int
rpl_process_parent_event(rpl_dag_t *dag, rpl_parent_t *p)
{
rpl_rank_t parent_rank;
rpl_rank_t old_rank;
/* Update the parent rank. */
parent_rank = p->rank;
old_rank = dag->rank;
if(rpl_select_parent(dag) == NULL) {
/* No suitable parent; trigger a local repair. */
PRINTF("RPL: No parents found in a DAG\n");
rpl_local_repair(dag);
return 1;
}
if(DAG_RANK(old_rank, dag) != DAG_RANK(dag->rank, dag)) {
if(dag->rank < dag->min_rank) {
dag->min_rank = dag->rank;
}
PRINTF("RPL: Moving in the DAG from rank %hu to %hu\n",
DAG_RANK(old_rank, dag), DAG_RANK(dag->rank, dag));
PRINTF("RPL: The preferred parent is ");
PRINT6ADDR(&dag->preferred_parent->addr);
PRINTF(" (rank %u)\n",
(unsigned)DAG_RANK(dag->preferred_parent->rank, dag));
rpl_reset_dio_timer(dag, 1);
}
if(parent_rank == INFINITE_RANK ||
!acceptable_rank(dag, dag->of->calculate_rank(NULL, parent_rank))) {
/* The candidate parent is no longer valid: the rank increase resulting
from the choice of it as a parent would be too high. */
return 0;
}
return 1;
}
/*---------------------------------------------------------------------------*/
rpl_dag_t *
rpl_select_dag(rpl_instance_t *instance, rpl_parent_t *p)
{
rpl_parent_t *last_parent;
rpl_dag_t *dag, *end, *best_dag;
rpl_rank_t old_rank;
old_rank = instance->current_dag->rank;
last_parent = instance->current_dag->preferred_parent;
if(instance->current_dag->rank != ROOT_RANK(instance)) {
rpl_select_parent(p->dag);
}
best_dag = NULL;
for(dag = &instance->dag_table[0], end = dag + RPL_MAX_DAG_PER_INSTANCE; dag < end; ++dag) {
if(dag->used && dag->preferred_parent != NULL && dag->preferred_parent->rank != INFINITE_RANK) {
if(best_dag == NULL) {
best_dag = dag;
} else {
best_dag = instance->of->best_dag(best_dag, dag);
}
}
}
if(best_dag == NULL) {
/* No parent found: the calling function handle this problem. */
return NULL;
}
if(instance->current_dag != best_dag) {
/* Remove routes installed by DAOs. */
rpl_remove_routes(instance->current_dag);
PRINTF("RPL: New preferred DAG: ");
PRINT6ADDR(&best_dag->dag_id);
PRINTF("\n");
if(best_dag->prefix_info.flags & UIP_ND6_RA_FLAG_AUTONOMOUS) {
check_prefix(&instance->current_dag->prefix_info, &best_dag->prefix_info);
} else if(instance->current_dag->prefix_info.flags & UIP_ND6_RA_FLAG_AUTONOMOUS) {
check_prefix(&instance->current_dag->prefix_info, NULL);
}
best_dag->joined = 1;
instance->current_dag->joined = 0;
instance->current_dag = best_dag;
}
instance->of->update_metric_container(instance);
/* Update the DAG rank. */
best_dag->rank = instance->of->calculate_rank(best_dag->preferred_parent, 0);
if(last_parent == NULL || best_dag->rank < best_dag->min_rank) {
best_dag->min_rank = best_dag->rank;
} else if(!acceptable_rank(best_dag, best_dag->rank)) {
PRINTF("RPL: New rank unacceptable!\n");
rpl_set_preferred_parent(instance->current_dag, NULL);
if(instance->mop != RPL_MOP_NO_DOWNWARD_ROUTES && last_parent != NULL) {
/* Send a No-Path DAO to the removed preferred parent. */
dao_output(last_parent, RPL_ZERO_LIFETIME);
}
return NULL;
}
if(best_dag->preferred_parent != last_parent) {
rpl_set_default_route(instance, rpl_get_parent_ipaddr(best_dag->preferred_parent));
PRINTF("RPL: Changed preferred parent, rank changed from %u to %u\n",
(unsigned)old_rank, best_dag->rank);
RPL_STAT(rpl_stats.parent_switch++);
if(instance->mop != RPL_MOP_NO_DOWNWARD_ROUTES) {
if(last_parent != NULL) {
/* Send a No-Path DAO to the removed preferred parent. */
dao_output(last_parent, RPL_ZERO_LIFETIME);
}
/* The DAO parent set changed - schedule a DAO transmission. */
RPL_LOLLIPOP_INCREMENT(instance->dtsn_out);
rpl_schedule_dao(instance);
}
rpl_reset_dio_timer(instance);
#if DEBUG
rpl_print_neighbor_list();
#endif
} else if(best_dag->rank != old_rank) {
PRINTF("RPL: Preferred parent update, rank changed from %u to %u\n",
(unsigned)old_rank, best_dag->rank);
}
return best_dag;
}