ospf6d: Handle Premature Aging of LSAs

RFC 2328 (14.1) Premature aging of LSAs from
routing domain :
When ospf6d is going away (router going down),
send MAXAGEd self originated LSAs to all
neighbors in routing domain to trigger
Premature aging to remove from resepective LSDBs.

Neighbor Router Reboot:
Upon receiving Self-originate MAXAGEd LSA, simply
discard, Current copy could be non maxaged latest.

For neighbor advertised LSA's (current copy in LSDB)
is set to MAXAGE but received new LSA with Non-MAXAGE
(with current age), discard the current MAXAGE LSA,
Send latest copy of LSA to neighbors and update the
LSDB with new LSA.

When a neighbor transition to FULL, trigger AS-External
LSAs update from external LSDB to new neighbor.

Testing:
R1 ---- DUT --- R5
| \
R2 R3
|
R4

Area 1: R5 and DUT
Area 0: DUT, R1, R2, R3
Area 2: R2 R4

Add IPv6 static routes at R5
Redistribute kernel routes at R5,
Validate routes at R4, redistributed via backbone
to area 2.
Stop n start frr.service at R5 and validated
MAXAGE LSAs then recent age LSAs in Database at DUT-R4.
Validated external routes installed DUT to R4.

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

1 files changed, 59 insertions, 15 deletions

diff --git a/ospf6d/ospf6_flood.c b/ospf6d/ospf6_flood.c
index 42716fbc7..17733d609 100644
--- a/ospf6d/ospf6_flood.c
+++ b/ospf6d/ospf6_flood.c
@@ -192,10 +192,6 @@ void ospf6_install_lsa(struct ospf6_lsa *lsa)
 	struct timeval now;
 	struct ospf6_lsa *old;
 
-	if (IS_OSPF6_DEBUG_LSA_TYPE(lsa->header->type)
-	    || IS_OSPF6_DEBUG_EXAMIN_TYPE(lsa->header->type))
-		zlog_debug("Install LSA: %s", lsa->name);
-
 	/* Remove the old instance from all neighbors' Link state
 	   retransmission list (RFC2328 13.2 last paragraph) */
 	old = ospf6_lsdb_lookup(lsa->header->type, lsa->header->id,
@@ -237,6 +233,13 @@ void ospf6_install_lsa(struct ospf6_lsa *lsa)
 		ospf6_lsa_checksum(lsa->header);
 	}
 
+	if (IS_OSPF6_DEBUG_LSA_TYPE(lsa->header->type)
+	    || IS_OSPF6_DEBUG_EXAMIN_TYPE(lsa->header->type))
+		zlog_debug("%s Install LSA: %s age %d seqnum %x in LSDB.",
+			   __PRETTY_FUNCTION__, lsa->name,
+			   ntohs(lsa->header->age),
+			   ntohl(lsa->header->seqnum));
+
 	/* actually install */
 	lsa->installed = now;
 	ospf6_lsdb_add(lsa, lsa->lsdb);
@@ -246,7 +249,7 @@ void ospf6_install_lsa(struct ospf6_lsa *lsa)
 
 /* RFC2740 section 3.5.2. Sending Link State Update packets */
 /* RFC2328 section 13.3 Next step in the flooding procedure */
-static void ospf6_flood_interface(struct ospf6_neighbor *from,
+void ospf6_flood_interface(struct ospf6_neighbor *from,
 				  struct ospf6_lsa *lsa,
 				  struct ospf6_interface *oi)
 {
@@ -343,15 +346,24 @@ static void ospf6_flood_interface(struct ospf6_neighbor *from,
 			continue;
 		}
 
-		/* (d) add retrans-list, schedule retransmission */
-		if (is_debug)
-			zlog_debug("Add retrans-list of this neighbor");
-		ospf6_increment_retrans_count(lsa);
-		ospf6_lsdb_add(ospf6_lsa_copy(lsa), on->retrans_list);
-		thread_add_timer(master, ospf6_lsupdate_send_neighbor, on,
-				 on->ospf6_if->rxmt_interval,
-				 &on->thread_send_lsupdate);
-		retrans_added++;
+		if (ospf6->inst_shutdown) {
+			if (is_debug)
+				zlog_debug("%s: Send LSA %s (age %d) update now",
+					   __PRETTY_FUNCTION__, lsa->name,
+					   ntohs(lsa->header->age));
+			ospf6_lsupdate_send_neighbor_now(on, lsa);
+			continue;
+		} else {
+			/* (d) add retrans-list, schedule retransmission */
+			if (is_debug)
+				zlog_debug("Add retrans-list of this neighbor");
+			ospf6_increment_retrans_count(lsa);
+			ospf6_lsdb_add(ospf6_lsa_copy(lsa), on->retrans_list);
+			thread_add_timer(master, ospf6_lsupdate_send_neighbor,
+					 on, on->ospf6_if->rxmt_interval,
+					 &on->thread_send_lsupdate);
+			retrans_added++;
+		}
 	}
 
 	/* (2) examin next interface if not added to retrans-list */
@@ -806,6 +818,17 @@ void ospf6_receive_lsa(struct ospf6_neighbor *from,
 				zlog_debug("Received is duplicated LSA");
 			SET_FLAG(new->flag, OSPF6_LSA_DUPLICATE);
 		}
+		if (old->header->adv_router ==
+		    from->ospf6_if->area->ospf6->router_id
+		    && OSPF6_LSA_IS_MAXAGE(new)) {
+			ospf6_acknowledge_lsa(new, ismore_recent, from);
+			ospf6_lsa_delete(new);
+			if (is_debug)
+				zlog_debug("%s: Received is self orig MAXAGE LSA %s, discard (ismore_recent %d)",
+					   __PRETTY_FUNCTION__, old->name,
+					   ismore_recent);
+			return;
+		}
 	}
 
 	/* if no database copy or received is more recent */
@@ -959,12 +982,34 @@ void ospf6_receive_lsa(struct ospf6_neighbor *from,
 					"Send back directly and then discard");
 			}
 
+			/* Neighbor router sent recent age for LSA,
+			 * Router could be restarted while current copy is
+			 * MAXAGEd and not removed.*/
+			if (OSPF6_LSA_IS_MAXAGE(old) &&
+			    !OSPF6_LSA_IS_MAXAGE(new)) {
+
+				if (is_debug)
+					zlog_debug("%s: Current copy of LSA %s is MAXAGE, but new has recent Age.",
+						   old->name,
+					   __PRETTY_FUNCTION__);
+
+				ospf6_lsa_purge(old);
+				if (new->header->adv_router
+						!= from->ospf6_if->area->
+							ospf6->router_id)
+					ospf6_flood(from, new);
+
+				ospf6_install_lsa(new);
+				return;
+			}
+
 			/* XXX, MinLSArrival check !? RFC 2328 13 (8) */
 
 			ospf6_lsdb_add(ospf6_lsa_copy(old),
 				       from->lsupdate_list);
 			thread_add_event(master, ospf6_lsupdate_send_neighbor,
 					 from, 0, &from->thread_send_lsupdate);
+
 			ospf6_lsa_delete(new);
 			return;
 		}
@@ -972,7 +1017,6 @@ void ospf6_receive_lsa(struct ospf6_neighbor *from,
 	}
 }
 
-
 DEFUN (debug_ospf6_flooding,
        debug_ospf6_flooding_cmd,
        "debug ospf6 flooding",