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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 "api/s2n.h"
#include "tls/s2n_alerts.h"
#include "tls/s2n_connection.h"
#include "utils/s2n_safety.h"
S2N_RESULT s2n_client_hello_request_validate(struct s2n_connection *conn)
{
RESULT_ENSURE_REF(conn);
if (IS_NEGOTIATED(conn)) {
RESULT_ENSURE(conn->actual_protocol_version < S2N_TLS13, S2N_ERR_BAD_MESSAGE);
}
/*
*= https://tools.ietf.org/rfc/rfc5246#section-7.4.1.1
*# The HelloRequest message MAY be sent by the server at any time.
*/
RESULT_ENSURE(conn->mode == S2N_CLIENT, S2N_ERR_BAD_MESSAGE);
return S2N_RESULT_OK;
}
S2N_RESULT s2n_client_hello_request_recv(struct s2n_connection *conn)
{
RESULT_ENSURE_REF(conn);
RESULT_ENSURE_REF(conn->config);
RESULT_GUARD(s2n_client_hello_request_validate(conn));
/* Maintain the old s2n-tls behavior by default.
* Traditionally, s2n-tls has just ignored all hello requests.
*/
if (!conn->config->renegotiate_request_cb) {
return S2N_RESULT_OK;
}
/*
*= https://tools.ietf.org/rfc/rfc5746#section-4.2
*# This text applies if the connection's "secure_renegotiation" flag is
*# set to FALSE.
*#
*# It is possible that un-upgraded servers will request that the client
*# renegotiate. It is RECOMMENDED that clients refuse this
*# renegotiation request. Clients that do so MUST respond to such
*# requests with a "no_renegotiation" alert (RFC 5246 requires this
*# alert to be at the "warning" level). It is possible that the
*# apparently un-upgraded server is in fact an attacker who is then
*# allowing the client to renegotiate with a different, legitimate,
*# upgraded server.
*/
if (!conn->secure_renegotiation) {
RESULT_GUARD(s2n_queue_reader_no_renegotiation_alert(conn));
return S2N_RESULT_OK;
}
s2n_renegotiate_response response = S2N_RENEGOTIATE_REJECT;
int result = conn->config->renegotiate_request_cb(conn, conn->config->renegotiate_request_ctx, &response);
RESULT_ENSURE(result == S2N_SUCCESS, S2N_ERR_CANCELLED);
/*
*= https://tools.ietf.org/rfc/rfc5246#section-7.4.1.1
*# This message MAY be ignored by
*# the client if it does not wish to renegotiate a session, or the
*# client may, if it wishes, respond with a no_renegotiation alert.
*/
if (response == S2N_RENEGOTIATE_REJECT) {
RESULT_GUARD(s2n_queue_reader_no_renegotiation_alert(conn));
return S2N_RESULT_OK;
}
return S2N_RESULT_OK;
}
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