I'm using Netopeer2 library for Netconf client and server. Command line program source codes of client and server are available.
In client side, upon executing get-config for specific yang model, the response is printed in the command line.
However I want to fetch the value of the Leaf node from that response and use it for my application.
The response is received in lyd_node*.
I got the hint online to use lyd_find_path() of libyang to do this. I called it like this:
LY_ERR ret = lyd_find_path(op, "/etsi-qkd-sdn-node:qkd_node/qkdn_version", 1, &match);
Upon debugging lyd_find_path(), I found that it is failing at the line
ret = ly_path_eval_partial(lypath, ctx_node, NULL, 0, NULL, match).
The error value is: LY_ENOTFOUND
The return value of LY_ENOTFOUND is expected, because as the documentation of lyd_find_path() states:
Search in given data for a node uniquely identified by a path. Always works in constant (O(1)) complexity. To be exact, it is O(n) where n is the depth of the path used. Opaque nodes are NEVER found/traversed.
As the ietf-netconf YANG module specifies, the reply to get-config is enveloped in a node called data which is of type anyxml (= opaque).
A possible solution to this is to obtain the tree you are interested in from this data node. An illustration of how this can be achieved:
/* calling lyd_child, because op is the node <get-config>, but we are interested in <data> */
struct lyd_node_any *data = (struct lyd_node_any *)lyd_child(op);
struct lyd_node *tree = data->value.tree;
struct lyd_node *node;
LY_ERR ret = lyd_find_path(tree, "/etsi-qkd-sdn-node:qkd_node/qkdn_version", 0, &node);
if (!ret) {
printf("Value of the node %s is %s\n", LYD_NAME(node), lyd_get_value(node));
}