Getting logged-on username from a service

Question

I have a service that I had to log on to the local admin to install. The pupose of this service to log when a user is logging in or out to record their username. I finally f

Answer 1

Here's my code (all of them residing inside a class; in my case, the class inheriting ServiceBase).

    [DllImport("Wtsapi32.dll")]
    private static extern bool WTSQuerySessionInformation(IntPtr hServer, int sessionId, WtsInfoClass wtsInfoClass, out IntPtr ppBuffer, out int pBytesReturned);
    [DllImport("Wtsapi32.dll")]
    private static extern void WTSFreeMemory(IntPtr pointer);

    private enum WtsInfoClass
    {
        WTSUserName = 5, 
        WTSDomainName = 7,
    }

    private static string GetUsername(int sessionId, bool prependDomain = true)
    {
        IntPtr buffer;
        int strLen;
        string username = "SYSTEM";
        if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WtsInfoClass.WTSUserName, out buffer, out strLen) && strLen > 1)
        {
            username = Marshal.PtrToStringAnsi(buffer);
            WTSFreeMemory(buffer);
            if (prependDomain)
            {
                if (WTSQuerySessionInformation(IntPtr.Zero, sessionId, WtsInfoClass.WTSDomainName, out buffer, out strLen) && strLen > 1)
                {
                    username = Marshal.PtrToStringAnsi(buffer) + "\\" + username;
                    WTSFreeMemory(buffer);
                }
            }
        }
        return username;
    }

With the above code in your class, you can simply get the username in the method you're overriding like this:

protected override void OnSessionChange(SessionChangeDescription changeDescription)
{
    string username = GetUsername(changeDescription.SessionId);
    //continue with any other thing you wish to do
}