includes/OutputHandler.php

   1 <?php
   2
   3 /**
   4  * Standard output handler for use with ob_start
   5  */
   6 function wfOutputHandler( $s ) {
   7         global $wgDisableOutputCompression, $wgValidateAllHtml;
   8         $s = wfMangleFlashPolicy( $s );
   9         if ( $wgValidateAllHtml ) {
  10                 $headers = apache_response_headers();
  11                 $isHTML = true;
  12                 foreach ( $headers as $name => $value ) {
  13                         if ( strtolower( $name ) == 'content-type' && strpos( $value, 'text/html' ) === false && strpos( $value, 'application/xhtml+xml' ) === false ) {
  14                                 $isHTML = false;
  15                                 break;
  16                         }
  17                 }
  18                 if ( $isHTML ) {
  19                         $s = wfHtmlValidationHandler( $s );
  20                 }
  21         }
  22         if ( !$wgDisableOutputCompression && !ini_get( 'zlib.output_compression' ) ) {
  23                 if ( !defined( 'MW_NO_OUTPUT_COMPRESSION' ) ) {
  24                         $s = wfGzipHandler( $s );
  25                 }
  26                 if ( !ini_get( 'output_handler' ) ) {
  27                         wfDoContentLength( strlen( $s ) );
  28                 }
  29         }
  30         return $s;
  31 }
  32
  33 /**
  34  * Get the "file extension" that some client apps will estimate from
  35  * the currently-requested URL.
  36  * This isn't on WebRequest because we need it when things aren't initialized
  37  * @private
  38  */
  39 function wfRequestExtension() {
  40         /// @todo Fixme: this sort of dupes some code in WebRequest::getRequestUrl()
  41         if( isset( $_SERVER['REQUEST_URI'] ) ) {
  42                 // Strip the query string...
  43                 list( $path ) = explode( '?', $_SERVER['REQUEST_URI'], 2 );
  44         } elseif( isset( $_SERVER['SCRIPT_NAME'] ) ) {
  45                 // Probably IIS. QUERY_STRING appears separately.
  46                 $path = $_SERVER['SCRIPT_NAME'];
  47         } else {
  48                 // Can't get the path from the server? :(
  49                 return '';
  50         }
  51
  52         $period = strrpos( $path, '.' );
  53         if( $period !== false ) {
  54                 return strtolower( substr( $path, $period ) );
  55         }
  56         return '';
  57 }
  58
  59 /**
  60  * Handler that compresses data with gzip if allowed by the Accept header.
  61  * Unlike ob_gzhandler, it works for HEAD requests too.
  62  */
  63 function wfGzipHandler( $s ) {
  64         if( !function_exists( 'gzencode' ) || headers_sent() ) {
  65                 return $s;
  66         }
  67
  68         $ext = wfRequestExtension();
  69         if( $ext == '.gz' || $ext == '.tgz' ) {
  70                 // Don't do gzip compression if the URL path ends in .gz or .tgz
  71                 // This confuses Safari and triggers a download of the page,
  72                 // even though it's pretty clearly labeled as viewable HTML.
  73                 // Bad Safari! Bad!
  74                 return $s;
  75         }
  76
  77         if( wfClientAcceptsGzip() ) {
  78                 header( 'Content-Encoding: gzip' );
  79                 $s = gzencode( $s, 6 );
  80         }
  81
  82         // Set vary header if it hasn't been set already
  83         $headers = headers_list();
  84         $foundVary = false;
  85         foreach ( $headers as $header ) {
  86                 if ( substr( $header, 0, 5 ) == 'Vary:' ) {
  87                         $foundVary = true;
  88                         break;
  89                 }
  90         }
  91         if ( !$foundVary ) {
  92                 header( 'Vary: Accept-Encoding' );
  93                 header( 'X-Vary-Options: Accept-Encoding;list-contains=gzip' );
  94         }
  95         return $s;
  96 }
  97
  98 /**
  99  * Mangle flash policy tags which open up the site to XSS attacks.
 100  */
 101 function wfMangleFlashPolicy( $s ) {
 102         # Avoid weird excessive memory usage in PCRE on big articles
 103         if ( preg_match( '/\<\s*cross-domain-policy\s*\>/i', $s ) ) {
 104                 return preg_replace( '/\<\s*cross-domain-policy\s*\>/i', '<NOT-cross-domain-policy>', $s );
 105         } else {
 106                 return $s;
 107         }
 108 }
 109
 110 /**
 111  * Add a Content-Length header if possible. This makes it cooperate with squid better.
 112  */
 113 function wfDoContentLength( $length ) {
 114         if ( !headers_sent() && $_SERVER['SERVER_PROTOCOL'] == 'HTTP/1.0' ) {
 115                 header( "Content-Length: $length" );
 116         }
 117 }
 118
 119 /**
 120  * Replace the output with an error if the HTML is not valid
 121  */
 122 function wfHtmlValidationHandler( $s ) {
 123
 124         $errors = '';
 125         if ( MWTidy::checkErrors( $s, $errors ) ) {
 126                 return $s;
 127         }
 128
 129         header( 'Cache-Control: no-cache' );
 130
 131         $out = <<<EOT
 132 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 133 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" dir="ltr">
 134 <head>
 135 <title>HTML validation error</title>
 136 <style>
 137 .highlight { background-color: #ffc }
 138 li { white-space: pre }
 139 </style>
 140 </head>
 141 <body>
 142 <h1>HTML validation error</h1>
 143 <ul>
 144 EOT;
 145
 146         $error = strtok( $errors, "\n" );
 147         $badLines = array();
 148         while ( $error !== false ) {
 149                 if ( preg_match( '/^line (\d+)/', $error, $m ) ) {
 150                         $lineNum = intval( $m[1] );
 151                         $badLines[$lineNum] = true;
 152                         $out .= "<li><a href=\"#line-{$lineNum}\">" . htmlspecialchars( $error ) . "</a></li>\n";
 153                 }
 154                 $error = strtok( "\n" );
 155         }
 156
 157         $out .= '</ul>';
 158         $out .= '<pre>' . htmlspecialchars( $errors ) . '</pre>';
 159         $out .= "<ol>\n";
 160         $line = strtok( $s, "\n" );
 161         $i = 1;
 162         while ( $line !== false ) {
 163                 if ( isset( $badLines[$i] ) ) {
 164                         $out .= "<li class=\"highlight\" id=\"line-$i\">";
 165                 } else {
 166                         $out .= '<li>';
 167                 }
 168                 $out .= htmlspecialchars( $line ) . "</li>\n";
 169                 $line = strtok( "\n" );
 170                 $i++;
 171         }
 172         $out .= '</ol></body></html>';
 173         return $out;
 174 }