I have a cURL PHP script which is able to validate a username/password against the external source.
What is the best way to integrate this as a login requirement for (select) users in Drupal?Answer1:
To start with, you could look at the code of the OpenID module that comes with Drupal 6 - creating a new module based on this code should get you 90% of the way. It allows existing users to associate OpenIDs with their accounts, and it sounds like you'd need to do something similar from your reply to Henrik.Answer2:
As alternative, you can add a validation function to the form with ID
user_login to verify if the additional conditions are verified. If you do this, remember to add your validation function with
array_unshift(), or the user will be authenticated the same.