ntp_refclock.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

/*
 * ntp_refclock - processing support for reference clocks
 */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include "ntpd.h"
#include "ntp_io.h"
#include "ntp_unixtime.h"
#include "ntp_tty.h"
#include "ntp_refclock.h"
#include "ntp_stdlib.h"

#include <stdio.h>

#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif /* HAVE_SYS_IOCTL_H */

#ifdef REFCLOCK

#ifdef TTYCLK
# ifdef HAVE_SYS_CLKDEFS_H
#  include <sys/clkdefs.h>
#  include <stropts.h>
# endif
# ifdef HAVE_SYS_SIO_H
#  include <sys/sio.h>
# endif
#endif /* TTYCLK */

#ifdef KERNEL_PLL
#include "ntp_syscall.h"
#endif /* KERNEL_PLL */

/*
 * Reference clock support is provided here by maintaining the fiction
 * that the clock is actually a peer. As no packets are exchanged with a
 * reference clock, however, we replace the transmit, receive and packet
 * procedures with separate code to simulate them. Routines
 * refclock_transmit() and refclock_receive() maintain the peer
 * variables in a state analogous to an actual peer and pass reference
 * clock data on through the filters. Routines refclock_peer() and
 * refclock_unpeer() are called to initialize and terminate reference
 * clock associations. A set of utility routines is included to open
 * serial devices, process sample data, edit input lines to extract
 * embedded timestamps and to peform various debugging functions.
 *
 * The main interface used by these routines is the refclockproc
 * structure, which contains for most drivers the decimal equivalants of
 * the year, day, month, hour, second and millisecond/microsecond
 * decoded from the ASCII timecode. Additional information includes the
 * receive timestamp, exception report, statistics tallies, etc. In
 * addition, there may be a driver-specific unit structure used for
 * local control of the device.
 *
 * The support routines are passed a pointer to the peer structure,
 * which is used for all peer-specific processing and contains a pointer
 * to the refclockproc structure, which in turn containes a pointer to
 * the unit structure, if used. The peer structure is identified by an
 * interface address in the dotted quad form 127.127.t.u (for now only
 * IPv4 addresses are used, so we need to be sure the address is it),
 * where t is the clock type and u the unit. Some legacy drivers derive
 * the refclockproc structure pointer from the table
 * typeunit[type][unit]. This interface is strongly discouraged and may
 * be abandoned in future.
 */
#define MAXUNIT 	4	/* max units */
#define FUDGEFAC	.1	/* fudge correction factor */
#define LF		0x0a	/* ASCII LF */

#ifdef PPS
int	fdpps;			/* ppsclock legacy */
#endif /* PPS */
int	cal_enable;		/* enable refclock calibrate */

/*
 * Type/unit peer index. Used to find the peer structure for control and
 * debugging. When all clock drivers have been converted to new style,
 * this dissapears.
 */
static struct peer *typeunit[REFCLK_MAX + 1][MAXUNIT];

/*
 * Forward declarations
 */
#ifdef QSORT_USES_VOID_P
static int refclock_cmpl_fp P((const void *, const void *));
#else
static int refclock_cmpl_fp P((const double *, const double *));
#endif /* QSORT_USES_VOID_P */
static int refclock_sample P((struct refclockproc *));


/*
 * refclock_report - note the occurance of an event
 *
 * This routine presently just remembers the report and logs it, but
 * does nothing heroic for the trap handler. It tries to be a good
 * citizen and bothers the system log only if things change.
 */
void
refclock_report(
	struct peer *peer,
	int code
	)
{
	struct refclockproc *pp;

	pp = peer->procptr;
	if (pp == NULL)
		return;

	switch (code) {
		case CEVNT_NOMINAL:
			break;

		case CEVNT_TIMEOUT:
			pp->noreply++;
			break;

		case CEVNT_BADREPLY:
			pp->badformat++;
			break;

		case CEVNT_FAULT:
			break;

		case CEVNT_PROP:
			break;

		case CEVNT_BADDATE:
		case CEVNT_BADTIME:
			pp->baddata++;
			break;

		default:
			/* shouldn't happen */
			break;
	}

	if (pp->currentstatus != code) {
		pp->currentstatus = (u_char)code;

		/* RFC1305: copy only iff not CEVNT_NOMINAL */
		if (code != CEVNT_NOMINAL)
			pp->lastevent = (u_char)code;

		if (code == CEVNT_FAULT)
			msyslog(LOG_ERR,
			    "clock %s event '%s' (0x%02x)",
			    refnumtoa(&peer->srcadr),
			    ceventstr(code), code);
		else {
			NLOG(NLOG_CLOCKEVENT)
			  msyslog(LOG_INFO,
			    "clock %s event '%s' (0x%02x)",
			    refnumtoa(&peer->srcadr),
			    ceventstr(code), code);
		}

		/* RFC1305: post peer clock event */
		report_event(EVNT_PEERCLOCK, peer);
	}
}

/*
 * init_refclock - initialize the reference clock drivers
 *
 * This routine calls each of the drivers in turn to initialize internal
 * variables, if necessary. Most drivers have nothing to say at this
 * point.
 */
void
init_refclock(void)
{
	int i, j;

	for (i = 0; i < (int)num_refclock_conf; i++) {
		if (refclock_conf[i]->clock_init != noentry)
			(refclock_conf[i]->clock_init)();
		for (j = 0; j < MAXUNIT; j++)
			typeunit[i][j] = 0;
	}
}


/*
 * refclock_newpeer - initialize and start a reference clock
 *
 * This routine allocates and initializes the interface structure which
 * supports a reference clock in the form of an ordinary NTP peer. A
 * driver-specific support routine completes the initialization, if
 * used. Default peer variables which identify the clock and establish
 * its reference ID and stratum are set here. It returns one if success
 * and zero if the clock address is invalid or already running,
 * insufficient resources are available or the driver declares a bum
 * rap.
 */
int
refclock_newpeer(
	struct peer *peer	/* peer structure pointer */
	)
{
	struct refclockproc *pp;
	u_char clktype;
	int unit;

	/*
	 * Check for valid clock address. If already running, shut it
	 * down first.
	 */
	if (peer->srcadr.ss_family != AF_INET) {
		msyslog(LOG_ERR,
		       "refclock_newpeer: clock address %s invalid, address family not implemented for refclock",
                        stoa(&peer->srcadr));
                return (0);
        }
	if (!ISREFCLOCKADR(&peer->srcadr)) {
		msyslog(LOG_ERR,
			"refclock_newpeer: clock address %s invalid",
			stoa(&peer->srcadr));
		return (0);
	}
	clktype = (u_char)REFCLOCKTYPE(&peer->srcadr);
	unit = REFCLOCKUNIT(&peer->srcadr);
	if (clktype >= num_refclock_conf || unit >= MAXUNIT ||
		refclock_conf[clktype]->clock_start == noentry) {
		msyslog(LOG_ERR,
			"refclock_newpeer: clock type %d invalid\n",
			clktype);
		return (0);
	}

	/*
	 * Allocate and initialize interface structure
	 */
	pp = (struct refclockproc *)emalloc(sizeof(struct refclockproc));
	if (pp == NULL)
		return (0);

	memset((char *)pp, 0, sizeof(struct refclockproc));
	typeunit[clktype][unit] = peer;
	peer->procptr = pp;

	/*
	 * Initialize structures
	 */
	peer->refclktype = clktype;
	peer->refclkunit = (u_char)unit;
	peer->flags |= FLAG_REFCLOCK | FLAG_FIXPOLL;
	peer->leap = LEAP_NOTINSYNC;
	peer->stratum = STRATUM_REFCLOCK;
	peer->ppoll = peer->maxpoll;
	pp->type = clktype;
	pp->timestarted = current_time;

	/*
	 * Set peer.pmode based on the hmode. For appearances only.
	 */
	switch (peer->hmode) {
	case MODE_ACTIVE:
		peer->pmode = MODE_PASSIVE;
		break;

	default:
		peer->pmode = MODE_SERVER;
		break;
	}

	/*
	 * Do driver dependent initialization. The above defaults
	 * can be wiggled, then finish up for consistency.
	 */
	if (!((refclock_conf[clktype]->clock_start)(unit, peer))) {
		refclock_unpeer(peer);
		return (0);
	}
	peer->refid = pp->refid;
	return (1);
}


/*
 * refclock_unpeer - shut down a clock
 */
void
refclock_unpeer(
	struct peer *peer	/* peer structure pointer */
	)
{
	u_char clktype;
	int unit;

	/*
	 * Wiggle the driver to release its resources, then give back
	 * the interface structure.
	 */
	if (!peer->procptr)
		return;

	clktype = peer->refclktype;
	unit = peer->refclkunit;
	if (refclock_conf[clktype]->clock_shutdown != noentry)
		(refclock_conf[clktype]->clock_shutdown)(unit, peer);
	free(peer->procptr);
	peer->procptr = 0;
}


/*
 * refclock_timer - called once per second for housekeeping.
 */
void
refclock_timer(
	struct peer *peer	/* peer structure pointer */
	)
{
	u_char clktype;
	int unit;

	clktype = peer->refclktype;
	unit = peer->refclkunit;
	if (refclock_conf[clktype]->clock_timer != noentry)
		(refclock_conf[clktype]->clock_timer)(unit, peer);
}
	

/*
 * refclock_transmit - simulate the transmit procedure
 *
 * This routine implements the NTP transmit procedure for a reference
 * clock. This provides a mechanism to call the driver at the NTP poll
 * interval, as well as provides a reachability mechanism to detect a
 * broken radio or other madness.
 */
void
refclock_transmit(
	struct peer *peer	/* peer structure pointer */
	)
{
	u_char clktype;
	int unit;

	clktype = peer->refclktype;
	unit = peer->refclkunit;
	peer->sent++;
	get_systime(&peer->xmt);

	/*
	 * This is a ripoff of the peer transmit routine, but
	 * specialized for reference clocks. We do a little less
	 * protocol here and call the driver-specific transmit routine.
	 */
	if (peer->burst == 0) {
		u_char oreach;
#ifdef DEBUG
		if (debug)
			printf("refclock_transmit: at %ld %s\n",
			    current_time, stoa(&(peer->srcadr)));
#endif

		/*
		 * Update reachability and poll variables like the
		 * network code.
		 */
		oreach = peer->reach;
		peer->reach <<= 1;
		peer->outdate = current_time;
		if (!peer->reach) {
			if (oreach) {
				report_event(EVNT_UNREACH, peer);
				peer->timereachable = current_time;
			}
		} else {
			if (!(oreach & 0x07)) {
				clock_filter(peer, 0., 0., MAXDISPERSE);
				clock_select();
			}
			if (peer->flags & FLAG_BURST)
				peer->burst = NSTAGE;
		}
	} else {
		peer->burst--;
	}
	if (refclock_conf[clktype]->clock_poll != noentry)
		(refclock_conf[clktype]->clock_poll)(unit, peer);
	poll_update(peer, peer->hpoll);
}


/*
 * Compare two doubles - used with qsort()
 */
#ifdef QSORT_USES_VOID_P
static int
refclock_cmpl_fp(
	const void *p1,
	const void *p2
	)
{
	const double *dp1 = (const double *)p1;
	const double *dp2 = (const double *)p2;

	if (*dp1 < *dp2)
		return (-1);

	if (*dp1 > *dp2)
		return (1);

	return (0);
}

#else
static int
refclock_cmpl_fp(
	const double *dp1,
	const double *dp2
	)
{
	if (*dp1 < *dp2)
		return (-1);

	if (*dp1 > *dp2)
		return (1);

	return (0);
}
#endif /* QSORT_USES_VOID_P */


/*
 * refclock_process_offset - update median filter
 *
 * This routine uses the given offset and timestamps to construct a new
 * entry in the median filter circular buffer. Samples that overflow the
 * filter are quietly discarded.
 */
void
refclock_process_offset(
	struct refclockproc *pp,	/* refclock structure pointer */
	l_fp lasttim,			/* last timecode timestamp */
	l_fp lastrec,			/* last receive timestamp */
	double fudge
	)
{
	l_fp lftemp;
	double doffset;

	pp->lastrec = lastrec;
	lftemp = lasttim;
	L_SUB(&lftemp, &lastrec);
	LFPTOD(&lftemp, doffset);
	SAMPLE(doffset + fudge);
}


/*
 * refclock_process - process a sample from the clock
 *
 * This routine converts the timecode in the form days, hours, minutes,
 * seconds and milliseconds/microseconds to internal timestamp format,
 * then constructs a new entry in the median filter circular buffer.
 * Return success (1) if the data are correct and consistent with the
 * converntional calendar.
 *
 * Important for PPS users: Normally, the pp->lastrec is set to the
 * system time when the on-time character is received and the pp->year,
 * ..., pp->second decoded and the seconds fraction pp->nsec in
 * nanoseconds). When a PPS offset is available, pp->nsec is forced to
 * zero and the fraction for pp->lastrec is set to the PPS offset.
 */
int
refclock_process(
	struct refclockproc *pp		/* refclock structure pointer */
	)
{
	l_fp offset, ltemp;

	/*
	 * Compute the timecode timestamp from the days, hours, minutes,
	 * seconds and milliseconds/microseconds of the timecode. Use
	 * clocktime() for the aggregate seconds and the msec/usec for
	 * the fraction, when present. Note that this code relies on the
	 * filesystem time for the years and does not use the years of
	 * the timecode.
	 */
	if (!clocktime(pp->day, pp->hour, pp->minute, pp->second, GMT,
		pp->lastrec.l_ui, &pp->yearstart, &offset.l_ui))
		return (0);

	offset.l_uf = 0;
	DTOLFP(pp->nsec / 1e9, &ltemp);
	L_ADD(&offset, &ltemp);
	refclock_process_offset(pp, offset, pp->lastrec,
	    pp->fudgetime1);
	return (1);
}


/*
 * refclock_sample - process a pile of samples from the clock
 *
 * This routine implements a recursive median filter to suppress spikes
 * in the data, as well as determine a performance statistic. It
 * calculates the mean offset and RMS jitter. A time adjustment
 * fudgetime1 can be added to the final offset to compensate for various
 * systematic errors. The routine returns the number of samples
 * processed, which could be zero.
 */
static int
refclock_sample(
	struct refclockproc *pp		/* refclock structure pointer */
	)
{
	int	i, j, k, m, n;
	double	off[MAXSTAGE];
	double	offset;

	/*
	 * Copy the raw offsets and sort into ascending order. Don't do
	 * anything if the buffer is empty.
	 */
	n = 0;
	while (pp->codeproc != pp->coderecv) {
		pp->codeproc = (pp->codeproc + 1) % MAXSTAGE;
		off[n] = pp->filter[pp->codeproc];
		n++;
	}
	if (n == 0)
		return (0);

	if (n > 1)
		qsort(
#ifdef QSORT_USES_VOID_P
		    (void *)
#else
		    (char *)
#endif
		    off, (size_t)n, sizeof(double), refclock_cmpl_fp);

	/*
	 * Reject the furthest from the median of the samples until
	 * approximately 60 percent of the samples remain.
	 */
	i = 0; j = n;
	m = n - (n * 4) / 10;
	while ((j - i) > m) {
		offset = off[(j + i) / 2];
		if (off[j - 1] - offset < offset - off[i])
			i++;	/* reject low end */
		else
			j--;	/* reject high end */
	}

	/*
	 * Determine the offset and jitter.
	 */
	pp->offset = 0;
	pp->jitter = 0;
	for (k = i; k < j; k++) {
		pp->offset += off[k];
		if (k > i)
			pp->jitter += SQUARE(off[k] - off[k - 1]);
	}
	pp->offset /= m;
	pp->jitter = max(SQRT(pp->jitter / m), LOGTOD(sys_precision));
#ifdef DEBUG
	if (debug)
		printf(
		    "refclock_sample: n %d offset %.6f disp %.6f jitter %.6f\n",
		    n, pp->offset, pp->disp, pp->jitter);
#endif
	return (n);
}


/*
 * refclock_receive - simulate the receive and packet procedures
 *
 * This routine simulates the NTP receive and packet procedures for a
 * reference clock. This provides a mechanism in which the ordinary NTP
 * filter, selection and combining algorithms can be used to suppress
 * misbehaving radios and to mitigate between them when more than one is
 * available for backup.
 */
void
refclock_receive(
	struct peer *peer	/* peer structure pointer */
	)
{
	struct refclockproc *pp;

#ifdef DEBUG
	if (debug)
		printf("refclock_receive: at %lu %s\n",
		    current_time, stoa(&peer->srcadr));
#endif

	/*
	 * Do a little sanity dance and update the peer structure. Groom
	 * the median filter samples and give the data to the clock
	 * filter.
	 */
	pp = peer->procptr;
	peer->leap = pp->leap;
	if (peer->leap == LEAP_NOTINSYNC)
		return;

	peer->received++;
	peer->timereceived = current_time;
	if (!peer->reach) {
		report_event(EVNT_REACH, peer);