Function add_route

freebsd/net/route/route_ctl.c:650–721

}

static int
add_route(struct rib_head *rnh, struct rt_addrinfo *info,
    struct rib_cmd_info *rc)
{
	struct nhop_object *nh_orig;
	struct route_nhop_data rnd_orig, rnd_add;
	struct nhop_object *nh;
	struct rtentry *rt, *rt_orig;
	int error;

	error = create_rtentry(rnh, info, &rt);
	if (error != 0)
		return (error);

	rnd_add.rnd_nhop = rt->rt_nhop;
	rnd_add.rnd_weight = rt->rt_weight;
	nh = rt->rt_nhop;

	RIB_WLOCK(rnh);
	error = add_route_nhop(rnh, rt, info, &rnd_add, rc);
	if (error == 0) {
		RIB_WUNLOCK(rnh);
		return (0);
	}

	/* addition failed. Lookup prefix in the rib to determine the cause */
	rt_orig = lookup_prefix(rnh, info, &rnd_orig);
	if (rt_orig == NULL) {
		/* No prefix -> rnh_addaddr() failed to allocate memory */
		RIB_WUNLOCK(rnh);
		nhop_free(nh);
		uma_zfree(V_rtzone, rt);
		return (ENOMEM);
	}

	/* We have existing route in the RIB. */
	nh_orig = rnd_orig.rnd_nhop;
	/* Check if new route has higher preference */
	if (can_override_nhop(info, nh_orig) > 0) {
		/* Update nexthop to the new route */
		change_route_nhop(rnh, rt_orig, info, &rnd_add, rc);
		RIB_WUNLOCK(rnh);
		uma_zfree(V_rtzone, rt);
		nhop_free(nh_orig);
		return (0);
	}

	RIB_WUNLOCK(rnh);

#ifdef ROUTE_MPATH
	if (rib_can_multipath(rnh) && nhop_can_multipath(rnd_add.rnd_nhop) &&
	    nhop_can_multipath(rnd_orig.rnd_nhop))
		error = add_route_mpath(rnh, info, rt, &rnd_add, &rnd_orig, rc);
	else
#endif
	/* Unable to add - another route with the same preference exists */
	error = EEXIST;