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
#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);
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 ssls 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 ssls SSL_CTX object.
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(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.
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. 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.
Scan all certificates in CAfile and list them as acceptable CAs:
ssl(3), SSL_get_client_CA_list(3), SSL_load_client_CA_file(3), SSL_CTX_load_verify_locations(3)