图片附件防盗链

function showattachment()
    {
        global $DB, $forums, $_INPUT, $bbuserinfo, $bboptions;
        $forums->noheader = 1;
        $filename = $_INPUT['filename'];
        $extension = $_INPUT['extension'];
        $update=TRUE;
        $url=parse_url($_SERVER['HTTP_REFERER']);
        if ($url['host']!=$_SERVER['HTTP_HOST'] AND in_array($forums->cache['attachmenttype'][ $extension ]['mimetype'], array( 'gif', 'jpeg', 'jpg', 'png' ))) {
            $filename = 'mypic.gif'; //在这里填写你的URL地址
            $extension = $av_ext = preg_replace( "/^.*.(S+)$/", "1", $filename );
            $files = $bboptions['uploadfolder'].'/'.$filename;
            $noupdate=FALSE;
        } else {
            if (!$_INPUT['u'] OR !$_INPUT['attach']) {
                $forums->func->standard_error("cannotviewattach");
            }
            if (!$bbuserinfo['candownload']) {
                $forums->func->standard_error("cannotdownload");
            }
            $subpath = SAFE_MODE ? "" : implode('/', preg_split('//', intval($_INPUT['u']),  -1, PREG_SPLIT_NO_EMPTY));
            $subpath = trim($_INPUT['attachpath']) ? $subpath : '';
            $path = $bboptions['uploadfolder'] . '/' . $subpath;
            $_INPUT['attach'] = str_replace( "/", "", substr( $_INPUT['attach'], strrpos( $_INPUT['attach'], '/' ) ) );
            $files = "e:/www/mxb/data/uploads/mypic.gif";
        }
        if ( file_exists( $files ) AND ( $forums->cache['attachmenttype'][ $extension ]['mimetype'] != "" ) ) {
            if($update) {
                $DB->shutdown_query("UPDATE ".TABLE_PREFIX."attachment SET counter=counter+1 WHERE attachmentid=".intval($_INPUT['id'])."");
            }
            @header('Cache-control: max-age=31536000');
            @header('Expires: ' . gmdate("D, d M Y H:i:s", TIMENOW + 31536000) . ' GMT');
            @header( 'Content-Type: '.$forums->cache['attachmenttype'][ $extension ]['mimetype'].'' );
            @header( 'Content-Disposition: inline; filename='.$filename.'' );
            @header( 'Content-Disposition: inline; filename='.$filename.'' );
            @header( 'Content-Length: '.(string)(filesize( $files ) ).'' );
            $fh = fopen( $files, 'rb' );
            fpassthru( $fh );
            @fclose( $fh );
            exit();
        } else {
            $forums->func->standard_error("cannotviewattach");
        }
    }