=pod

=head1 NAME

SSL_load_client_CA_file,
SSL_add_file_cert_subjects_to_stack,
SSL_add_dir_cert_subjects_to_stack
- load certificate names

=head1 SYNOPSIS

 #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)

=head1 DESCRIPTION

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

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

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

=head1 NOTES

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
L<SSL_CTX_set_client_CA_list(3)>,
it is not limited to CA certificates.

=head1 RETURN VALUES

The following return values can occur:

=over 4

=item NULL

The operation failed, check out the error stack for the reason.

=item Pointer to STACK_OF(X509_NAME)

Pointer to the subject names of the successfully read certificates.

=back

=head1 EXAMPLES

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 */
 ...

=head1 SEE ALSO

L<ssl(7)>,
L<SSL_CTX_set_client_CA_list(3)>

=head1 COPYRIGHT

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

=cut