CURLOPT_CERTINFO3

Usage

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

Overview

Pass a long set to 1 to enable libcurl's certificate chain info gatherer. With this enabled, libcurl extracts lots of information and data about the certificates in the certificate chain used in the SSL connection. This data may then be retrieved after a transfer using curl_easy_getinfo(3) and its option CURLINFO_CERTINFO(3).

Default

0

Protocols

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

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

Examples

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://www.example.com/");
    /* connect to any HTTPS site, trusted or not */
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
    curl_easy_setopt(curl, CURLOPT_CERTINFO, 1L);
    result = curl_easy_perform(curl);
    if(result == CURLE_OK) {
      struct curl_certinfo *ci;
      result = curl_easy_getinfo(curl, CURLINFO_CERTINFO, &ci);
      if(result == CURLE_OK) {
        int i;
        printf("%d certs!\n", ci->num_of_certs);
        for(i = 0; i < ci->num_of_certs; i++) {
          struct curl_slist *slist;
          for(slist = ci->certinfo[i]; slist; slist = slist->next)
            printf("%s\n", slist->data);
        }
      }
    }
    curl_easy_cleanup(curl);
  }
}

Return value

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).