OpenVPN
session_id.c
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1/*
2 * OpenVPN -- An application to securely tunnel IP networks
3 * over a single UDP port, with support for SSL/TLS-based
4 * session authentication and key exchange,
5 * packet encryption, packet authentication, and
6 * packet compression.
7 *
8 * Copyright (C) 2002-2025 OpenVPN Inc <sales@openvpn.net>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2
12 * as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, see <https://www.gnu.org/licenses/>.
21 */
22
23/*
24 * Each session is identified by a random 8-byte session identifier.
25 *
26 * For efficiency, the session id is only transmitted over the control
27 * channel (which only sees traffic occasionally when keys are being
28 * negotiated). The data channel sees a smaller version of the session-id --
29 * it is called the key_id and is currently 2 bits long.
30 */
31
32#ifdef HAVE_CONFIG_H
33#include "config.h"
34#endif
35
36#include "syshead.h"
37
38#include "error.h"
39#include "common.h"
40#include "crypto.h"
41#include "session_id.h"
42
43#include "memdbg.h"
44
46
47void
49{
50 prng_bytes(sid->id, SID_SIZE);
51}
52
53const char *
54session_id_print(const struct session_id *sid, struct gc_arena *gc)
55{
56 return format_hex(sid->id, SID_SIZE, 0, gc);
57}
static char * format_hex(const uint8_t *data, int size, int maxoutput, struct gc_arena *gc)
Definition buffer.h:503
void prng_bytes(uint8_t *output, int len)
Definition crypto.c:1709
Data Channel Cryptography Module.
void session_id_random(struct session_id *sid)
Definition session_id.c:48
const struct session_id x_session_id_zero
Definition session_id.c:45
const char * session_id_print(const struct session_id *sid, struct gc_arena *gc)
Definition session_id.c:54
#define SID_SIZE
Definition session_id.h:44
Garbage collection arena used to keep track of dynamically allocated memory.
Definition buffer.h:116
uint8_t id[8]
Definition session_id.h:39
struct gc_arena gc
Definition test_ssl.c:154