MAKE_EXTHDR
MAKE_EXTHDR(opt->ip6po_hbh, &exthdrs.ip6e_hbh);
MAKE_EXTHDR(opt->ip6po_dest1, &exthdrs.ip6e_dest1);
MAKE_EXTHDR(opt->ip6po_rthdr, &exthdrs.ip6e_rthdr);
MAKE_EXTHDR(opt->ip6po_dest2, &exthdrs.ip6e_dest2);