nf_reject_ip6_tcphdr_get
nf_reject_ip6_tcphdr_get(struct sk_buff *oldskb,
otcph = nf_reject_ip6_tcphdr_get(oldskb, &_otcph, &otcplen, hook);
oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook);