includes/StreamFile.php

   1 <?php
   2 /**
   3  * Functions related to the output of file content.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * Functions related to the output of file content
  25  */
  26 class StreamFile {
  27         const READY_STREAM = 1;
  28         const NOT_MODIFIED = 2;
  29
  30         /**
  31          * Stream a file to the browser, adding all the headings and fun stuff.
  32          * Headers sent include: Content-type, Content-Length, Last-Modified,
  33          * and Content-Disposition.
  34          *
  35          * @param string $fname Full name and path of the file to stream
  36          * @param array $headers Any additional headers to send
  37          * @param bool $sendErrors Send error messages if errors occur (like 404)
  38          * @throws MWException
  39          * @return bool Success
  40          */
  41         public static function stream( $fname, $headers = array(), $sendErrors = true ) {
  42                 wfProfileIn( __METHOD__ );
  43
  44                 if ( FileBackend::isStoragePath( $fname ) ) { // sanity
  45                         wfProfileOut( __METHOD__ );
  46                         throw new MWException( __FUNCTION__ . " given storage path '$fname'." );
  47                 }
  48
  49                 wfSuppressWarnings();
  50                 $stat = stat( $fname );
  51                 wfRestoreWarnings();
  52
  53                 $res = self::prepareForStream( $fname, $stat, $headers, $sendErrors );
  54                 if ( $res == self::NOT_MODIFIED ) {
  55                         $ok = true; // use client cache
  56                 } elseif ( $res == self::READY_STREAM ) {
  57                         wfProfileIn( __METHOD__ . '-send' );
  58                         $ok = readfile( $fname );
  59                         wfProfileOut( __METHOD__ . '-send' );
  60                 } else {
  61                         $ok = false; // failed
  62                 }
  63
  64                 wfProfileOut( __METHOD__ );
  65                 return $ok;
  66         }
  67
  68         /**
  69          * Call this function used in preparation before streaming a file.
  70          * This function does the following:
  71          * (a) sends Last-Modified, Content-type, and Content-Disposition headers
  72          * (b) cancels any PHP output buffering and automatic gzipping of output
  73          * (c) sends Content-Length header based on HTTP_IF_MODIFIED_SINCE check
  74          *
  75          * @param string $path Storage path or file system path
  76          * @param array|bool $info File stat info with 'mtime' and 'size' fields
  77          * @param array $headers Additional headers to send
  78          * @param bool $sendErrors Send error messages if errors occur (like 404)
  79          * @return int|bool READY_STREAM, NOT_MODIFIED, or false on failure
  80          */
  81         public static function prepareForStream(
  82                 $path, $info, $headers = array(), $sendErrors = true
  83         ) {
  84                 if ( !is_array( $info ) ) {
  85                         if ( $sendErrors ) {
  86                                 header( 'HTTP/1.0 404 Not Found' );
  87                                 header( 'Cache-Control: no-cache' );
  88                                 header( 'Content-Type: text/html; charset=utf-8' );
  89                                 $encFile = htmlspecialchars( $path );
  90                                 $encScript = htmlspecialchars( $_SERVER['SCRIPT_NAME'] );
  91                                 echo "<html><body>
  92                                         <h1>File not found</h1>
  93                                         <p>Although this PHP script ($encScript) exists, the file requested for output
  94                                         ($encFile) does not.</p>
  95                                         </body></html>
  96                                         ";
  97                         }
  98                         return false;
  99                 }
 100
 101                 // Sent Last-Modified HTTP header for client-side caching
 102                 header( 'Last-Modified: ' . wfTimestamp( TS_RFC2822, $info['mtime'] ) );
 103
 104                 // Cancel output buffering and gzipping if set
 105                 wfResetOutputBuffers();
 106
 107                 $type = self::contentTypeFromPath( $path );
 108                 if ( $type && $type != 'unknown/unknown' ) {
 109                         header( "Content-type: $type" );
 110                 } else {
 111                         // Send a content type which is not known to Internet Explorer, to
 112                         // avoid triggering IE's content type detection. Sending a standard
 113                         // unknown content type here essentially gives IE license to apply
 114                         // whatever content type it likes.
 115                         header( 'Content-type: application/x-wiki' );
 116                 }
 117
 118                 // Don't stream it out as text/html if there was a PHP error
 119                 if ( headers_sent() ) {
 120                         echo "Headers already sent, terminating.\n";
 121                         return false;
 122                 }
 123
 124                 // Send additional headers
 125                 foreach ( $headers as $header ) {
 126                         header( $header );
 127                 }
 128
 129                 // Don't send if client has up to date cache
 130                 if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
 131                         $modsince = preg_replace( '/;.*$/', '', $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
 132                         if ( wfTimestamp( TS_UNIX, $info['mtime'] ) <= strtotime( $modsince ) ) {
 133                                 ini_set( 'zlib.output_compression', 0 );
 134                                 header( "HTTP/1.0 304 Not Modified" );
 135                                 return self::NOT_MODIFIED; // ok
 136                         }
 137                 }
 138
 139                 header( 'Content-Length: ' . $info['size'] );
 140
 141                 return self::READY_STREAM; // ok
 142         }
 143
 144         /**
 145          * Determine the file type of a file based on the path
 146          *
 147          * @param string $filename Storage path or file system path
 148          * @param bool $safe Whether to do retroactive upload blacklist checks
 149          * @return null|string
 150          */
 151         public static function contentTypeFromPath( $filename, $safe = true ) {
 152                 global $wgTrivialMimeDetection;
 153
 154                 $ext = strrchr( $filename, '.' );
 155                 $ext = $ext === false ? '' : strtolower( substr( $ext, 1 ) );
 156
 157                 # trivial detection by file extension,
 158                 # used for thumbnails (thumb.php)
 159                 if ( $wgTrivialMimeDetection ) {
 160                         switch ( $ext ) {
 161                                 case 'gif':
 162                                         return 'image/gif';
 163                                 case 'png':
 164                                         return 'image/png';
 165                                 case 'jpg':
 166                                         return 'image/jpeg';
 167                                 case 'jpeg':
 168                                         return 'image/jpeg';
 169                         }
 170
 171                         return 'unknown/unknown';
 172                 }
 173
 174                 $magic = MimeMagic::singleton();
 175                 // Use the extension only, rather than magic numbers, to avoid opening
 176                 // up vulnerabilities due to uploads of files with allowed extensions
 177                 // but disallowed types.
 178                 $type = $magic->guessTypesForExtension( $ext );
 179
 180                 /**
 181                  * Double-check some security settings that were done on upload but might
 182                  * have changed since.
 183                  */
 184                 if ( $safe ) {
 185                         global $wgFileBlacklist, $wgCheckFileExtensions, $wgStrictFileExtensions,
 186                                 $wgFileExtensions, $wgVerifyMimeType, $wgMimeTypeBlacklist;
 187                         list( , $extList ) = UploadBase::splitExtensions( $filename );
 188                         if ( UploadBase::checkFileExtensionList( $extList, $wgFileBlacklist ) ) {
 189                                 return 'unknown/unknown';
 190                         }
 191                         if ( $wgCheckFileExtensions && $wgStrictFileExtensions
 192                                 && !UploadBase::checkFileExtensionList( $extList, $wgFileExtensions )
 193                         ) {
 194                                 return 'unknown/unknown';
 195                         }
 196                         if ( $wgVerifyMimeType && in_array( strtolower( $type ), $wgMimeTypeBlacklist ) ) {
 197                                 return 'unknown/unknown';
 198                         }
 199                 }
 200                 return $type;
 201         }
 202 }