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  * @return string
  12  */
  13 function wfOutputHandler( $s ) {
  14         global $wgDisableOutputCompression, $wgValidateAllHtml;
  15         $s = wfMangleFlashPolicy( $s );
  16         if ( $wgValidateAllHtml ) {
  17                 $headers = apache_response_headers();
  18                 $isHTML = true;
  19                 foreach ( $headers as $name => $value ) {
  20                         if ( strtolower( $name ) == 'content-type' && strpos( $value, 'text/html' ) === false && strpos( $value, 'application/xhtml+xml' ) === false ) {
  21                                 $isHTML = false;
  22                                 break;
  23                         }
  24                 }
  25                 if ( $isHTML ) {
  26                         $s = wfHtmlValidationHandler( $s );
  27                 }
  28         }
  29         if ( !$wgDisableOutputCompression && !ini_get( 'zlib.output_compression' ) ) {
  30                 if ( !defined( 'MW_NO_OUTPUT_COMPRESSION' ) ) {
  31                         $s = wfGzipHandler( $s );
  32                 }
  33                 if ( !ini_get( 'output_handler' ) ) {
  34                         wfDoContentLength( strlen( $s ) );
  35                 }
  36         }
  37         return $s;
  38 }
  39
  40 /**
  41  * Get the "file extension" that some client apps will estimate from
  42  * the currently-requested URL.
  43  * This isn't on WebRequest because we need it when things aren't initialized
  44  * @private
  45  *
  46  * @return string
  47  */
  48 function wfRequestExtension() {
  49         /// @todo FIXME: this sort of dupes some code in WebRequest::getRequestUrl()
  50         if( isset( $_SERVER['REQUEST_URI'] ) ) {
  51                 // Strip the query string...
  52                 list( $path ) = explode( '?', $_SERVER['REQUEST_URI'], 2 );
  53         } elseif( isset( $_SERVER['SCRIPT_NAME'] ) ) {
  54                 // Probably IIS. QUERY_STRING appears separately.
  55                 $path = $_SERVER['SCRIPT_NAME'];
  56         } else {
  57                 // Can't get the path from the server? :(
  58                 return '';
  59         }
  60
  61         $period = strrpos( $path, '.' );
  62         if( $period !== false ) {
  63                 return strtolower( substr( $path, $period ) );
  64         }
  65         return '';
  66 }
  67
  68 /**
  69  * Handler that compresses data with gzip if allowed by the Accept header.
  70  * Unlike ob_gzhandler, it works for HEAD requests too.
  71  *
  72  * @param $s string
  73  *
  74  * @return string
  75  */
  76 function wfGzipHandler( $s ) {
  77         if( !function_exists( 'gzencode' ) || headers_sent() ) {
  78                 return $s;
  79         }
  80
  81         $ext = wfRequestExtension();
  82         if( $ext == '.gz' || $ext == '.tgz' ) {
  83                 // Don't do gzip compression if the URL path ends in .gz or .tgz
  84                 // This confuses Safari and triggers a download of the page,
  85                 // even though it's pretty clearly labeled as viewable HTML.
  86                 // Bad Safari! Bad!
  87                 return $s;
  88         }
  89
  90         if( wfClientAcceptsGzip() ) {
  91                 header( 'Content-Encoding: gzip' );
  92                 $s = gzencode( $s, 6 );
  93         }
  94
  95         // Set vary header if it hasn't been set already
  96         $headers = headers_list();
  97         $foundVary = false;
  98         foreach ( $headers as $header ) {
  99                 if ( substr( $header, 0, 5 ) == 'Vary:' ) {
 100                         $foundVary = true;
 101                         break;
 102                 }
 103         }
 104         if ( !$foundVary ) {
 105                 header( 'Vary: Accept-Encoding' );
 106                 global $wgUseXVO;
 107                 if ( $wgUseXVO ) {
 108                         header( 'X-Vary-Options: Accept-Encoding;list-contains=gzip' );
 109                 }
 110         }
 111         return $s;
 112 }
 113
 114 /**
 115  * Mangle flash policy tags which open up the site to XSS attacks.
 116  *
 117  * @param $s string
 118  *
 119  * @return string
 120  */
 121 function wfMangleFlashPolicy( $s ) {
 122         # Avoid weird excessive memory usage in PCRE on big articles
 123         if ( preg_match( '/\<\s*cross-domain-policy\s*\>/i', $s ) ) {
 124                 return preg_replace( '/\<\s*cross-domain-policy\s*\>/i', '<NOT-cross-domain-policy>', $s );
 125         } else {
 126                 return $s;
 127         }
 128 }
 129
 130 /**
 131  * Add a Content-Length header if possible. This makes it cooperate with squid better.
 132  *
 133  * @param $length int
 134  */
 135 function wfDoContentLength( $length ) {
 136         if ( !headers_sent() && $_SERVER['SERVER_PROTOCOL'] == 'HTTP/1.0' ) {
 137                 header( "Content-Length: $length" );
 138         }
 139 }
 140
 141 /**
 142  * Replace the output with an error if the HTML is not valid
 143  *
 144  * @param $s string
 145  *
 146  * @return string
 147  */
 148 function wfHtmlValidationHandler( $s ) {
 149
 150         $errors = '';
 151         if ( MWTidy::checkErrors( $s, $errors ) ) {
 152                 return $s;
 153         }
 154
 155         header( 'Cache-Control: no-cache' );
 156
 157         $out = <<<EOT
 158 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 159 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" dir="ltr">
 160 <head>
 161 <title>HTML validation error</title>
 162 <style>
 163 .highlight { background-color: #ffc }
 164 li { white-space: pre }
 165 </style>
 166 </head>
 167 <body>
 168 <h1>HTML validation error</h1>
 169 <ul>
 170 EOT;
 171
 172         $error = strtok( $errors, "\n" );
 173         $badLines = array();
 174         while ( $error !== false ) {
 175                 if ( preg_match( '/^line (\d+)/', $error, $m ) ) {
 176                         $lineNum = intval( $m[1] );
 177                         $badLines[$lineNum] = true;
 178                         $out .= "<li><a href=\"#line-{$lineNum}\">" . htmlspecialchars( $error ) . "</a></li>\n";
 179                 }
 180                 $error = strtok( "\n" );
 181         }
 182
 183         $out .= '</ul>';
 184         $out .= '<pre>' . htmlspecialchars( $errors ) . '</pre>';
 185         $out .= "<ol>\n";
 186         $line = strtok( $s, "\n" );
 187         $i = 1;
 188         while ( $line !== false ) {
 189                 if ( isset( $badLines[$i] ) ) {
 190                         $out .= "<li class=\"highlight\" id=\"line-$i\">";
 191                 } else {
 192                         $out .= '<li>';
 193                 }
 194                 $out .= htmlspecialchars( $line ) . "</li>\n";
 195                 $line = strtok( "\n" );
 196                 $i++;
 197         }
 198         $out .= '</ol></body></html>';
 199         return $out;
 200 }