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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_alpn.h"
#include <stdint.h>
#include <sys/param.h>
#include "tls/extensions/s2n_extension_type.h"
#include "tls/s2n_protocol_preferences.h"
#include "tls/s2n_tls.h"
#include "tls/s2n_tls_parameters.h"
#include "utils/s2n_safety.h"
bool s2n_client_alpn_should_send(struct s2n_connection *conn);
static int s2n_client_alpn_send(struct s2n_connection *conn, struct s2n_stuffer *out);
static int s2n_client_alpn_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
const s2n_extension_type s2n_client_alpn_extension = {
.iana_value = TLS_EXTENSION_ALPN,
.is_response = false,
.send = s2n_client_alpn_send,
.recv = s2n_client_alpn_recv,
.should_send = s2n_client_alpn_should_send,
.if_missing = s2n_extension_noop_if_missing,
};
bool s2n_client_alpn_should_send(struct s2n_connection *conn)
{
struct s2n_blob *client_app_protocols;
return s2n_connection_get_protocol_preferences(conn, &client_app_protocols) == S2N_SUCCESS
&& client_app_protocols->size != 0 && client_app_protocols->data != NULL;
}
static int s2n_client_alpn_send(struct s2n_connection *conn, struct s2n_stuffer *out)
{
struct s2n_blob *client_app_protocols;
POSIX_GUARD(s2n_connection_get_protocol_preferences(conn, &client_app_protocols));
POSIX_ENSURE_REF(client_app_protocols);
POSIX_GUARD(s2n_stuffer_write_uint16(out, client_app_protocols->size));
POSIX_GUARD(s2n_stuffer_write(out, client_app_protocols));
return S2N_SUCCESS;
}
static int s2n_client_alpn_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
struct s2n_blob *supported_protocols = NULL;
POSIX_GUARD(s2n_connection_get_protocol_preferences(conn, &supported_protocols));
POSIX_ENSURE_REF(supported_protocols);
if (supported_protocols->size == 0) {
/* No protocols configured, nothing to do */
return S2N_SUCCESS;
}
uint16_t wire_size = 0;
POSIX_GUARD(s2n_stuffer_read_uint16(extension, &wire_size));
if (wire_size > s2n_stuffer_data_available(extension) || wire_size < 3) {
/* Malformed length, ignore the extension */
return S2N_SUCCESS;
}
struct s2n_blob client_protocols = { 0 };
POSIX_GUARD(s2n_blob_init(&client_protocols, s2n_stuffer_raw_read(extension, wire_size), wire_size));
struct s2n_stuffer server_protocols = { 0 };
POSIX_GUARD(s2n_stuffer_init(&server_protocols, supported_protocols));
POSIX_GUARD(s2n_stuffer_skip_write(&server_protocols, supported_protocols->size));
POSIX_GUARD_RESULT(s2n_select_server_preference_protocol(conn, &server_protocols, &client_protocols));
return S2N_SUCCESS;
}
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