src/openvpn/interval.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 /*
  26  * The interval_ routines are designed to optimize the calling of a routine
  27  * (normally tls_multi_process()) which can be called less frequently
  28  * between triggers.
  29  */
  30
  31 #ifndef INTERVAL_H
  32 #define INTERVAL_H
  33
  34 #include "otime.h"
  35
  36 #define INTERVAL_DEBUG 0
  37
  38 /*
  39  * Designed to limit calls to expensive functions that need to be called
  40  * regularly.
  41  */
  42
  43 struct interval
  44 {
  45   interval_t refresh;
  46   interval_t horizon;
  47   time_t future_trigger;
  48   time_t last_action;
  49   time_t last_test_true;
  50 };
  51
  52 void interval_init (struct interval *top, int horizon, int refresh);
  53
  54 /*
  55  * IF
  56  *   last_action less than horizon seconds ago
  57  *   OR last_test_true more than refresh seconds ago
  58  *   OR hit future_trigger
  59  * THEN
  60  *   return true
  61  * ELSE
  62  *   set wakeup to the number of seconds until a true return
  63  *   return false
  64  */
  65
  66 static inline bool
  67 interval_test (struct interval* top)
  68 {
  69   bool trigger = false;
  70   const time_t local_now = now;
  71
  72   if (top->future_trigger && local_now >= top->future_trigger)
  73     {
  74       trigger = true;
  75       top->future_trigger = 0;
  76     }
  77
  78   if (top->last_action + top->horizon > local_now ||
  79       top->last_test_true + top->refresh <= local_now ||
  80       trigger)
  81     {
  82       top->last_test_true = local_now;
  83 #if INTERVAL_DEBUG
  84       dmsg (D_INTERVAL, "INTERVAL interval_test true");
  85 #endif
  86       return true;
  87     }
  88   else
  89     {
  90       return false;
  91     }
  92 }
  93
  94 static inline void
  95 interval_schedule_wakeup (struct interval* top, interval_t *wakeup)
  96 {
  97   const time_t local_now = now;
  98   interval_earliest_wakeup (wakeup, top->last_test_true + top->refresh, local_now);
  99   interval_earliest_wakeup (wakeup, top->future_trigger, local_now);
 100 #if INTERVAL_DEBUG
 101   dmsg (D_INTERVAL, "INTERVAL interval_schedule wakeup=%d", (int)*wakeup);
 102 #endif
 103 }
 104
 105 /*
 106  * In wakeup seconds, interval_test will return true once.
 107  */
 108 static inline void
 109 interval_future_trigger (struct interval* top, interval_t wakeup) {
 110   if (wakeup)
 111     {
 112 #if INTERVAL_DEBUG
 113       dmsg (D_INTERVAL, "INTERVAL interval_future_trigger %d", (int)wakeup);
 114 #endif
 115       top->future_trigger = now + wakeup;
 116     }
 117 }
 118
 119 /*
 120  * Once an action is triggered, interval_test will remain true for
 121  * horizon seconds.
 122  */
 123 static inline void
 124 interval_action (struct interval* top)
 125 {
 126 #if INTERVAL_DEBUG
 127   dmsg (D_INTERVAL, "INTERVAL action");
 128 #endif
 129   top->last_action = now;
 130 }
 131
 132 /*
 133  * Measure when n seconds beyond an event have elapsed
 134  */
 135
 136 struct event_timeout
 137 {
 138   bool defined;
 139   interval_t n;
 140   time_t last; /* time of last event */
 141 };
 142
 143 static inline bool
 144 event_timeout_defined (const struct event_timeout* et)
 145 {
 146   return et->defined;
 147 }
 148
 149 static inline void
 150 event_timeout_clear (struct event_timeout* et)
 151 {
 152   et->defined = false;
 153   et->n = 0;
 154   et->last = 0;
 155 }
 156
 157 static inline struct event_timeout
 158 event_timeout_clear_ret ()
 159 {
 160   struct event_timeout ret;
 161   event_timeout_clear (&ret);
 162   return ret;
 163 }
 164
 165 static inline void
 166 event_timeout_init (struct event_timeout* et, interval_t n, const time_t local_now)
 167 {
 168   et->defined = true;
 169   et->n = (n >= 0) ? n : 0;
 170   et->last = local_now;
 171 }
 172
 173 static inline void
 174 event_timeout_reset (struct event_timeout* et)
 175 {
 176   if (et->defined)
 177     et->last = now;
 178 }
 179
 180 /*
 181  * This is the principal function for testing and triggering recurring
 182  * timers and will return true on a timer signal event.
 183  * If et_const_retry == ETT_DEFAULT and a signal occurs,
 184  * the function will return true and *et will be armed for the
 185  * next event.  If et_const_retry >= 0 and a signal occurs,
 186  * *et will not be touched, but *tv will be set to
 187  * minimum (*tv, et_const_retry) for a future re-test,
 188  * and the function will return true.
 189  */
 190
 191 #define ETT_DEFAULT (-1)
 192
 193 bool event_timeout_trigger (struct event_timeout *et,
 194                             struct timeval *tv,
 195                             const int et_const_retry);
 196
 197 /*
 198  * Measure time intervals in microseconds
 199  */
 200
 201 #define USEC_TIMER_MAX      60 /* maximum interval size in seconds */
 202
 203 #define USEC_TIMER_MAX_USEC (USEC_TIMER_MAX * 1000000)
 204
 205 struct usec_timer {
 206   struct timeval start;
 207   struct timeval end;
 208 };
 209
 210 #ifdef HAVE_GETTIMEOFDAY
 211
 212 static inline void
 213 usec_timer_start (struct usec_timer *obj)
 214 {
 215   CLEAR (*obj);
 216   gettimeofday (&obj->start, NULL);
 217 }
 218
 219 static inline void
 220 usec_timer_end (struct usec_timer *obj)
 221 {
 222   gettimeofday (&obj->end, NULL);
 223 }
 224
 225 #endif /* HAVE_GETTIMEOFDAY */
 226
 227 static inline bool
 228 usec_timer_interval_defined (struct usec_timer *obj)
 229 {
 230   return obj->start.tv_sec && obj->end.tv_sec;
 231 }
 232
 233 static inline int
 234 usec_timer_interval (struct usec_timer *obj)
 235 {
 236   return tv_subtract (&obj->end, &obj->start, USEC_TIMER_MAX);
 237 }
 238
 239 #endif /* INTERVAL_H */