/*
* refclock_local - local pseudo-clock driver
*
* wjm 17-aug-1995: add a hook for special treatment of VMS_LOCALUNIT
*/
#ifdef HAVE_CONFIG_H
#include <config.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. Note that the clock selection algorithm will not select this
* driver unless all other sources of synchronization have been lost.
* 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. However, the
* preferred was to do this is using orphan mode. See the documentation.
*
* 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.
*
* Fudge Factors
*
* None currently supported.
*/
/*
* Local interface definitions
*/
#define PRECISION (-7) /* about 10 ms precision */
#define DESCRIPTION "Undisciplined local clock" /* WRU */
#define STRATUM 5 /* 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;
/*
* Function prototypes
*/
static int local_start (int, struct peer *);
static void local_poll (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;
/*
* local_poll - called by the transmit procedure
*
* LOCKCLOCK: If the kernel supports the nanokernel or microkernel
* system calls, the leap bits are extracted from the kernel. If there
* is a kernel error or the kernel leap bits are set to 11, the NTP leap
* bits are set to 11 and the stratum is set to infinity. Otherwise, the
* NTP leap bits are set to the kernel leap bits and the stratum is set
* as fudged. This behavior does not faithfully follow the
* specification, but is probably more appropriate in a multiple-server
* national laboratory network.
*/
static void
local_poll(
int unit,
struct peer *peer
)
{
#if defined(KERNEL_PLL) && defined(LOCKCLOCK)
struct timex ntv;
#endif /* KERNEL_PLL LOCKCLOCK */
struct refclockproc *pp;
/*
* Do no evil unless the house is dark or lit with our own lamp.
*/
if (!(sys_peer == NULL || sys_peer == peer))
return;
/*
* Ramble through the usual filtering and grooming code, which
* is essentially a no-op and included mostly for pretty
* billboards.
*/
poll_time = current_time;
refclock_process_offset(pp, pp->lastrec, pp->lastrec, 0);
/*
* If another process is disciplining the system clock, we set
* the leap bits and quality indicators from the kernel.
*/
#if defined(KERNEL_PLL) && defined(LOCKCLOCK)
memset(&ntv, 0, sizeof ntv);
switch (ntp_adjtime(&ntv)) {
case TIME_OK:
pp->leap = LEAP_NOWARNING;
peer->stratum = pp->stratum;
break;
case TIME_INS:
pp->leap = LEAP_ADDSECOND;
peer->stratum = pp->stratum;
break;
case TIME_DEL:
pp->leap = LEAP_DELSECOND;
peer->stratum = pp->stratum;
break;
