Tribblix: manual page: CURLOPT

CURLOPT_CERTINFO(3) Introduction to Library Functions CURLOPT_CERTINFO(3)

NAME

CURLOPT_CERTINFO - request SSL certificate information

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CERTINFO, long certinfo);

DESCRIPTION

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

PROTOCOLS

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

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

EXAMPLE

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) {
struct curl_certinfo *ci;
result = curl_easy_getinfo(curl, CURLINFO_CERTINFO, &ci);

if(!result) {
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);
}
}

HISTORY

Schannel support added in 7.50.0. mbedTLS support added in 8.9.0.

AVAILABILITY

Added in curl 7.19.1

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).