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NetBSD/dist/ntp/ntpd/refclock_local.c

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/* $NetBSD: refclock_local.c,v 1.1.1.1 2000/03/29 12:38:53 simonb Exp $ */
/* wjm 17-aug-1995: add a hook for special treatment of VMS_LOCALUNIT */
/*
* refclock_local - local pseudo-clock driver
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef REFCLOCK
#include <stdio.h>
#include <ctype.h>
#include <sys/time.h>
#include "ntpd.h"
#include "ntp_refclock.h"
#include "ntp_stdlib.h"
#ifdef KERNEL_PLL
#include "ntp_syscall.h"
#endif
/*
* This is a hack to allow a machine to use its own system clock as a
* reference clock, i.e., to free-run using no outside clock discipline
* source. This is useful if you want to use NTP in an isolated
* environment with no radio clock or NIST modem available. Pick a
* machine that you figure has a good clock oscillator and configure it
* with this driver. Set the clock using the best means available, like
* eyeball-and-wristwatch. Then, point all the other machines at this
* one or use broadcast (not multicast) mode to distribute time.
*
* Another application for this driver is if you want to use a
* particular server's clock as the clock of last resort when all other
* normal synchronization sources have gone away. This is especially
* useful if that server has an ovenized oscillator. For this you would
* configure this driver at a higher stratum (say 3 or 4) to prevent the
* server's stratum from falling below that.
*
* A third application for this driver is when an external discipline
* source is available, such as the NIST "lockclock" program, which
* synchronizes the local clock via a telephone modem and the NIST
* Automated Computer Time Service (ACTS), or the Digital Time
* Synchronization Service (DTSS), which runs on DCE machines. In this
* case the stratum should be set at zero, indicating a bona fide
* stratum-1 source. Exercise some caution with this, since there is no
* easy way to telegraph via NTP that something might be wrong in the
* discipline source itself. In the case of DTSS, the local clock can
* have a rather large jitter, depending on the interval between
* corrections and the intrinsic frequency error of the clock
* oscillator. In extreme cases, this can cause clients to exceed the
* 128-ms slew window and drop off the NTP subnet.
*
* THis driver includes provisions to telegraph synchronization state
* and related variables by means of kernel variables with specially
* modified kernels. This is done using the ntp_adjtime() syscall.
* In the cases where another protocol or device synchronizes the local
* host, the data given to the kernel can be slurped up by this driver
* and distributed to clients by ordinary NTP messaging.
*
* In the default mode the behavior of the clock selection algorithm is
* modified when this driver is in use. The algorithm is designed so
* that this driver will never be selected unless no other discipline
* source is available. This can be overriden with the prefer keyword of
* the server configuration command, in which case only this driver will
* be selected for synchronization and all other discipline sources will
* be ignored. This behavior is intended for use when an external
* discipline source controls the system clock.
*
* Fudge Factors
*
* The stratum for this driver set at 3 by default, but it can be changed
* by the fudge command and/or the ntpdc utility. The reference ID is
* "LCL" by default, but can be changed using the same mechanism. *NEVER*
* configure this driver to operate at a stratum which might possibly
* disrupt a client with access to a bona fide primary server, unless the
* local clock oscillator is reliably disciplined by another source.
* *NEVER NEVER* configure a server which might devolve to an undisciplined
* local clock to use multicast mode. Always remember that an improperly
* configured local clock driver let loose in the Internet can cause
* very serious disruption. This is why most of us who care about good
* time use cryptographic authentication.
*
* This driver provides a mechanism to trim the local clock in both time
* and frequency, as well as a way to manipulate the leap bits. The
* fudge time1 parameter adjusts the time, in seconds, and the fudge
* time2 parameter adjusts the frequency, in ppm. The fudge time1 parameter
* is additive; that is, it adds an increment to the current time. The
* fudge time2 parameter directly sets the frequency.
*/
/*
* Local interface definitions
*/
#define PRECISION (-7) /* about 10 ms precision */
#define REFID "LCL\0" /* reference ID */
#define DESCRIPTION "Undisciplined local clock" /* WRU */
#define STRATUM 3 /* default stratum */
#define DISPERSION .01 /* default dispersion (10 ms) */
/*
* Imported from the timer module
*/
extern u_long current_time;
/*
* Imported from ntp_proto
*/
extern s_char sys_precision;
#ifdef KERNEL_PLL
/*
* Imported from ntp_loopfilter
*/
extern int pll_control; /* kernel pll control */
extern int kern_enable; /* kernel pll enabled */
extern int ext_enable; /* external clock enable */
#endif /* KERNEL_PLL */
/*
* Function prototypes
*/
static int local_start P((int, struct peer *));
static void local_poll P((int, struct peer *));
/*
* Local variables
*/
static u_long poll_time; /* last time polled */
/*
* Transfer vector
*/
struct refclock refclock_local = {
local_start, /* start up driver */
noentry, /* shut down driver (not used) */
local_poll, /* transmit poll message */
noentry, /* not used (old lcl_control) */
noentry, /* initialize driver (not used) */
noentry, /* not used (old lcl_buginfo) */
NOFLAGS /* not used */
};
/*
* local_start - start up the clock
*/
static int
local_start(
int unit,
struct peer *peer
)
{
struct refclockproc *pp;
pp = peer->procptr;
/*
* Initialize miscellaneous variables
*/
peer->precision = sys_precision;
peer->stratum = STRATUM;
pp->clockdesc = DESCRIPTION;
memcpy((char *)&pp->refid, REFID, 4);
#if defined(VMS) && defined(VMS_LOCALUNIT)
/* provide a non-standard REFID */
if(unit == VMS_LOCALUNIT)
memcpy((char *)&pp->refid,"LCLv",4);
#endif /* VMS && VMS_LOCALUNIT */
poll_time = current_time;
return (1);
}
/*
* local_poll - called by the transmit procedure
*/
static void
local_poll(
int unit,
struct peer *peer
)
{
struct refclockproc *pp;
#if defined(KERNEL_PLL) && defined(STA_CLK)
struct timex ntv;
int retval;
#endif /* KERNEL_PLL STA_CLK */
#if defined(VMS) && defined(VMS_LOCALUNIT)
if(unit == VMS_LOCALUNIT) {
extern void vms_local_poll(struct peer *);
vms_local_poll(peer);
return;
}
#endif /* VMS && VMS_LOCALUNIT */
pp = peer->procptr;
pp->polls++;
/*
* Ramble through the usual filtering and grooming code, which
* is essentially a no-op and included mostly for pretty
* billboards. We allow a one-time time adjustment using fudge
* time1 (s) and a continuous frequency adjustment using fudge
* time 2 (ppm).
*/
get_systime(&pp->lastrec);
pp->fudgetime1 += pp->fudgetime2 * 1e-6 * (current_time -
poll_time);
poll_time = current_time;
refclock_process_offset(pp, pp->lastrec, pp->lastrec, pp->fudgetime1);
pp->leap = LEAP_NOWARNING;
pp->disp = DISPERSION;
pp->variance = 0;
#if defined(KERNEL_PLL) && defined(STA_CLK)
/*
* If the kernel pll code is up and running, somebody else
* may come diddle the clock. If so, they better use ntp_adjtime(),
* and set the STA_CLK bit in the status word. In this case, the
* performance information is read from the kernel and becomes the
* variables presented to the clock mitigation process.
*/
if (pll_control && kern_enable && (peer->flags & FLAG_PREFER)) {
memset((char *)&ntv, 0, sizeof ntv);
retval = ntp_adjtime(&ntv);
if (ntv.status & STA_CLK) {
ext_enable = 1;
switch(retval) {
case TIME_OK:
pp->leap = LEAP_NOWARNING;
break;
case TIME_INS:
pp->leap = LEAP_ADDSECOND;
break;
case TIME_DEL:
pp->leap = LEAP_DELSECOND;
break;
case TIME_ERROR:
pp->leap = LEAP_NOTINSYNC;
}
pp->disp = ntv.maxerror / 1e6;
pp->variance = SQUARE(ntv.esterror / 1e6);
}
} else {
ext_enable = 0;
}
#endif /* KERNEL_PLL STA_CLK */
refclock_receive(peer);
pp->fudgetime1 = 0;
}
#endif /* REFCLOCK */
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