add_timeout
add_timeout(cur_time + ip->client->interval, send_discover, ip);
add_timeout(
add_timeout(cur_time + ip->client->config->retry_interval, state_init,
add_timeout(cur_time + ip->client->interval, send_request, ip);
add_timeout(ip->client->active->renewal, state_bound, ip);
void add_timeout(time_t, void (*)(void *), void *);