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zebra: fix resolving nexthop through itself
Problems reported with zebra nht oscillating when a nexthop is resolved using the same address to reach the nexthop (for example, 10.0.0.8 is resolved via 10.0.0.8/32.) This fix removes this attempt to resolve thru itself unless the route being resolved is also a host route. This fix also walks up the tree looking for a less specific route to reach the nexthop if needed. Smoke testing completed successfully. Ticket: CM-8192 Signed-off-by: Don Slice <dslice@cumulusnetworks.com> Reviewed-by: CCR-6583 Testing done: Manual testing successful, bgp-min completed successfully l3-smoke completed with two test changes required.
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Don Slice
parent
0db8196a96
commit
fd7fd9e5c4
@ -449,9 +449,15 @@ static int nexthop_active(afi_t afi, struct route_entry *re,
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while (rn) {
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route_unlock_node(rn);
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/* If lookup self prefix return immediately. */
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if (rn == top)
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return 0;
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/* Lookup should halt if we've matched against ourselves ('top',
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* if specified) - i.e., we cannot have a nexthop NH1 is
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* resolved by a route NH1. The exception is if the route is a
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* host route.
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*/
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if (top && rn == top)
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if (((afi == AFI_IP) && (rn->p.prefixlen != 32)) ||
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((afi == AFI_IP6) && (rn->p.prefixlen != 128)))
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return 0;
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/* Pick up selected route. */
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/* However, do not resolve over default route unless explicitly
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@ -370,10 +370,12 @@ static int zebra_rnh_apply_nht_rmap(int family, struct route_node *prn,
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}
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/*
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* Determine appropriate route (RE entry) resolving a tracked entry
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* (nexthop or BGP route for import).
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* Determine appropriate route (RE entry) resolving a tracked BGP route
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* for BGP route for import.
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*/
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static struct route_entry *zebra_rnh_resolve_entry(vrf_id_t vrfid, int family,
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static
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struct route_entry *zebra_rnh_resolve_import_entry(vrf_id_t vrfid,
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int family,
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rnh_type_t type,
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struct route_node *nrn,
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struct rnh *rnh,
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@ -393,48 +395,25 @@ static struct route_entry *zebra_rnh_resolve_entry(vrf_id_t vrfid, int family,
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if (!rn)
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return NULL;
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/* Unlock route node - we don't need to lock when walking the tree. */
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route_unlock_node(rn);
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/* When resolving nexthops, do not resolve via the default route unless
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* 'ip nht resolve-via-default' is configured.
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*/
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if ((type == RNH_NEXTHOP_TYPE)
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&& (is_default_prefix(&rn->p)
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&& !nh_resolve_via_default(rn->p.family)))
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re = NULL;
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else if ((type == RNH_IMPORT_CHECK_TYPE)
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&& CHECK_FLAG(rnh->flags, ZEBRA_NHT_EXACT_MATCH)
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&& !prefix_same(&nrn->p, &rn->p))
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re = NULL;
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else {
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/* Identify appropriate route entry. */
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RNODE_FOREACH_RE (rn, re) {
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if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
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continue;
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if (!CHECK_FLAG(re->status, ROUTE_ENTRY_SELECTED_FIB))
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continue;
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if (((is_default_prefix(&rn->p)) ||
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((CHECK_FLAG(rnh->flags, ZEBRA_NHT_EXACT_MATCH)) &&
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!prefix_same(&nrn->p, &rn->p))))
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return NULL;
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if (CHECK_FLAG(rnh->flags, ZEBRA_NHT_CONNECTED)) {
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if (re->type == ZEBRA_ROUTE_CONNECT)
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break;
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if (re->type == ZEBRA_ROUTE_NHRP) {
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struct nexthop *nexthop;
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for (nexthop = re->nexthop; nexthop;
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nexthop = nexthop->next)
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if (nexthop->type
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== NEXTHOP_TYPE_IFINDEX)
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break;
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if (nexthop)
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break;
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}
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} else if ((type == RNH_IMPORT_CHECK_TYPE)
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&& (re->type == ZEBRA_ROUTE_BGP))
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continue;
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else
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break;
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}
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/* Identify appropriate route entry. */
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RNODE_FOREACH_RE(rn, re) {
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if (!CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED) &&
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CHECK_FLAG(re->flags, ZEBRA_FLAG_SELECTED) &&
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(re->type != ZEBRA_ROUTE_BGP))
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break;
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}
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/* Need to unlock route node */
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route_unlock_node(rn);
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if (re)
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*prn = rn;
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return re;
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@ -650,6 +629,86 @@ static void zebra_rnh_process_static_routes(vrf_id_t vrfid, int family,
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}
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}
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/*
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* Determine appropriate route (route entry) resolving a tracked
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* nexthop.
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*/
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static struct route_entry *zebra_rnh_resolve_nexthop_entry(vrf_id_t vrfid,
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int family,
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struct route_node *nrn,
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struct rnh *rnh,
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struct route_node **prn)
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{
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struct route_table *route_table;
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struct route_node *rn;
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struct route_entry *re;
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*prn = NULL;
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route_table = zebra_vrf_table(family2afi(family), SAFI_UNICAST, vrfid);
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if (!route_table)
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return NULL;
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rn = route_node_match(route_table, &nrn->p);
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if (!rn)
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return NULL;
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/* Unlock route node - we don't need to lock when walking the tree. */
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route_unlock_node(rn);
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/* While resolving nexthops, we may need to walk up the tree from the
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* most-specific match. Do similar logic as in zebra_rib.c
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*/
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while (rn) {
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/* Do not resolve over default route unless allowed &&
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* match route to be exact if so specified
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*/
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if (is_default_prefix(&rn->p) &&
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!nh_resolve_via_default(rn->p.family))
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return NULL;
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/* Identify appropriate route entry. */
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RNODE_FOREACH_RE(rn, re) {
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if (CHECK_FLAG(re->status, ROUTE_ENTRY_REMOVED))
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continue;
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if (!CHECK_FLAG(re->flags, ZEBRA_FLAG_SELECTED))
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continue;
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if (CHECK_FLAG(rnh->flags, ZEBRA_NHT_CONNECTED)) {
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if ((re->type == ZEBRA_ROUTE_CONNECT)
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|| (re->type == ZEBRA_ROUTE_STATIC))
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break;
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if (re->type == ZEBRA_ROUTE_NHRP) {
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struct nexthop *nexthop;
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for (nexthop = re->nexthop;
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nexthop;
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nexthop = nexthop->next)
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if (nexthop->type
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== NEXTHOP_TYPE_IFINDEX)
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break;
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if (nexthop)
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break;
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}
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} else
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break;
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}
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/* Route entry found, we're done; else, walk up the tree. */
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if (re) {
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*prn = rn;
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return re;
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}
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if (CHECK_FLAG(rnh->flags, ZEBRA_NHT_CONNECTED))
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rn = rn->parent;
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else
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return NULL;
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}
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return NULL;
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}
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static void zebra_rnh_process_pseudowires(vrf_id_t vrfid, struct rnh *rnh)
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{
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struct zebra_pw *pw;
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@ -724,7 +783,12 @@ static void zebra_rnh_evaluate_entry(vrf_id_t vrfid, int family, int force,
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rnh = nrn->info;
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/* Identify route entry (RE) resolving this tracked entry. */
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re = zebra_rnh_resolve_entry(vrfid, family, type, nrn, rnh, &prn);
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if (type == RNH_IMPORT_CHECK_TYPE)
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re = zebra_rnh_resolve_import_entry(vrfid, family, type, nrn,
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rnh, &prn);
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else
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re = zebra_rnh_resolve_nexthop_entry(vrfid, family, nrn, rnh,
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&prn);
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/* If the entry cannot be resolved and that is also the existing state,
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* there is nothing further to do.
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@ -759,7 +823,13 @@ static void zebra_rnh_clear_nhc_flag(vrf_id_t vrfid, int family,
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rnh = nrn->info;
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re = zebra_rnh_resolve_entry(vrfid, family, type, nrn, rnh, &prn);
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/* Identify route entry (RIB) resolving this tracked entry. */
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if (type == RNH_IMPORT_CHECK_TYPE)
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re = zebra_rnh_resolve_import_entry(vrfid, family, type, nrn,
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rnh, &prn);
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else
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re = zebra_rnh_resolve_nexthop_entry(vrfid, family, nrn, rnh,
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&prn);
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if (re) {
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UNSET_FLAG(re->status, ROUTE_ENTRY_NEXTHOPS_CHANGED);
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