Getting only active interfaces (collectd-snmp6-plugin)

Hey, I try to run through all interfaces that are currently available. I fist used getifaddrs for collecting all interfaces. Somehow, wireguard interfaces were not included. I switched now to if_nameindex.

However, now I need to know if an interface is down (if it is down it has no snmp6 interface). So actually I need


To get this, I have to use getifaddrs again. This seems somehow stupid. I already thought about using netlink. Can someone point me to the correct solution?