Tribblix: manual page: CURLINFO

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

NAME

CURLINFO_CERTINFO - get the 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, Schannel and Secure Transport

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
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);

res = curl_easy_perform(curl);

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

if(!res) {
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.
Secure Transport support added in 7.79.0. 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).