includes/StreamFile.php

   1 <?php
   2 /**
   3  * Functions related to the output of file content
   4  *
   5  * @file
   6  */
   7 class StreamFile {
   8         const READY_STREAM = 1;
   9         const NOT_MODIFIED = 2;
  10
  11         /**
  12          * Stream a file to the browser, adding all the headings and fun stuff.
  13          * Headers sent include: Content-type, Content-Length, Last-Modified,
  14          * and Content-Disposition.
  15          *
  16          * @param $fname string Full name and path of the file to stream
  17          * @param $headers array Any additional headers to send
  18          * @param $sendErrors bool Send error messages if errors occur (like 404)
  19          * @return bool Success
  20          */
  21         public static function stream( $fname, $headers = array(), $sendErrors = true ) {
  22                 wfProfileIn( __METHOD__ );
  23
  24                 wfSuppressWarnings();
  25                 $stat = stat( $fname );
  26                 wfRestoreWarnings();
  27
  28                 $res = self::prepareForStream( $fname, $stat, $headers, $sendErrors );
  29                 if ( $res == self::NOT_MODIFIED ) {
  30                         $ok = true; // use client cache
  31                 } elseif ( $res == self::READY_STREAM ) {
  32                         $ok = readfile( $fname );
  33                 } else {
  34                         $ok = false; // failed
  35                 }
  36
  37                 wfProfileOut( __METHOD__ );
  38                 return $ok;
  39         }
  40
  41         /**
  42          * Call this function used in preparation before streaming a file.
  43          * This function does the following:
  44          * (a) sends Last-Modified, Content-type, and Content-Disposition headers
  45          * (b) cancels any PHP output buffering and automatic gzipping of output
  46          * (c) sends Content-Length header based on HTTP_IF_MODIFIED_SINCE check
  47          *
  48          * @param $path string Storage path or file system path
  49          * @param $info Array|bool File stat info with 'mtime' and 'size' fields
  50          * @param $headers Array Additional headers to send
  51          * @param $sendErrors bool Send error messages if errors occur (like 404)
  52          * @return int|bool READY_STREAM, NOT_MODIFIED, or false on failure
  53          */
  54         public static function prepareForStream(
  55                 $path, $info, $headers = array(), $sendErrors = true
  56         ) {
  57                 global $wgLanguageCode;
  58
  59                 if ( !is_array( $info ) ) {
  60                         if ( $sendErrors ) {
  61                                 header( 'HTTP/1.0 404 Not Found' );
  62                                 header( 'Cache-Control: no-cache' );
  63                                 header( 'Content-Type: text/html; charset=utf-8' );
  64                                 $encFile = htmlspecialchars( $path );
  65                                 $encScript = htmlspecialchars( $_SERVER['SCRIPT_NAME'] );
  66                                 echo "<html><body>
  67                                         <h1>File not found</h1>
  68                                         <p>Although this PHP script ($encScript) exists, the file requested for output
  69                                         ($encFile) does not.</p>
  70                                         </body></html>
  71                                         ";
  72                         }
  73                         return false;
  74                 }
  75
  76                 // Sent Last-Modified HTTP header for client-side caching
  77                 header( 'Last-Modified: ' . wfTimestamp( TS_RFC2822, $info['mtime'] ) );
  78
  79                 // Cancel output buffering and gzipping if set
  80                 wfResetOutputBuffers();
  81
  82                 $type = self::contentTypeFromPath( $path );
  83                 if ( $type && $type != 'unknown/unknown' ) {
  84                         header( "Content-type: $type" );
  85                 } else {
  86                         // Send a content type which is not known to Internet Explorer, to
  87                         // avoid triggering IE's content type detection. Sending a standard
  88                         // unknown content type here essentially gives IE license to apply
  89                         // whatever content type it likes.
  90                         header( 'Content-type: application/x-wiki' );
  91                 }
  92
  93                 // Don't stream it out as text/html if there was a PHP error
  94                 if ( headers_sent() ) {
  95                         echo "Headers already sent, terminating.\n";
  96                         return false;
  97                 }
  98
  99                 header( "Content-Disposition: inline;filename*=utf-8'$wgLanguageCode'" .
 100                         urlencode( basename( $path ) ) );
 101
 102                 // Send additional headers
 103                 foreach ( $headers as $header ) {
 104                         header( $header );
 105                 }
 106
 107                 // Don't send if client has up to date cache
 108                 if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
 109                         $modsince = preg_replace( '/;.*$/', '', $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
 110                         if ( wfTimestamp( TS_UNIX, $info['mtime'] ) <= strtotime( $modsince ) ) {
 111                                 ini_set( 'zlib.output_compression', 0 );
 112                                 header( "HTTP/1.0 304 Not Modified" );
 113                                 return self::NOT_MODIFIED; // ok
 114                         }
 115                 }
 116
 117                 header( 'Content-Length: ' . $info['size'] );
 118
 119                 return self::READY_STREAM; // ok
 120         }
 121
 122         /**
 123          * Determine the file type of a file based on the path
 124          *
 125          * @param $filename string Storage path or file system path
 126          * @param $safe bool Whether to do retroactive upload blacklist checks
 127          * @return null|string
 128          */
 129         public static function contentTypeFromPath( $filename, $safe = true ) {
 130                 global $wgTrivialMimeDetection;
 131
 132                 $ext = strrchr( $filename, '.' );
 133                 $ext = $ext === false ? '' : strtolower( substr( $ext, 1 ) );
 134
 135                 # trivial detection by file extension,
 136                 # used for thumbnails (thumb.php)
 137                 if ( $wgTrivialMimeDetection ) {
 138                         switch ( $ext ) {
 139                                 case 'gif': return 'image/gif';
 140                                 case 'png': return 'image/png';
 141                                 case 'jpg': return 'image/jpeg';
 142                                 case 'jpeg': return 'image/jpeg';
 143                         }
 144
 145                         return 'unknown/unknown';
 146                 }
 147
 148                 $magic = MimeMagic::singleton();
 149                 // Use the extension only, rather than magic numbers, to avoid opening
 150                 // up vulnerabilities due to uploads of files with allowed extensions
 151                 // but disallowed types.
 152                 $type = $magic->guessTypesForExtension( $ext );
 153
 154                 /**
 155                  * Double-check some security settings that were done on upload but might
 156                  * have changed since.
 157                  */
 158                 if ( $safe ) {
 159                         global $wgFileBlacklist, $wgCheckFileExtensions, $wgStrictFileExtensions,
 160                                 $wgFileExtensions, $wgVerifyMimeType, $wgMimeTypeBlacklist;
 161                         list( , $extList ) = UploadBase::splitExtensions( $filename );
 162                         if ( UploadBase::checkFileExtensionList( $extList, $wgFileBlacklist ) ) {
 163                                 return 'unknown/unknown';
 164                         }
 165                         if ( $wgCheckFileExtensions && $wgStrictFileExtensions
 166                                 && !UploadBase::checkFileExtensionList( $extList, $wgFileExtensions ) )
 167                         {
 168                                 return 'unknown/unknown';
 169                         }
 170                         if ( $wgVerifyMimeType && in_array( strtolower( $type ), $wgMimeTypeBlacklist ) ) {
 171                                 return 'unknown/unknown';
 172                         }
 173                 }
 174                 return $type;
 175         }
 176 }