Trouble implementing Single Sign On

ArnY

Hello,

I'm working on a CAS Authenticator module. It will be used to share the authentication between different websites in our university.
The principle is simple:
1- the user authenticates himself on the CAS login form
2- he goes to the vanilla forum
3- Authenticator->GetIdentity() checks if there's a current cas session and checks if the user is actually properly authenticated on the CAS system (phpcas::checkauthentication does that)
4- if the user is authenticated on the CAS system then vanilla creates the user on its database if needed, otherwise it loads the data from the data base then create the session using user's data
5- the user is now logged on

BUT point 4 is giving me trouble, indeed, i need to call UserManager->CreateUser() BEFORE the session is started (that's the point) unfortunately CreateUser calls USerManager->AssignRole that actually requires a valid Session (it calls $this->Context->Session->User->Permission)

is there a simple way for me to start a temporary session in order to create create a user object without having to call Authenticate() ?

Thanks