lib: fix iteration over schema nodes of a single YANG module

The only safe way to iterate over all schema nodes of a given YANG
module is by iterating over all schema nodes of all YANG modules
and filter out the nodes that belong to other modules.

The original yang_snodes_iterate_module() code did the following:
1 - Iterate over all top-level schema nodes of the given module;
2 - Iterate over all augmentations of the given module.

While that iteration strategy is more efficient, it does't handle
well more complex YANG hierarchies containing nested augmentations
or self-augmenting modules. Any iteration that isn't done on the
resolved YANG data hierarchy is fragile and prone to errors.

Fixes regression introduced by commit 8a923b48513316b where the
gen_northbound_callbacks tool was generating duplicate callbacks
for certain modules.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/northbound_sysrepo.c b/lib/northbound_sysrepo.c
index 3cd310c5a..e9aac3ef1 100644
--- a/lib/northbound_sysrepo.c
+++ b/lib/northbound_sysrepo.c
@@ -575,6 +575,8 @@ static int frr_sr_subscribe_state(const struct lys_node *snode, void *arg)
 		return YANG_ITER_CONTINUE;
 
 	nb_node = snode->priv;
+	if (!nb_node)
+		return YANG_ITER_CONTINUE;
 
 	DEBUGD(&nb_dbg_client_sysrepo, "sysrepo: providing data to '%s'",
 	       nb_node->xpath);
@@ -599,6 +601,8 @@ static int frr_sr_subscribe_rpc(const struct lys_node *snode, void *arg)
 		return YANG_ITER_CONTINUE;
 
 	nb_node = snode->priv;
+	if (!nb_node)
+		return YANG_ITER_CONTINUE;
 
 	DEBUGD(&nb_dbg_client_sysrepo, "sysrepo: providing RPC to '%s'",
 	       nb_node->xpath);