function rocket_dns_prefetch($buffer)
{
$dns_link_tags = '';
$cdn_cnames = get_rocket_cdn_cnames(array('all', 'images', 'css_and_js', 'css', 'js'));
// Don't add CNAMES if CDN is disabled HTTPS pages or on specific posts
if (!is_rocket_cdn_on_ssl() || is_rocket_post_excluded_option('cdn')) {
$cdn_cnames = array();
}
$domains = array_merge($cdn_cnames, (array) get_rocket_option('dns_prefetch'));
/**
* Filter list of domains to prefetch DNS
*
* @since 1.1.0
*
* @param array $domains List of domains to prefetch DNS
*/
$domains = apply_filters('rocket_dns_prefetch', $domains);
if (count($domains)) {
foreach ($domains as $domain) {
$dns_link_tags .= '<link rel="dns-prefetch" href="' . esc_url($domain) . '" />';
}
}
// Insert all DNS prefecth tags in head
$buffer = preg_replace('/<head(.*)>/', '<head$1><!--[if IE]><![endif]-->' . $dns_link_tags, $buffer, 1);
return $buffer;
}
function get_rocket_cdn_url($url, $zone = array('all'))
{
$cnames = get_rocket_cdn_cnames($zone);
$wp_content_dirname = ltrim(str_replace(home_url(), '', WP_CONTENT_URL), '/') . '/';
if (defined('DONOTCDN') && DONOTCDN || (int) get_rocket_option('cdn') == 0 || empty($cnames) || !is_rocket_cdn_on_ssl() || is_rocket_post_excluded_option('cdn')) {
return $url;
}
list($host, $path, $scheme, $query) = get_rocket_parse_url($url);
$query = !empty($query) ? '?' . $query : '';
// Exclude rejected & external files from CDN
$rejected_files = get_rocket_cdn_reject_files();
if (!empty($rejected_files) && preg_match('#(' . $rejected_files . ')#', $path) || !empty($scheme) && $host != parse_url(home_url(), PHP_URL_HOST)) {
return $url;
}
if (empty($scheme)) {
// Check if the URL is external
if (strpos($path, $home) === false && !preg_match('#(' . $wp_content_dirname . '|wp-includes)#', $path)) {
return $url;
} else {
$path = str_replace($home, '', ltrim($path, '//'));
}
}
$url = rtrim($cnames[abs(crc32($path)) % count($cnames)], '/') . '/' . ltrim($path, '/') . $query;
$url = rocket_add_url_protocol($url);
return $url;
}