get_cached_pkt
npc = get_cached_pkt(m, NULL, NPF_RULE_LAYER_3);
npf_cache_t *npc = get_cached_pkt(m, NULL, NPF_RULE_LAYER_3);
npc = get_cached_pkt(m, t->ifname, NPF_RULE_LAYER_2);
npc = get_cached_pkt(m, t->ifname, NPF_RULE_LAYER_3);
npc = get_cached_pkt(m, t->ifname, NPF_RULE_LAYER_3);
npc = get_cached_pkt(construct_packet(p), NULL, NPF_RULE_LAYER_3);
npf_cache_t * get_cached_pkt(struct mbuf *, const char *, uint32_t);