Tribblix: manual page: CURLOPT

CURLOPT_ISSUERCERT(3) Introduction to Library Functions

NAME

CURLOPT_ISSUERCERT - issuer SSL certificate filename

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ISSUERCERT, char *file);

DESCRIPTION

Pass a char pointer to a null-terminated string naming a file holding
a CA certificate in PEM format. If the option is set, an additional
check against the peer certificate is performed to verify the issuer
is indeed the one associated with the certificate provided by the
option. This additional check is useful in multi-level PKI where one
needs to enforce that the peer certificate is from a specific branch
of the tree.

This option makes sense only when used in combination with the
CURLOPT_SSL_VERIFYPEER(3) option. Otherwise, the result of the check
is not considered as failure.

A specific error code (CURLE_SSL_ISSUER_ERROR) is defined with the
option, which is returned if the setup of the SSL/TLS session has
failed due to a mismatch with the issuer of peer certificate
(CURLOPT_SSL_VERIFYPEER(3) has to be set too for the check to fail).
(Added in 7.19.0)

Using this option multiple times makes the last set string override
the previous ones. Set it to NULL to disable its use again.

The application does not have to keep the string around after setting
this option.

DEFAULT

NULL

PROTOCOLS

This functionality affects all TLS based protocols: HTTPS, FTPS,
IMAPS, POP3S, SMTPS etc.

This option works only with the following TLS backends: GnuTLS and
OpenSSL

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
curl_easy_setopt(curl, CURLOPT_ISSUERCERT, "/etc/certs/cacert.pem");
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY

Added in curl 7.19.0

RETURN VALUE

curl_easy_setopt(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).