curl/docs/libcurl/opts/CURLINFO_CERTINFO.md

---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLINFO_CERTINFO
Section: 3
Source: libcurl
See-also:
  - CURLINFO_CAPATH (3)
  - curl_easy_getinfo (3)
  - curl_easy_setopt (3)
Protocol:
  - TLS
TLS-backend:
  - OpenSSL
  - GnuTLS
  - Schannel
  - Secure Transport
---

# NAME

CURLINFO_CERTINFO - get the TLS certificate chain

# SYNOPSIS

~~~c
#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.

~~~c
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.

# EXAMPLE

~~~c
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.

# AVAILABILITY

This option is only working in libcurl built with OpenSSL, GnuTLS, Schannel,
Secure Transport or mbedTLS. 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.

Added in 7.19.1

# RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.