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Re-added backtrack handling code.

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git-svn-id: http://svn.openvpn.net/projects/openvpn/branches/BETA21/openvpn@1008 e7ae566f-a301-0410-adde-c780ea21d3b5
This commit is contained in:
james 2006-04-13 20:02:27 +00:00
parent a8105c6747
commit e5239fc26e
3 changed files with 84 additions and 3 deletions
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49
otime.c
View File

@ -36,11 +36,47 @@
time_t now = 0; /* GLOBAL */
#ifdef HAVE_GETTIMEOFDAY
#if TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY)
static time_t now_adj = 0; /* GLOBAL */
time_t now_usec = 0; /* GLOBAL */
#endif
/*
* Try to filter out time instability caused by the system
* clock backtracking or jumping forward.
*/
void
update_now (const time_t system_time)
{
const int forward_threshold = 86400; /* threshold at which to dampen forward jumps */
const int backward_trigger = 10; /* backward jump must be >= this many seconds before we adjust */
time_t real_time = system_time + now_adj;
if (real_time > now)
{
const time_t overshoot = real_time - now - 1;
if (overshoot > forward_threshold && now_adj >= overshoot)
{
now_adj -= overshoot;
real_time -= overshoot;
}
now = real_time;
}
else if (real_time < now - backward_trigger)
now_adj += (now - real_time);
}
void
update_now_usec (struct timeval *tv)
{
const time_t last = now;
update_now (tv->tv_sec);
if (now > last || (now == last && tv->tv_usec > now_usec))
now_usec = tv->tv_usec;
}
#endif /* TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY) */
/*
* Return a numerical string describing a struct timeval.
@ -167,6 +203,11 @@ gettimeofday_calibrate (void)
gtc_last = gtc;
}
/*
* Rewritten by JY for OpenVPN 2.1, after I realized that
* QueryPerformanceCounter takes nearly 2 orders of magnitude
* more processor cycles than GetTickCount.
*/
int
gettimeofday (struct timeval *tv, void *tz)
{
@ -176,6 +217,7 @@ gettimeofday (struct timeval *tv, void *tz)
unsigned int msec;
const int backtrack_hold_seconds = 10;
/* recalibrate at the dreaded 49.7 day mark */
if (!gtc_base || gtc < gtc_last)
gettimeofday_calibrate ();
gtc_last = gtc;
@ -193,6 +235,9 @@ gettimeofday (struct timeval *tv, void *tz)
}
else if (sec < last_sec)
{
/* We try to dampen out backtracks of less than backtrack_hold_seconds.
Larger backtracks will be passed through and dealt with by the
TIME_BACKTRACK_PROTECTION code (if enabled) */
if (sec > last_sec - backtrack_hold_seconds)
{
sec = last_sec;

36
otime.h
View File

@ -58,6 +58,40 @@ extern time_t now; /* updated frequently to time(NULL) */
void time_test (void);
#if TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY)
void update_now (const time_t system_time);
extern time_t now_usec;
void update_now_usec (struct timeval *tv);
static inline int
openvpn_gettimeofday (struct timeval *tv, void *tz)
{
const int status = gettimeofday (tv, tz);
if (!status)
{
update_now_usec (tv);
tv->tv_sec = now;
tv->tv_usec = now_usec;
}
return status;
}
static inline void
update_time (void)
{
#ifdef WIN32
/* on WIN32, gettimeofday is faster than time(NULL) */
struct timeval tv;
openvpn_gettimeofday (&tv, NULL);
#else
update_now (time (NULL));
#endif
}
#else /* !(TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY)) */
static inline void
update_time (void)
{
@ -85,6 +119,8 @@ openvpn_gettimeofday (struct timeval *tv, void *tz)
#endif
#endif /* TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY) */
static inline time_t
openvpn_time (time_t *t)
{

2
syshead.h
View File

@ -498,7 +498,7 @@ socket_defined (const socket_descriptor_t sd)
* Reduce sensitivity to system clock instability
* and backtracks.
*/
//#define TIME_BACKTRACK_PROTECTION 1 // JYFIXME
#define TIME_BACKTRACK_PROTECTION 1
/*
* Is non-blocking connect() supported?