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Diffstat (limited to '')
| -rw-r--r-- | reference.c | 1437 |
1 files changed, 1437 insertions, 0 deletions
diff --git a/reference.c b/reference.c new file mode 100644 index 0000000..e6cc547 --- /dev/null +++ b/reference.c @@ -0,0 +1,1437 @@ +/* + chronyd/chronyc - Programs for keeping computer clocks accurate. + + ********************************************************************** + * Copyright (C) Richard P. Curnow 1997-2003 + * Copyright (C) Miroslav Lichvar 2009-2018, 2020, 2022 + * + * 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 double last_ref_adjustment; +static int ref_adjustments; + +/* ================================================== */ + +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; + last_ref_adjustment = 0.0; + ref_adjustments = 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); +} + +/* ================================================== */ + +static double +get_correction_rate(double offset_sd, double update_interval) +{ + /* We want to correct the offset quickly, but we also want to keep the + frequency error caused by the correction itself low. + + Define correction rate as the area of the region bounded by the graph of + offset corrected in time. Set the rate so that the time needed to correct + an offset equal to the current sourcestats stddev will be equal to the + update interval multiplied by the correction time ratio (assuming linear + adjustment). The offset and the time needed to make the correction are + inversely proportional. + + This is only a suggestion and it's up to the system driver how the + adjustment will be executed. */ + + return correction_time_ratio * 0.5 * offset_sd * update_interval; +} + +/* ================================================== */ + +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, 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 */ + get_clock_estimates(manual, frequency, skew, + &frequency, &skew, &residual_frequency); + + if (!is_offset_ok(offset)) + return; + + orig_root_distance = our_root_delay / 2.0 + get_root_dispersion(&now); + + are_we_synchronised = leap != LEAP_Unsynchronised; + our_stratum = stratum + 1; + our_ref_id = ref_id; + if (ref_ip) + our_ref_ip = *ref_ip; + else + our_ref_ip.family = IPADDR_UNSPEC; + our_ref_time = *ref_time; + our_skew = skew; + our_residual_freq = residual_frequency; + our_root_delay = root_delay; + our_root_dispersion = root_dispersion; + our_frequency_sd = frequency_sd; + our_offset_sd = offset_sd; + last_ref_update = mono_now; + last_ref_update_interval = update_interval; + last_offset = offset; + + /* Check if the clock should be stepped */ + if (is_step_limit_reached(offset, uncorrected_offset)) { + /* Cancel the uncorrected offset and correct the total offset by step */ + accumulate_offset = uncorrected_offset; + step_offset = offset - uncorrected_offset; + } else { + accumulate_offset = offset; + step_offset = 0.0; + } + + /* Adjust the clock */ + LCL_AccumulateFrequencyAndOffset(frequency, accumulate_offset, + get_correction_rate(offset_sd, update_interval)); + + maybe_log_offset(offset, raw_now.tv_sec); + + if (step_offset != 0.0) { + if (LCL_ApplyStepOffset(step_offset)) + LOG(LOGS_WARN, "System clock was stepped by %.6f seconds", -step_offset); + } + + update_leap_status(leap, raw_now.tv_sec, 0); + update_sync_status(&now); + + /* Add a random error of up to one second to the reference time to make it + less useful when disclosed to NTP and cmdmon clients for estimating + receive timestamps in the interleaved symmetric NTP mode */ + fuzz_ref_time(&our_ref_time); + + local_abs_frequency = LCL_ReadAbsoluteFrequency(); + + write_log(&now, combined_sources, local_abs_frequency, + offset, offset_sd, uncorrected_offset, orig_root_distance); + + if (drift_file) { + /* Update drift file at most once per hour */ + drift_file_age += update_interval; + if (drift_file_age >= MAX_DRIFTFILE_AGE) { + update_drift_file(local_abs_frequency, our_skew); + drift_file_age = 0.0; + } + } + + /* Update fallback drifts */ + if (fb_drifts && are_we_synchronised) { + update_fb_drifts(local_abs_frequency, update_interval); + schedule_fb_drift(); + } + + /* Update the moving average of squares of offset, quickly on start */ + if (avg2_moving) { + avg2_offset += 0.1 * (SQUARE(offset) - avg2_offset); + } else { + if (avg2_offset > 0.0 && avg2_offset < SQUARE(offset)) + avg2_moving = 1; + avg2_offset = SQUARE(offset); + } + + ref_adjustments = 0; +} + +/* ================================================== */ + +int +REF_AdjustReference(double offset, double frequency) +{ + double adj_corr_rate, ref_corr_rate, mono_now; + + mono_now = SCH_GetLastEventMonoTime(); + ref_adjustments++; + + adj_corr_rate = get_correction_rate(fabs(offset), mono_now - last_ref_adjustment); + ref_corr_rate = get_correction_rate(our_offset_sd, last_ref_update_interval) / + ref_adjustments; + last_ref_adjustment = mono_now; + + return LCL_AccumulateFrequencyAndOffsetNoHandlers(frequency, offset, + MAX(adj_corr_rate, ref_corr_rate)); +} + +/* ================================================== */ + +void +REF_SetManualReference +( + struct timespec *ref_time, + double offset, + double frequency, + double skew +) +{ + /* We are not synchronised to an external source, as such. This is + only supposed to be used with the local source option, really. + Log as MANU in the tracking log, packets will have NTP_REFID_LOCAL. */ + REF_SetReference(0, LEAP_Unsynchronised, 1, 0x4D414E55UL, NULL, + ref_time, offset, 0.0, frequency, skew, skew, 0.0, 0.0); +} + +/* ================================================== */ + +void +REF_SetUnsynchronised(void) +{ + /* Variables required for logging to statistics log */ + struct timespec now, now_raw; + double uncorrected_offset; + + assert(initialised); + + /* Special modes are implemented elsewhere */ + if (mode != REF_ModeNormal) { + special_mode_sync(0, 0.0); + return; + } + + LCL_ReadRawTime(&now_raw); + LCL_GetOffsetCorrection(&now_raw, &uncorrected_offset, NULL); + UTI_AddDoubleToTimespec(&now_raw, uncorrected_offset, &now); + + if (fb_drifts) { + schedule_fb_drift(); + } + + update_leap_status(LEAP_Unsynchronised, 0, 0); + our_ref_ip.family = IPADDR_INET4; + our_ref_ip.addr.in4 = 0; + our_stratum = 0; + are_we_synchronised = 0; + + LCL_SetSyncStatus(0, 0.0, 0.0); + + write_log(&now, 0, LCL_ReadAbsoluteFrequency(), 0.0, 0.0, uncorrected_offset, + our_root_delay / 2.0 + get_root_dispersion(&now)); +} + +/* ================================================== */ + +void +REF_UpdateLeapStatus(NTP_Leap leap) +{ + struct timespec raw_now, now; + + /* Wait for a full reference update if not already synchronised */ + if (!are_we_synchronised) + return; + + SCH_GetLastEventTime(&now, NULL, &raw_now); + + update_leap_status(leap, raw_now.tv_sec, 0); + + /* Update also the synchronisation status */ + update_sync_status(&now); +} + +/* ================================================== */ + +void +REF_GetReferenceParams +( + struct timespec *local_time, + int *is_synchronised, + NTP_Leap *leap_status, + int *stratum, + uint32_t *ref_id, + struct timespec *ref_time, + double *root_delay, + double *root_dispersion +) +{ + double dispersion, delta; + + assert(initialised); + + if (are_we_synchronised) { + dispersion = get_root_dispersion(local_time); + } else { + dispersion = 0.0; + } + + /* Local reference is active when enabled and the clock is not synchronised + or the root distance exceeds the threshold */ + + if (are_we_synchronised && + !(enable_local_stratum && our_root_delay / 2 + dispersion > local_distance)) { + + *is_synchronised = 1; + + *stratum = our_stratum; + + *leap_status = !leap_in_progress ? our_leap_status : LEAP_Unsynchronised; + *ref_id = our_ref_id; + *ref_time = our_ref_time; + *root_delay = our_root_delay; + *root_dispersion = dispersion; + + } else if (enable_local_stratum) { + + *is_synchronised = 0; + + *stratum = local_stratum; + *ref_id = NTP_REFID_LOCAL; + + /* Keep the reference timestamp up to date. Adjust the timestamp to make + sure that the transmit timestamp cannot come before this (which might + fail a test of an NTP client). */ + delta = UTI_DiffTimespecsToDouble(local_time, &local_ref_time); + if (delta > LOCAL_REF_UPDATE_INTERVAL || delta < 1.0) { + UTI_AddDoubleToTimespec(local_time, -1.0, &local_ref_time); + fuzz_ref_time(&local_ref_time); + } + + *ref_time = local_ref_time; + + /* Not much else we can do for leap second bits - maybe need to + have a way for the administrator to feed leap bits in */ + *leap_status = LEAP_Normal; + + *root_delay = 0.0; + *root_dispersion = 0.0; + + } else { + + *is_synchronised = 0; + + *leap_status = LEAP_Unsynchronised; + *stratum = NTP_MAX_STRATUM; + *ref_id = NTP_REFID_UNSYNC; + UTI_ZeroTimespec(ref_time); + /* These values seem to be standard for a client, and + any peer or client of ours will ignore them anyway because + we don't claim to be synchronised */ + *root_dispersion = 1.0; + *root_delay = 1.0; + + } +} + +/* ================================================== */ + +int +REF_GetOurStratum(void) +{ + struct timespec now_cooked, ref_time; + int synchronised, stratum; + NTP_Leap leap_status; + uint32_t ref_id; + double root_delay, root_dispersion; + + SCH_GetLastEventTime(&now_cooked, NULL, NULL); + REF_GetReferenceParams(&now_cooked, &synchronised, &leap_status, &stratum, + &ref_id, &ref_time, &root_delay, &root_dispersion); + + return stratum; +} + +/* ================================================== */ + +int +REF_GetOrphanStratum(void) +{ + if (!enable_local_stratum || !local_orphan || mode != REF_ModeNormal) + return NTP_MAX_STRATUM; + return local_stratum; +} + +/* ================================================== */ + +double +REF_GetSkew(void) +{ + return our_skew; +} + +/* ================================================== */ + +void +REF_ModifyMaxupdateskew(double new_max_update_skew) +{ + max_update_skew = new_max_update_skew * 1.0e-6; +} + +/* ================================================== */ + +void +REF_ModifyMakestep(int limit, double threshold) +{ + make_step_limit = limit; + make_step_threshold = threshold; +} + +/* ================================================== */ + +void +REF_EnableLocal(int stratum, double distance, int orphan) +{ + enable_local_stratum = 1; + local_stratum = CLAMP(1, stratum, NTP_MAX_STRATUM - 1); + local_distance = distance; + local_orphan = !!orphan; +} + +/* ================================================== */ + +void +REF_DisableLocal(void) +{ + enable_local_stratum = 0; +} + +/* ================================================== */ + +#define LEAP_SECOND_CLOSE 5 + +static int +is_leap_close(time_t t) +{ + return leap_when != 0 && + t >= leap_when - LEAP_SECOND_CLOSE && t < leap_when + LEAP_SECOND_CLOSE; +} + +/* ================================================== */ + +int REF_IsLeapSecondClose(struct timespec *ts, double offset) +{ + struct timespec now, now_raw; + + SCH_GetLastEventTime(&now, NULL, &now_raw); + + if (is_leap_close(now.tv_sec) || is_leap_close(now_raw.tv_sec)) + return 1; + + if (ts && (is_leap_close(ts->tv_sec) || is_leap_close(ts->tv_sec + offset))) + return 1; + + return 0; +} + +/* ================================================== */ + +int +REF_GetTaiOffset(struct timespec *ts) +{ + int tai_offset; + + get_tz_leap(ts->tv_sec, &tai_offset); + + return tai_offset; +} + +/* ================================================== */ + +void +REF_GetTrackingReport(RPT_TrackingReport *rep) +{ + struct timespec now_raw, now_cooked; + double correction; + int synchronised; + + LCL_ReadRawTime(&now_raw); + LCL_GetOffsetCorrection(&now_raw, &correction, NULL); + UTI_AddDoubleToTimespec(&now_raw, correction, &now_cooked); + + REF_GetReferenceParams(&now_cooked, &synchronised, + &rep->leap_status, &rep->stratum, + &rep->ref_id, &rep->ref_time, + &rep->root_delay, &rep->root_dispersion); + + if (rep->stratum == NTP_MAX_STRATUM && !synchronised) + rep->stratum = 0; + + rep->ip_addr.family = IPADDR_UNSPEC; + rep->current_correction = correction; + rep->freq_ppm = LCL_ReadAbsoluteFrequency(); + rep->resid_freq_ppm = 0.0; + rep->skew_ppm = 0.0; + rep->last_update_interval = last_ref_update_interval; + rep->last_offset = last_offset; + rep->rms_offset = sqrt(avg2_offset); + + if (synchronised) { + rep->ip_addr = our_ref_ip; + rep->resid_freq_ppm = 1.0e6 * our_residual_freq; + rep->skew_ppm = 1.0e6 * our_skew; + } +} |