includes/session/PHPSessionHandler.php

   1 <?php
   2 /**
   3  * Session storage in object cache.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Session
  22  */
  23
  24 namespace MediaWiki\Session;
  25
  26 use Psr\Log\LoggerInterface;
  27 use BagOStuff;
  28
  29 /**
  30  * Adapter for PHP's session handling
  31  * @ingroup Session
  32  * @since 1.27
  33  */
  34 class PHPSessionHandler implements \SessionHandlerInterface {
  35         /** @var PHPSessionHandler */
  36         protected static $instance = null;
  37
  38         /** @var bool Whether PHP session handling is enabled */
  39         protected $enable = false;
  40         protected $warn = true;
  41
  42         /** @var SessionManager|null */
  43         protected $manager;
  44
  45         /** @var BagOStuff|null */
  46         protected $store;
  47
  48         /** @var LoggerInterface */
  49         protected $logger;
  50
  51         /** @var array Track original session fields for later modification check */
  52         protected $sessionFieldCache = [];
  53
  54         protected function __construct( SessionManager $manager ) {
  55                 $this->setEnableFlags(
  56                         \RequestContext::getMain()->getConfig()->get( 'PHPSessionHandling' )
  57                 );
  58                 $manager->setupPHPSessionHandler( $this );
  59         }
  60
  61         /**
  62          * Set $this->enable and $this->warn
  63          *
  64          * Separate just because there doesn't seem to be a good way to test it
  65          * otherwise.
  66          *
  67          * @param string $PHPSessionHandling See $wgPHPSessionHandling
  68          */
  69         private function setEnableFlags( $PHPSessionHandling ) {
  70                 switch ( $PHPSessionHandling ) {
  71                         case 'enable':
  72                                 $this->enable = true;
  73                                 $this->warn = false;
  74                                 break;
  75
  76                         case 'warn':
  77                                 $this->enable = true;
  78                                 $this->warn = true;
  79                                 break;
  80
  81                         case 'disable':
  82                                 $this->enable = false;
  83                                 $this->warn = false;
  84                                 break;
  85                 }
  86         }
  87
  88         /**
  89          * Test whether the handler is installed
  90          * @return bool
  91          */
  92         public static function isInstalled() {
  93                 return (bool)self::$instance;
  94         }
  95
  96         /**
  97          * Test whether the handler is installed and enabled
  98          * @return bool
  99          */
 100         public static function isEnabled() {
 101                 return self::$instance && self::$instance->enable;
 102         }
 103
 104         /**
 105          * Install a session handler for the current web request
 106          * @param SessionManager $manager
 107          */
 108         public static function install( SessionManager $manager ) {
 109                 if ( self::$instance ) {
 110                         $manager->setupPHPSessionHandler( self::$instance );
 111                         return;
 112                 }
 113
 114                 self::$instance = new self( $manager );
 115
 116                 // Close any auto-started session, before we replace it
 117                 session_write_close();
 118
 119                 // Tell PHP not to mess with cookies itself
 120                 ini_set( 'session.use_cookies', 0 );
 121                 ini_set( 'session.use_trans_sid', 0 );
 122
 123                 // T124510: Disable automatic PHP session related cache headers.
 124                 // MediaWiki adds it's own headers and the default PHP behavior may
 125                 // set headers such as 'Pragma: no-cache' that cause problems with
 126                 // some user agents.
 127                 session_cache_limiter( '' );
 128
 129                 // Also set a sane serialization handler
 130                 \Wikimedia\PhpSessionSerializer::setSerializeHandler();
 131
 132                 // Register this as the save handler, and register an appropriate
 133                 // shutdown function.
 134                 session_set_save_handler( self::$instance, true );
 135         }
 136
 137         /**
 138          * Set the manager, store, and logger
 139          * @private Use self::install().
 140          * @param SessionManager $manager
 141          * @param BagOStuff $store
 142          * @param LoggerInterface $store
 143          */
 144         public function setManager(
 145                 SessionManager $manager, BagOStuff $store, LoggerInterface $logger
 146         ) {
 147                 if ( $this->manager !== $manager ) {
 148                         // Close any existing session before we change stores
 149                         if ( $this->manager ) {
 150                                 session_write_close();
 151                         }
 152                         $this->manager = $manager;
 153                         $this->store = $store;
 154                         $this->logger = $logger;
 155                         \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 156                 }
 157         }
 158
 159         /**
 160          * Initialize the session (handler)
 161          * @private For internal use only
 162          * @param string $save_path Path used to store session files (ignored)
 163          * @param string $session_name Session name (ignored)
 164          * @return bool Success
 165          */
 166         public function open( $save_path, $session_name ) {
 167                 if ( self::$instance !== $this ) {
 168                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 169                 }
 170                 if ( !$this->enable ) {
 171                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 172                 }
 173                 return true;
 174         }
 175
 176         /**
 177          * Close the session (handler)
 178          * @private For internal use only
 179          * @return bool Success
 180          */
 181         public function close() {
 182                 if ( self::$instance !== $this ) {
 183                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 184                 }
 185                 $this->sessionFieldCache = [];
 186                 return true;
 187         }
 188
 189         /**
 190          * Read session data
 191          * @private For internal use only
 192          * @param string $id Session id
 193          * @return string Session data
 194          */
 195         public function read( $id ) {
 196                 if ( self::$instance !== $this ) {
 197                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 198                 }
 199                 if ( !$this->enable ) {
 200                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 201                 }
 202
 203                 $session = $this->manager->getSessionById( $id, false );
 204                 if ( !$session ) {
 205                         return '';
 206                 }
 207                 $session->persist();
 208
 209                 $data = iterator_to_array( $session );
 210                 $this->sessionFieldCache[$id] = $data;
 211                 return (string)\Wikimedia\PhpSessionSerializer::encode( $data );
 212         }
 213
 214         /**
 215          * Write session data
 216          * @private For internal use only
 217          * @param string $id Session id
 218          * @param string $dataStr Session data. Not that you should ever call this
 219          *   directly, but note that this has the same issues with code injection
 220          *   via user-controlled data as does PHP's unserialize function.
 221          * @return bool Success
 222          */
 223         public function write( $id, $dataStr ) {
 224                 if ( self::$instance !== $this ) {
 225                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 226                 }
 227                 if ( !$this->enable ) {
 228                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 229                 }
 230
 231                 $session = $this->manager->getSessionById( $id, true );
 232                 if ( !$session ) {
 233                         // This can happen under normal circumstances, if the session exists but is
 234                         // invalid. Let's emit a log warning instead of a PHP warning.
 235                         $this->logger->warning(
 236                                 __METHOD__ . ': Session "{session}" cannot be loaded, skipping write.',
 237                                 [
 238                                         'session' => $id,
 239                         ] );
 240                         return true;
 241                 }
 242
 243                 // First, decode the string PHP handed us
 244                 $data = \Wikimedia\PhpSessionSerializer::decode( $dataStr );
 245                 if ( $data === null ) {
 246                         // @codeCoverageIgnoreStart
 247                         return false;
 248                         // @codeCoverageIgnoreEnd
 249                 }
 250
 251                 // Now merge the data into the Session object.
 252                 $changed = false;
 253                 $cache = isset( $this->sessionFieldCache[$id] ) ? $this->sessionFieldCache[$id] : [];
 254                 foreach ( $data as $key => $value ) {
 255                         if ( !array_key_exists( $key, $cache ) ) {
 256                                 if ( $session->exists( $key ) ) {
 257                                         // New in both, so ignore and log
 258                                         $this->logger->warning(
 259                                                 __METHOD__ . ": Key \"$key\" added in both Session and \$_SESSION!"
 260                                         );
 261                                 } else {
 262                                         // New in $_SESSION, keep it
 263                                         $session->set( $key, $value );
 264                                         $changed = true;
 265                                 }
 266                         } elseif ( $cache[$key] === $value ) {
 267                                 // Unchanged in $_SESSION, so ignore it
 268                         } elseif ( !$session->exists( $key ) ) {
 269                                 // Deleted in Session, keep but log
 270                                 $this->logger->warning(
 271                                         __METHOD__ . ": Key \"$key\" deleted in Session and changed in \$_SESSION!"
 272                                 );
 273                                 $session->set( $key, $value );
 274                                 $changed = true;
 275                         } elseif ( $cache[$key] === $session->get( $key ) ) {
 276                                 // Unchanged in Session, so keep it
 277                                 $session->set( $key, $value );
 278                                 $changed = true;
 279                         } else {
 280                                 // Changed in both, so ignore and log
 281                                 $this->logger->warning(
 282                                         __METHOD__ . ": Key \"$key\" changed in both Session and \$_SESSION!"
 283                                 );
 284                         }
 285                 }
 286                 // Anything deleted in $_SESSION and unchanged in Session should be deleted too
 287                 // (but not if $_SESSION can't represent it at all)
 288                 \Wikimedia\PhpSessionSerializer::setLogger( new \Psr\Log\NullLogger() );
 289                 foreach ( $cache as $key => $value ) {
 290                         if ( !array_key_exists( $key, $data ) && $session->exists( $key ) &&
 291                                 \Wikimedia\PhpSessionSerializer::encode( [ $key => true ] )
 292                         ) {
 293                                 if ( $cache[$key] === $session->get( $key ) ) {
 294                                         // Unchanged in Session, delete it
 295                                         $session->remove( $key );
 296                                         $changed = true;
 297                                 } else {
 298                                         // Changed in Session, ignore deletion and log
 299                                         $this->logger->warning(
 300                                                 __METHOD__ . ": Key \"$key\" changed in Session and deleted in \$_SESSION!"
 301                                         );
 302                                 }
 303                         }
 304                 }
 305                 \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 306
 307                 // Save and update cache if anything changed
 308                 if ( $changed ) {
 309                         if ( $this->warn ) {
 310                                 wfDeprecated( '$_SESSION', '1.27' );
 311                                 $this->logger->warning( 'Something wrote to $_SESSION!' );
 312                         }
 313
 314                         $session->save();
 315                         $this->sessionFieldCache[$id] = iterator_to_array( $session );
 316                 }
 317
 318                 $session->persist();
 319
 320                 return true;
 321         }
 322
 323         /**
 324          * Destroy a session
 325          * @private For internal use only
 326          * @param string $id Session id
 327          * @return bool Success
 328          */
 329         public function destroy( $id ) {
 330                 if ( self::$instance !== $this ) {
 331                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 332                 }
 333                 if ( !$this->enable ) {
 334                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 335                 }
 336                 $session = $this->manager->getSessionById( $id, false );
 337                 if ( $session ) {
 338                         $session->clear();
 339                 }
 340                 return true;
 341         }
 342
 343         /**
 344          * Execute garbage collection.
 345          * @private For internal use only
 346          * @param int $maxlifetime Maximum session life time (ignored)
 347          * @return bool Success
 348          */
 349         public function gc( $maxlifetime ) {
 350                 if ( self::$instance !== $this ) {
 351                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 352                 }
 353                 $before = date( 'YmdHis', time() );
 354                 $this->store->deleteObjectsExpiringBefore( $before );
 355                 return true;
 356         }
 357 }