staticd: fix changing to source auto in bfd monitor

When monitoring a static route with BFD multi-hop, the source IP can be
either configured or retrieved from NextHop-Tracking (NHT). After
removing a configured source, the source is supposed to be retrieved
from NHT but it remains to the previous value. This is problematic if
the user desires to fix the configuration of a incorrect source IP.

For example, theses two commands results in the incorrect state:

> ip route 10.0.0.0/24 10.1.0.1 bfd multi-hop source 10.2.2.2
> ip route 10.0.0.0/24 10.1.0.1 bfd multi-hop

When removing the source, BFD is unable to find the source from NHT via
bfd_nht_update() were called.

Force zebra to resend the information to BFD by unregistering and
registering again NHT. The (...)/frr-nexthops/nexthop northbound
apply_finish function will trigger a call to static_install_nexthop()
that does a call to static_zebra_nht_register(nh, true);

Fixes: b7ca809d1c ("lib: BFD automatic source selection")
Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>
(cherry picked from commit 580c605194b3893a1d61a997a7b9d62e2d877427)

diff --git a/staticd/static_nb_config.c b/staticd/static_nb_config.c
index ede2e387544c5f6fa6e4a2b3ab1abee258c82bfa..8a497304a81e442344d7c7d5f4bf2cbff404d8a3 100644 (file)
--- a/staticd/static_nb_config.c
+++ b/staticd/static_nb_config.c
@@ -18,6 +18,7 @@
 #include "static_vrf.h"
 #include "static_routes.h"
 #include "static_nb.h"
+#include "static_zebra.h"
 
 
 static int static_path_list_create(struct nb_cb_create_args *args)
@@ -960,6 +961,17 @@ int route_next_hop_bfd_source_destroy(struct nb_cb_destroy_args *args)
 
        sn = nb_running_get_entry(args->dnode, NULL, true);
        static_next_hop_bfd_auto_source(sn);
+
+       /* NHT information are needed by BFD to automatically find the source
+        *
+        * Force zebra to resend the information to BFD by unregistering and
+        * registering again NHT. The (...)/frr-nexthops/nexthop northbound
+        * apply_finish function will trigger a call to static_install_nexthop()
+        * that does a call to static_zebra_nht_register(nh, true);
+        * static_zebra_nht_register(sn, false);
+        */
+       static_zebra_nht_register(sn, false);
+
        return NB_OK;
 }