/*
  *  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) 2002-2010 OpenVPN Technologies, 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 (see the file COPYING included with this
  *  distribution); if not, write to the Free Software Foundation, Inc.,
  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
 #ifndef OCC_H
 #define OCC_H
 
 #ifdef ENABLE_OCC
 
 #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);
 
 #endif
 #endif