Function ifpromisc

freebsd/net/if.c:3176–3190

* Set/clear promiscuous mode on interface ifp based on the truth value * of pswitch. The calls are reference counted so that only the first * "on" request actually has an effect, as does the final "off" request. * Results are undefined if the "off" and "on" requests are not matched. */

 * Results are undefined if the "off" and "on" requests are not matched.
 */
int
ifpromisc(struct ifnet *ifp, int pswitch)
{
	int error;
	int oldflags = ifp->if_flags;

	error = if_setflag(ifp, IFF_PROMISC, IFF_PPROMISC,
			   &ifp->if_pcount, pswitch);
	/* If promiscuous mode status has changed, log a message */
	if (error == 0 && ((ifp->if_flags ^ oldflags) & IFF_PROMISC) &&
            log_promisc_mode_change)
		if_printf(ifp, "promiscuous mode %s\n",
		    (ifp->if_flags & IFF_PROMISC) ? "enabled" : "disabled");
	return (error);
}

/*
 * Return interface configuration