bridge_ip
m = bridge_ip(&sc->sc_if, BRIDGE_IN, src_if, &eh, m);
m = bridge_ip(&sc->sc_if, BRIDGE_OUT, dst_if, &eh, m);
struct mbuf *bridge_ip(struct ifnet *, int, struct ifnet *,
mc = bridge_ip(&sc->sc_if, BRIDGE_OUT, dst_if, eh, mc);