NAME

       SSL_CTX_set_client_CA_list, SSL_set_client_CA_list, SSL_CTX_add_client_CA,
       SSL_add_client_CA - set list of CAs sent to the client when requesting a client
       certificate

SYNOPSIS

        #include <openssl/ssl.h>

        void SSL_CTX_set_client_CA_list(SSL_CTX *ctx, STACK_OF(X509_NAME) *list);
        void SSL_set_client_CA_list(SSL *s, STACK_OF(X509_NAME) *list);
        int SSL_CTX_add_client_CA(SSL_CTX *ctx, X509 *cacert);
        int SSL_add_client_CA(SSL *ssl, X509 *cacert);

DESCRIPTION

       SSL_CTX_set_client_CA_list() sets the list of CAs sent to the client when requesting a
       client certificate for ctx.

       SSL_set_client_CA_list() sets the list of CAs sent to the client when requesting a client
       certificate for the chosen ssl, overriding the setting valid for ssl's SSL_CTX object.

       SSL_CTX_add_client_CA() adds the CA name extracted from cacert to the list of CAs sent to
       the client when requesting a client certificate for ctx.

       SSL_add_client_CA() adds the CA name extracted from cacert to the list of CAs sent to the
       client when requesting a client certificate for the chosen ssl, overriding the setting
       valid for ssl's SSL_CTX object.

NOTES

       When a TLS/SSL server requests a client certificate (see SSL_CTX_set_verify(3)), it sends
       a list of CAs, for which it will accept certificates, to the client.

       This list must explicitly be set using SSL_CTX_set_client_CA_list() for ctx and
       SSL_set_client_CA_list() for the specific ssl. The list specified overrides the previous
       setting. The CAs listed do not become trusted (list only contains the names, not the
       complete certificates); use SSL_CTX_load_verify_locations(3) to additionally load them for
       verification.

       If the list of acceptable CAs is compiled in a file, the SSL_load_client_CA_file(3)
       function can be used to help importing the necessary data.

       SSL_CTX_add_client_CA() and SSL_add_client_CA() can be used to add additional items the
       list of client CAs. If no list was specified before using SSL_CTX_set_client_CA_list() or
       SSL_set_client_CA_list(), a new client CA list for ctx or ssl (as appropriate) is opened.

       These functions are only useful for TLS/SSL servers.

RETURN VALUES

       SSL_CTX_set_client_CA_list() and SSL_set_client_CA_list() do not return diagnostic
       information.

       SSL_CTX_add_client_CA() and SSL_add_client_CA() have the following return values:

       0   A failure while manipulating the STACK_OF(X509_NAME) object occurred or the X509_NAME
           could not be extracted from cacert. Check the error stack to find out the reason.

       1   The operation succeeded.

EXAMPLES

       Scan all certificates in CAfile and list them as acceptable CAs:

        SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(CAfile));

SEE ALSO

       ssl(7), SSL_get_client_CA_list(3), SSL_load_client_CA_file(3),
       SSL_CTX_load_verify_locations(3)

COPYRIGHT

       Copyright 2000-2016 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 <https://www.openssl.org/source/license.html>.