Merge the CA list documentation for clarity

=head1 NAME

SSL_set0_CA_list, SSL_CTX_set0_CA_list, SSL_get0_CA_list,

SSL_CTX_get0_CA_list, SSL_add1_to_CA_list, SSL_CTX_add1_to_CA_list,

SSL_get0_peer_CA_list - get or set CA list

SSL_CTX_set_client_CA_list,

SSL_set_client_CA_list,

SSL_get_client_CA_list,

SSL_CTX_get_client_CA_list,

SSL_CTX_add_client_CA,

SSL_add_client_CA,

SSL_set0_CA_list,

SSL_CTX_set0_CA_list,

SSL_get0_CA_list,

SSL_CTX_get0_CA_list,

SSL_add1_to_CA_list,

SSL_CTX_add1_to_CA_list,

SSL_get0_peer_CA_list

- get or set CA list

=head1 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);

 STACK_OF(X509_NAME) *SSL_get_client_CA_list(const SSL *s);

 STACK_OF(X509_NAME) *SSL_CTX_get_client_CA_list(const SSL_CTX *ctx);

 int SSL_CTX_add_client_CA(SSL_CTX *ctx, X509 *cacert);

 int SSL_add_client_CA(SSL *ssl, X509 *cacert);

 void SSL_CTX_set0_CA_list(SSL_CTX *ctx, STACK_OF(X509_NAME) *name_list);

 void SSL_set0_CA_list(SSL *s, STACK_OF(X509_NAME) *name_list);

 const STACK_OF(X509_NAME) *SSL_CTX_get0_CA_list(const SSL_CTX *ctx);

=head1 DESCRIPTION

The functions described here set and manage the list of CA names that are sent

between two communicating peers.

For TLS versions 1.2 and earlier the list of CA names is only sent from the

server to the client when requesting a client certificate. So any list of CA

names set is never sent from client to server and the list of CA names retrieved

by SSL_get0_peer_CA_list() is always B<NULL>.

For TLS 1.3 the list of CA names is sent using the B<certificate_authorities>

extension and may be sent by a client (in the ClientHello message) or by

a server (when requesting a certificate).

In most cases it is not necessary to set CA names on the client side. The list

of CA names that are acceptable to the client will be sent in plaintext to the

server. This has privacy implications and may also have performance implications

if the list is large. This optional capability was introduced as part of TLSv1.3

and therefore setting CA names on the client side will have no impact if that

protocol version has been disabled. Most servers do not need this and so this

should be avoided unless required.

The "client CA list" functions below only have an effect when called on the

server side.

SSL_CTX_set_client_CA_list() sets the B<list> of CAs sent to the client when

requesting a client certificate for B<ctx>. Ownership of B<list> is transferred

to B<ctx> and it should not be freed by the caller.

SSL_set_client_CA_list() sets the B<list> of CAs sent to the client when

requesting a client certificate for the chosen B<ssl>, overriding the

setting valid for B<ssl>'s SSL_CTX object. Ownership of B<list> is transferred

to B<s> and it should not be freed by the caller.

SSL_CTX_get_client_CA_list() returns the list of client CAs explicitly set for

B<ctx> using SSL_CTX_set_client_CA_list(). The returned list should not be freed

by the caller.

SSL_get_client_CA_list() returns the list of client CAs explicitly

set for B<ssl> using SSL_set_client_CA_list() or B<ssl>'s SSL_CTX object with

SSL_CTX_set_client_CA_list(), when in server mode. In client mode,

SSL_get_client_CA_list returns the list of client CAs sent from the server, if

any. The returned list should not be freed by the caller.

SSL_CTX_add_client_CA() adds the CA name extracted from B<cacert> to the

list of CAs sent to the client when requesting a client certificate for

B<ctx>.

SSL_add_client_CA() adds the CA name extracted from B<cacert> to the

list of CAs sent to the client when requesting a client certificate for

the chosen B<ssl>, overriding the setting valid for B<ssl>'s SSL_CTX object.

SSL_get0_peer_CA_list() retrieves the list of CA names (if any) the peer

has sent. This can be called on either the server or the client side. The

returned list should not be freed by the caller.

The "generic CA list" functions below are very similar to the "client CA

list" functions except that they have an effect on both the server and client

sides. The lists of CA names managed are separate - so you cannot (for example)

set CA names using the "client CA list" functions and then get them using the

"generic CA list" functions. Where a mix of the two types of functions has been

used on the server side then the "client CA list" functions take precedence.

Typically, on the server side, the "client CA list " functions should be used in

preference. As noted above in most cases it is not necessary to set CA names on

the client side. 

SSL_CTX_set0_CA_list() sets the list of CAs to be sent to the peer to

B<name_list>. Ownership of B<name_list> is transferred to B<ctx> and

it should not be freed by the caller.

B<name_list> is transferred to B<s> and it should not be freed by the caller.

SSL_CTX_get0_CA_list() retrieves any previously set list of CAs set for

B<ctx>.

B<ctx>. The returned list should not be freed by the caller.

SSL_CTX_get0_CA_list() retrieves any previously set list of CAs set for

B<s> or if none are set the list from the parent B<SSL_CTX> is retrieved.

SSL_get0_CA_list() retrieves any previously set list of CAs set for

B<s> or if none are set the list from the parent B<SSL_CTX> is retrieved. The

returned list should not be freed by the caller.

SSL_CTX_add1_to_CA_list() appends the CA subject name extracted from B<x> to the

list of CAs sent to peer for B<ctx>.

list of CAs sent to the peer for B<s>, overriding the setting in the parent

B<SSL_CTX>.

SSL_get0_peer_CA_list() retrieves the list of CA names (if any) the peer

has sent.

=head1 NOTES

These functions are generalised versions of the client authentication

CA list functions such as L<SSL_CTX_set_client_CA_list(3)>. If both these

and L<SSL_CTX_set_client_CA_list(3)> or similar functions are used, then the

latter functions take priority on the server side (they are ignored on the

client side).

When a TLS/SSL server requests a client certificate (see

B<SSL_CTX_set_verify(3)>), it sends a list of CAs, for which it will accept

certificates, to the client.

For TLS versions before 1.3 the list of CA names is only sent from the server

to client when requesting a client certificate. So any list of CA names set

is never sent from client to server and the list of CA names retrieved by

SSL_get0_peer_CA_list() is always B<NULL>.

This list must explicitly be set using SSL_CTX_set_client_CA_list() or

SSL_CTX_set0_CA_list() for B<ctx> and SSL_set_client_CA_list() or

SSL_set0_CA_list() for the specific B<ssl>. The list specified

overrides the previous setting. The CAs listed do not become trusted (B<list>

only contains the names, not the complete certificates); use

L<SSL_CTX_load_verify_locations(3)> to additionally load them for verification.

For TLS 1.3 the list of CA names is sent using the B<certificate_authorities>

extension and will be sent by a client (in the ClientHello message) or by

a server (when requesting a certificate).

If the list of acceptable CAs is compiled in a file, the

L<SSL_load_client_CA_file(3)> function can be used to help to import the

necessary data.

SSL_CTX_add_client_CA(), SSL_CTX_add1_to_CA_list(), SSL_add_client_CA() and

SSL_add1_to_CA_list() can be used to add additional items the list of CAs. If no

list was specified before using SSL_CTX_set_client_CA_list(),

SSL_CTX_set0_CA_list(), SSL_set_client_CA_list() or SSL_set0_CA_list(), a

new CA list for B<ctx> or B<ssl> (as appropriate) is opened.

=head1 RETURN VALUES

SSL_CTX_set0_CA_list() and SSL_set0_CA_list() do not return a value.

SSL_CTX_set_client_CA_list(), SSL_set_client_CA_list(),

SSL_CTX_set_client_CA_list(), SSL_set_client_CA_list(), SSL_CTX_set0_CA_list()

and SSL_set0_CA_list() do not return a value.

SSL_CTX_get0_CA_list() and SSL_get0_CA_list() return a stack of CA names

or B<NULL> is no CA names are set.

SSL_CTX_get_client_CA_list(), SSL_get_client_CA_list(), SSL_CTX_get0_CA_list()

and SSL_get0_CA_list() return a stack of CA names or B<NULL> is no CA names are

set.

SSL_CTX_add1_to_CA_list() and SSL_add1_to_CA_list() return 1 for success and 0

for failure.

SSL_CTX_add_client_CA(),SSL_add_client_CA(), SSL_CTX_add1_to_CA_list() and

SSL_add1_to_CA_list() return 1 for success and 0 for failure.

SSL_get0_peer_CA_list() returns a stack of CA names sent by the peer or

B<NULL> or an empty stack if no list was sent.

=head1 EXAMPLES

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

 SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(CAfile));

=head1 SEE ALSO

L<ssl(7)>,

L<SSL_CTX_set_client_CA_list(3)>,

L<SSL_get_client_CA_list(3)>,

L<SSL_load_client_CA_file(3)>,

L<SSL_CTX_load_verify_locations(3)>

=head1 COPYRIGHT

Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.

Copyright 2000-2018 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

=pod

=head1 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

=head1 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);

=head1 DESCRIPTION

SSL_CTX_set_client_CA_list() sets the B<list> of CAs sent to the client when

requesting a client certificate for B<ctx>.

SSL_set_client_CA_list() sets the B<list> of CAs sent to the client when

requesting a client certificate for the chosen B<ssl>, overriding the

setting valid for B<ssl>'s SSL_CTX object.

SSL_CTX_add_client_CA() adds the CA name extracted from B<cacert> to the

list of CAs sent to the client when requesting a client certificate for

B<ctx>.

SSL_add_client_CA() adds the CA name extracted from B<cacert> to the

list of CAs sent to the client when requesting a client certificate for

the chosen B<ssl>, overriding the setting valid for B<ssl>'s SSL_CTX object.

=head1 NOTES

These functions are similar to L<SSL_CTX_set0_CA_list(3)> and similar functions

but only have an effect on the server side. These functions are present for

backwards compatibility. L<SSL_CTX_set0_CA_list(3)> and similar functions should

be used in preference.

When a TLS/SSL server requests a client certificate (see

B<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

B<ctx> and SSL_set_client_CA_list() for the specific B<ssl>. The list

specified overrides the previous setting. The CAs listed do not become

trusted (B<list> only contains the names, not the complete certificates); use

L<SSL_CTX_load_verify_locations(3)>

to additionally load them for verification.

If the list of acceptable CAs is compiled in a file, the

L<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 B<ctx> or B<ssl> (as appropriate) is opened.

These functions are only useful for TLS/SSL servers.

=head1 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:

=over 4

=item Z<>0

A failure while manipulating the STACK_OF(X509_NAME) object occurred or

the X509_NAME could not be extracted from B<cacert>. Check the error stack

to find out the reason.

=item Z<>1

The operation succeeded.

=back

=head1 EXAMPLES

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

 SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(CAfile));

=head1 SEE ALSO

L<ssl(7)>,

L<SSL_get_client_CA_list(3)>,

L<SSL_load_client_CA_file(3)>,

L<SSL_CTX_load_verify_locations(3)>

=head1 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

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

=cut

=pod

=head1 NAME

SSL_get_client_CA_list, SSL_CTX_get_client_CA_list - get list of client CAs

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 STACK_OF(X509_NAME) *SSL_get_client_CA_list(const SSL *s);

 STACK_OF(X509_NAME) *SSL_CTX_get_client_CA_list(const SSL_CTX *ctx);

=head1 DESCRIPTION

SSL_CTX_get_client_CA_list() returns the list of client CAs explicitly set for

B<ctx> using L<SSL_CTX_set_client_CA_list(3)>.

SSL_get_client_CA_list() returns the list of client CAs explicitly

set for B<ssl> using SSL_set_client_CA_list() or B<ssl>'s SSL_CTX object with

L<SSL_CTX_set_client_CA_list(3)>, when in

server mode. In client mode, SSL_get_client_CA_list returns the list of

client CAs sent from the server, if any.

=head1 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:

=over 4

=item STACK_OF(X509_NAMES)

List of CA names explicitly set (for B<ctx> or in server mode) or send

by the server (client mode).

=item NULL

No client CA list was explicitly set (for B<ctx> or in server mode) or

the server did not send a list of CAs (client mode).

=back

=head1 SEE ALSO

L<ssl(7)>,

L<SSL_CTX_set_client_CA_list(3)>,

L<SSL_CTX_set_client_cert_cb(3)>

=head1 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

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

=cut