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 $logger
 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          * Workaround for PHP5 bug
 167          *
 168          * PHP5 has a bug in handling boolean return values for
 169          * SessionHandlerInterface methods, it expects 0 or -1 instead of true or
 170          * false. See <https://wiki.php.net/rfc/session.user.return-value>.
 171          *
 172          * PHP7 and HHVM are not affected.
 173          *
 174          * @todo When we drop support for Zend PHP 5, this can be removed.
 175          * @return bool|int
 176          * @codeCoverageIgnore
 177          */
 178         protected static function returnSuccess() {
 179                 return defined( 'HHVM_VERSION' ) || version_compare( PHP_VERSION, '7.0.0', '>=' ) ? true : 0;
 180         }
 181
 182         /**
 183          * Workaround for PHP5 bug
 184          * @see self::returnSuccess()
 185          * @return bool|int
 186          * @codeCoverageIgnore
 187          */
 188         protected static function returnFailure() {
 189                 return defined( 'HHVM_VERSION' ) || version_compare( PHP_VERSION, '7.0.0', '>=' ) ? false : -1;
 190         }
 191
 192         /**
 193          * Initialize the session (handler)
 194          * @private For internal use only
 195          * @param string $save_path Path used to store session files (ignored)
 196          * @param string $session_name Session name (ignored)
 197          * @return bool|int Success (see self::returnSuccess())
 198          */
 199         public function open( $save_path, $session_name ) {
 200                 if ( self::$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                 return self::returnSuccess();
 207         }
 208
 209         /**
 210          * Close the session (handler)
 211          * @private For internal use only
 212          * @return bool|int Success (see self::returnSuccess())
 213          */
 214         public function close() {
 215                 if ( self::$instance !== $this ) {
 216                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 217                 }
 218                 $this->sessionFieldCache = [];
 219                 return self::returnSuccess();
 220         }
 221
 222         /**
 223          * Read session data
 224          * @private For internal use only
 225          * @param string $id Session id
 226          * @return string Session data
 227          */
 228         public function read( $id ) {
 229                 if ( self::$instance !== $this ) {
 230                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 231                 }
 232                 if ( !$this->enable ) {
 233                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 234                 }
 235
 236                 $session = $this->manager->getSessionById( $id, false );
 237                 if ( !$session ) {
 238                         return '';
 239                 }
 240                 $session->persist();
 241
 242                 $data = iterator_to_array( $session );
 243                 $this->sessionFieldCache[$id] = $data;
 244                 return (string)\Wikimedia\PhpSessionSerializer::encode( $data );
 245         }
 246
 247         /**
 248          * Write session data
 249          * @private For internal use only
 250          * @param string $id Session id
 251          * @param string $dataStr Session data. Not that you should ever call this
 252          *   directly, but note that this has the same issues with code injection
 253          *   via user-controlled data as does PHP's unserialize function.
 254          * @return bool|int Success (see self::returnSuccess())
 255          */
 256         public function write( $id, $dataStr ) {
 257                 if ( self::$instance !== $this ) {
 258                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 259                 }
 260                 if ( !$this->enable ) {
 261                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 262                 }
 263
 264                 $session = $this->manager->getSessionById( $id, true );
 265                 if ( !$session ) {
 266                         // This can happen under normal circumstances, if the session exists but is
 267                         // invalid. Let's emit a log warning instead of a PHP warning.
 268                         $this->logger->warning(
 269                                 __METHOD__ . ': Session "{session}" cannot be loaded, skipping write.',
 270                                 [
 271                                         'session' => $id,
 272                         ] );
 273                         return self::returnSuccess();
 274                 }
 275
 276                 // First, decode the string PHP handed us
 277                 $data = \Wikimedia\PhpSessionSerializer::decode( $dataStr );
 278                 if ( $data === null ) {
 279                         // @codeCoverageIgnoreStart
 280                         return self::returnFailure();
 281                         // @codeCoverageIgnoreEnd
 282                 }
 283
 284                 // Now merge the data into the Session object.
 285                 $changed = false;
 286                 $cache = isset( $this->sessionFieldCache[$id] ) ? $this->sessionFieldCache[$id] : [];
 287                 foreach ( $data as $key => $value ) {
 288                         if ( !array_key_exists( $key, $cache ) ) {
 289                                 if ( $session->exists( $key ) ) {
 290                                         // New in both, so ignore and log
 291                                         $this->logger->warning(
 292                                                 __METHOD__ . ": Key \"$key\" added in both Session and \$_SESSION!"
 293                                         );
 294                                 } else {
 295                                         // New in $_SESSION, keep it
 296                                         $session->set( $key, $value );
 297                                         $changed = true;
 298                                 }
 299                         } elseif ( $cache[$key] === $value ) {
 300                                 // Unchanged in $_SESSION, so ignore it
 301                         } elseif ( !$session->exists( $key ) ) {
 302                                 // Deleted in Session, keep but log
 303                                 $this->logger->warning(
 304                                         __METHOD__ . ": Key \"$key\" deleted in Session and changed in \$_SESSION!"
 305                                 );
 306                                 $session->set( $key, $value );
 307                                 $changed = true;
 308                         } elseif ( $cache[$key] === $session->get( $key ) ) {
 309                                 // Unchanged in Session, so keep it
 310                                 $session->set( $key, $value );
 311                                 $changed = true;
 312                         } else {
 313                                 // Changed in both, so ignore and log
 314                                 $this->logger->warning(
 315                                         __METHOD__ . ": Key \"$key\" changed in both Session and \$_SESSION!"
 316                                 );
 317                         }
 318                 }
 319                 // Anything deleted in $_SESSION and unchanged in Session should be deleted too
 320                 // (but not if $_SESSION can't represent it at all)
 321                 \Wikimedia\PhpSessionSerializer::setLogger( new \Psr\Log\NullLogger() );
 322                 foreach ( $cache as $key => $value ) {
 323                         if ( !array_key_exists( $key, $data ) && $session->exists( $key ) &&
 324                                 \Wikimedia\PhpSessionSerializer::encode( [ $key => true ] )
 325                         ) {
 326                                 if ( $cache[$key] === $session->get( $key ) ) {
 327                                         // Unchanged in Session, delete it
 328                                         $session->remove( $key );
 329                                         $changed = true;
 330                                 } else {
 331                                         // Changed in Session, ignore deletion and log
 332                                         $this->logger->warning(
 333                                                 __METHOD__ . ": Key \"$key\" changed in Session and deleted in \$_SESSION!"
 334                                         );
 335                                 }
 336                         }
 337                 }
 338                 \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 339
 340                 // Save and update cache if anything changed
 341                 if ( $changed ) {
 342                         if ( $this->warn ) {
 343                                 wfDeprecated( '$_SESSION', '1.27' );
 344                                 $this->logger->warning( 'Something wrote to $_SESSION!' );
 345                         }
 346
 347                         $session->save();
 348                         $this->sessionFieldCache[$id] = iterator_to_array( $session );
 349                 }
 350
 351                 $session->persist();
 352
 353                 return self::returnSuccess();
 354         }
 355
 356         /**
 357          * Destroy a session
 358          * @private For internal use only
 359          * @param string $id Session id
 360          * @return bool|int Success (see self::returnSuccess())
 361          */
 362         public function destroy( $id ) {
 363                 if ( self::$instance !== $this ) {
 364                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 365                 }
 366                 if ( !$this->enable ) {
 367                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 368                 }
 369                 $session = $this->manager->getSessionById( $id, false );
 370                 if ( $session ) {
 371                         $session->clear();
 372                 }
 373                 return self::returnSuccess();
 374         }
 375
 376         /**
 377          * Execute garbage collection.
 378          * @private For internal use only
 379          * @param int $maxlifetime Maximum session life time (ignored)
 380          * @return bool|int Success (see self::returnSuccess())
 381          * @codeCoverageIgnore See T135576
 382          */
 383         public function gc( $maxlifetime ) {
 384                 if ( self::$instance !== $this ) {
 385                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 386                 }
 387                 $before = date( 'YmdHis', time() );
 388                 $this->store->deleteObjectsExpiringBefore( $before );
 389                 return self::returnSuccess();
 390         }
 391 }