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                 if ( defined( 'MW_NO_SESSION_HANDLER' ) ) {
 115                         throw new \BadMethodCallException( 'MW_NO_SESSION_HANDLER is defined' );
 116                 }
 117
 118                 self::$instance = new self( $manager );
 119
 120                 // Close any auto-started session, before we replace it
 121                 session_write_close();
 122
 123                 // Tell PHP not to mess with cookies itself
 124                 ini_set( 'session.use_cookies', 0 );
 125                 ini_set( 'session.use_trans_sid', 0 );
 126
 127                 // T124510: Disable automatic PHP session related cache headers.
 128                 // MediaWiki adds it's own headers and the default PHP behavior may
 129                 // set headers such as 'Pragma: no-cache' that cause problems with
 130                 // some user agents.
 131                 session_cache_limiter( '' );
 132
 133                 // Also set a sane serialization handler
 134                 \Wikimedia\PhpSessionSerializer::setSerializeHandler();
 135
 136                 // Register this as the save handler, and register an appropriate
 137                 // shutdown function.
 138                 session_set_save_handler( self::$instance, true );
 139         }
 140
 141         /**
 142          * Set the manager, store, and logger
 143          * @private Use self::install().
 144          * @param SessionManager $manager
 145          * @param BagOStuff $store
 146          * @param LoggerInterface $store
 147          */
 148         public function setManager(
 149                 SessionManager $manager, BagOStuff $store, LoggerInterface $logger
 150         ) {
 151                 if ( $this->manager !== $manager ) {
 152                         // Close any existing session before we change stores
 153                         if ( $this->manager ) {
 154                                 session_write_close();
 155                         }
 156                         $this->manager = $manager;
 157                         $this->store = $store;
 158                         $this->logger = $logger;
 159                         \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 160                 }
 161         }
 162
 163         /**
 164          * Initialize the session (handler)
 165          * @private For internal use only
 166          * @param string $save_path Path used to store session files (ignored)
 167          * @param string $session_name Session name (ignored)
 168          * @return bool Success
 169          */
 170         public function open( $save_path, $session_name ) {
 171                 if ( self::$instance !== $this ) {
 172                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 173                 }
 174                 if ( !$this->enable ) {
 175                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 176                 }
 177                 return true;
 178         }
 179
 180         /**
 181          * Close the session (handler)
 182          * @private For internal use only
 183          * @return bool Success
 184          */
 185         public function close() {
 186                 if ( self::$instance !== $this ) {
 187                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 188                 }
 189                 $this->sessionFieldCache = [];
 190                 return true;
 191         }
 192
 193         /**
 194          * Read session data
 195          * @private For internal use only
 196          * @param string $id Session id
 197          * @return string Session data
 198          */
 199         public function read( $id ) {
 200                 if ( self::$instance !== $this ) {
 201                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 202                 }
 203                 if ( !$this->enable ) {
 204                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 205                 }
 206
 207                 $session = $this->manager->getSessionById( $id, false );
 208                 if ( !$session ) {
 209                         return '';
 210                 }
 211                 $session->persist();
 212
 213                 $data = iterator_to_array( $session );
 214                 $this->sessionFieldCache[$id] = $data;
 215                 return (string)\Wikimedia\PhpSessionSerializer::encode( $data );
 216         }
 217
 218         /**
 219          * Write session data
 220          * @private For internal use only
 221          * @param string $id Session id
 222          * @param string $dataStr Session data. Not that you should ever call this
 223          *   directly, but note that this has the same issues with code injection
 224          *   via user-controlled data as does PHP's unserialize function.
 225          * @return bool Success
 226          */
 227         public function write( $id, $dataStr ) {
 228                 if ( self::$instance !== $this ) {
 229                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 230                 }
 231                 if ( !$this->enable ) {
 232                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 233                 }
 234
 235                 $session = $this->manager->getSessionById( $id, true );
 236                 if ( !$session ) {
 237                         // This can happen under normal circumstances, if the session exists but is
 238                         // invalid. Let's emit a log warning instead of a PHP warning.
 239                         $this->logger->warning(
 240                                 __METHOD__ . ': Session "{session}" cannot be loaded, skipping write.',
 241                                 [
 242                                         'session' => $id,
 243                         ] );
 244                         return true;
 245                 }
 246
 247                 // First, decode the string PHP handed us
 248                 $data = \Wikimedia\PhpSessionSerializer::decode( $dataStr );
 249                 if ( $data === null ) {
 250                         // @codeCoverageIgnoreStart
 251                         return false;
 252                         // @codeCoverageIgnoreEnd
 253                 }
 254
 255                 // Now merge the data into the Session object.
 256                 $changed = false;
 257                 $cache = isset( $this->sessionFieldCache[$id] ) ? $this->sessionFieldCache[$id] : [];
 258                 foreach ( $data as $key => $value ) {
 259                         if ( !array_key_exists( $key, $cache ) ) {
 260                                 if ( $session->exists( $key ) ) {
 261                                         // New in both, so ignore and log
 262                                         $this->logger->warning(
 263                                                 __METHOD__ . ": Key \"$key\" added in both Session and \$_SESSION!"
 264                                         );
 265                                 } else {
 266                                         // New in $_SESSION, keep it
 267                                         $session->set( $key, $value );
 268                                         $changed = true;
 269                                 }
 270                         } elseif ( $cache[$key] === $value ) {
 271                                 // Unchanged in $_SESSION, so ignore it
 272                         } elseif ( !$session->exists( $key ) ) {
 273                                 // Deleted in Session, keep but log
 274                                 $this->logger->warning(
 275                                         __METHOD__ . ": Key \"$key\" deleted in Session and changed in \$_SESSION!"
 276                                 );
 277                                 $session->set( $key, $value );
 278                                 $changed = true;
 279                         } elseif ( $cache[$key] === $session->get( $key ) ) {
 280                                 // Unchanged in Session, so keep it
 281                                 $session->set( $key, $value );
 282                                 $changed = true;
 283                         } else {
 284                                 // Changed in both, so ignore and log
 285                                 $this->logger->warning(
 286                                         __METHOD__ . ": Key \"$key\" changed in both Session and \$_SESSION!"
 287                                 );
 288                         }
 289                 }
 290                 // Anything deleted in $_SESSION and unchanged in Session should be deleted too
 291                 // (but not if $_SESSION can't represent it at all)
 292                 \Wikimedia\PhpSessionSerializer::setLogger( new \Psr\Log\NullLogger() );
 293                 foreach ( $cache as $key => $value ) {
 294                         if ( !array_key_exists( $key, $data ) && $session->exists( $key ) &&
 295                                 \Wikimedia\PhpSessionSerializer::encode( [ $key => true ] )
 296                         ) {
 297                                 if ( $cache[$key] === $session->get( $key ) ) {
 298                                         // Unchanged in Session, delete it
 299                                         $session->remove( $key );
 300                                         $changed = true;
 301                                 } else {
 302                                         // Changed in Session, ignore deletion and log
 303                                         $this->logger->warning(
 304                                                 __METHOD__ . ": Key \"$key\" changed in Session and deleted in \$_SESSION!"
 305                                         );
 306                                 }
 307                         }
 308                 }
 309                 \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 310
 311                 // Save and update cache if anything changed
 312                 if ( $changed ) {
 313                         if ( $this->warn ) {
 314                                 wfDeprecated( '$_SESSION', '1.27' );
 315                                 $this->logger->warning( 'Something wrote to $_SESSION!' );
 316                         }
 317
 318                         $session->save();
 319                         $this->sessionFieldCache[$id] = iterator_to_array( $session );
 320                 }
 321
 322                 $session->persist();
 323
 324                 return true;
 325         }
 326
 327         /**
 328          * Destroy a session
 329          * @private For internal use only
 330          * @param string $id Session id
 331          * @return bool Success
 332          */
 333         public function destroy( $id ) {
 334                 if ( self::$instance !== $this ) {
 335                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 336                 }
 337                 if ( !$this->enable ) {
 338                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 339                 }
 340                 $session = $this->manager->getSessionById( $id, false );
 341                 if ( $session ) {
 342                         $session->clear();
 343                 }
 344                 return true;
 345         }
 346
 347         /**
 348          * Execute garbage collection.
 349          * @private For internal use only
 350          * @param int $maxlifetime Maximum session life time (ignored)
 351          * @return bool Success
 352          */
 353         public function gc( $maxlifetime ) {
 354                 if ( self::$instance !== $this ) {
 355                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 356                 }
 357                 $before = date( 'YmdHis', time() );
 358                 $this->store->deleteObjectsExpiringBefore( $before );
 359                 return true;
 360         }
 361 }