Esempio n. 1
0
/*
** set_time applies 'offset' to the local clock.
*/
int
set_time(
	double offset
	)
{
	int rc;

	if (time_adjusted)
		return EX_OK;

	/*
	** If we can step but we cannot slew, then step.
	** If we can step or slew and and |offset| > steplimit, then step.
	*/
	if (ENABLED_OPT(STEP) &&
	    (   !ENABLED_OPT(SLEW)
	     || (ENABLED_OPT(SLEW) && (fabs(offset) > steplimit))
	    )) {
		rc = step_systime(offset);

		/* If there was a problem, can we rely on errno? */
		if (1 == rc)
			time_adjusted = TRUE;
		return (time_adjusted)
			   ? EX_OK 
			   : 1;
		/*
		** In case of error, what should we use?
		** EX_UNAVAILABLE?
		** EX_OSERR?
		** EX_NOPERM?
		*/
	}

	if (ENABLED_OPT(SLEW)) {
		rc = adj_systime(offset);

		/* If there was a problem, can we rely on errno? */
		if (1 == rc)
			time_adjusted = TRUE;
		return (time_adjusted)
			   ? EX_OK 
			   : 1;
		/*
		** In case of error, what should we use?
		** EX_UNAVAILABLE?
		** EX_OSERR?
		** EX_NOPERM?
		*/
	}

	return EX_SOFTWARE;
}
Esempio n. 2
0
/*
 * timer - event timer
 */
void
timer(void)
{
	register struct peer *peer, *next_peer;
	u_int	n;
	long delta;

	/*
	 * The basic timerevent is one second. This is used to adjust
	 * the system clock in time and frequency, implement the
	 * kiss-o'-deatch function and implement the association
	 * polling function..
	 */
	current_time += nap_time;
	get_systime(&sys_time);
	nap_time = (u_long)-1;

	if (do_adjtime) {
		if (adjust_timer <= current_time) {
			adjust_timer += 1;
			adj_host_clock();
#ifdef REFCLOCK
			for (n = 0; n < NTP_HASH_SIZE; n++) {
				for (peer = peer_hash[n]; peer != 0; peer = next_peer) {
					next_peer = peer->next;
					if (peer->flags & FLAG_REFCLOCK)
						refclock_timer(peer);
				}
			}
#endif /* REFCLOCK */
		}
        nap_time = 1;
    }
    
    if (awake_timer) {
        if (awake_timer <= current_time) {
            for (n = 0; n < NTP_HASH_SIZE; n++) {
                for (peer = peer_hash[n]; peer != 0; peer = peer->next) {
                    peer->burst = NSTAGE;
                    peer->nextdate = current_time;
                    peer->throttle = 0;
                }
            }
            allow_panic = TRUE; /* Allow for large time offsets */
            init_loopfilter();
            state = EVNT_NSET;
            awake_timer = 0;
        } else {
            delta = awake_timer - current_time;
            if (delta < nap_time) {
                nap_time = delta;
            }
        }
    }
 
	/*
	 * Now dispatch any peers whose event timer has expired. Be
	 * careful here, since the peer structure might go away as the
	 * result of the call.
	 */
	for (n = 0; n < NTP_HASH_SIZE; n++) {
		for (peer = peer_hash[n]; peer != 0; peer = next_peer) {
			next_peer = peer->next;
			if (peer->action && peer->nextaction <= current_time)
				peer->action(peer);

			/*
			 * Restrain the non-burst packet rate not more
			 * than one packet every 16 seconds. This is
			 * usually tripped using iburst and minpoll of
			 * 128 s or less.
			 */
			if (peer->throttle > 0)
				peer->throttle--;
			if (peer->nextdate <= current_time) {
#ifdef REFCLOCK
				if (peer->flags & FLAG_REFCLOCK)
					refclock_transmit(peer);
				else
					transmit(peer);
#else /* REFCLOCK */
				transmit(peer);
#endif /* REFCLOCK */
			}

			if (peer->action && peer->nextaction >= current_time) {
				delta = peer->nextaction - current_time;
				if (delta < nap_time) {
                    nap_time = delta;
                }
			} else if (peer->nextdate >= current_time) {
                delta = peer->nextdate - current_time;
                if (delta < nap_time) {
                    nap_time = delta;
                }
            }
		}
	}

	/*
	 * Orphan mode is active when enabled and when no servers less
	 * than the orphan statum are available. A server with no other
	 * synchronization source is an orphan It shows offset zero and
	 * reference ID the loopback address.
	 */
	if (sys_orphan < STRATUM_UNSPEC && sys_peer == NULL) {
		if (sys_leap == LEAP_NOTINSYNC) {
			sys_leap = LEAP_NOWARNING;
#ifdef OPENSSL
			if (crypto_flags)	
				crypto_update();
#endif /* OPENSSL */
		}
		sys_stratum = (u_char)sys_orphan;
		if (sys_stratum > 1)
			sys_refid = htonl(LOOPBACKADR);
		else
			memcpy(&sys_refid, "LOOP", 4);
		sys_offset = 0;
		sys_rootdelay = 0;
		sys_rootdisp = 0;
	}

	/*
	 * Leapseconds. If a leap is pending, decrement the time
	 * remaining. If less than one day remains, set the leap bits.
	 * When no time remains, clear the leap bits and increment the
	 * TAI. If kernel suppport is not available, do the leap
	 * crudely. Note a leap cannot be pending unless the clock is
	 * set.
	 */
	if (leapsec > 0) {
		leapsec--;
		if (leapsec == 0) {
			sys_leap = LEAP_NOWARNING;
			sys_tai = leap_tai;
#ifdef KERNEL_PLL
			if (!(pll_control && kern_enable))
				step_systime(-1.0);
#else /* KERNEL_PLL */
#ifndef SYS_WINNT /* WinNT port has its own leap second handling */
			step_systime(-1.0);
#endif /* SYS_WINNT */
#endif /* KERNEL_PLL */
			report_event(EVNT_LEAP, NULL, NULL);
		} else {
			if (leapsec < DAY)
				sys_leap = LEAP_ADDSECOND;
			if (leap_tai > 0)
				sys_tai = leap_tai - 1;
		}
	}

	/*
	 * Update huff-n'-puff filter.
	 */
	if (huffpuff_timer <= current_time) {
		huffpuff_timer += HUFFPUFF;
		huffpuff();
	}

	if (huffpuff_timer >= current_time) {
		delta = huffpuff_timer - current_time;
		if (delta < nap_time) {
            nap_time = delta;
        }
	}

#ifdef OPENSSL
	/*
	 * Garbage collect expired keys.
	 */
	if (keys_timer <= current_time) {
		keys_timer += 1 << sys_automax;
		auth_agekeys();
	}

	if (keys_timer >= current_time) {
		delta = keys_timer - current_time;
		if (delta < nap_time) {
            nap_time = delta;
        }
	}

	/*
	 * Garbage collect key list and generate new private value. The
	 * timer runs only after initial synchronization and fires about
	 * once per day.
	 */
	if (revoke_timer <= current_time && sys_leap !=
	    LEAP_NOTINSYNC) {
		revoke_timer += 1 << sys_revoke;
		RAND_bytes((u_char *)&sys_private, 4);
	}

	if (revoke_timer >= current_time) {
		delta = revoke_timer - current_time;
		if (delta < nap_time) {
            nap_time = delta;
        }
	}
#endif /* OPENSSL */

	/*
	 * Interface update timer
	 */
	if (interface_interval && interface_timer <= current_time) {

		timer_interfacetimeout(current_time +
		    interface_interval);
		DPRINTF(2, ("timer: interface update\n"));
		interface_update(NULL, NULL);
	}
    if (interface_interval && interface_timer >= current_time) {
        delta = interface_timer - current_time;
        if (delta < nap_time) {
            nap_time = delta;
        }
    }

	if (dns_timer && (dns_timer <= current_time)) {
		dns_timer = update_dns_peers();
	}

	if (dns_timer >= current_time) {
		delta = dns_timer - current_time;
		if (delta < nap_time) {
            nap_time = delta;
        }
	}

	/*
	 * Finally, write hourly stats.
	 */
	if (stats_timer <= current_time) {
		stats_timer += HOUR;
		write_stats();
		if (sys_tai != 0 && sys_time.l_ui > leap_expire)
			report_event(EVNT_LEAPVAL, NULL, NULL);
	} else if (!do_adjtime && drift_file_sw) {
        write_stats(); /* update more frequently for pacemaker */
    }
	
	if (stats_timer >= current_time) {
		delta = stats_timer - current_time;
		if (delta < nap_time) {
            nap_time = delta;
        }
	}

    if (nap_time == 0) {
        nap_time = 1;
    }
    if (debug) {
        msyslog(LOG_INFO, "%s: current_time: %ld, nap_time: %ld", __FUNCTION__,
                current_time, nap_time);
    }
	itimer.it_interval.tv_sec = itimer.it_value.tv_sec = nap_time;
	setitimer(ITIMER_REAL, &itimer, (struct itimerval *)0);
}
Esempio n. 3
0
/*
 * local_clock - the NTP logical clock loop filter.
 *
 * Return codes:
 * -1	update ignored: exceeds panic threshold
 * 0	update ignored: popcorn or exceeds step threshold
 * 1	clock was slewed
 * 2	clock was stepped
 *
 * LOCKCLOCK: The only thing this routine does is set the
 * sys_rootdisp variable equal to the peer dispersion.
 */
int
local_clock(
	struct	peer *peer,	/* synch source peer structure */
	double	fp_offset	/* clock offset (s) */
	)
{
	int	rval;		/* return code */
	int	osys_poll;	/* old system poll */
	int	ntp_adj_ret;	/* returned by ntp_adjtime */
	double	mu;		/* interval since last update */
	double	clock_frequency; /* clock frequency */
	double	dtemp, etemp;	/* double temps */
	char	tbuf[80];	/* report buffer */

	/*
	 * If the loop is opened or the NIST LOCKCLOCK is in use,
	 * monitor and record the offsets anyway in order to determine
	 * the open-loop response and then go home.
	 */
#ifdef LOCKCLOCK
	{
#else
	if (!ntp_enable) {
#endif /* LOCKCLOCK */
		record_loop_stats(fp_offset, drift_comp, clock_jitter,
		    clock_stability, sys_poll);
		return (0);
	}

#ifndef LOCKCLOCK
	/*
	 * If the clock is way off, panic is declared. The clock_panic
	 * defaults to 1000 s; if set to zero, the panic will never
	 * occur. The allow_panic defaults to FALSE, so the first panic
	 * will exit. It can be set TRUE by a command line option, in
	 * which case the clock will be set anyway and time marches on.
	 * But, allow_panic will be set FALSE when the update is less
	 * than the step threshold; so, subsequent panics will exit.
	 */
	if (fabs(fp_offset) > clock_panic && clock_panic > 0 &&
	    !allow_panic) {
		snprintf(tbuf, sizeof(tbuf),
		    "%+.0f s; set clock manually within %.0f s.",
		    fp_offset, clock_panic);
		report_event(EVNT_SYSFAULT, NULL, tbuf);
		return (-1);
	}

	/*
	 * This section simulates ntpdate. If the offset exceeds the
	 * step threshold (128 ms), step the clock to that time and
	 * exit. Otherwise, slew the clock to that time and exit. Note
	 * that the slew will persist and eventually complete beyond the
	 * life of this program. Note that while ntpdate is active, the
	 * terminal does not detach, so the termination message prints
	 * directly to the terminal.
	 */
	if (mode_ntpdate) {
		if (  ( fp_offset > clock_max_fwd  && clock_max_fwd  > 0)
		   || (-fp_offset > clock_max_back && clock_max_back > 0)) {
			step_systime(fp_offset);
			msyslog(LOG_NOTICE, "ntpd: time set %+.6f s",
			    fp_offset);
			printf("ntpd: time set %+.6fs\n", fp_offset);
		} else {
			adj_systime(fp_offset);
			msyslog(LOG_NOTICE, "ntpd: time slew %+.6f s",
			    fp_offset);
			printf("ntpd: time slew %+.6fs\n", fp_offset);
		}
		record_loop_stats(fp_offset, drift_comp, clock_jitter,
		    clock_stability, sys_poll);
		exit (0);
	}

	/*
	 * The huff-n'-puff filter finds the lowest delay in the recent
	 * interval. This is used to correct the offset by one-half the
	 * difference between the sample delay and minimum delay. This
	 * is most effective if the delays are highly assymetric and
	 * clockhopping is avoided and the clock frequency wander is
	 * relatively small.
	 */
	if (sys_huffpuff != NULL) {
		if (peer->delay < sys_huffpuff[sys_huffptr])
			sys_huffpuff[sys_huffptr] = peer->delay;
		if (peer->delay < sys_mindly)
			sys_mindly = peer->delay;
		if (fp_offset > 0)
			dtemp = -(peer->delay - sys_mindly) / 2;
		else
			dtemp = (peer->delay - sys_mindly) / 2;
		fp_offset += dtemp;
#ifdef DEBUG
		if (debug)
			printf(
		    "local_clock: size %d mindly %.6f huffpuff %.6f\n",
			    sys_hufflen, sys_mindly, dtemp);
#endif
	}

	/*
	 * Clock state machine transition function which defines how the
	 * system reacts to large phase and frequency excursion. There
	 * are two main regimes: when the offset exceeds the step
	 * threshold (128 ms) and when it does not. Under certain
	 * conditions updates are suspended until the stepout theshold
	 * (900 s) is exceeded. See the documentation on how these
	 * thresholds interact with commands and command line options.
	 *
	 * Note the kernel is disabled if step is disabled or greater
	 * than 0.5 s or in ntpdate mode.
	 */
	osys_poll = sys_poll;
	if (sys_poll < peer->minpoll)
		sys_poll = peer->minpoll;
	if (sys_poll > peer->maxpoll)
		sys_poll = peer->maxpoll;
	mu = current_time - clock_epoch;
	clock_frequency = drift_comp;
	rval = 1;
	if (  ( fp_offset > clock_max_fwd  && clock_max_fwd  > 0)
	   || (-fp_offset > clock_max_back && clock_max_back > 0)
	   || force_step_once ) {
		if (force_step_once) {
			force_step_once = FALSE;  /* we want this only once after startup */
			msyslog(LOG_NOTICE, "Doing intital time step" );
		}

		switch (state) {

		/*
		 * In SYNC state we ignore the first outlyer and switch
		 * to SPIK state.
		 */
		case EVNT_SYNC:
			snprintf(tbuf, sizeof(tbuf), "%+.6f s",
			    fp_offset);
			report_event(EVNT_SPIK, NULL, tbuf);
			state = EVNT_SPIK;
			return (0);

		/*
		 * In FREQ state we ignore outlyers and inlyers. At the
		 * first outlyer after the stepout threshold, compute
		 * the apparent frequency correction and step the phase.
		 */
		case EVNT_FREQ:
			if (mu < clock_minstep)
				return (0);

			clock_frequency = direct_freq(fp_offset);

			/* fall through to EVNT_SPIK */

		/*
		 * In SPIK state we ignore succeeding outlyers until
		 * either an inlyer is found or the stepout threshold is
		 * exceeded.
		 */
		case EVNT_SPIK:
			if (mu < clock_minstep)
				return (0);

			/* fall through to default */

		/*
		 * We get here by default in NSET and FSET states and
		 * from above in FREQ or SPIK states.
		 *
		 * In NSET state an initial frequency correction is not
		 * available, usually because the frequency file has not
		 * yet been written. Since the time is outside the step
		 * threshold, the clock is stepped. The frequency will
		 * be set directly following the stepout interval.
		 *
		 * In FSET state the initial frequency has been set from
		 * the frequency file. Since the time is outside the
		 * step threshold, the clock is stepped immediately,
		 * rather than after the stepout interval. Guys get
		 * nervous if it takes 15 minutes to set the clock for
		 * the first time.
		 *
		 * In FREQ and SPIK states the stepout threshold has
		 * expired and the phase is still above the step
		 * threshold. Note that a single spike greater than the
		 * step threshold is always suppressed, even with a
		 * long time constant.
		 */
		default:
			snprintf(tbuf, sizeof(tbuf), "%+.6f s",
			    fp_offset);
			report_event(EVNT_CLOCKRESET, NULL, tbuf);
			step_systime(fp_offset);
			reinit_timer();
			tc_counter = 0;
			clock_jitter = LOGTOD(sys_precision);
			rval = 2;
			if (state == EVNT_NSET) {
				rstclock(EVNT_FREQ, 0);
				return (rval);
			}
			break;
		}
		rstclock(EVNT_SYNC, 0);
	} else {
		/*
		 * The offset is less than the step threshold. Calculate
		 * the jitter as the exponentially weighted offset
		 * differences.
		 */
		etemp = SQUARE(clock_jitter);
		dtemp = SQUARE(max(fabs(fp_offset - last_offset),
		    LOGTOD(sys_precision)));
		clock_jitter = SQRT(etemp + (dtemp - etemp) /
		    CLOCK_AVG);
		switch (state) {

		/*
		 * In NSET state this is the first update received and
		 * the frequency has not been initialized. Adjust the
		 * phase, but do not adjust the frequency until after
		 * the stepout threshold.
		 */
		case EVNT_NSET:
			adj_systime(fp_offset);
			rstclock(EVNT_FREQ, fp_offset);
			break;

		/*
		 * In FREQ state ignore updates until the stepout
		 * threshold. After that, compute the new frequency, but
		 * do not adjust the frequency until the holdoff counter
		 * decrements to zero.
		 */
		case EVNT_FREQ:
			if (mu < clock_minstep)
				return (0);

			clock_frequency = direct_freq(fp_offset);
			/* fall through */

		/*
		 * We get here by default in FSET, SPIK and SYNC states.
		 * Here compute the frequency update due to PLL and FLL
		 * contributions. Note, we avoid frequency discipline at
		 * startup until the initial transient has subsided.
		 */
		default:
			allow_panic = FALSE;
			if (freq_cnt == 0) {

				/*
				 * The FLL and PLL frequency gain constants
				 * depend on the time constant and Allan
				 * intercept. The PLL is always used, but
				 * becomes ineffective above the Allan intercept
				 * where the FLL becomes effective.
				 */
				if (sys_poll >= allan_xpt)
					clock_frequency += (fp_offset -
					    clock_offset) / max(ULOGTOD(sys_poll),
					    mu) * CLOCK_FLL;

				/*
				 * The PLL frequency gain (numerator) depends on
				 * the minimum of the update interval and Allan
				 * intercept. This reduces the PLL gain when the
				 * FLL becomes effective.
				 */
				etemp = min(ULOGTOD(allan_xpt), mu);
				dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll);
				clock_frequency += fp_offset * etemp / (dtemp *
				    dtemp);
			}
			rstclock(EVNT_SYNC, fp_offset);
			if (fabs(fp_offset) < CLOCK_FLOOR)
				freq_cnt = 0;
			break;
		}
	}

#ifdef KERNEL_PLL
	/*
	 * This code segment works when clock adjustments are made using
	 * precision time kernel support and the ntp_adjtime() system
	 * call. This support is available in Solaris 2.6 and later,
	 * Digital Unix 4.0 and later, FreeBSD, Linux and specially
	 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
	 * DECstation 5000/240 and Alpha AXP, additional kernel
	 * modifications provide a true microsecond clock and nanosecond
	 * clock, respectively.
	 *
	 * Important note: The kernel discipline is used only if the
	 * step threshold is less than 0.5 s, as anything higher can
	 * lead to overflow problems. This might occur if some misguided
	 * lad set the step threshold to something ridiculous.
	 */
	if (pll_control && kern_enable && freq_cnt == 0) {

		/*
		 * We initialize the structure for the ntp_adjtime()
		 * system call. We have to convert everything to
		 * microseconds or nanoseconds first. Do not update the
		 * system variables if the ext_enable flag is set. In
		 * this case, the external clock driver will update the
		 * variables, which will be read later by the local
		 * clock driver. Afterwards, remember the time and
		 * frequency offsets for jitter and stability values and
		 * to update the frequency file.
		 */
		ZERO(ntv);
		if (ext_enable) {
			ntv.modes = MOD_STATUS;
		} else {
#ifdef STA_NANO
			ntv.modes = MOD_BITS | MOD_NANO;
#else /* STA_NANO */
			ntv.modes = MOD_BITS;
#endif /* STA_NANO */
			if (clock_offset < 0)
				dtemp = -.5;
			else
				dtemp = .5;
#ifdef STA_NANO
			ntv.offset = (int32)(clock_offset * 1e9 +
			    dtemp);
			ntv.constant = sys_poll;
#else /* STA_NANO */
			ntv.offset = (int32)(clock_offset * 1e6 +
			    dtemp);
			ntv.constant = sys_poll - 4;
#endif /* STA_NANO */
			if (ntv.constant < 0)
				ntv.constant = 0;

			ntv.esterror = (u_int32)(clock_jitter * 1e6);
			ntv.maxerror = (u_int32)((sys_rootdelay / 2 +
			    sys_rootdisp) * 1e6);
			ntv.status = STA_PLL;

			/*
			 * Enable/disable the PPS if requested.
			 */
			if (hardpps_enable) {
				ntv.status |= (STA_PPSTIME | STA_PPSFREQ);
				if (!(pll_status & STA_PPSTIME))
					sync_status("PPS enabled",
						pll_status,
						ntv.status);
			} else {
				ntv.status &= ~(STA_PPSTIME | STA_PPSFREQ);
				if (pll_status & STA_PPSTIME)
					sync_status("PPS disabled",
						pll_status,
						ntv.status);
			}
			if (sys_leap == LEAP_ADDSECOND)
				ntv.status |= STA_INS;
			else if (sys_leap == LEAP_DELSECOND)
				ntv.status |= STA_DEL;
		}

		/*
		 * Pass the stuff to the kernel. If it squeals, turn off
		 * the pps. In any case, fetch the kernel offset,
		 * frequency and jitter.
		 */
		ntp_adj_ret = ntp_adjtime(&ntv);
		/*
		 * A squeal is a return status < 0, or a state change.
		 */
		if ((0 > ntp_adj_ret) || (ntp_adj_ret != kernel_status)) {
			kernel_status = ntp_adj_ret;
			ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, hardpps_enable, 0, __LINE__ - 1);
		}
		pll_status = ntv.status;
#ifdef STA_NANO
		clock_offset = ntv.offset / 1e9;
#else /* STA_NANO */
		clock_offset = ntv.offset / 1e6;
#endif /* STA_NANO */
		clock_frequency = FREQTOD(ntv.freq);

		/*
		 * If the kernel PPS is lit, monitor its performance.
		 */
		if (ntv.status & STA_PPSTIME) {
#ifdef STA_NANO
			clock_jitter = ntv.jitter / 1e9;
#else /* STA_NANO */
			clock_jitter = ntv.jitter / 1e6;
#endif /* STA_NANO */
		}

#if defined(STA_NANO) && NTP_API == 4
		/*
		 * If the TAI changes, update the kernel TAI.
		 */
		if (loop_tai != sys_tai) {
			loop_tai = sys_tai;
			ntv.modes = MOD_TAI;
			ntv.constant = sys_tai;
			if ((ntp_adj_ret = ntp_adjtime(&ntv)) != 0) {
			    ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, 0, 1, __LINE__ - 1);
			}
		}
#endif /* STA_NANO */
	}
#endif /* KERNEL_PLL */

	/*
	 * Clamp the frequency within the tolerance range and calculate
	 * the frequency difference since the last update.
	 */
	if (fabs(clock_frequency) > NTP_MAXFREQ)
		msyslog(LOG_NOTICE,
		    "frequency error %.0f PPM exceeds tolerance %.0f PPM",
		    clock_frequency * 1e6, NTP_MAXFREQ * 1e6);
	dtemp = SQUARE(clock_frequency - drift_comp);
	if (clock_frequency > NTP_MAXFREQ)
		drift_comp = NTP_MAXFREQ;
	else if (clock_frequency < -NTP_MAXFREQ)
		drift_comp = -NTP_MAXFREQ;
	else
		drift_comp = clock_frequency;

	/*
	 * Calculate the wander as the exponentially weighted RMS
	 * frequency differences. Record the change for the frequency
	 * file update.
	 */
	etemp = SQUARE(clock_stability);
	clock_stability = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG);

	/*
	 * Here we adjust the time constant by comparing the current
	 * offset with the clock jitter. If the offset is less than the
	 * clock jitter times a constant, then the averaging interval is
	 * increased, otherwise it is decreased. A bit of hysteresis
	 * helps calm the dance. Works best using burst mode. Don't
	 * fiddle with the poll during the startup clamp period.
	 */
	if (freq_cnt > 0) {
		tc_counter = 0;
	} else if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) {
		tc_counter += sys_poll;
		if (tc_counter > CLOCK_LIMIT) {
			tc_counter = CLOCK_LIMIT;
			if (sys_poll < peer->maxpoll) {
				tc_counter = 0;
				sys_poll++;
			}
		}
	} else {
		tc_counter -= sys_poll << 1;
		if (tc_counter < -CLOCK_LIMIT) {
			tc_counter = -CLOCK_LIMIT;
			if (sys_poll > peer->minpoll) {
				tc_counter = 0;
				sys_poll--;
			}
		}
	}

	/*
	 * If the time constant has changed, update the poll variables.
	 */
	if (osys_poll != sys_poll)
		poll_update(peer, sys_poll);

	/*
	 * Yibbidy, yibbbidy, yibbidy; that'h all folks.
	 */
	record_loop_stats(clock_offset, drift_comp, clock_jitter,
	    clock_stability, sys_poll);
#ifdef DEBUG
	if (debug)
		printf(
		    "local_clock: offset %.9f jit %.9f freq %.3f stab %.3f poll %d\n",
		    clock_offset, clock_jitter, drift_comp * 1e6,
		    clock_stability * 1e6, sys_poll);
#endif /* DEBUG */
	return (rval);
#endif /* LOCKCLOCK */
}


/*
 * adj_host_clock - Called once every second to update the local clock.
 *
 * LOCKCLOCK: The only thing this routine does is increment the
 * sys_rootdisp variable.
 */
void
adj_host_clock(
	void
	)
{
	double	offset_adj;
	double	freq_adj;

	/*
	 * Update the dispersion since the last update. In contrast to
	 * NTPv3, NTPv4 does not declare unsynchronized after one day,
	 * since the dispersion check serves this function. Also,
	 * since the poll interval can exceed one day, the old test
	 * would be counterproductive. During the startup clamp period, the
	 * time constant is clamped at 2.
	 */
	sys_rootdisp += clock_phi;
#ifndef LOCKCLOCK
	if (!ntp_enable || mode_ntpdate)
		return;
	/*
	 * Determine the phase adjustment. The gain factor (denominator)
	 * increases with poll interval, so is dominated by the FLL
	 * above the Allan intercept. Note the reduced time constant at
	 * startup.
	 */
	if (state != EVNT_SYNC) {
		offset_adj = 0.;
	} else if (freq_cnt > 0) {
		offset_adj = clock_offset / (CLOCK_PLL * ULOGTOD(1));
		freq_cnt--;
#ifdef KERNEL_PLL
	} else if (pll_control && kern_enable) {
		offset_adj = 0.;
#endif /* KERNEL_PLL */
	} else {
		offset_adj = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll));
	}

	/*
	 * If the kernel discipline is enabled the frequency correction
	 * drift_comp has already been engaged via ntp_adjtime() in
	 * set_freq().  Otherwise it is a component of the adj_systime()
	 * offset.
	 */
#ifdef KERNEL_PLL
	if (pll_control && kern_enable)
		freq_adj = 0.;
	else
#endif /* KERNEL_PLL */
		freq_adj = drift_comp;

	/* Bound absolute value of total adjustment to NTP_MAXFREQ. */
	if (offset_adj + freq_adj > NTP_MAXFREQ)
		offset_adj = NTP_MAXFREQ - freq_adj;
	else if (offset_adj + freq_adj < -NTP_MAXFREQ)
		offset_adj = -NTP_MAXFREQ - freq_adj;

	clock_offset -= offset_adj;
	/*
	 * Windows port adj_systime() must be called each second,
	 * even if the argument is zero, to ease emulation of
	 * adjtime() using Windows' slew API which controls the rate
	 * but does not automatically stop slewing when an offset
	 * has decayed to zero.
	 */
	adj_systime(offset_adj + freq_adj);
#endif /* LOCKCLOCK */
}
Esempio n. 4
0
static void
check_leapsec(
	u_int32        now  ,
	const time_t * tpiv ,
        int/*BOOL*/    reset)
{
	static const char leapmsg_p_step[] =
	    "Positive leap second, stepped backward.";
	static const char leapmsg_p_slew[] =
	    "Positive leap second, no step correction. "
	    "System clock will be inaccurate for a long time.";

	static const char leapmsg_n_step[] =
	    "Negative leap second, stepped forward.";
	static const char leapmsg_n_slew[] =
	    "Negative leap second, no step correction. "
	    "System clock will be inaccurate for a long time.";

	leap_result_t lsdata;
	u_int32       lsprox;
#ifdef AUTOKEY
	int/*BOOL*/   update_autokey = FALSE;
#endif

#ifndef SYS_WINNT  /* WinNT port has its own leap second handling */
# ifdef KERNEL_PLL
	leapsec_electric(pll_control && kern_enable);
# else
	leapsec_electric(0);
# endif
#endif
#ifdef LEAP_SMEAR
	leap_smear.enabled = leap_smear_intv != 0;
#endif
	if (reset)	{
		lsprox = LSPROX_NOWARN;
		leapsec_reset_frame();
		memset(&lsdata, 0, sizeof(lsdata));
	} else {
	  int fired = leapsec_query(&lsdata, now, tpiv);

	  DPRINTF(1, ("*** leapsec_query: fired %i, now %u (0x%08X), tai_diff %i, ddist %u\n",
		  fired, now, now, lsdata.tai_diff, lsdata.ddist));

#ifdef LEAP_SMEAR
	  leap_smear.in_progress = 0;
	  leap_smear.doffset = 0.0;

	  if (leap_smear.enabled) {
		if (lsdata.tai_diff) {
			if (leap_smear.interval == 0) {
				leap_smear.interval = leap_smear_intv;
				leap_smear.intv_end = lsdata.ttime.Q_s;
				leap_smear.intv_start = leap_smear.intv_end - leap_smear.interval;
				DPRINTF(1, ("*** leapsec_query: setting leap_smear interval %li, begin %.0f, end %.0f\n",
					leap_smear.interval, leap_smear.intv_start, leap_smear.intv_end));
			}
		}
		else {
			if (leap_smear.interval)
				DPRINTF(1, ("*** leapsec_query: clearing leap_smear interval\n"));
			leap_smear.interval = 0;
		}

		if (leap_smear.interval) {
			double dtemp = now;
			if (dtemp >= leap_smear.intv_start && dtemp <= leap_smear.intv_end) {
				double leap_smear_time = dtemp - leap_smear.intv_start;
				/*
				 * For now we just do a linear interpolation over the smear interval
				 */
#if 0
				// linear interpolation
				leap_smear.doffset = -(leap_smear_time * lsdata.tai_diff / leap_smear.interval);
#else
				// Google approach: lie(t) = (1.0 - cos(pi * t / w)) / 2.0
				leap_smear.doffset = -((double) lsdata.tai_diff - cos( M_PI * leap_smear_time / leap_smear.interval)) / 2.0;
#endif
				/*
				 * TODO see if we're inside an inserted leap second, so we need to compute
				 * leap_smear.doffset = 1.0 - leap_smear.doffset
				 */
				leap_smear.in_progress = 1;
#if 0 && defined( DEBUG )
				msyslog(LOG_NOTICE, "*** leapsec_query: [%.0f:%.0f] (%li), now %u (%.0f), smear offset %.6f ms\n",
					leap_smear.intv_start, leap_smear.intv_end, leap_smear.interval,
					now, leap_smear_time, leap_smear.doffset);
#else
				DPRINTF(1, ("*** leapsec_query: [%.0f:%.0f] (%li), now %u (%.0f), smear offset %.6f ms\n",
					leap_smear.intv_start, leap_smear.intv_end, leap_smear.interval,
					now, leap_smear_time, leap_smear.doffset));
#endif

			}
		}
	  }
	  else
		leap_smear.interval = 0;

	  /*
	   * Update the current leap smear offset, eventually 0.0 if outside smear interval.
	   */
	  DTOLFP(leap_smear.doffset, &leap_smear.offset);

#endif	/* LEAP_SMEAR */

	  if (fired) {
		/* Full hit. Eventually step the clock, but always
		 * announce the leap event has happened.
		 */
		const char *leapmsg = NULL;
		if (lsdata.warped < 0) {
			if (clock_max_back > 0.0 &&
			    clock_max_back < abs(lsdata.warped)) {
				step_systime(lsdata.warped);
				leapmsg = leapmsg_p_step;
			} else {
				leapmsg = leapmsg_p_slew;
			}
		} else 	if (lsdata.warped > 0) {
			if (clock_max_fwd > 0.0 &&
			    clock_max_fwd < abs(lsdata.warped)) {
				step_systime(lsdata.warped);
				leapmsg = leapmsg_n_step;
			} else {
				leapmsg = leapmsg_n_slew;
			}
		}
		if (leapmsg)
			msyslog(LOG_NOTICE, "%s", leapmsg);
		report_event(EVNT_LEAP, NULL, NULL);
#ifdef AUTOKEY
		update_autokey = TRUE;
#endif
		lsprox  = LSPROX_NOWARN;
		leapsec = LSPROX_NOWARN;
		sys_tai = lsdata.tai_offs;
	  } else {
#ifdef AUTOKEY
		update_autokey = (sys_tai != (u_int)lsdata.tai_offs);
#endif
		lsprox  = lsdata.proximity;
		sys_tai = lsdata.tai_offs;
	  }
	}

	/* We guard against panic alarming during the red alert phase.
	 * Strange and evil things might happen if we go from stone cold
	 * to piping hot in one step. If things are already that wobbly,
	 * we let the normal clock correction take over, even if a jump
	 * is involved.
         * Also make sure the alarming events are edge-triggered, that is,
         * ceated only when the threshold is crossed.
         */
	if (  (leapsec > 0 || lsprox < LSPROX_ALERT)
	    && leapsec < lsprox                     ) {
		if (  leapsec < LSPROX_SCHEDULE
                   && lsprox >= LSPROX_SCHEDULE) {
			if (lsdata.dynamic)
				report_event(PEVNT_ARMED, sys_peer, NULL);
			else
				report_event(EVNT_ARMED, NULL, NULL);
		}
		leapsec = lsprox;
	}
	if (leapsec > lsprox) {
		if (  leapsec >= LSPROX_SCHEDULE
                   && lsprox   < LSPROX_SCHEDULE) {
			report_event(EVNT_DISARMED, NULL, NULL);
		}
		leapsec = lsprox;
	}

	if (leapsec >= LSPROX_SCHEDULE)
		leapdif = lsdata.tai_diff;
	else
		leapdif = 0;

	check_leap_sec_in_progress(&lsdata);

#ifdef AUTOKEY
	if (update_autokey)
		crypto_update_taichange();
#endif
}
Esempio n. 5
0
static void
check_leapsec(
	u_int32        now  ,
	const time_t * tpiv ,
        int/*BOOL*/    reset)
{
	leap_result_t lsdata;
	u_int32       lsprox;
	
#ifndef SYS_WINNT  /* WinNT port has its own leap second handling */
# ifdef KERNEL_PLL
	leapsec_electric(pll_control && kern_enable);
# else
	leapsec_electric(0);
# endif
#endif	
	if (reset)	{
		lsprox = LSPROX_NOWARN;
		leapsec_reset_frame();
		memset(&lsdata, 0, sizeof(lsdata));
	} else if (leapsec_query(&lsdata, now, tpiv)) {
		/* Full hit. Eventually step the clock, but always
		 * announce the leap event has happened.
		 */
		if (lsdata.warped < 0) {
			step_systime(lsdata.warped);
			msyslog(LOG_NOTICE, "Inserting positive leap second.");
		} else 	if (lsdata.warped > 0) {
			step_systime(lsdata.warped);
			msyslog(LOG_NOTICE, "Inserting negative leap second.");
		}
		report_event(EVNT_LEAP, NULL, NULL);
		lsprox  = LSPROX_NOWARN;
		leapsec = LSPROX_NOWARN;
		sys_tai = lsdata.tai_offs;
	} else {
		lsprox  = lsdata.proximity;
		sys_tai = lsdata.tai_offs;
	}

	/* We guard against panic alarming during the red alert phase.
	 * Strange and evil things might happen if we go from stone cold
	 * to piping hot in one step. If things are already that wobbly,
	 * we let the normal clock correction take over, even if a jump
	 * is involved.
         * Also make sure the alarming events are edge-triggered, that is,
         * ceated only when the threshold is crossed.
         */
	if (  (leapsec > 0 || lsprox < LSPROX_ALERT)
	    && leapsec < lsprox                     ) {
		if (  leapsec < LSPROX_SCHEDULE
                   && lsprox >= LSPROX_SCHEDULE) {
			if (lsdata.dynamic)
				report_event(PEVNT_ARMED, sys_peer, NULL);
			else
				report_event(EVNT_ARMED, NULL, NULL);
		}
		leapsec = lsprox;
	}
	if (leapsec > lsprox) {
		if (  leapsec >= LSPROX_SCHEDULE
                   && lsprox   < LSPROX_SCHEDULE) {
			report_event(EVNT_DISARMED, NULL, NULL);
		}
		leapsec = lsprox;
	}

        if (leapsec >= LSPROX_SCHEDULE)
                leapdif = lsdata.tai_diff;
        else
                leapdif = 0;
}
Esempio n. 6
0
/*
 * local_clock - the NTP logical clock loop filter.
 *
 * Return codes:
 * -1	update ignored: exceeds panic threshold
 * 0	update ignored: popcorn or exceeds step threshold
 * 1	clock was slewed
 * 2	clock was stepped
 *
 * LOCKCLOCK: The only thing this routine does is set the
 * sys_rootdispersion variable equal to the peer dispersion.
 */
int
local_clock(
	struct	peer *peer,	/* synch source peer structure */
	double	fp_offset	/* clock offset (s) */
	)
{
	int	rval;		/* return code */
	u_long	mu;		/* interval since last update (s) */
	double	flladj;		/* FLL frequency adjustment (ppm) */
	double	plladj;		/* PLL frequency adjustment (ppm) */
	double	clock_frequency; /* clock frequency adjustment (ppm) */
	double	dtemp, etemp;	/* double temps */
#ifdef OPENSSL
	u_int32 *tpt;
	int	i;
	u_int	len;
	long	togo;
#endif /* OPENSSL */

	/*
	 * If the loop is opened or the NIST LOCKCLOCK is in use,
	 * monitor and record the offsets anyway in order to determine
	 * the open-loop response and then go home.
	 */
#ifdef DEBUG
	if (debug)
		printf(
		    "local_clock: assocID %d offset %.9f freq %.3f state %d\n",
		    peer->associd, fp_offset, drift_comp * 1e6, state);
#endif
#ifdef LOCKCLOCK
	return (0);

#else /* LOCKCLOCK */
	if (!ntp_enable) {
		record_loop_stats(fp_offset, drift_comp, clock_jitter,
		    clock_stability, sys_poll);
		return (0);
	}

	/*
	 * If the clock is way off, panic is declared. The clock_panic
	 * defaults to 1000 s; if set to zero, the panic will never
	 * occur. The allow_panic defaults to FALSE, so the first panic
	 * will exit. It can be set TRUE by a command line option, in
	 * which case the clock will be set anyway and time marches on.
	 * But, allow_panic will be set FALSE when the update is less
	 * than the step threshold; so, subsequent panics will exit.
	 */
	if (fabs(fp_offset) > clock_panic && clock_panic > 0 &&
	    !allow_panic) {
		msyslog(LOG_ERR,
		    "time correction of %.0f seconds exceeds sanity limit (%.0f); set clock manually to the correct UTC time.",
		    fp_offset, clock_panic);
		return (-1);
	}

	/*
	 * If simulating ntpdate, set the clock directly, rather than
	 * using the discipline. The clock_max defines the step
	 * threshold, above which the clock will be stepped instead of
	 * slewed. The value defaults to 128 ms, but can be set to even
	 * unreasonable values. If set to zero, the clock will never be
	 * stepped. Note that a slew will persist beyond the life of
	 * this program.
	 *
	 * Note that if ntpdate is active, the terminal does not detach,
	 * so the termination comments print directly to the console.
	 */
	if (mode_ntpdate) {
		if (fabs(fp_offset) > clock_max && clock_max > 0) {
			step_systime(fp_offset);
			msyslog(LOG_NOTICE, "time reset %+.6f s",
	   		    fp_offset);
			printf("ntpd: time set %+.6fs\n", fp_offset);
		} else {
			adj_systime(fp_offset);
			msyslog(LOG_NOTICE, "time slew %+.6f s",
			    fp_offset);
			printf("ntpd: time slew %+.6fs\n", fp_offset);
		}
		record_loop_stats(fp_offset, drift_comp, clock_jitter,
		    clock_stability, sys_poll);
		exit (0);
	}

	/*
	 * The huff-n'-puff filter finds the lowest delay in the recent
	 * interval. This is used to correct the offset by one-half the
	 * difference between the sample delay and minimum delay. This
	 * is most effective if the delays are highly assymetric and
	 * clockhopping is avoided and the clock frequency wander is
	 * relatively small.
	 *
	 * Note either there is no prefer peer or this update is from
	 * the prefer peer.
	 */
	if (sys_huffpuff != NULL && (sys_prefer == NULL || sys_prefer ==
	    peer)) {
		if (peer->delay < sys_huffpuff[sys_huffptr])
			sys_huffpuff[sys_huffptr] = peer->delay;
		if (peer->delay < sys_mindly)
			sys_mindly = peer->delay;
		if (fp_offset > 0)
			dtemp = -(peer->delay - sys_mindly) / 2;
		else
			dtemp = (peer->delay - sys_mindly) / 2;
		fp_offset += dtemp;
#ifdef DEBUG
		if (debug)
			printf(
		    "local_clock: size %d mindly %.6f huffpuff %.6f\n",
			    sys_hufflen, sys_mindly, dtemp);
#endif
	}

	/*
	 * Clock state machine transition function. This is where the
	 * action is and defines how the system reacts to large phase
	 * and frequency errors. There are two main regimes: when the
	 * offset exceeds the step threshold and when it does not.
	 * However, if the step threshold is set to zero, a step will
	 * never occur. See the instruction manual for the details how
	 * these actions interact with the command line options.
	 *
	 * Note the system poll is set to minpoll only if the clock is
	 * stepped. Note also the kernel is disabled if step is
	 * disabled or greater than 0.5 s. 
	 */
	clock_frequency = flladj = plladj = 0;
	mu = peer->epoch - sys_clocktime;
	if (clock_max == 0 || clock_max > 0.5)
		kern_enable = 0;
	rval = 1;
	if (fabs(fp_offset) > clock_max && clock_max > 0) {
		switch (state) {

		/*
		 * In S_SYNC state we ignore the first outlyer amd
		 * switch to S_SPIK state.
		 */
		case S_SYNC:
			state = S_SPIK;
			return (0);

		/*
		 * In S_FREQ state we ignore outlyers and inlyers. At
		 * the first outlyer after the stepout threshold,
		 * compute the apparent frequency correction and step
		 * the phase.
		 */
		case S_FREQ:
			if (mu < clock_minstep)
				return (0);

			clock_frequency = (fp_offset - clock_offset) /
			    mu;

			/* fall through to S_SPIK */

		/*
		 * In S_SPIK state we ignore succeeding outlyers until
		 * either an inlyer is found or the stepout threshold is
		 * exceeded.
		 */
		case S_SPIK:
			if (mu < clock_minstep)
				return (0);

			/* fall through to default */

		/*
		 * We get here by default in S_NSET and S_FSET states
		 * and from above in S_FREQ or S_SPIK states.
		 *
		 * In S_NSET state an initial frequency correction is
		 * not available, usually because the frequency file has
		 * not yet been written. Since the time is outside the
		 * step threshold, the clock is stepped. The frequency
		 * will be set directly following the stepout interval.
		 *
		 * In S_FSET state the initial frequency has been set
		 * from the frequency file. Since the time is outside
		 * the step threshold, the clock is stepped immediately,
		 * rather than after the stepout interval. Guys get
		 * nervous if it takes 17 minutes to set the clock for
		 * the first time.
		 *
		 * In S_FREQ and S_SPIK states the stepout threshold has
		 * expired and the phase is still above the step
		 * threshold. Note that a single spike greater than the
		 * step threshold is always suppressed, even at the
		 * longer poll intervals.
		 */ 
		default:
			step_systime(fp_offset);
			msyslog(LOG_NOTICE, "time reset %+.6f s",
			    fp_offset);
			reinit_timer();
			tc_counter = 0;
			sys_poll = NTP_MINPOLL;
			sys_tai = 0;
			clock_jitter = LOGTOD(sys_precision);
			rval = 2;
			if (state == S_NSET) {
				rstclock(S_FREQ, peer->epoch, 0);
				return (rval);
			}
			break;
		}
		rstclock(S_SYNC, peer->epoch, 0);
	} else {

		/*
		 * The offset is less than the step threshold. Calculate
		 * the jitter as the exponentially weighted offset
		 * differences.
 	      	 */
		etemp = SQUARE(clock_jitter);
		dtemp = SQUARE(max(fabs(fp_offset - last_offset),
		    LOGTOD(sys_precision)));
		clock_jitter = SQRT(etemp + (dtemp - etemp) /
		    CLOCK_AVG);
		switch (state) {

		/*
		 * In S_NSET state this is the first update received and
		 * the frequency has not been initialized. Adjust the
		 * phase, but do not adjust the frequency until after
		 * the stepout threshold.
		 */
		case S_NSET:
			rstclock(S_FREQ, peer->epoch, fp_offset);
			break;

		/*
		 * In S_FSET state this is the first update received and
		 * the frequency has been initialized. Adjust the phase,
		 * but do not adjust the frequency until the next
		 * update.
		 */
		case S_FSET:
			rstclock(S_SYNC, peer->epoch, fp_offset);
			break;

		/*
		 * In S_FREQ state ignore updates until the stepout
		 * threshold. After that, correct the phase and
		 * frequency and switch to S_SYNC state.
		 */
		case S_FREQ:
			if (mu < clock_minstep)
				return (0);

			clock_frequency = (fp_offset - clock_offset) /
			    mu;
			rstclock(S_SYNC, peer->epoch, fp_offset);
			break;

		/*
		 * We get here by default in S_SYNC and S_SPIK states.
		 * Here we compute the frequency update due to PLL and
		 * FLL contributions.
		 */
		default:
			allow_panic = FALSE;

			/*
			 * The FLL and PLL frequency gain constants
			 * depend on the poll interval and Allan
			 * intercept. The PLL is always used, but
			 * becomes ineffective above the Allan
			 * intercept. The FLL is not used below one-half
			 * the Allan intercept. Above that the loop gain
			 * increases in steps to 1 / CLOCK_AVG. 
			 */
			if (ULOGTOD(sys_poll) > allan_xpt / 2) {
				dtemp = CLOCK_FLL - sys_poll;
				flladj = (fp_offset - clock_offset) /
				    (max(mu, allan_xpt) * dtemp);
			}

			/*
			 * For the PLL the integration interval
			 * (numerator) is the minimum of the update
			 * interval and poll interval. This allows
			 * oversampling, but not undersampling.
			 */ 
			etemp = min(mu, (u_long)ULOGTOD(sys_poll));
			dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll);
			plladj = fp_offset * etemp / (dtemp * dtemp);
			rstclock(S_SYNC, peer->epoch, fp_offset);
			break;
		}
	}

#ifdef OPENSSL
	/*
	 * Scan the loopsecond table to determine the TAI offset. If
	 * there is a scheduled leap in future, set the leap warning,
	 * but only if less than 30 days before the leap.
	 */
	tpt = (u_int32 *)tai_leap.ptr;
	len = ntohl(tai_leap.vallen) / sizeof(u_int32);
	if (tpt != NULL) {
		for (i = 0; i < len; i++) {
			togo = (long)ntohl(tpt[i]) -
			    (long)peer->rec.l_ui;
			if (togo > 0) {
				if (togo < CLOCK_JUNE)
					leap_next |= LEAP_ADDSECOND;
				break;
			}
		}
#if defined(STA_NANO) && NTP_API == 4
		if (pll_control && kern_enable && sys_tai == 0) {
			memset(&ntv, 0, sizeof(ntv));
			ntv.modes = MOD_TAI;
			ntv.constant = i + TAI_1972 - 1;
			ntp_adjtime(&ntv);
		}
#endif /* STA_NANO */
		sys_tai = i + TAI_1972 - 1;
	}
#endif /* OPENSSL */
#ifdef KERNEL_PLL
	/*
	 * This code segment works when clock adjustments are made using
	 * precision time kernel support and the ntp_adjtime() system
	 * call. This support is available in Solaris 2.6 and later,
	 * Digital Unix 4.0 and later, FreeBSD, Linux and specially
	 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
	 * DECstation 5000/240 and Alpha AXP, additional kernel
	 * modifications provide a true microsecond clock and nanosecond
	 * clock, respectively.
	 *
	 * Important note: The kernel discipline is used only if the
	 * step threshold is less than 0.5 s, as anything higher can
	 * lead to overflow problems. This might occur if some misguided
	 * lad set the step threshold to something ridiculous.
	 */
	if (pll_control && kern_enable) {

		/*
		 * We initialize the structure for the ntp_adjtime()
		 * system call. We have to convert everything to
		 * microseconds or nanoseconds first. Do not update the
		 * system variables if the ext_enable flag is set. In
		 * this case, the external clock driver will update the
		 * variables, which will be read later by the local
		 * clock driver. Afterwards, remember the time and
		 * frequency offsets for jitter and stability values and
		 * to update the frequency file.
		 */
		memset(&ntv,  0, sizeof(ntv));
		if (ext_enable) {
			ntv.modes = MOD_STATUS;
		} else {
			struct tm *tm = NULL;
			time_t tstamp;

#ifdef STA_NANO
			ntv.modes = MOD_BITS | MOD_NANO;
#else /* STA_NANO */
			ntv.modes = MOD_BITS;
#endif /* STA_NANO */
			if (clock_offset < 0)
				dtemp = -.5;
			else
				dtemp = .5;
#ifdef STA_NANO
			ntv.offset = (int32)(clock_offset * 1e9 +
			    dtemp);
			ntv.constant = sys_poll;
#else /* STA_NANO */
			ntv.offset = (int32)(clock_offset * 1e6 +
			    dtemp);
			ntv.constant = sys_poll - 4;
#endif /* STA_NANO */

			/*
			 * The frequency is set directly only if
			 * clock_frequency is nonzero coming out of FREQ
			 * state.
			 */
			if (clock_frequency != 0) {
				ntv.modes |= MOD_FREQUENCY;
				ntv.freq = (int32)((clock_frequency +
				    drift_comp) * 65536e6);
			}
			ntv.esterror = (u_int32)(clock_jitter * 1e6);
			ntv.maxerror = (u_int32)((sys_rootdelay / 2 +
			    sys_rootdispersion) * 1e6);
			ntv.status = STA_PLL;

			/*
			 * Set the leap bits in the status word, but
			 * only on the last day of June or December.
			 */
			tstamp = peer->rec.l_ui - JAN_1970;
			tm = gmtime(&tstamp);
			if (tm != NULL) {
				if ((tm->tm_mon + 1 == 6 &&
				    tm->tm_mday == 30) || (tm->tm_mon +
				    1 == 12 && tm->tm_mday == 31)) {
					if (leap_next & LEAP_ADDSECOND)
						ntv.status |= STA_INS;
					else if (leap_next &
					    LEAP_DELSECOND)
						ntv.status |= STA_DEL;
				}
			}

			/*
			 * If the PPS signal is up and enabled, light
			 * the frequency bit. If the PPS driver is
			 * working, light the phase bit as well. If not,
			 * douse the lights, since somebody else may
			 * have left the switch on.
			 */
			if (pps_enable && pll_status & STA_PPSSIGNAL) {
				ntv.status |= STA_PPSFREQ;
				if (pps_stratum < STRATUM_UNSPEC)
					ntv.status |= STA_PPSTIME;
			} else {
				ntv.status &= ~(STA_PPSFREQ |
				    STA_PPSTIME);
			}
		}

		/*
		 * Pass the stuff to the kernel. If it squeals, turn off
		 * the pig. In any case, fetch the kernel offset and
		 * frequency and pretend we did it here.
		 */
		if (ntp_adjtime(&ntv) == TIME_ERROR) {
			NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT)
			    msyslog(LOG_NOTICE,
			    "kernel time sync error %04x", ntv.status);
			ntv.status &= ~(STA_PPSFREQ | STA_PPSTIME);
		}
		pll_status = ntv.status;
#ifdef STA_NANO
		clock_offset = ntv.offset / 1e9;
#else /* STA_NANO */
		clock_offset = ntv.offset / 1e6;
#endif /* STA_NANO */
		clock_frequency = ntv.freq / 65536e6;
		flladj = plladj = 0;

		/*
		 * If the kernel PPS is lit, monitor its performance.
		 */
		if (ntv.status & STA_PPSTIME) {
			pps_control = current_time;
#ifdef STA_NANO
			clock_jitter = ntv.jitter / 1e9;
#else /* STA_NANO */
			clock_jitter = ntv.jitter / 1e6;
#endif /* STA_NANO */
		}
	} else {
#endif /* KERNEL_PLL */
 
		/*
		 * We get here if the kernel discipline is not enabled.
		 * Adjust the clock frequency as the sum of the directly
		 * computed frequency (if measured) and the PLL and FLL
		 * increments.
		 */
		clock_frequency = drift_comp + clock_frequency +
		    flladj + plladj;
#ifdef KERNEL_PLL
	}
#endif /* KERNEL_PLL */

	/*
	 * Clamp the frequency within the tolerance range and calculate
	 * the frequency change since the last update.
	 */
	if (fabs(clock_frequency) > NTP_MAXFREQ)
		NLOG(NLOG_SYNCEVENT | NLOG_SYSEVENT)
		    msyslog(LOG_NOTICE,
		    "frequency error %.0f PPM exceeds tolerance %.0f PPM",
		    clock_frequency * 1e6, NTP_MAXFREQ * 1e6);
	dtemp = SQUARE(clock_frequency - drift_comp);
	if (clock_frequency > NTP_MAXFREQ)
		drift_comp = NTP_MAXFREQ;
	else if (clock_frequency < -NTP_MAXFREQ)
		drift_comp = -NTP_MAXFREQ;
	else
		drift_comp = clock_frequency;

	/*
	 * Calculate the wander as the exponentially weighted frequency
	 * differences.
	 */
	etemp = SQUARE(clock_stability);
	clock_stability = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG);

	/*
	 * Here we adjust the poll interval by comparing the current
	 * offset with the clock jitter. If the offset is less than the
	 * clock jitter times a constant, then the averaging interval is
	 * increased, otherwise it is decreased. A bit of hysteresis
	 * helps calm the dance. Works best using burst mode.
	 */
	if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) {
		tc_counter += sys_poll;
		if (tc_counter > CLOCK_LIMIT) {
			tc_counter = CLOCK_LIMIT;
			if (sys_poll < peer->maxpoll) {
				tc_counter = 0;
				sys_poll++;
			}
		}
	} else {
		tc_counter -= sys_poll << 1;
		if (tc_counter < -CLOCK_LIMIT) {
			tc_counter = -CLOCK_LIMIT;
			if (sys_poll > peer->minpoll) {
				tc_counter = 0;
				sys_poll--;
			}
		}
	}

	/*
	 * Yibbidy, yibbbidy, yibbidy; that'h all folks.
	 */
	record_loop_stats(clock_offset, drift_comp, clock_jitter,
	    clock_stability, sys_poll);
#ifdef DEBUG
	if (debug)
		printf(
		    "local_clock: mu %lu jitr %.6f freq %.3f stab %.6f poll %d count %d\n",
		    mu, clock_jitter, drift_comp * 1e6,
		    clock_stability * 1e6, sys_poll, tc_counter);
#endif /* DEBUG */
	return (rval);
#endif /* LOCKCLOCK */
}