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  * @todo Once we drop support for PHP < 5.4, use SessionHandlerInterface
  32  *  (should just be a matter of adding "implements SessionHandlerInterface" and
  33  *  changing the session_set_save_handler() call).
  34  * @ingroup Session
  35  * @since 1.27
  36  */
  37 class PHPSessionHandler {
  38         /** @var PHPSessionHandler */
  39         protected static $instance = null;
  40
  41         /** @var bool Whether PHP session handling is enabled */
  42         protected $enable = false;
  43         protected $warn = true;
  44
  45         /** @var SessionManager|null */
  46         protected $manager;
  47
  48         /** @var BagOStuff|null */
  49         protected $store;
  50
  51         /** @var LoggerInterface */
  52         protected $logger;
  53
  54         /** @var array Track original session fields for later modification check */
  55         protected $sessionFieldCache = array();
  56
  57         protected function __construct( SessionManager $manager ) {
  58                 $this->setEnableFlags(
  59                         \RequestContext::getMain()->getConfig()->get( 'PHPSessionHandling' )
  60                 );
  61                 $manager->setupPHPSessionHandler( $this );
  62         }
  63
  64         /**
  65          * Set $this->enable and $this->warn
  66          *
  67          * Separate just because there doesn't seem to be a good way to test it
  68          * otherwise.
  69          *
  70          * @param string $PHPSessionHandling See $wgPHPSessionHandling
  71          */
  72         private function setEnableFlags( $PHPSessionHandling ) {
  73                 switch ( $PHPSessionHandling ) {
  74                         case 'enable':
  75                                 $this->enable = true;
  76                                 $this->warn = false;
  77                                 break;
  78
  79                         case 'warn':
  80                                 $this->enable = true;
  81                                 $this->warn = true;
  82                                 break;
  83
  84                         case 'disable':
  85                                 $this->enable = false;
  86                                 $this->warn = false;
  87                                 break;
  88                 }
  89         }
  90
  91         /**
  92          * Test whether the handler is installed
  93          * @return bool
  94          */
  95         public static function isInstalled() {
  96                 return (bool)self::$instance;
  97         }
  98
  99         /**
 100          * Test whether the handler is installed and enabled
 101          * @return bool
 102          */
 103         public static function isEnabled() {
 104                 return self::$instance && self::$instance->enable;
 105         }
 106
 107         /**
 108          * Install a session handler for the current web request
 109          * @param SessionManager $manager
 110          */
 111         public static function install( SessionManager $manager ) {
 112                 if ( self::$instance ) {
 113                         $manager->setupPHPSessionHandler( self::$instance );
 114                         return;
 115                 }
 116
 117                 self::$instance = new self( $manager );
 118
 119                 // Close any auto-started session, before we replace it
 120                 session_write_close();
 121
 122                 // Tell PHP not to mess with cookies itself
 123                 ini_set( 'session.use_cookies', 0 );
 124                 ini_set( 'session.use_trans_sid', 0 );
 125
 126                 // Also set a sane serialization handler
 127                 \Wikimedia\PhpSessionSerializer::setSerializeHandler();
 128
 129                 session_set_save_handler(
 130                         array( self::$instance, 'open' ),
 131                         array( self::$instance, 'close' ),
 132                         array( self::$instance, 'read' ),
 133                         array( self::$instance, 'write' ),
 134                         array( self::$instance, 'destroy' ),
 135                         array( self::$instance, 'gc' )
 136                 );
 137
 138                 // It's necessary to register a shutdown function to call session_write_close(),
 139                 // because by the time the request shutdown function for the session module is
 140                 // called, other needed objects may have already been destroyed. Shutdown functions
 141                 // registered this way are called before object destruction.
 142                 register_shutdown_function( array( self::$instance, 'handleShutdown' ) );
 143         }
 144
 145         /**
 146          * Set the manager, store, and logger
 147          * @private Use self::install().
 148          * @param SessionManager $manager
 149          * @param BagOStuff $store
 150          * @param LoggerInterface $store
 151          */
 152         public function setManager(
 153                 SessionManager $manager, BagOStuff $store, LoggerInterface $logger
 154         ) {
 155                 if ( $this->manager !== $manager ) {
 156                         // Close any existing session before we change stores
 157                         if ( $this->manager ) {
 158                                 session_write_close();
 159                         }
 160                         $this->manager = $manager;
 161                         $this->store = $store;
 162                         $this->logger = $logger;
 163                         \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 164                 }
 165         }
 166
 167         /**
 168          * Initialize the session (handler)
 169          * @private For internal use only
 170          * @param string $save_path Path used to store session files (ignored)
 171          * @param string $session_name Session name (ignored)
 172          * @return bool Success
 173          */
 174         public function open( $save_path, $session_name ) {
 175                 if ( self::$instance !== $this ) {
 176                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 177                 }
 178                 if ( !$this->enable ) {
 179                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 180                 }
 181                 return true;
 182         }
 183
 184         /**
 185          * Close the session (handler)
 186          * @private For internal use only
 187          * @return bool Success
 188          */
 189         public function close() {
 190                 if ( self::$instance !== $this ) {
 191                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 192                 }
 193                 $this->sessionFieldCache = array();
 194                 return true;
 195         }
 196
 197         /**
 198          * Read session data
 199          * @private For internal use only
 200          * @param string $id Session id
 201          * @return string Session data
 202          */
 203         public function read( $id ) {
 204                 if ( self::$instance !== $this ) {
 205                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 206                 }
 207                 if ( !$this->enable ) {
 208                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 209                 }
 210
 211                 $session = $this->manager->getSessionById( $id, false );
 212                 if ( !$session ) {
 213                         return '';
 214                 }
 215                 $session->persist();
 216
 217                 $data = iterator_to_array( $session );
 218                 $this->sessionFieldCache[$id] = $data;
 219                 return (string)\Wikimedia\PhpSessionSerializer::encode( $data );
 220         }
 221
 222         /**
 223          * Write session data
 224          * @private For internal use only
 225          * @param string $id Session id
 226          * @param string $dataStr Session data. Not that you should ever call this
 227          *   directly, but note that this has the same issues with code injection
 228          *   via user-controlled data as does PHP's unserialize function.
 229          * @return bool Success
 230          */
 231         public function write( $id, $dataStr ) {
 232                 if ( self::$instance !== $this ) {
 233                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 234                 }
 235                 if ( !$this->enable ) {
 236                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 237                 }
 238
 239                 $session = $this->manager->getSessionById( $id, true );
 240                 if ( !$session ) {
 241                         // This can happen under normal circumstances, if the session exists but is
 242                         // invalid. Let's emit a log warning instead of a PHP warning.
 243                         $this->logger->warning(
 244                                 __METHOD__ . ": Session \"$id\" cannot be loaded, skipping write."
 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] : array();
 260                 foreach ( $data as $key => $value ) {
 261                         if ( !isset( $cache[$key] ) ) {
 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 ( !isset( $data[$key] ) && $session->exists( $key ) &&
 297                                 \Wikimedia\PhpSessionSerializer::encode( array( $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
 364         /**
 365          * Shutdown function.
 366          *
 367          * See the comment inside self::install for rationale.
 368          * @codeCoverageIgnore
 369          * @private For internal use only
 370          */
 371         public function handleShutdown() {
 372                 if ( $this->enable ) {
 373                         session_write_close();
 374                 }
 375         }
 376
 377 }