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.\"
.IX Title "SSL_CTX_set_client_CA_list 3"
.TH SSL_CTX_set_client_CA_list 3 2019-12-20 1.0.2u OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH 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
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #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);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\fBSSL_CTX_set_client_CA_list()\fR sets the \fBlist\fR of CAs sent to the client when
requesting a client certificate for \fBctx\fR.
.PP
\&\fBSSL_set_client_CA_list()\fR sets the \fBlist\fR of CAs sent to the client when
requesting a client certificate for the chosen \fBssl\fR, overriding the
setting valid for \fBssl\fR's SSL_CTX object.
.PP
\&\fBSSL_CTX_add_client_CA()\fR adds the CA name extracted from \fBcacert\fR to the
list of CAs sent to the client when requesting a client certificate for
\&\fBctx\fR.
.PP
\&\fBSSL_add_client_CA()\fR adds the CA name extracted from \fBcacert\fR to the
list of CAs sent to the client when requesting a client certificate for
the chosen \fBssl\fR, overriding the setting valid for \fBssl\fR's SSL_CTX object.
.SH NOTES
.IX Header "NOTES"
When a TLS/SSL server requests a client certificate (see
\&\fBSSL_CTX_set_verify\|(3)\fR), it sends a list of CAs, for which
it will accept certificates, to the client.
.PP
This list must explicitly be set using \fBSSL_CTX_set_client_CA_list()\fR for
\&\fBctx\fR and \fBSSL_set_client_CA_list()\fR for the specific \fBssl\fR. The list
specified overrides the previous setting. The CAs listed do not become
trusted (\fBlist\fR only contains the names, not the complete certificates); use
\&\fBSSL_CTX_load_verify_locations\fR\|(3) 
to additionally load them for verification.
.PP
If the list of acceptable CAs is compiled in a file, the
\&\fBSSL_load_client_CA_file\fR\|(3)
function can be used to help importing the necessary data.
.PP
\&\fBSSL_CTX_add_client_CA()\fR and \fBSSL_add_client_CA()\fR can be used to add additional
items the list of client CAs. If no list was specified before using
\&\fBSSL_CTX_set_client_CA_list()\fR or \fBSSL_set_client_CA_list()\fR, a new client
CA list for \fBctx\fR or \fBssl\fR (as appropriate) is opened.
.PP
These functions are only useful for TLS/SSL servers.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBSSL_CTX_set_client_CA_list()\fR and \fBSSL_set_client_CA_list()\fR do not return
diagnostic information.
.PP
\&\fBSSL_CTX_add_client_CA()\fR and \fBSSL_add_client_CA()\fR have the following return
values:
.IP 0 4
A failure while manipulating the STACK_OF(X509_NAME) object occurred or
the X509_NAME could not be extracted from \fBcacert\fR. Check the error stack
to find out the reason.
.IP 1 4
.IX Item "1"
The operation succeeded.
.SH EXAMPLES
.IX Header "EXAMPLES"
Scan all certificates in \fBCAfile\fR and list them as acceptable CAs:
.PP
.Vb 1
\&  SSL_CTX_set_client_CA_list(ctx,SSL_load_client_CA_file(CAfile));
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBssl\fR\|(3),
\&\fBSSL_get_client_CA_list\fR\|(3),
\&\fBSSL_load_client_CA_file\fR\|(3),
\&\fBSSL_CTX_load_verify_locations\fR\|(3)