comment with intendation

[phpbb.git] / phpBB / includes / classes / session.php

<?php
/**
*
* @package phpBB3
* @version $Id$
* @copyright (c) 2005, 2008 phpBB Group
* @license http://opensource.org/licenses/gpl-license.php GNU Public License
*
*/

/**
* @ignore
*/
if (!defined('IN_PHPBB'))
{
        exit;
}

/**
* Session class
* @package phpBB3
*/
abstract class phpbb_session
{
        /**
        * @var array Cookie informations
        */
        private $cookie_data = array();

        /**
        * @var array User data
        */
        public $data = array();

        /**
        * @var string Session id
        */
        public $session_id = '';

        /**
        * @var int Current time
        */
        public $time_now = 0;

        /**
        * @var bool True if the current page is updated within the sessions table
        */
        public $update_session_page = true;

        /**
        * @var mixed Reference to authentication system.
        */
        public $auth = NULL;

        /**
        * @var mixed Reference to system array for obtaining server/system information
        */
        public $system = NULL;

        /**
        * @var bool Is true if the user is a logged in registered user
        */
        public $is_registered = false;

        /**
        * @var bool Is true if the user is logged in and a search engine/bot
        */
        public $is_bot = false;

        /**
        * @var array Extra url parameter to append to every URL in phpBB
        */
        public $extra_url = array();

        /**
        * @var bool If this is true then the session id (?sid=[session_id]) is required
        */
        public $need_sid = false;

        /**
        * Init session. Empties the user data and assigns the system object (phpbb::$instances['system'])
        * @access public
        */
        public function __construct()
        {
                // Reset data array ;)
                $this->data = array();

                // Set auth to false (only valid for an user object)
                $this->auth = false;

                // Some system/server variables, directly generated by phpbb_system methods. Used like an array.
                // We use the phpbb:: one, because it could've been modified and being a completely different class
                $this->system = &phpbb::$instances['system'];
        }

        /**
        * Specifiy the need for a session id within the URL
        *
        * @param bool   $need_sid       Specify if the session id is needed or not. Default is false.
        * @access public
        */
        public function need_sid($need_sid = false)
        {
                $this->need_sid = $need_sid;
        }

        /**
        * Start session management
        *
        * This is where all session activity begins. We gather various pieces of
        * information from the client and server. We test to see if a session already
        * exists. If it does, fine and dandy. If it doesn't we'll go on to create a
        * new one ... pretty logical heh? We also examine the system load (if we're
        * running on a system which makes such information readily available) and
        * halt if it's above an admin definable limit.
        *
        * @param bool   $update_session_page    If true the session page gets updated.
        *                                                                               This can be set to false to circumvent certain scripts to update the users last visited page.
        *
        * @return bool  True if the session exist or has been created, else False.
        * @access public
        */
        public function session_begin($update_session_page = true)
        {
                // Give us some basic information
                $this->time_now                         = time();
                $this->cookie_data                      = array('u' => 0, 'k' => '');
                $this->update_session_page      = $update_session_page;

                if (request::is_set(phpbb::$config['cookie_name'] . '_sid', request::COOKIE) || request::is_set(phpbb::$config['cookie_name'] . '_u', request::COOKIE))
                {
                        $this->cookie_data['u'] = request_var(phpbb::$config['cookie_name'] . '_u', 0, false, true);
                        $this->cookie_data['k'] = request_var(phpbb::$config['cookie_name'] . '_k', '', false, true);
                        $this->session_id               = request_var(phpbb::$config['cookie_name'] . '_sid', '', false, true);

                        if (empty($this->session_id))
                        {
                                $this->session_id = request_var('sid', '');
                                $this->cookie_data = array('u' => 0, 'k' => '');
                                $this->need_sid = true;
                        }
                }
                else
                {
                        $this->session_id = request_var('sid', '');
                        $this->need_sid = true;
                }

                $this->extra_url = array();

                // Now check for an existing session
                if ($this->session_exist())
                {
                        return true;
                }

                // If we reach here then no (valid) session exists. So we'll create a new one
                return $this->session_create();
        }

        /**
        * Create a new session
        *
        * If upon trying to start a session we discover there is nothing existing we
        * jump here. Additionally this method is called directly during login to regenerate
        * the session for the specific user. In this method we carry out a number of tasks;
        * garbage collection, (search)bot checking, banned user comparison. Basically
        * though this method will result in a new session for a specific user.
        *
        * @param int    $user_id                The user id to create the session for.
        * @param bool   $set_admin              Set the users admin field to identify him/her as an admin?
        * @param bool   $persist_login  Allow persistent login
        * @param bool   $viewonline             If false then the user will be logged in as hidden
        *
        * @return bool  True if session got created successfully.
        * @access public
        */
        public function session_create($user_id = false, $set_admin = false, $persist_login = false, $viewonline = true)
        {
                // There is one case where we need to add a "failsafe" user... when we are not able to query the database
                if (!phpbb::registered('db'))
                {
                        $this->data = $this->default_data();
                        return true;
                }

                // If the data array is filled, chances are high that there was a different session active
                if (sizeof($this->data))
                {
                        // Kill the session and do not create a new one
                        $this->session_kill(false);
                }

                $this->data = array();

                // Do we allow autologin on this board? No? Then override anything
                // that may be requested here
                if (!phpbb::$config['allow_autologin'])
                {
                        $this->cookie_data['k'] = $persist_login = false;
                }

                // Check for autologin key. ;)
                if ($this->auth !== false && method_exists($this->auth, 'autologin'))
                {
                        $this->data = $this->auth->autologin();

                        if (sizeof($this->data))
                        {
                                $this->cookie_data['k'] = '';
                                $this->cookie_data['u'] = $this->data['user_id'];
                        }
                }

                // NULL indicates we need to check for a bot later. Sometimes it is apparant that it is not a bot. ;) No need to always check this.
                $bot = NULL;

                // If we're presented with an autologin key we'll join against it.
                // Else if we've been passed a user_id we'll grab data based on that
                if (isset($this->cookie_data['k']) && $this->cookie_data['k'] && $this->cookie_data['u'] && !sizeof($this->data))
                {
                        $sql = 'SELECT u.*
                                FROM ' . USERS_TABLE . ' u, ' . SESSIONS_KEYS_TABLE . ' k
                                WHERE u.user_id = ' . (int) $this->cookie_data['u'] . '
                                        AND u.user_type IN (' . USER_NORMAL . ', ' . USER_FOUNDER . ")
                                        AND k.user_id = u.user_id
                                        AND k.key_id = '" . phpbb::$db->sql_escape(md5($this->cookie_data['k'])) . "'";
                        $result = phpbb::$db->sql_query($sql);
                        $this->data = phpbb::$db->sql_fetchrow($result);
                        phpbb::$db->sql_freeresult($result);

                        $bot = false;
                }
                else if ($user_id !== false && !sizeof($this->data))
                {
                        $this->cookie_data['k'] = '';
                        $this->cookie_data['u'] = $user_id;

                        $sql = 'SELECT *
                                FROM ' . USERS_TABLE . '
                                WHERE user_id = ' . (int) $this->cookie_data['u'] . '
                                        AND user_type IN (' . USER_NORMAL . ', ' . USER_FOUNDER . ')';
                        $result = phpbb::$db->sql_query($sql);
                        $this->data = phpbb::$db->sql_fetchrow($result);
                        phpbb::$db->sql_freeresult($result);

                        $bot = false;
                }

                if ($bot === NULL)
                {
                        $bot = $this->check_bot();
                }

                // If no data was returned one or more of the following occurred:
                // Key didn't match one in the DB
                // User does not exist
                // User is inactive
                // User is bot
                if (!sizeof($this->data) || !is_array($this->data))
                {
                        $this->cookie_data['k'] = '';
                        $this->cookie_data['u'] = ($bot) ? $bot : ANONYMOUS;

                        if (!$bot)
                        {
                                $sql = 'SELECT *
                                        FROM ' . USERS_TABLE . '
                                        WHERE user_id = ' . (int) $this->cookie_data['u'];
                        }
                        else
                        {
                                // We give bots always the same session if it is not yet expired.
                                $sql = 'SELECT u.*, s.*
                                        FROM ' . USERS_TABLE . ' u
                                        LEFT JOIN ' . SESSIONS_TABLE . ' s ON (s.session_user_id = u.user_id)
                                        WHERE u.user_id = ' . (int) $bot;
                        }

                        $result = phpbb::$db->sql_query($sql);
                        $this->data = phpbb::$db->sql_fetchrow($result);
                        phpbb::$db->sql_freeresult($result);

                        $this->is_registered = false;
                }
                else
                {
                        $this->is_registered = true;
                }

                // Force user id to be integer...
                $this->data['user_id'] = (int) $this->data['user_id'];

                // Code for ANONYMOUS user, INACTIVE user and BOTS
                if (!$this->is_registered)
                {
                        // Set last visit date to 'now'
                        $this->data['session_last_visit'] = $this->time_now;
                        $this->is_bot = ($bot) ? true : false;

                        // If our friend is a bot, we re-assign a previously assigned session
                        if ($this->is_bot && $bot == $this->data['user_id'] && $this->data['session_id'])
                        {
                                if ($this->session_valid(false))
                                {
                                        $this->session_id = $this->data['session_id'];

                                        // Only update session DB a minute or so after last update or if page changes
                                        if ($this->time_now - $this->data['session_time'] > 60 || ($this->update_session_page && $this->data['session_page'] != $this->system['page']['page']))
                                        {
                                                $this->data['session_time'] = $this->data['session_last_visit'] = $this->time_now;
                                                $sql_ary = array('session_time' => $this->time_now, 'session_last_visit' => $this->time_now, 'session_admin' => 0);

                                                if ($this->update_session_page)
                                                {
                                                        $sql_ary['session_page'] = substr($this->system['page']['page'], 0, 199);
                                                }

                                                $sql = 'UPDATE ' . SESSIONS_TABLE . ' SET ' . phpbb::$db->sql_build_array('UPDATE', $sql_ary) . "
                                                        WHERE session_id = '" . phpbb::$db->sql_escape($this->session_id) . "'";
                                                phpbb::$db->sql_query($sql);

                                                // Update the last visit time
                                                $sql = 'UPDATE ' . USERS_TABLE . '
                                                        SET user_lastvisit = ' . (int) $this->data['session_time'] . '
                                                        WHERE user_id = ' . (int) $this->data['user_id'];
                                                phpbb::$db->sql_query($sql);
                                        }

                                        $this->session_id = '';

                                        return true;
                                }
                                else
                                {
                                        // If the ip and browser does not match make sure we only have one bot assigned to one session
                                        phpbb::$db->sql_query('DELETE FROM ' . SESSIONS_TABLE . ' WHERE session_user_id = ' . $this->data['user_id']);
                                }
                        }
                }
                else
                {
                        // Code for registered users
                        $this->data['session_last_visit'] = (!empty($this->data['session_time'])) ? $this->data['session_time'] : (($this->data['user_lastvisit']) ? $this->data['user_lastvisit'] : $this->time_now);
                        $this->is_bot = false;
                }

                // At this stage we should have a filled data array, defined cookie u and k data.
                // data array should contain recent session info if we're a real user and a recent
                // session exists in which case session_id will also be set

                // Is user banned? Are they excluded? Won't return on ban, exists within method
                if ($this->data['user_type'] != USER_FOUNDER)
                {
                        if (!phpbb::$config['forwarded_for_check'])
                        {
                                $this->check_ban($this->data['user_id'], $this->system['ip']);
                        }
                        else
                        {
                                $ips = explode(', ', $this->forwarded_for);
                                $ips[] = $this->system['ip'];
                                $this->check_ban($this->data['user_id'], $ips);
                        }
                }

                $session_autologin = (($this->cookie_data['k'] || $persist_login) && $this->is_registered) ? true : false;
                $set_admin = ($set_admin && $this->is_registered) ? true : false;

                // Create or update the session
                $sql_ary = array(
                        'session_user_id'               => (int) $this->data['user_id'],
                        'session_start'                 => (int) $this->time_now,
                        'session_last_visit'    => (int) $this->data['session_last_visit'],
                        'session_time'                  => (int) $this->time_now,
                        'session_browser'               => (string) trim(substr($this->system['browser'], 0, 149)),
                        'session_forwarded_for' => (string) $this->system['forwarded_for'],
                        'session_ip'                    => (string) $this->system['ip'],
                        'session_autologin'             => ($session_autologin) ? 1 : 0,
                        'session_admin'                 => ($set_admin) ? 1 : 0,
                        'session_viewonline'    => ($viewonline) ? 1 : 0,
                );

                if ($this->update_session_page)
                {
                        $sql_ary['session_page'] = (string) substr($this->system['page']['page'], 0, 199);
                }

                phpbb::$db->sql_return_on_error(true);

                // Delete old session, if user id now different from anonymous
                if (!defined('IN_ERROR_HANDLER'))
                {
                        // We do not care about the user id, because we assign a new session later
                        $sql = 'DELETE
                                FROM ' . SESSIONS_TABLE . "
                                WHERE session_id = '" . phpbb::$db->sql_escape($this->session_id) . "'";
                        $result = phpbb::$db->sql_query($sql);

                        // If there were no sessions or the session id empty (then the affected rows will be empty too), then we have a brand new session and can check the active sessions limit
                        if ((!$result || !phpbb::$db->sql_affectedrows()) && (empty($this->data['session_time']) && phpbb::$config['active_sessions']))
                        {
                                $sql = 'SELECT COUNT(session_id) AS sessions
                                        FROM ' . SESSIONS_TABLE . '
                                        WHERE session_time >= ' . ($this->time_now - 60);
                                $result = phpbb::$db->sql_query($sql);
                                $row = phpbb::$db->sql_fetchrow($result);
                                phpbb::$db->sql_freeresult($result);

                                if ((int) $row['sessions'] > (int) phpbb::$config['active_sessions'])
                                {
                                        header('HTTP/1.1 503 Service Unavailable');
                                        trigger_error('BOARD_UNAVAILABLE');
                                }
                        }
                }

                $this->session_id = $this->data['session_id'] = md5(phpbb::$security->unique_id());

                $sql_ary['session_id'] = (string) $this->session_id;

                $sql = 'INSERT INTO ' . SESSIONS_TABLE . ' ' . phpbb::$db->sql_build_array('INSERT', $sql_ary);
                phpbb::$db->sql_query($sql);

                phpbb::$db->sql_return_on_error(false);

                // Regenerate autologin/persistent login key
                if ($session_autologin)
                {
                        $this->set_login_key();
                }

                // refresh data
                $this->data = array_merge($this->data, $sql_ary);

                if (!$bot)
                {
                        $cookie_expire = $this->time_now + ((phpbb::$config['max_autologin_time']) ? 86400 * (int) phpbb::$config['max_autologin_time'] : 31536000);

                        $this->set_cookie('u', $this->cookie_data['u'], $cookie_expire);
                        $this->set_cookie('k', $this->cookie_data['k'], $cookie_expire);
                        $this->set_cookie('sid', $this->session_id, $cookie_expire);

                        unset($cookie_expire);

                        // Only one session entry present...
                        $sql = 'SELECT COUNT(session_id) AS sessions
                                FROM ' . SESSIONS_TABLE . '
                                WHERE session_user_id = ' . (int) $this->data['user_id'] . '
                                        AND session_time >= ' . (int) ($this->time_now - (max(phpbb::$config['session_length'], phpbb::$config['form_token_lifetime'])));
                        $result = phpbb::$db->sql_query($sql);
                        $row = phpbb::$db->sql_fetchrow($result);
                        phpbb::$db->sql_freeresult($result);

                        if ((int) $row['sessions'] <= 1 || empty($this->data['user_form_salt']))
                        {
                                $this->data['user_form_salt'] = phpbb::$security->unique_id();

                                // Update the form key
                                $sql = 'UPDATE ' . USERS_TABLE . '
                                        SET user_form_salt = \'' . phpbb::$db->sql_escape($this->data['user_form_salt']) . '\'
                                        WHERE user_id = ' . (int) $this->data['user_id'];
                                phpbb::$db->sql_query($sql);
                        }
                }
                else
                {
                        $this->data['session_time'] = $this->data['session_last_visit'] = $this->time_now;

                        // Update the last visit time
                        $sql = 'UPDATE ' . USERS_TABLE . '
                                SET user_lastvisit = ' . (int) $this->data['session_time'] . '
                                WHERE user_id = ' . (int) $this->data['user_id'];
                        phpbb::$db->sql_query($sql);

                        $this->session_id = '';
                }

                return true;
        }

        /**
        * Kills a session
        *
        * This method does what it says on the tin. It will delete a pre-existing session.
        * It resets cookie information (destroying any autologin key within that cookie data)
        * and update the users information from the relevant session data. It will then
        * grab guest user information.
        *
        * @param bool   $new_session    If true a new session will be generated after the original one got killed.
        * @access public
        */
        public function session_kill($new_session = true)
        {
                $sql = 'DELETE FROM ' . SESSIONS_TABLE . "
                        WHERE session_id = '" . phpbb::$db->sql_escape($this->session_id) . "'
                                AND session_user_id = " . (int) $this->data['user_id'];
                phpbb::$db->sql_query($sql);

                // Allow connecting logout with external auth method logout
                if ($this->auth !== false && method_exists($this->auth, 'logout'))
                {
                        $this->auth->logout($this, $new_session);
                }

                if ($this->data['user_id'] != ANONYMOUS)
                {
                        // Delete existing session, update last visit info first!
                        if (!isset($this->data['session_time']))
                        {
                                $this->data['session_time'] = time();
                        }

                        $sql = 'UPDATE ' . USERS_TABLE . '
                                SET user_lastvisit = ' . (int) $this->data['session_time'] . '
                                WHERE user_id = ' . (int) $this->data['user_id'];
                        phpbb::$db->sql_query($sql);

                        if ($this->cookie_data['k'])
                        {
                                $sql = 'DELETE FROM ' . SESSIONS_KEYS_TABLE . '
                                        WHERE user_id = ' . (int) $this->data['user_id'] . "
                                                AND key_id = '" . phpbb::$db->sql_escape(md5($this->cookie_data['k'])) . "'";
                                phpbb::$db->sql_query($sql);
                        }

                        // Reset the data array
                        $this->data = array();

                        $sql = 'SELECT *
                                FROM ' . USERS_TABLE . '
                                WHERE user_id = ' . ANONYMOUS;
                        $result = phpbb::$db->sql_query($sql);
                        $this->data = phpbb::$db->sql_fetchrow($result);
                        phpbb::$db->sql_freeresult($result);
                }

                $cookie_expire = $this->time_now - 31536000;
                $this->set_cookie('u', '', $cookie_expire);
                $this->set_cookie('k', '', $cookie_expire);
                $this->set_cookie('sid', '', $cookie_expire);
                unset($cookie_expire);

                $this->session_id = '';

                // To make sure a valid session is created we create one for the anonymous user
                if ($new_session)
                {
                        $this->session_create(ANONYMOUS);
                }
        }

        /**
        * Session garbage collection
        *
        * This looks a lot more complex than it really is. Effectively we are
        * deleting any sessions older than an admin definable limit. Due to the
        * way in which we maintain session data we have to ensure we update user
        * data before those sessions are destroyed. In addition this method
        * removes autologin key information that is older than an admin defined
        * limit.
        *
        * @access public
        */
        public function session_gc()
        {
                $batch_size = 10;

                if (!$this->time_now)
                {
                        $this->time_now = time();
                }

                // Firstly, delete guest sessions
                $sql = 'DELETE FROM ' . SESSIONS_TABLE . '
                        WHERE session_user_id = ' . ANONYMOUS . '
                                AND session_time < ' . (int) ($this->time_now - phpbb::$config['session_length']);
                phpbb::$db->sql_query($sql);

                // Get expired sessions, only most recent for each user
                $sql = 'SELECT session_user_id, session_page, MAX(session_time) AS recent_time
                        FROM ' . SESSIONS_TABLE . '
                        WHERE session_time < ' . ($this->time_now - phpbb::$config['session_length']) . '
                        GROUP BY session_user_id, session_page';
                $result = phpbb::$db->sql_query_limit($sql, $batch_size);

                $del_user_id = array();
                $del_sessions = 0;

                while ($row = phpbb::$db->sql_fetchrow($result))
                {
                        $sql = 'UPDATE ' . USERS_TABLE . '
                                SET user_lastvisit = ' . (int) $row['recent_time'] . ", user_lastpage = '" . phpbb::$db->sql_escape($row['session_page']) . "'
                                WHERE user_id = " . (int) $row['session_user_id'];
                        phpbb::$db->sql_query($sql);

                        $del_user_id[] = (int) $row['session_user_id'];
                        $del_sessions++;
                }
                phpbb::$db->sql_freeresult($result);

                if (sizeof($del_user_id))
                {
                        // Delete expired sessions
                        $sql = 'DELETE FROM ' . SESSIONS_TABLE . '
                                WHERE ' . phpbb::$db->sql_in_set('session_user_id', $del_user_id) . '
                                        AND session_time < ' . ($this->time_now - phpbb::$config['session_length']);
                        phpbb::$db->sql_query($sql);
                }

                if ($del_sessions < $batch_size)
                {
                        // Less than 10 users, update gc timer ... else we want gc
                        // called again to delete other sessions
                        set_config('session_last_gc', $this->time_now, true);

                        if (phpbb::$config['max_autologin_time'])
                        {
                                $sql = 'DELETE FROM ' . SESSIONS_KEYS_TABLE . '
                                        WHERE last_login < ' . (time() - (86400 * (int) phpbb::$config['max_autologin_time']));
                                phpbb::$db->sql_query($sql);
                        }

                        // only called from CRON; should be a safe workaround until the infrastructure gets going
                        if (!class_exists('captcha_factory'))
                        {
                                include(PHPBB_ROOT_PATH . "includes/captcha/captcha_factory." . PHP_EXT);
                        }
                        captcha_factory::garbage_collect(phpbb::$config['captcha_plugin']);
                }

                return;
        }


        /**
        * Sets a cookie of the given name with the specified data for the given length of time. If no time is specified, a session cookie will be set.
        *
        * @param string $name           Name of the cookie, will be automatically prefixed with the phpBB cookie name. Track becomes [cookie_name]_track then.
        * @param string $cookiedata     The data to hold within the cookie
        * @param int    $cookietime     The expiration time as UNIX timestamp. If 0 is provided, a session cookie is set.
        *
        * @access public
        */
        public function set_cookie($name, $cookiedata, $cookietime)
        {
                $name_data = rawurlencode(phpbb::$config['cookie_name'] . '_' . $name) . '=' . rawurlencode($cookiedata);
                $expire = gmdate('D, d-M-Y H:i:s \\G\\M\\T', $cookietime);
                $domain = (!phpbb::$config['cookie_domain'] || phpbb::$config['cookie_domain'] == 'localhost' || phpbb::$config['cookie_domain'] == '127.0.0.1') ? '' : '; domain=' . phpbb::$config['cookie_domain'];

                header('Set-Cookie: ' . $name_data . (($cookietime) ? '; expires=' . $expire : '') . '; path=' . phpbb::$config['cookie_path'] . $domain . ((!phpbb::$config['cookie_secure']) ? '' : '; secure') . '; HttpOnly', false);
        }

        /**
        * Check for banned user
        *
        * Checks whether the supplied user is banned by id, ip or email. If no parameters
        * are passed to the method pre-existing session data is used. If $return is false
        * this routine does not return on finding a banned user, it outputs a relevant
        * message and stops execution.
        *
        * @param int                    $user_id        The user id to check. If false then do not check user ids
        * @param string|array   $user_ips       Can contain a string with one IP or an array of multiple IPs. If false then no ips are checked.
        * @param int                    $user_email     The email address to check
        * @param bool                   $return         If false then the banned message is displayed and script halted
        *
        * @return bool|string   True if banned and no reason given.
        *                                               False if not banned. A ban reason if banned and ban reason given. Check for !== false.
        * @access public
        */
        public function check_ban($user_id = false, $user_ips = false, $user_email = false, $return = false)
        {
                if (defined('IN_CHECK_BAN'))
                {
                        return;
                }

                $banned = false;
                $cache_ttl = 3600;
                $where_sql = array();

                $sql = 'SELECT ban_ip, ban_userid, ban_email, ban_exclude, ban_give_reason, ban_end
                        FROM ' . BANLIST_TABLE . '
                        WHERE ';

                // Determine which entries to check, only return those
                if ($user_email === false)
                {
                        $where_sql[] = "ban_email = ''";
                }

                if ($user_ips === false)
                {
                        $where_sql[] = "(ban_ip = '' OR ban_exclude = 1)";
                }

                if ($user_id === false)
                {
                        $where_sql[] = '(ban_userid = 0 OR ban_exclude = 1)';
                }
                else
                {
                        $cache_ttl = ($user_id == ANONYMOUS) ? 3600 : 0;
                        $_sql = '(ban_userid = ' . $user_id;

                        if ($user_email !== false)
                        {
                                $_sql .= " OR ban_email <> ''";
                        }

                        if ($user_ips !== false)
                        {
                                $_sql .= " OR ban_ip <> ''";
                        }

                        $_sql .= ')';

                        $where_sql[] = $_sql;
                }

                $sql .= (sizeof($where_sql)) ? implode(' AND ', $where_sql) : '';
                $result = phpbb::$db->sql_query($sql, $cache_ttl);

                $ban_triggered_by = 'user';
                while ($row = phpbb::$db->sql_fetchrow($result))
                {
                        if ($row['ban_end'] && $row['ban_end'] < time())
                        {
                                continue;
                        }

                        $ip_banned = false;
                        if (!empty($row['ban_ip']))
                        {
                                if (!is_array($user_ips))
                                {
                                        $ip_banned = preg_match('#^' . str_replace('\*', '.*?', preg_quote($row['ban_ip'], '#')) . '$#i', $user_ips);
                                }
                                else
                                {
                                        foreach ($user_ips as $user_ip)
                                        {
                                                if (preg_match('#^' . str_replace('\*', '.*?', preg_quote($row['ban_ip'], '#')) . '$#i', $user_ip))
                                                {
                                                        $ip_banned = true;
                                                        break;
                                                }
                                        }
                                }
                        }

                        if ((!empty($row['ban_userid']) && intval($row['ban_userid']) == $user_id) ||
                                $ip_banned ||
                                (!empty($row['ban_email']) && preg_match('#^' . str_replace('\*', '.*?', preg_quote($row['ban_email'], '#')) . '$#i', $user_email)))
                        {
                                if (!empty($row['ban_exclude']))
                                {
                                        $banned = false;
                                        break;
                                }
                                else
                                {
                                        $banned = true;
                                        $ban_row = $row;

                                        if (!empty($row['ban_userid']) && intval($row['ban_userid']) == $user_id)
                                        {
                                                $ban_triggered_by = 'user';
                                        }
                                        else if ($ip_banned)
                                        {
                                                $ban_triggered_by = 'ip';
                                        }
                                        else
                                        {
                                                $ban_triggered_by = 'email';
                                        }

                                        // Don't break. Check if there is an exclude rule for this user
                                }
                        }
                }
                phpbb::$db->sql_freeresult($result);

                if ($banned && !$return)
                {
                        // If the session is empty we need to create a valid one...
                        if (empty($this->session_id))
                        {
                                // This seems to be no longer needed? - #14971
//                              $this->session_create(ANONYMOUS);
                        }

                        // Initiate environment ... since it won't be set at this stage
                        $this->setup();

                        // Logout the user, banned users are unable to use the normal 'logout' link
                        if ($this->data['user_id'] != ANONYMOUS)
                        {
                                $this->session_kill();
                        }

                        // We show a login box here to allow founders accessing the board if banned by IP
                        if (defined('IN_LOGIN') && $this->data['user_id'] == ANONYMOUS)
                        {
                                $this->setup('ucp');
                                $this->is_registered = $this->is_bot = false;

                                // Set as a precaution to allow login_box() handling this case correctly as well as this function not being executed again.
                                define('IN_CHECK_BAN', 1);

                                login_box('index.' . PHP_EXT);

                                // The false here is needed, else the user is able to circumvent the ban.
                                $this->session_kill(false);
                        }

                        // Ok, we catch the case of an empty session id for the anonymous user...
                        // This can happen if the user is logging in, banned by username and the login_box() being called "again".
                        if (empty($this->session_id) && defined('IN_CHECK_BAN'))
                        {
                                $this->session_create(ANONYMOUS);
                        }


                        // Determine which message to output
                        $till_date = ($ban_row['ban_end']) ? $this->format_date($ban_row['ban_end']) : '';
                        $message = ($ban_row['ban_end']) ? 'BOARD_BAN_TIME' : 'BOARD_BAN_PERM';

                        $message = sprintf($this->lang[$message], $till_date, '<a href="mailto:' . phpbb::$config['board_contact'] . '">', '</a>');
                        $message .= ($ban_row['ban_give_reason']) ? '<br /><br />' . sprintf($this->lang['BOARD_BAN_REASON'], $ban_row['ban_give_reason']) : '';
                        $message .= '<br /><br /><em>' . $this->lang['BAN_TRIGGERED_BY_' . strtoupper($ban_triggered_by)] . '</em>';

                        // To circumvent session_begin returning a valid value and the check_ban() not called on second page view, we kill the session again
                        $this->session_kill(false);

                        // A very special case... we are within the cron script which is not supposed to print out the ban message... show blank page
                        if (defined('IN_CRON'))
                        {
                                garbage_collection();
                                exit_handler();
                                exit;
                        }

                        trigger_error($message);
                }

                return ($banned && $ban_row['ban_give_reason']) ? $ban_row['ban_give_reason'] : $banned;
        }

        /**
        * Check if ip is blacklisted
        * This should be called only where absolutly necessary
        *
        * Only IPv4 (rbldns does not support AAAA records/IPv6 lookups)
        *
        * @param string $mode   Possible modes are: register and post
        *                                               spamhaus.org is used for both modes. Spamcop.net is additionally used for register.
        * @param string $ip             The ip to check. If false then the current IP is used
        *
        * @return bool|array    False if ip is not blacklisted, else an array([checked server], [lookup])
        * @author satmd (from the php manual)
        * @access public
        */
        public function check_dnsbl($mode, $ip = false)
        {
                if ($ip === false)
                {
                        $ip = $this->system['ip'];
                }

                $dnsbl_check = array(
                        'sbl-xbl.spamhaus.org'  => 'http://www.spamhaus.org/query/bl?ip=',
                );

                if ($mode == 'register')
                {
                        $dnsbl_check['bl.spamcop.net'] = 'http://spamcop.net/bl.shtml?';
                }

                if ($ip)
                {
                        $quads = explode('.', $ip);
                        $reverse_ip = $quads[3] . '.' . $quads[2] . '.' . $quads[1] . '.' . $quads[0];

                        // Need to be listed on all servers...
                        $listed = true;
                        $info = array();

                        foreach ($dnsbl_check as $dnsbl => $lookup)
                        {
                                if (phpbb_checkdnsrr($reverse_ip . '.' . $dnsbl . '.', 'A') === true)
                                {
                                        $info = array($dnsbl, $lookup . $ip);
                                }
                                else
                                {
                                        $listed = false;
                                }
                        }

                        if ($listed)
                        {
                                return $info;
                        }
                }

                return false;
        }

        /**
        * Set/Update a persistent login key
        *
        * This method creates or updates a persistent session key. When a user makes
        * use of persistent (formerly auto-) logins a key is generated and stored in the
        * DB. When they revisit with the same key it's automatically updated in both the
        * DB and cookie. Multiple keys may exist for each user representing different
        * browsers or locations. As with _any_ non-secure-socket no passphrase login this
        * remains vulnerable to exploit.
        *
        * @param int    $user_id        The user id. If false the current users user id will be used
        * @param string $key            A login key. If false then the current users login key stored within the cookie will be used
        * @param string $user_ip        The users ip. If false, then the current users IP will be used
        * @access public
        */
        public function set_login_key($user_id = false, $key = false, $user_ip = false)
        {
                $user_id = ($user_id === false) ? $this->data['user_id'] : $user_id;
                $user_ip = ($user_ip === false) ? $this->system['ip'] : $user_ip;
                $key = ($key === false) ? (($this->cookie_data['k']) ? $this->cookie_data['k'] : false) : $key;

                $key_id = phpbb::$security->unique_id(hexdec(substr($this->session_id, 0, 8)));

                $sql_ary = array(
                        'key_id'                => (string) md5($key_id),
                        'last_ip'               => (string) $this->system['ip'],
                        'last_login'    => (int) $this->time_now,
                );

                if (!$key)
                {
                        $sql_ary += array(
                                'user_id'       => (int) $user_id
                        );
                }

                if ($key)
                {
                        $sql = 'UPDATE ' . SESSIONS_KEYS_TABLE . '
                                SET ' . phpbb::$db->sql_build_array('UPDATE', $sql_ary) . '
                                WHERE user_id = ' . (int) $user_id . "
                                        AND key_id = '" . phpbb::$db->sql_escape(md5($key)) . "'";
                }
                else
                {
                        $sql = 'INSERT INTO ' . SESSIONS_KEYS_TABLE . ' ' . phpbb::$db->sql_build_array('INSERT', $sql_ary);
                }
                phpbb::$db->sql_query($sql);

                $this->cookie_data['k'] = $key_id;
        }

        /**
        * Reset all login keys for the specified user
        *
        * This method removes all current login keys for a specified (or the current)
        * user. It will be called on password change to render old keys unusable
        *
        * @param int    $user_id        The user id. If false then the current users user id is used.
        * @access public
        */
        public function reset_login_keys($user_id = false)
        {
                $user_id = ($user_id === false) ? $this->data['user_id'] : $user_id;

                $sql = 'DELETE FROM ' . SESSIONS_KEYS_TABLE . '
                        WHERE user_id = ' . (int) $user_id;
                phpbb::$db->sql_query($sql);

                // Let's also clear any current sessions for the specified user_id
                // If it's the current user then we'll leave this session intact
                $sql_where = 'session_user_id = ' . (int) $user_id;
                $sql_where .= ($user_id === $this->data['user_id']) ? " AND session_id <> '" . phpbb::$db->sql_escape($this->session_id) . "'" : '';

                $sql = 'DELETE FROM ' . SESSIONS_TABLE . "
                        WHERE $sql_where";
                phpbb::$db->sql_query($sql);

                // We're changing the password of the current user and they have a key
                // Lets regenerate it to be safe
                if ($user_id === $this->data['user_id'] && $this->cookie_data['k'])
                {
                        $this->set_login_key($user_id);
                }
        }

        /**
        * Reset all admin sessions
        *
        * @access public
        */
        public function unset_admin()
        {
                $sql = 'UPDATE ' . SESSIONS_TABLE . "
                        SET session_admin = 0
                        WHERE session_id = '" . phpbb::$db->sql_escape($this->session_id) . "'";
                phpbb::$db->sql_query($sql);
        }

        /**
        * Check if a valid, non-expired session exist. Also make sure it errors out correctly if we do not have a db-setup yet. ;)
        *
        * @return bool  True if a valid, non-expired session exist
        * @access private
        */
        private function session_exist()
        {
                // If session is empty or does not match the session within the URL (if required - set by NEED_SID), then we need a new session
                if (empty($this->session_id) || ($this->need_sid && $this->session_id !== request::variable('sid', '', false, request::GET)))
                {
                        return false;
                }

                // If the db is not initialized/registered, then we also need a new session (we are not able to go forward then...
                if (!phpbb::registered('db'))
                {
                        return false;
                }

                // Now finally check the db for our provided session
                $sql = 'SELECT u.*, s.*
                        FROM ' . SESSIONS_TABLE . ' s, ' . USERS_TABLE . " u
                        WHERE s.session_id = '" . phpbb::$db->sql_escape($this->session_id) . "'
                                AND u.user_id = s.session_user_id";
                $result = phpbb::$db->sql_query($sql);
                $row = phpbb::$db->sql_fetchrow($result);
                phpbb::$db->sql_freeresult($result);

                // Also new session if it has not been found. ;)
                if (!$row)
                {
                        return false;
                }

                $this->data = $row;

                // Now check the ip, the browser, forwarded for and referer
                if (!$this->session_valid())
                {
                        return false;
                }

                // Ok, we are not finished yet. We need to know if the session is expired

                // Check whether the session is still valid if we have one
                if ($this->auth !== false && method_exists($this->auth, 'validate_session'))
                {
                        if (!$this->auth->validate_session($this))
                        {
                                return false;
                        }
                }

                // Check the session length timeframe if autologin is not enabled.
                // Else check the autologin length... and also removing those having autologin enabled but no longer allowed board-wide.
                if (!$this->data['session_autologin'])
                {
                        if ($this->data['session_time'] < $this->time_now - (phpbb::$config['session_length'] + 60))
                        {
                                return false;
                        }
                }
                else if (!phpbb::$config['allow_autologin'] || (phpbb::$config['max_autologin_time'] && $this->data['session_time'] < $this->time_now - (86400 * (int) phpbb::$config['max_autologin_time']) + 60))
                {
                        return false;
                }

                // Only update session DB a minute or so after last update or if page changes
                if ($this->time_now - $this->data['session_time'] > 60 || ($this->update_session_page && $this->data['session_page'] != $this->system['page']['page']))
                {
                        $sql_ary = array('session_time' => $this->time_now);

                        if ($this->update_session_page)
                        {
                                $sql_ary['session_page'] = substr($this->system['page']['page'], 0, 199);
                                $sql_ary['session_forum_id'] = $this->system['page']['forum'];
                        }

                        $sql = 'UPDATE ' . SESSIONS_TABLE . ' SET ' . phpbb::$db->sql_build_array('UPDATE', $sql_ary) . "
                                WHERE session_id = '" . phpbb::$db->sql_escape($this->session_id) . "'";
                        phpbb::$db->sql_query($sql);
                }

                $this->is_registered = ($this->data['user_id'] != ANONYMOUS && ($this->data['user_type'] == USER_NORMAL || $this->data['user_type'] == USER_FOUNDER)) ? true : false;
                $this->is_bot = (!$this->is_registered && $this->data['user_id'] != ANONYMOUS) ? true : false;
                $this->data['user_lang'] = basename($this->data['user_lang']);

                return true;
        }

        /**
        * Check if the request originated from the same page.
        *
        * @param bool   $check_script_path      If true, the path will be checked as well
        *
        * @return bool  True if the referer is valid
        * @access private
        */
        private function validate_referer($check_script_path = false)
        {
                // no referer - nothing to validate, user's fault for turning it off (we only check on POST; so meta can't be the reason)
                if (empty($this->system['referer']) || empty($this->system['host']))
                {
                        return true;
                }

                // Specialchar host, because it's the only one not specialchared
                $host = htmlspecialchars($this->system['host']);
                $ref = substr($this->system['referer'], strpos($this->system['referer'], '://') + 3);

                if (!(stripos($ref, $host) === 0))
                {
                        return false;
                }
                else if ($check_script_path && rtrim($this->system['page']['root_script_path'], '/') !== '')
                {
                        $ref = substr($ref, strlen($host));
                        $server_port = $this->system['port'];

                        if ($server_port !== 80 && $server_port !== 443 && stripos($ref, ":$server_port") === 0)
                        {
                                $ref = substr($ref, strlen(":$server_port"));
                        }

                        if (!(stripos(rtrim($ref, '/'), rtrim($this->system['page']['root_script_path'], '/')) === 0))
                        {
                                return false;
                        }
                }

                return true;
        }

        /**
        * Fill data array with a "faked" user account
        *
        * @return array Default user data array
        * @access private
        */
        private function default_data()
        {
                return array(
                        'user_id'               => ANONYMOUS,
                );
        }

        /**
        * Check for a bot by comparing user agent and ip
        *
        * Here we do a bot check, oh er saucy! No, not that kind of bot
        * check. We loop through the list of bots defined by the admin and
        * see if we have any useragent and/or IP matches. If we do, this is a
        * bot, act accordingly
        *
        * @return bool  True if it is a bot.
        * @access private
        */
        private function check_bot()
        {
                $bot = false;

                foreach (phpbb_cache::obtain_bots() as $row)
                {
                        if ($row['bot_agent'] && preg_match('#' . str_replace('\*', '.*?', preg_quote($row['bot_agent'], '#')) . '#i', $this->system['browser']))
                        {
                                $bot = $row['user_id'];
                        }

                        // If ip is supplied, we will make sure the ip is matching too...
                        if ($row['bot_ip'] && ($bot || !$row['bot_agent']))
                        {
                                // Set bot to false, then we only have to set it to true if it is matching
                                $bot = false;

                                foreach (explode(',', $row['bot_ip']) as $bot_ip)
                                {
                                        if (strpos($this->system['ip'], $bot_ip) === 0)
                                        {
                                                $bot = (int) $row['user_id'];
                                                break;
                                        }
                                }
                        }

                        if ($bot)
                        {
                                break;
                        }
                }

                return $bot;
        }

        /**
        * Check if session is valid by comparing ip, forwarded for, browser and referer
        *
        * @param bool   $log_failure If true then a non-match will be logged. Can cause huge logs.
        *
        * @return bool  True if the session is valid
        * @access private
        */
        private function session_valid($log_failure = true)
        {
                // Validate IP length according to admin ... enforces an IP
                // check on bots if admin requires this
//              $quadcheck = (phpbb::$config['ip_check_bot'] && $this->data['user_type'] & USER_BOT) ? 4 : phpbb::$config['ip_check'];

                if (strpos($this->system['ip'], ':') !== false && strpos($this->data['session_ip'], ':') !== false)
                {
                        $session_ip = short_ipv6($this->data['session_ip'], phpbb::$config['ip_check']);
                        $user_ip = short_ipv6($this->system['ip'], phpbb::$config['ip_check']);
                }
                else
                {
                        $session_ip = implode('.', array_slice(explode('.', $this->data['session_ip']), 0, phpbb::$config['ip_check']));
                        $user_ip = implode('.', array_slice(explode('.', $this->system['ip']), 0, phpbb::$config['ip_check']));
                }

                $session_browser = (phpbb::$config['browser_check']) ? trim(strtolower(substr($this->data['session_browser'], 0, 149))) : '';
                $user_browser = (phpbb::$config['browser_check']) ? trim(strtolower(substr($this->system['browser'], 0, 149))) : '';

                $session_forwarded_for = (phpbb::$config['forwarded_for_check']) ? substr($this->data['session_forwarded_for'], 0, 254) : '';
                $user_forwarded_for = (phpbb::$config['forwarded_for_check']) ? substr($this->system['forwarded_for'], 0, 254) : '';

                // referer checks
                $check_referer_path = phpbb::$config['referer_validation'] == REFERER_VALIDATE_PATH;
                $referer_valid = true;

                // we assume HEAD and TRACE to be foul play and thus only whitelist GET
                if (phpbb::$config['referer_validation'] && $this->system['request_method'])
                {
                        $referer_valid = $this->validate_referer($check_referer_path);
                }

                if ($user_ip !== $session_ip || $user_browser !== $session_browser || $user_forwarded_for !== $session_forwarded_for || !$referer_valid)
                {
                        // Added logging temporarly to help debug bugs...
                        if (defined('DEBUG_EXTRA') && $this->data['user_id'] != ANONYMOUS && $log_failure)
                        {
                                if ($referer_valid)
                                {
                                        add_log('critical', 'LOG_IP_BROWSER_FORWARDED_CHECK', $user_ip, $session_ip, $user_browser, $session_browser, htmlspecialchars($user_forwarded_for), htmlspecialchars($session_forwarded_for));
                                }
                                else
                                {
                                        add_log('critical', 'LOG_REFERER_INVALID', $this->system['referer']);
                                }
                        }

                        return false;
                }

                return true;
        }
}

?>