CURLOPT_CONNECTTIMEOUT explained

Name

CURLOPT_CONNECTTIMEOUT - timeout for the connect phase

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONNECTTIMEOUT, long timeout);

Description

Pass a long. It sets the maximum time in seconds that you allow the connection phase to take. This timeout only limits the connection phase, it has no impact once libcurl has connected. The connection phase includes the name resolve (DNS) and all protocol handshakes and negotiations until there is an established connection with the remote side.

Set this option to zero to switch to the default built-in connection timeout - 300 seconds. See also the CURLOPT_TIMEOUT option.

CURLOPT_CONNECTTIMEOUT_MS is the same function but set in milliseconds.

If both CURLOPT_CONNECTTIMEOUT and CURLOPT_CONNECTTIMEOUT_MS are set, the value set last is used.

The connection timeout is included in the general all-covering CURLOPT_TIMEOUT:

With CURLOPT_CONNECTTIMEOUT set to 3 and CURLOPT_TIMEOUT set to 5, the operation can never last longer than 5 seconds, and the connection phase cannot last longer than 3 seconds.

With CURLOPT_CONNECTTIMEOUT set to 4 and CURLOPT_TIMEOUT set to 2, the operation can never last longer than 2 seconds. Including the connection phase.

This option may cause libcurl to use the SIGALRM signal to timeout system calls on builds not using asynch DNS. In Unix-like systems, this might cause signals to be used unless CURLOPT_NOSIGNAL is set.

Default

300

Protocols

This functionality affects all supported protocols

Example

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 
    /* complete connection within 10 seconds */
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 10L);
 
    curl_easy_perform(curl);
  }
}

Availability

Added in curl 7.7

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors.