获取访问者IP（PHP代码函数）

//获取访问者IP（PHP代码函数）
//代码来源：Monxin ./config/functions.php
function get_ip(){
if(getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"),"unknown")){
$ip=getenv("HTTP_CLIENT_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;
}