Tribblix: manual page: CURLINFO

CURLINFO_CERTINFO(3) Introduction to Library Functions CURLINFO_CERTINFO(3)

NAME

CURLINFO_CERTINFO - TLS certificate chain

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_CERTINFO,
struct curl_certinfo **chainp);

DESCRIPTION

Pass a pointer to a struct curl_certinfo * and it is set to point to
a struct that holds info about the server's certificate chain,
assuming you had CURLOPT_CERTINFO(3) enabled when the request was
made.

struct curl_certinfo {
int num_of_certs;
struct curl_slist **certinfo;
};

The certinfo struct member is an array of linked lists of certificate
information. The num_of_certs struct member is the number of
certificates which is the number of elements in the array. Each
certificate's list has items with textual information in the format
"name:content" such as "Subject:Foo", "Issuer:Bar", etc. The items in
each list varies depending on the SSL backend and the certificate.

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

if(!result) {
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);
}
}

See also the certinfo.c example.

HISTORY

GnuTLS support added in 7.42.0. 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_getinfo(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).