ospf6d: fix loop in ABRs

When two routers from same area connected to backbone,
intra route advertised from area x should take precedence
within area x. The same route would be injected as summary
lsa to area 0/y. The same LSA via second abr injected back to
area x and since area 0 is lower than area x its route take
precedence.
Move the area check below path type and cost as both are crucial
to determine best route.

Ticket:CM-19627
Testing Done:
Initial route generated via area 1 as Intra-Prefix LSA (2009).
R1 and R2 both re advertised Inter Area Prefix LSA
(Summary LSA 2003) to area 1.
With the change area 1 Intra route precedence is preserved.
The address of H1 from Right is reachable via ping.

     area 1 |  area 0
            R1
          /   \
         /     \
        /       \
  H1 --Left     Right
        \       /
         \     /
          \   /
            R2
     area 1 |  area 0

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>

3 files changed, 14 insertions, 7 deletions

diff --git a/ospf6d/ospf6_abr.c b/ospf6d/ospf6_abr.c
index 163f2dbff..01b8055b6 100644
--- a/ospf6d/ospf6_abr.c
+++ b/ospf6d/ospf6_abr.c
@@ -695,6 +695,7 @@ void ospf6_abr_examin_summary(struct ospf6_lsa *lsa, struct ospf6_area *oa)
 	int is_debug = 0;
 	struct ospf6_inter_prefix_lsa *prefix_lsa = NULL;
 	struct ospf6_inter_router_lsa *router_lsa = NULL;
+	struct ospf6_path *path;
 
 	memset(&prefix, 0, sizeof(prefix));
 
@@ -900,6 +901,9 @@ void ospf6_abr_examin_summary(struct ospf6_lsa *lsa, struct ospf6_area *oa)
 
 	ospf6_route_copy_nexthops(route, abr_entry);
 
+	path = ospf6_path_dup(&route->path);
+	ospf6_copy_nexthops(path->nh_list, abr_entry->nh_list);
+	listnode_add_sort(route->paths, path);
 
 	/* (7) If the routes are identical, copy the next hops over to existing
 	   route. ospf6's route table implementation will otherwise string both
diff --git a/ospf6d/ospf6_intra.c b/ospf6d/ospf6_intra.c
index 1872c6bd3..581a899bc 100644
--- a/ospf6d/ospf6_intra.c
+++ b/ospf6d/ospf6_intra.c
@@ -1326,6 +1326,7 @@ void ospf6_intra_prefix_lsa_add(struct ospf6_lsa *lsa)
 	char buf[PREFIX2STR_BUFFER];
 	struct interface *ifp;
 	int direct_connect = 0;
+	struct ospf6_path *path;
 
 	if (OSPF6_LSA_IS_MAXAGE(lsa))
 		return;
@@ -1417,9 +1418,14 @@ void ospf6_intra_prefix_lsa_add(struct ospf6_lsa *lsa)
 			ospf6_route_copy_nexthops(route, ls_entry);
 		}
 
+		path = ospf6_path_dup(&route->path);
+		ospf6_copy_nexthops(path->nh_list, route->path.nh_list);
+		listnode_add_sort(route->paths, path);
+
 		if (IS_OSPF6_DEBUG_EXAMIN(INTRA_PREFIX)) {
 			prefix2str(&route->prefix, buf, sizeof(buf));
-			zlog_debug("  route %s add with nh count %u", buf,
+			zlog_debug("  route %s add with cost %u nh count %u",
+				   buf, route->path.cost,
 				   listcount(route->nh_list));
 		}
 
@@ -1735,9 +1741,6 @@ void ospf6_intra_brouter_calculation(struct ospf6_area *oa)
 		    && CHECK_FLAG(brouter->flag, OSPF6_ROUTE_ADD)) {
 			UNSET_FLAG(brouter->flag, OSPF6_ROUTE_REMOVE);
 			UNSET_FLAG(brouter->flag, OSPF6_ROUTE_ADD);
-			zlog_debug("%s: EVENT unset REOUTE_REMOVE and ROUTE_ADD brouter %s",
-				   __PRETTY_FUNCTION__, brouter_name);
-			ospf6_brouter_debug_print(brouter);
 		}
 
 		if (CHECK_FLAG(brouter->flag, OSPF6_ROUTE_REMOVE)) {
diff --git a/ospf6d/ospf6_route.c b/ospf6d/ospf6_route.c
index 4d436792d..67b9b9df9 100644
--- a/ospf6d/ospf6_route.c
+++ b/ospf6d/ospf6_route.c
@@ -460,9 +460,6 @@ int ospf6_route_cmp(struct ospf6_route *ra, struct ospf6_route *rb)
 	if (ra->type != rb->type)
 		return (ra->type - rb->type);
 
-	if (ra->path.area_id != rb->path.area_id)
-		return (ntohl(ra->path.area_id) - ntohl(rb->path.area_id));
-
 	if (ra->path.type != rb->path.type)
 		return (ra->path.type - rb->path.type);
 
@@ -476,6 +473,9 @@ int ospf6_route_cmp(struct ospf6_route *ra, struct ospf6_route *rb)
 			return (ra->path.cost - rb->path.cost);
 	}
 
+	if (ra->path.area_id != rb->path.area_id)
+		return (ntohl(ra->path.area_id) - ntohl(rb->path.area_id));
+
 	return 0;
 }