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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 <stdint.h>
#include "error/s2n_errno.h"
#include "stuffer/s2n_stuffer.h"
#include "tls/s2n_cipher_suites.h"
#include "tls/s2n_connection.h"
#include "tls/s2n_tls.h"
#include "utils/s2n_safety.h"
/* From RFC5246 7.1: https://tools.ietf.org/html/rfc5246#section-7.1 */
#define CHANGE_CIPHER_SPEC_TYPE 1
int s2n_basic_ccs_recv(struct s2n_connection *conn)
{
uint8_t type;
POSIX_GUARD(s2n_stuffer_read_uint8(&conn->handshake.io, &type));
S2N_ERROR_IF(type != CHANGE_CIPHER_SPEC_TYPE, S2N_ERR_BAD_MESSAGE);
return 0;
}
int s2n_client_ccs_recv(struct s2n_connection *conn)
{
POSIX_ENSURE_REF(conn);
POSIX_ENSURE_REF(conn->secure);
POSIX_GUARD(s2n_basic_ccs_recv(conn));
/* Zero the sequence number */
struct s2n_blob seq = { 0 };
POSIX_GUARD(s2n_blob_init(&seq, conn->secure->client_sequence_number, sizeof(conn->secure->client_sequence_number)));
POSIX_GUARD(s2n_blob_zero(&seq));
/* Update the client to use the cipher-suite */
conn->client = conn->secure;
/* Flush any partial alert messages that were pending.
* If we don't do this, an attacker can inject a 1-byte alert message into the handshake
* and cause later, valid alerts to be processed incorrectly. */
POSIX_GUARD(s2n_stuffer_wipe(&conn->alert_in));
return 0;
}
int s2n_server_ccs_recv(struct s2n_connection *conn)
{
POSIX_ENSURE_REF(conn);
POSIX_ENSURE_REF(conn->secure);
POSIX_GUARD(s2n_basic_ccs_recv(conn));
/* Zero the sequence number */
struct s2n_blob seq = { 0 };
POSIX_GUARD(s2n_blob_init(&seq, conn->secure->server_sequence_number, sizeof(conn->secure->server_sequence_number)));
POSIX_GUARD(s2n_blob_zero(&seq));
/* Compute the finished message */
POSIX_GUARD(s2n_prf_server_finished(conn));
/* Update the secure state to active, and point the client at the active state */
conn->server = conn->secure;
/* Flush any partial alert messages that were pending.
* If we don't do this, an attacker can inject a 1-byte alert message into the handshake
* and cause later, valid alerts to be processed incorrectly. */
POSIX_GUARD(s2n_stuffer_wipe(&conn->alert_in));
return 0;
}
int s2n_ccs_send(struct s2n_connection *conn)
{
POSIX_GUARD(s2n_stuffer_write_uint8(&conn->handshake.io, CHANGE_CIPHER_SPEC_TYPE));
return 0;
}
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