domain_client_validate()

[Luke Kenneth Casson Leighton]

the LUID we don't care about at the moment: however we _should_ internally
use it as an index into a shared memory table.  this will inform all smbd
processes that user "xyz" with LUID "NNNN" is "logged in to the domain".

they will then have access rights (as "Domain Users") that can be
distinguished from other rights.  also, the administrator has the option
to kick them off in real time, by forcing the smbd daemon to close their
IPC$ connection to \PIPE\NETLOGON.