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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include "tls/extensions/s2n_ec_point_format.h"
#include <stdint.h>
#include <sys/param.h>
#include "tls/extensions/s2n_client_supported_groups.h"
#include "tls/s2n_tls.h"
#include "utils/s2n_safety.h"
static int s2n_ec_point_format_send(struct s2n_connection *conn, struct s2n_stuffer *out);
static int s2n_ec_point_format_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
const s2n_extension_type s2n_client_ec_point_format_extension = {
.iana_value = TLS_EXTENSION_EC_POINT_FORMATS,
.is_response = false,
.send = s2n_ec_point_format_send,
.recv = s2n_ec_point_format_recv,
.should_send = s2n_extension_should_send_if_ecc_enabled,
.if_missing = s2n_extension_noop_if_missing,
};
static bool s2n_server_ec_point_format_should_send(struct s2n_connection *conn);
const s2n_extension_type s2n_server_ec_point_format_extension = {
.iana_value = TLS_EXTENSION_EC_POINT_FORMATS,
.is_response = true,
.send = s2n_ec_point_format_send,
.recv = s2n_extension_recv_noop,
.should_send = s2n_server_ec_point_format_should_send,
.if_missing = s2n_extension_noop_if_missing,
};
static bool s2n_server_ec_point_format_should_send(struct s2n_connection *conn)
{
return conn && conn->secure && conn->secure->cipher_suite
&& s2n_kex_includes(conn->secure->cipher_suite->key_exchange_alg, &s2n_ecdhe);
}
static int s2n_ec_point_format_send(struct s2n_connection *conn, struct s2n_stuffer *out)
{
/* Point format list len. We only support one. */
POSIX_GUARD(s2n_stuffer_write_uint8(out, 1));
/* Only allow uncompressed format */
POSIX_GUARD(s2n_stuffer_write_uint8(out, TLS_EC_POINT_FORMAT_UNCOMPRESSED));
return S2N_SUCCESS;
}
static int s2n_ec_point_format_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
/* Only uncompressed points are supported by the server and the client must include it in
* the extension. Just skip the extension.
*
*= https://tools.ietf.org/rfc/rfc8422#section-5.1.2
*= type=exception
*= reason=Incorrect implementations exist in the wild. Skipping validation.
*# If the client sends the extension and the extension does not contain
*# the uncompressed point format, and the client has used the Supported
*# Groups extension to indicate support for any of the curves defined in
*# this specification, then the server MUST abort the handshake and
*# return an illegal_parameter alert.
*/
conn->ec_point_formats = 1;
return S2N_SUCCESS;
}
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