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reference.c
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/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Richard P. Curnow 1997-2003
* Copyright (C) Miroslav Lichvar 2009-2018, 2020
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
**********************************************************************
=======================================================================
This module keeps track of the source which we are claiming to be
our reference, for the purposes of generating outgoing NTP packets */
#include "config.h"
#include "sysincl.h"
#include "memory.h"
#include "reference.h"
#include "util.h"
#include "conf.h"
#include "logging.h"
#include "local.h"
#include "sched.h"
/* ================================================== */
/* The minimum allowed skew */
#define MIN_SKEW 1.0e-12
/* The update interval of the reference in the local reference mode */
#define LOCAL_REF_UPDATE_INTERVAL 64.0
/* Interval between updates of the drift file */
#define MAX_DRIFTFILE_AGE 3600.0
static int are_we_synchronised;
static int enable_local_stratum;
static int local_stratum;
static int local_orphan;
static double local_distance;
static struct timespec local_ref_time;
static NTP_Leap our_leap_status;
static int our_leap_sec;
static int our_tai_offset;
static int our_stratum;
static uint32_t our_ref_id;
static IPAddr our_ref_ip;
static struct timespec our_ref_time;
static double our_skew;
static double our_residual_freq;
static double our_root_delay;
static double our_root_dispersion;
static double our_offset_sd;
static double our_frequency_sd;
static double max_update_skew;
static double last_offset;
static double avg2_offset;
static int avg2_moving;
static double correction_time_ratio;
/* Flag indicating that we are initialised */
static int initialised = 0;
/* Current operating mode */
static REF_Mode mode;
/* Threshold and update limit for stepping clock */
static int make_step_limit;
static double make_step_threshold;
/* Number of updates before offset checking, number of ignored updates
before exiting and the maximum allowed offset */
static int max_offset_delay;
static int max_offset_ignore;
static double max_offset;
/* Threshold for logging clock changes to syslog */
static double log_change_threshold;
/* Flag, threshold and user for sending mail notification on large clock changes */
static int do_mail_change;
static double mail_change_threshold;
static char *mail_change_user;
/* Handler for mode ending */
static REF_ModeEndHandler mode_end_handler = NULL;
/* Filename of the drift file. */
static char *drift_file=NULL;
static double drift_file_age;
static void update_drift_file(double, double);
/* Leap second handling mode */
static REF_LeapMode leap_mode;
/* Time of UTC midnight of the upcoming or previous leap second */
static time_t leap_when;
/* Flag indicating the clock was recently corrected for leap second and it may
not have correct time yet (missing 23:59:60 in the UTC time scale) */
static int leap_in_progress;
/* Timer for the leap second handler */
static SCH_TimeoutID leap_timeout_id;
/* Name of a system timezone containing leap seconds occuring at midnight */
static char *leap_tzname;
/* ================================================== */
static LOG_FileID logfileid;
/* ================================================== */
/* Exponential moving averages of absolute clock frequencies
used as a fallback when synchronisation is lost. */
struct fb_drift {
double freq;
double secs;
};
static int fb_drift_min;
static int fb_drift_max;
static struct fb_drift *fb_drifts = NULL;
static int next_fb_drift;
static SCH_TimeoutID fb_drift_timeout_id;
/* Monotonic timestamp of the last reference update */
static double last_ref_update;
static double last_ref_update_interval;
/* ================================================== */
static NTP_Leap get_tz_leap(time_t when, int *tai_offset);
static void update_leap_status(NTP_Leap leap, time_t now, int reset);
/* ================================================== */
static void
handle_slew(struct timespec *raw,
struct timespec *cooked,
double dfreq,
double doffset,
LCL_ChangeType change_type,
void *anything)
{
double delta;
struct timespec now;
if (!UTI_IsZeroTimespec(&our_ref_time))
UTI_AdjustTimespec(&our_ref_time, cooked, &our_ref_time, &delta, dfreq, doffset);
if (change_type == LCL_ChangeUnknownStep) {
last_ref_update = 0.0;
REF_SetUnsynchronised();
}
/* When the clock was stepped, check if that doesn't change our leap status
and also reset the leap timeout to undo the shift in the scheduler */
if (change_type != LCL_ChangeAdjust && our_leap_sec && !leap_in_progress) {
LCL_ReadRawTime(&now);
update_leap_status(our_leap_status, now.tv_sec, 1);
}
}
/* ================================================== */
void
REF_Initialise(void)
{
FILE *in;
double file_freq_ppm, file_skew_ppm;
double our_frequency_ppm;
int tai_offset;
mode = REF_ModeNormal;
are_we_synchronised = 0;
our_leap_status = LEAP_Unsynchronised;
our_leap_sec = 0;
our_tai_offset = 0;
initialised = 1;
our_root_dispersion = 1.0;
our_root_delay = 1.0;
our_frequency_ppm = 0.0;
our_skew = 1.0; /* i.e. rather bad */
our_residual_freq = 0.0;
our_frequency_sd = 0.0;
our_offset_sd = 0.0;
drift_file_age = 0.0;
/* Now see if we can get the drift file opened */
drift_file = CNF_GetDriftFile();
if (drift_file) {
in = UTI_OpenFile(NULL, drift_file, NULL, 'r', 0);
if (in) {
if (fscanf(in, "%lf%lf", &file_freq_ppm, &file_skew_ppm) == 2) {
/* We have read valid data */
our_frequency_ppm = file_freq_ppm;
our_skew = 1.0e-6 * file_skew_ppm;
if (our_skew < MIN_SKEW)
our_skew = MIN_SKEW;
LOG(LOGS_INFO, "Frequency %.3f +/- %.3f ppm read from %s",
file_freq_ppm, file_skew_ppm, drift_file);
LCL_SetAbsoluteFrequency(our_frequency_ppm);
} else {
LOG(LOGS_WARN, "Could not read valid frequency and skew from driftfile %s",
drift_file);
}
fclose(in);
}
}
if (our_frequency_ppm == 0.0) {
our_frequency_ppm = LCL_ReadAbsoluteFrequency();
if (our_frequency_ppm != 0.0) {
LOG(LOGS_INFO, "Initial frequency %.3f ppm", our_frequency_ppm);
}
}
logfileid = CNF_GetLogTracking() ? LOG_FileOpen("tracking",
" Date (UTC) Time IP Address St Freq ppm Skew ppm Offset L Co Offset sd Rem. corr. Root delay Root disp. Max. error")
: -1;
max_update_skew = fabs(CNF_GetMaxUpdateSkew()) * 1.0e-6;
correction_time_ratio = CNF_GetCorrectionTimeRatio();
enable_local_stratum = CNF_AllowLocalReference(&local_stratum, &local_orphan, &local_distance);
UTI_ZeroTimespec(&local_ref_time);
leap_when = 0;
leap_timeout_id = 0;
leap_in_progress = 0;
leap_mode = CNF_GetLeapSecMode();
/* Switch to step mode if the system driver doesn't support leap */
if (leap_mode == REF_LeapModeSystem && !LCL_CanSystemLeap())
leap_mode = REF_LeapModeStep;
leap_tzname = CNF_GetLeapSecTimezone();
if (leap_tzname) {
/* Check that the timezone has good data for Jun 30 2012 and Dec 31 2012 */
if (get_tz_leap(1341014400, &tai_offset) == LEAP_InsertSecond && tai_offset == 34 &&
get_tz_leap(1356912000, &tai_offset) == LEAP_Normal && tai_offset == 35) {
LOG(LOGS_INFO, "Using %s timezone to obtain leap second data", leap_tzname);
} else {
LOG(LOGS_WARN, "Timezone %s failed leap second check, ignoring", leap_tzname);
leap_tzname = NULL;
}
}
CNF_GetMakeStep(&make_step_limit, &make_step_threshold);
CNF_GetMaxChange(&max_offset_delay, &max_offset_ignore, &max_offset);
CNF_GetMailOnChange(&do_mail_change, &mail_change_threshold, &mail_change_user);
log_change_threshold = CNF_GetLogChange();
CNF_GetFallbackDrifts(&fb_drift_min, &fb_drift_max);
if (fb_drift_max >= fb_drift_min && fb_drift_min > 0) {
fb_drifts = MallocArray(struct fb_drift, fb_drift_max - fb_drift_min + 1);
memset(fb_drifts, 0, sizeof (struct fb_drift) * (fb_drift_max - fb_drift_min + 1));
next_fb_drift = 0;
fb_drift_timeout_id = 0;
}
UTI_ZeroTimespec(&our_ref_time);
last_ref_update = 0.0;
last_ref_update_interval = 0.0;
LCL_AddParameterChangeHandler(handle_slew, NULL);
/* Make first entry in tracking log */
REF_SetUnsynchronised();
}
/* ================================================== */
void
REF_Finalise(void)
{
update_leap_status(LEAP_Unsynchronised, 0, 0);
if (drift_file) {
update_drift_file(LCL_ReadAbsoluteFrequency(), our_skew);
}
LCL_RemoveParameterChangeHandler(handle_slew, NULL);
Free(fb_drifts);
initialised = 0;
}
/* ================================================== */
void REF_SetMode(REF_Mode new_mode)
{
mode = new_mode;
}
/* ================================================== */
REF_Mode
REF_GetMode(void)
{
return mode;
}
/* ================================================== */
void
REF_SetModeEndHandler(REF_ModeEndHandler handler)
{
mode_end_handler = handler;
}
/* ================================================== */
REF_LeapMode
REF_GetLeapMode(void)
{
return leap_mode;
}
/* ================================================== */
/* Update the drift coefficients to the file. */
static void
update_drift_file(double freq_ppm, double skew)
{
FILE *out;
/* Create a temporary file with a '.tmp' extension. */
out = UTI_OpenFile(NULL, drift_file, ".tmp", 'w', 0644);
if (!out)
return;
/* Write the frequency and skew parameters in ppm */
fprintf(out, "%20.6f %20.6f\n", freq_ppm, 1.0e6 * skew);
fclose(out);
/* Rename the temporary file to the correct location */
if (!UTI_RenameTempFile(NULL, drift_file, ".tmp", NULL))
;
}
/* ================================================== */
static void
update_fb_drifts(double freq_ppm, double update_interval)
{
int i, secs;
assert(are_we_synchronised);
if (next_fb_drift > 0) {
#if 0
/* Reset drifts that were used when we were unsynchronised */
for (i = 0; i < next_fb_drift - fb_drift_min; i++)
fb_drifts[i].secs = 0.0;
#endif
next_fb_drift = 0;
}
SCH_RemoveTimeout(fb_drift_timeout_id);
fb_drift_timeout_id = 0;
if (update_interval < 1.0 || update_interval > last_ref_update_interval * 4.0)
return;
for (i = 0; i < fb_drift_max - fb_drift_min + 1; i++) {
secs = 1 << (i + fb_drift_min);
if (fb_drifts[i].secs < secs) {
/* Calculate average over 2 * secs interval before switching to
exponential updating */
fb_drifts[i].freq = (fb_drifts[i].freq * fb_drifts[i].secs +
update_interval * 0.5 * freq_ppm) / (update_interval * 0.5 + fb_drifts[i].secs);
fb_drifts[i].secs += update_interval * 0.5;
} else {
/* Update exponential moving average. The smoothing factor for update
interval equal to secs is about 0.63, for half interval about 0.39,
for double interval about 0.86. */
fb_drifts[i].freq += (1 - 1.0 / exp(update_interval / secs)) *
(freq_ppm - fb_drifts[i].freq);
}
DEBUG_LOG("Fallback drift %d updated: %f ppm %f seconds",
i + fb_drift_min, fb_drifts[i].freq, fb_drifts[i].secs);
}
}
/* ================================================== */
static void
fb_drift_timeout(void *arg)
{
assert(next_fb_drift >= fb_drift_min && next_fb_drift <= fb_drift_max);
fb_drift_timeout_id = 0;
DEBUG_LOG("Fallback drift %d active: %f ppm",
next_fb_drift, fb_drifts[next_fb_drift - fb_drift_min].freq);
LCL_SetAbsoluteFrequency(fb_drifts[next_fb_drift - fb_drift_min].freq);
REF_SetUnsynchronised();
}
/* ================================================== */
static void
schedule_fb_drift(void)
{
int i, c, secs;
double unsynchronised, now;
if (fb_drift_timeout_id)
return; /* already scheduled */
now = SCH_GetLastEventMonoTime();
unsynchronised = now - last_ref_update;
for (c = secs = 0, i = fb_drift_min; i <= fb_drift_max; i++) {
secs = 1 << i;
if (fb_drifts[i - fb_drift_min].secs < secs)
continue;
if (unsynchronised < secs && i > next_fb_drift)
break;
c = i;
}
if (c > next_fb_drift) {
LCL_SetAbsoluteFrequency(fb_drifts[c - fb_drift_min].freq);
next_fb_drift = c;
DEBUG_LOG("Fallback drift %d set", c);
}
if (i <= fb_drift_max) {
next_fb_drift = i;
fb_drift_timeout_id = SCH_AddTimeoutByDelay(secs - unsynchronised, fb_drift_timeout, NULL);
DEBUG_LOG("Fallback drift %d scheduled", i);
}
}
/* ================================================== */
static void
end_ref_mode(int result)
{
mode = REF_ModeIgnore;
/* Dispatch the handler */
if (mode_end_handler)
(mode_end_handler)(result);
}
/* ================================================== */
#define BUFLEN 255
#define S_MAX_USER_LEN "128"
static void
maybe_log_offset(double offset, time_t now)
{
double abs_offset;
FILE *p;
char buffer[BUFLEN], host[BUFLEN];
struct tm *tm;
abs_offset = fabs(offset);
if (abs_offset > log_change_threshold) {
LOG(LOGS_WARN, "System clock wrong by %.6f seconds", -offset);
}
if (do_mail_change &&
(abs_offset > mail_change_threshold)) {
snprintf(buffer, sizeof (buffer), "%s -t", MAIL_PROGRAM);
p = popen(buffer, "w");
if (p) {
if (gethostname(host, sizeof(host)) < 0) {
strcpy(host, "<UNKNOWN>");
}
host[sizeof (host) - 1] = '\0';
fprintf(p, "To: %s\n", mail_change_user);
fprintf(p, "Subject: chronyd reports change to system clock on node [%s]\n", host);
fputs("\n", p);
tm = localtime(&now);
if (tm) {
strftime(buffer, sizeof (buffer),
"On %A, %d %B %Y\n with the system clock reading %H:%M:%S (%Z)", tm);
fputs(buffer, p);
}
/* If offset < 0 the local clock is slow, so we are applying a
positive change to it to bring it into line, hence the
negation of 'offset' in the next statement (and earlier) */
fprintf(p,
"\n\nchronyd started to apply an adjustment of %.3f seconds to it,\n"
" which exceeded the reporting threshold of %.3f seconds\n\n",
-offset, mail_change_threshold);
pclose(p);
} else {
LOG(LOGS_ERR, "Could not send mail notification to user %s\n",
mail_change_user);
}
}
}
/* ================================================== */
static int
is_step_limit_reached(double offset, double offset_correction)
{
if (make_step_limit == 0) {
return 0;
} else if (make_step_limit > 0) {
make_step_limit--;
}
return fabs(offset - offset_correction) > make_step_threshold;
}
/* ================================================== */
static int
is_offset_ok(double offset)
{
if (max_offset_delay < 0)
return 1;
if (max_offset_delay > 0) {
max_offset_delay--;
return 1;
}
if (fabs(offset) > max_offset) {
LOG(LOGS_WARN,
"Adjustment of %.3f seconds exceeds the allowed maximum of %.3f seconds (%s) ",
-offset, max_offset, !max_offset_ignore ? "exiting" : "ignored");
if (!max_offset_ignore)
end_ref_mode(0);
else if (max_offset_ignore > 0)
max_offset_ignore--;
return 0;
}
return 1;
}
/* ================================================== */
static int
is_leap_second_day(time_t when)
{
struct tm *stm;
stm = gmtime(&when);
if (!stm)
return 0;
/* Allow leap second only on the last day of June and December */
return (stm->tm_mon == 5 && stm->tm_mday == 30) ||
(stm->tm_mon == 11 && stm->tm_mday == 31);
}
/* ================================================== */
static NTP_Leap
get_tz_leap(time_t when, int *tai_offset)
{
static time_t last_tz_leap_check;
static NTP_Leap tz_leap;
static int tz_tai_offset;
struct tm stm, *tm;
time_t t;
char *tz_env, tz_orig[128];
*tai_offset = tz_tai_offset;
/* Do this check at most twice a day */
when = when / (12 * 3600) * (12 * 3600);
if (last_tz_leap_check == when)
return tz_leap;
last_tz_leap_check = when;
tz_leap = LEAP_Normal;
tz_tai_offset = 0;
tm = gmtime(&when);
if (!tm)
return tz_leap;
stm = *tm;
/* Temporarily switch to the timezone containing leap seconds */
tz_env = getenv("TZ");
if (tz_env) {
if (strlen(tz_env) >= sizeof (tz_orig))
return tz_leap;
strcpy(tz_orig, tz_env);
}
setenv("TZ", leap_tzname, 1);
tzset();
/* Get the TAI-UTC offset, which started at the epoch at 10 seconds */
t = mktime(&stm);
if (t != -1)
tz_tai_offset = t - when + 10;
/* Set the time to 23:59:60 and see how it overflows in mktime() */
stm.tm_sec = 60;
stm.tm_min = 59;
stm.tm_hour = 23;
t = mktime(&stm);
if (tz_env)
setenv("TZ", tz_orig, 1);
else
unsetenv("TZ");
tzset();
if (t == -1)
return tz_leap;
if (stm.tm_sec == 60)
tz_leap = LEAP_InsertSecond;
else if (stm.tm_sec == 1)
tz_leap = LEAP_DeleteSecond;
*tai_offset = tz_tai_offset;
return tz_leap;
}
/* ================================================== */
static void
leap_end_timeout(void *arg)
{
leap_timeout_id = 0;
leap_in_progress = 0;
if (our_tai_offset)
our_tai_offset += our_leap_sec;
our_leap_sec = 0;
if (leap_mode == REF_LeapModeSystem)
LCL_SetSystemLeap(our_leap_sec, our_tai_offset);
if (our_leap_status == LEAP_InsertSecond ||
our_leap_status == LEAP_DeleteSecond)
our_leap_status = LEAP_Normal;
}
/* ================================================== */
static void
leap_start_timeout(void *arg)
{
leap_in_progress = 1;
switch (leap_mode) {
case REF_LeapModeSystem:
DEBUG_LOG("Waiting for system clock leap second correction");
break;
case REF_LeapModeSlew:
LCL_NotifyLeap(our_leap_sec);
LCL_AccumulateOffset(our_leap_sec, 0.0);
LOG(LOGS_WARN, "Adjusting system clock for leap second");
break;
case REF_LeapModeStep:
LCL_NotifyLeap(our_leap_sec);
LCL_ApplyStepOffset(our_leap_sec);
LOG(LOGS_WARN, "System clock was stepped for leap second");
break;
case REF_LeapModeIgnore:
LOG(LOGS_WARN, "Ignoring leap second");
break;
default:
break;
}
/* Wait until the leap second is over with some extra room to be safe */
leap_timeout_id = SCH_AddTimeoutByDelay(2.0, leap_end_timeout, NULL);
}
/* ================================================== */
static void
set_leap_timeout(time_t now)
{
struct timespec when;
/* Stop old timer if there is one */
SCH_RemoveTimeout(leap_timeout_id);
leap_timeout_id = 0;
leap_in_progress = 0;
if (!our_leap_sec)
return;
leap_when = (now / (24 * 3600) + 1) * (24 * 3600);
/* Insert leap second at 0:00:00 UTC, delete at 23:59:59 UTC. If the clock
will be corrected by the system, timeout slightly sooner to be sure it
will happen before the system correction. */
when.tv_sec = leap_when;
when.tv_nsec = 0;
if (our_leap_sec < 0)
when.tv_sec--;
if (leap_mode == REF_LeapModeSystem) {
when.tv_sec--;
when.tv_nsec = 500000000;
}
leap_timeout_id = SCH_AddTimeout(&when, leap_start_timeout, NULL);
}
/* ================================================== */
static void
update_leap_status(NTP_Leap leap, time_t now, int reset)
{
NTP_Leap tz_leap;
int leap_sec, tai_offset;
leap_sec = 0;
tai_offset = 0;
if (leap_tzname && now) {
tz_leap = get_tz_leap(now, &tai_offset);
if (leap == LEAP_Normal)
leap = tz_leap;
}
if (leap == LEAP_InsertSecond || leap == LEAP_DeleteSecond) {
/* Check that leap second is allowed today */
if (is_leap_second_day(now)) {
if (leap == LEAP_InsertSecond) {
leap_sec = 1;
} else {
leap_sec = -1;
}
} else {
leap = LEAP_Normal;
}
}
if ((leap_sec != our_leap_sec || tai_offset != our_tai_offset)
&& !REF_IsLeapSecondClose(NULL, 0.0)) {
our_leap_sec = leap_sec;
our_tai_offset = tai_offset;
switch (leap_mode) {
case REF_LeapModeSystem:
LCL_SetSystemLeap(our_leap_sec, our_tai_offset);
/* Fall through */
case REF_LeapModeSlew:
case REF_LeapModeStep:
case REF_LeapModeIgnore:
set_leap_timeout(now);
break;
default:
assert(0);
break;
}
} else if (reset) {
set_leap_timeout(now);
}
our_leap_status = leap;
}
/* ================================================== */
static double
get_root_dispersion(struct timespec *ts)
{
if (UTI_IsZeroTimespec(&our_ref_time))
return 1.0;
return our_root_dispersion +
fabs(UTI_DiffTimespecsToDouble(ts, &our_ref_time)) *
(our_skew + fabs(our_residual_freq) + LCL_GetMaxClockError());
}
/* ================================================== */
static void
update_sync_status(struct timespec *now)
{
double elapsed;
elapsed = fabs(UTI_DiffTimespecsToDouble(now, &our_ref_time));
LCL_SetSyncStatus(are_we_synchronised,
our_offset_sd + elapsed * our_frequency_sd,
our_root_delay / 2.0 + get_root_dispersion(now));
}
/* ================================================== */
static void
write_log(struct timespec *now, int combined_sources, double freq,
double offset, double offset_sd, double uncorrected_offset,
double orig_root_distance)
{
const char leap_codes[4] = {'N', '+', '-', '?'};
double root_dispersion, max_error;
static double last_sys_offset = 0.0;
if (logfileid == -1)
return;
max_error = orig_root_distance + fabs(last_sys_offset);
root_dispersion = get_root_dispersion(now);
last_sys_offset = offset - uncorrected_offset;
LOG_FileWrite(logfileid,
"%s %-15s %2d %10.3f %10.3f %10.3e %1c %2d %10.3e %10.3e %10.3e %10.3e %10.3e",
UTI_TimeToLogForm(now->tv_sec),
our_ref_ip.family != IPADDR_UNSPEC ?
UTI_IPToString(&our_ref_ip) : UTI_RefidToString(our_ref_id),
our_stratum, freq, 1.0e6 * our_skew, offset,
leap_codes[our_leap_status], combined_sources, offset_sd,
uncorrected_offset, our_root_delay, root_dispersion, max_error);
}
/* ================================================== */
static void
special_mode_sync(int valid, double offset)
{
int step;
switch (mode) {
case REF_ModeInitStepSlew:
if (!valid) {
LOG(LOGS_WARN, "No suitable source for initstepslew");
end_ref_mode(0);
break;
}
step = fabs(offset) >= CNF_GetInitStepThreshold();
LOG(LOGS_INFO, "System's initial offset : %.6f seconds %s of true (%s)",
fabs(offset), offset >= 0 ? "fast" : "slow", step ? "step" : "slew");
if (step)
LCL_ApplyStepOffset(offset);
else
LCL_AccumulateOffset(offset, 0.0);
end_ref_mode(1);
break;
case REF_ModeUpdateOnce:
case REF_ModePrintOnce:
if (!valid) {
LOG(LOGS_WARN, "No suitable source for synchronisation");
end_ref_mode(0);
break;
}
step = mode == REF_ModeUpdateOnce;
LOG(LOGS_INFO, "System clock wrong by %.6f seconds (%s)",
-offset, step ? "step" : "ignored");
if (step)
LCL_ApplyStepOffset(offset);
end_ref_mode(1);
break;
case REF_ModeIgnore:
/* Do nothing until the mode is changed */
break;
default:
assert(0);
}
}
/* ================================================== */
static void
get_clock_estimates(int manual,
double measured_freq, double measured_skew,
double *estimated_freq, double *estimated_skew,
double *residual_freq)
{
double gain, expected_freq, expected_skew, extra_skew;
/* We assume that the local clock is running according to our previously
determined value */
expected_freq = 0.0;
expected_skew = our_skew;
/* Set new frequency based on weighted average of the expected and measured
skew. Disable updates that are based on totally unreliable frequency
information unless it is a manual reference. */
if (manual) {
gain = 1.0;
} else if (fabs(measured_skew) > max_update_skew) {
DEBUG_LOG("Skew %f too large to track", measured_skew);
gain = 0.0;
} else {
gain = 3.0 * SQUARE(expected_skew) /
(3.0 * SQUARE(expected_skew) + SQUARE(measured_skew));
}
gain = CLAMP(0.0, gain, 1.0);
*estimated_freq = expected_freq + gain * (measured_freq - expected_freq);
*residual_freq = measured_freq - *estimated_freq;
extra_skew = sqrt(SQUARE(expected_freq - *estimated_freq) * (1.0 - gain) +
SQUARE(measured_freq - *estimated_freq) * gain);
*estimated_skew = expected_skew + gain * (measured_skew - expected_skew) + extra_skew;
}
/* ================================================== */
static void
fuzz_ref_time(struct timespec *ts)
{
uint32_t rnd;
/* Add a random value from interval [-1.0, 0.0] */
UTI_GetRandomBytes(&rnd, sizeof (rnd));
UTI_AddDoubleToTimespec(ts, -(double)rnd / (uint32_t)-1, ts);
}
/* ================================================== */
void
REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
uint32_t ref_id, IPAddr *ref_ip, struct timespec *ref_time,
double offset, double offset_sd,
double frequency, double frequency_sd, double skew,
double root_delay, double root_dispersion)
{
double uncorrected_offset, accumulate_offset, step_offset;
double residual_frequency, local_abs_frequency;
double elapsed, mono_now, update_interval, correction_rate, orig_root_distance;
struct timespec now, raw_now;
int manual;
assert(initialised);
/* Special modes are implemented elsewhere */
if (mode != REF_ModeNormal) {
special_mode_sync(1, offset);
return;
}
manual = leap == LEAP_Unsynchronised;
mono_now = SCH_GetLastEventMonoTime();
LCL_ReadRawTime(&raw_now);
LCL_GetOffsetCorrection(&raw_now, &uncorrected_offset, NULL);
UTI_AddDoubleToTimespec(&raw_now, uncorrected_offset, &now);
elapsed = UTI_DiffTimespecsToDouble(&now, ref_time);
offset += elapsed * frequency;
if (last_ref_update != 0.0) {
update_interval = mono_now - last_ref_update;
} else {
update_interval = 0.0;
}
/* Get new estimates of the frequency and skew including the new data */