/* * 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 #ifdef REFCLOCK #include "ntpd.h" #include "ntp_refclock.h" #include "ntp_stdlib.h" #include <stdio.h> #include <ctype.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 5) 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 5 by default, but it can be * changed by the fudge command and/or the ntpdc utility. The reference * ID is 127.0.0.1 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 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; #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; pp->leap = LEAP_NOTINSYNC; peer->stratum = STRATUM; pp->stratum = STRATUM; pp->clockdesc = DESCRIPTION; memcpy(&pp->refid, "LOCL", 4); poll_time = current_time; return (1); } /* * 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; #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); /* * 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; default: pp->leap = LEAP_NOTINSYNC; peer->stratum = STRATUM_UNSPEC; } pp->disp = 0; pp->jitter = 0; #else /* KERNEL_PLL LOCKCLOCK */ pp->leap = LEAP_NOWARNING; pp->disp = DISPERSION; pp->jitter = 0; #endif /* KERNEL_PLL LOCKCLOCK */ pp->lastref = pp->lastrec; refclock_receive(peer); pp->fudgetime1 = 0; } #else int refclock_local_bs; #endif /* REFCLOCK */