lib, mgmtd: fix processing of yang notifications

Current code assumes that notification is always sent in stripped JSON
format and therefore notification xpath starts at the third symbol of
notification data. Assuming JSON is more or less fine, because this
representation is internal to FRR, but the assumption about the xpath is
wrong, because it won't work for not top-level notifications. YANG
allows to define notification as a child for some data node deep into
the tree and in this case notification data contains not only the
notification node itself, but also all its parents.

To fix the issue, parse the notification data and get its xpath from its
schema node.

Signed-off-by: Igor Ryzhov <iryzhov@nfware.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/lib/yang.c b/lib/yang.c
index adf2ba2ab0..ff7df0b379 100644
--- a/lib/yang.c
+++ b/lib/yang.c
@@ -714,6 +714,52 @@ static void ly_log_cb(LY_LOG_LEVEL level, const char *msg, const char *path)
 		zlog(priority, "libyang: %s", msg);
 }
 
+LY_ERR yang_parse_notification(LYD_FORMAT format, const char *data,
+			       struct lyd_node **notif)
+{
+	struct lyd_node *tree, *dnode;
+	struct ly_in *in = NULL;
+	bool found = false;
+	LY_ERR err;
+
+	err = ly_in_new_memory(data, &in);
+	if (err) {
+		zlog_err("Failed to initialize ly_in: %s", ly_last_errmsg());
+		return err;
+	}
+
+	err = lyd_parse_op(ly_native_ctx, NULL, in, format, LYD_TYPE_NOTIF_YANG,
+			   &tree, NULL);
+	if (err) {
+		zlog_err("Failed to parse notification: %s", ly_last_errmsg());
+		ly_in_free(in, 0);
+		return err;
+	}
+
+	/*
+	 * Notification can be a child of some data node, so traverse the tree
+	 * until we find the notification.
+	 */
+	LYD_TREE_DFS_BEGIN (tree, dnode) {
+		if (dnode->schema->nodetype == LYS_NOTIF) {
+			found = true;
+			break;
+		}
+		LYD_TREE_DFS_END(tree, dnode);
+	}
+
+	if (!found) {
+		zlog_err("Notification not found in the parsed tree");
+		lyd_free_all(tree);
+		ly_in_free(in, 0);
+		return LY_ENOTFOUND;
+	}
+
+	*notif = dnode;
+
+	return LY_SUCCESS;
+}
+
 static ssize_t yang_print_darr(void *arg, const void *buf, size_t count)
 {
 	uint8_t *dst = darr_append_n(*(uint8_t **)arg, count);