src/openvpn/ping.c

   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 #ifdef WIN32
  26 #include "config-win32.h"
  27 #else
  28 #include "config.h"
  29 #endif
  30
  31 #include "syshead.h"
  32
  33 #include "ping.h"
  34
  35 #include "memdbg.h"
  36
  37 #include "ping-inline.h"
  38
  39 /*
  40  * This random string identifies an OpenVPN ping packet.
  41  * It should be of sufficient length and randomness
  42  * so as not to collide with other tunnel data.
  43  *
  44  * PING_STRING_SIZE must be sizeof (ping_string)
  45  */
  46 const uint8_t ping_string[] = {
  47   0x2a, 0x18, 0x7b, 0xf3, 0x64, 0x1e, 0xb4, 0xcb,
  48   0x07, 0xed, 0x2d, 0x0a, 0x98, 0x1f, 0xc7, 0x48
  49 };
  50
  51 /*
  52  * Should we exit or restart due to ping (or other authenticated packet)
  53  * not received in n seconds?
  54  */
  55 void
  56 check_ping_restart_dowork (struct context *c)
  57 {
  58   struct gc_arena gc = gc_new ();
  59   switch (c->options.ping_rec_timeout_action)
  60     {
  61     case PING_EXIT:
  62       msg (M_INFO, "%sInactivity timeout (--ping-exit), exiting",
  63            format_common_name (c, &gc));
  64       c->sig->signal_received = SIGTERM;
  65       c->sig->signal_text = "ping-exit";
  66       break;
  67     case PING_RESTART:
  68       msg (M_INFO, "%sInactivity timeout (--ping-restart), restarting",
  69            format_common_name (c, &gc));
  70       c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- Ping Restart */
  71       c->sig->signal_text = "ping-restart";
  72       break;
  73     default:
  74       ASSERT (0);
  75     }
  76   gc_free (&gc);
  77 }
  78
  79 /*
  80  * Should we ping the remote?
  81  */
  82 void
  83 check_ping_send_dowork (struct context *c)
  84 {
  85   c->c2.buf = c->c2.buffers->aux_buf;
  86   ASSERT (buf_init (&c->c2.buf, FRAME_HEADROOM (&c->c2.frame)));
  87   ASSERT (buf_safe (&c->c2.buf, MAX_RW_SIZE_TUN (&c->c2.frame)));
  88   ASSERT (buf_write (&c->c2.buf, ping_string, sizeof (ping_string)));
  89
  90   /*
  91    * We will treat the ping like any other outgoing packet,
  92    * encrypt, sign, etc.
  93    */
  94   encrypt_sign (c, true);
  95   dmsg (D_PACKET_CONTENT, "SENT PING");
  96 }