How to count the time a Windows users is logged in (VC++)

Question

I am writing a Windows service for doing Parental Control (Visual C++).

I am having trouble with the following:

• how to count the time a Windows user has been logged on today (time measured in hours)
• how to trigger log-off from the user Windows account, when time per day exceeds a specified value, say 5 hours.

Any help is appreciated.
Regards!

Answer 1

To do that I think there may me several ways.
I think the simplest one is to use a timer that could be launched when the service start (or when your application start if placed in the startup menu).
For that you can use the SetTimer method associated to a WM_TIMER message :
http://msdn.microsoft.com/en-us/library/ms644906(v=vs.85).aspx

You should get the time before the launching of the timer using a CTime function for example :

CTime t;
t.GetCurrentTime ();
timeAtLaunched=t.GetSecond(); //or GetHour()

After that you can put a similar CTime call inside your timer function to have a currentTime value and calculate a difference between the currentTime value and the timeAtLaunched value

To keep the connected time during a day if an user connect and disconnect several times, you should keep the difference value inside a file or inside the registry.

To force logoff, you can use :

ExitWindowsEx (EWX_SHUTDOWN | EWX_FORCE, SHTDN_REASON_MAJOR_OPERATINGSYSTEM |
  SHTDN_REASON_MINOR_UPGRADE | SHTDN_REASON_FLAG_PLANNED)