ospf6d: fix intra prefix ecmp

When there are multiple advertisers/paths to reach
Intra-Prefix route, if any path is removed,
re-added back, it does add to the same route node.

ospf6 intra prefix, first stored in oa->route_table
then as part of add cb, it would add to ospf6->route_table
which adds to FIB.

When copying a route with its paths & NHs from oa->table to
ospf6->table the path origin should not be modified otherwise
ospf6->table would not find existing node rather it appends
new node.

Use spf_table to fetch nexthops for a given advertisers/path,
to form effective nexthop list for a route.

Ticket:CM-16139
Testing Done:
    R2 ---- R3
     |       |
    R1 ---- R4
Inject Intra Ara Prefix LSA from R1 & R3, validate R2 and R4
having two origination point/paths to reach for a route.
Trigger link flap, frr restart or remove/readd R3's INP one of the
injection point.
Remove link between R4 to R1 and validate R3 carrying single
path to reach prefix.

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

1 files changed, 7 insertions, 4 deletions

diff --git a/ospf6d/ospf6_route.c b/ospf6d/ospf6_route.c
index 8be00d9b41..39272b3701 100644
--- a/ospf6d/ospf6_route.c
+++ b/ospf6d/ospf6_route.c
@@ -611,9 +611,10 @@ struct ospf6_route *ospf6_route_add(struct ospf6_route *route,
 		prefix2str(&route->prefix, buf, sizeof(buf));
 
 	if (IS_OSPF6_DEBUG_ROUTE(MEMORY))
-		zlog_debug("%s %p: route add %p: %s",
+		zlog_debug("%s %p: route add %p: %s paths %u nh %u",
 			   ospf6_route_table_name(table), (void *)table,
-			   (void *)route, buf);
+			   (void *)route, buf, listcount(route->paths),
+			   listcount(route->nh_list));
 	else if (IS_OSPF6_DEBUG_ROUTE(TABLE))
 		zlog_debug("%s: route add: %s", ospf6_route_table_name(table),
 			   buf);
@@ -664,11 +665,13 @@ struct ospf6_route *ospf6_route_add(struct ospf6_route *route,
 
 		if (IS_OSPF6_DEBUG_ROUTE(MEMORY))
 			zlog_debug(
-				"%s %p: route add %p cost %u nh %u: update of %p old cost %u nh %u",
+				"%s %p: route add %p cost %u paths %u nh %u: update of %p cost %u paths %u nh %u",
 				ospf6_route_table_name(table), (void *)table,
 				(void *)route, route->path.cost,
+				listcount(route->paths),
 				listcount(route->nh_list), (void *)old,
-				old->path.cost, listcount(old->nh_list));
+				old->path.cost, listcount(old->paths),
+				listcount(old->nh_list));
 		else if (IS_OSPF6_DEBUG_ROUTE(TABLE))
 			zlog_debug("%s: route add: update",
 				   ospf6_route_table_name(table));