doc.silverstripe.org/sapphire/security/Authenticator.php

<?php
/**
 * Abstract base class for an authentication method
 *
 * This class is used as a base class for the different authentication
 * methods like {@link MemberAuthenticator} or {@link OpenIDAuthenticator}.
 *
 * @author Markus Lanthaler <markus@silverstripe.com>
 * @package sapphire
 * @subpackage security
 */
abstract class Authenticator extends Object {

  /**
   * This variable holds all authenticators that should be used
   *
   * @var array
   */
  private static $authenticators = array('MemberAuthenticator');
  
  /**
   * Used to influence the order of authenticators on the login-screen
   * (default shows first).
   * 
   * @var string
   */
  private static $default_authenticator = 'MemberAuthenticator';


  /**
   * Method to authenticate an user
   *
   * @param array $RAW_data Raw data to authenticate the user
   * @param Form $form Optional: If passed, better error messages can be
   *                             produced by using
   *                             {@link Form::sessionMessage()}
   * @return bool|Member Returns FALSE if authentication fails, otherwise
   *                     the member object
   */
  public abstract static function authenticate($RAW_data,
                                               Form $form = null);


  /**
   * Method that creates the login form for this authentication method
   *
   * @param Controller The parent controller, necessary to create the
   *                   appropriate form action tag
   * @return Form Returns the login form to use with this authentication
   *              method
   */
  public abstract static function get_login_form(Controller $controller);


  /**
   * Get the name of the authentication method
   *
   * @return string Returns the name of the authentication method.
   */
  public abstract static function get_name();

  public static function register($authenticator) {
	self::register_authenticator($authenticator);	
  }


  /**
   * Register a new authenticator
   *
   * The new authenticator has to exist and to be derived from the
   * {@link Authenticator}.
   * Every authenticator can be registered only once.
   *
   * @param string $authenticator Name of the authenticator class to
   *                              register
   * @return bool Returns TRUE on success, FALSE otherwise.
   */
  public static function register_authenticator($authenticator) {
    $authenticator = trim($authenticator);

    if(class_exists($authenticator) == false)
      return false;

    if(is_subclass_of($authenticator, 'Authenticator') == false)
      return false;

    if(in_array($authenticator, self::$authenticators) == false) {
      if(call_user_func(array($authenticator, 'on_register')) === true) {
        array_push(self::$authenticators, $authenticator);
      } else {
        return false;
      }
    }

    return true;
  }
  
  public static function unregister($authenticator) {
  	self::unregister_authenticator($authenticator);
  }
  
	/**
	 * Remove a previously registered authenticator
	 *
	 * @param string $authenticator Name of the authenticator class to register
	 * @return bool Returns TRUE on success, FALSE otherwise.
	 */
	public static function unregister_authenticator($authenticator) {
		if(call_user_func(array($authenticator, 'on_unregister')) === true) {
        	if(in_array($authenticator, self::$authenticators)) {
        		unset(self::$authenticators[array_search($authenticator, self::$authenticators)]);
        	}
		};
	}


  /**
   * Check if a given authenticator is registered
   *
   * @param string $authenticator Name of the authenticator class to check
   * @return bool Returns TRUE if the authenticator is registered, FALSE
   *              otherwise.
   */
  public static function is_registered($authenticator) {
    return in_array($authenticator, self::$authenticators);
  }


  /**
   * Get all registered authenticators
   *
   * @return array Returns an array with the class names of all registered
   *               authenticators.
   */
  public static function get_authenticators() {
    // put default authenticator first (mainly for tab-order on loginform)
    if($key = array_search(self::$default_authenticator,self::$authenticators)) {
    	unset(self::$authenticators[$key]);
	    array_unshift(self::$authenticators, self::$default_authenticator);
    }

    return self::$authenticators;
  }
  
  /**
   * Set a default authenticator (shows first in tabs)
   *
   * @param string
   */
  public static function set_default_authenticator($authenticator) {
    self::$default_authenticator = $authenticator;
    
    
  }
  
  /**
   * @return string
   */
  public static function get_default_authenticator() {
    return self::$default_authenticator;
  }


  /**
   * Callback function that is called when the authenticator is registered
   *
   * Use this method for initialization of a newly registered authenticator.
   * Just overload this method and it will be called when the authenticator
   * is registered.
   * <b>If the method returns FALSE, the authenticator won't be
   * registered!</b>
   *
   * @return bool Returns TRUE on success, FALSE otherwise.
   */
  protected static function on_register() {
    return true;
  }
  
  /**
   * Callback function that is called when an authenticator is removed.
   *
   * @return bool
   */
  protected static function on_unregister() {
    return true;
  }
}

?>