获取客户端的ip地址

function retrieveClientIp()
{
if(defined('IS_CLI') && IS_CLI==TRUE)
{
return '0.0.0.0';
}
if (getenv('HTTP_CLIENT_IP'))
{
$ip = getenv('HTTP_CLIENT_IP');
}
elseif (getenv('HTTP_X_FORWARDED_FOR'))
{ //获取客户端用代理服务器访问时的真实ip 地址
$ip = getenv('HTTP_X_FORWARDED_FOR');
}
elseif (getenv('HTTP_X_FORWARDED'))
{
$ip = getenv('HTTP_X_FORWARDED');
}
elseif (getenv('HTTP_FORWARDED_FOR'))
{
$ip = getenv('HTTP_FORWARDED_FOR');
}
elseif (getenv('HTTP_FORWARDED'))
{
$ip = getenv('HTTP_FORWARDED');
}
else
{
$ip = $_SERVER['REMOTE_ADDR'];
}
if(!$ip)
{
return '';
}
return  $ip
}