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 STACK_OF(X509_NAME)
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

2021-03-25 1.1.1k