PHP 获取客户端IP

function get_ip()
{
static $realIP;
if (isset($_SERVER)){
if (isset($_SERVER["HTTP_X_FORWARDED_FOR"])){
$realIP = explode(',', $_SERVER["HTTP_X_FORWARDED_FOR"]);
$realIP = $realIP[0];
} else if (isset($_SERVER["HTTP_CLIENT_IP"])) {
$realIP = $_SERVER["HTTP_CLIENT_IP"];
} else {
$realIP = $_SERVER["REMOTE_ADDR"];
}
} else {
if (getenv("HTTP_X_FORWARDED_FOR")){
$realIP = getenv("HTTP_X_FORWARDED_FOR");
} else if (getenv("HTTP_CLIENT_IP")) {
$realIP = getenv("HTTP_CLIENT_IP");
} else {
$realIP = getenv("REMOTE_ADDR");
}
}
$_SERVER['REMOTE_ADDR'] = $realIP;
return $realIP;
}