getIPAddress

<?php
    # this is an example of a bad idea
    # X_FORWARDED_FOR can be spoofed.

    public static function getIPAddress() {
      if ( isset($_SERVER['HTTP_X_FORWARDED_FOR']) ) {
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
      } elseif ( isset($_SERVER['HTTP_CLIENT_IP']) ) {
        $ip = $_SERVER['HTTP_CLIENT_IP'];
      } else {
        $ip = $_SERVER['REMOTE_ADDR'];
      }

      return $ip;
    }
?>