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Developer Documentation
- Bug fixes for general core bugs in 4.0.x will end 8 May 2023 (12 months).
- Bug fixes for security issues in 4.0.x will end 13 November 2023 (18 months).
- PHP version: minimum PHP 7.3.0 Note: the minimum PHP version has increased since Moodle 3.10. PHP 7.4.x is also supported.
/lib/classes/session/ -> manager.php (source)
Differences Between: [Versions 310 and 400] [Versions 311 and 400] [Versions 39 and 400] [Versions 400 and 401] [Versions 400 and 402] [Versions 400 and 403]
1 <?php 2 // This file is part of Moodle - http://moodle.org/ 3 // 4 // Moodle is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // Moodle is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU General Public License for more details. 13 // 14 // You should have received a copy of the GNU General Public License 15 // along with Moodle. If not, see <http://www.gnu.org/licenses/>. 16 17 /** 18 * Session manager class. 19 * 20 * @package core 21 * @copyright 2013 Petr Skoda {@link http://skodak.org} 22 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 23 */ 24 25 namespace core\session; 26 27 defined('MOODLE_INTERNAL') || die(); 28 29 use html_writer; 30 31 /** 32 * Session manager, this is the public Moodle API for sessions. 33 * 34 * Following PHP functions MUST NOT be used directly: 35 * - session_start() - not necessary, lib/setup.php starts session automatically, 36 * use define('NO_MOODLE_COOKIE', true) if session not necessary. 37 * - session_write_close() - use \core\session\manager::write_close() instead. 38 * - session_destroy() - use require_logout() instead. 39 * 40 * @package core 41 * @copyright 2013 Petr Skoda {@link http://skodak.org} 42 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 43 */ 44 class manager { 45 /** @var int A hard cutoff of maximum stored history */ 46 const MAXIMUM_STORED_SESSION_HISTORY = 50; 47 48 /** @var int The recent session locks array is reset if there is a time gap more than this value in seconds */ 49 const SESSION_RESET_GAP_THRESHOLD = 1; 50 51 /** @var handler $handler active session handler instance */ 52 protected static $handler; 53 54 /** @var bool $sessionactive Is the session active? */ 55 protected static $sessionactive = null; 56 57 /** @var string $logintokenkey Key used to get and store request protection for login form. */ 58 protected static $logintokenkey = 'core_auth_login'; 59 60 /** @var array Stores the the SESSION before a request is performed, used to check incorrect read-only modes */ 61 private static $priorsession = []; 62 63 /** 64 * @var bool Used to trigger the SESSION mutation warning without actually preventing SESSION mutation. 65 * This variable is used to "copy" what the $requireslock parameter does in start_session(). 66 * Once requireslock is set in start_session it's later accessible via $handler->requires_write_lock, 67 * When using $CFG->enable_read_only_sessions_debug mode, this variable serves the same purpose without 68 * actually setting the handler as requiring a write lock. 69 */ 70 private static $requireslockdebug; 71 72 /** 73 * If the current session is not writeable, abort it, and re-open it 74 * requesting (and blocking) until a write lock is acquired. 75 * If current session was already opened with an intentional write lock, 76 * this call will not do anything. 77 * NOTE: Even when using a session handler that does not support non-locking sessions, 78 * if the original session was not opened with the explicit intention of being locked, 79 * this will still restart your session so that code behaviour matches as closely 80 * as practical across environments. 81 * 82 * @param bool $readonlysession Used by debugging logic to determine if whatever 83 * triggered the restart (e.g., a webservice) declared 84 * itself as read only. 85 */ 86 public static function restart_with_write_lock(bool $readonlysession) { 87 global $CFG; 88 89 self::$requireslockdebug = !$readonlysession; 90 91 if (self::$sessionactive && !self::$handler->requires_write_lock()) { 92 @self::$handler->abort(); 93 self::$sessionactive = false; 94 self::start_session(true); 95 } 96 } 97 98 /** 99 * Start user session. 100 * 101 * Note: This is intended to be called only from lib/setup.php! 102 */ 103 public static function start() { 104 global $CFG, $DB, $PERF; 105 106 if (isset(self::$sessionactive)) { 107 debugging('Session was already started!', DEBUG_DEVELOPER); 108 return; 109 } 110 111 // Grab the time before session lock starts. 112 $PERF->sessionlock['start'] = microtime(true); 113 self::load_handler(); 114 115 // Init the session handler only if everything initialised properly in lib/setup.php file 116 // and the session is actually required. 117 if (empty($DB) or empty($CFG->version) or !defined('NO_MOODLE_COOKIES') or NO_MOODLE_COOKIES or CLI_SCRIPT) { 118 self::$sessionactive = false; 119 self::init_empty_session(); 120 return; 121 } 122 123 if (defined('READ_ONLY_SESSION') && !empty($CFG->enable_read_only_sessions)) { 124 $requireslock = !READ_ONLY_SESSION; 125 } else { 126 $requireslock = true; // For backwards compatibility, we default to assuming that a lock is needed. 127 } 128 129 // By default make the two variables the same. This means that when they are 130 // checked below in start_session and write_close there is no possibility for 131 // the debug version to "accidentally" execute the debug mode. 132 self::$requireslockdebug = $requireslock; 133 if (defined('READ_ONLY_SESSION') && !empty($CFG->enable_read_only_sessions_debug)) { 134 // Only change the debug variable if READ_ONLY_SESSION is declared, 135 // as would happen with the real requireslock variable. 136 self::$requireslockdebug = !READ_ONLY_SESSION; 137 } 138 139 self::start_session($requireslock); 140 } 141 142 /** 143 * Handles starting a session. 144 * 145 * @param bool $requireslock If this is false then no write lock will be acquired, 146 * and the session will be read-only. 147 */ 148 private static function start_session(bool $requireslock) { 149 global $PERF, $CFG; 150 151 try { 152 self::$handler->init(); 153 self::$handler->set_requires_write_lock($requireslock); 154 self::prepare_cookies(); 155 $isnewsession = empty($_COOKIE[session_name()]); 156 157 if (!self::$handler->start()) { 158 // Could not successfully start/recover session. 159 throw new \core\session\exception(get_string('servererror')); 160 } 161 162 // Grab the time when session lock starts. 163 $PERF->sessionlock['gained'] = microtime(true); 164 $PERF->sessionlock['wait'] = $PERF->sessionlock['gained'] - $PERF->sessionlock['start']; 165 self::initialise_user_session($isnewsession); 166 self::$sessionactive = true; // Set here, so the session can be cleared if the security check fails. 167 self::check_security(); 168 169 if (!$requireslock || !self::$requireslockdebug) { 170 self::$priorsession = (array) $_SESSION['SESSION']; 171 } 172 173 if (!empty($CFG->enable_read_only_sessions) && isset($_SESSION['SESSION']->cachestore_session)) { 174 $caches = join(', ', array_keys($_SESSION['SESSION']->cachestore_session)); 175 $caches = str_replace('default_session-', '', $caches); 176 throw new \moodle_exception("The session caches can not be in the session store when " 177 . "enable_read_only_sessions is enabled. Please map all session mode caches to be outside of the " 178 . "default session store before enabling this features. Found these definitions in the session: $caches"); 179 } 180 181 // Link global $USER and $SESSION, 182 // this is tricky because PHP does not allow references to references 183 // and global keyword uses internally once reference to the $GLOBALS array. 184 // The solution is to use the $GLOBALS['USER'] and $GLOBALS['$SESSION'] 185 // as the main storage of data and put references to $_SESSION. 186 $GLOBALS['USER'] = $_SESSION['USER']; 187 $_SESSION['USER'] =& $GLOBALS['USER']; 188 $GLOBALS['SESSION'] = $_SESSION['SESSION']; 189 $_SESSION['SESSION'] =& $GLOBALS['SESSION']; 190 191 } catch (\Exception $ex) { 192 self::init_empty_session(); 193 self::$sessionactive = false; 194 throw $ex; 195 } 196 } 197 198 /** 199 * Returns current page performance info. 200 * 201 * @return array perf info 202 */ 203 public static function get_performance_info() { 204 global $CFG, $PERF; 205 206 if (!session_id()) { 207 return array(); 208 } 209 210 self::load_handler(); 211 $size = display_size(strlen(session_encode())); 212 $handler = get_class(self::$handler); 213 214 $info = array(); 215 $info['size'] = $size; 216 $info['html'] = html_writer::div("Session ($handler): $size", "sessionsize"); 217 $info['txt'] = "Session ($handler): $size "; 218 219 if (!empty($CFG->debugsessionlock)) { 220 $sessionlock = self::get_session_lock_info(); 221 if (!empty($sessionlock['held'])) { 222 // The page displays the footer and the session has been closed. 223 $sessionlocktext = "Session lock held: ".number_format($sessionlock['held'], 3)." secs"; 224 } else { 225 // The session hasn't yet been closed and so we assume now with microtime. 226 $sessionlockheld = microtime(true) - $PERF->sessionlock['gained']; 227 $sessionlocktext = "Session lock open: ".number_format($sessionlockheld, 3)." secs"; 228 } 229 $info['txt'] .= $sessionlocktext; 230 $info['html'] .= html_writer::div($sessionlocktext, "sessionlockstart"); 231 $sessionlockwaittext = "Session lock wait: ".number_format($sessionlock['wait'], 3)." secs"; 232 $info['txt'] .= $sessionlockwaittext; 233 $info['html'] .= html_writer::div($sessionlockwaittext, "sessionlockwait"); 234 } 235 236 return $info; 237 } 238 239 /** 240 * Get fully qualified name of session handler class. 241 * 242 * @return string The name of the handler class 243 */ 244 public static function get_handler_class() { 245 global $CFG, $DB; 246 247 if (PHPUNIT_TEST) { 248 return '\core\session\file'; 249 } else if (!empty($CFG->session_handler_class)) { 250 return $CFG->session_handler_class; 251 } else if (!empty($CFG->dbsessions) and $DB->session_lock_supported()) { 252 return '\core\session\database'; 253 } 254 255 return '\core\session\file'; 256 } 257 258 /** 259 * Create handler instance. 260 */ 261 protected static function load_handler() { 262 if (self::$handler) { 263 return; 264 } 265 266 // Find out which handler to use. 267 $class = self::get_handler_class(); 268 self::$handler = new $class(); 269 } 270 271 /** 272 * Empty current session, fill it with not-logged-in user info. 273 * 274 * This is intended for installation scripts, unit tests and other 275 * special areas. Do NOT use for logout and session termination 276 * in normal requests! 277 * 278 * @param mixed $newsid only used after initialising a user session, is this a new user session? 279 */ 280 public static function init_empty_session(?bool $newsid = null) { 281 global $CFG; 282 283 if (isset($GLOBALS['SESSION']->notifications)) { 284 // Backup notifications. These should be preserved across session changes until the user fetches and clears them. 285 $notifications = $GLOBALS['SESSION']->notifications; 286 } 287 $GLOBALS['SESSION'] = new \stdClass(); 288 if (isset($newsid)) { 289 $GLOBALS['SESSION']->isnewsessioncookie = $newsid; 290 } 291 292 $GLOBALS['USER'] = new \stdClass(); 293 $GLOBALS['USER']->id = 0; 294 295 if (!empty($notifications)) { 296 // Restore notifications. 297 $GLOBALS['SESSION']->notifications = $notifications; 298 } 299 if (isset($CFG->mnet_localhost_id)) { 300 $GLOBALS['USER']->mnethostid = $CFG->mnet_localhost_id; 301 } else { 302 // Not installed yet, the future host id will be most probably 1. 303 $GLOBALS['USER']->mnethostid = 1; 304 } 305 306 // Link global $USER and $SESSION. 307 $_SESSION = array(); 308 $_SESSION['USER'] =& $GLOBALS['USER']; 309 $_SESSION['SESSION'] =& $GLOBALS['SESSION']; 310 } 311 312 /** 313 * Make sure all cookie and session related stuff is configured properly before session start. 314 */ 315 protected static function prepare_cookies() { 316 global $CFG; 317 318 $cookiesecure = is_moodle_cookie_secure(); 319 320 if (!isset($CFG->cookiehttponly)) { 321 $CFG->cookiehttponly = 0; 322 } 323 324 // Set sessioncookie variable if it isn't already. 325 if (!isset($CFG->sessioncookie)) { 326 $CFG->sessioncookie = ''; 327 } 328 $sessionname = 'MoodleSession'.$CFG->sessioncookie; 329 330 // Make sure cookie domain makes sense for this wwwroot. 331 if (!isset($CFG->sessioncookiedomain)) { 332 $CFG->sessioncookiedomain = ''; 333 } else if ($CFG->sessioncookiedomain !== '') { 334 $host = parse_url($CFG->wwwroot, PHP_URL_HOST); 335 if ($CFG->sessioncookiedomain !== $host) { 336 if (substr($CFG->sessioncookiedomain, 0, 1) === '.') { 337 if (!preg_match('|^.*'.preg_quote($CFG->sessioncookiedomain, '|').'$|', $host)) { 338 // Invalid domain - it must be end part of host. 339 $CFG->sessioncookiedomain = ''; 340 } 341 } else { 342 if (!preg_match('|^.*\.'.preg_quote($CFG->sessioncookiedomain, '|').'$|', $host)) { 343 // Invalid domain - it must be end part of host. 344 $CFG->sessioncookiedomain = ''; 345 } 346 } 347 } 348 } 349 350 // Make sure the cookiepath is valid for this wwwroot or autodetect if not specified. 351 if (!isset($CFG->sessioncookiepath)) { 352 $CFG->sessioncookiepath = ''; 353 } 354 if ($CFG->sessioncookiepath !== '/') { 355 $path = parse_url($CFG->wwwroot, PHP_URL_PATH).'/'; 356 if ($CFG->sessioncookiepath === '') { 357 $CFG->sessioncookiepath = $path; 358 } else { 359 if (strpos($path, $CFG->sessioncookiepath) !== 0 or substr($CFG->sessioncookiepath, -1) !== '/') { 360 $CFG->sessioncookiepath = $path; 361 } 362 } 363 } 364 365 // Discard session ID from POST, GET and globals to tighten security, 366 // this is session fixation prevention. 367 unset($GLOBALS[$sessionname]); 368 unset($_GET[$sessionname]); 369 unset($_POST[$sessionname]); 370 unset($_REQUEST[$sessionname]); 371 372 // Compatibility hack for non-browser access to our web interface. 373 if (!empty($_COOKIE[$sessionname]) && $_COOKIE[$sessionname] == "deleted") { 374 unset($_COOKIE[$sessionname]); 375 } 376 377 // Set configuration. 378 session_name($sessionname); 379 380 $sessionoptions = [ 381 'lifetime' => 0, 382 'path' => $CFG->sessioncookiepath, 383 'domain' => $CFG->sessioncookiedomain, 384 'secure' => $cookiesecure, 385 'httponly' => $CFG->cookiehttponly, 386 ]; 387 388 if (self::should_use_samesite_none()) { 389 // If $samesite is empty, we don't want there to be any SameSite attribute. 390 $sessionoptions['samesite'] = 'None'; 391 } 392 393 session_set_cookie_params($sessionoptions); 394 395 ini_set('session.use_trans_sid', '0'); 396 ini_set('session.use_only_cookies', '1'); 397 ini_set('session.use_strict_mode', '0'); // We have custom protection in session init. 398 ini_set('session.serialize_handler', 'php'); // We can move to 'php_serialize' after we require PHP 5.5.4 form Moodle. 399 400 // Moodle does normal session timeouts, this is for leftovers only. 401 ini_set('session.gc_probability', 1); 402 ini_set('session.gc_divisor', 1000); 403 ini_set('session.gc_maxlifetime', 60*60*24*4); 404 } 405 406 /** 407 * Initialise $_SESSION, handles google access 408 * and sets up not-logged-in user properly. 409 * 410 * WARNING: $USER and $SESSION are set up later, do not use them yet! 411 * 412 * @param bool $newsid is this a new session in first http request? 413 */ 414 protected static function initialise_user_session($newsid) { 415 global $CFG, $DB; 416 417 $sid = session_id(); 418 if (!$sid) { 419 // No session, very weird. 420 error_log('Missing session ID, session not started!'); 421 self::init_empty_session($newsid); 422 return; 423 } 424 425 if (!$record = $DB->get_record('sessions', array('sid'=>$sid), 'id, sid, state, userid, lastip, timecreated, timemodified')) { 426 if (!$newsid) { 427 if (!empty($_SESSION['USER']->id)) { 428 // This should not happen, just log it, we MUST not produce any output here! 429 error_log("Cannot find session record $sid for user ".$_SESSION['USER']->id.", creating new session."); 430 } 431 // Prevent session fixation attacks. 432 session_regenerate_id(true); 433 } 434 $_SESSION = array(); 435 } 436 unset($sid); 437 438 if (isset($_SESSION['USER']->id)) { 439 if (!empty($_SESSION['USER']->realuser)) { 440 $userid = $_SESSION['USER']->realuser; 441 } else { 442 $userid = $_SESSION['USER']->id; 443 } 444 445 // Verify timeout first. 446 $maxlifetime = $CFG->sessiontimeout; 447 $timeout = false; 448 if (isguestuser($userid) or empty($userid)) { 449 // Ignore guest and not-logged in timeouts, there is very little risk here. 450 $timeout = false; 451 452 } else if ($record->timemodified < time() - $maxlifetime) { 453 $timeout = true; 454 $authsequence = get_enabled_auth_plugins(); // Auths, in sequence. 455 foreach ($authsequence as $authname) { 456 $authplugin = get_auth_plugin($authname); 457 if ($authplugin->ignore_timeout_hook($_SESSION['USER'], $record->sid, $record->timecreated, $record->timemodified)) { 458 $timeout = false; 459 break; 460 } 461 } 462 } 463 464 if ($timeout) { 465 if (defined('NO_SESSION_UPDATE') && NO_SESSION_UPDATE) { 466 return; 467 } 468 session_regenerate_id(true); 469 $_SESSION = array(); 470 $DB->delete_records('sessions', array('id'=>$record->id)); 471 472 } else { 473 // Update session tracking record. 474 475 $update = new \stdClass(); 476 $updated = false; 477 478 if ($record->userid != $userid) { 479 $update->userid = $record->userid = $userid; 480 $updated = true; 481 } 482 483 $ip = getremoteaddr(); 484 if ($record->lastip != $ip) { 485 $update->lastip = $record->lastip = $ip; 486 $updated = true; 487 } 488 489 $updatefreq = empty($CFG->session_update_timemodified_frequency) ? 20 : $CFG->session_update_timemodified_frequency; 490 491 if ($record->timemodified == $record->timecreated) { 492 // Always do first update of existing record. 493 $update->timemodified = $record->timemodified = time(); 494 $updated = true; 495 496 } else if ($record->timemodified < time() - $updatefreq) { 497 // Update the session modified flag only once every 20 seconds. 498 $update->timemodified = $record->timemodified = time(); 499 $updated = true; 500 } 501 502 if ($updated && (!defined('NO_SESSION_UPDATE') || !NO_SESSION_UPDATE)) { 503 $update->id = $record->id; 504 $DB->update_record('sessions', $update); 505 } 506 507 return; 508 } 509 } else { 510 if ($record) { 511 // This happens when people switch session handlers... 512 session_regenerate_id(true); 513 $_SESSION = array(); 514 $DB->delete_records('sessions', array('id'=>$record->id)); 515 } 516 } 517 unset($record); 518 519 $timedout = false; 520 if (!isset($_SESSION['SESSION'])) { 521 $_SESSION['SESSION'] = new \stdClass(); 522 if (!$newsid) { 523 $timedout = true; 524 } 525 } 526 527 $user = null; 528 529 if (!empty($CFG->opentowebcrawlers)) { 530 if (\core_useragent::is_web_crawler()) { 531 $user = guest_user(); 532 } 533 $referer = get_local_referer(false); 534 if (!empty($CFG->guestloginbutton) and !$user and !empty($referer)) { 535 // Automatically log in users coming from search engine results. 536 if (strpos($referer, 'google') !== false ) { 537 $user = guest_user(); 538 } else if (strpos($referer, 'altavista') !== false ) { 539 $user = guest_user(); 540 } 541 } 542 } 543 544 // Setup $USER and insert the session tracking record. 545 if ($user) { 546 self::set_user($user); 547 self::add_session_record($user->id); 548 } else { 549 self::init_empty_session($newsid); 550 self::add_session_record(0); 551 } 552 553 if ($timedout) { 554 $_SESSION['SESSION']->has_timed_out = true; 555 } 556 } 557 558 /** 559 * Insert new empty session record. 560 * @param int $userid 561 * @return \stdClass the new record 562 */ 563 protected static function add_session_record($userid) { 564 global $DB; 565 $record = new \stdClass(); 566 $record->state = 0; 567 $record->sid = session_id(); 568 $record->sessdata = null; 569 $record->userid = $userid; 570 $record->timecreated = $record->timemodified = time(); 571 $record->firstip = $record->lastip = getremoteaddr(); 572 573 $record->id = $DB->insert_record('sessions', $record); 574 575 return $record; 576 } 577 578 /** 579 * Do various session security checks. 580 * 581 * WARNING: $USER and $SESSION are set up later, do not use them yet! 582 * @throws \core\session\exception 583 */ 584 protected static function check_security() { 585 global $CFG; 586 587 if (!empty($_SESSION['USER']->id) and !empty($CFG->tracksessionip)) { 588 // Make sure current IP matches the one for this session. 589 $remoteaddr = getremoteaddr(); 590 591 if (empty($_SESSION['USER']->sessionip)) { 592 $_SESSION['USER']->sessionip = $remoteaddr; 593 } 594 595 if ($_SESSION['USER']->sessionip != $remoteaddr) { 596 // This is a security feature - terminate the session in case of any doubt. 597 self::terminate_current(); 598 throw new exception('sessionipnomatch2', 'error'); 599 } 600 } 601 } 602 603 /** 604 * Login user, to be called from complete_user_login() only. 605 * @param \stdClass $user 606 */ 607 public static function login_user(\stdClass $user) { 608 global $DB; 609 610 // Regenerate session id and delete old session, 611 // this helps prevent session fixation attacks from the same domain. 612 613 $sid = session_id(); 614 session_regenerate_id(true); 615 $DB->delete_records('sessions', array('sid'=>$sid)); 616 self::add_session_record($user->id); 617 618 // Let enrol plugins deal with new enrolments if necessary. 619 enrol_check_plugins($user); 620 621 // Setup $USER object. 622 self::set_user($user); 623 } 624 625 /** 626 * Returns a valid setting for the SameSite cookie attribute. 627 * 628 * @return string The desired setting for the SameSite attribute on the cookie. Empty string indicates the SameSite attribute 629 * should not be set at all. 630 */ 631 private static function should_use_samesite_none(): bool { 632 // We only want None or no attribute at this point. When we have cookie handling compatible with Lax, 633 // we can look at checking a setting. 634 635 // Browser support for none is not consistent yet. There are known issues with Safari, and IE11. 636 // Things are stablising, however as they're not stable yet we will deal specifically with the version of chrome 637 // that introduces a default of lax, setting it to none for the current version of chrome (2 releases before the change). 638 // We also check you are using secure cookies and HTTPS because if you are not running over HTTPS 639 // then setting SameSite=None will cause your session cookie to be rejected. 640 if (\core_useragent::is_chrome() && \core_useragent::check_chrome_version('78') && is_moodle_cookie_secure()) { 641 return true; 642 } 643 return false; 644 } 645 646 /** 647 * Terminate current user session. 648 * @return void 649 */ 650 public static function terminate_current() { 651 global $DB; 652 653 if (!self::$sessionactive) { 654 self::init_empty_session(); 655 self::$sessionactive = false; 656 return; 657 } 658 659 try { 660 $DB->delete_records('external_tokens', array('sid'=>session_id(), 'tokentype'=>EXTERNAL_TOKEN_EMBEDDED)); 661 } catch (\Exception $ignored) { 662 // Probably install/upgrade - ignore this problem. 663 } 664 665 // Initialize variable to pass-by-reference to headers_sent(&$file, &$line). 666 $file = null; 667 $line = null; 668 if (headers_sent($file, $line)) { 669 error_log('Cannot terminate session properly - headers were already sent in file: '.$file.' on line '.$line); 670 } 671 672 // Write new empty session and make sure the old one is deleted. 673 $sid = session_id(); 674 session_regenerate_id(true); 675 $DB->delete_records('sessions', array('sid'=>$sid)); 676 self::init_empty_session(); 677 self::add_session_record($_SESSION['USER']->id); // Do not use $USER here because it may not be set up yet. 678 self::write_close(); 679 } 680 681 /** 682 * No more changes in session expected. 683 * Unblocks the sessions, other scripts may start executing in parallel. 684 */ 685 public static function write_close() { 686 global $PERF, $ME, $CFG; 687 688 if (self::$sessionactive) { 689 // Grab the time when session lock is released. 690 $PERF->sessionlock['released'] = microtime(true); 691 if (!empty($PERF->sessionlock['gained'])) { 692 $PERF->sessionlock['held'] = $PERF->sessionlock['released'] - $PERF->sessionlock['gained']; 693 } 694 $PERF->sessionlock['url'] = me(); 695 self::update_recent_session_locks($PERF->sessionlock); 696 self::sessionlock_debugging(); 697 698 $requireslock = self::$handler->requires_write_lock(); 699 if (!$requireslock || !self::$requireslockdebug) { 700 // Compare the array of the earlier session data with the array now, if 701 // there is a difference then a lock is required. 702 $arraydiff = self::array_session_diff( 703 self::$priorsession, 704 (array) $_SESSION['SESSION'] 705 ); 706 707 if ($arraydiff) { 708 $error = "Script $ME defined READ_ONLY_SESSION but the following SESSION attributes were changed:"; 709 foreach ($arraydiff as $key => $value) { 710 $error .= ' $SESSION->' . $key; 711 } 712 // This will emit an error if debugging is on, even if $CFG->enable_read_only_sessions 713 // is not true as we need to surface this class of errors. 714 error_log($error); // phpcs:ignore 715 } 716 } 717 } 718 719 // More control over whether session data 720 // is persisted or not. 721 if (self::$sessionactive && session_id()) { 722 // Write session and release lock only if 723 // indication session start was clean. 724 self::$handler->write_close(); 725 } else { 726 // Otherwise, if possible lock exists want 727 // to clear it, but do not write session. 728 // If the $handler has not been set then 729 // there is no session to abort. 730 if (isset(self::$handler)) { 731 @self::$handler->abort(); 732 } 733 } 734 735 self::$sessionactive = false; 736 } 737 738 /** 739 * Does the PHP session with given id exist? 740 * 741 * The session must exist both in session table and actual 742 * session backend and the session must not be timed out. 743 * 744 * Timeout evaluation is simplified, the auth hooks are not executed. 745 * 746 * @param string $sid 747 * @return bool 748 */ 749 public static function session_exists($sid) { 750 global $DB, $CFG; 751 752 if (empty($CFG->version)) { 753 // Not installed yet, do not try to access database. 754 return false; 755 } 756 757 // Note: add sessions->state checking here if it gets implemented. 758 if (!$record = $DB->get_record('sessions', array('sid' => $sid), 'id, userid, timemodified')) { 759 return false; 760 } 761 762 if (empty($record->userid) or isguestuser($record->userid)) { 763 // Ignore guest and not-logged-in timeouts, there is very little risk here. 764 } else if ($record->timemodified < time() - $CFG->sessiontimeout) { 765 return false; 766 } 767 768 // There is no need the existence of handler storage in public API. 769 self::load_handler(); 770 return self::$handler->session_exists($sid); 771 } 772 773 /** 774 * Return the number of seconds remaining in the current session. 775 * @param string $sid 776 */ 777 public static function time_remaining($sid) { 778 global $DB, $CFG; 779 780 if (empty($CFG->version)) { 781 // Not installed yet, do not try to access database. 782 return ['userid' => 0, 'timeremaining' => $CFG->sessiontimeout]; 783 } 784 785 // Note: add sessions->state checking here if it gets implemented. 786 if (!$record = $DB->get_record('sessions', array('sid' => $sid), 'id, userid, timemodified')) { 787 return ['userid' => 0, 'timeremaining' => $CFG->sessiontimeout]; 788 } 789 790 if (empty($record->userid) or isguestuser($record->userid)) { 791 // Ignore guest and not-logged-in timeouts, there is very little risk here. 792 return ['userid' => 0, 'timeremaining' => $CFG->sessiontimeout]; 793 } else { 794 return ['userid' => $record->userid, 'timeremaining' => $CFG->sessiontimeout - (time() - $record->timemodified)]; 795 } 796 } 797 798 /** 799 * Fake last access for given session, this prevents session timeout. 800 * @param string $sid 801 */ 802 public static function touch_session($sid) { 803 global $DB; 804 805 // Timeouts depend on core sessions table only, no need to update anything in external stores. 806 807 $sql = "UPDATE {sessions} SET timemodified = :now WHERE sid = :sid"; 808 $DB->execute($sql, array('now'=>time(), 'sid'=>$sid)); 809 } 810 811 /** 812 * Terminate all sessions unconditionally. 813 */ 814 public static function kill_all_sessions() { 815 global $DB; 816 817 self::terminate_current(); 818 819 self::load_handler(); 820 self::$handler->kill_all_sessions(); 821 822 try { 823 $DB->delete_records('sessions'); 824 } catch (\dml_exception $ignored) { 825 // Do not show any warnings - might be during upgrade/installation. 826 } 827 } 828 829 /** 830 * Terminate give session unconditionally. 831 * @param string $sid 832 */ 833 public static function kill_session($sid) { 834 global $DB; 835 836 self::load_handler(); 837 838 if ($sid === session_id()) { 839 self::write_close(); 840 } 841 842 self::$handler->kill_session($sid); 843 844 $DB->delete_records('sessions', array('sid'=>$sid)); 845 } 846 847 /** 848 * Terminate all sessions of given user unconditionally. 849 * @param int $userid 850 * @param string $keepsid keep this sid if present 851 */ 852 public static function kill_user_sessions($userid, $keepsid = null) { 853 global $DB; 854 855 $sessions = $DB->get_records('sessions', array('userid'=>$userid), 'id DESC', 'id, sid'); 856 foreach ($sessions as $session) { 857 if ($keepsid and $keepsid === $session->sid) { 858 continue; 859 } 860 self::kill_session($session->sid); 861 } 862 } 863 864 /** 865 * Terminate other sessions of current user depending 866 * on $CFG->limitconcurrentlogins restriction. 867 * 868 * This is expected to be called right after complete_user_login(). 869 * 870 * NOTE: 871 * * Do not use from SSO auth plugins, this would not work. 872 * * Do not use from web services because they do not have sessions. 873 * 874 * @param int $userid 875 * @param string $sid session id to be always keep, usually the current one 876 * @return void 877 */ 878 public static function apply_concurrent_login_limit($userid, $sid = null) { 879 global $CFG, $DB; 880 881 // NOTE: the $sid parameter is here mainly to allow testing, 882 // in most cases it should be current session id. 883 884 if (isguestuser($userid) or empty($userid)) { 885 // This applies to real users only! 886 return; 887 } 888 889 if (empty($CFG->limitconcurrentlogins) or $CFG->limitconcurrentlogins < 0) { 890 return; 891 } 892 893 $count = $DB->count_records('sessions', array('userid' => $userid)); 894 895 if ($count <= $CFG->limitconcurrentlogins) { 896 return; 897 } 898 899 $i = 0; 900 $select = "userid = :userid"; 901 $params = array('userid' => $userid); 902 if ($sid) { 903 if ($DB->record_exists('sessions', array('sid' => $sid, 'userid' => $userid))) { 904 $select .= " AND sid <> :sid"; 905 $params['sid'] = $sid; 906 $i = 1; 907 } 908 } 909 910 $sessions = $DB->get_records_select('sessions', $select, $params, 'timecreated DESC', 'id, sid'); 911 foreach ($sessions as $session) { 912 $i++; 913 if ($i <= $CFG->limitconcurrentlogins) { 914 continue; 915 } 916 self::kill_session($session->sid); 917 } 918 } 919 920 /** 921 * Set current user. 922 * 923 * @param \stdClass $user record 924 */ 925 public static function set_user(\stdClass $user) { 926 global $ADMIN; 927 $GLOBALS['USER'] = $user; 928 unset($GLOBALS['USER']->description); // Conserve memory. 929 unset($GLOBALS['USER']->password); // Improve security. 930 if (isset($GLOBALS['USER']->lang)) { 931 // Make sure it is a valid lang pack name. 932 $GLOBALS['USER']->lang = clean_param($GLOBALS['USER']->lang, PARAM_LANG); 933 } 934 935 // Relink session with global $USER just in case it got unlinked somehow. 936 $_SESSION['USER'] =& $GLOBALS['USER']; 937 938 // Nullify the $ADMIN tree global. If we're changing users, then this is now stale and must be generated again if needed. 939 $ADMIN = null; 940 941 // Init session key. 942 sesskey(); 943 944 // Make sure the user is correct in web server access logs. 945 set_access_log_user(); 946 } 947 948 /** 949 * Periodic timed-out session cleanup. 950 */ 951 public static function gc() { 952 global $CFG, $DB; 953 954 // This may take a long time... 955 \core_php_time_limit::raise(); 956 957 $maxlifetime = $CFG->sessiontimeout; 958 959 try { 960 // Kill all sessions of deleted and suspended users without any hesitation. 961 $rs = $DB->get_recordset_select('sessions', "userid IN (SELECT id FROM {user} WHERE deleted <> 0 OR suspended <> 0)", array(), 'id DESC', 'id, sid'); 962 foreach ($rs as $session) { 963 self::kill_session($session->sid); 964 } 965 $rs->close(); 966 967 // Kill sessions of users with disabled plugins. 968 $authsequence = get_enabled_auth_plugins(); 969 $authsequence = array_flip($authsequence); 970 unset($authsequence['nologin']); // No login means user cannot login. 971 $authsequence = array_flip($authsequence); 972 973 list($notplugins, $params) = $DB->get_in_or_equal($authsequence, SQL_PARAMS_QM, '', false); 974 $rs = $DB->get_recordset_select('sessions', "userid IN (SELECT id FROM {user} WHERE auth $notplugins)", $params, 'id DESC', 'id, sid'); 975 foreach ($rs as $session) { 976 self::kill_session($session->sid); 977 } 978 $rs->close(); 979 980 // Now get a list of time-out candidates - real users only. 981 $sql = "SELECT u.*, s.sid, s.timecreated AS s_timecreated, s.timemodified AS s_timemodified 982 FROM {user} u 983 JOIN {sessions} s ON s.userid = u.id 984 WHERE s.timemodified < :purgebefore AND u.id <> :guestid"; 985 $params = array('purgebefore' => (time() - $maxlifetime), 'guestid'=>$CFG->siteguest); 986 987 $authplugins = array(); 988 foreach ($authsequence as $authname) { 989 $authplugins[$authname] = get_auth_plugin($authname); 990 } 991 $rs = $DB->get_recordset_sql($sql, $params); 992 foreach ($rs as $user) { 993 foreach ($authplugins as $authplugin) { 994 /** @var \auth_plugin_base $authplugin*/ 995 if ($authplugin->ignore_timeout_hook($user, $user->sid, $user->s_timecreated, $user->s_timemodified)) { 996 continue 2; 997 } 998 } 999 self::kill_session($user->sid); 1000 } 1001 $rs->close(); 1002 1003 // Delete expired sessions for guest user account, give them larger timeout, there is no security risk here. 1004 $params = array('purgebefore' => (time() - ($maxlifetime * 5)), 'guestid'=>$CFG->siteguest); 1005 $rs = $DB->get_recordset_select('sessions', 'userid = :guestid AND timemodified < :purgebefore', $params, 'id DESC', 'id, sid'); 1006 foreach ($rs as $session) { 1007 self::kill_session($session->sid); 1008 } 1009 $rs->close(); 1010 1011 // Delete expired sessions for userid = 0 (not logged in), better kill them asap to release memory. 1012 $params = array('purgebefore' => (time() - $maxlifetime)); 1013 $rs = $DB->get_recordset_select('sessions', 'userid = 0 AND timemodified < :purgebefore', $params, 'id DESC', 'id, sid'); 1014 foreach ($rs as $session) { 1015 self::kill_session($session->sid); 1016 } 1017 $rs->close(); 1018 1019 // Cleanup letfovers from the first browser access because it may set multiple cookies and then use only one. 1020 $params = array('purgebefore' => (time() - 60*3)); 1021 $rs = $DB->get_recordset_select('sessions', 'userid = 0 AND timemodified = timecreated AND timemodified < :purgebefore', $params, 'id ASC', 'id, sid'); 1022 foreach ($rs as $session) { 1023 self::kill_session($session->sid); 1024 } 1025 $rs->close(); 1026 1027 } catch (\Exception $ex) { 1028 debugging('Error gc-ing sessions: '.$ex->getMessage(), DEBUG_NORMAL, $ex->getTrace()); 1029 } 1030 } 1031 1032 /** 1033 * Is current $USER logged-in-as somebody else? 1034 * @return bool 1035 */ 1036 public static function is_loggedinas() { 1037 return !empty($GLOBALS['USER']->realuser); 1038 } 1039 1040 /** 1041 * Returns the $USER object ignoring current login-as session 1042 * @return \stdClass user object 1043 */ 1044 public static function get_realuser() { 1045 if (self::is_loggedinas()) { 1046 return $_SESSION['REALUSER']; 1047 } else { 1048 return $GLOBALS['USER']; 1049 } 1050 } 1051 1052 /** 1053 * Login as another user - no security checks here. 1054 * @param int $userid 1055 * @param \context $context 1056 * @param bool $generateevent Set to false to prevent the loginas event to be generated 1057 * @return void 1058 */ 1059 public static function loginas($userid, \context $context, $generateevent = true) { 1060 global $USER; 1061 1062 if (self::is_loggedinas()) { 1063 return; 1064 } 1065 1066 // Switch to fresh new $_SESSION. 1067 $_SESSION = array(); 1068 $_SESSION['REALSESSION'] = clone($GLOBALS['SESSION']); 1069 $GLOBALS['SESSION'] = new \stdClass(); 1070 $_SESSION['SESSION'] =& $GLOBALS['SESSION']; 1071 1072 // Create the new $USER object with all details and reload needed capabilities. 1073 $_SESSION['REALUSER'] = clone($GLOBALS['USER']); 1074 $user = get_complete_user_data('id', $userid); 1075 $user->realuser = $_SESSION['REALUSER']->id; 1076 $user->loginascontext = $context; 1077 1078 // Let enrol plugins deal with new enrolments if necessary. 1079 enrol_check_plugins($user); 1080 1081 if ($generateevent) { 1082 // Create event before $USER is updated. 1083 $event = \core\event\user_loggedinas::create( 1084 array( 1085 'objectid' => $USER->id, 1086 'context' => $context, 1087 'relateduserid' => $userid, 1088 'other' => array( 1089 'originalusername' => fullname($USER, true), 1090 'loggedinasusername' => fullname($user, true) 1091 ) 1092 ) 1093 ); 1094 } 1095 1096 // Set up global $USER. 1097 \core\session\manager::set_user($user); 1098 1099 if ($generateevent) { 1100 $event->trigger(); 1101 } 1102 1103 // Queue migrating the messaging data, if we need to. 1104 if (!get_user_preferences('core_message_migrate_data', false, $userid)) { 1105 // Check if there are any legacy messages to migrate. 1106 if (\core_message\helper::legacy_messages_exist($userid)) { 1107 \core_message\task\migrate_message_data::queue_task($userid); 1108 } else { 1109 set_user_preference('core_message_migrate_data', true, $userid); 1110 } 1111 } 1112 } 1113 1114 /** 1115 * Add a JS session keepalive to the page. 1116 * 1117 * A JS session keepalive script will be called to update the session modification time every $frequency seconds. 1118 * 1119 * Upon failure, the specified error message will be shown to the user. 1120 * 1121 * @param string $identifier The string identifier for the message to show on failure. 1122 * @param string $component The string component for the message to show on failure. 1123 * @param int $frequency The update frequency in seconds. 1124 * @param int $timeout The timeout of each request in seconds. 1125 * @throws coding_exception IF the frequency is longer than the session lifetime. 1126 */ 1127 public static function keepalive($identifier = 'sessionerroruser', $component = 'error', $frequency = null, $timeout = 0) { 1128 global $CFG, $PAGE; 1129 1130 if ($frequency) { 1131 if ($frequency > $CFG->sessiontimeout) { 1132 // Sanity check the frequency. 1133 throw new \coding_exception('Keepalive frequency is longer than the session lifespan.'); 1134 } 1135 } else { 1136 // A frequency of sessiontimeout / 10 matches the timeouts in core/network amd module. 1137 $frequency = $CFG->sessiontimeout / 10; 1138 } 1139 1140 $PAGE->requires->js_call_amd('core/network', 'keepalive', array( 1141 $frequency, 1142 $timeout, 1143 $identifier, 1144 $component 1145 )); 1146 } 1147 1148 /** 1149 * Generate a new login token and store it in the session. 1150 * 1151 * @return array The current login state. 1152 */ 1153 private static function create_login_token() { 1154 global $SESSION; 1155 1156 $state = [ 1157 'token' => random_string(32), 1158 'created' => time() // Server time - not user time. 1159 ]; 1160 1161 if (!isset($SESSION->logintoken)) { 1162 $SESSION->logintoken = []; 1163 } 1164 1165 // Overwrite any previous values. 1166 $SESSION->logintoken[self::$logintokenkey] = $state; 1167 1168 return $state; 1169 } 1170 1171 /** 1172 * Get the current login token or generate a new one. 1173 * 1174 * All login forms generated from Moodle must include a login token 1175 * named "logintoken" with the value being the result of this function. 1176 * Logins will be rejected if they do not include this token as well as 1177 * the username and password fields. 1178 * 1179 * @return string The current login token. 1180 */ 1181 public static function get_login_token() { 1182 global $CFG, $SESSION; 1183 1184 $state = false; 1185 1186 if (!isset($SESSION->logintoken)) { 1187 $SESSION->logintoken = []; 1188 } 1189 1190 if (array_key_exists(self::$logintokenkey, $SESSION->logintoken)) { 1191 $state = $SESSION->logintoken[self::$logintokenkey]; 1192 } 1193 if (empty($state)) { 1194 $state = self::create_login_token(); 1195 } 1196 1197 // Check token lifespan. 1198 if ($state['created'] < (time() - $CFG->sessiontimeout)) { 1199 $state = self::create_login_token(); 1200 } 1201 1202 // Return the current session login token. 1203 if (array_key_exists('token', $state)) { 1204 return $state['token']; 1205 } else { 1206 return false; 1207 } 1208 } 1209 1210 /** 1211 * Check the submitted value against the stored login token. 1212 * 1213 * @param mixed $token The value submitted in the login form that we are validating. 1214 * If false is passed for the token, this function will always return true. 1215 * @return boolean If the submitted token is valid. 1216 */ 1217 public static function validate_login_token($token = false) { 1218 global $CFG; 1219 1220 if (!empty($CFG->alternateloginurl) || !empty($CFG->disablelogintoken)) { 1221 // An external login page cannot generate the login token we need to protect CSRF on 1222 // login requests. 1223 // Other custom login workflows may skip this check by setting disablelogintoken in config. 1224 return true; 1225 } 1226 if ($token === false) { 1227 // authenticate_user_login is a core function was extended to validate tokens. 1228 // For existing uses other than the login form it does not 1229 // validate that a token was generated. 1230 // Some uses that do not validate the token are login/token.php, 1231 // or an auth plugin like auth/ldap/auth.php. 1232 return true; 1233 } 1234 1235 $currenttoken = self::get_login_token(); 1236 1237 // We need to clean the login token so the old one is not valid again. 1238 self::create_login_token(); 1239 1240 if ($currenttoken !== $token) { 1241 // Fail the login. 1242 return false; 1243 } 1244 return true; 1245 } 1246 1247 /** 1248 * Get the recent session locks array. 1249 * 1250 * @return array Recent session locks array. 1251 */ 1252 public static function get_recent_session_locks() { 1253 global $SESSION; 1254 1255 if (!isset($SESSION->recentsessionlocks)) { 1256 // This will hold the pages that blocks other page. 1257 $SESSION->recentsessionlocks = array(); 1258 } 1259 1260 return $SESSION->recentsessionlocks; 1261 } 1262 1263 /** 1264 * Updates the recent session locks. 1265 * 1266 * This function will store session lock info of all the pages visited. 1267 * 1268 * @param array $sessionlock Session lock array. 1269 */ 1270 public static function update_recent_session_locks($sessionlock) { 1271 global $CFG, $SESSION; 1272 1273 if (empty($CFG->debugsessionlock)) { 1274 return; 1275 } 1276 1277 $readonlysession = defined('READ_ONLY_SESSION') && READ_ONLY_SESSION; 1278 $readonlydebugging = !empty($CFG->enable_read_only_sessions) || !empty($CFG->enable_read_only_sessions_debug); 1279 if ($readonlysession && $readonlydebugging) { 1280 return; 1281 } 1282 1283 $SESSION->recentsessionlocks = self::get_recent_session_locks(); 1284 array_push($SESSION->recentsessionlocks, $sessionlock); 1285 1286 self::cleanup_recent_session_locks(); 1287 } 1288 1289 /** 1290 * Reset recent session locks array if there is a time gap more than SESSION_RESET_GAP_THRESHOLD. 1291 */ 1292 public static function cleanup_recent_session_locks() { 1293 global $SESSION; 1294 1295 $locks = self::get_recent_session_locks(); 1296 1297 if (count($locks) > self::MAXIMUM_STORED_SESSION_HISTORY) { 1298 // Keep the last MAXIMUM_STORED_SESSION_HISTORY locks and ignore the rest. 1299 $locks = array_slice($locks, -1 * self::MAXIMUM_STORED_SESSION_HISTORY); 1300 } 1301 1302 if (count($locks) > 2) { 1303 for ($i = count($locks) - 1; $i > 0; $i--) { 1304 // Calculate the gap between session locks. 1305 $gap = $locks[$i]['released'] - $locks[$i - 1]['start']; 1306 if ($gap >= self::SESSION_RESET_GAP_THRESHOLD) { 1307 // Remove previous locks if the gap is 1 second or more. 1308 $SESSION->recentsessionlocks = array_slice($locks, $i); 1309 break; 1310 } 1311 } 1312 } 1313 } 1314 1315 /** 1316 * Get the page that blocks other pages at a specific timestamp. 1317 * 1318 * Look for a page whose lock was gained before that timestamp, and released after that timestamp. 1319 * 1320 * @param float $time Time before session lock starts. 1321 * @return array|null 1322 */ 1323 public static function get_locked_page_at($time) { 1324 $recentsessionlocks = self::get_recent_session_locks(); 1325 foreach ($recentsessionlocks as $recentsessionlock) { 1326 if ($time >= $recentsessionlock['gained'] && 1327 $time <= $recentsessionlock['released']) { 1328 return $recentsessionlock; 1329 } 1330 } 1331 } 1332 1333 /** 1334 * Display the page which blocks other pages. 1335 * 1336 * @return string 1337 */ 1338 public static function display_blocking_page() { 1339 global $PERF; 1340 1341 $page = self::get_locked_page_at($PERF->sessionlock['start']); 1342 $output = "Script ".me()." was blocked for "; 1343 $output .= number_format($PERF->sessionlock['wait'], 3); 1344 if ($page != null) { 1345 $output .= " second(s) by script: "; 1346 $output .= $page['url']; 1347 } else { 1348 $output .= " second(s) by an unknown script."; 1349 } 1350 1351 return $output; 1352 } 1353 1354 /** 1355 * Get session lock info of the current page. 1356 * 1357 * @return array 1358 */ 1359 public static function get_session_lock_info() { 1360 global $PERF; 1361 1362 if (!isset($PERF->sessionlock)) { 1363 return null; 1364 } 1365 return $PERF->sessionlock; 1366 } 1367 1368 /** 1369 * Display debugging info about slow and blocked script. 1370 */ 1371 public static function sessionlock_debugging() { 1372 global $CFG, $PERF; 1373 1374 if (!empty($CFG->debugsessionlock)) { 1375 if (isset($PERF->sessionlock['held']) && $PERF->sessionlock['held'] > $CFG->debugsessionlock) { 1376 debugging("Script ".me()." locked the session for ".number_format($PERF->sessionlock['held'], 3) 1377 ." seconds, it should close the session using \core\session\manager::write_close().", DEBUG_NORMAL); 1378 } 1379 1380 if (isset($PERF->sessionlock['wait']) && $PERF->sessionlock['wait'] > $CFG->debugsessionlock) { 1381 $output = self::display_blocking_page(); 1382 debugging($output, DEBUG_DEVELOPER); 1383 } 1384 } 1385 } 1386 1387 /** 1388 * Compares two arrays outputs the difference. 1389 * 1390 * Note this does not use array_diff_assoc due to 1391 * the use of stdClasses in Moodle sessions. 1392 * 1393 * @param array $array1 1394 * @param array $array2 1395 * @return array 1396 */ 1397 private static function array_session_diff(array $array1, array $array2) : array { 1398 $difference = []; 1399 foreach ($array1 as $key => $value) { 1400 if (!isset($array2[$key])) { 1401 $difference[$key] = $value; 1402 } else if ($array2[$key] !== $value) { 1403 $difference[$key] = $value; 1404 } 1405 } 1406 1407 return $difference; 1408 } 1409 }
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