curl proxy digest auth

$curl=curl_init();
curl_setopt($curl,CURLOPT_URL,$url);
curl_setopt($curl,CURLOPT_HEADER,0);
curl_setopt($curl,CURLOPT_POST,1);
curl_setopt($curl,CURLOPT_RETURNTRANSFER,1);
curl_setopt($curl,CURLOPT_POSTFIELDS,$data);
curl_setopt($curl,CURLOPT_PROXY,$proxy_ip);
curl_setopt($curl,CURLOPT_PROXYPORT,$proxy_port);
curl_setopt($curl,CURLOPT_PROXYAUTH,CURLAUTH_DIGEST);
curl_setopt($curl,CURLOPT_PROXYUSERPWD,$proxy_user.':'.$proxy_password);
$result=curl_exec($curl);