PHP Download Remote large file (get remote file size)

<?PHP//temporarily does not support the continuation of the breakpoint//$url = ' http://www.mytest.com/debian.iso '; do not know why get local file size is 0    $url= ' HTTP://192.168.8.93/DOWNLOAD/VM-672/18/0.VMDK '; $file=basename($url); $header=get_headers($url, 1); $size=$header[' Content-length ']; $fp=fopen($url, ' RB '); if($fp===false)Exit(' file does not exist or failed to open '); Header(' Content-description:file Transfer '); Header(' Content-type:application/octet-stream '); Header(' Content-disposition:attachment; Filename= '.$file.'"'); Header(' Content-transfer-encoding:binary '); Header(' expires:0 '); Header(' Cache-control:must-revalidate, post-check=0, pre-check=0 '); Header(' Pragma:public '); Header(' Content-length: '.$size); Ob_clean(); Ob_end_flush(); Set_time_limit(0); $chunkSize= 1024 * 1024;  while(!feof($fp)) {        $buffer=fread($fp,$chunkSize); Echo $buffer; Ob_flush(); Flush(); }    fclose($fp); Exit;