OutputHandler.php

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<?php
function wfOutputHandler( $s ) {
        global $wgDisableOutputCompression, $wgValidateAllHtml;
        $s = wfMangleFlashPolicy( $s );
        if ( $wgValidateAllHtml ) {
                $headers = apache_response_headers();
                $isHTML = true;
                foreach ( $headers as $name => $value ) {
                        if ( strtolower( $name ) == 'content-type' && strpos( $value, 'text/html' ) === false && strpos( $value, 'application/xhtml+xml' ) === false ) {
                                $isHTML = false;
                                break;
                        }
                }
                if ( $isHTML ) {
                        $s = wfHtmlValidationHandler( $s );
                }
        }
        if ( !$wgDisableOutputCompression && !ini_get( 'zlib.output_compression' ) ) {
                if ( !defined( 'MW_NO_OUTPUT_COMPRESSION' ) ) {
                        $s = wfGzipHandler( $s );
                }
                if ( !ini_get( 'output_handler' ) ) {
                        wfDoContentLength( strlen( $s ) );
                }
        }
        return $s;
}

function wfRequestExtension() {
        if( isset( $_SERVER['REQUEST_URI'] ) ) {
                // Strip the query string...
                list( $path ) = explode( '?', $_SERVER['REQUEST_URI'], 2 );
        } elseif( isset( $_SERVER['SCRIPT_NAME'] ) ) {
                // Probably IIS. QUERY_STRING appears separately.
                $path = $_SERVER['SCRIPT_NAME'];
        } else {
                // Can't get the path from the server? :(
                return '';
        }

        $period = strrpos( $path, '.' );
        if( $period !== false ) {
                return strtolower( substr( $path, $period ) );
        }
        return '';
}

function wfGzipHandler( $s ) {
        if( !function_exists( 'gzencode' ) ) {
                wfDebug( __FUNCTION__ . "() skipping compression (gzencode unavaible)\n" );
                return $s;
        }
        if( headers_sent() ) {
                wfDebug( __FUNCTION__ . "() skipping compression (headers already sent)\n" );
                return $s;
        }

        $ext = wfRequestExtension();
        if( $ext == '.gz' || $ext == '.tgz' ) {
                // Don't do gzip compression if the URL path ends in .gz or .tgz
                // This confuses Safari and triggers a download of the page,
                // even though it's pretty clearly labeled as viewable HTML.
                // Bad Safari! Bad!
                return $s;
        }

        if( wfClientAcceptsGzip() ) {
                wfDebug( __FUNCTION__ . "() is compressing output\n" );
                header( 'Content-Encoding: gzip' );
                $s = gzencode( $s, 6 );
        }

        // Set vary header if it hasn't been set already
        $headers = headers_list();
        $foundVary = false;
        foreach ( $headers as $header ) {
                if ( substr( $header, 0, 5 ) == 'Vary:' ) {
                        $foundVary = true;
                        break;
                }
        }
        if ( !$foundVary ) {
                header( 'Vary: Accept-Encoding' );
                global $wgUseXVO;
                if ( $wgUseXVO ) {
                        header( 'X-Vary-Options: Accept-Encoding;list-contains=gzip' );
                }
        }
        return $s;
}

function wfMangleFlashPolicy( $s ) {
        # Avoid weird excessive memory usage in PCRE on big articles
        if ( preg_match( '/<\s*cross-domain-policy\s*>/i', $s ) ) {
                return preg_replace( '/<\s*cross-domain-policy\s*>/i', '<NOT-cross-domain-policy>', $s );
        } else {
                return $s;
        }
}

function wfDoContentLength( $length ) {
        if ( !headers_sent() && $_SERVER['SERVER_PROTOCOL'] == 'HTTP/1.0' ) {
                header( "Content-Length: $length" );
        }
}

function wfHtmlValidationHandler( $s ) {

        $errors = '';
        if ( MWTidy::checkErrors( $s, $errors ) ) {
                return $s;
        }

        header( 'Cache-Control: no-cache' );

        $out = <<<EOT
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" dir="ltr">
<head>
<title>HTML validation error</title>
<style>
.highlight { background-color: #ffc }
li { white-space: pre }
</style>
</head>
<body>
<h1>HTML validation error</h1>
<ul>
EOT;

        $error = strtok( $errors, "\n" );
        $badLines = array();
        while ( $error !== false ) {
                if ( preg_match( '/^line (\d+)/', $error, $m ) ) {
                        $lineNum = intval( $m[1] );
                        $badLines[$lineNum] = true;
                        $out .= "<li><a href=\"#line-{$lineNum}\">" . htmlspecialchars( $error ) . "</a></li>\n";
                }
                $error = strtok( "\n" );
        }

        $out .= '</ul>';
        $out .= '<pre>' . htmlspecialchars( $errors ) . '</pre>';
        $out .= "<ol>\n";
        $line = strtok( $s, "\n" );
        $i = 1;
        while ( $line !== false ) {
                if ( isset( $badLines[$i] ) ) {
                        $out .= "<li class=\"highlight\" id=\"line-$i\">";
                } else {
                        $out .= '<li>';
                }
                $out .= htmlspecialchars( $line ) . "</li>\n";
                $line = strtok( "\n" );
                $i++;
        }
        $out .= '</ol></body></html>';
        return $out;
}