Merge "rest: Return a 400 for invalid render IDs"

[mediawiki.git] / includes / actions / ActionEntryPoint.php

<?php

namespace MediaWiki\Actions;

use Action;
use Article;
use BadTitleError;
use ErrorPageError;
use HTMLFileCache;
use HttpError;
use MediaWiki\Context\RequestContext;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiEntryPoint;
use MediaWiki\Output\OutputPage;
use MediaWiki\Permissions\PermissionStatus;
use MediaWiki\Profiler\ProfilingContext;
use MediaWiki\Request\DerivativeRequest;
use MediaWiki\Request\WebRequest;
use MediaWiki\SpecialPage\RedirectSpecialPage;
use MediaWiki\SpecialPage\SpecialPage;
use MediaWiki\Title\MalformedTitleException;
use MediaWiki\Title\Title;
use MediaWiki\User\User;
use MWExceptionRenderer;
use PermissionsError;
use Profiler;
use Throwable;
use UnexpectedValueException;
use ViewAction;
use WikiFilePage;
use Wikimedia\Rdbms\DBConnectionError;

/**
 * The index.php entry point for web browser navigations, usually routed to
 * an Action or SpecialPage subclass.
 *
 * @internal For use in index.php
 * @ingroup entrypoint
 */
class ActionEntryPoint extends MediaWikiEntryPoint {

        /**
         * Overwritten to narrow the return type to RequestContext
         */
        protected function getContext(): RequestContext {
                /** @var RequestContext $context */
                $context = parent::getContext();

                // @phan-suppress-next-line PhanTypeMismatchReturnSuperType see $context in the constructor
                return $context;
        }

        protected function getOutput(): OutputPage {
                return $this->getContext()->getOutput();
        }

        protected function getUser(): User {
                return $this->getContext()->getUser();
        }

        protected function handleTopLevelError( Throwable $e ) {
                $context = $this->getContext();
                $action = $context->getRequest()->getRawVal( 'action' ) ?? 'view';
                if (
                        $e instanceof DBConnectionError &&
                        $context->hasTitle() &&
                        $context->getTitle()->canExist() &&
                        in_array( $action, [ 'view', 'history' ], true ) &&
                        HTMLFileCache::useFileCache( $context, HTMLFileCache::MODE_OUTAGE )
                ) {
                        // Try to use any (even stale) file during outages...
                        $cache = new HTMLFileCache( $context->getTitle(), $action );
                        if ( $cache->isCached() ) {
                                $cache->loadFromFileCache( $context, HTMLFileCache::MODE_OUTAGE );
                                $this->print( MWExceptionRenderer::getHTML( $e ) );
                                $this->exit();
                        }
                }

                parent::handleTopLevelError( $e );
        }

        /**
         * Determine and send the response headers and body for this web request
         */
        protected function execute() {
                // phpcs:ignore MediaWiki.Usage.DeprecatedGlobalVariables.Deprecated$wgTitle
                global $wgTitle;

                // Get title from request parameters,
                // is set on the fly by parseTitle the first time.
                $title = $this->getTitle();
                $wgTitle = $title;

                $request = $this->getContext()->getRequest();
                // Set DB query expectations for this HTTP request
                $trxLimits = $this->getConfig( MainConfigNames::TrxProfilerLimits );
                $trxProfiler = Profiler::instance()->getTransactionProfiler();
                $trxProfiler->setLogger( LoggerFactory::getInstance( 'rdbms' ) );
                $trxProfiler->setStatsFactory( $this->getStatsFactory() );
                $trxProfiler->setRequestMethod( $request->getMethod() );
                if ( $request->hasSafeMethod() ) {
                        $trxProfiler->setExpectations( $trxLimits['GET'], __METHOD__ );
                } else {
                        $trxProfiler->setExpectations( $trxLimits['POST'], __METHOD__ );
                }

                if ( $this->maybeDoHttpsRedirect() ) {
                        return;
                }

                $context = $this->getContext();
                $output = $context->getOutput();

                // NOTE: HTMLFileCache::useFileCache() is not used in WMF production but is
                //       here to provide third-party wikis with a way to enable caching for
                //       "view" and "history" actions. It's triggered by the use of $wgUseFileCache
                //       when set to true in LocalSettings.php.
                if ( $title->canExist() && HTMLFileCache::useFileCache( $context ) ) {
                        // getAction() may trigger DB queries, so avoid eagerly initializing it if possible.
                        // This reduces the cost of requests that exit early due to tryNormaliseRedirect()
                        // or a MediaWikiPerformAction / BeforeInitialize hook handler.
                        $action = $this->getAction();
                        // Try low-level file cache hit
                        $cache = new HTMLFileCache( $title, $action );
                        if ( $cache->isCacheGood( /* Assume up to date */ ) ) {
                                // Check incoming headers to see if client has this cached
                                $timestamp = $cache->cacheTimestamp();
                                if ( !$output->checkLastModified( $timestamp ) ) {
                                        $cache->loadFromFileCache( $context );
                                }
                                // Do any stats increment/watchlist stuff, assuming user is viewing the
                                // latest revision (which should always be the case for file cache)
                                $context->getWikiPage()->doViewUpdates( $context->getAuthority() );
                                // Tell OutputPage that output is taken care of
                                $output->disable();

                                return;
                        }
                }

                try {
                        // Actually do the work of the request and build up any output
                        $this->performRequest();
                } catch ( ErrorPageError $e ) {
                        // TODO: Should ErrorPageError::report accept a OutputPage parameter?
                        $e->report( ErrorPageError::STAGE_OUTPUT );
                        $output->considerCacheSettingsFinal();
                        // T64091: while exceptions are convenient to bubble up GUI errors,
                        // they are not internal application faults. As with normal requests, this
                        // should commit, print the output, do deferred updates, jobs, and profiling.
                }

                $this->prepareForOutput();

                // Ask OutputPage/Skin to stage the output (HTTP response body and headers).
                // Flush the output to the client unless an exception occurred.
                // Note that the OutputPage object in $context may have been replaced,
                // so better fetch it again here.
                $output = $context->getOutput();
                $this->outputResponsePayload( $output->output( true ) );
        }

        /**
         * If the stars are suitably aligned, do an HTTP->HTTPS redirect
         *
         * Note: Do this after $wgTitle is setup, otherwise the hooks run from
         * isRegistered() will do all sorts of weird stuff.
         *
         * @return bool True if the redirect was done. Handling of the request
         *   should be aborted. False if no redirect was done.
         */
        protected function maybeDoHttpsRedirect() {
                if ( !$this->shouldDoHttpRedirect() ) {
                        return false;
                }

                $context = $this->getContext();
                $request = $context->getRequest();
                $oldUrl = $request->getFullRequestURL();
                $redirUrl = preg_replace( '#^http://#', 'https://', $oldUrl );

                if ( $request->wasPosted() ) {
                        // This is weird and we'd hope it almost never happens. This
                        // means that a POST came in via HTTP and policy requires us
                        // redirecting to HTTPS. It's likely such a request is going
                        // to fail due to post data being lost, but let's try anyway
                        // and just log the instance.

                        // @todo FIXME: See if we could issue a 307 or 308 here, need
                        // to see how clients (automated & browser) behave when we do
                        wfDebugLog( 'RedirectedPosts', "Redirected from HTTP to HTTPS: $oldUrl" );
                }
                // Setup dummy Title, otherwise OutputPage::redirect will fail
                $title = Title::newFromText( 'REDIR', NS_MAIN );
                $context->setTitle( $title );
                // Since we only do this redir to change proto, always send a vary header
                $output = $context->getOutput();
                $output->addVaryHeader( 'X-Forwarded-Proto' );
                $output->redirect( $redirUrl );
                $output->output();

                return true;
        }

        protected function doPrepareForOutput() {
                parent::doPrepareForOutput();

                // If needed, push a deferred update to run jobs after the output is sent
                $this->schedulePostSendJobs();
        }

        protected function schedulePostSendJobs() {
                // Recursion guard for $wgRunJobsAsync
                if ( $this->getTitle()->isSpecial( 'RunJobs' ) ) {
                        return;
                }

                parent::schedulePostSendJobs();
        }

        /**
         * Parse the request to get the Title object
         *
         * @throws MalformedTitleException If a title has been provided by the user, but is invalid.
         * @param WebRequest $request
         * @return Title Title object to be $wgTitle
         */
        protected function parseTitle( $request ) {
                $curid = $request->getInt( 'curid' );
                $title = $request->getText( 'title' );

                $ret = null;
                if ( $curid ) {
                        // URLs like this are generated by RC, because rc_title isn't always accurate
                        $ret = Title::newFromID( $curid );
                }
                if ( $ret === null ) {
                        $ret = Title::newFromURL( $title );
                        if ( $ret !== null ) {
                                // Alias NS_MEDIA page URLs to NS_FILE...we only use NS_MEDIA
                                // in wikitext links to tell Parser to make a direct file link
                                if ( $ret->getNamespace() === NS_MEDIA ) {
                                        $ret = Title::makeTitle( NS_FILE, $ret->getDBkey() );
                                }
                                // Check variant links so that interwiki links don't have to worry
                                // about the possible different language variants
                                $services = $this->getServiceContainer();
                                $languageConverter = $services
                                        ->getLanguageConverterFactory()
                                        ->getLanguageConverter( $services->getContentLanguage() );
                                if ( $languageConverter->hasVariants() && !$ret->exists() ) {
                                        $languageConverter->findVariantLink( $title, $ret );
                                }
                        }
                }

                // If title is not provided, always allow oldid and diff to set the title.
                // If title is provided, allow oldid and diff to override the title, unless
                // we are talking about a special page which might use these parameters for
                // other purposes.
                if ( $ret === null || !$ret->isSpecialPage() ) {
                        // We can have urls with just ?diff=,?oldid= or even just ?diff=
                        $oldid = $request->getInt( 'oldid' );
                        $oldid = $oldid ?: $request->getInt( 'diff' );
                        // Allow oldid to override a changed or missing title
                        if ( $oldid ) {
                                $revRecord = $this->getServiceContainer()
                                        ->getRevisionLookup()
                                        ->getRevisionById( $oldid );
                                if ( $revRecord ) {
                                        $ret = Title::newFromLinkTarget(
                                                $revRecord->getPageAsLinkTarget()
                                        );
                                }
                        }
                }

                if ( $ret === null && $request->getCheck( 'search' ) ) {
                        // Compatibility with old search URLs which didn't use Special:Search
                        // Just check for presence here, so blank requests still
                        // show the search page when using ugly URLs (T10054).
                        $ret = SpecialPage::getTitleFor( 'Search' );
                }

                if ( $ret === null || !$ret->isSpecialPage() ) {
                        // Compatibility with old URLs for Special:RevisionDelete/Special:EditTags (T323338)
                        $actionName = $request->getRawVal( 'action' );
                        if (
                                $actionName === 'revisiondelete' ||
                                ( $actionName === 'historysubmit' && $request->getBool( 'revisiondelete' ) )
                        ) {
                                $ret = SpecialPage::getTitleFor( 'Revisiondelete' );
                        } elseif (
                                $actionName === 'editchangetags' ||
                                ( $actionName === 'historysubmit' && $request->getBool( 'editchangetags' ) )
                        ) {
                                $ret = SpecialPage::getTitleFor( 'EditTags' );
                        }
                }

                // Use the main page as default title if nothing else has been provided
                if ( $ret === null
                        && strval( $title ) === ''
                        && !$request->getCheck( 'curid' )
                        && $request->getRawVal( 'action' ) !== 'delete'
                ) {
                        $ret = Title::newMainPage();
                }

                if ( $ret === null || ( $ret->getDBkey() == '' && !$ret->isExternal() ) ) {
                        // If we get here, we definitely don't have a valid title; throw an exception.
                        // Try to get detailed invalid title exception first, fall back to MalformedTitleException.
                        Title::newFromTextThrow( $title );
                        throw new MalformedTitleException( 'badtitletext', $title );
                }

                return $ret;
        }

        /**
         * Get the Title object that we'll be acting on, as specified in the WebRequest
         * @return Title
         */
        public function getTitle() {
                $context = $this->getContext();

                if ( !$context->hasTitle() ) {
                        try {
                                $context->setTitle( $this->parseTitle( $context->getRequest() ) );
                        } catch ( MalformedTitleException $ex ) {
                                $context->setTitle( SpecialPage::getTitleFor( 'Badtitle' ) );
                        }
                }
                return $context->getTitle();
        }

        /**
         * Returns the name of the action that will be executed.
         *
         * @note This is public for the benefit of extensions that implement
         * the BeforeInitialize or MediaWikiPerformAction hooks.
         *
         * @return string Action
         */
        public function getAction(): string {
                return $this->getContext()->getActionName();
        }

        /**
         * Performs the request.
         * - bad titles
         * - read restriction
         * - local interwiki redirects
         * - redirect loop
         * - special pages
         * - normal pages
         *
         * @throws PermissionsError|BadTitleError|HttpError
         * @return void
         */
        protected function performRequest() {
                // phpcs:ignore MediaWiki.Usage.DeprecatedGlobalVariables.Deprecated$wgTitle
                global $wgTitle;

                $context = $this->getContext();

                $request = $context->getRequest();
                $output = $context->getOutput();

                if ( $request->getRawVal( 'printable' ) === 'yes' ) {
                        $output->setPrintable();
                }

                $user = $context->getUser();
                $title = $context->getTitle();
                $requestTitle = $title;

                $userOptionsLookup = $this->getServiceContainer()->getUserOptionsLookup();
                if ( $userOptionsLookup->getBoolOption( $user, 'forcesafemode' ) ) {
                        $request->setVal( 'safemode', '1' );
                }

                $this->getHookRunner()->onBeforeInitialize( $title, null, $output, $user, $request, $this );

                // Invalid titles. T23776: The interwikis must redirect even if the page name is empty.
                if ( $title === null || ( $title->getDBkey() == '' && !$title->isExternal() )
                        || $title->isSpecial( 'Badtitle' )
                ) {
                        $context->setTitle( SpecialPage::getTitleFor( 'Badtitle' ) );
                        try {
                                $this->parseTitle( $request );
                        } catch ( MalformedTitleException $ex ) {
                                throw new BadTitleError( $ex );
                        }
                        throw new BadTitleError();
                }

                // Check user's permissions to read this page.
                // We have to check here to catch special pages etc.
                // We will check again in Article::view().
                $permissionStatus = PermissionStatus::newEmpty();
                if ( !$context->getAuthority()->authorizeRead( 'read', $title, $permissionStatus ) ) {
                        // T34276: allowing the skin to generate output with $wgTitle or
                        // $context->title set to the input title would allow anonymous users to
                        // determine whether a page exists, potentially leaking private data. In fact, the
                        // curid and oldid request  parameters would allow page titles to be enumerated even
                        // when they are not guessable. So we reset the title to Special:Badtitle before the
                        // permissions error is displayed.

                        // The skin mostly uses $context->getTitle() these days, but some extensions
                        // still use $wgTitle.
                        $badTitle = SpecialPage::getTitleFor( 'Badtitle' );
                        $context->setTitle( $badTitle );
                        $wgTitle = $badTitle;

                        throw new PermissionsError( 'read', $permissionStatus );
                }

                // Interwiki redirects
                if ( $title->isExternal() ) {
                        $rdfrom = $request->getVal( 'rdfrom' );
                        if ( $rdfrom ) {
                                $url = $title->getFullURL( [ 'rdfrom' => $rdfrom ] );
                        } else {
                                $query = $request->getQueryValues();
                                unset( $query['title'] );
                                $url = $title->getFullURL( $query );
                        }
                        // Check for a redirect loop
                        if ( $url !== $request->getFullRequestURL() && $title->isLocal() ) {
                                // 301 so google et al report the target as the actual url.
                                $output->redirect( $url, 301 );
                        } else {
                                $context->setTitle( SpecialPage::getTitleFor( 'Badtitle' ) );
                                try {
                                        $this->parseTitle( $request );
                                } catch ( MalformedTitleException $ex ) {
                                        throw new BadTitleError( $ex );
                                }
                                throw new BadTitleError();
                        }
                        // Handle any other redirects.
                        // Redirect loops, titleless URL, $wgUsePathInfo URLs, and URLs with a variant
                } elseif ( !$this->tryNormaliseRedirect( $title ) ) {
                        // Prevent information leak via Special:MyPage et al (T109724)
                        $spFactory = $this->getServiceContainer()->getSpecialPageFactory();
                        if ( $title->isSpecialPage() ) {
                                $specialPage = $spFactory->getPage( $title->getDBkey() );
                                if ( $specialPage instanceof RedirectSpecialPage ) {
                                        $specialPage->setContext( $context );
                                        if ( $this->getConfig( MainConfigNames::HideIdentifiableRedirects )
                                                && $specialPage->personallyIdentifiableTarget()
                                        ) {
                                                [ , $subpage ] = $spFactory->resolveAlias( $title->getDBkey() );
                                                $target = $specialPage->getRedirect( $subpage );
                                                // Target can also be true. We let that case fall through to normal processing.
                                                if ( $target instanceof Title ) {
                                                        if ( $target->isExternal() ) {
                                                                // Handle interwiki redirects
                                                                $target = SpecialPage::getTitleFor(
                                                                        'GoToInterwiki',
                                                                        'force/' . $target->getPrefixedDBkey()
                                                                );
                                                        }

                                                        $query = $specialPage->getRedirectQuery( $subpage ) ?: [];
                                                        $derivateRequest = new DerivativeRequest( $request, $query );
                                                        $derivateRequest->setRequestURL( $request->getRequestURL() );
                                                        $context->setRequest( $derivateRequest );
                                                        // Do not varnish cache these. May vary even for anons
                                                        $output->lowerCdnMaxage( 0 );
                                                        // NOTE: This also clears any action cache.
                                                        // Action should not have been computed yet, but if it was,
                                                        // we reset it because special pages only support "view".
                                                        $context->setTitle( $target );
                                                        $wgTitle = $target;
                                                        $title = $target;
                                                        $output->addJsConfigVars( [
                                                                'wgInternalRedirectTargetUrl' => $target->getLinkURL( $query ),
                                                        ] );
                                                        $output->addModules( 'mediawiki.action.view.redirect' );

                                                        // If the title is invalid, redirect but show the correct bad title error - T297407
                                                        if ( !$target->isValid() ) {
                                                                try {
                                                                        $this->getServiceContainer()->getTitleParser()
                                                                                ->parseTitle( $target->getPrefixedText() );
                                                                } catch ( MalformedTitleException $ex ) {
                                                                        throw new BadTitleError( $ex );
                                                                }
                                                                throw new BadTitleError();
                                                        }
                                                }
                                        }
                                }
                        }

                        // Special pages ($title may have changed since if statement above)
                        if ( $title->isSpecialPage() ) {
                                // Actions that need to be made when we have a special pages
                                $spFactory->executePath( $title, $context );
                        } else {
                                // ...otherwise treat it as an article view. The article
                                // may still be a wikipage redirect to another article or URL.
                                $article = $this->initializeArticle();
                                if ( is_object( $article ) ) {
                                        $this->performAction( $article, $requestTitle );
                                } elseif ( is_string( $article ) ) {
                                        $output->redirect( $article );
                                } else {
                                        throw new UnexpectedValueException( "Shouldn't happen: MediaWiki::initializeArticle()"
                                                . " returned neither an object nor a URL" );
                                }
                        }
                        $output->considerCacheSettingsFinal();
                }
        }

        /**
         * Handle redirects for uncanonical title requests.
         *
         * Handles:
         * - Redirect loops.
         * - No title in URL.
         * - $wgUsePathInfo URLs.
         * - URLs with a variant.
         * - Other non-standard URLs (as long as they have no extra query parameters).
         *
         * Behaviour:
         * - Normalise title values:
         *   /wiki/Foo%20Bar -> /wiki/Foo_Bar
         * - Normalise empty title:
         *   /wiki/ -> /wiki/Main
         *   /w/index.php?title= -> /wiki/Main
         * - Don't redirect anything with query parameters other than 'title' or 'action=view'.
         *
         * @param Title $title
         * @return bool True if a redirect was set.
         * @throws HttpError
         */
        protected function tryNormaliseRedirect( Title $title ): bool {
                $request = $this->getRequest();
                $output = $this->getOutput();

                if ( ( $request->getRawVal( 'action' ) ?? 'view' ) !== 'view'
                        || $request->wasPosted()
                        || ( $request->getCheck( 'title' )
                                && $title->getPrefixedDBkey() == $request->getText( 'title' ) )
                        || count( $request->getValueNames( [ 'action', 'title' ] ) )
                        || !$this->getHookRunner()->onTestCanonicalRedirect( $request, $title, $output )
                ) {
                        return false;
                }

                if ( $this->getConfig( MainConfigNames::MainPageIsDomainRoot ) && $request->getRequestURL() === '/' ) {
                        return false;
                }

                $services = $this->getServiceContainer();

                if ( $title->isSpecialPage() ) {
                        [ $name, $subpage ] = $services->getSpecialPageFactory()
                                ->resolveAlias( $title->getDBkey() );

                        if ( $name ) {
                                $title = SpecialPage::getTitleFor( $name, $subpage );
                        }
                }
                // Redirect to canonical url, make it a 301 to allow caching
                $targetUrl = (string)$services->getUrlUtils()->expand( $title->getFullURL(), PROTO_CURRENT );
                if ( $targetUrl == $request->getFullRequestURL() ) {
                        $message = "Redirect loop detected!\n\n" .
                                "This means the wiki got confused about what page was " .
                                "requested; this sometimes happens when moving a wiki " .
                                "to a new server or changing the server configuration.\n\n";

                        if ( $this->getConfig( MainConfigNames::UsePathInfo ) ) {
                                $message .= "The wiki is trying to interpret the page " .
                                        "title from the URL path portion (PATH_INFO), which " .
                                        "sometimes fails depending on the web server. Try " .
                                        "setting \"\$wgUsePathInfo = false;\" in your " .
                                        "LocalSettings.php, or check that \$wgArticlePath " .
                                        "is correct.";
                        } else {
                                $message .= "Your web server was detected as possibly not " .
                                        "supporting URL path components (PATH_INFO) correctly; " .
                                        "check your LocalSettings.php for a customized " .
                                        "\$wgArticlePath setting and/or toggle \$wgUsePathInfo " .
                                        "to true.";
                        }
                        throw new HttpError( 500, $message );
                }
                $output->setCdnMaxage( 1200 );
                $output->redirect( $targetUrl, '301' );
                return true;
        }

        /**
         * Initialize the main Article object for "standard" actions (view, etc)
         * Create an Article object for the page, following redirects if needed.
         *
         * @return Article|string An Article, or a string to redirect to another URL
         */
        protected function initializeArticle() {
                $context = $this->getContext();

                $title = $context->getTitle();
                $services = $this->getServiceContainer();
                if ( $context->canUseWikiPage() ) {
                        // Optimization: Reuse the WikiPage instance from context, to avoid
                        // repeat fetching or computation of data already loaded.
                        $page = $context->getWikiPage();
                } else {
                        // This case should not happen, but just in case.
                        // @TODO: remove this or use an exception
                        $page = $services->getWikiPageFactory()->newFromTitle( $title );
                        $context->setWikiPage( $page );
                        wfWarn( "RequestContext::canUseWikiPage() returned false" );
                }

                // Make GUI wrapper for the WikiPage
                $article = Article::newFromWikiPage( $page, $context );

                // Skip some unnecessary code if the content model doesn't support redirects
                // Use the page content model rather than invoking Title::getContentModel()
                // to avoid querying page data twice (T206498)
                if ( !$page->getContentHandler()->supportsRedirects() ) {
                        return $article;
                }

                $request = $context->getRequest();

                // Namespace might change when using redirects
                // Check for redirects ...
                $action = $request->getRawVal( 'action' ) ?? 'view';
                $file = ( $page instanceof WikiFilePage ) ? $page->getFile() : null;
                if ( ( $action == 'view' || $action == 'render' ) // ... for actions that show content
                        && !$request->getCheck( 'oldid' ) // ... and are not old revisions
                        && !$request->getCheck( 'diff' ) // ... and not when showing diff
                        && $request->getRawVal( 'redirect' ) !== 'no' // ... unless explicitly told not to
                        // ... and the article is not a non-redirect image page with associated file
                        && !( is_object( $file ) && $file->exists() && !$file->getRedirected() )
                ) {
                        // Give extensions a change to ignore/handle redirects as needed
                        $ignoreRedirect = $target = false;

                        $this->getHookRunner()->onInitializeArticleMaybeRedirect( $title, $request,
                                // @phan-suppress-next-line PhanTypeMismatchArgument Type mismatch on pass-by-ref args
                                $ignoreRedirect, $target, $article );
                        $page = $article->getPage(); // reflect any hook changes

                        // Follow redirects only for... redirects.
                        // If $target is set, then a hook wanted to redirect.
                        if ( !$ignoreRedirect && ( $target || $page->isRedirect() ) ) {
                                // Is the target already set by an extension?
                                $target = $target ?: $page->followRedirect();
                                if ( is_string( $target ) && !$this->getConfig( MainConfigNames::DisableHardRedirects ) ) {
                                        // we'll need to redirect
                                        return $target;
                                }
                                if ( is_object( $target ) ) {
                                        // Rewrite environment to redirected article
                                        $rpage = $services->getWikiPageFactory()->newFromTitle( $target );
                                        $rpage->loadPageData();
                                        if ( $rpage->exists() || ( is_object( $file ) && !$file->isLocal() ) ) {
                                                $rarticle = Article::newFromWikiPage( $rpage, $context );
                                                $rarticle->setRedirectedFrom( $title );

                                                $article = $rarticle;
                                                // NOTE: This also clears any action cache
                                                $context->setTitle( $target );
                                                $context->setWikiPage( $article->getPage() );
                                        }
                                }
                        }
                }

                return $article;
        }

        /**
         * Perform one of the "standard" actions
         *
         * @param Article $article
         * @param Title $requestTitle The original title, before any redirects were applied
         */
        protected function performAction( Article $article, Title $requestTitle ) {
                $request = $this->getRequest();
                $output = $this->getOutput();
                $title = $this->getTitle();
                $user = $this->getUser();

                if ( !$this->getHookRunner()->onMediaWikiPerformAction(
                        $output, $article, $title, $user, $request, $this )
                ) {
                        return;
                }

                $t = microtime( true );
                $actionName = $this->getAction();
                $services = $this->getServiceContainer();

                $action = $services->getActionFactory()->getAction( $actionName, $article, $this->getContext() );
                if ( $action instanceof Action ) {
                        ProfilingContext::singleton()->init( MW_ENTRY_POINT, $actionName );

                        // Check read permissions
                        if ( $action->needsReadRights() && !$user->isAllowed( 'read' ) ) {
                                throw new PermissionsError( 'read' );
                        }

                        // Narrow DB query expectations for this HTTP request
                        if ( $request->wasPosted() && !$action->doesWrites() ) {
                                $trxProfiler = Profiler::instance()->getTransactionProfiler();
                                $trxLimits = $this->getConfig( MainConfigNames::TrxProfilerLimits );
                                $trxProfiler->setExpectations( $trxLimits['POST-nonwrite'], __METHOD__ );
                        }

                        // Let CDN cache things if we can purge them.
                        // Also unconditionally cache page views.
                        if ( $this->getConfig( MainConfigNames::UseCdn ) ) {
                                $htmlCacheUpdater = $services->getHtmlCacheUpdater();
                                if ( $request->matchURLForCDN( $htmlCacheUpdater->getUrls( $requestTitle ) ) ) {
                                        $output->setCdnMaxage( $this->getConfig( MainConfigNames::CdnMaxAge ) );
                                } elseif ( $action instanceof ViewAction ) {
                                        $output->setCdnMaxage( 3600 );
                                }
                        }

                        $action->show();

                        $runTime = microtime( true ) - $t;

                        $statAction = strtr( $actionName, '.', '_' );
                        $services->getStatsFactory()->getTiming( 'action_executeTiming_seconds' )
                                ->setLabel( 'action', $statAction )
                                ->copyToStatsdAt( 'action.' . $statAction . '.executeTiming' )
                                ->observe( 1000 * $runTime );

                        return;
                }

                // If we've not found out which action it is by now, it's unknown
                $output->setStatusCode( 404 );
                $output->showErrorPage( 'nosuchaction', 'nosuchactiontext' );
        }
}