CURLINFO_CERTINFO(3) Library Functions Manual 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 == CURLE_OK) {
int i;
struct curl_certinfo *ci;
result = curl_easy_getinfo(curl, CURLINFO_CERTINFO, &ci);
if(result == CURLE_OK) {
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).
SEE ALSO
CURLINFO_CAPATH(3), curl_easy_getinfo(3), curl_easy_setopt(3)
libcurl 2026-03-23 CURLINFO_CERTINFO(3)
curl 8.19.0 - Generated Tue Mar 24 16:16:21 CDT 2026