get username from message ?

[frederic heem]

Hi,
Is there a way the get the message sender username ? 
Here is an example:
* A service is running as root
* The message bus is running as messagebus
* An application is running with normal privileges.  
This application connects to the system bus ands sends a message to the 
service. The service shall get information about the message sender, 
especially the username id and group id. Indeed, the service has to write a 
file with the message sender permission.
In the case where an API is missing for that problem, it would be nice to add 
before the 1.0
Thanks,
Frederic Heem