.\" $OpenBSD: SSL_CTX_set_client_CA_list.3,v 1.6 2020/03/30 10:28:59 schwarze Exp $ .\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 .\" .\" This file was written by Lutz Jaenicke . .\" Copyright (c) 2000, 2001, 2013 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. 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Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: March 30 2020 $ .Dt SSL_CTX_SET_CLIENT_CA_LIST 3 .Os .Sh NAME .Nm SSL_CTX_set_client_CA_list , .Nm SSL_set_client_CA_list , .Nm SSL_CTX_add_client_CA , .Nm SSL_add_client_CA .Nd set list of CAs sent to the client when requesting a client certificate .Sh SYNOPSIS .In openssl/ssl.h .Ft void .Fn SSL_CTX_set_client_CA_list "SSL_CTX *ctx" "STACK_OF(X509_NAME) *list" .Ft void .Fn SSL_set_client_CA_list "SSL *s" "STACK_OF(X509_NAME) *list" .Ft int .Fn SSL_CTX_add_client_CA "SSL_CTX *ctx" "X509 *cacert" .Ft int .Fn SSL_add_client_CA "SSL *ssl" "X509 *cacert" .Sh DESCRIPTION .Fn SSL_CTX_set_client_CA_list sets the .Fa list of CAs sent to the client when requesting a client certificate for .Fa ctx . .Pp .Fn SSL_set_client_CA_list sets the .Fa list of CAs sent to the client when requesting a client certificate for the chosen .Fa ssl , overriding the setting valid for .Fa ssl Ns 's .Vt SSL_CTX object. .Pp .Fn SSL_CTX_add_client_CA adds the CA name extracted from .Fa cacert to the list of CAs sent to the client when requesting a client certificate for .Fa ctx . .Pp .Fn SSL_add_client_CA adds the CA name extracted from .Fa cacert to the list of CAs sent to the client when requesting a client certificate for the chosen .Fa ssl , overriding the setting valid for .Fa ssl Ns 's .Va SSL_CTX object. .Pp When a TLS/SSL server requests a client certificate (see .Fn SSL_CTX_set_verify ) , it sends a list of CAs for which it will accept certificates to the client. .Pp This list must explicitly be set using .Fn SSL_CTX_set_client_CA_list for .Fa ctx and .Fn SSL_set_client_CA_list for the specific .Fa ssl . The list specified overrides the previous setting. The CAs listed do not become trusted .Po .Fa list only contains the names, not the complete certificates .Pc ; use .Xr SSL_CTX_load_verify_locations 3 to additionally load them for verification. .Pp If the list of acceptable CAs is compiled in a file, the .Xr SSL_load_client_CA_file 3 function can be used to help importing the necessary data. .Pp .Fn SSL_CTX_add_client_CA and .Fn SSL_add_client_CA can be used to add additional items the list of client CAs. If no list was specified before using .Fn SSL_CTX_set_client_CA_list or .Fn SSL_set_client_CA_list , a new client CA list for .Fa ctx or .Fa ssl (as appropriate) is opened. .Pp These functions are only useful for TLS/SSL servers. .Sh RETURN VALUES .Fn SSL_CTX_add_client_CA and .Fn SSL_add_client_CA have the following return values: .Bl -tag -width Ds .It 0 A failure while manipulating the .Dv STACK_OF Ns .Pq Vt X509_NAME object occurred or the .Vt X509_NAME could not be extracted from .Fa cacert . Check the error stack to find out the reason. .It 1 The operation succeeded. .El .Sh EXAMPLES Scan all certificates in .Fa CAfile and list them as acceptable CAs: .Bd -literal SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(CAfile)); .Ed .Sh SEE ALSO .Xr ssl 3 , .Xr SSL_CTX_load_verify_locations 3 , .Xr SSL_get_client_CA_list 3 , .Xr SSL_load_client_CA_file 3 , .Xr X509_NAME_new 3 .Sh HISTORY .Fn SSL_CTX_set_client_CA_list , .Fn SSL_set_client_CA_list , .Fn SSL_CTX_add_client_CA , and .Fn SSL_add_client_CA first appeared in SSLeay 0.8.0 and have been available since .Ox 2.4 .