Retrieving MAC address from struct ifnet

Hello,

I am trying to read MAC address of network interface in kernel from 
member of struct ifnet:

struct ifaddr	*if_hwdl;

When I try to cycle through interfaces and I read first member of 
if_hwdl (struct	sockaddr *ifa_addr) the result for ethernet is:

sa_family: 18, sa_len: 17,
sa_data: 01 00 06 03 06 00 77 6D 30 F0 DE F1 8F AD EB 00 00

and the result for wireless is:

sa_family: 18, sa_len: 18,
sa_data: 02 00 06 04 06 00 69 77 6E 30 08 11 96 52 DA 90 00 00

where
F0 DE F1 8F AD EB
and
08 11 96 52 DA 90

are MAC addresses of my network cards.

How can I reliably retrieve index of first byte of these MAC addresses ?
Or does exist easier way how to retrieve MAC address from struct ifnet ?

Peter