int AsyncSSLSocket::getSSLExDataIndex() {
  static auto index = SSL_get_ex_new_index(
      0, (void*)"AsyncSSLSocket data index", nullptr, nullptr, nullptr);
  return index;
}
int AsyncSSLSocket::getSSLExDataIndex() {
  static auto index = SSL_get_ex_new_index(
      0, (void*)"AsyncSSLSocket data index", nullptr, nullptr, nullptr);
  return index;
}