= nng_tls_config_ca_chain(3tls)
//
// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
//
// This document is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt).  A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//

== NAME

nng_tls_config_ca_chain - configure certificate authority certificate chain

== SYNOPSIS

[source, c]
----
#include <nng/nng.h>
#include <nng/supplemental/tls/tls.h>

int nng_tls_config_ca_chain(nng_tls_config *cfg, const char *chain, const char *crl);
----

== DESCRIPTION

The `nng_tls_config_ca_chain()` function configures a certificate or
((certificate chain)) to be used when validating peers using the configuration
_cfg_.

NOTE: Certificates *must* be configured when using the authentication mode
`NNG_TLS_AUTH_MODE_REQUIRED`.

TIP: This function may be called multiple times, to add additional chains
to a configuration, without affecting those added previously.

The certificates located in _chain_ must be a zero-terminated C string in
https://tools.ietf.org/html/rfc7468[PEM] format.
Multiple certificates may appear concatenated together,
with the leaf certificate listed first.

The _crl_ may be `NULL`, or may also be a C string containing a PEM format
((certificate revocation list)) for the associated authority.

== RETURN VALUES

This function returns 0 on success, and non-zero otherwise.

== ERRORS

[horizontal]
`NNG_ENOMEM`:: Insufficient memory is available.
`NNG_EBUSY`:: The configuration _cfg_ is already in use, and cannot be modified.
`NNG_EINVAL`:: An invalid _chain_ or _crl_ was supplied.

== SEE ALSO

[.text-left]
xref:nng_strerror.3.adoc[nng_strerror(3)],
xref:nng_tls_config_alloc.3tls.adoc[nng_tls_config_alloc(.3tls)],
xref:nng_tls_config_auth_mode.3tls.adoc[nng_tls_config_auth_mode(.3tls)],
xref:nng_tls_config_ca_file.3tls.adoc[nng_tls_config_ca_file(.3tls)],
xref:nng.7.adoc[nng(7)]
