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[mediawiki.git] / includes / session / SessionBackend.php

<?php
/**
 * MediaWiki session backend
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Session
 */

namespace MediaWiki\Session;

use CachedBagOStuff;
use Psr\Log\LoggerInterface;
use User;
use WebRequest;

/**
 * This is the actual workhorse for Session.
 *
 * Most code does not need to use this class, you want \MediaWiki\Session\Session.
 * The exceptions are SessionProviders and SessionMetadata hook functions,
 * which get an instance of this class rather than Session.
 *
 * The reasons for this split are:
 * 1. A session can be attached to multiple requests, but we want the Session
 *    object to have some features that correspond to just one of those
 *    requests.
 * 2. We want reasonable garbage collection behavior, but we also want the
 *    SessionManager to hold a reference to every active session so it can be
 *    saved when the request ends.
 *
 * @ingroup Session
 * @since 1.27
 */
final class SessionBackend {
        /** @var SessionId */
        private $id;

        private $persist = false;
        private $remember = false;
        private $forceHTTPS = false;

        /** @var array|null */
        private $data = null;

        private $forcePersist = false;
        private $metaDirty = false;
        private $dataDirty = false;

        /** @var string Used to detect subarray modifications */
        private $dataHash = null;

        /** @var CachedBagOStuff */
        private $store;

        /** @var LoggerInterface */
        private $logger;

        /** @var int */
        private $lifetime;

        /** @var User */
        private $user;

        private $curIndex = 0;

        /** @var WebRequest[] Session requests */
        private $requests = [];

        /** @var SessionProvider provider */
        private $provider;

        /** @var array|null provider-specified metadata */
        private $providerMetadata = null;

        private $expires = 0;
        private $loggedOut = 0;
        private $delaySave = 0;

        private $usePhpSessionHandling = true;
        private $checkPHPSessionRecursionGuard = false;

        private $shutdown = false;

        /**
         * @param SessionId $id Session ID object
         * @param SessionInfo $info Session info to populate from
         * @param CachedBagOStuff $store Backend data store
         * @param LoggerInterface $logger
         * @param int $lifetime Session data lifetime in seconds
         */
        public function __construct(
                SessionId $id, SessionInfo $info, CachedBagOStuff $store, LoggerInterface $logger, $lifetime
        ) {
                $phpSessionHandling = \RequestContext::getMain()->getConfig()->get( 'PHPSessionHandling' );
                $this->usePhpSessionHandling = $phpSessionHandling !== 'disable';

                if ( $info->getUserInfo() && !$info->getUserInfo()->isVerified() ) {
                        throw new \InvalidArgumentException(
                                "Refusing to create session for unverified user {$info->getUserInfo()}"
                        );
                }
                if ( $info->getProvider() === null ) {
                        throw new \InvalidArgumentException( 'Cannot create session without a provider' );
                }
                if ( $info->getId() !== $id->getId() ) {
                        throw new \InvalidArgumentException( 'SessionId and SessionInfo don\'t match' );
                }

                $this->id = $id;
                $this->user = $info->getUserInfo() ? $info->getUserInfo()->getUser() : new User;
                $this->store = $store;
                $this->logger = $logger;
                $this->lifetime = $lifetime;
                $this->provider = $info->getProvider();
                $this->persist = $info->wasPersisted();
                $this->remember = $info->wasRemembered();
                $this->forceHTTPS = $info->forceHTTPS();
                $this->providerMetadata = $info->getProviderMetadata();

                $blob = $store->get( wfMemcKey( 'MWSession', (string)$this->id ) );
                if ( !is_array( $blob ) ||
                        !isset( $blob['metadata'] ) || !is_array( $blob['metadata'] ) ||
                        !isset( $blob['data'] ) || !is_array( $blob['data'] )
                ) {
                        $this->data = [];
                        $this->dataDirty = true;
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" is unsaved, marking dirty in constructor',
                                [
                                        'session' => $this->id,
                        ] );
                } else {
                        $this->data = $blob['data'];
                        if ( isset( $blob['metadata']['loggedOut'] ) ) {
                                $this->loggedOut = (int)$blob['metadata']['loggedOut'];
                        }
                        if ( isset( $blob['metadata']['expires'] ) ) {
                                $this->expires = (int)$blob['metadata']['expires'];
                        } else {
                                $this->metaDirty = true;
                                $this->logger->debug(
                                        'SessionBackend "{session}" metadata dirty due to missing expiration timestamp',
                                [
                                        'session' => $this->id,
                                ] );
                        }
                }
                $this->dataHash = md5( serialize( $this->data ) );
        }

        /**
         * Return a new Session for this backend
         * @param WebRequest $request
         * @return Session
         */
        public function getSession( WebRequest $request ) {
                $index = ++$this->curIndex;
                $this->requests[$index] = $request;
                $session = new Session( $this, $index, $this->logger );
                return $session;
        }

        /**
         * Deregister a Session
         * @private For use by \MediaWiki\Session\Session::__destruct() only
         * @param int $index
         */
        public function deregisterSession( $index ) {
                unset( $this->requests[$index] );
                if ( !$this->shutdown && !count( $this->requests ) ) {
                        $this->save( true );
                        $this->provider->getManager()->deregisterSessionBackend( $this );
                }
        }

        /**
         * Shut down a session
         * @private For use by \MediaWiki\Session\SessionManager::shutdown() only
         */
        public function shutdown() {
                $this->save( true );
                $this->shutdown = true;
        }

        /**
         * Returns the session ID.
         * @return string
         */
        public function getId() {
                return (string)$this->id;
        }

        /**
         * Fetch the SessionId object
         * @private For internal use by WebRequest
         * @return SessionId
         */
        public function getSessionId() {
                return $this->id;
        }

        /**
         * Changes the session ID
         * @return string New ID (might be the same as the old)
         */
        public function resetId() {
                if ( $this->provider->persistsSessionId() ) {
                        $oldId = (string)$this->id;
                        $restart = $this->usePhpSessionHandling && $oldId === session_id() &&
                                PHPSessionHandler::isEnabled();

                        if ( $restart ) {
                                // If this session is the one behind PHP's $_SESSION, we need
                                // to close then reopen it.
                                session_write_close();
                        }

                        $this->provider->getManager()->changeBackendId( $this );
                        $this->provider->sessionIdWasReset( $this, $oldId );
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" metadata dirty due to ID reset (formerly "{oldId}")',
                                [
                                        'session' => $this->id,
                                        'oldId' => $oldId,
                        ] );

                        if ( $restart ) {
                                session_id( (string)$this->id );
                                \MediaWiki\quietCall( 'session_start' );
                        }

                        $this->autosave();

                        // Delete the data for the old session ID now
                        $this->store->delete( wfMemcKey( 'MWSession', $oldId ) );
                }
        }

        /**
         * Fetch the SessionProvider for this session
         * @return SessionProviderInterface
         */
        public function getProvider() {
                return $this->provider;
        }

        /**
         * Indicate whether this session is persisted across requests
         *
         * For example, if cookies are set.
         *
         * @return bool
         */
        public function isPersistent() {
                return $this->persist;
        }

        /**
         * Make this session persisted across requests
         *
         * If the session is already persistent, equivalent to calling
         * $this->renew().
         */
        public function persist() {
                if ( !$this->persist ) {
                        $this->persist = true;
                        $this->forcePersist = true;
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" force-persist due to persist()',
                                [
                                        'session' => $this->id,
                        ] );
                        $this->autosave();
                } else {
                        $this->renew();
                }
        }

        /**
         * Make this session not persisted across requests
         */
        public function unpersist() {
                if ( $this->persist ) {
                        // Close the PHP session, if we're the one that's open
                        if ( $this->usePhpSessionHandling && PHPSessionHandler::isEnabled() &&
                                session_id() === (string)$this->id
                        ) {
                                $this->logger->debug(
                                        'SessionBackend "{session}" Closing PHP session for unpersist',
                                        [ 'session' => $this->id ]
                                );
                                session_write_close();
                                session_id( '' );
                        }

                        $this->persist = false;
                        $this->forcePersist = true;
                        $this->metaDirty = true;

                        // Delete the session data, so the local cache-only write in
                        // self::save() doesn't get things out of sync with the backend.
                        $this->store->delete( wfMemcKey( 'MWSession', (string)$this->id ) );

                        $this->autosave();
                }
        }

        /**
         * Indicate whether the user should be remembered independently of the
         * session ID.
         * @return bool
         */
        public function shouldRememberUser() {
                return $this->remember;
        }

        /**
         * Set whether the user should be remembered independently of the session
         * ID.
         * @param bool $remember
         */
        public function setRememberUser( $remember ) {
                if ( $this->remember !== (bool)$remember ) {
                        $this->remember = (bool)$remember;
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" metadata dirty due to remember-user change',
                                [
                                        'session' => $this->id,
                        ] );
                        $this->autosave();
                }
        }

        /**
         * Returns the request associated with a Session
         * @param int $index Session index
         * @return WebRequest
         */
        public function getRequest( $index ) {
                if ( !isset( $this->requests[$index] ) ) {
                        throw new \InvalidArgumentException( 'Invalid session index' );
                }
                return $this->requests[$index];
        }

        /**
         * Returns the authenticated user for this session
         * @return User
         */
        public function getUser() {
                return $this->user;
        }

        /**
         * Fetch the rights allowed the user when this session is active.
         * @return null|string[] Allowed user rights, or null to allow all.
         */
        public function getAllowedUserRights() {
                return $this->provider->getAllowedUserRights( $this );
        }

        /**
         * Indicate whether the session user info can be changed
         * @return bool
         */
        public function canSetUser() {
                return $this->provider->canChangeUser();
        }

        /**
         * Set a new user for this session
         * @note This should only be called when the user has been authenticated via a login process
         * @param User $user User to set on the session.
         *   This may become a "UserValue" in the future, or User may be refactored
         *   into such.
         */
        public function setUser( $user ) {
                if ( !$this->canSetUser() ) {
                        throw new \BadMethodCallException(
                                'Cannot set user on this session; check $session->canSetUser() first'
                        );
                }

                $this->user = $user;
                $this->metaDirty = true;
                $this->logger->debug(
                        'SessionBackend "{session}" metadata dirty due to user change',
                        [
                                'session' => $this->id,
                ] );
                $this->autosave();
        }

        /**
         * Get a suggested username for the login form
         * @param int $index Session index
         * @return string|null
         */
        public function suggestLoginUsername( $index ) {
                if ( !isset( $this->requests[$index] ) ) {
                        throw new \InvalidArgumentException( 'Invalid session index' );
                }
                return $this->provider->suggestLoginUsername( $this->requests[$index] );
        }

        /**
         * Whether HTTPS should be forced
         * @return bool
         */
        public function shouldForceHTTPS() {
                return $this->forceHTTPS;
        }

        /**
         * Set whether HTTPS should be forced
         * @param bool $force
         */
        public function setForceHTTPS( $force ) {
                if ( $this->forceHTTPS !== (bool)$force ) {
                        $this->forceHTTPS = (bool)$force;
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" metadata dirty due to force-HTTPS change',
                                [
                                        'session' => $this->id,
                        ] );
                        $this->autosave();
                }
        }

        /**
         * Fetch the "logged out" timestamp
         * @return int
         */
        public function getLoggedOutTimestamp() {
                return $this->loggedOut;
        }

        /**
         * Set the "logged out" timestamp
         * @param int $ts
         */
        public function setLoggedOutTimestamp( $ts = null ) {
                $ts = (int)$ts;
                if ( $this->loggedOut !== $ts ) {
                        $this->loggedOut = $ts;
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" metadata dirty due to logged-out-timestamp change',
                                [
                                        'session' => $this->id,
                        ] );
                        $this->autosave();
                }
        }

        /**
         * Fetch provider metadata
         * @protected For use by SessionProvider subclasses only
         * @return array|null
         */
        public function getProviderMetadata() {
                return $this->providerMetadata;
        }

        /**
         * Set provider metadata
         * @protected For use by SessionProvider subclasses only
         * @param array|null $metadata
         */
        public function setProviderMetadata( $metadata ) {
                if ( $metadata !== null && !is_array( $metadata ) ) {
                        throw new \InvalidArgumentException( '$metadata must be an array or null' );
                }
                if ( $this->providerMetadata !== $metadata ) {
                        $this->providerMetadata = $metadata;
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{session}" metadata dirty due to provider metadata change',
                                [
                                        'session' => $this->id,
                        ] );
                        $this->autosave();
                }
        }

        /**
         * Fetch the session data array
         *
         * Note the caller is responsible for calling $this->dirty() if anything in
         * the array is changed.
         *
         * @private For use by \MediaWiki\Session\Session only.
         * @return array
         */
        public function &getData() {
                return $this->data;
        }

        /**
         * Add data to the session.
         *
         * Overwrites any existing data under the same keys.
         *
         * @param array $newData Key-value pairs to add to the session
         */
        public function addData( array $newData ) {
                $data = &$this->getData();
                foreach ( $newData as $key => $value ) {
                        if ( !array_key_exists( $key, $data ) || $data[$key] !== $value ) {
                                $data[$key] = $value;
                                $this->dataDirty = true;
                                $this->logger->debug(
                                        'SessionBackend "{session}" data dirty due to addData(): {callers}',
                                        [
                                                'session' => $this->id,
                                                'callers' => wfGetAllCallers( 5 ),
                                ] );
                        }
                }
        }

        /**
         * Mark data as dirty
         * @private For use by \MediaWiki\Session\Session only.
         */
        public function dirty() {
                $this->dataDirty = true;
                $this->logger->debug(
                        'SessionBackend "{session}" data dirty due to dirty(): {callers}',
                        [
                                'session' => $this->id,
                                'callers' => wfGetAllCallers( 5 ),
                ] );
        }

        /**
         * Renew the session by resaving everything
         *
         * Resets the TTL in the backend store if the session is near expiring, and
         * re-persists the session to any active WebRequests if persistent.
         */
        public function renew() {
                if ( time() + $this->lifetime / 2 > $this->expires ) {
                        $this->metaDirty = true;
                        $this->logger->debug(
                                'SessionBackend "{callers}" metadata dirty for renew(): {callers}',
                                [
                                        'session' => $this->id,
                                        'callers' => wfGetAllCallers( 5 ),
                        ] );
                        if ( $this->persist ) {
                                $this->forcePersist = true;
                                $this->logger->debug(
                                        'SessionBackend "{session}" force-persist for renew(): {callers}',
                                        [
                                                'session' => $this->id,
                                                'callers' => wfGetAllCallers( 5 ),
                                ] );
                        }
                }
                $this->autosave();
        }

        /**
         * Delay automatic saving while multiple updates are being made
         *
         * Calls to save() will not be delayed.
         *
         * @return \Wikimedia\ScopedCallback When this goes out of scope, a save will be triggered
         */
        public function delaySave() {
                $this->delaySave++;
                return new \Wikimedia\ScopedCallback( function () {
                        if ( --$this->delaySave <= 0 ) {
                                $this->delaySave = 0;
                                $this->save();
                        }
                } );
        }

        /**
         * Save the session, unless delayed
         * @see SessionBackend::save()
         */
        private function autosave() {
                if ( $this->delaySave <= 0 ) {
                        $this->save();
                }
        }

        /**
         * Save the session
         *
         * Update both the backend data and the associated WebRequest(s) to
         * reflect the state of the the SessionBackend. This might include
         * persisting or unpersisting the session.
         *
         * @param bool $closing Whether the session is being closed
         */
        public function save( $closing = false ) {
                $anon = $this->user->isAnon();

                if ( !$anon && $this->provider->getManager()->isUserSessionPrevented( $this->user->getName() ) ) {
                        $this->logger->debug(
                                'SessionBackend "{session}" not saving, user {user} was ' .
                                'passed to SessionManager::preventSessionsForUser',
                                [
                                        'session' => $this->id,
                                        'user' => $this->user,
                        ] );
                        return;
                }

                // Ensure the user has a token
                // @codeCoverageIgnoreStart
                if ( !$anon && !$this->user->getToken( false ) ) {
                        $this->logger->debug(
                                'SessionBackend "{session}" creating token for user {user} on save',
                                [
                                        'session' => $this->id,
                                        'user' => $this->user,
                        ] );
                        $this->user->setToken();
                        if ( !wfReadOnly() ) {
                                // Promise that the token set here will be valid; save it at end of request
                                $user = $this->user;
                                \DeferredUpdates::addCallableUpdate( function () use ( $user ) {
                                        $user->saveSettings();
                                } );
                        }
                        $this->metaDirty = true;
                }
                // @codeCoverageIgnoreEnd

                if ( !$this->metaDirty && !$this->dataDirty &&
                        $this->dataHash !== md5( serialize( $this->data ) )
                ) {
                        $this->logger->debug(
                                'SessionBackend "{session}" data dirty due to hash mismatch, {expected} !== {got}',
                                [
                                        'session' => $this->id,
                                        'expected' => $this->dataHash,
                                        'got' => md5( serialize( $this->data ) ),
                        ] );
                        $this->dataDirty = true;
                }

                if ( !$this->metaDirty && !$this->dataDirty && !$this->forcePersist ) {
                        return;
                }

                $this->logger->debug(
                        'SessionBackend "{session}" save: dataDirty={dataDirty} ' .
                        'metaDirty={metaDirty} forcePersist={forcePersist}',
                        [
                                'session' => $this->id,
                                'dataDirty' => (int)$this->dataDirty,
                                'metaDirty' => (int)$this->metaDirty,
                                'forcePersist' => (int)$this->forcePersist,
                ] );

                // Persist or unpersist to the provider, if necessary
                if ( $this->metaDirty || $this->forcePersist ) {
                        if ( $this->persist ) {
                                foreach ( $this->requests as $request ) {
                                        $request->setSessionId( $this->getSessionId() );
                                        $this->provider->persistSession( $this, $request );
                                }
                                if ( !$closing ) {
                                        $this->checkPHPSession();
                                }
                        } else {
                                foreach ( $this->requests as $request ) {
                                        if ( $request->getSessionId() === $this->id ) {
                                                $this->provider->unpersistSession( $request );
                                        }
                                }
                        }
                }

                $this->forcePersist = false;

                if ( !$this->metaDirty && !$this->dataDirty ) {
                        return;
                }

                // Save session data to store, if necessary
                $metadata = $origMetadata = [
                        'provider' => (string)$this->provider,
                        'providerMetadata' => $this->providerMetadata,
                        'userId' => $anon ? 0 : $this->user->getId(),
                        'userName' => User::isValidUserName( $this->user->getName() ) ? $this->user->getName() : null,
                        'userToken' => $anon ? null : $this->user->getToken(),
                        'remember' => !$anon && $this->remember,
                        'forceHTTPS' => $this->forceHTTPS,
                        'expires' => time() + $this->lifetime,
                        'loggedOut' => $this->loggedOut,
                        'persisted' => $this->persist,
                ];

                \Hooks::run( 'SessionMetadata', [ $this, &$metadata, $this->requests ] );

                foreach ( $origMetadata as $k => $v ) {
                        if ( $metadata[$k] !== $v ) {
                                throw new \UnexpectedValueException( "SessionMetadata hook changed metadata key \"$k\"" );
                        }
                }

                $flags = $this->persist ? 0 : CachedBagOStuff::WRITE_CACHE_ONLY;
                $flags |= CachedBagOStuff::WRITE_SYNC; // write to all datacenters
                $this->store->set(
                        wfMemcKey( 'MWSession', (string)$this->id ),
                        [
                                'data' => $this->data,
                                'metadata' => $metadata,
                        ],
                        $metadata['expires'],
                        $flags
                );

                $this->metaDirty = false;
                $this->dataDirty = false;
                $this->dataHash = md5( serialize( $this->data ) );
                $this->expires = $metadata['expires'];
        }

        /**
         * For backwards compatibility, open the PHP session when the global
         * session is persisted
         */
        private function checkPHPSession() {
                if ( !$this->checkPHPSessionRecursionGuard ) {
                        $this->checkPHPSessionRecursionGuard = true;
                        $reset = new \Wikimedia\ScopedCallback( function () {
                                $this->checkPHPSessionRecursionGuard = false;
                        } );

                        if ( $this->usePhpSessionHandling && session_id() === '' && PHPSessionHandler::isEnabled() &&
                                SessionManager::getGlobalSession()->getId() === (string)$this->id
                        ) {
                                $this->logger->debug(
                                        'SessionBackend "{session}" Taking over PHP session',
                                        [
                                                'session' => $this->id,
                                ] );
                                session_id( (string)$this->id );
                                \MediaWiki\quietCall( 'session_start' );
                        }
                }
        }

}