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) 2002-2018 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, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 */
23
24 #ifndef OCC_H
25 #define OCC_H
26
27 #include "forward.h"
28
29 /* OCC_STRING_SIZE must be set to sizeof (occ_magic) */
30 #define OCC_STRING_SIZE 16
31
32 /*
33 * OCC (OpenVPN Configuration Control) protocol opcodes.
34 */
35
36 #define OCC_REQUEST 0 /* request options string from peer */
37 #define OCC_REPLY 1 /* deliver options string to peer */
38
39 /*
40 * Send an OCC_REQUEST once every OCC_INTERVAL
41 * seconds until a reply is received.
42 *
43 * If we haven't received a reply after
44 * OCC_N_TRIES, give up.
45 */
46 #define OCC_INTERVAL_SECONDS 10
47 #define OCC_N_TRIES 12
48
49 /*
50 * Other OCC protocol opcodes used to estimate the MTU empirically.
51 */
52 #define OCC_MTU_LOAD_REQUEST 2 /* Ask peer to send a big packet to us */
53 #define OCC_MTU_LOAD 3 /* Send a big packet to peer */
54 #define OCC_MTU_REQUEST 4 /* Ask peer to tell us the largest
55 * packet it has received from us so far */
56 #define OCC_MTU_REPLY 5 /* Send largest packet size to peer */
57
58 /*
59 * Process one command from mtu_load_test_sequence
60 * once every n seconds, if --mtu-test is specified.
61 */
62 #define OCC_MTU_LOAD_INTERVAL_SECONDS 3
63
64 /*
65 * Send an exit message to remote.
66 */
67 #define OCC_EXIT 6
68
69 /*
70 * Used to conduct a load test command sequence
71 * of UDP connection for empirical MTU measurement.
72 */
73 struct mtu_load_test
74 {
75 int op; /* OCC opcode to send to peer */
76 int delta; /* determine packet size to send by using
77 * this delta against currently
78 * configured MTU */
79 };
80
81 extern const uint8_t occ_magic[];
82
83 static inline bool
is_occ_msg(const struct buffer * buf)84 is_occ_msg(const struct buffer *buf)
85 {
86 return buf_string_match_head(buf, occ_magic, OCC_STRING_SIZE);
87 }
88
89 void process_received_occ_msg(struct context *c);
90
91 void check_send_occ_req_dowork(struct context *c);
92
93 void check_send_occ_load_test_dowork(struct context *c);
94
95 void check_send_occ_msg_dowork(struct context *c);
96
97 /*
98 * Inline functions
99 */
100
101 static inline int
occ_reset_op(void)102 occ_reset_op(void)
103 {
104 return -1;
105 }
106
107 /*
108 * Should we send an OCC_REQUEST message?
109 */
110 static inline void
check_send_occ_req(struct context * c)111 check_send_occ_req(struct context *c)
112 {
113 if (event_timeout_defined(&c->c2.occ_interval)
114 && event_timeout_trigger(&c->c2.occ_interval,
115 &c->c2.timeval,
116 (!TO_LINK_DEF(c) && c->c2.occ_op < 0) ? ETT_DEFAULT : 0))
117 {
118 check_send_occ_req_dowork(c);
119 }
120 }
121
122 /*
123 * Should we send an MTU load test?
124 */
125 static inline void
check_send_occ_load_test(struct context * c)126 check_send_occ_load_test(struct context *c)
127 {
128 if (event_timeout_defined(&c->c2.occ_mtu_load_test_interval)
129 && event_timeout_trigger(&c->c2.occ_mtu_load_test_interval,
130 &c->c2.timeval,
131 (!TO_LINK_DEF(c) && c->c2.occ_op < 0) ? ETT_DEFAULT : 0))
132 {
133 check_send_occ_load_test_dowork(c);
134 }
135 }
136
137 /*
138 * Should we send an OCC message?
139 */
140 static inline void
check_send_occ_msg(struct context * c)141 check_send_occ_msg(struct context *c)
142 {
143 if (c->c2.occ_op >= 0)
144 {
145 if (!TO_LINK_DEF(c))
146 {
147 check_send_occ_msg_dowork(c);
148 }
149 else
150 {
151 tv_clear(&c->c2.timeval); /* ZERO-TIMEOUT */
152 }
153 }
154 }
155
156 #endif /* ifndef OCC_H */
157