I wrote a ftp client application which send NLST to server every 1s. Here is ftp server log:

(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> PASV
(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> 227 Entering Passive Mode (127,0,0,1,18,211)
(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> TYPE A
(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> 200 Type set to A
(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> NLST
(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> 150 Connection accepted
(000011) 2006-10-30 11:39:55 - zhou (127.0.0.1)> 226 Transfer OK

It seems that the PASV command is also sent and connection is re-established every time. What's wrong with it? My source code is like the following:

    CURL *curl = curl_easy_init();
    if ( curl )
    {
        while ( isRunning )
        {
            // send NLST
            list(curl);
            // download
                 download(curl);
            // sleep 1 second
            sleep(1000);
        }
     }
     curl_easy_cleanup(curl);

The libcurl document say it will try to keep the connection keep-alive / persistent when you use the same CURL. But why it'll reconnect every time when I send NLST command in my case?

Thanks
Received on 2006-10-30