netif_get
n = netif_get(d, eh, len, tleft);
if (drv->netif_get == NULL)
rv = drv->netif_get(desc, pkt, len, timo);
int (*netif_get)(struct iodesc *, void *, size_t, time_t);
ssize_t netif_get(struct iodesc *, void *, size_t, time_t);