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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 <sys/param.h>
#include <stdint.h>
#include "tls/extensions/s2n_client_alpn.h"
#include "tls/extensions/s2n_extension_type.h"
#include "tls/s2n_tls.h"
#include "tls/s2n_tls_parameters.h"
#include "utils/s2n_safety.h"
static 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,
};
static 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;
GUARD(s2n_connection_get_protocol_preferences(conn, &client_app_protocols));
notnull_check(client_app_protocols);
GUARD(s2n_stuffer_write_uint16(out, client_app_protocols->size));
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)
{
uint16_t size_of_all;
struct s2n_stuffer client_protos = {0};
struct s2n_stuffer server_protos = {0};
struct s2n_blob *server_app_protocols;
GUARD(s2n_connection_get_protocol_preferences(conn, &server_app_protocols));
if (!server_app_protocols->size) {
/* No protocols configured, nothing to do */
return S2N_SUCCESS;
}
GUARD(s2n_stuffer_read_uint16(extension, &size_of_all));
if (size_of_all > s2n_stuffer_data_available(extension) || size_of_all < 3) {
/* Malformed length, ignore the extension */
return S2N_SUCCESS;
}
struct s2n_blob client_app_protocols = { 0 };
client_app_protocols.size = size_of_all;
client_app_protocols.data = s2n_stuffer_raw_read(extension, size_of_all);
notnull_check(client_app_protocols.data);
/* Find a matching protocol */
GUARD(s2n_stuffer_init(&client_protos, &client_app_protocols));
GUARD(s2n_stuffer_write(&client_protos, &client_app_protocols));
GUARD(s2n_stuffer_init(&server_protos, server_app_protocols));
GUARD(s2n_stuffer_write(&server_protos, server_app_protocols));
while (s2n_stuffer_data_available(&server_protos)) {
uint8_t length;
uint8_t server_protocol[255];
GUARD(s2n_stuffer_read_uint8(&server_protos, &length));
GUARD(s2n_stuffer_read_bytes(&server_protos, server_protocol, length));
while (s2n_stuffer_data_available(&client_protos)) {
uint8_t client_length;
GUARD(s2n_stuffer_read_uint8(&client_protos, &client_length));
S2N_ERROR_IF(client_length > s2n_stuffer_data_available(&client_protos), S2N_ERR_BAD_MESSAGE);
if (client_length != length) {
GUARD(s2n_stuffer_skip_read(&client_protos, client_length));
} else {
uint8_t client_protocol[255];
GUARD(s2n_stuffer_read_bytes(&client_protos, client_protocol, client_length));
if (memcmp(client_protocol, server_protocol, client_length) == 0) {
memcpy_check(conn->application_protocol, client_protocol, client_length);
conn->application_protocol[client_length] = '\0';
return S2N_SUCCESS;
}
}
}
GUARD(s2n_stuffer_reread(&client_protos));
}
return S2N_SUCCESS;
}
/* Old-style extension functions -- remove after extensions refactor is complete */
int s2n_extensions_client_alpn_send(struct s2n_connection *conn, struct s2n_stuffer *out)
{
return s2n_extension_send(&s2n_client_alpn_extension, conn, out);
}
int s2n_recv_client_alpn(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
return s2n_extension_recv(&s2n_client_alpn_extension, conn, extension);
}
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