dist/ntp/ntpd/refclock_local.c

   1 /*      $NetBSD: refclock_local.c,v 1.2 2003/12/04 16:23:37 drochner Exp $      */
   2
   3
   4 /*
   5  * refclock_local - local pseudo-clock driver
   6  *
   7  * wjm 17-aug-1995: add a hook for special treatment of VMS_LOCALUNIT
   8  */
   9 #ifdef HAVE_CONFIG_H
  10 #include <config.h>
  11 #endif
  12
  13 #ifdef REFCLOCK
  14
  15 #include "ntpd.h"
  16 #include "ntp_refclock.h"
  17 #include "ntp_stdlib.h"
  18
  19 #include <stdio.h>
  20 #include <ctype.h>
  21
  22 #ifdef KERNEL_PLL
  23 #include "ntp_syscall.h"
  24 #endif
  25
  26 /*
  27  * This is a hack to allow a machine to use its own system clock as a
  28  * reference clock, i.e., to free-run using no outside clock discipline
  29  * source. This is useful if you want to use NTP in an isolated
  30  * environment with no radio clock or NIST modem available. Pick a
  31  * machine that you figure has a good clock oscillator and configure it
  32  * with this driver. Set the clock using the best means available, like
  33  * eyeball-and-wristwatch. Then, point all the other machines at this
  34  * one or use broadcast (not multicast) mode to distribute time.
  35  *
  36  * Another application for this driver is if you want to use a
  37  * particular server's clock as the clock of last resort when all other
  38  * normal synchronization sources have gone away. This is especially
  39  * useful if that server has an ovenized oscillator. For this you would
  40  * configure this driver at a higher stratum (say 5) to prevent the
  41  * server's stratum from falling below that.
  42  *
  43  * A third application for this driver is when an external discipline
  44  * source is available, such as the NIST "lockclock" program, which
  45  * synchronizes the local clock via a telephone modem and the NIST
  46  * Automated Computer Time Service (ACTS), or the Digital Time
  47  * Synchronization Service (DTSS), which runs on DCE machines. In this
  48  * case the stratum should be set at zero, indicating a bona fide
  49  * stratum-1 source. Exercise some caution with this, since there is no
  50  * easy way to telegraph via NTP that something might be wrong in the
  51  * discipline source itself. In the case of DTSS, the local clock can
  52  * have a rather large jitter, depending on the interval between
  53  * corrections and the intrinsic frequency error of the clock
  54  * oscillator. In extreme cases, this can cause clients to exceed the
  55  * 128-ms slew window and drop off the NTP subnet.
  56  *
  57  * THis driver includes provisions to telegraph synchronization state
  58  * and related variables by means of kernel variables with specially
  59  * modified kernels. This is done using the ntp_adjtime() syscall.
  60  * In the cases where another protocol or device synchronizes the local
  61  * host, the data given to the kernel can be slurped up by this driver
  62  * and distributed to clients by ordinary NTP messaging.
  63  *
  64  * In the default mode the behavior of the clock selection algorithm is
  65  * modified when this driver is in use. The algorithm is designed so
  66  * that this driver will never be selected unless no other discipline
  67  * source is available. This can be overriden with the prefer keyword of
  68  * the server configuration command, in which case only this driver will
  69  * be selected for synchronization and all other discipline sources will
  70  * be ignored. This behavior is intended for use when an external
  71  * discipline source controls the system clock.
  72  *
  73  * Fudge Factors
  74  *
  75  * The stratum for this driver set at 5 by default, but it can be
  76  * changed by the fudge command and/or the ntpdc utility. The reference
  77  * ID is 127.0.0.1 by default, but can be changed using the same mechanism.
  78  * *NEVER* configure this driver to operate at a stratum which might
  79  * possibly disrupt a client with access to a bona fide primary server,
  80  * unless the local clock oscillator is reliably disciplined by another
  81  * source. *NEVER NEVER* configure a server which might devolve to an
  82  * undisciplined local clock to use multicast mode. Always remember that
  83  * an improperly configured local clock driver let loose in the Internet
  84  * can cause very serious disruption. This is why most of us who care
  85  * about good time use cryptographic authentication.
  86  *
  87  * This driver provides a mechanism to trim the local clock in both time
  88  * and frequency, as well as a way to manipulate the leap bits. The
  89  * fudge time1 parameter adjusts the time, in seconds, and the fudge
  90  * time2 parameter adjusts the frequency, in ppm. The fudge time1
  91  * parameter is additive; that is, it adds an increment to the current
  92  * time. The fudge time2 parameter directly sets the frequency.
  93  */
  94 /*
  95  * Local interface definitions
  96  */
  97 #define PRECISION       (-7)    /* about 10 ms precision */
  98 #define DESCRIPTION "Undisciplined local clock" /* WRU */
  99 #define STRATUM         5       /* default stratum */
 100 #define DISPERSION      .01     /* default dispersion (10 ms) */
 101
 102 /*
 103  * Imported from the timer module
 104  */
 105 extern u_long current_time;
 106
 107 /*
 108  * Imported from ntp_proto
 109  */
 110 extern s_char sys_precision;
 111
 112 #ifdef KERNEL_PLL
 113 /*
 114  * Imported from ntp_loopfilter
 115  */
 116 extern int pll_control;         /* kernel pll control */
 117 extern int kern_enable;         /* kernel pll enabled */
 118 extern int ext_enable;          /* external clock enable */
 119 #endif /* KERNEL_PLL */
 120
 121 /*
 122  * Function prototypes
 123  */
 124 static  int local_start P((int, struct peer *));
 125 static  void    local_poll      P((int, struct peer *));
 126
 127 /*
 128  * Local variables
 129  */
 130 static  u_long poll_time;       /* last time polled */
 131
 132 /*
 133  * Transfer vector
 134  */
 135 struct  refclock refclock_local = {
 136         local_start,            /* start up driver */
 137         noentry,                /* shut down driver (not used) */
 138         local_poll,             /* transmit poll message */
 139         noentry,                /* not used (old lcl_control) */
 140         noentry,                /* initialize driver (not used) */
 141         noentry,                /* not used (old lcl_buginfo) */
 142         NOFLAGS                 /* not used */
 143 };
 144
 145
 146 /*
 147  * local_start - start up the clock
 148  */
 149 static int
 150 local_start(
 151         int unit,
 152         struct peer *peer
 153         )
 154 {
 155         struct refclockproc *pp;
 156
 157         pp = peer->procptr;
 158
 159         /*
 160          * Initialize miscellaneous variables
 161          */
 162         peer->precision = sys_precision;
 163         pp->leap = LEAP_NOTINSYNC;
 164         peer->stratum = STRATUM;
 165         pp->stratum = STRATUM;
 166         pp->clockdesc = DESCRIPTION;
 167         memcpy(&pp->refid, "LOCL", 4);
 168         poll_time = current_time;
 169         return (1);
 170 }
 171
 172
 173 /*
 174  * local_poll - called by the transmit procedure
 175  *
 176  * LOCKCLOCK: If the kernel supports the nanokernel or microkernel
 177  * system calls, the leap bits are extracted from the kernel. If there
 178  * is a kernel error or the kernel leap bits are set to 11, the NTP leap
 179  * bits are set to 11 and the stratum is set to infinity. Otherwise, the
 180  * NTP leap bits are set to the kernel leap bits and the stratum is set
 181  * as fudged. This behavior does not faithfully follow the
 182  * specification, but is probably more appropriate in a multiple-server
 183  * national laboratory network.
 184  */
 185 static void
 186 local_poll(
 187         int unit,
 188         struct peer *peer
 189         )
 190 {
 191 #if defined(KERNEL_PLL) && defined(LOCKCLOCK)
 192         struct timex ntv;
 193 #endif /* KERNEL_PLL LOCKCLOCK */
 194         struct refclockproc *pp;
 195
 196 #if defined(VMS) && defined(VMS_LOCALUNIT)
 197         if (unit == VMS_LOCALUNIT) {
 198                 extern void vms_local_poll(struct peer *);
 199
 200                 vms_local_poll(peer);
 201                 return;
 202         }
 203 #endif /* VMS && VMS_LOCALUNIT */
 204         pp = peer->procptr;
 205         pp->polls++;
 206
 207         /*
 208          * Ramble through the usual filtering and grooming code, which
 209          * is essentially a no-op and included mostly for pretty
 210          * billboards. We allow a one-time time adjustment using fudge
 211          * time1 (s) and a continuous frequency adjustment using fudge
 212          * time 2 (ppm).
 213          */
 214         get_systime(&pp->lastrec);
 215         pp->fudgetime1 += pp->fudgetime2 * 1e-6 * (current_time -
 216             poll_time);
 217         poll_time = current_time;
 218         refclock_process_offset(pp, pp->lastrec, pp->lastrec,
 219             pp->fudgetime1);
 220
 221         /*
 222          * If another process is disciplining the system clock, we set
 223          * the leap bits and quality indicators from the kernel.
 224          */
 225 #if defined(KERNEL_PLL) && defined(LOCKCLOCK)
 226         memset(&ntv,  0, sizeof ntv);
 227         switch (ntp_adjtime(&ntv)) {
 228         case TIME_OK:
 229                 pp->leap = LEAP_NOWARNING;
 230                 peer->stratum = pp->stratum;
 231                 break;
 232
 233         case TIME_INS:
 234                 pp->leap = LEAP_ADDSECOND;
 235                 peer->stratum = pp->stratum;
 236                 break;
 237
 238         case TIME_DEL:
 239                 pp->leap = LEAP_DELSECOND;
 240                 peer->stratum = pp->stratum;
 241                 break;
 242
 243         default:
 244                 pp->leap = LEAP_NOTINSYNC;
 245                 peer->stratum = STRATUM_UNSPEC;
 246         }
 247         pp->disp = 0;
 248         pp->jitter = 0;
 249 #else /* KERNEL_PLL LOCKCLOCK */
 250         pp->leap = LEAP_NOWARNING;
 251         pp->disp = DISPERSION;
 252         pp->jitter = 0;
 253 #endif /* KERNEL_PLL LOCKCLOCK */
 254         pp->lastref = pp->lastrec;
 255         refclock_receive(peer);
 256         pp->fudgetime1 = 0;
 257 }
 258 #else
 259 int refclock_local_bs;
 260 #endif /* REFCLOCK */