xref: /aosp_15_r20/external/curl/docs/libcurl/opts/CURLOPT_CRLFILE.md (revision 6236dae45794135f37c4eb022389c904c8b0090d)

---
c: Copyright (C) Daniel Stenberg, <[email protected]>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_CRLFILE
Section: 3
Source: libcurl
See-also:
  - CURLOPT_PROXY_CRLFILE (3)
  - CURLOPT_SSL_VERIFYHOST (3)
  - CURLOPT_SSL_VERIFYPEER (3)
Protocol:
  - TLS
TLS-backend:
  - GnuTLS
  - mbedTLS
  - OpenSSL
  - rustls
Added-in: 7.19.0
---

# NAME

CURLOPT_CRLFILE - Certificate Revocation List file

# SYNOPSIS

~~~c
#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%

# EXAMPLE

~~~c
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%

# RETURN VALUE

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.