How to get AF_SPEC attribute from netlink message using rtnl apis?

There are get apis such as

rtnl_link_get_by_name

I'm reffering to (https://www.infradead.org/~tgr/libnl/doc/api/structrtnl__link.html)

I'm able to get it using following code :

    static void
    netlink_parse_afspec(struct rtattr *rta, int len, int* vlan)
    {
        while (RTA_OK(rta, len)) {
            struct bridge_vlan_info *vinfo;
            switch (rta->rta_type) {
            case IFLA_BRIDGE_VLAN_INFO:
                vinfo = RTA_DATA(rta);
                /*log_debug("netlink", "found VLAN %d on interface %s",
                    vinfo->vid, iff->name ? iff->name : "(unknown)");
    
                bitmap_set(iff->vlan_bmap, vinfo->vid);
                if (vinfo->flags & (BRIDGE_VLAN_INFO_PVID | BRIDGE_VLAN_INFO_UNTAGGED))
                    iff->pvid = vinfo->vid;
                break;*/
                printf("vlan %d \n",vinfo->vid);
            default:
                printf("unknown afspec attribute type %d\n",rta->rta_type);
                break;
            }
            rta = RTA_NEXT(rta, len);
        }
        /* All enbridged interfaces will have VLAN 1 by default, ignore it */
    }
    
int main()
{
//code to receive netlink message
    
     switch(h->nlmsg_type) {
    case IFLA_AF_SPEC:                                                                     netlink_parse_afspec( RTA_DATA(attribute), RTA_PAYLOAD(attribute),vlan);
    }

}