rn_lookup
ke = (struct pfr_kentry *)rn_lookup(&sa, &mask, head);
ke = (struct pfr_kentry *)rn_lookup(&key->pfrke_sa, &mask,
session = (struct pipex_session *)rn_lookup(&pipex_in4, &pipex_in4mask,
struct radix_node *rn_lookup(void *, void *, struct radix_node_head *);