function backdrop_get_bare_domain

Take a full URL and return only the bare domain, with sub-domains removed.

Parameters

string $url: A fully-qualified URL like https://www.example.co.uk/path-to-page or a partial URL without the protocol, such as www.example.co.uk, as would be provided by $_SERVER['SERVER_NAME'].

Return value

string|FALSE: The bare domain of the starting URL like example.com or example.co.uk.

Related topics

File

core/includes/common.inc, line 559

Common functions that many Backdrop modules will need to reference.

Code

function backdrop_get_bare_domain($url) {
  $parts = parse_url(trim($url, '/'));
  $domain = FALSE;

  // Support full URLs with protocol.
  if (array_key_exists('host', $parts)) {
    $domain = $parts['host'];
  }
  // Partial URLs without protocol.
  elseif (array_key_exists('path', $parts)) {
    // Always remove any trailing path.
    $parts_array = explode('/', $parts['path'], 2);
    $domain = array_shift($parts_array);
  }

  if ($domain) {
    // Always strip off www.
    if (substr($domain, 0, 4) == 'www.') {
      $domain = substr($domain, 3);
    }

    // See what's remaining.
    $sub_parts = explode('.', $domain);
    if (count($sub_parts) > 2) {
      $last = array_pop($sub_parts);
      $second_to_last = array_pop($sub_parts);
      // Likely a country-specific domain like .co.uk.
      if (strlen($last) === 2 && count($sub_parts)) {
        $domain = array_pop($sub_parts) . '.' . $second_to_last . '.' . $last;
      }
      // Either a longer top-level domain such as .com or a short domain with
      // no sub-domains (other than www) like lb.cm.
      else {
        $domain = $second_to_last . '.' . $last;
      }
    }
  }

  return $domain;
}