Implement authentication with LDAP

Enable an additional lookup against an LDAP directory
during login and user creation to ensure that only
specific users can login and register on the EteBase
server instance.

django_etebase/utils.py

@@ -2,6 +2,7 @@ from django.contrib.auth import get_user_model
 from django.core.exceptions import PermissionDenied
 
 from . import app_settings
+from .ldap import LDAPConnection
 
 
 User = get_user_model()
@@ -15,6 +16,11 @@ def get_user_queryset(queryset, view):
 
 
 def create_user(*args, **kwargs):
+    # Check if the LDAP query returns exactly one user
+    if app_settings.USE_LDAP:
+        if not LDAPConnection.get_instance().has_user(kwargs['username']):
+            raise PermissionDenied('User is not listed in the LDAP registry.')
+
     custom_func = app_settings.CREATE_USER_FUNC
     if custom_func is not None:
         return custom_func(*args, **kwargs)