From e7ff02539c22d6fde61844640bc1659e8588c09b Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Thu, 20 Aug 2020 14:42:56 -0400
Subject: [PATCH] lib: Note old ifindex on shutdown

If we have an interface configured in a daemon on shutdown
store the old ifindex value for retrieval on when it is
possibly recreated.

This is especially important for nexthop groups as that we
had at one point in time the ability to restore the
configuration but it was lost when we started deleting
all deleted interfaces.  We need the nexthop group subsystem
to also mark that it has configured an interface.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
---
 lib/if.c            | 2 ++
 lib/if.h            | 2 ++
 lib/nexthop_group.c | 7 +++++++
 lib/zclient.c       | 2 +-
 4 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/if.c b/lib/if.c
index d8392708e1..10db574dc4 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -188,7 +188,9 @@ void if_destroy_via_zapi(struct interface *ifp)
 	if (ifp_master.destroy_hook)
 		(*ifp_master.destroy_hook)(ifp);
 
+	ifp->oldifindex = ifp->ifindex;
 	if_set_index(ifp, IFINDEX_INTERNAL);
+
 	if (!ifp->configured)
 		if_delete(&ifp);
 }
diff --git a/lib/if.h b/lib/if.h
index 1fb0757db2..a2a40d0957 100644
--- a/lib/if.h
+++ b/lib/if.h
@@ -224,6 +224,8 @@ struct interface {
 	   not work as expected.
 	 */
 	ifindex_t ifindex;
+	ifindex_t oldifindex;
+
 	/*
 	 * ifindex of parent interface, if any
 	 */
diff --git a/lib/nexthop_group.c b/lib/nexthop_group.c
index a8f6e8a405..687cac4062 100644
--- a/lib/nexthop_group.c
+++ b/lib/nexthop_group.c
@@ -940,6 +940,12 @@ DEFPY(ecmp_nexthops, ecmp_nexthops_cmd,
 			nhg_hooks.add_nexthop(nhgc, nh);
 	}
 
+	if (intf) {
+		struct interface *ifp = if_lookup_by_name_all_vrf(intf);
+
+		if (ifp)
+			ifp->configured = true;
+	}
 	return CMD_SUCCESS;
 }
 
@@ -1242,6 +1248,7 @@ void nexthop_group_interface_state_change(struct interface *ifp,
 				if (ifp->ifindex != nhop.ifindex)
 					continue;
 
+				ifp->configured = true;
 				nh = nexthop_new();
 
 				memcpy(nh, &nhop, sizeof(nhop));
diff --git a/lib/zclient.c b/lib/zclient.c
index 6b5f3e349a..b842e7c31b 100644
--- a/lib/zclient.c
+++ b/lib/zclient.c
@@ -2068,7 +2068,7 @@ static void zebra_interface_if_set_value(struct stream *s,
 	uint8_t link_params_status = 0;
 	ifindex_t old_ifindex, new_ifindex;
 
-	old_ifindex = ifp->ifindex;
+	old_ifindex = ifp->oldifindex;
 	/* Read interface's index. */
 	STREAM_GETL(s, new_ifindex);
 	if_set_index(ifp, new_ifindex);