key_get_free_index();
+    if (internal_index == MESH_KEYS_INVALID_INDEX){
+        config_netkey_status(mesh_model, mesh_pdu_netkey_index(pdu), mesh_pdu_src(pdu), MESH_FOUNDATION_STATUS_INSUFFICIENT_RESOURCES, netkey_index);
+        mesh_access_message_processed(access_pdu_in_process);
+        return;
+    }
+
+    // get new key
     mesh_network_key_t * new_network_key = btstack_memory_mesh_network_key_get();
-    if (internal_index == 0 || new_network_key == NULL){
+    if (new_network_key == NULL){
         config_netkey_status(mesh_model, mesh_pdu_netkey_index(pdu), mesh_pdu_src(pdu), MESH_FOUNDATION_STATUS_INSUFFICIENT_RESOURCES, netkey_index);
         mesh_access_message_processed(access_pdu_in_process);
         return;

src/mesh/mesh_keys.c

@@ -55,14 +55,13 @@ void mesh_network_key_init(void){
 }
 
 uint16_t mesh_network_key_get_free_index(void){
-    // find empty slot, skip slot #0 reserved for primary network key
     uint16_t i;
-    for (i=1;i < MAX_NR_MESH_NETWORK_KEYS ; i++){
+    for (i=0;i < MAX_NR_MESH_NETWORK_KEYS ; i++){
         if (mesh_network_key_used[i] == 0){
             return i;
         }
     }
-    return 0;
+    return MESH_KEYS_INVALID_INDEX;
 }
 
 void mesh_network_key_add(mesh_network_key_t * network_key){

src/mesh/mesh_keys.h

@@ -49,6 +49,8 @@ extern "C"
 {
 #endif
 
+#define MESH_KEYS_INVALID_INDEX 0xffff
+
 typedef struct {
     btstack_linked_item_t item;
 
@@ -134,7 +136,7 @@ void mesh_network_key_init(void);
 /**
  * @brief Get internal index of free network key storage entry
  * @note index 0 is reserved for primary network key
- * @returns index or 0u if none found
+ * @returns index or MESH_KEYS_INVALID_INDEX if none found
  */
 uint16_t mesh_network_key_get_free_index(void);
 

src/mesh/provisioning_device.c

@@ -704,7 +704,8 @@ static void provisioning_handle_data_ccm(void * arg){
     // sort provisoning data
     memcpy(network_key->net_key, provisioning_data, 16);
     network_key->netkey_index = big_endian_read_16(provisioning_data, 16);
-    network_key->internal_index = 0;
+    // assume free index available for very first network key
+    network_key->internal_index = mesh_network_key_get_free_index();
     flags = provisioning_data[18];
     iv_index = big_endian_read_32(provisioning_data, 19);
     unicast_address = big_endian_read_16(provisioning_data, 23);

test/mesh/provisioning_device_test.cpp

@@ -140,6 +140,9 @@ void pb_adv_send_pdu(uint16_t pb_transport_cid, const uint8_t * pdu, uint16_t si
 }
 void pb_gatt_send_pdu(uint16_t con_handle, const uint8_t * pdu, uint16_t pdu_size){}
  
+uint16_t mesh_network_key_get_free_index(void){
+    return 0;
+}
 
 static mesh_network_key_t network_key; 
 extern "C" mesh_network_key_t * btstack_memory_mesh_network_key_get(void){