获取公网ip地址

function getip(){
if(!empty($_SERVER["HTTP_CLIENT_IP"])){
$cip = $_SERVER["HTTP_CLIENT_IP"];
}
else if(!empty($_SERVER["HTTP_X_FORWARDED_FOR"])){
$cip = $_SERVER["HTTP_X_FORWARDED_FOR"];
}
else if(!empty($_SERVER["REMOTE_ADDR"])){
$cip = $_SERVER["REMOTE_ADDR"];
}
else{
$cip = '';
}
preg_match("/[\d\.]{7,15}/", $cip, $cips);
$cip = isset($cips[0]) ? $cips[0] : 'unknown';
unset($cips);
return $cip;
}