includes/OutputHandler.php

   1 <?php
   2
   3 /**
   4  * Standard output handler for use with ob_start
   5  */
   6 function wfOutputHandler( $s ) {
   7         global $wgDisableOutputCompression;
   8         $s = wfMangleFlashPolicy( $s );
   9         if ( !$wgDisableOutputCompression && !ini_get( 'zlib.output_compression' ) ) {
  10                 if ( !defined( 'MW_NO_OUTPUT_COMPRESSION' ) ) {
  11                         $s = wfGzipHandler( $s );
  12                 }
  13                 if ( !ini_get( 'output_handler' ) ) {
  14                         wfDoContentLength( strlen( $s ) );
  15                 }
  16         }
  17         return $s;
  18 }
  19
  20 /**
  21  * Get the "file extension" that some client apps will estimate from
  22  * the currently-requested URL.
  23  * This isn't on WebRequest because we need it when things aren't initialized
  24  * @private
  25  */
  26 function wfRequestExtension() {
  27         /// @fixme -- this sort of dupes some code in WebRequest::getRequestUrl()
  28         if( isset( $_SERVER['REQUEST_URI'] ) ) {
  29                 // Strip the query string...
  30                 list( $path ) = explode( '?', $_SERVER['REQUEST_URI'], 2 );
  31         } elseif( isset( $_SERVER['SCRIPT_NAME'] ) ) {
  32                 // Probably IIS. QUERY_STRING appears separately.
  33                 $path = $_SERVER['SCRIPT_NAME'];
  34         } else {
  35                 // Can't get the path from the server? :(
  36                 return '';
  37         }
  38
  39         $period = strrpos( $path, '.' );
  40         if( $period !== false ) {
  41                 return strtolower( substr( $path, $period ) );
  42         }
  43         return '';
  44 }
  45
  46 /**
  47  * Handler that compresses data with gzip if allowed by the Accept header.
  48  * Unlike ob_gzhandler, it works for HEAD requests too.
  49  */
  50 function wfGzipHandler( $s ) {
  51         if( !function_exists( 'gzencode' ) || headers_sent() ) {
  52                 return $s;
  53         }
  54
  55         $ext = wfRequestExtension();
  56         if( $ext == '.gz' || $ext == '.tgz' ) {
  57                 // Don't do gzip compression if the URL path ends in .gz or .tgz
  58                 // This confuses Safari and triggers a download of the page,
  59                 // even though it's pretty clearly labeled as viewable HTML.
  60                 // Bad Safari! Bad!
  61                 return $s;
  62         }
  63
  64         if( isset( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ) {
  65                 $tokens = preg_split( '/[,; ]/', $_SERVER['HTTP_ACCEPT_ENCODING'] );
  66                 if ( in_array( 'gzip', $tokens ) ) {
  67                         header( 'Content-Encoding: gzip' );
  68                         $s = gzencode( $s, 3 );
  69                 }
  70         }
  71
  72         // Set vary header if it hasn't been set already
  73         $headers = headers_list();
  74         $foundVary = false;
  75         foreach ( $headers as $header ) {
  76                 if ( substr( $header, 0, 5 ) == 'Vary:' ) {
  77                         $foundVary = true;
  78                         break;
  79                 }
  80         }
  81         if ( !$foundVary ) {
  82                 header( 'Vary: Accept-Encoding' );
  83                 header( 'X-Vary-Options: Accept-Encoding;list-contains=gzip' );
  84         }
  85         return $s;
  86 }
  87
  88 /**
  89  * Mangle flash policy tags which open up the site to XSS attacks.
  90  */
  91 function wfMangleFlashPolicy( $s ) {
  92         return preg_replace( '/\<\s*cross-domain-policy\s*\>/i', '<NOT-cross-domain-policy>', $s );
  93 }
  94
  95 /**
  96  * Add a Content-Length header if possible. This makes it cooperate with squid better.
  97  */
  98 function wfDoContentLength( $length ) {
  99         if ( !headers_sent() && $_SERVER['SERVER_PROTOCOL'] == 'HTTP/1.0' ) {
 100                 header( "Content-Length: $length" );
 101         }
 102 }
 103
 104