1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
/*
* 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_max_frag_len.h"
#include <stdint.h>
#include <sys/param.h>
#include "tls/s2n_tls.h"
#include "tls/s2n_tls_parameters.h"
#include "utils/s2n_safety.h"
static bool s2n_client_max_frag_len_should_send(struct s2n_connection *conn);
static int s2n_client_max_frag_len_send(struct s2n_connection *conn, struct s2n_stuffer *out);
static int s2n_client_max_frag_len_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
const s2n_extension_type s2n_client_max_frag_len_extension = {
.iana_value = TLS_EXTENSION_MAX_FRAG_LEN,
.is_response = false,
.send = s2n_client_max_frag_len_send,
.recv = s2n_client_max_frag_len_recv,
.should_send = s2n_client_max_frag_len_should_send,
.if_missing = s2n_extension_noop_if_missing,
};
static bool s2n_client_max_frag_len_should_send(struct s2n_connection *conn)
{
return conn->config->mfl_code != S2N_TLS_MAX_FRAG_LEN_EXT_NONE;
}
static int s2n_client_max_frag_len_send(struct s2n_connection *conn, struct s2n_stuffer *out)
{
return s2n_stuffer_write_uint8(out, conn->config->mfl_code);
}
static int s2n_client_max_frag_len_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
if (!conn->config->accept_mfl) {
return S2N_SUCCESS;
}
uint8_t mfl_code;
POSIX_GUARD(s2n_stuffer_read_uint8(extension, &mfl_code));
/*
*= https://tools.ietf.org/rfc/rfc6066#section-4
*= type=exception
*= reason=For compatibility, we choose to ignore malformed extensions if they are optional
*# If a server receives a maximum fragment length negotiation request
*# for a value other than the allowed values, it MUST abort the
*# handshake with an "illegal_parameter" alert.
*/
if (mfl_code >= s2n_array_len(mfl_code_to_length) || mfl_code_to_length[mfl_code] > S2N_TLS_MAXIMUM_FRAGMENT_LENGTH) {
return S2N_SUCCESS;
}
/*
*= https://tools.ietf.org/rfc/rfc6066#section-4
*# Once a maximum fragment length other than 2^14 has been successfully
*# negotiated, the client and server MUST immediately begin fragmenting
*# messages (including handshake messages) to ensure that no fragment
*# larger than the negotiated length is sent.
*/
conn->negotiated_mfl_code = mfl_code;
POSIX_GUARD_RESULT(s2n_connection_set_max_fragment_length(conn, mfl_code_to_length[mfl_code]));
return S2N_SUCCESS;
}
|
