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 rustls

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. 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                                            2025-11-07                               CURLINFO_CERTINFO(3)