function advagg_add_dns_prefetch in Advanced CSS/JS Aggregation 7.2

Add in the dns-prefetch header for CSS and JS external files.

Parameters

string $url: The url of the external host.

Return value

bool TRUE if it was added to the head.

3 calls to advagg_add_dns_prefetch()

advagg_add_resource_hints_array in ./advagg.module

Find dns_prefetch and call advagg_add_dns_prefetch().

advagg_mod_page_alter in advagg_mod/advagg_mod.module

Implements hook_page_alter().

advagg_mod_xpath_script_external_dns in advagg_mod/advagg_mod.module

Use DOMDocument's loadHTML along with DOMXPath's query to find script tags.

File

./advagg.module, line 2597

Advanced CSS/JS aggregation module.

Code

function advagg_add_dns_prefetch($url) {

  // Keep the order.
  $advagg_resource_hints_location = variable_get('advagg_resource_hints_location', ADVAGG_RESOURCE_HINTS_LOCATION);
  static $weight = -1001;
  if ($advagg_resource_hints_location == 3) {
    $weight = -999.9;
  }
  $weight += 0.0001;

  // Get the host.
  $parse = @parse_url($url);
  if (empty($parse['host'])) {

    // If just the hostname was given, build proper url.
    if (strpos($url, '.') && strpos($url, '/') === FALSE) {
      $parse['scheme'] = '//';
      $parse['host'] = $url;

      // Check for fragment.
      $pos = strpos($url, '#');
      if ($pos !== FALSE) {
        $parse['fragment'] = substr($url, $pos + 1);
        $parse['host'] = substr($url, 0, $pos);
      }

      // Put it back together and parse again.
      $url = advagg_glue_url($parse);
      $parse = @parse_url($url);
    }
    if (empty($parse['host'])) {
      return FALSE;
    }
  }

  // Filter out wrong schemes.
  if (!empty($parse['scheme']) && $parse['scheme'] !== 'http' && $parse['scheme'] !== 'https') {
    return FALSE;
  }

  // Filter out local host.
  $host = @parse_url($GLOBALS['base_root'], PHP_URL_HOST);
  if ($parse['host'] === $host) {
    return FALSE;
  }

  // Add DNS information for more domains.
  if (strpos($parse['host'], 'fonts.googleapis.com') !== FALSE) {

    // Add fonts.gstatic.com when fonts.googleapis.com is added.
    advagg_add_dns_prefetch('https://fonts.gstatic.com/#crossorigin');
  }

  // Build render array.
  if (variable_get('advagg_resource_hints_dns_prefetch', ADVAGG_RESOURCE_HINTS_DNS_PREFETCH)) {
    $element = array(
      '#type' => 'html_tag',
      '#tag' => 'link',
      '#attributes' => array(
        'rel' => 'dns-prefetch',
        'href' => '//' . $parse['host'],
      ),
      '#weight' => $weight,
    );

    // Add markup for dns-prefetch to html_head.
    drupal_add_html_head($element, 'advagg_resource_hints_dns_prefetch:' . $parse['host']);
  }
  if (variable_get('advagg_resource_hints_preconnect', ADVAGG_RESOURCE_HINTS_PRECONNECT)) {

    // HTTPS use Protocol Relative; HTTP and scheme defined use given scheme.
    $href = '//' . $parse['host'];
    if (!$GLOBALS['is_https'] && isset($parse['scheme'])) {
      $href = "{$parse['scheme']}://{$parse['host']}";
    }
    $element = array(
      '#type' => 'html_tag',
      '#tag' => 'link',
      '#attributes' => array(
        'rel' => 'preconnect',
        'href' => $href,
      ),
      '#weight' => $weight,
    );
    if (!empty($parse['fragment']) && $parse['fragment'] === 'crossorigin') {
      $element['#attributes']['crossorigin'] = '';
    }

    // Add markup for dns-prefetch to html_head.
    drupal_add_html_head($element, 'advagg_resource_hints_preconnect:' . $parse['host']);
  }

  // Build render array. Goes after charset tag.
  if (!empty($parse['fragment']) && $parse['fragment'] === 'prefetch') {

    // Hacky way to open up a connection to the remote host.
    $element = array(
      '#type' => 'html_tag',
      '#tag' => 'link',
      '#attributes' => array(
        'rel' => 'prefetch',
        'href' => '//' . $parse['host'] . '/robots.txt',
      ),
      '#weight' => $weight,
    );
    drupal_add_html_head($element, 'advagg_prefetch:' . $parse['host']);
  }
  return TRUE;
}