in6p_ip6_nxt
if (in6p->in6p_ip6_nxt != IPPROTO_ICMPV6)
if (in6p->in6p_ip6_nxt &&
in6p->in6p_ip6_nxt != proto)
ip6->ip6_nxt = in6p->in6p_ip6_nxt;
inp->in6p_ip6_nxt = (long)proto;