Function ia_getrtprefix

freebsd/netinet/in.c:829–847

* Calculate "prefix" route corresponding to @ia. */

 * Calculate "prefix" route corresponding to @ia.
 */
static void
ia_getrtprefix(const struct in_ifaddr *ia, struct in_addr *prefix, struct in_addr *mask)
{

	if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) {
		/* Case 3: return host route for dstaddr */
		*prefix = ia->ia_dstaddr.sin_addr;
		mask->s_addr = INADDR_BROADCAST;
	} else if (ia->ia_ifp->if_flags & IFF_LOOPBACK) {
		/* Case 4: return host route for ifaddr */
		*prefix = ia->ia_addr.sin_addr;
		mask->s_addr = INADDR_BROADCAST;
	} else {
		/* Cases 1,2: return actual ia prefix */
		*prefix = ia->ia_addr.sin_addr;
		*mask = ia->ia_sockmask.sin_addr;
		prefix->s_addr &= mask->s_addr;
	}
}

/*
 * Adds or delete interface "prefix" route corresponding to @ifa.