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( $manager );
 121
 122                 // Close any auto-started session, before we replace it
 123                 session_write_close();
 124
 125                 try {
 126                         \Wikimedia\suppressWarnings();
 127
 128                         // Tell PHP not to mess with cookies itself
 129                         ini_set( 'session.use_cookies', 0 );
 130                         ini_set( 'session.use_trans_sid', 0 );
 131
 132                         // T124510: Disable automatic PHP session related cache headers.
 133                         // MediaWiki adds it's own headers and the default PHP behavior may
 134                         // set headers such as 'Pragma: no-cache' that cause problems with
 135                         // some user agents.
 136                         session_cache_limiter( '' );
 137
 138                         // Also set a sane serialization handler
 139                         \Wikimedia\PhpSessionSerializer::setSerializeHandler();
 140
 141                         // Register this as the save handler, and register an appropriate
 142                         // shutdown function.
 143                         session_set_save_handler( self::$instance, true );
 144                 } finally {
 145                         \Wikimedia\restoreWarnings();
 146                 }
 147         }
 148
 149         /**
 150          * Set the manager, store, and logger
 151          * @private Use self::install().
 152          * @param SessionManager $manager
 153          * @param BagOStuff $store
 154          * @param LoggerInterface $logger
 155          */
 156         public function setManager(
 157                 SessionManager $manager, BagOStuff $store, LoggerInterface $logger
 158         ) {
 159                 if ( $this->manager !== $manager ) {
 160                         // Close any existing session before we change stores
 161                         if ( $this->manager ) {
 162                                 session_write_close();
 163                         }
 164                         $this->manager = $manager;
 165                         $this->store = $store;
 166                         $this->logger = $logger;
 167                         \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 168                 }
 169         }
 170
 171         /**
 172          * Initialize the session (handler)
 173          * @private For internal use only
 174          * @param string $save_path Path used to store session files (ignored)
 175          * @param string $session_name Session name (ignored)
 176          * @return true
 177          */
 178         public function open( $save_path, $session_name ) {
 179                 if ( self::$instance !== $this ) {
 180                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 181                 }
 182                 if ( !$this->enable ) {
 183                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 184                 }
 185                 return true;
 186         }
 187
 188         /**
 189          * Close the session (handler)
 190          * @private For internal use only
 191          * @return true
 192          */
 193         public function close() {
 194                 if ( self::$instance !== $this ) {
 195                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 196                 }
 197                 $this->sessionFieldCache = [];
 198                 return true;
 199         }
 200
 201         /**
 202          * Read session data
 203          * @private For internal use only
 204          * @param string $id Session id
 205          * @return string Session data
 206          */
 207         public function read( $id ) {
 208                 if ( self::$instance !== $this ) {
 209                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 210                 }
 211                 if ( !$this->enable ) {
 212                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 213                 }
 214
 215                 $session = $this->manager->getSessionById( $id, false );
 216                 if ( !$session ) {
 217                         return '';
 218                 }
 219                 $session->persist();
 220
 221                 $data = iterator_to_array( $session );
 222                 $this->sessionFieldCache[$id] = $data;
 223                 return (string)\Wikimedia\PhpSessionSerializer::encode( $data );
 224         }
 225
 226         /**
 227          * Write session data
 228          * @private For internal use only
 229          * @param string $id Session id
 230          * @param string $dataStr Session data. Not that you should ever call this
 231          *   directly, but note that this has the same issues with code injection
 232          *   via user-controlled data as does PHP's unserialize function.
 233          * @return bool
 234          */
 235         public function write( $id, $dataStr ) {
 236                 if ( self::$instance !== $this ) {
 237                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 238                 }
 239                 if ( !$this->enable ) {
 240                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 241                 }
 242
 243                 $session = $this->manager->getSessionById( $id, true );
 244                 if ( !$session ) {
 245                         // This can happen under normal circumstances, if the session exists but is
 246                         // invalid. Let's emit a log warning instead of a PHP warning.
 247                         $this->logger->warning(
 248                                 __METHOD__ . ': Session "{session}" cannot be loaded, skipping write.',
 249                                 [
 250                                         'session' => $id,
 251                         ] );
 252                         return true;
 253                 }
 254
 255                 // First, decode the string PHP handed us
 256                 $data = \Wikimedia\PhpSessionSerializer::decode( $dataStr );
 257                 if ( $data === null ) {
 258                         // @codeCoverageIgnoreStart
 259                         return false;
 260                         // @codeCoverageIgnoreEnd
 261                 }
 262
 263                 // Now merge the data into the Session object.
 264                 $changed = false;
 265                 $cache = $this->sessionFieldCache[$id] ?? [];
 266                 foreach ( $data as $key => $value ) {
 267                         if ( !array_key_exists( $key, $cache ) ) {
 268                                 if ( $session->exists( $key ) ) {
 269                                         // New in both, so ignore and log
 270                                         $this->logger->warning(
 271                                                 __METHOD__ . ": Key \"$key\" added in both Session and \$_SESSION!"
 272                                         );
 273                                 } else {
 274                                         // New in $_SESSION, keep it
 275                                         $session->set( $key, $value );
 276                                         $changed = true;
 277                                 }
 278                         } elseif ( $cache[$key] === $value ) {
 279                                 // Unchanged in $_SESSION, so ignore it
 280                         } elseif ( !$session->exists( $key ) ) {
 281                                 // Deleted in Session, keep but log
 282                                 $this->logger->warning(
 283                                         __METHOD__ . ": Key \"$key\" deleted in Session and changed in \$_SESSION!"
 284                                 );
 285                                 $session->set( $key, $value );
 286                                 $changed = true;
 287                         } elseif ( $cache[$key] === $session->get( $key ) ) {
 288                                 // Unchanged in Session, so keep it
 289                                 $session->set( $key, $value );
 290                                 $changed = true;
 291                         } else {
 292                                 // Changed in both, so ignore and log
 293                                 $this->logger->warning(
 294                                         __METHOD__ . ": Key \"$key\" changed in both Session and \$_SESSION!"
 295                                 );
 296                         }
 297                 }
 298                 // Anything deleted in $_SESSION and unchanged in Session should be deleted too
 299                 // (but not if $_SESSION can't represent it at all)
 300                 \Wikimedia\PhpSessionSerializer::setLogger( new \Psr\Log\NullLogger() );
 301                 foreach ( $cache as $key => $value ) {
 302                         if ( !array_key_exists( $key, $data ) && $session->exists( $key ) &&
 303                                 \Wikimedia\PhpSessionSerializer::encode( [ $key => true ] )
 304                         ) {
 305                                 if ( $cache[$key] === $session->get( $key ) ) {
 306                                         // Unchanged in Session, delete it
 307                                         $session->remove( $key );
 308                                         $changed = true;
 309                                 } else {
 310                                         // Changed in Session, ignore deletion and log
 311                                         $this->logger->warning(
 312                                                 __METHOD__ . ": Key \"$key\" changed in Session and deleted in \$_SESSION!"
 313                                         );
 314                                 }
 315                         }
 316                 }
 317                 \Wikimedia\PhpSessionSerializer::setLogger( $this->logger );
 318
 319                 // Save and update cache if anything changed
 320                 if ( $changed ) {
 321                         if ( $this->warn ) {
 322                                 wfDeprecated( '$_SESSION', '1.27' );
 323                                 $this->logger->warning( 'Something wrote to $_SESSION!' );
 324                         }
 325
 326                         $session->save();
 327                         $this->sessionFieldCache[$id] = iterator_to_array( $session );
 328                 }
 329
 330                 $session->persist();
 331
 332                 return true;
 333         }
 334
 335         /**
 336          * Destroy a session
 337          * @private For internal use only
 338          * @param string $id Session id
 339          * @return true
 340          */
 341         public function destroy( $id ) {
 342                 if ( self::$instance !== $this ) {
 343                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 344                 }
 345                 if ( !$this->enable ) {
 346                         throw new \BadMethodCallException( 'Attempt to use PHP session management' );
 347                 }
 348                 $session = $this->manager->getSessionById( $id, false );
 349                 if ( $session ) {
 350                         $session->clear();
 351                 }
 352                 return true;
 353         }
 354
 355         /**
 356          * Execute garbage collection.
 357          * @private For internal use only
 358          * @param int $maxlifetime Maximum session life time (ignored)
 359          * @return true
 360          * @codeCoverageIgnore See T135576
 361          */
 362         public function gc( $maxlifetime ) {
 363                 if ( self::$instance !== $this ) {
 364                         throw new \UnexpectedValueException( __METHOD__ . ': Wrong instance called!' );
 365                 }
 366                 $before = date( 'YmdHis', time() );
 367                 $this->store->deleteObjectsExpiringBefore( $before );
 368                 return true;
 369         }
 370 }