0

Hello forum,

I am not skilled in php. A novice.

I have a Joomla site and the front page is blank.

After inserting a code given to me to reveal the error for the white screen.

This error message is now showing. I have no idea how to correct this and really would love some help. Tiffany.

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/content/33/8710233/html/index.php:5) in /home/content/33/8710233/html/libraries/joomla/session/session.php on line 492

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5 Years
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Last Post by tiffster
0

It means session_start() is called in your code AFTER html or whitespace has been outputted. Most often, people have some whitespace before their <?php

0

Hello forum,

Thank you for your reply. I can see on line 492 that there are no problems. My entire website is not visible, just a white page.

http://pawlets.com

This is the session php. I have been up all night trying to solve this.

<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Session
 *
 * @copyright   Copyright (C) 2005 - 2012 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

// Register the session storage class with the loader
JLoader::register('JSessionStorage', dirname(__FILE__) . '/storage.php');

jimport('joomla.environment.request');

/**
 * Class for managing HTTP sessions
 *
 * Provides access to session-state values as well as session-level
 * settings and lifetime management methods.
 * Based on the standard PHP session handling mechanism it provides
 * more advanced features such as expire timeouts.
 *
 * @package     Joomla.Platform
 * @subpackage  Session
 * @since       11.1
 */
class JSession extends JObject
{

    /**
     * Internal state.
     * One of 'active'|'expired'|'destroyed|'error'
     *
     * @var    string
     * @see    getState()
     * @since  11.1
     */
    protected $_state = 'active';

    /**
     * Maximum age of unused session in minutes
     *
     * @var    string
     * @since  11.1
     */
    protected $_expire = 15;

    /**
     * The session store object.
     *
     * @var    JSessionStorage
     * @since  11.1
     */
    protected $_store = null;

    /**
     * Security policy.
     * List of checks that will be done.
     *
     * Default values:
     * - fix_browser
     * - fix_adress
     *
     * @var array
     * @since  11.1
     */
    protected $_security = array('fix_browser');

    /**
     * Force cookies to be SSL only
     * Default  false
     *
     * @var    boolean
     * @since  11.1
     */
    protected $_force_ssl = false;

    /**
     * @var    JSession  JSession instances container.
     * @since  11.3
     */
    protected static $instance;

    /**
     * Constructor
     *
     * @param   string  $store    The type of storage for the session.
     * @param   array   $options  Optional parameters
     *
     * @since   11.1
     */
    public function __construct($store = 'none', $options = array())
    {
        // Need to destroy any existing sessions started with session.auto_start
        if (session_id())
        {
            session_unset();
            session_destroy();
        }

        // set default sessios save handler
        ini_set('session.save_handler', 'files');

        // disable transparent sid support
        ini_set('session.use_trans_sid', '0');

        // create handler
        $this->_store = JSessionStorage::getInstance($store, $options);

        // set options
        $this->_setOptions($options);

        $this->_setCookieParams();

        // load the session
        $this->_start();

        // initialise the session
        $this->_setCounter();
        $this->_setTimers();

        $this->_state = 'active';

        // perform security checks
        $this->_validate();
    }

    /**
     * Session object destructor
     *
     * @since   11.1
     */
    public function __destruct()
    {
        $this->close();
    }

    /**
     * Returns the global Session object, only creating it
     * if it doesn't already exist.
     *
     * @param   string  $handler  The type of session handler.
     * @param   array   $options  An array of configuration options.
     *
     * @return  JSession  The Session object.
     *
     * @since   11.1
     */
    public static function getInstance($handler, $options)
    {
        if (!is_object(self::$instance))
        {
            self::$instance = new JSession($handler, $options);
        }

        return self::$instance;
    }

    /**
     * Get current state of session
     *
     * @return  string  The session state
     *
     * @since   11.1
     */
    public function getState()
    {
        return $this->_state;
    }

    /**
     * Get expiration time in minutes
     *
     * @return  integer  The session expiration time in minutes
     *
     * @since   11.1
     */
    public function getExpire()
    {
        return $this->_expire;
    }

    /**
     * Get a session token, if a token isn't set yet one will be generated.
     *
     * Tokens are used to secure forms from spamming attacks. Once a token
     * has been generated the system will check the post request to see if
     * it is present, if not it will invalidate the session.
     *
     * @param   boolean  $forceNew  If true, force a new token to be created
     *
     * @return  string  The session token
     *
     * @since   11.1
     */
    public function getToken($forceNew = false)
    {
        $token = $this->get('session.token');

        //create a token
        if ($token === null || $forceNew)
        {
            $token = $this->_createToken(12);
            $this->set('session.token', $token);
        }

        return $token;
    }

    /**
     * Method to determine if a token exists in the session. If not the
     * session will be set to expired
     *
     * @param   string   $tCheck       Hashed token to be verified
     * @param   boolean  $forceExpire  If true, expires the session
     *
     * @return  boolean
     *
     * @since   11.1
     */
    public function hasToken($tCheck, $forceExpire = true)
    {
        // check if a token exists in the session
        $tStored = $this->get('session.token');

        //check token
        if (($tStored !== $tCheck))
        {
            if ($forceExpire)
            {
                $this->_state = 'expired';
            }
            return false;
        }

        return true;
    }

    /**
     * Method to determine a hash for anti-spoofing variable names
     *
     * @param   boolean  $forceNew  If true, force a new token to be created
     *
     * @return  string  Hashed var name
     *
     * @since   11.1
     */
    public static function getFormToken($forceNew = false)
    {
        $user = JFactory::getUser();
        $session = JFactory::getSession();
        $hash = JApplication::getHash($user->get('id', 0) . $session->getToken($forceNew));

        return $hash;
    }

    /**
     * Get session name
     *
     * @return  string  The session name
     *
     * @since   11.1
     */
    public function getName()
    {
        if ($this->_state === 'destroyed')
        {
            // @TODO : raise error
            return null;
        }
        return session_name();
    }

    /**
     * Get session id
     *
     * @return  string  The session name
     *
     * @since   11.1
     */
    public function getId()
    {
        if ($this->_state === 'destroyed')
        {
            // @TODO : raise error
            return null;
        }
        return session_id();
    }

    /**
     * Get the session handlers
     *
     * @return  array  An array of available session handlers
     *
     * @since   11.1
     */
    public static function getStores()
    {
        jimport('joomla.filesystem.folder');
        $handlers = JFolder::files(dirname(__FILE__) . '/storage', '.php$');

        $names = array();
        foreach ($handlers as $handler)
        {
            $name = substr($handler, 0, strrpos($handler, '.'));
            $class = 'JSessionStorage' . ucfirst($name);

            //Load the class only if needed
            if (!class_exists($class))
            {
                require_once dirname(__FILE__) . '/storage/' . $name . '.php';
            }

            if (call_user_func_array(array(trim($class), 'test'), array()))
            {
                $names[] = $name;
            }
        }

        return $names;
    }

    /**
     * Check whether this session is currently created
     *
     * @return  boolean  True on success.
     *
     * @since   11.1
     */
    public function isNew()
    {
        $counter = $this->get('session.counter');
        if ($counter === 1)
        {
            return true;
        }
        return false;
    }

    /**
     * Get data from the session store
     *
     * @param   string  $name       Name of a variable
     * @param   mixed   $default    Default value of a variable if not set
     * @param   string  $namespace  Namespace to use, default to 'default'
     *
     * @return  mixed  Value of a variable
     *
     * @since   11.1
     */
    public function get($name, $default = null, $namespace = 'default')
    {
        $namespace = '__' . $namespace; //add prefix to namespace to avoid collisions

        if ($this->_state !== 'active' && $this->_state !== 'expired')
        {
            // @TODO :: generated error here
            $error = null;
            return $error;
        }

        if (isset($_SESSION[$namespace][$name]))
        {
            return $_SESSION[$namespace][$name];
        }
        return $default;
    }

    /**
     * Set data into the session store.
     *
     * @param   string  $name       Name of a variable.
     * @param   mixed   $value      Value of a variable.
     * @param   string  $namespace  Namespace to use, default to 'default'.
     *
     * @return  mixed  Old value of a variable.
     *
     * @since   11.1
     */
    public function set($name, $value = null, $namespace = 'default')
    {
        $namespace = '__' . $namespace; //add prefix to namespace to avoid collisions

        if ($this->_state !== 'active')
        {
            // @TODO :: generated error here
            return null;
        }

        $old = isset($_SESSION[$namespace][$name]) ? $_SESSION[$namespace][$name] : null;

        if (null === $value)
        {
            unset($_SESSION[$namespace][$name]);
        }
        else
        {
            $_SESSION[$namespace][$name] = $value;
        }

        return $old;
    }

    /**
     * Check whether data exists in the session store
     *
     * @param   string  $name       Name of variable
     * @param   string  $namespace  Namespace to use, default to 'default'
     *
     * @return  boolean  True if the variable exists
     *
     * @since   11.1
     */
    public function has($name, $namespace = 'default')
    {
        // Add prefix to namespace to avoid collisions.
        $namespace = '__' . $namespace;

        if ($this->_state !== 'active')
        {
            // @TODO :: generated error here
            return null;
        }

        return isset($_SESSION[$namespace][$name]);
    }

    /**
     * Unset data from the session store
     *
     * @param   string  $name       Name of variable
     * @param   string  $namespace  Namespace to use, default to 'default'
     *
     * @return  mixed   The value from session or NULL if not set
     *
     * @since   11.1
     */
    public function clear($name, $namespace = 'default')
    {
        // Add prefix to namespace to avoid collisions
        $namespace = '__' . $namespace;

        if ($this->_state !== 'active')
        {
            // @TODO :: generated error here
            return null;
        }

        $value = null;
        if (isset($_SESSION[$namespace][$name]))
        {
            $value = $_SESSION[$namespace][$name];
            unset($_SESSION[$namespace][$name]);
        }

        return $value;
    }

    /**
     * Start a session.
     *
     * Creates a session (or resumes the current one based on the state of the session)
     *
     * @return  boolean  true on success
     *
     * @since   11.1
     */
    protected function _start()
    {
        // Start session if not started
        if ($this->_state == 'restart')
        {
            session_id($this->_createId());
        }
        else
        {
            $session_name = session_name();
            if (!JRequest::getVar($session_name, false, 'COOKIE'))
            {
                if (JRequest::getVar($session_name))
                {
                    session_id(JRequest::getVar($session_name));
                    setcookie($session_name, '', time() - 3600);
                }
            }
        }

        session_cache_limiter('none');
        session_start();

        return true;
    }

    /**
     * Frees all session variables and destroys all data registered to a session
     *
     * This method resets the $_SESSION variable and destroys all of the data associated
     * with the current session in its storage (file or DB). It forces new session to be
     * started after this method is called. It does not unset the session cookie.
     *
     * @return  boolean  True on success
     *
     * @see     session_destroy()
     * @see     session_unset()
     * @since   11.1
     */
    public function destroy()
    {
        // Session was already destroyed
        if ($this->_state === 'destroyed')
        {
            return true;
        }

        // In order to kill the session altogether, such as to log the user out, the session id
        // must also be unset. If a cookie is used to propagate the session id (default behavior),
        // then the session cookie must be deleted.
        if (isset($_COOKIE[session_name()]))
        {
            $config = JFactory::getConfig();
            $cookie_domain = $config->get('cookie_domain', '');
            $cookie_path = $config->get('cookie_path', '/');
            setcookie(session_name(), '', time() - 42000, $cookie_path, $cookie_domain);
        }

        session_unset();
        session_destroy();

        $this->_state = 'destroyed';
        return true;
    }

    /**
     * Restart an expired or locked session.
     *
     * @return  boolean  True on success
     *
     * @see     destroy
     * @since   11.1
     */
    public function restart()
    {
        $this->destroy();
        if ($this->_state !== 'destroyed')
        {
            // @TODO :: generated error here
            return false;
        }

        // Re-register the session handler after a session has been destroyed, to avoid PHP bug
        $this->_store->register();

        $this->_state = 'restart';
        //regenerate session id
        $id = $this->_createId();
        session_id($id);
        $this->_start();
        $this->_state = 'active';

        $this->_validate();
        $this->_setCounter();

        return true;
    }

    /**
     * Create a new session and copy variables from the old one
     *
     * @return  boolean $result true on success
     *
     * @since   11.1
     */
    public function fork()
    {
        if ($this->_state !== 'active')
        {
            // @TODO :: generated error here
            return false;
        }

        // Save values
        $values = $_SESSION;

        // Keep session config
        $trans = ini_get('session.use_trans_sid');
        if ($trans)
        {
            ini_set('session.use_trans_sid', 0);
        }
        $cookie = session_get_cookie_params();

        // Create new session id
        $id = $this->_createId();

        // Kill session
        session_destroy();

        // Re-register the session store after a session has been destroyed, to avoid PHP bug
        $this->_store->register();

        // restore config
        ini_set('session.use_trans_sid', $trans);
        session_set_cookie_params($cookie['lifetime'], $cookie['path'], $cookie['domain'], $cookie['secure']);

        // restart session with new id
        session_id($id);
        session_start();

        return true;
    }

    /**
     * Writes session data and ends session
     *
     * Session data is usually stored after your script terminated without the need
     * to call JSession::close(), but as session data is locked to prevent concurrent
     * writes only one script may operate on a session at any time. When using
     * framesets together with sessions you will experience the frames loading one
     * by one due to this locking. You can reduce the time needed to load all the
     * frames by ending the session as soon as all changes to session variables are
     * done.
     *
     * @return  void
     *
     * @see     session_write_close()
     * @since   11.1
     */
    public function close()
    {
        session_write_close();
    }

    /**
     * Create a session id
     *
     * @return  string  Session ID
     *
     * @since   11.1
     */
    protected function _createId()
    {
        $id = 0;
        while (strlen($id) < 32)
        {
            $id .= mt_rand(0, mt_getrandmax());
        }

        $id = md5(uniqid($id, true));
        return $id;
    }

    /**
     * Set session cookie parameters
     *
     * @return  void
     *
     * @since   11.1
     */
    protected function _setCookieParams()
    {
        $cookie = session_get_cookie_params();
        if ($this->_force_ssl)
        {
            $cookie['secure'] = true;
        }

        $config = JFactory::getConfig();

        if ($config->get('cookie_domain', '') != '')
        {
            $cookie['domain'] = $config->get('cookie_domain');
        }

        if ($config->get('cookie_path', '') != '')
        {
            $cookie['path'] = $config->get('cookie_path');
        }
        session_set_cookie_params($cookie['lifetime'], $cookie['path'], $cookie['domain'], $cookie['secure']);
    }

    /**
     * Create a token-string
     *
     * @param   integer  $length  Length of string
     *
     * @return  string  Generated token
     *
     * @since   11.1
     */
    protected function _createToken($length = 32)
    {
        static $chars = '0123456789abcdef';
        $max = strlen($chars) - 1;
        $token = '';
        $name = session_name();
        for ($i = 0; $i < $length; ++$i)
        {
            $token .= $chars[(rand(0, $max))];
        }

        return md5($token . $name);
    }

    /**
     * Set counter of session usage
     *
     * @return  boolean  True on success
     *
     * @since   11.1
     */
    protected function _setCounter()
    {
        $counter = $this->get('session.counter', 0);
        ++$counter;

        $this->set('session.counter', $counter);
        return true;
    }

    /**
     * Set the session timers
     *
     * @return  boolean  True on success
     *
     * @since   11.1
     */
    protected function _setTimers()
    {
        if (!$this->has('session.timer.start'))
        {
            $start = time();

            $this->set('session.timer.start', $start);
            $this->set('session.timer.last', $start);
            $this->set('session.timer.now', $start);
        }

        $this->set('session.timer.last', $this->get('session.timer.now'));
        $this->set('session.timer.now', time());

        return true;
    }

    /**
     * Set additional session options
     *
     * @param   array  &$options  List of parameter
     *
     * @return  boolean  True on success
     *
     * @since   11.1
     */
    protected function _setOptions(&$options)
    {
        // Set name
        if (isset($options['name']))
        {
            session_name(md5($options['name']));
        }

        // Set id
        if (isset($options['id']))
        {
            session_id($options['id']);
        }

        // Set expire time
        if (isset($options['expire']))
        {
            $this->_expire = $options['expire'];
        }

        // Get security options
        if (isset($options['security']))
        {
            $this->_security = explode(',', $options['security']);
        }

        if (isset($options['force_ssl']))
        {
            $this->_force_ssl = (bool) $options['force_ssl'];
        }

        // Sync the session maxlifetime
        ini_set('session.gc_maxlifetime', $this->_expire);

        return true;
    }

    /**
     * Do some checks for security reason
     *
     * - timeout check (expire)
     * - ip-fixiation
     * - browser-fixiation
     *
     * If one check failed, session data has to be cleaned.
     *
     * @param   boolean  $restart  Reactivate session
     *
     * @return  boolean  True on success
     *
     * @see     http://shiflett.org/articles/the-truth-about-sessions
     * @since   11.1
     */
    protected function _validate($restart = false)
    {
        // Allow to restart a session
        if ($restart)
        {
            $this->_state = 'active';

            $this->set('session.client.address', null);
            $this->set('session.client.forwarded', null);
            $this->set('session.client.browser', null);
            $this->set('session.token', null);
        }

        // Check if session has expired
        if ($this->_expire)
        {
            $curTime = $this->get('session.timer.now', 0);
            $maxTime = $this->get('session.timer.last', 0) + $this->_expire;

            // Empty session variables
            if ($maxTime < $curTime)
            {
                $this->_state = 'expired';
                return false;
            }
        }

        // Record proxy forwarded for in the session in case we need it later
        if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
        {
            $this->set('session.client.forwarded', $_SERVER['HTTP_X_FORWARDED_FOR']);
        }

        // Check for client address
        if (in_array('fix_adress', $this->_security) && isset($_SERVER['REMOTE_ADDR']))
        {
            $ip = $this->get('session.client.address');

            if ($ip === null)
            {
                $this->set('session.client.address', $_SERVER['REMOTE_ADDR']);
            }
            elseif ($_SERVER['REMOTE_ADDR'] !== $ip)
            {
                $this->_state = 'error';
                return false;
            }
        }

        // Check for clients browser
        if (in_array('fix_browser', $this->_security) && isset($_SERVER['HTTP_USER_AGENT']))
        {
            $browser = $this->get('session.client.browser');

            if ($browser === null)
            {
                $this->set('session.client.browser', $_SERVER['HTTP_USER_AGENT']);
            }
            elseif ($_SERVER['HTTP_USER_AGENT'] !== $browser)
            {
                //              $this->_state   =   'error';
                //              return false;
            }
        }

        return true;
    }
}

Edited by pyTony: fixed formatting

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