zebra: Fix neighbor update to BGP

Ensure that when the is_router condition changes for a locally learnt
neighbor, it is informed to BGP only if it is active i.e., the MAC is
also locally learnt.

Signed-off-by: Vivek Venkatraman <vivek@cumulusnetworks.com>
Reviewed-by:   Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Reviewed-by:   Chirag Shah <chirag@cumulusnetworks.com>

Ticket: CM-22288
Reviewed By: CCR-7832
Testing Done:
1. Failed test
2. vxlan_routing_test.py

1 files changed, 48 insertions, 39 deletions

diff --git a/zebra/zebra_vxlan.c b/zebra/zebra_vxlan.c
index c6136dfa3..397bfaec9 100644
--- a/zebra/zebra_vxlan.c
+++ b/zebra/zebra_vxlan.c
@@ -2028,51 +2028,60 @@ static int zvni_local_neigh_update(zebra_vni_t *zvni,
 		check_rbit = true;
 	} else {
 		if (CHECK_FLAG(n->flags, ZEBRA_NEIGH_LOCAL)) {
-			/* If there is no MAC change, BGP isn't interested. */
-			if (is_router !=
-			    (CHECK_FLAG(n->flags, ZEBRA_NEIGH_ROUTER_FLAG)
-					? 1 : 0))
-				check_rbit = true;
-
-			if (memcmp(n->emac.octet, macaddr->octet,
-				   ETH_ALEN) == 0) {
-				/* Update any params and return - client doesn't
-				 * care about a purely local change.
-				 */
+			bool mac_different;
+			bool cur_is_router;
+
+			/* Note any changes and see if of interest to BGP. */
+			mac_different = (memcmp(n->emac.octet,
+					macaddr->octet, ETH_ALEN) != 0) ? 1 : 0;
+			cur_is_router = !!CHECK_FLAG(n->flags,
+						     ZEBRA_NEIGH_ROUTER_FLAG);
+			if (!mac_different && is_router == cur_is_router) {
 				n->ifindex = ifp->ifindex;
-			} else {
+				return 0;
+			}
 
-				/* If the MAC has changed, need to issue a
-				 * delete first as this means a different
-				 * MACIP route. Also, need to do some
-				 * unlinking/relinking. We also need to
-				 * update the MAC's sequence number
-				 * in different situations.
-				 */
-				if (IS_ZEBRA_NEIGH_ACTIVE(n))
-					zvni_neigh_send_del_to_client(
-						zvni->vni, &n->ip, &n->emac, 0);
-				old_zmac = zvni_mac_lookup(zvni, &n->emac);
-				if (old_zmac) {
-					old_mac_seq =
-						CHECK_FLAG(old_zmac->flags,
-							   ZEBRA_MAC_REMOTE) ?
-							old_zmac->rem_seq :
-							old_zmac->loc_seq;
-					neigh_mac_change = upd_mac_seq = true;
-					listnode_delete(
-						old_zmac->neigh_list, n);
-					zvni_deref_ip2mac(zvni, old_zmac);
-				}
+			if (!mac_different) {
+				/* Only the router flag has changed. */
+				if (is_router)
+					SET_FLAG(n->flags,
+						ZEBRA_NEIGH_ROUTER_FLAG);
+				else
+					UNSET_FLAG(n->flags,
+						ZEBRA_NEIGH_ROUTER_FLAG);
 
-				/* Update the forwarding info. */
-				n->ifindex = ifp->ifindex;
-				memcpy(&n->emac, macaddr, ETH_ALEN);
+				if (IS_ZEBRA_NEIGH_ACTIVE(n))
+					return zvni_neigh_send_add_to_client(
+							zvni->vni, ip, macaddr,
+							n->flags, n->loc_seq);
+				return 0;
+			}
 
-				/* Link to new MAC */
-				listnode_add_sort(zmac->neigh_list, n);
+			/* The MAC has changed, need to issue a delete
+			 * first as this means a different MACIP route.
+			 * Also, need to do some unlinking/relinking.
+			 * We also need to update the MAC's sequence number
+			 * in different situations.
+			 */
+			if (IS_ZEBRA_NEIGH_ACTIVE(n))
+				zvni_neigh_send_del_to_client(zvni->vni, &n->ip,
+							      &n->emac, 0);
+			old_zmac = zvni_mac_lookup(zvni, &n->emac);
+			if (old_zmac) {
+				old_mac_seq = CHECK_FLAG(old_zmac->flags,
+							 ZEBRA_MAC_REMOTE) ?
+					old_zmac->rem_seq : old_zmac->loc_seq;
+				neigh_mac_change = upd_mac_seq = true;
+				listnode_delete(old_zmac->neigh_list, n);
+				zvni_deref_ip2mac(zvni, old_zmac);
 			}
 
+			/* Update the forwarding info. */
+			n->ifindex = ifp->ifindex;
+			memcpy(&n->emac, macaddr, ETH_ALEN);
+
+			/* Link to new MAC */
+			listnode_add_sort(zmac->neigh_list, n);
 		} else if (CHECK_FLAG(n->flags, ZEBRA_NEIGH_REMOTE)) {
 			/*
 			 * Neighbor has moved from remote to local. Its