Function change_route_nhop

freebsd/net/route/route_ctl.c:1099–1145

* Switch @rt nhop/weigh to the ones specified in @rnd. * Conditionally set rt_expire if set in @info. * Returns 0 on success. */

 * Returns 0 on success.
 */
int
change_route_nhop(struct rib_head *rnh, struct rtentry *rt,
    struct rt_addrinfo *info, struct route_nhop_data *rnd,
    struct rib_cmd_info *rc)
{
	struct nhop_object *nh_orig;

	RIB_WLOCK_ASSERT(rnh);

	nh_orig = rt->rt_nhop;

	if (rnd->rnd_nhop != NULL) {
		/* Changing expiration & nexthop & weight to a new one */
		rt_set_expire_info(rt, info);
		rt->rt_nhop = rnd->rnd_nhop;
		rt->rt_weight = rnd->rnd_weight;
		if (rt->rt_expire > 0)
			tmproutes_update(rnh, rt);
	} else {
		/* Route deletion requested. */
		struct sockaddr *ndst, *netmask;
		struct radix_node *rn;

		ndst = (struct sockaddr *)rt_key(rt);
		netmask = info->rti_info[RTAX_NETMASK];
		rn = rnh->rnh_deladdr(ndst, netmask, &rnh->head);
		if (rn == NULL)
			return (ESRCH);
		rt = RNTORT(rn);
		rt->rte_flags &= ~RTF_UP;
	}

	/* Finalize notification */
	rnh->rnh_gen++;
	if (rnd->rnd_nhop == NULL)
		rnh->rnh_prefixes--;

	rc->rc_cmd = (rnd->rnd_nhop != NULL) ? RTM_CHANGE : RTM_DELETE;
	rc->rc_rt = rt;
	rc->rc_nh_old = nh_orig;
	rc->rc_nh_new = rnd->rnd_nhop;
	rc->rc_nh_weight = rnd->rnd_weight;

	rib_notify(rnh, RIB_NOTIFY_IMMEDIATE, rc);

	return (0);
}

/*
 * Conditionally update route nhop/weight IFF data in @nhd_orig is