Description

Capabilities of 6Lo-ND to get a device's EUI-64 for the ARO are not portable beyond IEEE 802.15.4 at the moment. The two culprits for that are

Which expects the device to provide NETOPT_ADDRESS_LONG which then is the EUI-64 (which isn't necessarily the case for non-IEEE-802.15.4 devices) and

which expects the configured link-layer address for the interface to be the devices EUI-64 (which isn't necessarily the case even for IEEE 802.15.4 devices).

From the past handlings with device specific data that is not necessarily intrinsic to the device (but might be generated from such data) it became best practice to add the getters for such data to sys/net/gnrc/netif/gnrc_netif_device_type.c. There a e.g. gnrc_netif_get_eui64() could reside. However, most device types already support generating (or getting) getting the EUI-64 with the _get_iid() functionality

So to prevent further code duplication I'd like to attack this smart. For the most part (EUI-48 to IPv6 IID, Nordic softdevice, "short address devices...) it is easy to just wrap the get_iid function around a get_eui64 function, the latter being the same as the original get_iid function, just without flipping the 0x02 bit. However, device types like IEEE 802.15.4 where the EUI-64 is an actual address existing on the device might be problematic.