Add OneLogin_Saml2_Authn_Request._generate_request_id() override point

Refs #208 (comment)

Author: akx

src/onelogin/saml2/authn_request.py

@@ -47,8 +47,7 @@ def __init__(self, settings, force_authn=False, is_passive=False, set_nameid_pol
         idp_data = self.__settings.get_idp_data()
         security = self.__settings.get_security_data()
 
-        uid = OneLogin_Saml2_Utils.generate_unique_id()
-        self.__id = uid
+        self.__id = self._generate_request_id()
         issue_instant = OneLogin_Saml2_Utils.parse_time_to_SAML(OneLogin_Saml2_Utils.now())
 
         destination = idp_data['singleSignOnService']['url']
@@ -113,7 +112,7 @@ def __init__(self, settings, force_authn=False, is_passive=False, set_nameid_pol
 
         request = OneLogin_Saml2_Templates.AUTHN_REQUEST % \
             {
-                'id': uid,
+                'id': self.__id,
                 'provider_name': provider_name_str,
                 'force_authn_str': force_authn_str,
                 'is_passive_str': is_passive_str,
@@ -129,6 +128,14 @@ def __init__(self, settings, force_authn=False, is_passive=False, set_nameid_pol
 
         self.__authn_request = request
 
+    def _generate_request_id(self):
+        """
+        Generate an unique request ID.
+
+        You can override this in a subclass.
+        """
+        return OneLogin_Saml2_Utils.generate_unique_id()
+
     def get_request(self, deflate=True):
         """
         Returns unsigned AuthnRequest.