/**
* 获取客户端IP地址
* @return ip地址
*/
function get_ip() {
static $ip = NULL;
if ($ip !== NULL) return $ip;
if (isset($_SERVER[HTTP_X_FORWARDED_FOR])) {
$arr = explode(,, $_SERVER[HTTP_X_FORWARDED_FOR]);
$pos = array_search(unknown,$arr);
if(false !== $pos) unset($arr[$pos]);
$ip = trim($arr[0]);
}elseif (isset($_SERVER[HTTP_CLIENT_IP])) {
$ip = $_SERVER[HTTP_CLIENT_IP];
}elseif (isset($_SERVER[REMOTE_ADDR])) {
$ip = $_SERVER[REMOTE_ADDR];
}
return $ip;
}