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/*
* Copyright (C) 2001-2012 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 <http://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/supported_versions.h>
static int supported_versions_recv_params(gnutls_session_t session,
const uint8_t * data,
size_t data_size);
static int supported_versions_send_params(gnutls_session_t session,
gnutls_buffer_st * extdata);
const hello_ext_entry_st ext_mod_supported_versions = {
.name = "Supported Versions",
.tls_id = 43,
.gid = GNUTLS_EXTENSION_SUPPORTED_VERSIONS,
.validity = GNUTLS_EXT_FLAG_CLIENT_HELLO,
.parse_type = GNUTLS_EXT_MANDATORY, /* force parsing prior to EXT_TLS extensions */
.recv_func = supported_versions_recv_params,
.send_func = supported_versions_send_params,
.pack_func = NULL,
.unpack_func = NULL,
.deinit_func = NULL,
.cannot_be_overriden = 1
};
/* Only client sends this extension. */
static int
supported_versions_recv_params(gnutls_session_t session,
const uint8_t * data, size_t _data_size)
{
ssize_t data_size = _data_size;
uint8_t major, minor;
gnutls_protocol_t proto;
ssize_t bytes;
int ret;
if (session->security_parameters.entity == GNUTLS_SERVER) {
DECR_LEN(data_size, 1);
bytes = data[0];
data++;
if (bytes % 2 == 1)
return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
DECR_LEN(data_size, bytes);
if (data_size != 0)
return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
while (bytes > 0) {
major = data[0];
minor = data[1];
data += 2;
bytes -= 2;
proto = _gnutls_version_get(major, minor);
_gnutls_handshake_log("EXT[%p]: Found version: %d.%d\n",
session, (int)major, (int)minor);
if (_gnutls_version_is_supported(session, proto)) {
ret = _gnutls_set_current_version(session, proto);
if (ret < 0)
return gnutls_assert_val(ret);
_gnutls_handshake_log("EXT[%p]: Negotiated version: %d.%d\n",
session, (int)major, (int)minor);
return 0;
}
}
/* if we are here, none of the versions were acceptable */
return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_VERSION_PACKET);
} else {
/* a server should never send this message */
gnutls_assert();
return GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION;
}
return 0;
}
/* returns data_size or a negative number on failure
*/
static int
supported_versions_send_params(gnutls_session_t session,
gnutls_buffer_st * extdata)
{
uint8_t versions[32];
size_t versions_size;
int ret;
/* this function sends the client extension data (dnsname) */
if (session->security_parameters.entity == GNUTLS_CLIENT) {
ret = _gnutls_write_supported_versions(session, versions, sizeof(versions));
if (ret <= 0) /* if this function doesn't succeed do not send anything */
return 0;
versions_size = ret;
ret = _gnutls_buffer_append_data_prefix(extdata, 8, versions, versions_size);
if (ret < 0)
return gnutls_assert_val(ret);
return versions_size+2;
}
return 0;
}
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