Authentication either username or mac address

[Mohammad Mahefooz]

 I have searched about this, but couldn't find proper answer. If it has
been already answered kindly share the link. Would like to authenticate
users either with username or specified mac address. Generally we can
authenticate users either when using only username or only mac address
(using mac authentication). But let's say we want to give users the option
of either using username or mac address to login, but count data and
session time on username basis, how to achieve this in freeradius?

- Mohammad