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         /// @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( isset( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ) {
  78                 $tokens = preg_split( '/[,; ]/', $_SERVER['HTTP_ACCEPT_ENCODING'] );
  79                 if ( in_array( 'gzip', $tokens ) ) {
  80                         header( 'Content-Encoding: gzip' );
  81                         $s = gzencode( $s, 3 );
  82                 }
  83         }
  84
  85         // Set vary header if it hasn't been set already
  86         $headers = headers_list();
  87         $foundVary = false;
  88         foreach ( $headers as $header ) {
  89                 if ( substr( $header, 0, 5 ) == 'Vary:' ) {
  90                         $foundVary = true;
  91                         break;
  92                 }
  93         }
  94         if ( !$foundVary ) {
  95                 header( 'Vary: Accept-Encoding' );
  96                 header( 'X-Vary-Options: Accept-Encoding;list-contains=gzip' );
  97         }
  98         return $s;
  99 }
 100
 101 /**
 102  * Mangle flash policy tags which open up the site to XSS attacks.
 103  */
 104 function wfMangleFlashPolicy( $s ) {
 105         # Avoid weird excessive memory usage in PCRE on big articles
 106         if ( preg_match( '/\<\s*cross-domain-policy\s*\>/i', $s ) ) {
 107                 return preg_replace( '/\<\s*cross-domain-policy\s*\>/i', '<NOT-cross-domain-policy>', $s );
 108         } else {
 109                 return $s;
 110         }
 111 }
 112
 113 /**
 114  * Add a Content-Length header if possible. This makes it cooperate with squid better.
 115  */
 116 function wfDoContentLength( $length ) {
 117         if ( !headers_sent() && $_SERVER['SERVER_PROTOCOL'] == 'HTTP/1.0' ) {
 118                 header( "Content-Length: $length" );
 119         }
 120 }
 121
 122 /**
 123  * Replace the output with an error if the HTML is not valid
 124  */
 125 function wfHtmlValidationHandler( $s ) {
 126
 127         $errors = '';
 128         if ( MWTidy::checkErrors( $s, $errors ) ) {
 129                 return $s;
 130         }
 131
 132         header( 'Cache-Control: no-cache' );
 133
 134         $out = <<<EOT
 135 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 136 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" dir="ltr">
 137 <head>
 138 <title>HTML validation error</title>
 139 <style>
 140 .highlight { background-color: #ffc }
 141 li { white-space: pre }
 142 </style>
 143 </head>
 144 <body>
 145 <h1>HTML validation error</h1>
 146 <ul>
 147 EOT;
 148
 149         $error = strtok( $errors, "\n" );
 150         $badLines = array();
 151         while ( $error !== false ) {
 152                 if ( preg_match( '/^line (\d+)/', $error, $m ) ) {
 153                         $lineNum = intval( $m[1] );
 154                         $badLines[$lineNum] = true;
 155                         $out .= "<li><a href=\"#line-{$lineNum}\">" . htmlspecialchars( $error ) . "</a></li>\n";
 156                 }
 157                 $error = strtok( "\n" );
 158         }
 159
 160         $out .= '</ul>';
 161         $out .= '<pre>' . htmlspecialchars( $errors ) . '</pre>';
 162         $out .= "<ol>\n";
 163         $line = strtok( $s, "\n" );
 164         $i = 1;
 165         while ( $line !== false ) {
 166                 if ( isset( $badLines[$i] ) ) {
 167                         $out .= "<li class=\"highlight\" id=\"line-$i\">";
 168                 } else {
 169                         $out .= '<li>';
 170                 }
 171                 $out .= htmlspecialchars( $line ) . "</li>\n";
 172                 $line = strtok( "\n" );
 173                 $i++;
 174         }
 175         $out .= '</ol></body></html>';
 176         return $out;
 177 }