OpenVPN
interval.h
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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) 2002-2017 OpenVPN Technologies, Inc. <sales@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 along
20  * with this program; if not, write to the Free Software Foundation, Inc.,
21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22  */
23 
24 /*
25  * The interval_ routines are designed to optimize the calling of a routine
26  * (normally tls_multi_process()) which can be called less frequently
27  * between triggers.
28  */
29 
30 #ifndef INTERVAL_H
31 #define INTERVAL_H
32 
33 #include "otime.h"
34 
35 #define INTERVAL_DEBUG 0
36 
37 /*
38  * Designed to limit calls to expensive functions that need to be called
39  * regularly.
40  */
41 
42 struct interval
43 {
47  time_t last_action;
49 };
50 
51 void interval_init(struct interval *top, int horizon, int refresh);
52 
53 /*
54  * IF
55  * last_action less than horizon seconds ago
56  * OR last_test_true more than refresh seconds ago
57  * OR hit future_trigger
58  * THEN
59  * return true
60  * ELSE
61  * set wakeup to the number of seconds until a true return
62  * return false
63  */
64 
65 static inline bool
66 interval_test(struct interval *top)
67 {
68  bool trigger = false;
69  const time_t local_now = now;
70 
71  if (top->future_trigger && local_now >= top->future_trigger)
72  {
73  trigger = true;
74  top->future_trigger = 0;
75  }
76 
77  if (top->last_action + top->horizon > local_now
78  || top->last_test_true + top->refresh <= local_now
79  || trigger)
80  {
81  top->last_test_true = local_now;
82 #if INTERVAL_DEBUG
83  dmsg(D_INTERVAL, "INTERVAL interval_test true");
84 #endif
85  return true;
86  }
87  else
88  {
89  return false;
90  }
91 }
92 
93 static inline void
95 {
96  const time_t local_now = now;
97  interval_earliest_wakeup(wakeup, top->last_test_true + top->refresh, local_now);
98  interval_earliest_wakeup(wakeup, top->future_trigger, local_now);
99 #if INTERVAL_DEBUG
100  dmsg(D_INTERVAL, "INTERVAL interval_schedule wakeup=%d", (int)*wakeup);
101 #endif
102 }
103 
104 /*
105  * In wakeup seconds, interval_test will return true once.
106  */
107 static inline void
109 {
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
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 
137 {
138  bool defined;
140  time_t last; /* time of last event */
141 };
142 
143 static inline bool
145 {
146  return et->defined;
147 }
148 
149 static inline void
151 {
152  et->defined = false;
153  et->n = 0;
154  et->last = 0;
155 }
156 
157 static inline struct event_timeout
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
175 {
176  if (et->defined)
177  {
178  et->last = now;
179  }
180 }
181 
182 static inline void
184 {
185  /* note that you might need to call reset_coarse_timers after this */
186  if (et->defined)
187  {
188  et->n = (n >= 0) ? n : 0;
189  }
190 }
191 
192 /*
193  * Will return the time left for a timeout, this function does not check
194  * if the timeout is actually valid
195  */
196 static inline interval_t
198 {
199  return (int) et->last + et->n - now;
200 }
201 
202 /*
203  * This is the principal function for testing and triggering recurring
204  * timers and will return true on a timer signal event.
205  * If et_const_retry == ETT_DEFAULT and a signal occurs,
206  * the function will return true and *et will be armed for the
207  * next event. If et_const_retry >= 0 and a signal occurs,
208  * *et will not be touched, but *tv will be set to
209  * minimum (*tv, et_const_retry) for a future re-test,
210  * and the function will return true.
211  */
212 
213 #define ETT_DEFAULT (-1)
214 
215 bool event_timeout_trigger(struct event_timeout *et,
216  struct timeval *tv,
217  const int et_const_retry);
218 
219 /*
220  * Measure time intervals in microseconds
221  */
222 
223 #define USEC_TIMER_MAX 60 /* maximum interval size in seconds */
224 
225 #define USEC_TIMER_MAX_USEC (USEC_TIMER_MAX * 1000000)
226 
227 struct usec_timer {
228  struct timeval start;
229  struct timeval end;
230 };
231 
232 #ifdef HAVE_GETTIMEOFDAY
233 
234 static inline void
236 {
237  CLEAR(*obj);
238  openvpn_gettimeofday(&obj->start, NULL);
239 }
240 
241 static inline void
243 {
244  openvpn_gettimeofday(&obj->end, NULL);
245 }
246 
247 #endif /* HAVE_GETTIMEOFDAY */
248 
249 static inline bool
251 {
252  return obj->start.tv_sec && obj->end.tv_sec;
253 }
254 
255 static inline int
257 {
258  return tv_subtract(&obj->end, &obj->start, USEC_TIMER_MAX);
259 }
260 
261 #endif /* INTERVAL_H */
#define USEC_TIMER_MAX
Definition: interval.h:223
struct timeval start
Definition: interval.h:228
static bool usec_timer_interval_defined(struct usec_timer *obj)
Definition: interval.h:250
static void event_timeout_clear(struct event_timeout *et)
Definition: interval.h:150
#define CLEAR(x)
Definition: basic.h:33
static int tv_subtract(const struct timeval *tv1, const struct timeval *tv2, const unsigned int max_seconds)
Definition: otime.h:148
time_t last_action
Definition: interval.h:47
static void interval_future_trigger(struct interval *top, interval_t wakeup)
Definition: interval.h:108
time_t future_trigger
Definition: interval.h:46
static struct event_timeout event_timeout_clear_ret(void)
Definition: interval.h:158
bool event_timeout_trigger(struct event_timeout *et, struct timeval *tv, const int et_const_retry)
Definition: interval.c:45
static void interval_earliest_wakeup(interval_t *wakeup, time_t at, time_t current)
Definition: otime.h:291
static bool interval_test(struct interval *top)
Definition: interval.h:66
struct timeval end
Definition: interval.h:229
#define D_INTERVAL
Definition: errlevel.h:153
static void event_timeout_reset(struct event_timeout *et)
Definition: interval.h:174
static void usec_timer_start(struct usec_timer *obj)
Definition: interval.h:235
time_t now
Definition: otime.c:36
static void interval_action(struct interval *top)
Definition: interval.h:124
static bool event_timeout_defined(const struct event_timeout *et)
Definition: interval.h:144
interval_t refresh
Definition: interval.h:44
interval_t n
Definition: interval.h:139
#define dmsg
Definition: error.h:174
static int openvpn_gettimeofday(struct timeval *tv, void *tz)
Definition: otime.h:115
static void event_timeout_modify_wakeup(struct event_timeout *et, interval_t n)
Definition: interval.h:183
static void interval_schedule_wakeup(struct interval *top, interval_t *wakeup)
Definition: interval.h:94
bool defined
Definition: interval.h:138
time_t last
Definition: interval.h:140
int interval_t
Definition: common.h:45
static int usec_timer_interval(struct usec_timer *obj)
Definition: interval.h:256
void interval_init(struct interval *top, int horizon, int refresh)
Definition: interval.c:37
static void usec_timer_end(struct usec_timer *obj)
Definition: interval.h:242
interval_t horizon
Definition: interval.h:45
static interval_t event_timeout_remaining(struct event_timeout *et)
Definition: interval.h:197
time_t last_test_true
Definition: interval.h:48
static void event_timeout_init(struct event_timeout *et, interval_t n, const time_t local_now)
Definition: interval.h:166