silverstripe-framework/security/Security.php
Ingo Schommer 634c91c6ff Merge remote-tracking branch 'origin/3.0' into 3.1
Conflicts:
	email/Mailer.php
2013-01-30 12:46:24 +01:00

964 lines
28 KiB
PHP

<?php
/**
* Implements a basic security model
* @package framework
* @subpackage security
*/
class Security extends Controller {
static $allowed_actions = array(
'index',
'login',
'logout',
'basicauthlogin',
'lostpassword',
'passwordsent',
'changepassword',
'ping',
'LoginForm',
'ChangePasswordForm',
'LostPasswordForm',
);
/**
* Default user name. Only used in dev-mode by {@link setDefaultAdmin()}
*
* @var string
* @see setDefaultAdmin()
*/
protected static $default_username;
/**
* Default password. Only used in dev-mode by {@link setDefaultAdmin()}
*
* @var string
* @see setDefaultAdmin()
*/
protected static $default_password;
/**
* If set to TRUE to prevent sharing of the session across several sites
* in the domain.
*
* @var bool
*/
protected static $strictPathChecking = false;
/**
* The password encryption algorithm to use by default.
* This is an arbitrary code registered through {@link PasswordEncryptor}.
*
* @var string
*/
protected static $encryptionAlgorithm = 'blowfish';
/**
* Showing "Remember me"-checkbox
* on loginform, and saving encrypted credentials to a cookie.
*
* @var bool
*/
public static $autologin_enabled = true;
/**
* Location of word list to use for generating passwords
*
* @var string
*/
protected static $wordlist = './wordlist.txt';
static $template = 'BlankPage';
/**
* Template thats used to render the pages.
*
* @var string
*/
public static $template_main = 'Page';
/**
* Default message set used in permission failures.
*
* @var array|string
*/
protected static $default_message_set = '';
/**
* Random secure token, can be used as a crypto key internally.
* Generate one through 'sake dev/generatesecuretoken'.
*
* @var String
*/
public static $token;
/**
* Get location of word list file
*/
public static function get_word_list() {
return Security::$wordlist;
}
/**
* Enable or disable recording of login attempts
* through the {@link LoginRecord} object.
*
* @var boolean $login_recording
*/
protected static $login_recording = false;
/**
* @var boolean If set to TRUE or FALSE, {@link database_is_ready()}
* will always return FALSE. Used for unit testing.
*/
static $force_database_is_ready = null;
/**
* When the database has once been verified as ready, it will not do the
* checks again.
*
* @var bool
*/
static $database_is_ready = false;
/**
* Set location of word list file
*
* @param string $wordListFile Location of word list file
*/
public static function set_word_list($wordListFile) {
Security::$wordlist = $wordListFile;
}
/**
* Set the default message set used in permissions failures.
*
* @param string|array $messageSet
*/
public static function set_default_message_set($messageSet) {
self::$default_message_set = $messageSet;
}
/**
* Register that we've had a permission failure trying to view the given page
*
* This will redirect to a login page.
* If you don't provide a messageSet, a default will be used.
*
* @param Controller $controller The controller that you were on to cause the permission
* failure.
* @param string|array $messageSet The message to show to the user. This
* can be a string, or a map of different
* messages for different contexts.
* If you pass an array, you can use the
* following keys:
* - default: The default message
* - logInAgain: The message to show
* if the user has just
* logged out and the
* - alreadyLoggedIn: The message to
* show if the user
* is already logged
* in and lacks the
* permission to
* access the item.
*
* The alreadyLoggedIn value can contain a '%s' placeholder that will be replaced with a link
* to log in.
*/
public static function permissionFailure($controller = null, $messageSet = null) {
self::set_ignore_disallowed_actions(true);
if(!$controller) $controller = Controller::curr();
if(Director::is_ajax()) {
$response = ($controller) ? $controller->getResponse() : new SS_HTTPResponse();
$response->setStatusCode(403);
if(!Member::currentUser()) $response->setBody('NOTLOGGEDIN:');
return $response;
} else {
// Prepare the messageSet provided
if(!$messageSet) {
if(self::$default_message_set) {
$messageSet = self::$default_message_set;
} else {
$messageSet = array(
'default' => _t(
'Security.NOTEPAGESECURED',
"That page is secured. Enter your credentials below and we will send "
. "you right along."
),
'alreadyLoggedIn' => _t(
'Security.ALREADYLOGGEDIN',
"You don't have access to this page. If you have another account that "
. "can access that page, you can log in again below.",
"%s will be replaced with a link to log in."
),
'logInAgain' => _t(
'Security.LOGGEDOUT',
"You have been logged out. If you would like to log in again, enter "
. "your credentials below."
)
);
}
}
if(!is_array($messageSet)) {
$messageSet = array('default' => $messageSet);
}
// Work out the right message to show
if(Member::currentUser()) {
$response = ($controller) ? $controller->getResponse() : new SS_HTTPResponse();
$response->setStatusCode(403);
//If 'alreadyLoggedIn' is not specified in the array, then use the default
//which should have been specified in the lines above
if(isset($messageSet['alreadyLoggedIn']))
$message=$messageSet['alreadyLoggedIn'];
else
$message=$messageSet['default'];
// Somewhat hackish way to render a login form with an error message.
$me = new Security();
$form = $me->LoginForm();
$form->sessionMessage($message, 'warning');
Session::set('MemberLoginForm.force_message',1);
$formText = $me->login();
$response->setBody($formText);
return $response;
} else {
$message = $messageSet['default'];
}
Session::set("Security.Message.message", $message);
Session::set("Security.Message.type", 'warning');
Session::set("BackURL", $_SERVER['REQUEST_URI']);
// TODO AccessLogEntry needs an extension to handle permission denied errors
// Audit logging hook
$controller->extend('permissionDenied', $member);
$controller->redirect(
Config::inst()->get('Security', 'login_url')
. "?BackURL=" . urlencode($_SERVER['REQUEST_URI'])
);
}
return;
}
/**
* Get the login form to process according to the submitted data
*/
public function LoginForm() {
if(isset($this->requestParams['AuthenticationMethod'])) {
$authenticator = trim($_REQUEST['AuthenticationMethod']);
$authenticators = Authenticator::get_authenticators();
if(in_array($authenticator, $authenticators)) {
return call_user_func(array($authenticator, 'get_login_form'), $this);
}
}
else {
if($authenticator = Authenticator::get_default_authenticator()) {
return call_user_func(array($authenticator, 'get_login_form'), $this);
}
}
user_error('Passed invalid authentication method', E_USER_ERROR);
}
/**
* Get the login forms for all available authentication methods
*
* @return array Returns an array of available login forms (array of Form
* objects).
*
* @todo Check how to activate/deactivate authentication methods
*/
public function GetLoginForms()
{
$forms = array();
$authenticators = Authenticator::get_authenticators();
foreach($authenticators as $authenticator) {
array_push($forms,
call_user_func(array($authenticator, 'get_login_form'),
$this));
}
return $forms;
}
/**
* Get a link to a security action
*
* @param string $action Name of the action
* @return string Returns the link to the given action
*/
public function Link($action = null) {
return "Security/$action";
}
/**
* This action is available as a keep alive, so user
* sessions don't timeout. A common use is in the admin.
*/
public function ping() {
return 1;
}
/**
* Log the currently logged in user out
*
* @param bool $redirect Redirect the user back to where they came.
* - If it's false, the code calling logout() is
* responsible for sending the user where-ever
* they should go.
*/
public function logout($redirect = true) {
$member = Member::currentUser();
if($member) $member->logOut();
if($redirect) $this->redirectBack();
}
/**
* Show the "login" page
*
* @return string Returns the "login" page as HTML code.
*/
public function login() {
// Event handler for pre-login, with an option to let it break you out of the login form
$eventResults = $this->extend('onBeforeSecurityLogin');
// If there was a redirection, return
if($this->redirectedTo()) return;
// If there was an SS_HTTPResponse object returned, then return that
else if($eventResults) {
foreach($eventResults as $result) {
if($result instanceof SS_HTTPResponse) return $result;
}
}
$customCSS = project() . '/css/tabs.css';
if(Director::fileExists($customCSS)) {
Requirements::css($customCSS);
}
if(class_exists('SiteTree')) {
$tmpPage = new Page();
$tmpPage->Title = _t('Security.LOGIN', 'Log in');
$tmpPage->URLSegment = "Security";
// Disable ID-based caching of the log-in page by making it a random number
$tmpPage->ID = -1 * rand(1,10000000);
$controller = Page_Controller::create($tmpPage);
$controller->setDataModel($this->model);
$controller->init();
} else {
$controller = $this;
}
// if the controller calls Director::redirect(), this will break early
if(($response = $controller->getResponse()) && $response->isFinished()) return $response;
$content = '';
$forms = $this->GetLoginForms();
if(!count($forms)) {
user_error('No login-forms found, please use Authenticator::register_authenticator() to add one',
E_USER_ERROR);
}
// only display tabs when more than one authenticator is provided
// to save bandwidth and reduce the amount of custom styling needed
if(count($forms) > 1) {
// Needed because the <base href=".."> in the template makes problems
// with the tabstrip library otherwise
$link_base = Director::absoluteURL($this->Link("login"));
Requirements::javascript(FRAMEWORK_DIR . '/thirdparty/jquery/jquery.js');
Requirements::javascript(FRAMEWORK_DIR . '/thirdparty/jquery-ui/jquery-ui.js');
Requirements::javascript(FRAMEWORK_DIR . '/thirdparty/jquery-entwine/dist/jquery.entwine-dist.js');
Requirements::css(THIRDPARTY_DIR . '/jquery-ui-themes/smoothness/jquery-ui.css');
Requirements::css(FRAMEWORK_DIR . '/css/Security_login.css');
Requirements::javascript(FRAMEWORK_DIR . '/javascript/TabSet.js');
$content = '<div id="Form_EditForm">';
$content .= '<div class="ss-tabset">';
$content .= '<ul>';
$content_forms = '';
foreach($forms as $form) {
$content .= "<li><a href=\"#{$form->FormName()}_tab\">"
. $form->getAuthenticator()->get_name()
. "</a></li>\n";
$content_forms .= '<div class="tab" id="' . $form->FormName() . '_tab">'
. $form->forTemplate() . "</div>\n";
}
$content .= "</ul>\n" . $content_forms . "\n</div>\n</div>\n";
} else {
$content .= $forms[0]->forTemplate();
}
if(strlen($message = Session::get('Security.Message.message')) > 0) {
$message_type = Session::get('Security.Message.type');
if($message_type == 'bad') {
$message = "<p class=\"message $message_type\">$message</p>";
} else {
$message = "<p>$message</p>";
}
$customisedController = $controller->customise(array(
"Content" => $message,
"Form" => $content,
));
} else {
$customisedController = $controller->customise(array(
"Form" => $content,
));
}
Session::clear('Security.Message');
// custom processing
return $customisedController->renderWith(
array('Security_login', 'Security', $this->stat('template_main'), 'BlankPage')
);
}
public function basicauthlogin() {
$member = BasicAuth::requireLogin("SilverStripe login", 'ADMIN');
$member->LogIn();
}
/**
* Show the "lost password" page
*
* @return string Returns the "lost password" page as HTML code.
*/
public function lostpassword() {
if(class_exists('SiteTree')) {
$tmpPage = new Page();
$tmpPage->Title = _t('Security.LOSTPASSWORDHEADER', 'Lost Password');
$tmpPage->URLSegment = 'Security';
$tmpPage->ID = -1; // Set the page ID to -1 so we dont get the top level pages as its children
$controller = Page_Controller::create($tmpPage);
$controller->init();
} else {
$controller = $this;
}
// if the controller calls Director::redirect(), this will break early
if(($response = $controller->getResponse()) && $response->isFinished()) return $response;
$customisedController = $controller->customise(array(
'Content' =>
'<p>' .
_t(
'Security.NOTERESETPASSWORD',
'Enter your e-mail address and we will send you a link with which you can reset your password'
) .
'</p>',
'Form' => $this->LostPasswordForm(),
));
//Controller::$currentController = $controller;
return $customisedController->renderWith(
array('Security_lostpassword', 'Security', $this->stat('template_main'), 'BlankPage')
);
}
/**
* Factory method for the lost password form
*
* @return Form Returns the lost password form
*/
public function LostPasswordForm() {
return MemberLoginForm::create( $this,
'LostPasswordForm',
new FieldList(
new EmailField('Email', _t('Member.EMAIL', 'Email'))
),
new FieldList(
new FormAction(
'forgotPassword',
_t('Security.BUTTONSEND', 'Send me the password reset link')
)
),
false
);
}
/**
* Show the "password sent" page, after a user has requested
* to reset their password.
*
* @param SS_HTTPRequest $request The SS_HTTPRequest for this action.
* @return string Returns the "password sent" page as HTML code.
*/
public function passwordsent($request) {
if(class_exists('SiteTree')) {
$tmpPage = new Page();
$tmpPage->Title = _t('Security.LOSTPASSWORDHEADER');
$tmpPage->URLSegment = 'Security';
$tmpPage->ID = -1; // Set the page ID to -1 so we dont get the top level pages as its children
$controller = Page_Controller::create($tmpPage);
$controller->init();
} else {
$controller = $this;
}
// if the controller calls Director::redirect(), this will break early
if(($response = $controller->getResponse()) && $response->isFinished()) return $response;
$email = Convert::raw2xml(rawurldecode($request->param('ID')) . '.' . $request->getExtension());
$customisedController = $controller->customise(array(
'Title' => _t('Security.PASSWORDSENTHEADER', "Password reset link sent to '{email}'",
array('email' => $email)),
'Content' =>
"<p>"
. _t('Security.PASSWORDSENTTEXT',
"Thank you! A reset link has been sent to '{email}', provided an account exists for this email"
. " address.",
array('email' => $email))
. "</p>",
'Email' => $email
));
//Controller::$currentController = $controller;
return $customisedController->renderWith(
array('Security_passwordsent', 'Security', $this->stat('template_main'), 'BlankPage')
);
}
/**
* Create a link to the password reset form.
*
* GET parameters used:
* - m: member ID
* - t: plaintext token
*
* @param Member $member Member object associated with this link.
* @param string $autoLoginHash The auto login token.
*/
public static function getPasswordResetLink($member, $autologinToken) {
$autologinToken = urldecode($autologinToken);
$selfControllerClass = __CLASS__;
$selfController = new $selfControllerClass();
return $selfController->Link('changepassword') . "?m={$member->ID}&t=$autologinToken";
}
/**
* Show the "change password" page.
* This page can either be called directly by logged-in users
* (in which case they need to provide their old password),
* or through a link emailed through {@link lostpassword()}.
* In this case no old password is required, authentication is ensured
* through the Member.AutoLoginHash property.
*
* @see ChangePasswordForm
*
* @return string Returns the "change password" page as HTML code.
*/
public function changepassword() {
if(class_exists('SiteTree')) {
$tmpPage = new Page();
$tmpPage->Title = _t('Security.CHANGEPASSWORDHEADER', 'Change your password');
$tmpPage->URLSegment = 'Security';
$tmpPage->ID = -1; // Set the page ID to -1 so we dont get the top level pages as its children
$controller = Page_Controller::create($tmpPage);
$controller->init();
} else {
$controller = $this;
}
// if the controller calls Director::redirect(), this will break early
if(($response = $controller->getResponse()) && $response->isFinished()) return $response;
// Extract the member from the URL.
$member = null;
if (isset($_REQUEST['m'])) {
$member = Member::get()->filter('ID', (int)$_REQUEST['m'])->First();
}
// Check whether we are merely changin password, or resetting.
if(isset($_REQUEST['t']) && $member && $member->validateAutoLoginToken($_REQUEST['t'])) {
// On first valid password reset request redirect to the same URL without hash to avoid referrer leakage.
// Store the hash for the change password form. Will be unset after reload within the ChangePasswordForm.
Session::set('AutoLoginHash', $member->encryptWithUserSettings($_REQUEST['t']));
return $this->redirect($this->Link('changepassword'));
} elseif(Session::get('AutoLoginHash')) {
// Subsequent request after the "first load with hash" (see previous if clause).
$customisedController = $controller->customise(array(
'Content' =>
'<p>' .
_t('Security.ENTERNEWPASSWORD', 'Please enter a new password.') .
'</p>',
'Form' => $this->ChangePasswordForm(),
));
} elseif(Member::currentUser()) {
// Logged in user requested a password change form.
$customisedController = $controller->customise(array(
'Content' => '<p>'
. _t('Security.CHANGEPASSWORDBELOW', 'You can change your password below.') . '</p>',
'Form' => $this->ChangePasswordForm()));
} else {
// show an error message if the auto login token is invalid and the
// user is not logged in
if(!isset($_REQUEST['t']) || !$member) {
$customisedController = $controller->customise(
array('Content' =>
_t(
'Security.NOTERESETLINKINVALID',
'<p>The password reset link is invalid or expired.</p>'
. '<p>You can request a new one <a href="{link1}">here</a> or change your password after'
. ' you <a href="{link2}">logged in</a>.</p>',
array('link1' => $this->Link('lostpassword'), 'link2' => $this->link('login'))
)
)
);
} else {
self::permissionFailure(
$this,
_t('Security.ERRORPASSWORDPERMISSION', 'You must be logged in in order to change your password!')
);
return;
}
}
return $customisedController->renderWith(
array('Security_changepassword', 'Security', $this->stat('template_main'), 'BlankPage')
);
}
/**
* Factory method for the lost password form
*
* @return Form Returns the lost password form
*/
public function ChangePasswordForm() {
return new ChangePasswordForm($this, 'ChangePasswordForm');
}
/**
* Return an existing member with administrator privileges, or create one of necessary.
*
* Will create a default 'Administrators' group if no group is found
* with an ADMIN permission. Will create a new 'Admin' member with administrative permissions
* if no existing Member with these permissions is found.
*
* Important: Any newly created administrator accounts will NOT have valid
* login credentials (Email/Password properties), which means they can't be used for login
* purposes outside of any default credentials set through {@link Security::setDefaultAdmin()}.
*
* @return Member
*/
public static function findAnAdministrator() {
// coupling to subsites module
$origSubsite = null;
if(is_callable('Subsite::changeSubsite')) {
$origSubsite = Subsite::currentSubsiteID();
Subsite::changeSubsite(0);
}
$member = null;
// find a group with ADMIN permission
$adminGroup = DataObject::get('Group')
->where("\"Permission\".\"Code\" = 'ADMIN'")
->sort("\"Group\".\"ID\"")
->innerJoin("Permission", "\"Group\".\"ID\"=\"Permission\".\"GroupID\"")
->First();
if(is_callable('Subsite::changeSubsite')) {
Subsite::changeSubsite($origSubsite);
}
if ($adminGroup) {
$member = $adminGroup->Members()->First();
}
if(!$adminGroup) {
singleton('Group')->requireDefaultRecords();
}
if(!$member) {
singleton('Member')->requireDefaultRecords();
$member = Permission::get_members_by_permission('ADMIN')->First();
}
return $member;
}
/**
* Set a default admin in dev-mode
*
* This will set a static default-admin which is not existing
* as a database-record. By this workaround we can test pages in dev-mode
* with a unified login. Submitted login-credentials are first checked
* against this static information in {@link Security::authenticate()}.
*
* @param string $username The user name
* @param string $password The password (in cleartext)
*/
public static function setDefaultAdmin($username, $password) {
// don't overwrite if already set
if(self::$default_username || self::$default_password) {
return false;
}
self::$default_username = $username;
self::$default_password = $password;
}
/**
* Checks if the passed credentials are matching the default-admin.
* Compares cleartext-password set through Security::setDefaultAdmin().
*
* @param string $username
* @param string $password
* @return bool
*/
public static function check_default_admin($username, $password) {
return (
self::$default_username === $username
&& self::$default_password === $password
&& self::has_default_admin()
);
}
/**
* Check that the default admin account has been set.
*/
public static function has_default_admin() {
return !empty(self::$default_username) && !empty(self::$default_password);
}
/**
* Set strict path checking
*
* This prevents sharing of the session across several sites in the
* domain.
*
* @param boolean $strictPathChecking To enable or disable strict patch
* checking.
*/
public static function setStrictPathChecking($strictPathChecking) {
self::$strictPathChecking = $strictPathChecking;
}
/**
* Get strict path checking
*
* @return boolean Status of strict path checking
*/
public static function getStrictPathChecking() {
return self::$strictPathChecking;
}
/**
* Set the password encryption algorithm
*
* @param string $algorithm One of the available password encryption
* algorithms determined by {@link Security::get_encryption_algorithms()}
* @return bool Returns TRUE if the passed algorithm was valid, otherwise FALSE.
*/
public static function set_password_encryption_algorithm($algorithm) {
if(!array_key_exists($algorithm, PasswordEncryptor::get_encryptors())) return false;
self::$encryptionAlgorithm = $algorithm;
return true;
}
/**
* @return String
*/
public static function get_password_encryption_algorithm() {
return self::$encryptionAlgorithm;
}
/**
* Encrypt a password according to the current password encryption settings.
* If the settings are so that passwords shouldn't be encrypted, the
* result is simple the clear text password with an empty salt except when
* a custom algorithm ($algorithm parameter) was passed.
*
* @param string $password The password to encrypt
* @param string $salt Optional: The salt to use. If it is not passed, but
* needed, the method will automatically create a
* random salt that will then be returned as return value.
* @param string $algorithm Optional: Use another algorithm to encrypt the
* password (so that the encryption algorithm can be changed over the time).
* @param Member $member Optional
* @return mixed Returns an associative array containing the encrypted
* password and the used salt in the form:
* <code>
* array(
* 'password' => string,
* 'salt' => string,
* 'algorithm' => string,
* 'encryptor' => PasswordEncryptor instance
* )
* </code>
* If the passed algorithm is invalid, FALSE will be returned.
*
* @see encrypt_passwords()
* @see set_password_encryption_algorithm()
*/
public static function encrypt_password($password, $salt = null, $algorithm = null, $member = null) {
if(
// if the password is empty, don't encrypt
strlen(trim($password)) == 0
// if no algorithm is provided and no default is set, don't encrypt
|| (!$algorithm)
) {
$algorithm = 'none';
} else {
// Fall back to the default encryption algorithm
if(!$algorithm) $algorithm = self::$encryptionAlgorithm;
}
$e = PasswordEncryptor::create_for_algorithm($algorithm);
// New salts will only need to be generated if the password is hashed for the first time
$salt = ($salt) ? $salt : $e->salt($password);
return array(
'password' => $e->encrypt($password, $salt, $member),
'salt' => $salt,
'algorithm' => $algorithm,
'encryptor' => $e
);
}
/**
* Checks the database is in a state to perform security checks.
* See {@link DatabaseAdmin->init()} for more information.
*
* @return bool
*/
public static function database_is_ready() {
// Used for unit tests
if(self::$force_database_is_ready !== NULL) return self::$force_database_is_ready;
if(self::$database_is_ready) return self::$database_is_ready;
$requiredTables = ClassInfo::dataClassesFor('Member');
$requiredTables[] = 'Group';
$requiredTables[] = 'Permission';
foreach($requiredTables as $table) {
// if any of the tables aren't created in the database
if(!ClassInfo::hasTable($table)) return false;
// HACK: DataExtensions aren't applied until a class is instantiated for
// the first time, so create an instance here.
singleton($table);
// if any of the tables don't have all fields mapped as table columns
$dbFields = DB::fieldList($table);
if(!$dbFields) return false;
$objFields = DataObject::database_fields($table);
$missingFields = array_diff_key($objFields, $dbFields);
if($missingFields) return false;
}
self::$database_is_ready = true;
return true;
}
/**
* Enable or disable recording of login attempts
* through the {@link LoginRecord} object.
*
* @param boolean $bool
*/
public static function set_login_recording($bool) {
self::$login_recording = (bool)$bool;
}
/**
* @return boolean
*/
public static function login_recording() {
return self::$login_recording;
}
protected static $default_login_dest = "";
/**
* Set the default login dest
* This is the URL that users will be redirected to after they log in,
* if they haven't logged in en route to access a secured page.
*
* By default, this is set to the homepage
*/
public static function set_default_login_dest($dest) {
self::$default_login_dest = $dest;
}
/**
* Get the default login dest
*/
public static function default_login_dest() {
return self::$default_login_dest;
}
protected static $ignore_disallowed_actions = false;
/**
* Set to true to ignore access to disallowed actions, rather than returning permission failure
* Note that this is just a flag that other code needs to check with Security::ignore_disallowed_actions()
* @param $flag True or false
*/
public static function set_ignore_disallowed_actions($flag) {
self::$ignore_disallowed_actions = $flag;
}
public static function ignore_disallowed_actions() {
return self::$ignore_disallowed_actions;
}
protected static $login_url = "Security/login";
/**
* Set a custom log-in URL if you have built your own log-in page.
*/
public static function set_login_url($loginUrl) {
self::$login_url = $loginUrl;
}
/**
* Get the URL of the log-in page.
* Defaults to Security/login but can be re-set with {@link set_login_url()}
*/
public static function login_url() {
return self::$login_url;
}
}