Tribblix: manual page: CURLOPT

CURLOPT_CRLFILE(3) Introduction to Library Functions CURLOPT_CRLFILE(3)

NAME

CURLOPT_CRLFILE - Certificate Revocation List file

SYNOPSIS

#include <curl/curl.h>

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

DESCRIPTION

Pass a char pointer to a null-terminated string naming a file with
the concatenation of CRL (in PEM format) to use in the certificate
validation that occurs during the SSL exchange.

When curl is built to use GnuTLS, there is no way to influence the
use of CRL passed to help in the verification process.

When libcurl is built with OpenSSL support, X509_V_FLAG_CRL_CHECK and
X509_V_FLAG_CRL_CHECK_ALL are both set, requiring CRL check against
all the elements of the certificate chain if a CRL file is passed.
Also note that CURLOPT_CRLFILE(3) implies CURLSSLOPT_NO_PARTIALCHAIN
(see CURLOPT_SSL_OPTIONS(3)) since curl 7.71.0 due to an OpenSSL bug.

This option makes sense only when used in combination with the
CURLOPT_SSL_VERIFYPEER(3) option.

A specific error code (CURLE_SSL_CRL_BADFILE) is defined with the
option. It is returned when the SSL exchange fails because the CRL
file cannot be loaded. A failure in certificate verification due to
a revocation information found in the CRL does not trigger this
specific error.

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

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

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,
OpenSSL, mbedTLS and rustls

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_CRLFILE, "/etc/certs/crl.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).