Whitelist Sites with CF Header

whitelist.php

$whitelistCountries = array(
  "NZ"
  );

if(isset($_SERVER["HTTP_CF_IPCOUNTRY"])) {
  $block = true;
  for($whitelistCountries as $country) {
    if($_SERVER["HTTP_CF_IPCOUNTRY"] == $country) {
      $block = false;
    }
  }
  if($block) {
    die('Country Disallowed');
  }
}