includes/OutputHandler.php

   1 <?php
   2 /**
   3  * Functions to be used with PHP's output buffer
   4  *
   5  * @file
   6  */
   7
   8 /**
   9  * Standard output handler for use with ob_start
  10  */
  11 function wfOutputHandler( $s ) {
  12         global $wgDisableOutputCompression, $wgValidateAllHtml;
  13         $s = wfMangleFlashPolicy( $s );
  14         if ( $wgValidateAllHtml ) {
  15                 $headers = apache_response_headers();
  16                 $isHTML = true;
  17                 foreach ( $headers as $name => $value ) {
  18                         if ( strtolower( $name ) == 'content-type' && strpos( $value, 'text/html' ) === false && strpos( $value, 'application/xhtml+xml' ) === false ) {
  19                                 $isHTML = false;
  20                                 break;
  21                         }
  22                 }
  23                 if ( $isHTML ) {
  24                         $s = wfHtmlValidationHandler( $s );
  25                 }
  26         }
  27         if ( !$wgDisableOutputCompression && !ini_get( 'zlib.output_compression' ) ) {
  28                 if ( !defined( 'MW_NO_OUTPUT_COMPRESSION' ) ) {
  29                         $s = wfGzipHandler( $s );
  30                 }
  31                 if ( !ini_get( 'output_handler' ) ) {
  32                         wfDoContentLength( strlen( $s ) );
  33                 }
  34         }
  35         return $s;
  36 }
  37
  38 /**
  39  * Get the "file extension" that some client apps will estimate from
  40  * the currently-requested URL.
  41  * This isn't on WebRequest because we need it when things aren't initialized
  42  * @private
  43  */
  44 function wfRequestExtension() {
  45         /// @todo Fixme: this sort of dupes some code in WebRequest::getRequestUrl()
  46         if( isset( $_SERVER['REQUEST_URI'] ) ) {
  47                 // Strip the query string...
  48                 list( $path ) = explode( '?', $_SERVER['REQUEST_URI'], 2 );
  49         } elseif( isset( $_SERVER['SCRIPT_NAME'] ) ) {
  50                 // Probably IIS. QUERY_STRING appears separately.
  51                 $path = $_SERVER['SCRIPT_NAME'];
  52         } else {
  53                 // Can't get the path from the server? :(
  54                 return '';
  55         }
  56
  57         $period = strrpos( $path, '.' );
  58         if( $period !== false ) {
  59                 return strtolower( substr( $path, $period ) );
  60         }
  61         return '';
  62 }
  63
  64 /**
  65  * Handler that compresses data with gzip if allowed by the Accept header.
  66  * Unlike ob_gzhandler, it works for HEAD requests too.
  67  */
  68 function wfGzipHandler( $s ) {
  69         if( !function_exists( 'gzencode' ) || headers_sent() ) {
  70                 return $s;
  71         }
  72
  73         $ext = wfRequestExtension();
  74         if( $ext == '.gz' || $ext == '.tgz' ) {
  75                 // Don't do gzip compression if the URL path ends in .gz or .tgz
  76                 // This confuses Safari and triggers a download of the page,
  77                 // even though it's pretty clearly labeled as viewable HTML.
  78                 // Bad Safari! Bad!
  79                 return $s;
  80         }
  81
  82         if( wfClientAcceptsGzip() ) {
  83                 header( 'Content-Encoding: gzip' );
  84                 $s = gzencode( $s, 6 );
  85         }
  86
  87         // Set vary header if it hasn't been set already
  88         $headers = headers_list();
  89         $foundVary = false;
  90         foreach ( $headers as $header ) {
  91                 if ( substr( $header, 0, 5 ) == 'Vary:' ) {
  92                         $foundVary = true;
  93                         break;
  94                 }
  95         }
  96         if ( !$foundVary ) {
  97                 header( 'Vary: Accept-Encoding' );
  98                 global $wgUseXVO;
  99                 if ( $wgUseXVO ) {
 100                         header( 'X-Vary-Options: Accept-Encoding;list-contains=gzip' );
 101                 }
 102         }
 103         return $s;
 104 }
 105
 106 /**
 107  * Mangle flash policy tags which open up the site to XSS attacks.
 108  */
 109 function wfMangleFlashPolicy( $s ) {
 110         # Avoid weird excessive memory usage in PCRE on big articles
 111         if ( preg_match( '/\<\s*cross-domain-policy\s*\>/i', $s ) ) {
 112                 return preg_replace( '/\<\s*cross-domain-policy\s*\>/i', '<NOT-cross-domain-policy>', $s );
 113         } else {
 114                 return $s;
 115         }
 116 }
 117
 118 /**
 119  * Add a Content-Length header if possible. This makes it cooperate with squid better.
 120  */
 121 function wfDoContentLength( $length ) {
 122         if ( !headers_sent() && $_SERVER['SERVER_PROTOCOL'] == 'HTTP/1.0' ) {
 123                 header( "Content-Length: $length" );
 124         }
 125 }
 126
 127 /**
 128  * Replace the output with an error if the HTML is not valid
 129  */
 130 function wfHtmlValidationHandler( $s ) {
 131
 132         $errors = '';
 133         if ( MWTidy::checkErrors( $s, $errors ) ) {
 134                 return $s;
 135         }
 136
 137         header( 'Cache-Control: no-cache' );
 138
 139         $out = <<<EOT
 140 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 141 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" dir="ltr">
 142 <head>
 143 <title>HTML validation error</title>
 144 <style>
 145 .highlight { background-color: #ffc }
 146 li { white-space: pre }
 147 </style>
 148 </head>
 149 <body>
 150 <h1>HTML validation error</h1>
 151 <ul>
 152 EOT;
 153
 154         $error = strtok( $errors, "\n" );
 155         $badLines = array();
 156         while ( $error !== false ) {
 157                 if ( preg_match( '/^line (\d+)/', $error, $m ) ) {
 158                         $lineNum = intval( $m[1] );
 159                         $badLines[$lineNum] = true;
 160                         $out .= "<li><a href=\"#line-{$lineNum}\">" . htmlspecialchars( $error ) . "</a></li>\n";
 161                 }
 162                 $error = strtok( "\n" );
 163         }
 164
 165         $out .= '</ul>';
 166         $out .= '<pre>' . htmlspecialchars( $errors ) . '</pre>';
 167         $out .= "<ol>\n";
 168         $line = strtok( $s, "\n" );
 169         $i = 1;
 170         while ( $line !== false ) {
 171                 if ( isset( $badLines[$i] ) ) {
 172                         $out .= "<li class=\"highlight\" id=\"line-$i\">";
 173                 } else {
 174                         $out .= '<li>';
 175                 }
 176                 $out .= htmlspecialchars( $line ) . "</li>\n";
 177                 $line = strtok( "\n" );
 178                 $i++;
 179         }
 180         $out .= '</ol></body></html>';
 181         return $out;
 182 }