1 /*
2 * Copyright (C) 2017 Red Hat, Inc.
3 *
4 * Author: Nikos Mavrogiannopoulos
5 *
6 * This file is part of GnuTLS.
7 *
8 * The GnuTLS is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public License
10 * as published by the Free Software Foundation; either version 2.1 of
11 * the License, or (at your option) any later version.
12 *
13 * This library is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public License
19 * along with this program. If not, see <https://www.gnu.org/licenses/>
20 *
21 */
22
23 #ifndef GNUTLS_LIB_EXTV_H
24 #define GNUTLS_LIB_EXTV_H
25
26 #include <gnutls/gnutls.h>
27 #include "str.h"
28
29 /* Iterates through all TLS-type extensions in data, and
30 * calls the callback function for each of them. The ctx, flags
31 * and parse_type are passed verbatim to callback. */
32 int _gnutls_extv_parse(void *ctx,
33 gnutls_ext_raw_process_func cb,
34 const uint8_t * data, int data_size);
35
36 inline static
_gnutls_extv_append_init(gnutls_buffer_st * buf)37 int _gnutls_extv_append_init(gnutls_buffer_st *buf)
38 {
39 unsigned pos;
40 int ret;
41
42 pos = buf->length;
43
44 ret = _gnutls_buffer_append_prefix(buf, 16, 0);
45 if (ret < 0)
46 return gnutls_assert_val(ret);
47
48 return pos;
49 }
50
51 /* its input is the buffer and the return value of _gnutls_extv_append_init()
52 * @is_hello: should be true for client and server hello messages.
53 */
54 inline static
_gnutls_extv_append_final(gnutls_buffer_st * buf,unsigned init,unsigned is_hello)55 int _gnutls_extv_append_final(gnutls_buffer_st *buf, unsigned init, unsigned is_hello)
56 {
57 unsigned size = buf->length - init - 2;
58
59 if (size > UINT16_MAX) /* sent too many extensions */
60 return gnutls_assert_val(GNUTLS_E_HANDSHAKE_TOO_LARGE);
61
62 if (size > 0)
63 _gnutls_write_uint16(size, &buf->data[init]);
64 else if (is_hello && size == 0) {
65 /* there is no point to send empty extension bytes, and
66 * they are known to break certain clients */
67 buf->length -= 2;
68 }
69
70 return 0;
71 }
72
73 typedef int (*extv_append_func)(void *ctx, gnutls_buffer_st *buf);
74
75 int _gnutls_extv_append(gnutls_buffer_st *buf,
76 uint16_t tls_id,
77 void *ctx,
78 extv_append_func cb);
79
80
81 #endif /* GNUTLS_LIB_EXTV_H */
82