p->nd_opt_pi_valid_time = htonl(TIME_LEFT(addr->valid, now));
if (addr->preferred > (uint32_t)now)
p->nd_opt_pi_preferred_time = htonl(TIME_LEFT(addr->preferred, now));
p->nd_opt_pi_valid_time = htonl(TIME_LEFT(addr->valid, now));
if (addr->preferred > (uint32_t)now)
p->nd_opt_pi_preferred_time = htonl(TIME_LEFT(addr->preferred, now));