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