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/*
* Copyright (C) 2014 Red Hat, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* 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 Max Record Size TLS extension.
*/
#include "gnutls_int.h"
#include "errors.h"
#include "num.h"
#include "hello_ext.h"
#include "ext/etm.h"
static int _gnutls_ext_etm_recv_params(gnutls_session_t session,
const uint8_t *data, size_t data_size);
static int _gnutls_ext_etm_send_params(gnutls_session_t session,
gnutls_buffer_st *extdata);
const hello_ext_entry_st ext_mod_etm = {
.name = "Encrypt-then-MAC",
.tls_id = 22,
.gid = GNUTLS_EXTENSION_ETM,
.client_parse_point = GNUTLS_EXT_MANDATORY,
.server_parse_point = GNUTLS_EXT_MANDATORY,
.validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_DTLS |
GNUTLS_EXT_FLAG_CLIENT_HELLO |
GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO,
.recv_func = _gnutls_ext_etm_recv_params,
.send_func = _gnutls_ext_etm_send_params,
.pack_func = NULL,
.unpack_func = NULL,
.deinit_func = NULL,
.cannot_be_overriden = 1
};
/*
* In case of a server: if an EXT_MASTER_SECRET extension type is received then it
* sets a flag into the session security parameters.
*
*/
static int _gnutls_ext_etm_recv_params(gnutls_session_t session,
const uint8_t *data, size_t _data_size)
{
ssize_t data_size = _data_size;
if (data_size != 0) {
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
}
if (session->security_parameters.entity == GNUTLS_SERVER) {
gnutls_ext_priv_data_t epriv;
if (session->internals.no_etm != 0)
return 0;
epriv = (void *)(intptr_t)1;
_gnutls_hello_ext_set_priv(session, GNUTLS_EXTENSION_ETM,
epriv);
/* don't decide now, decide on send */
return 0;
} else { /* client */
const gnutls_cipher_suite_entry_st *e =
session->security_parameters.cs;
if (e != NULL) {
const cipher_entry_st *c;
c = cipher_to_entry(e->block_algorithm);
if (c == NULL || (c->type == CIPHER_AEAD ||
c->type == CIPHER_STREAM))
return 0;
session->security_parameters.etm = 1;
}
}
return 0;
}
/* returns data_size or a negative number on failure
*/
static int _gnutls_ext_etm_send_params(gnutls_session_t session,
gnutls_buffer_st *extdata)
{
if (session->internals.no_etm != 0)
return 0;
/* this function sends the client extension data */
if (session->security_parameters.entity == GNUTLS_CLIENT) {
if (session->internals.priorities->have_cbc != 0)
return GNUTLS_E_INT_RET_0;
else
return 0;
} else { /* server side */
const gnutls_cipher_suite_entry_st *e;
const cipher_entry_st *c;
int ret;
gnutls_ext_priv_data_t epriv;
e = session->security_parameters.cs;
if (e != NULL) {
c = cipher_to_entry(e->block_algorithm);
if (c == NULL || (c->type == CIPHER_AEAD ||
c->type == CIPHER_STREAM))
return 0;
ret = _gnutls_hello_ext_get_priv(
session, GNUTLS_EXTENSION_ETM, &epriv);
if (ret < 0 || ((intptr_t)epriv) == 0)
return 0;
session->security_parameters.etm = 1;
return GNUTLS_E_INT_RET_0;
}
}
return 0;
}
/**
* gnutls_session_etm_status:
* @session: is a #gnutls_session_t type.
*
* Get the status of the encrypt-then-mac extension negotiation.
* This is in accordance to rfc7366
*
* Returns: Non-zero if the negotiation was successful or zero otherwise.
**/
unsigned gnutls_session_etm_status(gnutls_session_t session)
{
return session->security_parameters.etm;
}
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