CURLOPT_CA_CACHE_TIMEOUT - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CA_CACHE_TIMEOUT, long age);

Pass a long, this sets the timeout in seconds. This tells libcurl the maximum time any cached CA certificate store it has in memory may be kept and reused for new connections. Once the timeout has expired, a subsequent fetch requiring a CA certificate has to reload it.

Building a CA certificate store from a CURLOPT_CAINFO(3) file is a slow operation so curl may cache the generated certificate store internally to speed up future connections.

Set the timeout to zero to completely disable caching, or set to -1 to retain the cached store remain forever. By default, libcurl caches this info for 24 hours.

86400 (24 hours)

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

This option works only with the following TLS backends: GnuTLS, OpenSSL, Schannel and wolfSSL

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");

    /* only reuse certificate stores for a short time */
    curl_easy_setopt(curl, CURLOPT_CA_CACHE_TIMEOUT, 60L);

    res = curl_easy_perform(curl);

    /* in this second request, the cache is not used if more than
       sixty seconds passed since the previous connection */
    res = curl_easy_perform(curl);

    curl_easy_cleanup(curl);
  }
}

This option is supported by OpenSSL and its forks (since 7.87.0), Schannel (since 8.5.0), wolfSSL (since 8.9.0) and GnuTLS (since 8.9.0).

Added in curl 7.87.0

Returns CURLE_OK

CURLOPT_CAINFO(3), CURLOPT_CAINFO_BLOB(3), CURLOPT_CAPATH(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_SSL_VERIFYPEER(3)

curl_easy_setopt(3), CURLOPT_CAINFO(3), CURLOPT_SSL_CTX_FUNCTION(3), libcurl-symbols(3).