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/*
* Copyright (C) 2011-2012 Free Software Foundation, Inc.
* Copyright (C) 2017 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 Elliptic Curve Point Formats extension.
*/
#include "ext/ec_point_formats.h"
#include "str.h"
#include "state.h"
#include <gnutls/gnutls.h>
static int _gnutls_supported_ec_point_formats_recv_params(gnutls_session_t session,
const uint8_t * data,
size_t data_size);
static int _gnutls_supported_ec_point_formats_send_params(gnutls_session_t session,
gnutls_buffer_st * extdata);
const hello_ext_entry_st ext_mod_supported_ec_point_formats = {
.name = "Supported EC Point Formats",
.tls_id = 11,
.gid = GNUTLS_EXTENSION_SUPPORTED_EC_POINT_FORMATS,
.client_parse_point = GNUTLS_EXT_TLS,
.server_parse_point = GNUTLS_EXT_TLS,
.validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_DTLS |
GNUTLS_EXT_FLAG_CLIENT_HELLO | GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO,
.recv_func = _gnutls_supported_ec_point_formats_recv_params,
.send_func = _gnutls_supported_ec_point_formats_send_params,
.pack_func = NULL,
.unpack_func = NULL,
.deinit_func = NULL
};
/* Receive point formats
*/
static int
_gnutls_supported_ec_point_formats_recv_params(gnutls_session_t session,
const uint8_t * data,
size_t data_size)
{
size_t len, i;
int uncompressed = 0;
if (session->security_parameters.entity == GNUTLS_CLIENT) {
if (data_size < 1)
return
gnutls_assert_val
(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);
len = data[0];
if (len < 1)
return
gnutls_assert_val
(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);
DECR_LEN(data_size, len + 1);
for (i = 1; i <= len; i++)
if (data[i] == 0) { /* uncompressed */
uncompressed = 1;
break;
}
if (uncompressed == 0)
return
gnutls_assert_val
(GNUTLS_E_UNKNOWN_PK_ALGORITHM);
} else {
/* only sanity check here. We only support uncompressed points
* and a client must support it thus nothing to check.
*/
if (data_size < 1)
return
gnutls_assert_val
(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);
}
return 0;
}
/* returns data_size or a negative number on failure
*/
static int
_gnutls_supported_ec_point_formats_send_params(gnutls_session_t session,
gnutls_buffer_st * extdata)
{
const uint8_t p[2] = { 0x01, 0x00 }; /* only support uncompressed point format */
int ret;
if (session->security_parameters.entity == GNUTLS_SERVER
&& !_gnutls_session_is_ecc(session))
return 0;
if (session->internals.priorities->groups.size > 0) {
ret = _gnutls_buffer_append_data(extdata, p, 2);
if (ret < 0)
return gnutls_assert_val(ret);
return 2;
}
return 0;
}
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