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<?php

// ------------------------------------------------------------------------ //
// XOOPS - PHP Content Management System //
// Copyright (c) 2000 XOOPS.org //
// <http://www.xoops.org/> //
// ------------------------------------------------------------------------ //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation; either version 2 of the License, or //
// (at your option) any later version. //
// //
// You may not change or alter any portion of this comment or credits //
// of supporting developers from this source code or any supporting //
// source code which is considered copyrighted (c) material of the //
// original comment or credit authors. //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program; if not, write to the Free Software //
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA //
// ------------------------------------------------------------------------ //
// Author: Kazumi Ono (AKA onokazu) //
// URL: http://www.myweb.ne.jp/, http://www.xoops.org/, http://jp.xoops.org/ //
// Project: The XOOPS Project //
// ------------------------------------------------------------------------- //
/**
 * Session Management
 *
 * @copyright http://www.impresscms.org/ The ImpressCMS Project
 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU General Public License (GPL)
 * @category ICMS
 * @package Core
 * @subpackage Session
 * @version SVN: $Id: Session.php 12313 2013-09-15 21:14:35Z skenow $
 */
/**
 * Handler for a session
 *
 * Based on SecureSession class
 * Written by Vagharshak Tozalakyan <vagh@armdex.com>
 * Released under GNU Public License
 *
 * @category ICMS
 * @package Session
 *
 * @author Kazumi Ono <onokazu@xoops.org>
 * @copyright copyright (c) 2000-2003 XOOPS.org
 */
class icms_core_Session {

    /**
     * Initialize the session service
     *
     * @return icms_core_Session
     */
    static public function service() {
        global $icmsConfig;
        $instance = new icms_core_Session(icms::$xoopsDB);
        session_set_save_handler(array($instance, 'open'), array($instance, 'close'), array($instance, 'read'),
            array($instance, 'write'), array($instance, 'destroy'), array($instance, 'gc'));
        $sslpost_name = isset($_POST[$icmsConfig['sslpost_name']]) ? $_POST[$icmsConfig['sslpost_name']] : "";
        $instance->sessionStart($sslpost_name);

        if (!empty($_SESSION['xoopsUserId'])) {
            $user = icms::handler('icms_member')->getUser($_SESSION['xoopsUserId']);
            if (!is_object($user)) {
                // Regenerate a new session id and destroy old session
                $instance->icms_sessionRegenerateId(true);
                $_SESSION = array();
            } else {
                icms::$user = $user;
                if ($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '') {
                    // we need to secure cookie when using SSL
                    $secure = substr(ICMS_URL, 0, 5) == 'https' ? 1 : 0;
                    icms_setCookieVar($icmsConfig['session_name'], session_id(), time() + (60 * $icmsConfig['session_expire']));
                }
                $user->setGroups($_SESSION['xoopsUserGroups']);
                if (!isset($_SESSION['UserLanguage']) || empty($_SESSION['UserLanguage'])) {
                    $_SESSION['UserLanguage'] = $user->getVar('language');
                }
            }
        }
        return $instance;
    }

    /**
     * Database connection
     *
     * @var object
     * @access private
     */
    private $db;
    private $mainSaltKey = XOOPS_DB_SALT;

    /**
     * Security checking level
     * Possible value:
     * 0 - no check;
     * 1 - check browser characteristics (HTTP_USER_AGENT);
     * 2 - check browser and IP A.B;
     * 3 - check browser and IP A.B.C, recommended;
     * 4 - check browser and IP A.B.C.D;
     *
     * @var int
     * @access public
     */
    public $securityLevel = 3;

    /**
     * Security checking level for IPv6 Address types
     * Possible value:
     * 0 - no check;
     * 1 - check browser characteristics (HTTP_USER_AGENT);
     * 2 - check browser and IPv6 aaaa:bbbb;
     * 3 - check browser and IPv6 aaaa:bbbb:cccc;
     * 4 - check browser and IPv6 aaaa:bbbb:cccc:dddd;
     * 5 - check browser and IPv6 aaaa:bbbb:cccc:dddd:eeee;
     * 6 - check browser and IPv6 aaaa:bbbb:cccc:dddd:eeee:ffff;
     * 7 - check browser and IPv6 aaaa:bbbb:cccc:dddd:eeee:ffff:gggg; (recommended)
     * 8 - check browser and IPv6 aaaa:bbbb:cccc:dddd:eeee:ffff:gggg:hhhh;
     *
     * @var int
     * @access public
     */
    public $ipv6securityLevel = 7;

    /**
     * Enable regenerate_id
     *
     * @var bool
     * @access public
     */
    public $enableRegenerateId = false;

    /**
     * Constructor
     *
     * @param object $db reference to the {@link XoopsDatabase} object
     *        Do we need this $db reference now we're using icms::$xoopsDB?????
     *
     */
    public function __construct(&$db) {
        $this->db = &$db;
    }

    /**
     * Open a session
     *
     * @param string $save_path
     * @param string $session_name
     * @return bool
     */
    public function open($save_path, $session_name) {
        return true;
    }

    /**
     * Close a session
     *
     * @return bool
     */
    public function close() {
        self::gc_force();
        return true;
    }

    /**
     * Read a session from the database
     *
     * @param string &sess_id ID of the session
     * @return string Session data
     */
    public function read($sess_id) {
        return self::readSession($sess_id);
    }

    /**
     * Inserts a session into the database
     *
     * @param string $sess_id
     * @param string $sess_data
     * @return bool
     */
    public function write($sess_id, $sess_data) {
        return (bool) self::writeSession($sess_id, $sess_data);
    }

    /**
     * Destroy a session
     *
     * @param string $sess_id
     * @return bool
     */
    public function destroy($sess_id) {
        return (bool) self::destroySession($sess_id);
    }

    /**
     * Garbage Collector
     *
     * @param int $expire Time in seconds until a session expires
     * @return bool
     */
    public function gc($expire) {
        return (bool) self::gcSession($expire);
    }

    /**
     * Force gc for situations where gc is registered but not executed
     */
    public function gc_force() {
        if (rand(1, 100) < 11) {
            $expiration = empty($GLOBALS['icmsConfig']['session_expire'])
                ? @ini_get('session.gc_maxlifetime')
                : $GLOBALS['icmsConfig']['session_expire'] * 60;
            $this->gc($expiration);
        }
    }

    /**
     * Update the current session id with a newly generated one
     * To be refactored
     *
     * @param bool $delete_old_session
     * @return bool
     */
    public function icms_sessionRegenerateId($regenerate = false) {
        $old_session_id = session_id();
        if ($regenerate) {
            $success = session_regenerate_id(true);
            // $this->destroy($old_session_id);
        } else {
            $success = session_regenerate_id();
        }
        // Force updating cookie for session cookie is not issued correctly in some IE versions,
        // or not automatically issued prior to PHP 4.3.3 for all browsers
        if ($success) {
            self::update_cookie();
        }
        return $success;
    }

    /**
     * Update cookie status for current session
     * To be refactored
     *
     * @param string $sess_id session ID
     * @param int $expire Time in seconds until a session expires
     * @return bool
     */
    public function update_cookie($sess_id = null, $expire = null) {
        global $icmsConfig;
        $secure = substr(ICMS_URL, 0, 5) == 'https' ? 1 : 0; // we need to secure cookie when using SSL
        $session_name = ($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '')
            ? $icmsConfig['session_name'] : session_name();
        $session_expire = $expire !== null
            ? (int) $expire
            : (($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '')
                ? $icmsConfig['session_expire'] * 60
                : ini_get('session.cookie_lifetime'));
        $session_id = empty($sess_id) ? session_id() : $sess_id;
        icms_setCookieVar($session_name, $session_id, $session_expire ? time() + $session_expire : 0);
    }

    /**
     * Creates a Fingerprint of the current User Session
     * Fingerprint stored in current $_SESSION['icms_fprint']
     * To be refactored
     *
     * @return string
     */
    public function createFingerprint() {
        $userAgent = $_SERVER['HTTP_USER_AGENT'];
        $userIP = $_SERVER['REMOTE_ADDR'];

        return self::sessionFingerprint($userIP, $userAgent);
    }

    /**
     * Compares the Fingerprint stored in $_SESSION['icms_fprint'] by creating a new Fingerprint.
     * If they match, the Session is valid.
     * To be refactored
     *
     * @return bool
     */
    public function checkFingerprint() {
        $userAgent = $_SERVER['HTTP_USER_AGENT'];
        $userIP = $_SERVER['REMOTE_ADDR'];
        $sessFprint = self::sessionFingerprint($userIP, $userAgent);

        if ($sessFprint == $_SESSION['icms_fprint']) {
            return true;
        } else {
            return false;
        }
    }

    // Call this when init session.
    public function sessionOpen($regenerate = false) {
        $_SESSION['icms_fprint'] = self::createFingerprint();
        if ($regenerate) {
            self::icms_sessionRegenerateId(true);
        }
    }

    public function removeExpiredCustomSession($sess) {
        global $icmsConfig;
        if ($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '' && !isset($_COOKIE[$icmsConfig['session_name']]) && !empty($_SESSION[$sess])) {
            unset($_SESSION[$sess]);
        }
    }

    /**
     * Closes the Session & removes Session Cookies for specified User Id
     * To be refactored
     *
     * @param string $uid User ID of user to close
     * @return
     */
    public function sessionClose($uid) {
        global $icmsConfig;

        $uid = (int) $uid;
        session_regenerate_id(true);
        $_SESSION = array();
        if ($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '') {
            icms_setCookieVar($icmsConfig['session_name'], '', time() - 3600);
        }
        // clear entry from online users table
        if ($uid > 0) {
            $online_handler = icms::handler('icms_core_Online');
            $online_handler->destroy($uid);
        }
        icms_Event::trigger('icms_core_Session', 'sessionClose', $this);
        return;
    }

    /**
     * Creates Session ID & Starts the session
     * removes Expired Custom Sessions after session Start
     *
     * @param string $sslpost_name sets the session_id as ssl Name defined in preferences (if SSL enabled)
     * @return
     */
    public function sessionStart($sslpost_name = '') {
        global $icmsConfig;

        if ($icmsConfig['use_ssl'] && isset($sslpost_name) && $sslpost_name != '') {
            session_id($sslpost_name);
        } elseif ($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '' && $icmsConfig['session_expire'] > 0) {
            if (isset($_COOKIE[$icmsConfig['session_name']])) {
                session_id($_COOKIE[$icmsConfig['session_name']]);
            }
            if (function_exists('session_cache_expire')) {
                session_cache_expire($icmsConfig['session_expire']);
            }
            @ini_set('session.gc_maxlifetime', $icmsConfig['session_expire'] * 60);
        }

        if ($icmsConfig['use_mysession'] && $icmsConfig['session_name'] != '') {
            session_name($icmsConfig['session_name']);
        } else {
            session_name('ICMSSESSION');
        }
        session_start();

        self::removeExpiredCustomSession('xoopsUserId');
        icms_Event::trigger('icms_core_Session', 'sessionStart', $this);
        return;
    }

    // Internal function. Returns sha256 from fingerprint.
    private function sessionFingerprint($ip, $userAgent) {
        $securityLevel = (int) $this->securityLevel;
        $ipv6securityLevel = (int) $this->ipv6securityLevel;

        $fingerprint = $this->mainSaltKey;

        if (isset($ip) && icms_core_DataFilter::checkVar($ip, 'ip', 'ipv4')) {
            if ($securityLevel >= 1) {
                $fingerprint .= $userAgent;
            }
            if ($securityLevel >= 2) {
                $num_blocks = abs($securityLevel);
                if ($num_blocks > 4) {
                    $num_blocks = 4;
                }
                $blocks = explode('.', $ip);
                for ($i = 0; $i < $num_blocks; $i++ ) {
                    $fingerprint .= $blocks[$i] . '.';
                }
            }
        } elseif (isset($ip) && icms_core_DataFilter::checkVar($ip, 'ip', 'ipv6')) {
            if ($securityLevel >= 1) {
                $fingerprint .= $userAgent;
            }
            if ($securityLevel >= 2) {
                $num_blocks = abs($securityLevel);
                if ($num_blocks > 4) {
                    $num_blocks = 4;
                }
                $blocks = explode(':', $ip);
                for ($i = 0; $i < $num_blocks; $i++ ) {
                    $fingerprint .= $blocks[$i] . ':';
                }
            }
        } else {
            icms_core_Debug::message('ERROR (Session Fingerprint): Invalid IP format,
                IP must be a valid IPv4 or IPv6 format', false);
            $fingerprint = '';
            return $fingerprint;
        }
        return hash('sha256', $fingerprint);
    }

    /**
     * Read a session from the database
     *
     * @param string &sess_id ID of the session
     * @return string Session data
     */
    private function readSession($sess_id) {
        $sql = sprintf('SELECT sess_data, sess_ip FROM %s WHERE sess_id = %s', icms::$xoopsDB->prefix('session'), icms::$xoopsDB->quoteString($sess_id));
        if (false != $result = icms::$xoopsDB->query($sql)) {
            if (list($sess_data, $sess_ip) = icms::$xoopsDB->fetchRow($result)) {
                if ($this->ipv6securityLevel > 1 && icms_core_DataFilter::checkVar($sess_ip, 'ip', 'ipv6')) {
                    /**
                     * also cover IPv6 localhost string
                     */
                    if ($_SERVER['REMOTE_ADDR'] == "::1") {
                        $pos = 3;
                    } else {
                        $pos = strpos($sess_ip, ":", $this->ipv6securityLevel - 1);
                    }

                    if (strncmp($sess_ip, $_SERVER['REMOTE_ADDR'], $pos)) {
                        $sess_data = '';
                    }
                } elseif ($this->securityLevel > 1 && icms_core_DataFilter::checkVar($sess_ip, 'ip', 'ipv4')) {
                    $pos = strpos($sess_ip, ".", $this->securityLevel - 1);

                    if (strncmp($sess_ip, $_SERVER['REMOTE_ADDR'], $pos)) {
                        $sess_data = '';
                    }
                }
                return $sess_data;
            }
        }
        return '';
    }

    /**
     * Inserts a session into the database
     *
     * @param string $sess_id
     * @param string $sess_data
     * @return bool
     */
    private function writeSession($sess_id, $sess_data) {
        $sess_id = icms::$xoopsDB->quoteString($sess_id);
        $sess_data = icms::$xoopsDB->quoteString($sess_data);

        $sql = sprintf("UPDATE %s SET sess_updated = '%u', sess_data = %s WHERE sess_id = %s", icms::$xoopsDB->prefix('session'), time(), $sess_data, $sess_id);
        icms::$xoopsDB->queryF($sql);
        if (!icms::$xoopsDB->getAffectedRows()) {
            $sql = sprintf("INSERT INTO %s (sess_id, sess_updated, sess_ip, sess_data)" . " VALUES (%s, '%u', %s, %s)",
                icms::$xoopsDB->prefix('session'), $sess_id, time(), icms::$xoopsDB->quoteString($_SERVER['REMOTE_ADDR']), $sess_data);
            return icms::$xoopsDB->queryF($sql);
        }
        return true;
    }

    /**
     * Destroy a session stored in DB
     *
     * @param string $sess_id
     * @return bool
     */
    private function destroySession($sess_id) {
        $sql = sprintf('DELETE FROM %s WHERE sess_id = %s', icms::$xoopsDB->prefix('session'), icms::$xoopsDB->quoteString($sess_id));
        if (!$result = icms::$xoopsDB->queryF($sql)) {
            return false;
        }
        return true;
    }

    /**
     * Garbage Collector
     *
     * @param int $expire Time in seconds until a session expires
     * @return bool
     */
    private function gcSession($expire) {
        if (empty($expire)) {
            return true;
        }
        $mintime = time() - (int) $expire;
        $sql = sprintf("DELETE FROM %s WHERE sess_updated < '%u'", icms::$xoopsDB->prefix('session'), $mintime);
        return icms::$xoopsDB->queryF($sql);
    }
}