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                 // @codeCoverageIgnoreStart
 115                 if ( defined( 'MW_NO_SESSION_HANDLER' ) ) {
 116                         throw new \BadMethodCallException( 'MW_NO_SESSION_HANDLER is defined' );
 117                 }
 118                 // @codeCoverageIgnoreEnd
 119
 120                 self::$instance = new self( $manager );
 121
 122                 // Close any auto-started session, before we replace it
 123                 session_write_close();
 124
 125                 // Tell PHP not to mess with cookies itself
 126                 ini_set( 'session.use_cookies', 0 );
 127                 ini_set( 'session.use_trans_sid', 0 );
 128
 129                 // T124510: Disable automatic PHP session related cache headers.
 130                 // MediaWiki adds it's own headers and the default PHP behavior may
 131                 // set headers such as 'Pragma: no-cache' that cause problems with
 132                 // some user agents.
 133                 session_cache_limiter( '' );
 134
 135                 // Also set a sane serialization handler
 136                 \Wikimedia\PhpSessionSerializer::setSerializeHandler();
 137
 138                 // Register this as the save handler, and register an appropriate
 139                 // shutdown function.
 140                 session_set_save_handler( self::$instance, true );
 141         }
 142
 143         /**
 144          * Set the manager, store, and logger
 145          * @private Use self::install().
 146          * @param SessionManager $manager
 147          * @param BagOStuff $store
 148          * @param LoggerInterface $store
 149          */
 150         public function setManager(
 151                 SessionManager $manager, BagOStuff $store, LoggerInterface $logger
 152         ) {
 153                 if ( $this->manager !== $manager ) {
 154                         // Close any existing session before we change stores
 155                         if ( $this->manager ) {
 156                                 session_write_close();
 157                         }
 158                         $this->manager = $manager;
 159                         $this->store = $store;
 160                         $this->logger = $logger;
 161                         \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 162                 }
 163         }
 164
 165         /**
 166          * Initialize the session (handler)
 167          * @private For internal use only
 168          * @param string $save_path Path used to store session files (ignored)
 169          * @param string $session_name Session name (ignored)
 170          * @return bool Success
 171          */
 172         public function open( $save_path, $session_name ) {
 173                 if ( self::$instance !== $this ) {
 174                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 175                 }
 176                 if ( !$this->enable ) {
 177                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 178                 }
 179                 return true;
 180         }
 181
 182         /**
 183          * Close the session (handler)
 184          * @private For internal use only
 185          * @return bool Success
 186          */
 187         public function close() {
 188                 if ( self::$instance !== $this ) {
 189                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 190                 }
 191                 $this->sessionFieldCache = [];
 192                 return true;
 193         }
 194
 195         /**
 196          * Read session data
 197          * @private For internal use only
 198          * @param string $id Session id
 199          * @return string Session data
 200          */
 201         public function read( $id ) {
 202                 if ( self::$instance !== $this ) {
 203                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 204                 }
 205                 if ( !$this->enable ) {
 206                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 207                 }
 208
 209                 $session = $this->manager->getSessionById( $id, false );
 210                 if ( !$session ) {
 211                         return '';
 212                 }
 213                 $session->persist();
 214
 215                 $data = iterator_to_array( $session );
 216                 $this->sessionFieldCache[$id] = $data;
 217                 return (string)\Wikimedia\PhpSessionSerializer::encode( $data );
 218         }
 219
 220         /**
 221          * Write session data
 222          * @private For internal use only
 223          * @param string $id Session id
 224          * @param string $dataStr Session data. Not that you should ever call this
 225          *   directly, but note that this has the same issues with code injection
 226          *   via user-controlled data as does PHP's unserialize function.
 227          * @return bool Success
 228          */
 229         public function write( $id, $dataStr ) {
 230                 if ( self::$instance !== $this ) {
 231                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 232                 }
 233                 if ( !$this->enable ) {
 234                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 235                 }
 236
 237                 $session = $this->manager->getSessionById( $id, true );
 238                 if ( !$session ) {
 239                         // This can happen under normal circumstances, if the session exists but is
 240                         // invalid. Let's emit a log warning instead of a PHP warning.
 241                         $this->logger->warning(
 242                                 __METHOD__ . ': Session "{session}" cannot be loaded, skipping write.',
 243                                 [
 244                                         'session' => $id,
 245                         ] );
 246                         return true;
 247                 }
 248
 249                 // First, decode the string PHP handed us
 250                 $data = \Wikimedia\PhpSessionSerializer::decode( $dataStr );
 251                 if ( $data === null ) {
 252                         // @codeCoverageIgnoreStart
 253                         return false;
 254                         // @codeCoverageIgnoreEnd
 255                 }
 256
 257                 // Now merge the data into the Session object.
 258                 $changed = false;
 259                 $cache = isset( $this->sessionFieldCache[$id] ) ? $this->sessionFieldCache[$id] : [];
 260                 foreach ( $data as $key => $value ) {
 261                         if ( !array_key_exists( $key, $cache ) ) {
 262                                 if ( $session->exists( $key ) ) {
 263                                         // New in both, so ignore and log
 264                                         $this->logger->warning(
 265                                                 __METHOD__ . ": Key \"$key\" added in both Session and \$_SESSION!"
 266                                         );
 267                                 } else {
 268                                         // New in $_SESSION, keep it
 269                                         $session->set( $key, $value );
 270                                         $changed = true;
 271                                 }
 272                         } elseif ( $cache[$key] === $value ) {
 273                                 // Unchanged in $_SESSION, so ignore it
 274                         } elseif ( !$session->exists( $key ) ) {
 275                                 // Deleted in Session, keep but log
 276                                 $this->logger->warning(
 277                                         __METHOD__ . ": Key \"$key\" deleted in Session and changed in \$_SESSION!"
 278                                 );
 279                                 $session->set( $key, $value );
 280                                 $changed = true;
 281                         } elseif ( $cache[$key] === $session->get( $key ) ) {
 282                                 // Unchanged in Session, so keep it
 283                                 $session->set( $key, $value );
 284                                 $changed = true;
 285                         } else {
 286                                 // Changed in both, so ignore and log
 287                                 $this->logger->warning(
 288                                         __METHOD__ . ": Key \"$key\" changed in both Session and \$_SESSION!"
 289                                 );
 290                         }
 291                 }
 292                 // Anything deleted in $_SESSION and unchanged in Session should be deleted too
 293                 // (but not if $_SESSION can't represent it at all)
 294                 \Wikimedia\PhpSessionSerializer::setLogger( new \Psr\Log\NullLogger() );
 295                 foreach ( $cache as $key => $value ) {
 296                         if ( !array_key_exists( $key, $data ) && $session->exists( $key ) &&
 297                                 \Wikimedia\PhpSessionSerializer::encode( [ $key => true ] )
 298                         ) {
 299                                 if ( $cache[$key] === $session->get( $key ) ) {
 300                                         // Unchanged in Session, delete it
 301                                         $session->remove( $key );
 302                                         $changed = true;
 303                                 } else {
 304                                         // Changed in Session, ignore deletion and log
 305                                         $this->logger->warning(
 306                                                 __METHOD__ . ": Key \"$key\" changed in Session and deleted in \$_SESSION!"
 307                                         );
 308                                 }
 309                         }
 310                 }
 311                 \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 312
 313                 // Save and update cache if anything changed
 314                 if ( $changed ) {
 315                         if ( $this->warn ) {
 316                                 wfDeprecated( '$_SESSION', '1.27' );
 317                                 $this->logger->warning( 'Something wrote to $_SESSION!' );
 318                         }
 319
 320                         $session->save();
 321                         $this->sessionFieldCache[$id] = iterator_to_array( $session );
 322                 }
 323
 324                 $session->persist();
 325
 326                 return true;
 327         }
 328
 329         /**
 330          * Destroy a session
 331          * @private For internal use only
 332          * @param string $id Session id
 333          * @return bool Success
 334          */
 335         public function destroy( $id ) {
 336                 if ( self::$instance !== $this ) {
 337                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 338                 }
 339                 if ( !$this->enable ) {
 340                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 341                 }
 342                 $session = $this->manager->getSessionById( $id, false );
 343                 if ( $session ) {
 344                         $session->clear();
 345                 }
 346                 return true;
 347         }
 348
 349         /**
 350          * Execute garbage collection.
 351          * @private For internal use only
 352          * @param int $maxlifetime Maximum session life time (ignored)
 353          * @return bool Success
 354          */
 355         public function gc( $maxlifetime ) {
 356                 if ( self::$instance !== $this ) {
 357                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 358                 }
 359                 $before = date( 'YmdHis', time() );
 360                 $this->store->deleteObjectsExpiringBefore( $before );
 361                 return true;
 362         }
 363 }