CURLINFO_CERTINFO(3) - Man pages

CURLINFO_CERTINFO(3)        Library Functions Manual       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  certifi-
       cates  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, Secure Transport 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. 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).

SEE ALSO
       CURLINFO_CAPATH(3), curl_easy_getinfo(3), curl_easy_setopt(3)

libcurl                            2026-07-12              CURLINFO_CERTINFO(3)

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