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                         wfProfileIn( __METHOD__ . '-send' );
  33                         $ok = readfile( $fname );
  34                         wfProfileOut( __METHOD__ . '-send' );
  35                 } else {
  36                         $ok = false; // failed
  37                 }
  38
  39                 wfProfileOut( __METHOD__ );
  40                 return $ok;
  41         }
  42
  43         /**
  44          * Call this function used in preparation before streaming a file.
  45          * This function does the following:
  46          * (a) sends Last-Modified, Content-type, and Content-Disposition headers
  47          * (b) cancels any PHP output buffering and automatic gzipping of output
  48          * (c) sends Content-Length header based on HTTP_IF_MODIFIED_SINCE check
  49          *
  50          * @param $path string Storage path or file system path
  51          * @param $info Array|bool File stat info with 'mtime' and 'size' fields
  52          * @param $headers Array Additional headers to send
  53          * @param $sendErrors bool Send error messages if errors occur (like 404)
  54          * @return int|bool READY_STREAM, NOT_MODIFIED, or false on failure
  55          */
  56         public static function prepareForStream(
  57                 $path, $info, $headers = array(), $sendErrors = true
  58         ) {
  59                 global $wgLanguageCode;
  60
  61                 if ( !is_array( $info ) ) {
  62                         if ( $sendErrors ) {
  63                                 header( 'HTTP/1.0 404 Not Found' );
  64                                 header( 'Cache-Control: no-cache' );
  65                                 header( 'Content-Type: text/html; charset=utf-8' );
  66                                 $encFile = htmlspecialchars( $path );
  67                                 $encScript = htmlspecialchars( $_SERVER['SCRIPT_NAME'] );
  68                                 echo "<html><body>
  69                                         <h1>File not found</h1>
  70                                         <p>Although this PHP script ($encScript) exists, the file requested for output
  71                                         ($encFile) does not.</p>
  72                                         </body></html>
  73                                         ";
  74                         }
  75                         return false;
  76                 }
  77
  78                 // Sent Last-Modified HTTP header for client-side caching
  79                 header( 'Last-Modified: ' . wfTimestamp( TS_RFC2822, $info['mtime'] ) );
  80
  81                 // Cancel output buffering and gzipping if set
  82                 wfResetOutputBuffers();
  83
  84                 $type = self::contentTypeFromPath( $path );
  85                 if ( $type && $type != 'unknown/unknown' ) {
  86                         header( "Content-type: $type" );
  87                 } else {
  88                         // Send a content type which is not known to Internet Explorer, to
  89                         // avoid triggering IE's content type detection. Sending a standard
  90                         // unknown content type here essentially gives IE license to apply
  91                         // whatever content type it likes.
  92                         header( 'Content-type: application/x-wiki' );
  93                 }
  94
  95                 // Don't stream it out as text/html if there was a PHP error
  96                 if ( headers_sent() ) {
  97                         echo "Headers already sent, terminating.\n";
  98                         return false;
  99                 }
 100
 101                 header( "Content-Disposition: inline;filename*=utf-8'$wgLanguageCode'" .
 102                         urlencode( basename( $path ) ) );
 103
 104                 // Send additional headers
 105                 foreach ( $headers as $header ) {
 106                         header( $header );
 107                 }
 108
 109                 // Don't send if client has up to date cache
 110                 if ( !empty( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
 111                         $modsince = preg_replace( '/;.*$/', '', $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
 112                         if ( wfTimestamp( TS_UNIX, $info['mtime'] ) <= strtotime( $modsince ) ) {
 113                                 ini_set( 'zlib.output_compression', 0 );
 114                                 header( "HTTP/1.0 304 Not Modified" );
 115                                 return self::NOT_MODIFIED; // ok
 116                         }
 117                 }
 118
 119                 header( 'Content-Length: ' . $info['size'] );
 120
 121                 return self::READY_STREAM; // ok
 122         }
 123
 124         /**
 125          * Determine the file type of a file based on the path
 126          *
 127          * @param $filename string Storage path or file system path
 128          * @param $safe bool Whether to do retroactive upload blacklist checks
 129          * @return null|string
 130          */
 131         public static function contentTypeFromPath( $filename, $safe = true ) {
 132                 global $wgTrivialMimeDetection;
 133
 134                 $ext = strrchr( $filename, '.' );
 135                 $ext = $ext === false ? '' : strtolower( substr( $ext, 1 ) );
 136
 137                 # trivial detection by file extension,
 138                 # used for thumbnails (thumb.php)
 139                 if ( $wgTrivialMimeDetection ) {
 140                         switch ( $ext ) {
 141                                 case 'gif': return 'image/gif';
 142                                 case 'png': return 'image/png';
 143                                 case 'jpg': return 'image/jpeg';
 144                                 case 'jpeg': return 'image/jpeg';
 145                         }
 146
 147                         return 'unknown/unknown';
 148                 }
 149
 150                 $magic = MimeMagic::singleton();
 151                 // Use the extension only, rather than magic numbers, to avoid opening
 152                 // up vulnerabilities due to uploads of files with allowed extensions
 153                 // but disallowed types.
 154                 $type = $magic->guessTypesForExtension( $ext );
 155
 156                 /**
 157                  * Double-check some security settings that were done on upload but might
 158                  * have changed since.
 159                  */
 160                 if ( $safe ) {
 161                         global $wgFileBlacklist, $wgCheckFileExtensions, $wgStrictFileExtensions,
 162                                 $wgFileExtensions, $wgVerifyMimeType, $wgMimeTypeBlacklist;
 163                         list( , $extList ) = UploadBase::splitExtensions( $filename );
 164                         if ( UploadBase::checkFileExtensionList( $extList, $wgFileBlacklist ) ) {
 165                                 return 'unknown/unknown';
 166                         }
 167                         if ( $wgCheckFileExtensions && $wgStrictFileExtensions
 168                                 && !UploadBase::checkFileExtensionList( $extList, $wgFileExtensions ) )
 169                         {
 170                                 return 'unknown/unknown';
 171                         }
 172                         if ( $wgVerifyMimeType && in_array( strtolower( $type ), $wgMimeTypeBlacklist ) ) {
 173                                 return 'unknown/unknown';
 174                         }
 175                 }
 176                 return $type;
 177         }
 178 }