/*

 * Copyright (C) 2018 Red Hat, Inc.

 *

 * Author: Daiki Ueno

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

/* This file contains the code for the Early Data TLS 1.3 extension.

 */

#include "gnutls_int.h"

#include "errors.h"

#include "num.h"

#include "hello_ext_lib.h"

#include <ext/early_data.h>

static int early_data_recv_params(gnutls_session_t session,

				  const uint8_t * data,

				  size_t data_size);

static int early_data_send_params(gnutls_session_t session,

				  gnutls_buffer_st * extdata);

const hello_ext_entry_st ext_mod_early_data = {

	.name = "Early Data",

	.tls_id = 42,

	.gid = GNUTLS_EXTENSION_EARLY_DATA,

	.validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_CLIENT_HELLO | GNUTLS_EXT_FLAG_EE,

	.client_parse_point = GNUTLS_EXT_MANDATORY, /* force parsing prior to EXT_TLS extensions */

	.server_parse_point = GNUTLS_EXT_MANDATORY, /* force parsing prior to EXT_TLS extensions */

	.recv_func = early_data_recv_params,

	.send_func = early_data_send_params,

	.pack_func = NULL,

	.unpack_func = NULL,

	.deinit_func = _gnutls_hello_ext_default_deinit,

	.cannot_be_overriden = 0

};

static int

early_data_recv_params(gnutls_session_t session,

		       const uint8_t * data, size_t _data_size)

{

	const version_entry_st *vers = get_version(session);

	if (!vers || !vers->tls13_sem)

		return gnutls_assert_val(0);

	if (session->security_parameters.entity == GNUTLS_SERVER) {

		/* The flag may be cleared by pre_shared_key

		 * extension, when replay is detected. */

		if ((session->internals.flags & GNUTLS_ENABLE_EARLY_DATA) &&

		    /* Refuse early data when this is a second CH after HRR */

		    !(session->internals.hsk_flags & HSK_HRR_SENT))

			session->internals.hsk_flags |= HSK_EARLY_DATA_ACCEPTED;

		session->internals.hsk_flags |= HSK_EARLY_DATA_IN_FLIGHT;

	} else {

		if (_gnutls_ext_get_msg(session) == GNUTLS_EXT_FLAG_EE)

			session->internals.hsk_flags |= HSK_EARLY_DATA_ACCEPTED;

	}

	return 0;

}

/* returns data_size or a negative number on failure

 */

static int

early_data_send_params(gnutls_session_t session,

		       gnutls_buffer_st * extdata)

{

	if (session->security_parameters.entity == GNUTLS_SERVER) {

		if (session->internals.hsk_flags & HSK_EARLY_DATA_ACCEPTED)

			return GNUTLS_E_INT_RET_0;

	} else {

		if (session->internals.early_data_presend_buffer.length > 0) {

			session->internals.hsk_flags |= HSK_EARLY_DATA_IN_FLIGHT;

			return GNUTLS_E_INT_RET_0;

		}

	}

	return 0;

}

/**

 * gnutls_record_get_max_early_data_size:

 * @session: is a #gnutls_session_t type.

 *

 * This function returns the maximum early data size in this connection.

 * This property can only be set to servers.  The client may be

 * provided with the maximum allowed size through the "early_data"

 * extension of the NewSessionTicket handshake message.

 *

 * Returns: The maximum early data size in this connection.

 *

 * Since: 3.6.5

 **/

size_t

gnutls_record_get_max_early_data_size(gnutls_session_t session)

{

	return session->security_parameters.max_early_data_size;

}

/**

 * gnutls_record_set_max_early_data_size:

 * @session: is a #gnutls_session_t type.

 * @size: is the new size

 *

 * This function sets the maximum early data size in this connection.

 * This property can only be set to servers.  The client may be

 * provided with the maximum allowed size through the "early_data"

 * extension of the NewSessionTicket handshake message.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since: 3.6.4

 **/

int

gnutls_record_set_max_early_data_size(gnutls_session_t session,

				      size_t size)

{

	if (session->security_parameters.entity == GNUTLS_CLIENT)

		return GNUTLS_E_INVALID_REQUEST;

	/* Reject zero as well, as it is useless. */

	if (size == 0 || size > UINT32_MAX)

		return GNUTLS_E_INVALID_REQUEST;

	session->security_parameters.max_early_data_size = (uint32_t) size;

	return 0;

}