wikimedia/mediawiki-core

<?php

/**
 * Functions related to the output of file content.
 *
 * 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
 */

namespace MediaWiki\Output;

use HTTPFileStreamer;
use InvalidArgumentException;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use RequestContext;
use UploadBase;
use Wikimedia\FileBackend\FileBackend;

/**
 * Functions related to the output of file content
 */
class StreamFile {
    /** @var string */
    private const UNKNOWN_CONTENT_TYPE = 'unknown/unknown';

    /**
     * Stream a file to the browser, adding all the headings and fun stuff.
     * Headers sent include: Content-type, Content-Length, Last-Modified,
     * and Content-Disposition.
     *
     * @param string $fname Full name and path of the file to stream
     * @param array $headers Any additional headers to send if the file exists
     * @param bool $sendErrors Send error messages if errors occur (like 404)
     * @param array $optHeaders HTTP request header map (e.g. "range") (use lowercase keys)
     * @param int $flags Bitfield of STREAM_* constants
     * @return bool Success
     */
    public static function stream(
        $fname,
        $headers = [],
        $sendErrors = true,
        $optHeaders = [],
        $flags = 0
    ) {
        if ( FileBackend::isStoragePath( $fname ) ) {
            throw new InvalidArgumentException( __FUNCTION__ . " given storage path '$fname'." );
        }

        $streamer = new HTTPFileStreamer(
            $fname,
            [
                'obResetFunc' => 'wfResetOutputBuffers',
                'streamMimeFunc' => [ __CLASS__, 'contentTypeFromPath' ],
                'headerFunc' => [ __CLASS__, 'setHeader' ],
            ]
        );

        return $streamer->stream( $headers, $sendErrors, $optHeaders, $flags );
    }

    /**
     * @param string $header
     *
     * @internal
     */
    public static function setHeader( $header ) {
        RequestContext::getMain()->getRequest()->response()->header( $header );
    }

    /**
     * Determine the file type of a file based on the path
     *
     * @param string $filename Storage path or file system path
     * @param bool $safe Whether to do retroactive upload prevention checks
     * @return null|string
     */
    public static function contentTypeFromPath( $filename, $safe = true ) {
        // NOTE: TrivialMimeDetection is forced by ThumbnailEntryPoint. When this
        // code is moved to a non-static method in a service object, we can no
        // longer rely on that.
        $trivialMimeDetection = MediaWikiServices::getInstance()->getMainConfig()
            ->get( MainConfigNames::TrivialMimeDetection );

        $ext = strrchr( $filename, '.' );
        $ext = $ext ? strtolower( substr( $ext, 1 ) ) : '';

        # trivial detection by file extension,
        # used for thumbnails (thumb.php)
        if ( $trivialMimeDetection ) {
            switch ( $ext ) {
                case 'gif':
                    return 'image/gif';
                case 'png':
                    return 'image/png';
                case 'jpg':
                case 'jpeg':
                    return 'image/jpeg';
            }

            return self::UNKNOWN_CONTENT_TYPE;
        }

        $magic = MediaWikiServices::getInstance()->getMimeAnalyzer();
        // Use the extension only, rather than magic numbers, to avoid opening
        // up vulnerabilities due to uploads of files with allowed extensions
        // but disallowed types.
        $type = $magic->getMimeTypeFromExtensionOrNull( $ext );

        /**
         * Double-check some security settings that were done on upload but might
         * have changed since.
         */
        if ( $safe ) {
            $mainConfig = MediaWikiServices::getInstance()->getMainConfig();
            $prohibitedFileExtensions = $mainConfig->get( MainConfigNames::ProhibitedFileExtensions );
            $checkFileExtensions = $mainConfig->get( MainConfigNames::CheckFileExtensions );
            $strictFileExtensions = $mainConfig->get( MainConfigNames::StrictFileExtensions );
            $fileExtensions = $mainConfig->get( MainConfigNames::FileExtensions );
            $verifyMimeType = $mainConfig->get( MainConfigNames::VerifyMimeType );
            $mimeTypeExclusions = $mainConfig->get( MainConfigNames::MimeTypeExclusions );
            [ , $extList ] = UploadBase::splitExtensions( $filename );
            if ( UploadBase::checkFileExtensionList( $extList, $prohibitedFileExtensions ) ) {
                return self::UNKNOWN_CONTENT_TYPE;
            }
            if (
                $checkFileExtensions &&
                $strictFileExtensions &&
                !UploadBase::checkFileExtensionList( $extList, $fileExtensions )
            ) {
                return self::UNKNOWN_CONTENT_TYPE;
            }
            if ( $verifyMimeType && $type !== null && in_array( strtolower( $type ), $mimeTypeExclusions ) ) {
                return self::UNKNOWN_CONTENT_TYPE;
            }
        }
        return $type;
    }
}

/** @deprecated class alias since 1.41 */
class_alias( StreamFile::class, 'StreamFile' );