From 3a94ed56964097e35c932bafce0c164b9323c12d Mon Sep 17 00:00:00 2001
From: Renato Westphal <renato@opensourcerouting.org>
Date: Wed, 1 Mar 2023 17:31:56 -0300
Subject: [PATCH] ospf6d: fix duplicate inter-area-prefix-LSAs after exiting
 from GR mode

An ABR that is originating inter-area-prefix-LSAs should take into
account the fact that there might be self-originated LSAs for the
same prefixes that were originated prior to a graceful restart. When
that happens, the previous LSA-IDs should be reused to avoid having
duplicate LSAs.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>
---
 ospf6d/ospf6_abr.c  | 16 +++++++++++++---
 ospf6d/ospf6_lsdb.c | 27 +++++++++++++++++++++++++++
 ospf6d/ospf6_lsdb.h |  3 +++
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/ospf6d/ospf6_abr.c b/ospf6d/ospf6_abr.c
index 4def3c7386..5b2b204dd8 100644
--- a/ospf6d/ospf6_abr.c
+++ b/ospf6d/ospf6_abr.c
@@ -515,11 +515,21 @@ int ospf6_abr_originate_summary_to_area(struct ospf6_route *route,
 			summary->path.origin.id =
 				ADV_ROUTER_IN_PREFIX(&route->prefix);
 		} else {
+			struct ospf6_lsa *old;
+
 			summary->path.origin.type =
 				htons(OSPF6_LSTYPE_INTER_PREFIX);
-			summary->path.origin.id = ospf6_new_ls_id(
-				summary->path.origin.type,
-				summary->path.origin.adv_router, area->lsdb);
+
+			/* Try to reuse LS-ID from previous running instance. */
+			old = ospf6_find_inter_prefix_lsa(area->ospf6, area,
+							  &route->prefix);
+			if (old)
+				summary->path.origin.id = old->header->id;
+			else
+				summary->path.origin.id = ospf6_new_ls_id(
+					summary->path.origin.type,
+					summary->path.origin.adv_router,
+					area->lsdb);
 		}
 		summary = ospf6_route_add(summary, summary_table);
 	} else {
diff --git a/ospf6d/ospf6_lsdb.c b/ospf6d/ospf6_lsdb.c
index 0221102b59..586183731c 100644
--- a/ospf6d/ospf6_lsdb.c
+++ b/ospf6d/ospf6_lsdb.c
@@ -13,8 +13,10 @@
 #include "vty.h"
 
 #include "ospf6_proto.h"
+#include "ospf6_area.h"
 #include "ospf6_lsa.h"
 #include "ospf6_lsdb.h"
+#include "ospf6_abr.h"
 #include "ospf6_asbr.h"
 #include "ospf6_route.h"
 #include "ospf6d.h"
@@ -216,6 +218,31 @@ struct ospf6_lsa *ospf6_find_external_lsa(struct ospf6 *ospf6, struct prefix *p)
 	return lsa;
 }
 
+struct ospf6_lsa *ospf6_find_inter_prefix_lsa(struct ospf6 *ospf6,
+					      struct ospf6_area *area,
+					      struct prefix *p)
+{
+	struct ospf6_lsa *lsa;
+	uint16_t type = htons(OSPF6_LSTYPE_INTER_PREFIX);
+
+	for (ALL_LSDB_TYPED_ADVRTR(area->lsdb, type, ospf6->router_id, lsa)) {
+		struct ospf6_inter_prefix_lsa *prefix_lsa;
+		struct prefix prefix;
+
+		prefix_lsa =
+			(struct ospf6_inter_prefix_lsa *)OSPF6_LSA_HEADER_END(
+				lsa->header);
+		prefix.family = AF_INET6;
+		prefix.prefixlen = prefix_lsa->prefix.prefix_length;
+		ospf6_prefix_in6_addr(&prefix.u.prefix6, prefix_lsa,
+				      &prefix_lsa->prefix);
+		if (prefix_same(p, &prefix))
+			return lsa;
+	}
+
+	return NULL;
+}
+
 struct ospf6_lsa *ospf6_lsdb_lookup_next(uint16_t type, uint32_t id,
 					 uint32_t adv_router,
 					 struct ospf6_lsdb *lsdb)
diff --git a/ospf6d/ospf6_lsdb.h b/ospf6d/ospf6_lsdb.h
index 7e20b05447..a2444f1c14 100644
--- a/ospf6d/ospf6_lsdb.h
+++ b/ospf6d/ospf6_lsdb.h
@@ -29,6 +29,9 @@ extern struct ospf6_lsa *ospf6_lsdb_lookup(uint16_t type, uint32_t id,
 extern struct ospf6_lsa *ospf6_lsdb_lookup_next(uint16_t type, uint32_t id,
 						uint32_t adv_router,
 						struct ospf6_lsdb *lsdb);
+extern struct ospf6_lsa *ospf6_find_inter_prefix_lsa(struct ospf6 *ospf6,
+						     struct ospf6_area *area,
+						     struct prefix *p);
 
 extern void ospf6_lsdb_add(struct ospf6_lsa *lsa, struct ospf6_lsdb *lsdb);
 extern void ospf6_lsdb_remove(struct ospf6_lsa *lsa, struct ospf6_lsdb *lsdb);