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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_client_server_name.h"
#include <stdint.h>
#include <sys/param.h>
#include "tls/s2n_tls.h"
#include "tls/s2n_tls_parameters.h"
#include "utils/s2n_safety.h"
#define S2N_NAME_TYPE_HOST_NAME 0
static bool s2n_client_server_name_should_send(struct s2n_connection *conn);
static int s2n_client_server_name_send(struct s2n_connection *conn, struct s2n_stuffer *out);
static int s2n_client_server_name_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
const s2n_extension_type s2n_client_server_name_extension = {
.iana_value = TLS_EXTENSION_SERVER_NAME,
.is_response = false,
.send = s2n_client_server_name_send,
.recv = s2n_client_server_name_recv,
.should_send = s2n_client_server_name_should_send,
.if_missing = s2n_extension_noop_if_missing,
};
static bool s2n_client_server_name_should_send(struct s2n_connection *conn)
{
return conn && conn->server_name[0] != '\0';
}
static int s2n_client_server_name_send(struct s2n_connection *conn, struct s2n_stuffer *out)
{
struct s2n_stuffer_reservation server_name_list_size = { 0 };
POSIX_GUARD(s2n_stuffer_reserve_uint16(out, &server_name_list_size));
/* NameType, as described by RFC6066.
* host_name is currently the only possible NameType defined. */
POSIX_GUARD(s2n_stuffer_write_uint8(out, S2N_NAME_TYPE_HOST_NAME));
POSIX_GUARD(s2n_stuffer_write_uint16(out, strlen(conn->server_name)));
POSIX_GUARD(s2n_stuffer_write_bytes(out, (const uint8_t *) conn->server_name, strlen(conn->server_name)));
POSIX_GUARD(s2n_stuffer_write_vector_size(&server_name_list_size));
return S2N_SUCCESS;
}
/* Read the extension up to the first item in ServerNameList. Instantiates the server_name blob to
* point to the first entry. For now s2n ignores all subsequent items in ServerNameList.
*/
S2N_RESULT s2n_client_server_name_parse(struct s2n_stuffer *extension, struct s2n_blob *server_name)
{
uint16_t list_size = 0;
RESULT_GUARD_POSIX(s2n_stuffer_read_uint16(extension, &list_size));
RESULT_ENSURE_LTE(list_size, s2n_stuffer_data_available(extension));
uint8_t server_name_type = 0;
RESULT_GUARD_POSIX(s2n_stuffer_read_uint8(extension, &server_name_type));
RESULT_ENSURE_EQ(server_name_type, S2N_NAME_TYPE_HOST_NAME);
uint16_t length = 0;
RESULT_GUARD_POSIX(s2n_stuffer_read_uint16(extension, &length));
RESULT_ENSURE_LTE(length, s2n_stuffer_data_available(extension));
uint8_t *data = s2n_stuffer_raw_read(extension, length);
RESULT_ENSURE_REF(data);
RESULT_GUARD_POSIX(s2n_blob_init(server_name, data, length));
return S2N_RESULT_OK;
}
static int s2n_client_server_name_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
POSIX_ENSURE_REF(conn);
/* Exit early if we've already parsed the server name */
if (conn->server_name[0]) {
return S2N_SUCCESS;
}
/* Ignore if malformed or we don't have enough space to store it. We just won't use the server name. */
struct s2n_blob server_name = { 0 };
if (!s2n_result_is_ok(s2n_client_server_name_parse(extension, &server_name)) || server_name.size > S2N_MAX_SERVER_NAME) {
return S2N_SUCCESS;
}
POSIX_CHECKED_MEMCPY(conn->server_name, server_name.data, server_name.size);
return S2N_SUCCESS;
}
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