src/openvpn/occ.h

   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) 2002-2005 OpenVPN Solutions LLC <info@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  */
  76 struct 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
  84 extern const uint8_t occ_magic[];
  85
  86 static inline bool
  87 is_occ_msg (const struct buffer* buf)
  88 {
  89   return buf_string_match_head (buf, occ_magic, OCC_STRING_SIZE);
  90 }
  91
  92 void process_received_occ_msg (struct context *c);
  93
  94 #endif
  95 #endif