add_pkt_subopt
if (add_pkt_subopt(dpkt, popt, DHCPV6_OPT_IAADDR,
d6so = add_pkt_subopt(dpkt, d6o, DHCPV6_OPT_IAADDR,
d6so = add_pkt_subopt(dpkt, d6so,
void *add_pkt_subopt(dhcp_pkt_t *, dhcpv6_option_t *, uint_t,