On Tue, 15 Sep 2009, Vincent Chen wrote:

> If I am using curl_easy_perform() to downloading large files, then client
> wants to cancel downloading, how sould I do to let socket close properly?

Cancel a download and close the socket are two indepdendent actions.

Cancel: http://curl.haxx.se/docs/faq.html#How_do_I_stop_an_ongoing_transfe

Close: http://curl.haxx.se/libcurl/c/curl_easy_cleanup.html

In general you don't need to worry about the closing, as long as you just use
the API as intended.

-- 
  / daniel.haxx.se