Windows impersonation for WMI calls via python?

Question

I'm using PyWin32 to make WMI calls to the system in python from my django web application. My goal is to allow users to add printers to the system via a web interface. To do this, I'm using win32print.AddPrinterConnection.

This works well running the development server under my user account. I can add all the printers I want. However, eventually, this will need to run under apache which runs as the LocalSystem account.

This is problematic for two reasons:

1. The LocalSystem account has no network privileges at all, and this is a network printer. The AddPrinterConnection WMI call eventually makes a COM call that will be disallowed.
2. The LocalSystem account has no access to the domain these printers are on. They require a domain account to access.

Therefore, I've come to the conclusion that I need to impersonate domain user(s) to accomplish this task. I've done so using the code found here:

http://code.activestate.com/recipes/81402/

This seems to work as I'm able to verify that I've successfully impersonated the calling code. Unfortunately, after impersonation I always get this error from the win32print.AddPrinterConnection API call:

Exception Type: error 
Exception Value: (2, 'AddPrinterConnection', 'The system cannot find the file specified.')

Do you have any idea why this may be?

Thanks a bunch! Pete

Update

Playing around, I noticed the the AddPrinterConnection API call completes successfully if the user that I'm impersonating is currently logged into the system. Once I log that user out and retry the command while impersonating that user, I get the error stated above.

What is going on here?

Answer 1

I can't help with the specific problem, but I do know that if I had to work with WMI stuff on Windows, with Python, I would definitely reach for Tim Golden's Python WMI module instead of pywin32. Perhaps in the documentation/cookbook or Google searches using that module you can find a solution.