File: /home/iestorre/moodleAW/moodle02/lib/classes/session/manager.php
<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Session manager class.
*
* @package core
* @copyright 2013 Petr Skoda {@link http://skodak.org}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core\session;
defined('MOODLE_INTERNAL') || die();
/**
* Session manager, this is the public Moodle API for sessions.
*
* Following PHP functions MUST NOT be used directly:
* - session_start() - not necessary, lib/setup.php starts session automatically,
* use define('NO_MOODLE_COOKIE', true) if session not necessary.
* - session_write_close() - use \core\session\manager::write_close() instead.
* - session_destroy() - use require_logout() instead.
*
* @package core
* @copyright 2013 Petr Skoda {@link http://skodak.org}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class manager {
/** @var handler $handler active session handler instance */
protected static $handler;
/** @var bool $sessionactive Is the session active? */
protected static $sessionactive = null;
/**
* Start user session.
*
* Note: This is intended to be called only from lib/setup.php!
*/
public static function start() {
global $CFG, $DB;
if (isset(self::$sessionactive)) {
debugging('Session was already started!', DEBUG_DEVELOPER);
return;
}
self::load_handler();
// Init the session handler only if everything initialised properly in lib/setup.php file
// and the session is actually required.
if (empty($DB) or empty($CFG->version) or !defined('NO_MOODLE_COOKIES') or NO_MOODLE_COOKIES or CLI_SCRIPT) {
self::$sessionactive = false;
self::init_empty_session();
return;
}
try {
self::$handler->init();
self::prepare_cookies();
$newsid = empty($_COOKIE[session_name()]);
self::$handler->start();
self::initialise_user_session($newsid);
self::check_security();
// Link global $USER and $SESSION,
// this is tricky because PHP does not allow references to references
// and global keyword uses internally once reference to the $GLOBALS array.
// The solution is to use the $GLOBALS['USER'] and $GLOBALS['$SESSION']
// as the main storage of data and put references to $_SESSION.
$GLOBALS['USER'] = $_SESSION['USER'];
$_SESSION['USER'] =& $GLOBALS['USER'];
$GLOBALS['SESSION'] = $_SESSION['SESSION'];
$_SESSION['SESSION'] =& $GLOBALS['SESSION'];
} catch (\Exception $ex) {
@session_write_close();
self::init_empty_session();
self::$sessionactive = false;
throw $ex;
}
self::$sessionactive = true;
}
/**
* Returns current page performance info.
*
* @return array perf info
*/
public static function get_performance_info() {
if (!session_id()) {
return array();
}
self::load_handler();
$size = display_size(strlen(session_encode()));
$handler = get_class(self::$handler);
$info = array();
$info['size'] = $size;
$info['html'] = "<span class=\"sessionsize\">Session ($handler): $size</span> ";
$info['txt'] = "Session ($handler): $size ";
return $info;
}
/**
* Create handler instance.
*/
protected static function load_handler() {
global $CFG, $DB;
if (self::$handler) {
return;
}
// Find out which handler to use.
if (PHPUNIT_TEST) {
$class = '\core\session\file';
} else if (!empty($CFG->session_handler_class)) {
$class = $CFG->session_handler_class;
} else if (!empty($CFG->dbsessions) and $DB->session_lock_supported()) {
$class = '\core\session\database';
} else {
$class = '\core\session\file';
}
self::$handler = new $class();
}
/**
* Empty current session, fill it with not-logged-in user info.
*
* This is intended for installation scripts, unit tests and other
* special areas. Do NOT use for logout and session termination
* in normal requests!
*/
public static function init_empty_session() {
global $CFG;
$GLOBALS['SESSION'] = new \stdClass();
$GLOBALS['USER'] = new \stdClass();
$GLOBALS['USER']->id = 0;
if (isset($CFG->mnet_localhost_id)) {
$GLOBALS['USER']->mnethostid = $CFG->mnet_localhost_id;
} else {
// Not installed yet, the future host id will be most probably 1.
$GLOBALS['USER']->mnethostid = 1;
}
// Link global $USER and $SESSION.
$_SESSION = array();
$_SESSION['USER'] =& $GLOBALS['USER'];
$_SESSION['SESSION'] =& $GLOBALS['SESSION'];
}
/**
* Make sure all cookie and session related stuff is configured properly before session start.
*/
protected static function prepare_cookies() {
global $CFG;
if (!isset($CFG->cookiesecure) or (strpos($CFG->wwwroot, 'https://') !== 0 and empty($CFG->sslproxy))) {
$CFG->cookiesecure = 0;
}
if (!isset($CFG->cookiehttponly)) {
$CFG->cookiehttponly = 0;
}
// Set sessioncookie variable if it isn't already.
if (!isset($CFG->sessioncookie)) {
$CFG->sessioncookie = '';
}
$sessionname = 'MoodleSession'.$CFG->sessioncookie;
// Make sure cookie domain makes sense for this wwwroot.
if (!isset($CFG->sessioncookiedomain)) {
$CFG->sessioncookiedomain = '';
} else if ($CFG->sessioncookiedomain !== '') {
$host = parse_url($CFG->wwwroot, PHP_URL_HOST);
if ($CFG->sessioncookiedomain !== $host) {
if (substr($CFG->sessioncookiedomain, 0, 1) === '.') {
if (!preg_match('|^.*'.preg_quote($CFG->sessioncookiedomain, '|').'$|', $host)) {
// Invalid domain - it must be end part of host.
$CFG->sessioncookiedomain = '';
}
} else {
if (!preg_match('|^.*\.'.preg_quote($CFG->sessioncookiedomain, '|').'$|', $host)) {
// Invalid domain - it must be end part of host.
$CFG->sessioncookiedomain = '';
}
}
}
}
// Make sure the cookiepath is valid for this wwwroot or autodetect if not specified.
if (!isset($CFG->sessioncookiepath)) {
$CFG->sessioncookiepath = '';
}
if ($CFG->sessioncookiepath !== '/') {
$path = parse_url($CFG->wwwroot, PHP_URL_PATH).'/';
if ($CFG->sessioncookiepath === '') {
$CFG->sessioncookiepath = $path;
} else {
if (strpos($path, $CFG->sessioncookiepath) !== 0 or substr($CFG->sessioncookiepath, -1) !== '/') {
$CFG->sessioncookiepath = $path;
}
}
}
// Discard session ID from POST, GET and globals to tighten security,
// this is session fixation prevention.
unset($GLOBALS[$sessionname]);
unset($_GET[$sessionname]);
unset($_POST[$sessionname]);
unset($_REQUEST[$sessionname]);
// Compatibility hack for non-browser access to our web interface.
if (!empty($_COOKIE[$sessionname]) && $_COOKIE[$sessionname] == "deleted") {
unset($_COOKIE[$sessionname]);
}
// Set configuration.
session_name($sessionname);
session_set_cookie_params(0, $CFG->sessioncookiepath, $CFG->sessioncookiedomain, $CFG->cookiesecure, $CFG->cookiehttponly);
ini_set('session.use_trans_sid', '0');
ini_set('session.use_only_cookies', '1');
ini_set('session.hash_function', '0'); // For now MD5 - we do not have room for sha-1 in sessions table.
ini_set('session.use_strict_mode', '0'); // We have custom protection in session init.
ini_set('session.serialize_handler', 'php'); // We can move to 'php_serialize' after we require PHP 5.5.4 form Moodle.
// Moodle does normal session timeouts, this is for leftovers only.
ini_set('session.gc_probability', 1);
ini_set('session.gc_divisor', 1000);
ini_set('session.gc_maxlifetime', 60*60*24*4);
}
/**
* Initialise $_SESSION, handles google access
* and sets up not-logged-in user properly.
*
* WARNING: $USER and $SESSION are set up later, do not use them yet!
*
* @param bool $newsid is this a new session in first http request?
*/
protected static function initialise_user_session($newsid) {
global $CFG, $DB;
$sid = session_id();
if (!$sid) {
// No session, very weird.
error_log('Missing session ID, session not started!');
self::init_empty_session();
return;
}
if (!$record = $DB->get_record('sessions', array('sid'=>$sid), 'id, sid, state, userid, lastip, timecreated, timemodified')) {
if (!$newsid) {
if (!empty($_SESSION['USER']->id)) {
// This should not happen, just log it, we MUST not produce any output here!
error_log("Cannot find session record $sid for user ".$_SESSION['USER']->id.", creating new session.");
}
// Prevent session fixation attacks.
session_regenerate_id(true);
}
$_SESSION = array();
}
unset($sid);
if (isset($_SESSION['USER']->id)) {
if (!empty($_SESSION['USER']->realuser)) {
$userid = $_SESSION['USER']->realuser;
} else {
$userid = $_SESSION['USER']->id;
}
// Verify timeout first.
$maxlifetime = $CFG->sessiontimeout;
$timeout = false;
if (isguestuser($userid) or empty($userid)) {
// Ignore guest and not-logged in timeouts, there is very little risk here.
$timeout = false;
} else if ($record->timemodified < time() - $maxlifetime) {
$timeout = true;
$authsequence = get_enabled_auth_plugins(); // Auths, in sequence.
foreach ($authsequence as $authname) {
$authplugin = get_auth_plugin($authname);
if ($authplugin->ignore_timeout_hook($_SESSION['USER'], $record->sid, $record->timecreated, $record->timemodified)) {
$timeout = false;
break;
}
}
}
if ($timeout) {
session_regenerate_id(true);
$_SESSION = array();
$DB->delete_records('sessions', array('id'=>$record->id));
} else {
// Update session tracking record.
$update = new \stdClass();
$updated = false;
if ($record->userid != $userid) {
$update->userid = $record->userid = $userid;
$updated = true;
}
$ip = getremoteaddr();
if ($record->lastip != $ip) {
$update->lastip = $record->lastip = $ip;
$updated = true;
}
$updatefreq = empty($CFG->session_update_timemodified_frequency) ? 20 : $CFG->session_update_timemodified_frequency;
if ($record->timemodified == $record->timecreated) {
// Always do first update of existing record.
$update->timemodified = $record->timemodified = time();
$updated = true;
} else if ($record->timemodified < time() - $updatefreq) {
// Update the session modified flag only once every 20 seconds.
$update->timemodified = $record->timemodified = time();
$updated = true;
}
if ($updated) {
$update->id = $record->id;
$DB->update_record('sessions', $update);
}
return;
}
} else {
if ($record) {
// This happens when people switch session handlers...
session_regenerate_id(true);
$_SESSION = array();
$DB->delete_records('sessions', array('id'=>$record->id));
}
}
unset($record);
$timedout = false;
if (!isset($_SESSION['SESSION'])) {
$_SESSION['SESSION'] = new \stdClass();
if (!$newsid) {
$timedout = true;
}
}
$user = null;
if (!empty($CFG->opentogoogle)) {
if (is_web_crawler()) {
$user = guest_user();
}
if (!empty($CFG->guestloginbutton) and !$user and !empty($_SERVER['HTTP_REFERER'])) {
// Automatically log in users coming from search engine results.
if (strpos($_SERVER['HTTP_REFERER'], 'google') !== false ) {
$user = guest_user();
} else if (strpos($_SERVER['HTTP_REFERER'], 'altavista') !== false ) {
$user = guest_user();
}
}
}
// Setup $USER and insert the session tracking record.
if ($user) {
self::set_user($user);
self::add_session_record($user->id);
} else {
self::init_empty_session();
self::add_session_record(0);
}
if ($timedout) {
$_SESSION['SESSION']->has_timed_out = true;
}
}
/**
* Insert new empty session record.
* @param int $userid
* @return \stdClass the new record
*/
protected static function add_session_record($userid) {
global $DB;
$record = new \stdClass();
$record->state = 0;
$record->sid = session_id();
$record->sessdata = null;
$record->userid = $userid;
$record->timecreated = $record->timemodified = time();
$record->firstip = $record->lastip = getremoteaddr();
$record->id = $DB->insert_record('sessions', $record);
return $record;
}
/**
* Do various session security checks.
*
* WARNING: $USER and $SESSION are set up later, do not use them yet!
*/
protected static function check_security() {
global $CFG;
if (!empty($_SESSION['USER']->id) and !empty($CFG->tracksessionip)) {
// Make sure current IP matches the one for this session.
$remoteaddr = getremoteaddr();
if (empty($_SESSION['USER']->sessionip)) {
$_SESSION['USER']->sessionip = $remoteaddr;
}
if ($_SESSION['USER']->sessionip != $remoteaddr) {
// This is a security feature - terminate the session in case of any doubt.
self::terminate_current();
throw new exception('sessionipnomatch2', 'error');
}
}
}
/**
* Login user, to be called from complete_user_login() only.
* @param \stdClass $user
*/
public static function login_user(\stdClass $user) {
global $DB;
// Regenerate session id and delete old session,
// this helps prevent session fixation attacks from the same domain.
$sid = session_id();
session_regenerate_id(true);
$DB->delete_records('sessions', array('sid'=>$sid));
self::add_session_record($user->id);
// Let enrol plugins deal with new enrolments if necessary.
enrol_check_plugins($user);
// Setup $USER object.
self::set_user($user);
}
/**
* Terminate current user session.
* @return void
*/
public static function terminate_current() {
global $DB;
if (!self::$sessionactive) {
self::init_empty_session();
self::$sessionactive = false;
return;
}
try {
$DB->delete_records('external_tokens', array('sid'=>session_id(), 'tokentype'=>EXTERNAL_TOKEN_EMBEDDED));
} catch (\Exception $ignored) {
// Probably install/upgrade - ignore this problem.
}
// Initialize variable to pass-by-reference to headers_sent(&$file, &$line).
$file = null;
$line = null;
if (headers_sent($file, $line)) {
error_log('Cannot terminate session properly - headers were already sent in file: '.$file.' on line '.$line);
}
// Write new empty session and make sure the old one is deleted.
$sid = session_id();
session_regenerate_id(true);
$DB->delete_records('sessions', array('sid'=>$sid));
self::init_empty_session();
self::add_session_record($_SESSION['USER']->id); // Do not use $USER here because it may not be set up yet.
session_write_close();
self::$sessionactive = false;
}
/**
* No more changes in session expected.
* Unblocks the sessions, other scripts may start executing in parallel.
*/
public static function write_close() {
if (self::$sessionactive) {
session_write_close();
} else {
if (session_id()) {
@session_write_close();
}
}
self::$sessionactive = false;
}
/**
* Does the PHP session with given id exist?
*
* Note: this does not actually verify the presence of sessions record.
*
* @param string $sid
* @return bool
*/
public static function session_exists($sid) {
self::load_handler();
return self::$handler->session_exists($sid);
}
/**
* Fake last access for given session, this prevents session timeout.
* @param string $sid
*/
public static function touch_session($sid) {
global $DB;
// Timeouts depend on core sessions table only, no need to update anything in external stores.
$sql = "UPDATE {sessions} SET timemodified = :now WHERE sid = :sid";
$DB->execute($sql, array('now'=>time(), 'sid'=>$sid));
}
/**
* Terminate all sessions unconditionally.
*/
public static function kill_all_sessions() {
global $DB;
self::terminate_current();
self::load_handler();
self::$handler->kill_all_sessions();
try {
$DB->delete_records('sessions');
} catch (\dml_exception $ignored) {
// Do not show any warnings - might be during upgrade/installation.
}
}
/**
* Terminate give session unconditionally.
* @param string $sid
*/
public static function kill_session($sid) {
global $DB;
self::load_handler();
if ($sid === session_id()) {
self::write_close();
}
self::$handler->kill_session($sid);
$DB->delete_records('sessions', array('sid'=>$sid));
}
/**
* Terminate all sessions of given user unconditionally.
* @param int $userid
*/
public static function kill_user_sessions($userid) {
global $DB;
$sessions = $DB->get_records('sessions', array('userid'=>$userid), 'id DESC', 'id, sid');
foreach ($sessions as $session) {
self::kill_session($session->sid);
}
}
/**
* Set current user.
*
* @param \stdClass $user record
*/
public static function set_user(\stdClass $user) {
$GLOBALS['USER'] = $user;
unset($GLOBALS['USER']->description); // Conserve memory.
unset($GLOBALS['USER']->password); // Improve security.
if (isset($GLOBALS['USER']->lang)) {
// Make sure it is a valid lang pack name.
$GLOBALS['USER']->lang = clean_param($GLOBALS['USER']->lang, PARAM_LANG);
}
// Relink session with global $USER just in case it got unlinked somehow.
$_SESSION['USER'] =& $GLOBALS['USER'];
// Init session key.
sesskey();
}
/**
* Periodic timed-out session cleanup.
*/
public static function gc() {
global $CFG, $DB;
// This may take a long time...
set_time_limit(0);
$maxlifetime = $CFG->sessiontimeout;
try {
// Kill all sessions of deleted and suspended users without any hesitation.
$rs = $DB->get_recordset_select('sessions', "userid IN (SELECT id FROM {user} WHERE deleted <> 0 OR suspended <> 0)", array(), 'id DESC', 'id, sid');
foreach ($rs as $session) {
self::kill_session($session->sid);
}
$rs->close();
// Kill sessions of users with disabled plugins.
$auth_sequence = get_enabled_auth_plugins(true);
$auth_sequence = array_flip($auth_sequence);
unset($auth_sequence['nologin']); // No login means user cannot login.
$auth_sequence = array_flip($auth_sequence);
list($notplugins, $params) = $DB->get_in_or_equal($auth_sequence, SQL_PARAMS_QM, '', false);
$rs = $DB->get_recordset_select('sessions', "userid IN (SELECT id FROM {user} WHERE auth $notplugins)", $params, 'id DESC', 'id, sid');
foreach ($rs as $session) {
self::kill_session($session->sid);
}
$rs->close();
// Now get a list of time-out candidates - real users only.
$sql = "SELECT u.*, s.sid, s.timecreated AS s_timecreated, s.timemodified AS s_timemodified
FROM {user} u
JOIN {sessions} s ON s.userid = u.id
WHERE s.timemodified < :purgebefore AND u.id <> :guestid";
$params = array('purgebefore' => (time() - $maxlifetime), 'guestid'=>$CFG->siteguest);
$authplugins = array();
foreach ($auth_sequence as $authname) {
$authplugins[$authname] = get_auth_plugin($authname);
}
$rs = $DB->get_recordset_sql($sql, $params);
foreach ($rs as $user) {
foreach ($authplugins as $authplugin) {
/** @var \auth_plugin_base $authplugin*/
if ($authplugin->ignore_timeout_hook($user, $user->sid, $user->s_timecreated, $user->s_timemodified)) {
continue;
}
}
self::kill_session($user->sid);
}
$rs->close();
// Delete expired sessions for guest user account, give them larger timeout, there is no security risk here.
$params = array('purgebefore' => (time() - ($maxlifetime * 5)), 'guestid'=>$CFG->siteguest);
$rs = $DB->get_recordset_select('sessions', 'userid = :guestid AND timemodified < :purgebefore', $params, 'id DESC', 'id, sid');
foreach ($rs as $session) {
self::kill_session($session->sid);
}
$rs->close();
// Delete expired sessions for userid = 0 (not logged in), better kill them asap to release memory.
$params = array('purgebefore' => (time() - $maxlifetime));
$rs = $DB->get_recordset_select('sessions', 'userid = 0 AND timemodified < :purgebefore', $params, 'id DESC', 'id, sid');
foreach ($rs as $session) {
self::kill_session($session->sid);
}
$rs->close();
// Cleanup letfovers from the first browser access because it may set multiple cookies and then use only one.
$params = array('purgebefore' => (time() - 60*3));
$rs = $DB->get_recordset_select('sessions', 'userid = 0 AND timemodified = timecreated AND timemodified < :purgebefore', $params, 'id ASC', 'id, sid');
foreach ($rs as $session) {
self::kill_session($session->sid);
}
$rs->close();
} catch (\Exception $ex) {
debugging('Error gc-ing sessions: '.$ex->getMessage(), DEBUG_NORMAL, $ex->getTrace());
}
}
/**
* Is current $USER logged-in-as somebody else?
* @return bool
*/
public static function is_loggedinas() {
return !empty($GLOBALS['USER']->realuser);
}
/**
* Returns the $USER object ignoring current login-as session
* @return \stdClass user object
*/
public static function get_realuser() {
if (self::is_loggedinas()) {
return $_SESSION['REALUSER'];
} else {
return $GLOBALS['USER'];
}
}
/**
* Login as another user - no security checks here.
* @param int $userid
* @param \context $context
* @return void
*/
public static function loginas($userid, \context $context) {
global $USER;
if (self::is_loggedinas()) {
return;
}
// Switch to fresh new $_SESSION.
$_SESSION = array();
$_SESSION['REALSESSION'] = clone($GLOBALS['SESSION']);
$GLOBALS['SESSION'] = new \stdClass();
$_SESSION['SESSION'] =& $GLOBALS['SESSION'];
// Create the new $USER object with all details and reload needed capabilities.
$_SESSION['REALUSER'] = clone($GLOBALS['USER']);
$user = get_complete_user_data('id', $userid);
$user->realuser = $_SESSION['REALUSER']->id;
$user->loginascontext = $context;
// Let enrol plugins deal with new enrolments if necessary.
enrol_check_plugins($user);
// Create event before $USER is updated.
$event = \core\event\user_loggedinas::create(
array(
'objectid' => $USER->id,
'context' => $context,
'relateduserid' => $userid,
'other' => array(
'originalusername' => fullname($USER, true),
'loggedinasusername' => fullname($user, true)
)
)
);
// Set up global $USER.
\core\session\manager::set_user($user);
$event->trigger();
}
}