Merge "Special:Upload should not crash on failing previews"

[mediawiki.git] / includes / api / ApiMain.php

<?php
/**
 *
 *
 * Created on Sep 4, 2006
 *
 * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
 *
 * 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
 * @defgroup API API
 */

use MediaWiki\Logger\LoggerFactory;

/**
 * This is the main API class, used for both external and internal processing.
 * When executed, it will create the requested formatter object,
 * instantiate and execute an object associated with the needed action,
 * and use formatter to print results.
 * In case of an exception, an error message will be printed using the same formatter.
 *
 * To use API from another application, run it using FauxRequest object, in which
 * case any internal exceptions will not be handled but passed up to the caller.
 * After successful execution, use getResult() for the resulting data.
 *
 * @ingroup API
 */
class ApiMain extends ApiBase {
        /**
         * When no format parameter is given, this format will be used
         */
        const API_DEFAULT_FORMAT = 'jsonfm';

        /**
         * When no uselang parameter is given, this language will be used
         */
        const API_DEFAULT_USELANG = 'user';

        /**
         * List of available modules: action name => module class
         */
        private static $Modules = [
                'login' => 'ApiLogin',
                'clientlogin' => 'ApiClientLogin',
                'logout' => 'ApiLogout',
                'createaccount' => 'ApiAMCreateAccount',
                'linkaccount' => 'ApiLinkAccount',
                'unlinkaccount' => 'ApiRemoveAuthenticationData',
                'changeauthenticationdata' => 'ApiChangeAuthenticationData',
                'removeauthenticationdata' => 'ApiRemoveAuthenticationData',
                'resetpassword' => 'ApiResetPassword',
                'query' => 'ApiQuery',
                'expandtemplates' => 'ApiExpandTemplates',
                'parse' => 'ApiParse',
                'stashedit' => 'ApiStashEdit',
                'opensearch' => 'ApiOpenSearch',
                'feedcontributions' => 'ApiFeedContributions',
                'feedrecentchanges' => 'ApiFeedRecentChanges',
                'feedwatchlist' => 'ApiFeedWatchlist',
                'help' => 'ApiHelp',
                'paraminfo' => 'ApiParamInfo',
                'rsd' => 'ApiRsd',
                'compare' => 'ApiComparePages',
                'tokens' => 'ApiTokens',
                'checktoken' => 'ApiCheckToken',
                'cspreport' => 'ApiCSPReport',
                'validatepassword' => 'ApiValidatePassword',

                // Write modules
                'purge' => 'ApiPurge',
                'setnotificationtimestamp' => 'ApiSetNotificationTimestamp',
                'rollback' => 'ApiRollback',
                'delete' => 'ApiDelete',
                'undelete' => 'ApiUndelete',
                'protect' => 'ApiProtect',
                'block' => 'ApiBlock',
                'unblock' => 'ApiUnblock',
                'move' => 'ApiMove',
                'edit' => 'ApiEditPage',
                'upload' => 'ApiUpload',
                'filerevert' => 'ApiFileRevert',
                'emailuser' => 'ApiEmailUser',
                'watch' => 'ApiWatch',
                'patrol' => 'ApiPatrol',
                'import' => 'ApiImport',
                'clearhasmsg' => 'ApiClearHasMsg',
                'userrights' => 'ApiUserrights',
                'options' => 'ApiOptions',
                'imagerotate' => 'ApiImageRotate',
                'revisiondelete' => 'ApiRevisionDelete',
                'managetags' => 'ApiManageTags',
                'tag' => 'ApiTag',
                'mergehistory' => 'ApiMergeHistory',
                'setpagelanguage' => 'ApiSetPageLanguage',
        ];

        /**
         * List of available formats: format name => format class
         */
        private static $Formats = [
                'json' => 'ApiFormatJson',
                'jsonfm' => 'ApiFormatJson',
                'php' => 'ApiFormatPhp',
                'phpfm' => 'ApiFormatPhp',
                'xml' => 'ApiFormatXml',
                'xmlfm' => 'ApiFormatXml',
                'rawfm' => 'ApiFormatJson',
                'none' => 'ApiFormatNone',
        ];

        // @codingStandardsIgnoreStart String contenation on "msg" not allowed to break long line
        /**
         * List of user roles that are specifically relevant to the API.
         * [ 'right' => [ 'msg'    => 'Some message with a $1',
         *                'params' => [ $someVarToSubst ] ],
         * ];
         */
        private static $mRights = [
                'writeapi' => [
                        'msg' => 'right-writeapi',
                        'params' => []
                ],
                'apihighlimits' => [
                        'msg' => 'api-help-right-apihighlimits',
                        'params' => [ ApiBase::LIMIT_SML2, ApiBase::LIMIT_BIG2 ]
                ]
        ];
        // @codingStandardsIgnoreEnd

        /**
         * @var ApiFormatBase
         */
        private $mPrinter;

        private $mModuleMgr, $mResult, $mErrorFormatter = null;
        /** @var ApiContinuationManager|null */
        private $mContinuationManager;
        private $mAction;
        private $mEnableWrite;
        private $mInternalMode, $mSquidMaxage;
        /** @var ApiBase */
        private $mModule;

        private $mCacheMode = 'private';
        private $mCacheControl = [];
        private $mParamsUsed = [];

        /** @var bool|null Cached return value from self::lacksSameOriginSecurity() */
        private $lacksSameOriginSecurity = null;

        /**
         * Constructs an instance of ApiMain that utilizes the module and format specified by $request.
         *
         * @param IContextSource|WebRequest $context If this is an instance of
         *    FauxRequest, errors are thrown and no printing occurs
         * @param bool $enableWrite Should be set to true if the api may modify data
         */
        public function __construct( $context = null, $enableWrite = false ) {
                if ( $context === null ) {
                        $context = RequestContext::getMain();
                } elseif ( $context instanceof WebRequest ) {
                        // BC for pre-1.19
                        $request = $context;
                        $context = RequestContext::getMain();
                }
                // We set a derivative context so we can change stuff later
                $this->setContext( new DerivativeContext( $context ) );

                if ( isset( $request ) ) {
                        $this->getContext()->setRequest( $request );
                } else {
                        $request = $this->getRequest();
                }

                $this->mInternalMode = ( $request instanceof FauxRequest );

                // Special handling for the main module: $parent === $this
                parent::__construct( $this, $this->mInternalMode ? 'main_int' : 'main' );

                $config = $this->getConfig();

                if ( !$this->mInternalMode ) {
                        // Log if a request with a non-whitelisted Origin header is seen
                        // with session cookies.
                        $originHeader = $request->getHeader( 'Origin' );
                        if ( $originHeader === false ) {
                                $origins = [];
                        } else {
                                $originHeader = trim( $originHeader );
                                $origins = preg_split( '/\s+/', $originHeader );
                        }
                        $sessionCookies = array_intersect(
                                array_keys( $_COOKIE ),
                                MediaWiki\Session\SessionManager::singleton()->getVaryCookies()
                        );
                        if ( $origins && $sessionCookies && (
                                count( $origins ) !== 1 || !self::matchOrigin(
                                        $origins[0],
                                        $config->get( 'CrossSiteAJAXdomains' ),
                                        $config->get( 'CrossSiteAJAXdomainExceptions' )
                                )
                        ) ) {
                                LoggerFactory::getInstance( 'cors' )->warning(
                                        'Non-whitelisted CORS request with session cookies', [
                                                'origin' => $originHeader,
                                                'cookies' => $sessionCookies,
                                                'ip' => $request->getIP(),
                                                'userAgent' => $this->getUserAgent(),
                                                'wiki' => wfWikiID(),
                                        ]
                                );
                        }

                        // If we're in a mode that breaks the same-origin policy, strip
                        // user credentials for security.
                        if ( $this->lacksSameOriginSecurity() ) {
                                global $wgUser;
                                wfDebug( "API: stripping user credentials when the same-origin policy is not applied\n" );
                                $wgUser = new User();
                                $this->getContext()->setUser( $wgUser );
                        }
                }

                $this->mResult = new ApiResult( $this->getConfig()->get( 'APIMaxResultSize' ) );

                // Setup uselang. This doesn't use $this->getParameter()
                // because we're not ready to handle errors yet.
                $uselang = $request->getVal( 'uselang', self::API_DEFAULT_USELANG );
                if ( $uselang === 'user' ) {
                        // Assume the parent context is going to return the user language
                        // for uselang=user (see T85635).
                } else {
                        if ( $uselang === 'content' ) {
                                global $wgContLang;
                                $uselang = $wgContLang->getCode();
                        }
                        $code = RequestContext::sanitizeLangCode( $uselang );
                        $this->getContext()->setLanguage( $code );
                        if ( !$this->mInternalMode ) {
                                global $wgLang;
                                $wgLang = $this->getContext()->getLanguage();
                                RequestContext::getMain()->setLanguage( $wgLang );
                        }
                }

                // Set up the error formatter. This doesn't use $this->getParameter()
                // because we're not ready to handle errors yet.
                $errorFormat = $request->getVal( 'errorformat', 'bc' );
                $errorLangCode = $request->getVal( 'errorlang', 'uselang' );
                $errorsUseDB = $request->getCheck( 'errorsuselocal' );
                if ( in_array( $errorFormat, [ 'plaintext', 'wikitext', 'html', 'raw', 'none' ], true ) ) {
                        if ( $errorLangCode === 'uselang' ) {
                                $errorLang = $this->getLanguage();
                        } elseif ( $errorLangCode === 'content' ) {
                                global $wgContLang;
                                $errorLang = $wgContLang;
                        } else {
                                $errorLangCode = RequestContext::sanitizeLangCode( $errorLangCode );
                                $errorLang = Language::factory( $errorLangCode );
                        }
                        $this->mErrorFormatter = new ApiErrorFormatter(
                                $this->mResult, $errorLang, $errorFormat, $errorsUseDB
                        );
                } else {
                        $this->mErrorFormatter = new ApiErrorFormatter_BackCompat( $this->mResult );
                }
                $this->mResult->setErrorFormatter( $this->getErrorFormatter() );

                $this->mModuleMgr = new ApiModuleManager( $this );
                $this->mModuleMgr->addModules( self::$Modules, 'action' );
                $this->mModuleMgr->addModules( $config->get( 'APIModules' ), 'action' );
                $this->mModuleMgr->addModules( self::$Formats, 'format' );
                $this->mModuleMgr->addModules( $config->get( 'APIFormatModules' ), 'format' );

                Hooks::run( 'ApiMain::moduleManager', [ $this->mModuleMgr ] );

                $this->mContinuationManager = null;
                $this->mEnableWrite = $enableWrite;

                $this->mSquidMaxage = -1; // flag for executeActionWithErrorHandling()
                $this->mCommit = false;
        }

        /**
         * Return true if the API was started by other PHP code using FauxRequest
         * @return bool
         */
        public function isInternalMode() {
                return $this->mInternalMode;
        }

        /**
         * Get the ApiResult object associated with current request
         *
         * @return ApiResult
         */
        public function getResult() {
                return $this->mResult;
        }

        /**
         * Get the security flag for the current request
         * @return bool
         */
        public function lacksSameOriginSecurity() {
                if ( $this->lacksSameOriginSecurity !== null ) {
                        return $this->lacksSameOriginSecurity;
                }

                $request = $this->getRequest();

                // JSONP mode
                if ( $request->getVal( 'callback' ) !== null ) {
                        $this->lacksSameOriginSecurity = true;
                        return true;
                }

                // Anonymous CORS
                if ( $request->getVal( 'origin' ) === '*' ) {
                        $this->lacksSameOriginSecurity = true;
                        return true;
                }

                // Header to be used from XMLHTTPRequest when the request might
                // otherwise be used for XSS.
                if ( $request->getHeader( 'Treat-as-Untrusted' ) !== false ) {
                        $this->lacksSameOriginSecurity = true;
                        return true;
                }

                // Allow extensions to override.
                $this->lacksSameOriginSecurity = !Hooks::run( 'RequestHasSameOriginSecurity', [ $request ] );
                return $this->lacksSameOriginSecurity;
        }

        /**
         * Get the ApiErrorFormatter object associated with current request
         * @return ApiErrorFormatter
         */
        public function getErrorFormatter() {
                return $this->mErrorFormatter;
        }

        /**
         * Get the continuation manager
         * @return ApiContinuationManager|null
         */
        public function getContinuationManager() {
                return $this->mContinuationManager;
        }

        /**
         * Set the continuation manager
         * @param ApiContinuationManager|null
         */
        public function setContinuationManager( $manager ) {
                if ( $manager !== null ) {
                        if ( !$manager instanceof ApiContinuationManager ) {
                                throw new InvalidArgumentException( __METHOD__ . ': Was passed ' .
                                        is_object( $manager ) ? get_class( $manager ) : gettype( $manager )
                                );
                        }
                        if ( $this->mContinuationManager !== null ) {
                                throw new UnexpectedValueException(
                                        __METHOD__ . ': tried to set manager from ' . $manager->getSource() .
                                        ' when a manager is already set from ' . $this->mContinuationManager->getSource()
                                );
                        }
                }
                $this->mContinuationManager = $manager;
        }

        /**
         * Get the API module object. Only works after executeAction()
         *
         * @return ApiBase
         */
        public function getModule() {
                return $this->mModule;
        }

        /**
         * Get the result formatter object. Only works after setupExecuteAction()
         *
         * @return ApiFormatBase
         */
        public function getPrinter() {
                return $this->mPrinter;
        }

        /**
         * Set how long the response should be cached.
         *
         * @param int $maxage
         */
        public function setCacheMaxAge( $maxage ) {
                $this->setCacheControl( [
                        'max-age' => $maxage,
                        's-maxage' => $maxage
                ] );
        }

        /**
         * Set the type of caching headers which will be sent.
         *
         * @param string $mode One of:
         *    - 'public':     Cache this object in public caches, if the maxage or smaxage
         *         parameter is set, or if setCacheMaxAge() was called. If a maximum age is
         *         not provided by any of these means, the object will be private.
         *    - 'private':    Cache this object only in private client-side caches.
         *    - 'anon-public-user-private': Make this object cacheable for logged-out
         *         users, but private for logged-in users. IMPORTANT: If this is set, it must be
         *         set consistently for a given URL, it cannot be set differently depending on
         *         things like the contents of the database, or whether the user is logged in.
         *
         *  If the wiki does not allow anonymous users to read it, the mode set here
         *  will be ignored, and private caching headers will always be sent. In other words,
         *  the "public" mode is equivalent to saying that the data sent is as public as a page
         *  view.
         *
         *  For user-dependent data, the private mode should generally be used. The
         *  anon-public-user-private mode should only be used where there is a particularly
         *  good performance reason for caching the anonymous response, but where the
         *  response to logged-in users may differ, or may contain private data.
         *
         *  If this function is never called, then the default will be the private mode.
         */
        public function setCacheMode( $mode ) {
                if ( !in_array( $mode, [ 'private', 'public', 'anon-public-user-private' ] ) ) {
                        wfDebug( __METHOD__ . ": unrecognised cache mode \"$mode\"\n" );

                        // Ignore for forwards-compatibility
                        return;
                }

                if ( !User::isEveryoneAllowed( 'read' ) ) {
                        // Private wiki, only private headers
                        if ( $mode !== 'private' ) {
                                wfDebug( __METHOD__ . ": ignoring request for $mode cache mode, private wiki\n" );

                                return;
                        }
                }

                if ( $mode === 'public' && $this->getParameter( 'uselang' ) === 'user' ) {
                        // User language is used for i18n, so we don't want to publicly
                        // cache. Anons are ok, because if they have non-default language
                        // then there's an appropriate Vary header set by whatever set
                        // their non-default language.
                        wfDebug( __METHOD__ . ": downgrading cache mode 'public' to " .
                                "'anon-public-user-private' due to uselang=user\n" );
                        $mode = 'anon-public-user-private';
                }

                wfDebug( __METHOD__ . ": setting cache mode $mode\n" );
                $this->mCacheMode = $mode;
        }

        /**
         * Set directives (key/value pairs) for the Cache-Control header.
         * Boolean values will be formatted as such, by including or omitting
         * without an equals sign.
         *
         * Cache control values set here will only be used if the cache mode is not
         * private, see setCacheMode().
         *
         * @param array $directives
         */
        public function setCacheControl( $directives ) {
                $this->mCacheControl = $directives + $this->mCacheControl;
        }

        /**
         * Create an instance of an output formatter by its name
         *
         * @param string $format
         *
         * @return ApiFormatBase
         */
        public function createPrinterByName( $format ) {
                $printer = $this->mModuleMgr->getModule( $format, 'format' );
                if ( $printer === null ) {
                        $this->dieWithError(
                                [ 'apierror-unknownformat', wfEscapeWikiText( $format ) ], 'unknown_format'
                        );
                }

                return $printer;
        }

        /**
         * Execute api request. Any errors will be handled if the API was called by the remote client.
         */
        public function execute() {
                if ( $this->mInternalMode ) {
                        $this->executeAction();
                } else {
                        $this->executeActionWithErrorHandling();
                }
        }

        /**
         * Execute an action, and in case of an error, erase whatever partial results
         * have been accumulated, and replace it with an error message and a help screen.
         */
        protected function executeActionWithErrorHandling() {
                // Verify the CORS header before executing the action
                if ( !$this->handleCORS() ) {
                        // handleCORS() has sent a 403, abort
                        return;
                }

                // Exit here if the request method was OPTIONS
                // (assume there will be a followup GET or POST)
                if ( $this->getRequest()->getMethod() === 'OPTIONS' ) {
                        return;
                }

                // In case an error occurs during data output,
                // clear the output buffer and print just the error information
                $obLevel = ob_get_level();
                ob_start();

                $t = microtime( true );
                $isError = false;
                try {
                        $this->executeAction();
                        $runTime = microtime( true ) - $t;
                        $this->logRequest( $runTime );
                        if ( $this->mModule->isWriteMode() && $this->getRequest()->wasPosted() ) {
                                $this->getStats()->timing(
                                        'api.' . $this->mModule->getModuleName() . '.executeTiming', 1000 * $runTime
                                );
                        }
                } catch ( Exception $e ) {
                        $this->handleException( $e );
                        $this->logRequest( microtime( true ) - $t, $e );
                        $isError = true;
                }

                // Commit DBs and send any related cookies and headers
                MediaWiki::preOutputCommit( $this->getContext() );

                // Send cache headers after any code which might generate an error, to
                // avoid sending public cache headers for errors.
                $this->sendCacheHeaders( $isError );

                // Executing the action might have already messed with the output
                // buffers.
                while ( ob_get_level() > $obLevel ) {
                        ob_end_flush();
                }
        }

        /**
         * Handle an exception as an API response
         *
         * @since 1.23
         * @param Exception $e
         */
        protected function handleException( Exception $e ) {
                // Bug 63145: Rollback any open database transactions
                if ( !( $e instanceof ApiUsageException || $e instanceof UsageException ) ) {
                        // UsageExceptions are intentional, so don't rollback if that's the case
                        try {
                                MWExceptionHandler::rollbackMasterChangesAndLog( $e );
                        } catch ( DBError $e2 ) {
                                // Rollback threw an exception too. Log it, but don't interrupt
                                // our regularly scheduled exception handling.
                                MWExceptionHandler::logException( $e2 );
                        }
                }

                // Allow extra cleanup and logging
                Hooks::run( 'ApiMain::onException', [ $this, $e ] );

                // Log it
                if ( !( $e instanceof ApiUsageException || $e instanceof UsageException ) ) {
                        MWExceptionHandler::logException( $e );
                }

                // Handle any kind of exception by outputting properly formatted error message.
                // If this fails, an unhandled exception should be thrown so that global error
                // handler will process and log it.

                $errCodes = $this->substituteResultWithError( $e );

                // Error results should not be cached
                $this->setCacheMode( 'private' );

                $response = $this->getRequest()->response();
                $headerStr = 'MediaWiki-API-Error: ' . join( ', ', $errCodes );
                $response->header( $headerStr );

                // Reset and print just the error message
                ob_clean();

                // Printer may not be initialized if the extractRequestParams() fails for the main module
                $this->createErrorPrinter();

                $failed = false;
                try {
                        $this->printResult( $e->getCode() );
                } catch ( ApiUsageException $ex ) {
                        // The error printer itself is failing. Try suppressing its request
                        // parameters and redo.
                        $failed = true;
                        $this->addWarning( 'apiwarn-errorprinterfailed' );
                        foreach ( $ex->getStatusValue()->getErrors() as $error ) {
                                try {
                                        $this->mPrinter->addWarning( $error );
                                } catch ( Exception $ex2 ) {
                                        // WTF?
                                        $this->addWarning( $error );
                                }
                        }
                } catch ( UsageException $ex ) {
                        // The error printer itself is failing. Try suppressing its request
                        // parameters and redo.
                        $failed = true;
                        $this->addWarning(
                                [ 'apiwarn-errorprinterfailed-ex', $ex->getMessage() ], 'errorprinterfailed'
                        );
                }
                if ( $failed ) {
                        $this->mPrinter = null;
                        $this->createErrorPrinter();
                        $this->mPrinter->forceDefaultParams();
                        if ( $e->getCode() ) {
                                $response->statusHeader( 200 ); // Reset in case the fallback doesn't want a non-200
                        }
                        $this->printResult( $e->getCode() );
                }
        }

        /**
         * Handle an exception from the ApiBeforeMain hook.
         *
         * This tries to print the exception as an API response, to be more
         * friendly to clients. If it fails, it will rethrow the exception.
         *
         * @since 1.23
         * @param Exception $e
         * @throws Exception
         */
        public static function handleApiBeforeMainException( Exception $e ) {
                ob_start();

                try {
                        $main = new self( RequestContext::getMain(), false );
                        $main->handleException( $e );
                        $main->logRequest( 0, $e );
                } catch ( Exception $e2 ) {
                        // Nope, even that didn't work. Punt.
                        throw $e;
                }

                // Reset cache headers
                $main->sendCacheHeaders( true );

                ob_end_flush();
        }

        /**
         * Check the &origin= query parameter against the Origin: HTTP header and respond appropriately.
         *
         * If no origin parameter is present, nothing happens.
         * If an origin parameter is present but doesn't match the Origin header, a 403 status code
         * is set and false is returned.
         * If the parameter and the header do match, the header is checked against $wgCrossSiteAJAXdomains
         * and $wgCrossSiteAJAXdomainExceptions, and if the origin qualifies, the appropriate CORS
         * headers are set.
         * https://www.w3.org/TR/cors/#resource-requests
         * https://www.w3.org/TR/cors/#resource-preflight-requests
         *
         * @return bool False if the caller should abort (403 case), true otherwise (all other cases)
         */
        protected function handleCORS() {
                $originParam = $this->getParameter( 'origin' ); // defaults to null
                if ( $originParam === null ) {
                        // No origin parameter, nothing to do
                        return true;
                }

                $request = $this->getRequest();
                $response = $request->response();

                $matchOrigin = false;
                $allowTiming = false;
                $varyOrigin = true;

                if ( $originParam === '*' ) {
                        // Request for anonymous CORS
                        $matchOrigin = true;
                        $allowOrigin = '*';
                        $allowCredentials = 'false';
                        $varyOrigin = false; // No need to vary
                } else {
                        // Non-anonymous CORS, check we allow the domain

                        // Origin: header is a space-separated list of origins, check all of them
                        $originHeader = $request->getHeader( 'Origin' );
                        if ( $originHeader === false ) {
                                $origins = [];
                        } else {
                                $originHeader = trim( $originHeader );
                                $origins = preg_split( '/\s+/', $originHeader );
                        }

                        if ( !in_array( $originParam, $origins ) ) {
                                // origin parameter set but incorrect
                                // Send a 403 response
                                $response->statusHeader( 403 );
                                $response->header( 'Cache-Control: no-cache' );
                                echo "'origin' parameter does not match Origin header\n";

                                return false;
                        }

                        $config = $this->getConfig();
                        $matchOrigin = count( $origins ) === 1 && self::matchOrigin(
                                $originParam,
                                $config->get( 'CrossSiteAJAXdomains' ),
                                $config->get( 'CrossSiteAJAXdomainExceptions' )
                        );

                        $allowOrigin = $originHeader;
                        $allowCredentials = 'true';
                        $allowTiming = $originHeader;
                }

                if ( $matchOrigin ) {
                        $requestedMethod = $request->getHeader( 'Access-Control-Request-Method' );
                        $preflight = $request->getMethod() === 'OPTIONS' && $requestedMethod !== false;
                        if ( $preflight ) {
                                // This is a CORS preflight request
                                if ( $requestedMethod !== 'POST' && $requestedMethod !== 'GET' ) {
                                        // If method is not a case-sensitive match, do not set any additional headers and terminate.
                                        return true;
                                }
                                // We allow the actual request to send the following headers
                                $requestedHeaders = $request->getHeader( 'Access-Control-Request-Headers' );
                                if ( $requestedHeaders !== false ) {
                                        if ( !self::matchRequestedHeaders( $requestedHeaders ) ) {
                                                return true;
                                        }
                                        $response->header( 'Access-Control-Allow-Headers: ' . $requestedHeaders );
                                }

                                // We only allow the actual request to be GET or POST
                                $response->header( 'Access-Control-Allow-Methods: POST, GET' );
                        }

                        $response->header( "Access-Control-Allow-Origin: $allowOrigin" );
                        $response->header( "Access-Control-Allow-Credentials: $allowCredentials" );
                        // https://www.w3.org/TR/resource-timing/#timing-allow-origin
                        if ( $allowTiming !== false ) {
                                $response->header( "Timing-Allow-Origin: $allowTiming" );
                        }

                        if ( !$preflight ) {
                                $response->header(
                                        'Access-Control-Expose-Headers: MediaWiki-API-Error, Retry-After, X-Database-Lag'
                                );
                        }
                }

                if ( $varyOrigin ) {
                        $this->getOutput()->addVaryHeader( 'Origin' );
                }

                return true;
        }

        /**
         * Attempt to match an Origin header against a set of rules and a set of exceptions
         * @param string $value Origin header
         * @param array $rules Set of wildcard rules
         * @param array $exceptions Set of wildcard rules
         * @return bool True if $value matches a rule in $rules and doesn't match
         *    any rules in $exceptions, false otherwise
         */
        protected static function matchOrigin( $value, $rules, $exceptions ) {
                foreach ( $rules as $rule ) {
                        if ( preg_match( self::wildcardToRegex( $rule ), $value ) ) {
                                // Rule matches, check exceptions
                                foreach ( $exceptions as $exc ) {
                                        if ( preg_match( self::wildcardToRegex( $exc ), $value ) ) {
                                                return false;
                                        }
                                }

                                return true;
                        }
                }

                return false;
        }

        /**
         * Attempt to validate the value of Access-Control-Request-Headers against a list
         * of headers that we allow the follow up request to send.
         *
         * @param string $requestedHeaders Comma seperated list of HTTP headers
         * @return bool True if all requested headers are in the list of allowed headers
         */
        protected static function matchRequestedHeaders( $requestedHeaders ) {
                if ( trim( $requestedHeaders ) === '' ) {
                        return true;
                }
                $requestedHeaders = explode( ',', $requestedHeaders );
                $allowedAuthorHeaders = array_flip( [
                        /* simple headers (see spec) */
                        'accept',
                        'accept-language',
                        'content-language',
                        'content-type',
                        /* non-authorable headers in XHR, which are however requested by some UAs */
                        'accept-encoding',
                        'dnt',
                        'origin',
                        /* MediaWiki whitelist */
                        'api-user-agent',
                ] );
                foreach ( $requestedHeaders as $rHeader ) {
                        $rHeader = strtolower( trim( $rHeader ) );
                        if ( !isset( $allowedAuthorHeaders[$rHeader] ) ) {
                                wfDebugLog( 'api', 'CORS preflight failed on requested header: ' . $rHeader );
                                return false;
                        }
                }
                return true;
        }

        /**
         * Helper function to convert wildcard string into a regex
         * '*' => '.*?'
         * '?' => '.'
         *
         * @param string $wildcard String with wildcards
         * @return string Regular expression
         */
        protected static function wildcardToRegex( $wildcard ) {
                $wildcard = preg_quote( $wildcard, '/' );
                $wildcard = str_replace(
                        [ '\*', '\?' ],
                        [ '.*?', '.' ],
                        $wildcard
                );

                return "/^https?:\/\/$wildcard$/";
        }

        /**
         * Send caching headers
         * @param bool $isError Whether an error response is being output
         * @since 1.26 added $isError parameter
         */
        protected function sendCacheHeaders( $isError ) {
                $response = $this->getRequest()->response();
                $out = $this->getOutput();

                $out->addVaryHeader( 'Treat-as-Untrusted' );

                $config = $this->getConfig();

                if ( $config->get( 'VaryOnXFP' ) ) {
                        $out->addVaryHeader( 'X-Forwarded-Proto' );
                }

                if ( !$isError && $this->mModule &&
                        ( $this->getRequest()->getMethod() === 'GET' || $this->getRequest()->getMethod() === 'HEAD' )
                ) {
                        $etag = $this->mModule->getConditionalRequestData( 'etag' );
                        if ( $etag !== null ) {
                                $response->header( "ETag: $etag" );
                        }
                        $lastMod = $this->mModule->getConditionalRequestData( 'last-modified' );
                        if ( $lastMod !== null ) {
                                $response->header( 'Last-Modified: ' . wfTimestamp( TS_RFC2822, $lastMod ) );
                        }
                }

                // The logic should be:
                // $this->mCacheControl['max-age'] is set?
                //    Use it, the module knows better than our guess.
                // !$this->mModule || $this->mModule->isWriteMode(), and mCacheMode is private?
                //    Use 0 because we can guess caching is probably the wrong thing to do.
                // Use $this->getParameter( 'maxage' ), which already defaults to 0.
                $maxage = 0;
                if ( isset( $this->mCacheControl['max-age'] ) ) {
                        $maxage = $this->mCacheControl['max-age'];
                } elseif ( ( $this->mModule && !$this->mModule->isWriteMode() ) ||
                        $this->mCacheMode !== 'private'
                ) {
                        $maxage = $this->getParameter( 'maxage' );
                }
                $privateCache = 'private, must-revalidate, max-age=' . $maxage;

                if ( $this->mCacheMode == 'private' ) {
                        $response->header( "Cache-Control: $privateCache" );
                        return;
                }

                $useKeyHeader = $config->get( 'UseKeyHeader' );
                if ( $this->mCacheMode == 'anon-public-user-private' ) {
                        $out->addVaryHeader( 'Cookie' );
                        $response->header( $out->getVaryHeader() );
                        if ( $useKeyHeader ) {
                                $response->header( $out->getKeyHeader() );
                                if ( $out->haveCacheVaryCookies() ) {
                                        // Logged in, mark this request private
                                        $response->header( "Cache-Control: $privateCache" );
                                        return;
                                }
                                // Logged out, send normal public headers below
                        } elseif ( MediaWiki\Session\SessionManager::getGlobalSession()->isPersistent() ) {
                                // Logged in or otherwise has session (e.g. anonymous users who have edited)
                                // Mark request private
                                $response->header( "Cache-Control: $privateCache" );

                                return;
                        } // else no Key and anonymous, send public headers below
                }

                // Send public headers
                $response->header( $out->getVaryHeader() );
                if ( $useKeyHeader ) {
                        $response->header( $out->getKeyHeader() );
                }

                // If nobody called setCacheMaxAge(), use the (s)maxage parameters
                if ( !isset( $this->mCacheControl['s-maxage'] ) ) {
                        $this->mCacheControl['s-maxage'] = $this->getParameter( 'smaxage' );
                }
                if ( !isset( $this->mCacheControl['max-age'] ) ) {
                        $this->mCacheControl['max-age'] = $this->getParameter( 'maxage' );
                }

                if ( !$this->mCacheControl['s-maxage'] && !$this->mCacheControl['max-age'] ) {
                        // Public cache not requested
                        // Sending a Vary header in this case is harmless, and protects us
                        // against conditional calls of setCacheMaxAge().
                        $response->header( "Cache-Control: $privateCache" );

                        return;
                }

                $this->mCacheControl['public'] = true;

                // Send an Expires header
                $maxAge = min( $this->mCacheControl['s-maxage'], $this->mCacheControl['max-age'] );
                $expiryUnixTime = ( $maxAge == 0 ? 1 : time() + $maxAge );
                $response->header( 'Expires: ' . wfTimestamp( TS_RFC2822, $expiryUnixTime ) );

                // Construct the Cache-Control header
                $ccHeader = '';
                $separator = '';
                foreach ( $this->mCacheControl as $name => $value ) {
                        if ( is_bool( $value ) ) {
                                if ( $value ) {
                                        $ccHeader .= $separator . $name;
                                        $separator = ', ';
                                }
                        } else {
                                $ccHeader .= $separator . "$name=$value";
                                $separator = ', ';
                        }
                }

                $response->header( "Cache-Control: $ccHeader" );
        }

        /**
         * Create the printer for error output
         */
        private function createErrorPrinter() {
                if ( !isset( $this->mPrinter ) ) {
                        $value = $this->getRequest()->getVal( 'format', self::API_DEFAULT_FORMAT );
                        if ( !$this->mModuleMgr->isDefined( $value, 'format' ) ) {
                                $value = self::API_DEFAULT_FORMAT;
                        }
                        $this->mPrinter = $this->createPrinterByName( $value );
                }

                // Printer may not be able to handle errors. This is particularly
                // likely if the module returns something for getCustomPrinter().
                if ( !$this->mPrinter->canPrintErrors() ) {
                        $this->mPrinter = $this->createPrinterByName( self::API_DEFAULT_FORMAT );
                }
        }

        /**
         * Create an error message for the given exception.
         *
         * If an ApiUsageException, errors/warnings will be extracted from the
         * embedded StatusValue.
         *
         * If a base UsageException, the getMessageArray() method will be used to
         * extract the code and English message for a single error (no warnings).
         *
         * Any other exception will be returned with a generic code and wrapper
         * text around the exception's (presumably English) message as a single
         * error (no warnings).
         *
         * @param Exception $e
         * @param string $type 'error' or 'warning'
         * @return ApiMessage[]
         * @since 1.27
         */
        protected function errorMessagesFromException( $e, $type = 'error' ) {
                $messages = [];
                if ( $e instanceof ApiUsageException ) {
                        foreach ( $e->getStatusValue()->getErrorsByType( $type ) as $error ) {
                                $messages[] = ApiMessage::create( $error );
                        }
                } elseif ( $type !== 'error' ) {
                        // None of the rest have any messages for non-error types
                } elseif ( $e instanceof UsageException ) {
                        // User entered incorrect parameters - generate error response
                        $data = $e->getMessageArray();
                        $code = $data['code'];
                        $info = $data['info'];
                        unset( $data['code'], $data['info'] );
                        $messages[] = new ApiRawMessage( [ '$1', $info ], $code, $data );
                } else {
                        // Something is seriously wrong
                        $config = $this->getConfig();
                        $code = 'internal_api_error_' . get_class( $e );
                        if ( ( $e instanceof DBQueryError ) && !$config->get( 'ShowSQLErrors' ) ) {
                                $params = [ 'apierror-databaseerror', WebRequest::getRequestId() ];
                        } else {
                                $params = [
                                        'apierror-exceptioncaught',
                                        WebRequest::getRequestId(),
                                        $e instanceof ILocalizedException
                                                ? $e->getMessageObject()
                                                : wfEscapeWikiText( $e->getMessage() )
                                ];
                        }
                        $messages[] = ApiMessage::create( $params, $code );
                }
                return $messages;
        }

        /**
         * Replace the result data with the information about an exception.
         * @param Exception $e
         * @return string[] Error codes
         */
        protected function substituteResultWithError( $e ) {
                $result = $this->getResult();
                $formatter = $this->getErrorFormatter();
                $config = $this->getConfig();
                $errorCodes = [];

                // Remember existing warnings and errors across the reset
                $errors = $result->getResultData( [ 'errors' ] );
                $warnings = $result->getResultData( [ 'warnings' ] );
                $result->reset();
                if ( $warnings !== null ) {
                        $result->addValue( null, 'warnings', $warnings, ApiResult::NO_SIZE_CHECK );
                }
                if ( $errors !== null ) {
                        $result->addValue( null, 'errors', $errors, ApiResult::NO_SIZE_CHECK );

                        // Collect the copied error codes for the return value
                        foreach ( $errors as $error ) {
                                if ( isset( $error['code'] ) ) {
                                        $errorCodes[$error['code']] = true;
                                }
                        }
                }

                // Add errors from the exception
                $modulePath = $e instanceof ApiUsageException ? $e->getModulePath() : null;
                foreach ( $this->errorMessagesFromException( $e, 'error' ) as $msg ) {
                        $errorCodes[$msg->getApiCode()] = true;
                        $formatter->addError( $modulePath, $msg );
                }
                foreach ( $this->errorMessagesFromException( $e, 'warning' ) as $msg ) {
                        $formatter->addWarning( $modulePath, $msg );
                }

                // Add additional data. Path depends on whether we're in BC mode or not.
                // Data depends on the type of exception.
                if ( $formatter instanceof ApiErrorFormatter_BackCompat ) {
                        $path = [ 'error' ];
                } else {
                        $path = null;
                }
                if ( $e instanceof ApiUsageException || $e instanceof UsageException ) {
                        $link = wfExpandUrl( wfScript( 'api' ) );
                        $result->addContentValue(
                                $path,
                                'docref',
                                $this->msg( 'api-usage-docref', $link )->inLanguage( $formatter->getLanguage() )->text()
                        );
                } else {
                        if ( $config->get( 'ShowExceptionDetails' ) ) {
                                $result->addContentValue(
                                        $path,
                                        'trace',
                                        $this->msg( 'api-exception-trace',
                                                get_class( $e ),
                                                $e->getFile(),
                                                $e->getLine(),
                                                MWExceptionHandler::getRedactedTraceAsString( $e )
                                        )->inLanguage( $formatter->getLanguage() )->text()
                                );
                        }
                }

                // Add the id and such
                $this->addRequestedFields( [ 'servedby' ] );

                return array_keys( $errorCodes );
        }

        /**
         * Add requested fields to the result
         * @param string[] $force Which fields to force even if not requested. Accepted values are:
         *  - servedby
         */
        protected function addRequestedFields( $force = [] ) {
                $result = $this->getResult();

                $requestid = $this->getParameter( 'requestid' );
                if ( $requestid !== null ) {
                        $result->addValue( null, 'requestid', $requestid, ApiResult::NO_SIZE_CHECK );
                }

                if ( $this->getConfig()->get( 'ShowHostnames' ) && (
                        in_array( 'servedby', $force, true ) || $this->getParameter( 'servedby' )
                ) ) {
                        $result->addValue( null, 'servedby', wfHostname(), ApiResult::NO_SIZE_CHECK );
                }

                if ( $this->getParameter( 'curtimestamp' ) ) {
                        $result->addValue( null, 'curtimestamp', wfTimestamp( TS_ISO_8601, time() ),
                                ApiResult::NO_SIZE_CHECK );
                }

                if ( $this->getParameter( 'responselanginfo' ) ) {
                        $result->addValue( null, 'uselang', $this->getLanguage()->getCode(),
                                ApiResult::NO_SIZE_CHECK );
                        $result->addValue( null, 'errorlang', $this->getErrorFormatter()->getLanguage()->getCode(),
                                ApiResult::NO_SIZE_CHECK );
                }
        }

        /**
         * Set up for the execution.
         * @return array
         */
        protected function setupExecuteAction() {
                $this->addRequestedFields();

                $params = $this->extractRequestParams();
                $this->mAction = $params['action'];

                return $params;
        }

        /**
         * Set up the module for response
         * @return ApiBase The module that will handle this action
         * @throws MWException
         * @throws ApiUsageException
         */
        protected function setupModule() {
                // Instantiate the module requested by the user
                $module = $this->mModuleMgr->getModule( $this->mAction, 'action' );
                if ( $module === null ) {
                        $this->dieWithError(
                                [ 'apierror-unknownaction', wfEscapeWikiText( $this->mAction ) ], 'unknown_action'
                        );
                }
                $moduleParams = $module->extractRequestParams();

                // Check token, if necessary
                if ( $module->needsToken() === true ) {
                        throw new MWException(
                                "Module '{$module->getModuleName()}' must be updated for the new token handling. " .
                                'See documentation for ApiBase::needsToken for details.'
                        );
                }
                if ( $module->needsToken() ) {
                        if ( !$module->mustBePosted() ) {
                                throw new MWException(
                                        "Module '{$module->getModuleName()}' must require POST to use tokens."
                                );
                        }

                        if ( !isset( $moduleParams['token'] ) ) {
                                $module->dieWithError( [ 'apierror-missingparam', 'token' ] );
                        }

                        $module->requirePostedParameters( [ 'token' ] );

                        if ( !$module->validateToken( $moduleParams['token'], $moduleParams ) ) {
                                $module->dieWithError( 'apierror-badtoken' );
                        }
                }

                return $module;
        }

        /**
         * Check the max lag if necessary
         * @param ApiBase $module Api module being used
         * @param array $params Array an array containing the request parameters.
         * @return bool True on success, false should exit immediately
         */
        protected function checkMaxLag( $module, $params ) {
                if ( $module->shouldCheckMaxlag() && isset( $params['maxlag'] ) ) {
                        $maxLag = $params['maxlag'];
                        list( $host, $lag ) = wfGetLB()->getMaxLag();
                        if ( $lag > $maxLag ) {
                                $response = $this->getRequest()->response();

                                $response->header( 'Retry-After: ' . max( intval( $maxLag ), 5 ) );
                                $response->header( 'X-Database-Lag: ' . intval( $lag ) );

                                if ( $this->getConfig()->get( 'ShowHostnames' ) ) {
                                        $this->dieWithError( [ 'apierror-maxlag', $lag, $host ] );
                                }

                                $this->dieWithError( [ 'apierror-maxlag-generic', $lag ], 'maxlag' );
                        }
                }

                return true;
        }

        /**
         * Check selected RFC 7232 precondition headers
         *
         * RFC 7232 envisions a particular model where you send your request to "a
         * resource", and for write requests that you can read "the resource" by
         * changing the method to GET. When the API receives a GET request, it
         * works out even though "the resource" from RFC 7232's perspective might
         * be many resources from MediaWiki's perspective. But it totally fails for
         * a POST, since what HTTP sees as "the resource" is probably just
         * "/api.php" with all the interesting bits in the body.
         *
         * Therefore, we only support RFC 7232 precondition headers for GET (and
         * HEAD). That means we don't need to bother with If-Match and
         * If-Unmodified-Since since they only apply to modification requests.
         *
         * And since we don't support Range, If-Range is ignored too.
         *
         * @since 1.26
         * @param ApiBase $module Api module being used
         * @return bool True on success, false should exit immediately
         */
        protected function checkConditionalRequestHeaders( $module ) {
                if ( $this->mInternalMode ) {
                        // No headers to check in internal mode
                        return true;
                }

                if ( $this->getRequest()->getMethod() !== 'GET' && $this->getRequest()->getMethod() !== 'HEAD' ) {
                        // Don't check POSTs
                        return true;
                }

                $return304 = false;

                $ifNoneMatch = array_diff(
                        $this->getRequest()->getHeader( 'If-None-Match', WebRequest::GETHEADER_LIST ) ?: [],
                        [ '' ]
                );
                if ( $ifNoneMatch ) {
                        if ( $ifNoneMatch === [ '*' ] ) {
                                // API responses always "exist"
                                $etag = '*';
                        } else {
                                $etag = $module->getConditionalRequestData( 'etag' );
                        }
                }
                if ( $ifNoneMatch && $etag !== null ) {
                        $test = substr( $etag, 0, 2 ) === 'W/' ? substr( $etag, 2 ) : $etag;
                        $match = array_map( function ( $s ) {
                                return substr( $s, 0, 2 ) === 'W/' ? substr( $s, 2 ) : $s;
                        }, $ifNoneMatch );
                        $return304 = in_array( $test, $match, true );
                } else {
                        $value = trim( $this->getRequest()->getHeader( 'If-Modified-Since' ) );

                        // Some old browsers sends sizes after the date, like this:
                        //  Wed, 20 Aug 2003 06:51:19 GMT; length=5202
                        // Ignore that.
                        $i = strpos( $value, ';' );
                        if ( $i !== false ) {
                                $value = trim( substr( $value, 0, $i ) );
                        }

                        if ( $value !== '' ) {
                                try {
                                        $ts = new MWTimestamp( $value );
                                        if (
                                                // RFC 7231 IMF-fixdate
                                                $ts->getTimestamp( TS_RFC2822 ) === $value ||
                                                // RFC 850
                                                $ts->format( 'l, d-M-y H:i:s' ) . ' GMT' === $value ||
                                                // asctime (with and without space-padded day)
                                                $ts->format( 'D M j H:i:s Y' ) === $value ||
                                                $ts->format( 'D M  j H:i:s Y' ) === $value
                                        ) {
                                                $lastMod = $module->getConditionalRequestData( 'last-modified' );
                                                if ( $lastMod !== null ) {
                                                        // Mix in some MediaWiki modification times
                                                        $modifiedTimes = [
                                                                'page' => $lastMod,
                                                                'user' => $this->getUser()->getTouched(),
                                                                'epoch' => $this->getConfig()->get( 'CacheEpoch' ),
                                                        ];
                                                        if ( $this->getConfig()->get( 'UseSquid' ) ) {
                                                                // T46570: the core page itself may not change, but resources might
                                                                $modifiedTimes['sepoch'] = wfTimestamp(
                                                                        TS_MW, time() - $this->getConfig()->get( 'SquidMaxage' )
                                                                );
                                                        }
                                                        Hooks::run( 'OutputPageCheckLastModified', [ &$modifiedTimes, $this->getOutput() ] );
                                                        $lastMod = max( $modifiedTimes );
                                                        $return304 = wfTimestamp( TS_MW, $lastMod ) <= $ts->getTimestamp( TS_MW );
                                                }
                                        }
                                } catch ( TimestampException $e ) {
                                        // Invalid timestamp, ignore it
                                }
                        }
                }

                if ( $return304 ) {
                        $this->getRequest()->response()->statusHeader( 304 );

                        // Avoid outputting the compressed representation of a zero-length body
                        MediaWiki\suppressWarnings();
                        ini_set( 'zlib.output_compression', 0 );
                        MediaWiki\restoreWarnings();
                        wfClearOutputBuffers();

                        return false;
                }

                return true;
        }

        /**
         * Check for sufficient permissions to execute
         * @param ApiBase $module An Api module
         */
        protected function checkExecutePermissions( $module ) {
                $user = $this->getUser();
                if ( $module->isReadMode() && !User::isEveryoneAllowed( 'read' ) &&
                        !$user->isAllowed( 'read' )
                ) {
                        $this->dieWithError( 'apierror-readapidenied' );
                }

                if ( $module->isWriteMode() ) {
                        if ( !$this->mEnableWrite ) {
                                $this->dieWithError( 'apierror-noapiwrite' );
                        } elseif ( !$user->isAllowed( 'writeapi' ) ) {
                                $this->dieWithError( 'apierror-writeapidenied' );
                        } elseif ( $this->getRequest()->getHeader( 'Promise-Non-Write-API-Action' ) ) {
                                $this->dieWithError( 'apierror-promised-nonwrite-api' );
                        }

                        $this->checkReadOnly( $module );
                }

                // Allow extensions to stop execution for arbitrary reasons.
                $message = false;
                if ( !Hooks::run( 'ApiCheckCanExecute', [ $module, $user, &$message ] ) ) {
                        $this->dieWithError( $message );
                }
        }

        /**
         * Check if the DB is read-only for this user
         * @param ApiBase $module An Api module
         */
        protected function checkReadOnly( $module ) {
                if ( wfReadOnly() ) {
                        $this->dieReadOnly();
                }

                if ( $module->isWriteMode()
                        && $this->getUser()->isBot()
                        && wfGetLB()->getServerCount() > 1
                ) {
                        $this->checkBotReadOnly();
                }
        }

        /**
         * Check whether we are readonly for bots
         */
        private function checkBotReadOnly() {
                // Figure out how many servers have passed the lag threshold
                $numLagged = 0;
                $lagLimit = $this->getConfig()->get( 'APIMaxLagThreshold' );
                $laggedServers = [];
                $loadBalancer = wfGetLB();
                foreach ( $loadBalancer->getLagTimes() as $serverIndex => $lag ) {
                        if ( $lag > $lagLimit ) {
                                ++$numLagged;
                                $laggedServers[] = $loadBalancer->getServerName( $serverIndex ) . " ({$lag}s)";
                        }
                }

                // If a majority of replica DBs are too lagged then disallow writes
                $replicaCount = wfGetLB()->getServerCount() - 1;
                if ( $numLagged >= ceil( $replicaCount / 2 ) ) {
                        $laggedServers = implode( ', ', $laggedServers );
                        wfDebugLog(
                                'api-readonly',
                                "Api request failed as read only because the following DBs are lagged: $laggedServers"
                        );

                        $this->dieWithError(
                                'readonly_lag',
                                'readonly',
                                [ 'readonlyreason' => "Waiting for $numLagged lagged database(s)" ]
                        );
                }
        }

        /**
         * Check asserts of the user's rights
         * @param array $params
         */
        protected function checkAsserts( $params ) {
                if ( isset( $params['assert'] ) ) {
                        $user = $this->getUser();
                        switch ( $params['assert'] ) {
                                case 'user':
                                        if ( $user->isAnon() ) {
                                                $this->dieWithError( 'apierror-assertuserfailed' );
                                        }
                                        break;
                                case 'bot':
                                        if ( !$user->isAllowed( 'bot' ) ) {
                                                $this->dieWithError( 'apierror-assertbotfailed' );
                                        }
                                        break;
                        }
                }
                if ( isset( $params['assertuser'] ) ) {
                        $assertUser = User::newFromName( $params['assertuser'], false );
                        if ( !$assertUser || !$this->getUser()->equals( $assertUser ) ) {
                                $this->dieWithError(
                                        [ 'apierror-assertnameduserfailed', wfEscapeWikiText( $params['assertuser'] ) ]
                                );
                        }
                }
        }

        /**
         * Check POST for external response and setup result printer
         * @param ApiBase $module An Api module
         * @param array $params An array with the request parameters
         */
        protected function setupExternalResponse( $module, $params ) {
                $request = $this->getRequest();
                if ( !$request->wasPosted() && $module->mustBePosted() ) {
                        // Module requires POST. GET request might still be allowed
                        // if $wgDebugApi is true, otherwise fail.
                        $this->dieWithErrorOrDebug( [ 'apierror-mustbeposted', $this->mAction ] );
                }

                // See if custom printer is used
                $this->mPrinter = $module->getCustomPrinter();
                if ( is_null( $this->mPrinter ) ) {
                        // Create an appropriate printer
                        $this->mPrinter = $this->createPrinterByName( $params['format'] );
                }

                if ( $request->getProtocol() === 'http' && (
                        $request->getSession()->shouldForceHTTPS() ||
                        ( $this->getUser()->isLoggedIn() &&
                                $this->getUser()->requiresHTTPS() )
                ) ) {
                        $this->addDeprecation( 'apiwarn-deprecation-httpsexpected', 'https-expected' );
                }
        }

        /**
         * Execute the actual module, without any error handling
         */
        protected function executeAction() {
                $params = $this->setupExecuteAction();
                $module = $this->setupModule();
                $this->mModule = $module;

                if ( !$this->mInternalMode ) {
                        $this->setRequestExpectations( $module );
                }

                $this->checkExecutePermissions( $module );

                if ( !$this->checkMaxLag( $module, $params ) ) {
                        return;
                }

                if ( !$this->checkConditionalRequestHeaders( $module ) ) {
                        return;
                }

                if ( !$this->mInternalMode ) {
                        $this->setupExternalResponse( $module, $params );
                }

                $this->checkAsserts( $params );

                // Execute
                $module->execute();
                Hooks::run( 'APIAfterExecute', [ &$module ] );

                $this->reportUnusedParams();

                if ( !$this->mInternalMode ) {
                        // append Debug information
                        MWDebug::appendDebugInfoToApiResult( $this->getContext(), $this->getResult() );

                        // Print result data
                        $this->printResult();
                }
        }

        /**
         * Set database connection, query, and write expectations given this module request
         * @param ApiBase $module
         */
        protected function setRequestExpectations( ApiBase $module ) {
                $limits = $this->getConfig()->get( 'TrxProfilerLimits' );
                $trxProfiler = Profiler::instance()->getTransactionProfiler();
                $trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
                if ( $this->getRequest()->hasSafeMethod() ) {
                        $trxProfiler->setExpectations( $limits['GET'], __METHOD__ );
                } elseif ( $this->getRequest()->wasPosted() && !$module->isWriteMode() ) {
                        $trxProfiler->setExpectations( $limits['POST-nonwrite'], __METHOD__ );
                        $this->getRequest()->markAsSafeRequest();
                } else {
                        $trxProfiler->setExpectations( $limits['POST'], __METHOD__ );
                }
        }

        /**
         * Log the preceding request
         * @param float $time Time in seconds
         * @param Exception $e Exception caught while processing the request
         */
        protected function logRequest( $time, $e = null ) {
                $request = $this->getRequest();
                $logCtx = [
                        'ts' => time(),
                        'ip' => $request->getIP(),
                        'userAgent' => $this->getUserAgent(),
                        'wiki' => wfWikiID(),
                        'timeSpentBackend' => (int)round( $time * 1000 ),
                        'hadError' => $e !== null,
                        'errorCodes' => [],
                        'params' => [],
                ];

                if ( $e ) {
                        foreach ( $this->errorMessagesFromException( $e ) as $msg ) {
                                $logCtx['errorCodes'][] = $msg->getApiCode();
                        }
                }

                // Construct space separated message for 'api' log channel
                $msg = "API {$request->getMethod()} " .
                        wfUrlencode( str_replace( ' ', '_', $this->getUser()->getName() ) ) .
                        " {$logCtx['ip']} " .
                        "T={$logCtx['timeSpentBackend']}ms";

                foreach ( $this->getParamsUsed() as $name ) {
                        $value = $request->getVal( $name );
                        if ( $value === null ) {
                                continue;
                        }

                        if ( strlen( $value ) > 256 ) {
                                $value = substr( $value, 0, 256 );
                                $encValue = $this->encodeRequestLogValue( $value ) . '[...]';
                        } else {
                                $encValue = $this->encodeRequestLogValue( $value );
                        }

                        $logCtx['params'][$name] = $value;
                        $msg .= " {$name}={$encValue}";
                }

                wfDebugLog( 'api', $msg, 'private' );
                // ApiAction channel is for structured data consumers
                wfDebugLog( 'ApiAction', '', 'private', $logCtx );
        }

        /**
         * Encode a value in a format suitable for a space-separated log line.
         * @param string $s
         * @return string
         */
        protected function encodeRequestLogValue( $s ) {
                static $table;
                if ( !$table ) {
                        $chars = ';@$!*(),/:';
                        $numChars = strlen( $chars );
                        for ( $i = 0; $i < $numChars; $i++ ) {
                                $table[rawurlencode( $chars[$i] )] = $chars[$i];
                        }
                }

                return strtr( rawurlencode( $s ), $table );
        }

        /**
         * Get the request parameters used in the course of the preceding execute() request
         * @return array
         */
        protected function getParamsUsed() {
                return array_keys( $this->mParamsUsed );
        }

        /**
         * Mark parameters as used
         * @param string|string[] $params
         */
        public function markParamsUsed( $params ) {
                $this->mParamsUsed += array_fill_keys( (array)$params, true );
        }

        /**
         * Get a request value, and register the fact that it was used, for logging.
         * @param string $name
         * @param mixed $default
         * @return mixed
         */
        public function getVal( $name, $default = null ) {
                $this->mParamsUsed[$name] = true;

                $ret = $this->getRequest()->getVal( $name );
                if ( $ret === null ) {
                        if ( $this->getRequest()->getArray( $name ) !== null ) {
                                // See bug 10262 for why we don't just implode( '|', ... ) the
                                // array.
                                $this->addWarning( [ 'apiwarn-unsupportedarray', $name ] );
                        }
                        $ret = $default;
                }
                return $ret;
        }

        /**
         * Get a boolean request value, and register the fact that the parameter
         * was used, for logging.
         * @param string $name
         * @return bool
         */
        public function getCheck( $name ) {
                return $this->getVal( $name, null ) !== null;
        }

        /**
         * Get a request upload, and register the fact that it was used, for logging.
         *
         * @since 1.21
         * @param string $name Parameter name
         * @return WebRequestUpload
         */
        public function getUpload( $name ) {
                $this->mParamsUsed[$name] = true;

                return $this->getRequest()->getUpload( $name );
        }

        /**
         * Report unused parameters, so the client gets a hint in case it gave us parameters we don't know,
         * for example in case of spelling mistakes or a missing 'g' prefix for generators.
         */
        protected function reportUnusedParams() {
                $paramsUsed = $this->getParamsUsed();
                $allParams = $this->getRequest()->getValueNames();

                if ( !$this->mInternalMode ) {
                        // Printer has not yet executed; don't warn that its parameters are unused
                        $printerParams = $this->mPrinter->encodeParamName(
                                array_keys( $this->mPrinter->getFinalParams() ?: [] )
                        );
                        $unusedParams = array_diff( $allParams, $paramsUsed, $printerParams );
                } else {
                        $unusedParams = array_diff( $allParams, $paramsUsed );
                }

                if ( count( $unusedParams ) ) {
                        $this->addWarning( [
                                'apierror-unrecognizedparams',
                                Message::listParam( array_map( 'wfEscapeWikiText', $unusedParams ), 'comma' ),
                                count( $unusedParams )
                        ] );
                }
        }

        /**
         * Print results using the current printer
         *
         * @param int $httpCode HTTP status code, or 0 to not change
         */
        protected function printResult( $httpCode = 0 ) {
                if ( $this->getConfig()->get( 'DebugAPI' ) !== false ) {
                        $this->addWarning( 'apiwarn-wgDebugAPI' );
                }

                $printer = $this->mPrinter;
                $printer->initPrinter( false );
                if ( $httpCode ) {
                        $printer->setHttpStatus( $httpCode );
                }
                $printer->execute();
                $printer->closePrinter();
        }

        /**
         * @return bool
         */
        public function isReadMode() {
                return false;
        }

        /**
         * See ApiBase for description.
         *
         * @return array
         */
        public function getAllowedParams() {
                return [
                        'action' => [
                                ApiBase::PARAM_DFLT => 'help',
                                ApiBase::PARAM_TYPE => 'submodule',
                        ],
                        'format' => [
                                ApiBase::PARAM_DFLT => ApiMain::API_DEFAULT_FORMAT,
                                ApiBase::PARAM_TYPE => 'submodule',
                        ],
                        'maxlag' => [
                                ApiBase::PARAM_TYPE => 'integer'
                        ],
                        'smaxage' => [
                                ApiBase::PARAM_TYPE => 'integer',
                                ApiBase::PARAM_DFLT => 0
                        ],
                        'maxage' => [
                                ApiBase::PARAM_TYPE => 'integer',
                                ApiBase::PARAM_DFLT => 0
                        ],
                        'assert' => [
                                ApiBase::PARAM_TYPE => [ 'user', 'bot' ]
                        ],
                        'assertuser' => [
                                ApiBase::PARAM_TYPE => 'user',
                        ],
                        'requestid' => null,
                        'servedby' => false,
                        'curtimestamp' => false,
                        'responselanginfo' => false,
                        'origin' => null,
                        'uselang' => [
                                ApiBase::PARAM_DFLT => self::API_DEFAULT_USELANG,
                        ],
                        'errorformat' => [
                                ApiBase::PARAM_TYPE => [ 'plaintext', 'wikitext', 'html', 'raw', 'none', 'bc' ],
                                ApiBase::PARAM_DFLT => 'bc',
                        ],
                        'errorlang' => [
                                ApiBase::PARAM_DFLT => 'uselang',
                        ],
                        'errorsuselocal' => [
                                ApiBase::PARAM_DFLT => false,
                        ],
                ];
        }

        /** @see ApiBase::getExamplesMessages() */
        protected function getExamplesMessages() {
                return [
                        'action=help'
                                => 'apihelp-help-example-main',
                        'action=help&recursivesubmodules=1'
                                => 'apihelp-help-example-recursive',
                ];
        }

        public function modifyHelp( array &$help, array $options, array &$tocData ) {
                // Wish PHP had an "array_insert_before". Instead, we have to manually
                // reindex the array to get 'permissions' in the right place.
                $oldHelp = $help;
                $help = [];
                foreach ( $oldHelp as $k => $v ) {
                        if ( $k === 'submodules' ) {
                                $help['permissions'] = '';
                        }
                        $help[$k] = $v;
                }
                $help['datatypes'] = '';
                $help['credits'] = '';

                // Fill 'permissions'
                $help['permissions'] .= Html::openElement( 'div',
                        [ 'class' => 'apihelp-block apihelp-permissions' ] );
                $m = $this->msg( 'api-help-permissions' );
                if ( !$m->isDisabled() ) {
                        $help['permissions'] .= Html::rawElement( 'div', [ 'class' => 'apihelp-block-head' ],
                                $m->numParams( count( self::$mRights ) )->parse()
                        );
                }
                $help['permissions'] .= Html::openElement( 'dl' );
                foreach ( self::$mRights as $right => $rightMsg ) {
                        $help['permissions'] .= Html::element( 'dt', null, $right );

                        $rightMsg = $this->msg( $rightMsg['msg'], $rightMsg['params'] )->parse();
                        $help['permissions'] .= Html::rawElement( 'dd', null, $rightMsg );

                        $groups = array_map( function ( $group ) {
                                return $group == '*' ? 'all' : $group;
                        }, User::getGroupsWithPermission( $right ) );

                        $help['permissions'] .= Html::rawElement( 'dd', null,
                                $this->msg( 'api-help-permissions-granted-to' )
                                        ->numParams( count( $groups ) )
                                        ->params( Message::listParam( $groups ) )
                                        ->parse()
                        );
                }
                $help['permissions'] .= Html::closeElement( 'dl' );
                $help['permissions'] .= Html::closeElement( 'div' );

                // Fill 'datatypes' and 'credits', if applicable
                if ( empty( $options['nolead'] ) ) {
                        $level = $options['headerlevel'];
                        $tocnumber = &$options['tocnumber'];

                        $header = $this->msg( 'api-help-datatypes-header' )->parse();

                        // Add an additional span with sanitized ID
                        if ( !$this->getConfig()->get( 'ExperimentalHtmlIds' ) ) {
                                $header = Html::element( 'span', [ 'id' => Sanitizer::escapeId( 'main/datatypes' ) ] ) .
                                        $header;
                        }
                        $help['datatypes'] .= Html::rawElement( 'h' . min( 6, $level ),
                                [ 'id' => 'main/datatypes', 'class' => 'apihelp-header' ],
                                $header
                        );
                        $help['datatypes'] .= $this->msg( 'api-help-datatypes' )->parseAsBlock();
                        if ( !isset( $tocData['main/datatypes'] ) ) {
                                $tocnumber[$level]++;
                                $tocData['main/datatypes'] = [
                                        'toclevel' => count( $tocnumber ),
                                        'level' => $level,
                                        'anchor' => 'main/datatypes',
                                        'line' => $header,
                                        'number' => implode( '.', $tocnumber ),
                                        'index' => false,
                                ];
                        }

                        // Add an additional span with sanitized ID
                        if ( !$this->getConfig()->get( 'ExperimentalHtmlIds' ) ) {
                                $header = Html::element( 'span', [ 'id' => Sanitizer::escapeId( 'main/credits' ) ] ) .
                                        $header;
                        }
                        $header = $this->msg( 'api-credits-header' )->parse();
                        $help['credits'] .= Html::rawElement( 'h' . min( 6, $level ),
                                [ 'id' => 'main/credits', 'class' => 'apihelp-header' ],
                                $header
                        );
                        $help['credits'] .= $this->msg( 'api-credits' )->useDatabase( false )->parseAsBlock();
                        if ( !isset( $tocData['main/credits'] ) ) {
                                $tocnumber[$level]++;
                                $tocData['main/credits'] = [
                                        'toclevel' => count( $tocnumber ),
                                        'level' => $level,
                                        'anchor' => 'main/credits',
                                        'line' => $header,
                                        'number' => implode( '.', $tocnumber ),
                                        'index' => false,
                                ];
                        }
                }
        }

        private $mCanApiHighLimits = null;

        /**
         * Check whether the current user is allowed to use high limits
         * @return bool
         */
        public function canApiHighLimits() {
                if ( !isset( $this->mCanApiHighLimits ) ) {
                        $this->mCanApiHighLimits = $this->getUser()->isAllowed( 'apihighlimits' );
                }

                return $this->mCanApiHighLimits;
        }

        /**
         * Overrides to return this instance's module manager.
         * @return ApiModuleManager
         */
        public function getModuleManager() {
                return $this->mModuleMgr;
        }

        /**
         * Fetches the user agent used for this request
         *
         * The value will be the combination of the 'Api-User-Agent' header (if
         * any) and the standard User-Agent header (if any).
         *
         * @return string
         */
        public function getUserAgent() {
                return trim(
                        $this->getRequest()->getHeader( 'Api-user-agent' ) . ' ' .
                        $this->getRequest()->getHeader( 'User-agent' )
                );
        }
}

/**
 * For really cool vim folding this needs to be at the end:
 * vim: foldmarker=@{,@} foldmethod=marker
 */