Function rib_change_route

freebsd/net/route/route_ctl.c:860–920

}

int
rib_change_route(uint32_t fibnum, struct rt_addrinfo *info,
    struct rib_cmd_info *rc)
{
	RIB_RLOCK_TRACKER;
	struct route_nhop_data rnd_orig;
	struct rib_head *rnh;
	struct rtentry *rt;
	int error;

	NET_EPOCH_ASSERT();

	rnh = get_rnh(fibnum, info);
	if (rnh == NULL)
		return (EAFNOSUPPORT);

	bzero(rc, sizeof(struct rib_cmd_info));
	rc->rc_cmd = RTM_CHANGE;

	/* Check if updated gateway exists */
	if ((info->rti_flags & RTF_GATEWAY) &&
	    (info->rti_info[RTAX_GATEWAY] == NULL)) {

		/*
		 * route(8) adds RTF_GATEWAY flag if -interface is not set.
		 * Remove RTF_GATEWAY to enforce consistency and maintain
		 * compatibility..
		 */
		info->rti_flags &= ~RTF_GATEWAY;
	}

	/*
	 * route change is done in multiple steps, with dropping and
	 * reacquiring lock. In the situations with multiple processes
	 * changes the same route in can lead to the case when route
	 * is changed between the steps. Address it by retrying the operation
	 * multiple times before failing.
	 */

	RIB_RLOCK(rnh);
	rt = (struct rtentry *)rnh->rnh_lookup(info->rti_info[RTAX_DST],
	    info->rti_info[RTAX_NETMASK], &rnh->head);

	if (rt == NULL) {
		RIB_RUNLOCK(rnh);
		return (ESRCH);
	}

	rnd_orig.rnd_nhop = rt->rt_nhop;
	rnd_orig.rnd_weight = rt->rt_weight;

	RIB_RUNLOCK(rnh);

	for (int i = 0; i < RIB_MAX_RETRIES; i++) {
		error = change_route(rnh, info, &rnd_orig, rc);
		if (error != EAGAIN)
			break;
	}