nd6_options
if (nd6_options(nd_rd + 1, icmp6len, &ndopts) < 0)
int nd6_options(void *, int, struct nd_opts *);
if (nd6_options(nd_ns + 1, icmp6len, &ndopts) < 0) {
if (nd6_options(nd_na + 1, icmp6len, &ndopts) < 0) {
if (nd6_options(nd_ra + 1, icmp6len, &ndopts) < 0) {
if (nd6_options(nd_rs + 1, icmp6len, &ndopts) < 0) {