You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
433 lines
15 KiB
433 lines
15 KiB
<?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/>.
|
|
|
|
/**
|
|
* Redis based session handler.
|
|
*
|
|
* @package core
|
|
* @copyright 2015 Russell Smith <mr-russ@smith2001.net>
|
|
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
|
|
*/
|
|
|
|
namespace core\session;
|
|
|
|
use RedisException;
|
|
|
|
defined('MOODLE_INTERNAL') || die();
|
|
|
|
/**
|
|
* Redis based session handler.
|
|
*
|
|
* The default Redis session handler does not handle locking in 2.2.7, so we have written a php session handler
|
|
* that uses locking. The places where locking is used was modeled from the memcached code that is used in Moodle
|
|
* https://github.com/php-memcached-dev/php-memcached/blob/master/php_memcached_session.c
|
|
*
|
|
* @package core
|
|
* @copyright 2016 Russell Smith
|
|
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
|
|
*/
|
|
class redis extends handler {
|
|
/** @var string $host save_path string */
|
|
protected $host = '';
|
|
/** @var int $port The port to connect to */
|
|
protected $port = 6379;
|
|
/** @var string $auth redis password */
|
|
protected $auth = '';
|
|
/** @var int $database the Redis database to store sesions in */
|
|
protected $database = 0;
|
|
/** @var array $servers list of servers parsed from save_path */
|
|
protected $prefix = '';
|
|
/** @var int $acquiretimeout how long to wait for session lock in seconds */
|
|
protected $acquiretimeout = 120;
|
|
/** @var int $serializer The serializer to use */
|
|
protected $serializer = \Redis::SERIALIZER_PHP;
|
|
/**
|
|
* @var int $lockexpire how long to wait in seconds before expiring the lock automatically
|
|
* so that other requests may continue execution, ignored if PECL redis is below version 2.2.0.
|
|
*/
|
|
protected $lockexpire;
|
|
|
|
/** @var Redis Connection */
|
|
protected $connection = null;
|
|
|
|
/** @var array $locks List of currently held locks by this page. */
|
|
protected $locks = array();
|
|
|
|
/** @var int $timeout How long sessions live before expiring. */
|
|
protected $timeout;
|
|
|
|
/**
|
|
* Create new instance of handler.
|
|
*/
|
|
public function __construct() {
|
|
global $CFG;
|
|
|
|
if (isset($CFG->session_redis_host)) {
|
|
$this->host = $CFG->session_redis_host;
|
|
}
|
|
|
|
if (isset($CFG->session_redis_port)) {
|
|
$this->port = (int)$CFG->session_redis_port;
|
|
}
|
|
|
|
if (isset($CFG->session_redis_auth)) {
|
|
$this->auth = $CFG->session_redis_auth;
|
|
}
|
|
|
|
if (isset($CFG->session_redis_database)) {
|
|
$this->database = (int)$CFG->session_redis_database;
|
|
}
|
|
|
|
if (isset($CFG->session_redis_prefix)) {
|
|
$this->prefix = $CFG->session_redis_prefix;
|
|
}
|
|
|
|
if (isset($CFG->session_redis_acquire_lock_timeout)) {
|
|
$this->acquiretimeout = (int)$CFG->session_redis_acquire_lock_timeout;
|
|
}
|
|
|
|
if (!empty($CFG->session_redis_serializer_use_igbinary) && defined('\Redis::SERIALIZER_IGBINARY')) {
|
|
$this->serializer = \Redis::SERIALIZER_IGBINARY; // Set igbinary serializer if phpredis supports it.
|
|
}
|
|
|
|
// The following configures the session lifetime in redis to allow some
|
|
// wriggle room in the user noticing they've been booted off and
|
|
// letting them log back in before they lose their session entirely.
|
|
$updatefreq = empty($CFG->session_update_timemodified_frequency) ? 20 : $CFG->session_update_timemodified_frequency;
|
|
$this->timeout = $CFG->sessiontimeout + $updatefreq + MINSECS;
|
|
|
|
$this->lockexpire = $CFG->sessiontimeout;
|
|
if (isset($CFG->session_redis_lock_expire)) {
|
|
$this->lockexpire = (int)$CFG->session_redis_lock_expire;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Start the session.
|
|
*
|
|
* @return bool success
|
|
*/
|
|
public function start() {
|
|
$result = parent::start();
|
|
|
|
return $result;
|
|
}
|
|
|
|
/**
|
|
* Init session handler.
|
|
*/
|
|
public function init() {
|
|
if (!extension_loaded('redis')) {
|
|
throw new exception('sessionhandlerproblem', 'error', '', null, 'redis extension is not loaded');
|
|
}
|
|
|
|
if (empty($this->host)) {
|
|
throw new exception('sessionhandlerproblem', 'error', '', null,
|
|
'$CFG->session_redis_host must be specified in config.php');
|
|
}
|
|
|
|
// The session handler requires a version of Redis with the SETEX command (at least 2.0).
|
|
$version = phpversion('Redis');
|
|
if (!$version or version_compare($version, '2.0') <= 0) {
|
|
throw new exception('sessionhandlerproblem', 'error', '', null, 'redis extension version must be at least 2.0');
|
|
}
|
|
|
|
$this->connection = new \Redis();
|
|
|
|
$result = session_set_save_handler(array($this, 'handler_open'),
|
|
array($this, 'handler_close'),
|
|
array($this, 'handler_read'),
|
|
array($this, 'handler_write'),
|
|
array($this, 'handler_destroy'),
|
|
array($this, 'handler_gc'));
|
|
if (!$result) {
|
|
throw new exception('redissessionhandlerproblem', 'error');
|
|
}
|
|
|
|
// MDL-59866: Add retries for connections (up to 5 times) to make sure it goes through.
|
|
$counter = 1;
|
|
$maxnumberofretries = 5;
|
|
|
|
while ($counter <= $maxnumberofretries) {
|
|
|
|
try {
|
|
|
|
$delay = rand(100000, 500000);
|
|
|
|
// One second timeout was chosen as it is long for connection, but short enough for a user to be patient.
|
|
if (!$this->connection->connect($this->host, $this->port, 1, null, $delay)) {
|
|
throw new RedisException('Unable to connect to host.');
|
|
}
|
|
|
|
if ($this->auth !== '') {
|
|
if (!$this->connection->auth($this->auth)) {
|
|
throw new RedisException('Unable to authenticate.');
|
|
}
|
|
}
|
|
|
|
if (!$this->connection->setOption(\Redis::OPT_SERIALIZER, $this->serializer)) {
|
|
throw new RedisException('Unable to set Redis PHP Serializer option.');
|
|
}
|
|
|
|
if ($this->prefix !== '') {
|
|
// Use custom prefix on sessions.
|
|
if (!$this->connection->setOption(\Redis::OPT_PREFIX, $this->prefix)) {
|
|
throw new RedisException('Unable to set Redis Prefix option.');
|
|
}
|
|
}
|
|
if ($this->database !== 0) {
|
|
if (!$this->connection->select($this->database)) {
|
|
throw new RedisException('Unable to select Redis database '.$this->database.'.');
|
|
}
|
|
}
|
|
$this->connection->ping();
|
|
return true;
|
|
} catch (RedisException $e) {
|
|
$logstring = "Failed to connect (try {$counter} out of {$maxnumberofretries}) to redis ";
|
|
$logstring .= "at {$this->host}:{$this->port}, error returned was: {$e->getMessage()}";
|
|
|
|
// @codingStandardsIgnoreStart
|
|
error_log($logstring);
|
|
// @codingStandardsIgnoreEnd
|
|
}
|
|
|
|
$counter++;
|
|
|
|
// Introduce a random sleep between 100ms and 500ms.
|
|
usleep(rand(100000, 500000));
|
|
}
|
|
|
|
// We have exhausted our retries, time to give up.
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Update our session search path to include session name when opened.
|
|
*
|
|
* @param string $savepath unused session save path. (ignored)
|
|
* @param string $sessionname Session name for this session. (ignored)
|
|
* @return bool true always as we will succeed.
|
|
*/
|
|
public function handler_open($savepath, $sessionname) {
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Close the session completely. We also remove all locks we may have obtained that aren't expired.
|
|
*
|
|
* @return bool true on success. false on unable to unlock sessions.
|
|
*/
|
|
public function handler_close() {
|
|
try {
|
|
foreach ($this->locks as $id => $expirytime) {
|
|
if ($expirytime > $this->time()) {
|
|
$this->unlock_session($id);
|
|
}
|
|
unset($this->locks[$id]);
|
|
}
|
|
} catch (RedisException $e) {
|
|
error_log('Failed talking to redis: '.$e->getMessage());
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
/**
|
|
* Read the session data from storage
|
|
*
|
|
* @param string $id The session id to read from storage.
|
|
* @return string The session data for PHP to process.
|
|
*
|
|
* @throws RedisException when we are unable to talk to the Redis server.
|
|
*/
|
|
public function handler_read($id) {
|
|
try {
|
|
$this->lock_session($id);
|
|
$sessiondata = $this->connection->get($id);
|
|
if ($sessiondata === false) {
|
|
$this->unlock_session($id);
|
|
return '';
|
|
}
|
|
$this->connection->expire($id, $this->timeout);
|
|
} catch (RedisException $e) {
|
|
error_log('Failed talking to redis: '.$e->getMessage());
|
|
throw $e;
|
|
}
|
|
return $sessiondata;
|
|
}
|
|
|
|
/**
|
|
* Write the serialized session data to our session store.
|
|
*
|
|
* @param string $id session id to write.
|
|
* @param string $data session data
|
|
* @return bool true on write success, false on failure
|
|
*/
|
|
public function handler_write($id, $data) {
|
|
if (is_null($this->connection)) {
|
|
// The session has already been closed, don't attempt another write.
|
|
error_log('Tried to write session: '.$id.' before open or after close.');
|
|
return false;
|
|
}
|
|
|
|
// We do not do locking here because memcached doesn't. Also
|
|
// PHP does open, read, destroy, write, close. When a session doesn't exist.
|
|
// There can be race conditions on new sessions racing each other but we can
|
|
// address that in the future.
|
|
try {
|
|
$this->connection->setex($id, $this->timeout, $data);
|
|
} catch (RedisException $e) {
|
|
error_log('Failed talking to redis: '.$e->getMessage());
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Handle destroying a session.
|
|
*
|
|
* @param string $id the session id to destroy.
|
|
* @return bool true if the session was deleted, false otherwise.
|
|
*/
|
|
public function handler_destroy($id) {
|
|
try {
|
|
$this->connection->del($id);
|
|
$this->unlock_session($id);
|
|
} catch (RedisException $e) {
|
|
error_log('Failed talking to redis: '.$e->getMessage());
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Garbage collect sessions. We don't we any as Redis does it for us.
|
|
*
|
|
* @param integer $maxlifetime All sessions older than this should be removed.
|
|
* @return bool true, as Redis handles expiry for us.
|
|
*/
|
|
public function handler_gc($maxlifetime) {
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Unlock a session.
|
|
*
|
|
* @param string $id Session id to be unlocked.
|
|
*/
|
|
protected function unlock_session($id) {
|
|
if (isset($this->locks[$id])) {
|
|
$this->connection->del($id.".lock");
|
|
unset($this->locks[$id]);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Obtain a session lock so we are the only one using it at the moent.
|
|
*
|
|
* @param string $id The session id to lock.
|
|
* @return bool true when session was locked, exception otherwise.
|
|
* @throws exception When we are unable to obtain a session lock.
|
|
*/
|
|
protected function lock_session($id) {
|
|
$lockkey = $id.".lock";
|
|
|
|
$haslock = isset($this->locks[$id]) && $this->time() < $this->locks[$id];
|
|
$startlocktime = $this->time();
|
|
|
|
/* To be able to ensure sessions don't write out of order we must obtain an exclusive lock
|
|
* on the session for the entire time it is open. If another AJAX call, or page is using
|
|
* the session then we just wait until it finishes before we can open the session.
|
|
*/
|
|
while (!$haslock) {
|
|
$haslock = $this->connection->setnx($lockkey, '1');
|
|
if (!$haslock) {
|
|
usleep(rand(100000, 1000000));
|
|
if ($this->time() > $startlocktime + $this->acquiretimeout) {
|
|
// This is a fatal error, better inform users.
|
|
// It should not happen very often - all pages that need long time to execute
|
|
// should close session immediately after access control checks.
|
|
error_log('Cannot obtain session lock for sid: '.$id.' within '.$this->acquiretimeout.
|
|
'. It is likely another page has a long session lock, or the session lock was never released.');
|
|
throw new exception("Unable to obtain session lock");
|
|
}
|
|
} else {
|
|
$this->locks[$id] = $this->time() + $this->lockexpire;
|
|
$this->connection->expire($lockkey, $this->lockexpire);
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Return the current time.
|
|
*
|
|
* @return int the current time as a unixtimestamp.
|
|
*/
|
|
protected function time() {
|
|
return time();
|
|
}
|
|
|
|
/**
|
|
* Check the backend contains data for this session id.
|
|
*
|
|
* Note: this is intended to be called from manager::session_exists() only.
|
|
*
|
|
* @param string $sid
|
|
* @return bool true if session found.
|
|
*/
|
|
public function session_exists($sid) {
|
|
if (!$this->connection) {
|
|
return false;
|
|
}
|
|
|
|
try {
|
|
return !empty($this->connection->exists($sid));
|
|
} catch (RedisException $e) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Kill all active sessions, the core sessions table is purged afterwards.
|
|
*/
|
|
public function kill_all_sessions() {
|
|
global $DB;
|
|
if (!$this->connection) {
|
|
return;
|
|
}
|
|
|
|
$rs = $DB->get_recordset('sessions', array(), 'id DESC', 'id, sid');
|
|
foreach ($rs as $record) {
|
|
$this->handler_destroy($record->sid);
|
|
}
|
|
$rs->close();
|
|
}
|
|
|
|
/**
|
|
* Kill one session, the session record is removed afterwards.
|
|
*
|
|
* @param string $sid
|
|
*/
|
|
public function kill_session($sid) {
|
|
if (!$this->connection) {
|
|
return;
|
|
}
|
|
|
|
$this->handler_destroy($sid);
|
|
}
|
|
}
|
|
|