SessionConfiguration::getCookieDomain

protected SessionConfiguration::getCookieDomain(Request $request)

protected function getCookieDomain(Request $request) {
  if (isset($this->options['cookie_domain'])) {
    $cookie_domain = $this->options['cookie_domain'];
  }
  else {
    $host = $request->getHost();
    // To maximize compatibility and normalize the behavior across user
    // agents, the cookie domain should start with a dot.
    $cookie_domain = '.' . $host;
  }

  // Cookies for domains without an embedded dot will be rejected by user
  // agents in order to defeat malicious websites attempting to set cookies
  // for top-level domains. Also IP addresses may not be used in the domain
  // attribute of a Set-Cookie header.
  if (count(explode('.', $cookie_domain)) > 2 && !is_numeric(str_replace('.', '', $cookie_domain))) {
    return $cookie_domain;
  }
}