npf_fetch_tcpopts
if (!npf_fetch_tcpopts(npc, &mss, &wscale)) {
bool npf_fetch_tcpopts(npf_cache_t *, uint16_t *, int *);
(void)npf_fetch_tcpopts(npc, NULL, &fstate->nst_wscale);
(void)npf_fetch_tcpopts(npc, NULL, &fstate->nst_wscale);