Hook before login authetification or redirect to login again

[Bundschuh]

Hello,

my purpose is to extend the login process to check another database if a user doesn't yet exists in vb db. If the given username matches on the other database then a new vb user will be created. This works fine using datamanager etc.
The user should then be automatically logged in but that doesn't work. A new user will created but not logged in. Instead he will be redirected to login page again.

I tried hook location "login_failure", but looking in the code I saw that it can't work. The hook is called after function verify_authentication, which will of course return false if a user doesn't exists yet.

Is there a hook I can use which is called before? Maybe I have overseen something.

If not a possible solution would be to redirect to login again using same post data. How can I realize this? Does vB API provide some function for this?

Thanks in advance. I'd really appreciate.
Greetings
Bundschuh
The hook is directly called after user