- NAME
- SYNOPSIS
- DESCRIPTION
- NOTES
- RETURN VALUES
- EXAMPLES
- SEE ALSO

# 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_options()), 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 to additionally load them for verification.

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

1. The operation succeeded.

2. 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.

# 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, SSL_get_client_CA_list, SSL_load_client_CA_file, SSL_CTX_load_verify_locations