求帮忙修改个php curl模拟post请求内容后并下载文件的解决思路

下面代码使用curl模拟post请求链接后直接显示出了文件内容，如何修改成不显示内容而直接下载请求到的.torrent格式文件呢

								function curl_post($header,$data,$url)

								{

								 $ch = curl_init();

								 $res= curl_setopt ($ch, CURLOPT_URL,$url);

								 curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);

								 curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);

								 curl_setopt ($ch, CURLOPT_HEADER, 0);

								 curl_setopt($ch, CURLOPT_POST, 1);

								 curl_setopt($ch, CURLOPT_POSTFIELDS, $data);

								 curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);

								 curl_setopt($ch,CURLOPT_HTTPHEADER,$header);

								 $result = curl_exec ($ch);

								 curl_close($ch);

								 if ($result == NULL) {

								 return 0;

								 }

								 return $result;

								} 

								 $url = 'http://www.bttiantang.com/download4.php' ; 

								 $header = array("Host:www.bttiantang.com",

								 "Content-Type:application/x-www-form-urlencoded",

								 'User-Agent: Mozilla/4.0 (compatible; MSIE .0; Windows NT 6.1; Trident/4.0; SLCC2;)'); 

								$data = 'action=download&id=26881&uhash=eecf3d3071a7b672c314bc39';

								$ret = curl_post($header, $data,$url);

								//需将内容显示修改为文件下载

								echo $ret;

------解决思路----------------------

不要echo $ret;

把$ret写入文件中去。保存起来

------解决思路----------------------

									$ret = curl_post($header, $data,$url);

									//需将内容显示修改为文件下载

									$filename = 'x.torrent';

									header("Content-Type: application/force-download");

									header("Content-Disposition: attachment; filename=$filename"); 

									echo $ret;