SSL_LOAD_CLIENT_CA_FILE(3) OpenSSL SSL_LOAD_CLIENT_CA_FILE(3)

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:
NULL
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);
 else
     /* error */
 ...

ssl(7), SSL_CTX_set_client_CA_list(3)

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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 <https://www.openssl.org/source/license.html>.

2022-07-05 1.1.1q