SSL_load_client_CA_file, SSL_add_file_cert_subjects_to_stack, SSL_add_dir_cert_subjects_to_stack - load certificate names

#include <openssl/ssl.h>
STACK_OF(X509_NAME) *SSL_load_client_CA_file(const char *file);
int SSL_add_file_cert_subjects_to_stack(STACK_OF(X509_NAME) *stack,
                                        const char *file)
int SSL_add_dir_cert_subjects_to_stack(STACK_OF(X509_NAME) *stack,
                                       const char *dir)

SSL_load_client_CA_file() reads certificates from file and returns a STACK_OF(X509_NAME) with the subject names found.

SSL_add_file_cert_subjects_to_stack() reads certificates from file, and adds their subject name to the already existing stack.

SSL_add_dir_cert_subjects_to_stack() reads certificates from every file in the directory dir, and adds their subject name to the already existing stack.

SSL_load_client_CA_file() reads a file of PEM formatted certificates and extracts the X509_NAMES of the certificates found. While the name suggests the specific usage as support function for SSL_CTX_set_client_CA_list(3), it is not limited to CA certificates.

The following return values can occur:

The operation failed, check out the error stack for the reason.
Pointer to the subject names of the successfully read certificates.

Load names of CAs from file and use it as a client CA list:

SSL_CTX *ctx;
STACK_OF(X509_NAME) *cert_names;
cert_names = SSL_load_client_CA_file("/path/to/CAfile.pem");
if (cert_names != NULL)
    SSL_CTX_set_client_CA_list(ctx, cert_names);
    /* error */

ssl(7), SSL_CTX_set_client_CA_list(3)

Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at

2022-07-05 1.1.1q