PHP cURL通过浏览器下载文件

Im create script to download file from some file server but not work perfectly.

        function downloadPage2($url){

        $ch = curl_init();
        $userAgent = 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322)';
        curl_setopt($ch, CURLOPT_USERAGENT, $userAgent);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_VERBOSE, 1);
        curl_setopt($ch, CURLOPT_AUTOREFERER, false);   
        curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie.txt');
        curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookie.txt');
        curl_setopt($ch, CURLOPT_HEADER, 1);
        curl_setopt($ch, CURLOPT_BUFFERSIZE, 8096);
        curl_setopt($ch, CURLOPT_BINARYTRANSFER, true);
        curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $buffer) {

            header('Expires: 0'); // no cache
            header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
            header('Last-Modified: ' . gmdate('D, d M Y H:i:s', time()) . ' GMT');
            header('Cache-Control: private', false);
            header('Content-Type: application/force-download');
            header('Content-Disposition: attachment; filename="mp3.mp3"');
            header('Content-Transfer-Encoding: binary');
//          header('Content-Length: ' . strlen($buffer)); // provide file size
            header('Connection: close');
            echo $buffer;
              return strlen($buffer);
            });
        curl_exec ($ch);
        curl_close($ch);
    }

And when type $url to file (mp3) from server its download this file but not right filesize. Example: File on server has size 4.5mb and my script downloaded it but size is 6mb. Music is playing but interrupts per second. Do you know where is a problem?

I tried set content-lenght in header but every function return content lengh = 0

Try this, it worked for me download large files

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $source);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
// if https
curl_setopt($ch, CURLOPT_SSLVERSION, 3);
// or set this option
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
$data = curl_exec($ch);

$error = curl_error($ch);
$file = $data = curl_exec($ch);
curl_close($ch);
if (file_exists($file)) {
  header("Content-Type: audio/mpeg, audio/x-mpeg, audio/x-mpeg-3, audio/mpeg3");
  header('Content-Disposition: attachment; filename="sometrack.mp3"');
  header("Content-Transfer-Encoding: binary");
  header('Content-length: ' . filesize($file));
  header('X-Pad: avoid browser bug');
  header('Cache-Control: no-cache');
  readfile($file);
} else {
  echo "no file";
}

This code is working fine with me, I am using php readfile function to read the file from a remote host as per documentation for readfile:

A URL can be used as a filename with this function if the fopen_wrappers have been enabled. See fopen() for more details on how to specify the filename. See the Supported Protocols and Wrappers for links to information about what abilities the various wrappers have, notes on their usage, and information on any predefined variables they may provide.

        header('Content-Type:'.$this->get_mime_type($url));
        header("Content-Transfer-Encoding: Binary");
        header("Content-disposition: attachment; filename=".$filename);
        echo readfile($url);


 function get_mime_type($filename) {
    $idx = explode( '.', $filename );
    $count_explode = count($idx);
    $idx = strtolower($idx[$count_explode-1]);

    $mimet = array(
        'txt' => 'text/plain',
        'htm' => 'text/html',
        'html' => 'text/html',
        'php' => 'text/html',
        'css' => 'text/css',
        'js' => 'application/javascript',
        'json' => 'application/json',
        'xml' => 'application/xml',
        'swf' => 'application/x-shockwave-flash',
        'flv' => 'video/x-flv',

        // images
        'png' => 'image/png',
        'jpe' => 'image/jpeg',
        'jpeg' => 'image/jpeg',
        'jpg' => 'image/jpeg',
        'gif' => 'image/gif',
        'bmp' => 'image/bmp',
        'ico' => 'image/vnd.microsoft.icon',
        'tiff' => 'image/tiff',
        'tif' => 'image/tiff',
        'svg' => 'image/svg+xml',
        'svgz' => 'image/svg+xml',

        // archives
        'zip' => 'application/zip',
        'rar' => 'application/x-rar-compressed',
        'exe' => 'application/x-msdownload',
        'msi' => 'application/x-msdownload',
        'cab' => 'application/vnd.ms-cab-compressed',

        // audio/video
        'mp3' => 'audio/mpeg',
        'qt' => 'video/quicktime',
        'mov' => 'video/quicktime',

        // adobe
        'pdf' => 'application/pdf',
        'psd' => 'image/vnd.adobe.photoshop',
        'ai' => 'application/postscript',
        'eps' => 'application/postscript',
        'ps' => 'application/postscript',

        // ms office
        'doc' => 'application/msword',
        'rtf' => 'application/rtf',
        'xls' => 'application/vnd.ms-excel',
        'ppt' => 'application/vnd.ms-powerpoint',
        'docx' => 'application/msword',
        'xlsx' => 'application/vnd.ms-excel',
        'pptx' => 'application/vnd.ms-powerpoint',


        // open office
        'odt' => 'application/vnd.oasis.opendocument.text',
        'ods' => 'application/vnd.oasis.opendocument.spreadsheet',
    );

    if (isset( $mimet[$idx] )) {
        return $mimet[$idx];
    } else {
        return 'application/octet-stream';
    }
}