s2n_server_hello_recv_test.c

/*
 * 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.
 */

/* Target Functions: s2n_server_hello_recv s2n_server_extensions_recv s2n_server_hello_retry_recv
                     s2n_connection_get_cipher_preferences s2n_set_cipher_as_client */

#include <stdint.h>

#include <openssl/crypto.h>
#include <openssl/err.h>

#include "api/s2n.h"
#include "stuffer/s2n_stuffer.h"
#include "tls/s2n_connection.h"
#include "tls/s2n_tls.h"
#include "utils/s2n_safety.h"
#include "s2n_test.h"

static const uint8_t TLS_VERSIONS[] = {S2N_TLS10, S2N_TLS11, S2N_TLS12, S2N_TLS13};
struct s2n_config *client_config;

int s2n_fuzz_test(const uint8_t *buf, size_t len)
{
    /* We need at least one byte of input to set parameters */
    S2N_FUZZ_ENSURE_MIN_LEN(len, 1);

    /* Setup */
    client_config = s2n_config_new();
    struct s2n_connection *client_conn = s2n_connection_new(S2N_CLIENT);
    POSIX_GUARD(s2n_connection_set_config(client_conn, client_config));
    POSIX_ENSURE_REF(client_conn);
    POSIX_GUARD(s2n_stuffer_write_bytes(&client_conn->handshake.io, buf, len));

    /* Pull a byte off the libfuzzer input and use it to set parameters */
    uint8_t randval = 0;
    POSIX_GUARD(s2n_stuffer_read_uint8(&client_conn->handshake.io, &randval));
    client_conn->client_protocol_version = TLS_VERSIONS[(randval & 0x0f) % s2n_array_len(TLS_VERSIONS)];
    client_conn->server_protocol_version = TLS_VERSIONS[(randval >> 4) % s2n_array_len(TLS_VERSIONS)];
    /* Run Test
     * Do not use GUARD macro here since the connection memory hasn't been freed.
     */
    s2n_server_hello_recv(client_conn);

    /* Cleanup */
    POSIX_GUARD(s2n_config_free(client_config));
    POSIX_GUARD(s2n_connection_free(client_conn));

    return S2N_SUCCESS;
}

S2N_FUZZ_TARGET(NULL, s2n_fuzz_test, NULL)