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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2021 OpenVPN Inc <sales@openvpn.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef OCC_H
#define OCC_H
#include "forward.h"
/* OCC_STRING_SIZE must be set to sizeof (occ_magic) */
#define OCC_STRING_SIZE 16
/*
* OCC (OpenVPN Configuration Control) protocol opcodes.
*/
#define OCC_REQUEST 0 /* request options string from peer */
#define OCC_REPLY 1 /* deliver options string to peer */
/*
* Send an OCC_REQUEST once every OCC_INTERVAL
* seconds until a reply is received.
*
* If we haven't received a reply after
* OCC_N_TRIES, give up.
*/
#define OCC_INTERVAL_SECONDS 10
#define OCC_N_TRIES 12
/*
* Other OCC protocol opcodes used to estimate the MTU empirically.
*/
#define OCC_MTU_LOAD_REQUEST 2 /* Ask peer to send a big packet to us */
#define OCC_MTU_LOAD 3 /* Send a big packet to peer */
#define OCC_MTU_REQUEST 4 /* Ask peer to tell us the largest
* packet it has received from us so far */
#define OCC_MTU_REPLY 5 /* Send largest packet size to peer */
/*
* Process one command from mtu_load_test_sequence
* once every n seconds, if --mtu-test is specified.
*/
#define OCC_MTU_LOAD_INTERVAL_SECONDS 3
/*
* Send an exit message to remote.
*/
#define OCC_EXIT 6
/*
* Used to conduct a load test command sequence
* of UDP connection for empirical MTU measurement.
*/
struct mtu_load_test
{
int op; /* OCC opcode to send to peer */
int delta; /* determine packet size to send by using
* this delta against currently
* configured MTU */
};
extern const uint8_t occ_magic[];
static inline bool
is_occ_msg(const struct buffer *buf)
{
return buf_string_match_head(buf, occ_magic, OCC_STRING_SIZE);
}
void process_received_occ_msg(struct context *c);
void check_send_occ_req_dowork(struct context *c);
void check_send_occ_load_test_dowork(struct context *c);
void check_send_occ_msg_dowork(struct context *c);
/*
* Inline functions
*/
static inline int
occ_reset_op(void)
{
return -1;
}
/*
* Should we send an OCC_REQUEST message?
*/
static inline void
check_send_occ_req(struct context *c)
{
if (event_timeout_defined(&c->c2.occ_interval)
&& event_timeout_trigger(&c->c2.occ_interval,
&c->c2.timeval,
(!TO_LINK_DEF(c) && c->c2.occ_op < 0) ? ETT_DEFAULT : 0))
{
check_send_occ_req_dowork(c);
}
}
/*
* Should we send an MTU load test?
*/
static inline void
check_send_occ_load_test(struct context *c)
{
if (event_timeout_defined(&c->c2.occ_mtu_load_test_interval)
&& event_timeout_trigger(&c->c2.occ_mtu_load_test_interval,
&c->c2.timeval,
(!TO_LINK_DEF(c) && c->c2.occ_op < 0) ? ETT_DEFAULT : 0))
{
check_send_occ_load_test_dowork(c);
}
}
/*
* Should we send an OCC message?
*/
static inline void
check_send_occ_msg(struct context *c)
{
if (c->c2.occ_op >= 0)
{
if (!TO_LINK_DEF(c))
{
check_send_occ_msg_dowork(c);
}
else
{
tv_clear(&c->c2.timeval); /* ZERO-TIMEOUT */
}
}
}
#endif /* ifndef OCC_H */
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