/* Gateway selection by Hash-Threshold (RFC 2992) */
struct rtentry *
rn_mpath_select(struct rtentry *rt, uint32_t *srcaddrp)
{
struct radix_node *rn;
int hash, npaths, threshold;
rn = (struct radix_node *)rt;
npaths = rn_mpath_active_count(rn);
hash = rn_mpath_hash(rt_key(rt), srcaddrp) & 0xffff;
threshold = 1 + (0xffff / npaths);
while (hash > threshold && rn) {
/* stay within the multipath routes */
rn = rn_mpath_next(rn, RMP_MODE_ACTIVE);
hash -= threshold;
}
/* if gw selection fails, use the first match (default) */
if (rn != NULL) {
rtfree(rt);
rt = (struct rtentry *)rn;
rt->rt_refcnt++;
}
return (rt);
}
/*
* allocate a route, potentially using multipath to select the peer.
*/
void
rtalloc_mpath(struct route *ro, u_int32_t *srcaddrp)
{
#if defined(INET) || defined(INET6)
struct radix_node *rn;
int hash, npaths, threshold;
#endif
/*
* return a cached entry if it is still valid, otherwise we increase
* the risk of disrupting local flows.
*/
if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP))
return;
ro->ro_rt = rtalloc1(&ro->ro_dst, RT_REPORT, ro->ro_tableid);
/* if the route does not exist or it is not multipath, don't care */
if (!ro->ro_rt || !(ro->ro_rt->rt_flags & RTF_MPATH))
return;
/* check if multipath routing is enabled for the specified protocol */
if (!(0
#ifdef INET
|| (ipmultipath && ro->ro_dst.sa_family == AF_INET)
#endif
#ifdef INET6
|| (ip6_multipath && ro->ro_dst.sa_family == AF_INET6)
#endif
))
return;
#if defined(INET) || defined(INET6)
/* gw selection by Hash-Threshold (RFC 2992) */
rn = (struct radix_node *)ro->ro_rt;
npaths = rn_mpath_count(rn);
hash = rn_mpath_hash(ro, srcaddrp) & 0xffff;
threshold = 1 + (0xffff / npaths);
while (hash > threshold && rn) {
/* stay within the multipath routes */
if (rn_mpath_next(rn, 0) == NULL)
break;
rn = rn->rn_dupedkey;
hash -= threshold;
}
/* XXX try filling rt_gwroute and avoid unreachable gw */
/* if gw selection fails, use the first match (default) */
if (!rn)
return;
rtfree(ro->ro_rt);
ro->ro_rt = (struct rtentry *)rn;
ro->ro_rt->rt_refcnt++;
#endif
}
