CURLOPT_CONNECTTIMEOUT_MS − timeout for the connect phase
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONNECTTIMEOUT_MS, long timeout);
Pass a long. It should contain the maximum time in milliseconds that you allow the connection phase to the server to take. This only limits the connection phase, it has no impact once it has connected. Set to zero to switch to the default built-in connection timeout - 300 seconds. See also the CURLOPT_TIMEOUT_MS(3) option.
In unix-like systems, this might cause signals to be used unless CURLOPT_NOSIGNAL(3) is set.
If both CURLOPT_CONNECTTIMEOUT(3) and CURLOPT_CONNECTTIMEOUT_MS(3) are set, the value set last will be used.
CURL *curl =
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
connection within 10000 milliseconds */
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT_MS, 10000L);
CURLOPT_CONNECTTIMEOUT(3), CURLOPT_TIMEOUT(3), CURLOPT_LOW_SPEED_LIMIT(3),