curl / libcurl / API / curl_easy_setopt / CURLOPT_TCP_KEEPALIVE

CURLOPT_TCP_KEEPALIVE explained

Name

CURLOPT_TCP_KEEPALIVE - TCP keep-alive probing

Synopsis

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

Description

Pass a long. If set to 1, TCP keepalive probes are used. The delay and frequency of these probes can be controlled by the CURLOPT_TCP_KEEPIDLE, CURLOPT_TCP_KEEPINTVL, and CURLOPT_TCP_KEEPCNT options, provided the operating system supports them. Set to 0 (default behavior) to disable keepalive probes.

Default

Protocols

This functionality affects tcp only

Example

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
 
    /* enable TCP keep-alive for this transfer */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPALIVE, 1L);
 
    /* keep-alive idle time to 120 seconds */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPIDLE, 120L);
 
    /* interval time between keep-alive probes: 60 seconds */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPINTVL, 60L);
 
    /* maximum number of keep-alive probes: 3 */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPCNT, 3L);
 
    curl_easy_perform(curl);
  }
}

Availability

Added in curl 7.25.0

Return value

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.