PHP 获取客户端ip

function get_client_ip() {
     if (getenv("HTTP_CLINET_IP") && strcasecmp(getnenv("HTTP_CLINET_IP")), "unknown") {
          $ip = getenv("HTTP_CLINET_IP");
     } else if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown")) {
          $ip = getenv("HTTP_X_FORWARDED_FOR");
     } else if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown")){
          $ip = getenv("REMOTE_ADDR");
     } else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER["REMOTE_ADDR"] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown")) {
          $ip = $_SERVER["REMOTE_ADDR"];
     } else {
          $ip = "unknown";
     }
     return $ip;
}