1/*
2 *  OpenVPN -- An application to securely tunnel IP networks
3 *             over a single TCP/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) 2002-2010 OpenVPN Technologies, 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
20 *  along with this program (see the file COPYING included with this
21 *  distribution); if not, write to the Free Software Foundation, Inc.,
22 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
23 */
24
25#ifndef OCC_H
26#define OCC_H
27
28#ifdef ENABLE_OCC
29
30#include "forward.h"
31
32/* OCC_STRING_SIZE must be set to sizeof (occ_magic) */
33#define OCC_STRING_SIZE 16
34
35/*
36 * OCC (OpenVPN Configuration Control) protocol opcodes.
37 */
38
39#define OCC_REQUEST   0		/* request options string from peer */
40#define OCC_REPLY     1		/* deliver options string to peer */
41
42/*
43 * Send an OCC_REQUEST once every OCC_INTERVAL
44 * seconds until a reply is received.
45 *
46 * If we haven't received a reply after
47 * OCC_N_TRIES, give up.
48 */
49#define OCC_INTERVAL_SECONDS 10
50#define OCC_N_TRIES          12
51
52/*
53 * Other OCC protocol opcodes used to estimate the MTU empirically.
54 */
55#define OCC_MTU_LOAD_REQUEST   2	/* Ask peer to send a big packet to us */
56#define OCC_MTU_LOAD           3	/* Send a big packet to peer */
57#define OCC_MTU_REQUEST        4	/* Ask peer to tell us the largest
58					   packet it has received from us so far */
59#define OCC_MTU_REPLY          5	/* Send largest packet size to peer */
60
61/*
62 * Process one command from mtu_load_test_sequence
63 * once every n seconds, if --mtu-test is specified.
64 */
65#define OCC_MTU_LOAD_INTERVAL_SECONDS 3
66
67/*
68 * Send an exit message to remote.
69 */
70#define OCC_EXIT               6
71
72/*
73 * Used to conduct a load test command sequence
74 * of UDP connection for empirical MTU measurement.
75 */
76struct mtu_load_test
77{
78  int op;			/* OCC opcode to send to peer */
79  int delta;			/* determine packet size to send by using
80				   this delta against currently
81				   configured MTU */
82};
83
84extern const uint8_t occ_magic[];
85
86static inline bool
87is_occ_msg (const struct buffer* buf)
88{
89  return buf_string_match_head (buf, occ_magic, OCC_STRING_SIZE);
90}
91
92void process_received_occ_msg (struct context *c);
93
94#endif
95#endif
96