ip.get.php

<?php
/**
 * User IP
 *
 * @category   validate
 * @version   0.1
 * @license 	GNU General Public License (GPL), http://www.gnu.org/copyleft/gpl.html
 * @param string $out IP адрес который будет отдан функцией, если больше ничего не обнаружено
 * @return string IP пользователя
 * @author Agel_Nash <Agel_Nash@xaker.ru>
 * 
 * @see http://stackoverflow.com/questions/5036443/php-how-to-block-proxies-from-my-site
 */
function getUserIP($out='127.0.0.1'){
  //see: http://www.php.net/manual/ru/functions.anonymous.php
	$getEnv = function($data){
		$out=false;
		switch(true){
			case (isset($_SERVER[$data])): 
				$out = $_SERVER[$data]; break;
			case (isset($_ENV[$data])): 
				$out = $_ENV[$data]; break;
			case ($tmp = getenv($data)): 
				$out = $tmp; break;
			case (function_exists('apache_getenv') && $tmp=apache_getenv($data, true)):
				$out = $tmp; break;
			default: 
				$out = false;
		}
		unset($tmp);
		return $out;
	};

	//Порядок условий зависит от приоритетов
	switch(true){
		case ($tmp = $getEnv('HTTP_COMING_FROM')): 
			$out = $tmp; break;
		case ($tmp = $getEnv('HTTP_X_COMING_FROM')):
			$out = $tmp; break;
		case ($tmp = $getEnv('HTTP_VIA')): 
			$out = $tmp; break;
		case ($tmp = $getEnv('HTTP_FORWARDED')): 
			$out = $tmp; break;
		case ($tmp = $getEnv('HTTP_FORWARDED_FOR')):
			$out = $tmp; break;
		case ($tmp = $getEnv('HTTP_X_FORWARDED')): 
			$out = $tmp; break;
		case ($tmp = $getEnv('HTTP_X_FORWARDED_FOR')):
			$out = $tmp; break;
		case (!empty($_SERVER['REMOTE_ADDR'])): 
			$out=$_SERVER['REMOTE_ADDR']; break;
		default: 
			$out = false;
	}
	unset($tmp);
	
	return (false!==$out && preg_match('|^(?:[0-9]{1,3}\.){3,3}[0-9]{1,3}$|',$out, $matches)) ? $out : false;
}