refclock_local.c revision 285612
1 2/* 3 * refclock_local - local pseudo-clock driver 4 * 5 * wjm 17-aug-1995: add a hook for special treatment of VMS_LOCALUNIT 6 */ 7#ifdef HAVE_CONFIG_H 8#include <config.h> 9#endif 10 11#ifdef REFCLOCK 12 13#include "ntpd.h" 14#include "ntp_refclock.h" 15#include "ntp_stdlib.h" 16 17#include <stdio.h> 18#include <ctype.h> 19 20#ifdef KERNEL_PLL 21#include "ntp_syscall.h" 22#endif 23 24/* 25 * This is a hack to allow a machine to use its own system clock as a 26 * reference clock, i.e., to free-run using no outside clock discipline 27 * source. Note that the clock selection algorithm will not select this 28 * driver unless all other sources of synchronization have been lost. 29 * This is useful if you want to use NTP in an isolated environment 30 * with no radio clock or NIST modem available. Pick a machine that you 31 * figure has a good clock oscillator and configure it with this 32 * 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. However, the 40 * preferred was to do this is using orphan mode. See the documentation. 41 * 42 * A third application for this driver is when an external discipline 43 * source is available, such as the NIST "lockclock" program, which 44 * synchronizes the local clock via a telephone modem and the NIST 45 * Automated Computer Time Service (ACTS), or the Digital Time 46 * Synchronization Service (DTSS), which runs on DCE machines. In this 47 * case the stratum should be set at zero, indicating a bona fide 48 * stratum-1 source. Exercise some caution with this, since there is no 49 * easy way to telegraph via NTP that something might be wrong in the 50 * discipline source itself. In the case of DTSS, the local clock can 51 * have a rather large jitter, depending on the interval between 52 * corrections and the intrinsic frequency error of the clock 53 * oscillator. In extreme cases, this can cause clients to exceed the 54 * 128-ms slew window and drop off the NTP subnet. 55 * 56 * Fudge Factors 57 * 58 * If fudge flag1 is lit, the leap second bit is set in the peer 59 * status word. It should be set early in the day of a leap second 60 * event and set dark on the day after the event. 61 * 62 * Note the fudge time1 and time2 have been deprecated. The fudge time1 63 * was intended to apply a bias offset. This can be done using the Unix 64 * date command. The fudge time2 was intended to apply a bias frequency. 65 * This can be done using the frequency file and/or the freq 66 * configuration command. 67 */ 68/* 69 * Local interface definitions 70 */ 71#define PRECISION (-7) /* about 10 ms precision */ 72#define DESCRIPTION "Undisciplined local clock" /* WRU */ 73#define STRATUM 5 /* default stratum */ 74#define DISPERSION .01 /* default dispersion (10 ms) */ 75 76/* 77 * Imported from the timer module 78 */ 79extern u_long current_time; 80 81/* 82 * Imported from ntp_proto 83 */ 84extern s_char sys_precision; 85 86/* 87 * Function prototypes 88 */ 89static int local_start (int, struct peer *); 90static void local_poll (int, struct peer *); 91 92/* 93 * Local variables 94 */ 95static u_long poll_time; /* last time polled */ 96 97/* 98 * Transfer vector 99 */ 100struct refclock refclock_local = { 101 local_start, /* start up driver */ 102 noentry, /* shut down driver (not used) */ 103 local_poll, /* transmit poll message */ 104 noentry, /* not used (old lcl_control) */ 105 noentry, /* initialize driver (not used) */ 106 noentry, /* not used (old lcl_buginfo) */ 107 NOFLAGS /* not used */ 108}; 109 110 111/* 112 * local_start - start up the clock 113 */ 114static int 115local_start( 116 int unit, 117 struct peer *peer 118 ) 119{ 120 struct refclockproc *pp; 121 122 pp = peer->procptr; 123 124 /* 125 * Initialize miscellaneous variables 126 */ 127 peer->precision = sys_precision; 128 pp->leap = LEAP_NOTINSYNC; 129 peer->stratum = STRATUM; 130 pp->stratum = STRATUM; 131 pp->clockdesc = DESCRIPTION; 132 memcpy(&pp->refid, "LOCL", 4); 133 poll_time = current_time; 134 return (1); 135} 136 137 138/* 139 * local_poll - called by the transmit procedure 140 * 141 * LOCKCLOCK: If the kernel supports the nanokernel or microkernel 142 * system calls, the leap bits are extracted from the kernel. If there 143 * is a kernel error or the kernel leap bits are set to 11, the NTP leap 144 * bits are set to 11 and the stratum is set to infinity. Otherwise, the 145 * NTP leap bits are set to the kernel leap bits and the stratum is set 146 * as fudged. This behavior does not faithfully follow the 147 * specification, but is probably more appropriate in a multiple-server 148 * national laboratory network. 149 */ 150static void 151local_poll( 152 int unit, 153 struct peer *peer 154 ) 155{ 156#if defined(KERNEL_PLL) && defined(LOCKCLOCK) 157 struct timex ntv; 158#endif /* KERNEL_PLL LOCKCLOCK */ 159 struct refclockproc *pp; 160 161 /* 162 * Do no evil unless the house is dark or lit with our own lamp. 163 */ 164 if (!(sys_peer == NULL || sys_peer == peer)) 165 return; 166 167#if defined(VMS) && defined(VMS_LOCALUNIT) 168 if (unit == VMS_LOCALUNIT) { 169 extern void vms_local_poll(struct peer *); 170 171 vms_local_poll(peer); 172 return; 173 } 174#endif /* VMS && VMS_LOCALUNIT */ 175 176 pp = peer->procptr; 177 pp->polls++; 178 179 /* 180 * Ramble through the usual filtering and grooming code, which 181 * is essentially a no-op and included mostly for pretty 182 * billboards. We allow a one-time time adjustment using fudge 183 * time1 (s) and a continuous frequency adjustment using fudge 184 * time 2 (ppm). 185 */ 186 poll_time = current_time; 187 refclock_process_offset(pp, pp->lastrec, pp->lastrec, 0); 188 189 /* 190 * If another process is disciplining the system clock, we set 191 * the leap bits and quality indicators from the kernel. 192 */ 193#if defined(KERNEL_PLL) && defined(LOCKCLOCK) 194 memset(&ntv, 0, sizeof ntv); 195 switch (ntp_adjtime(&ntv)) { 196 case TIME_OK: 197 pp->leap = LEAP_NOWARNING; 198 peer->stratum = pp->stratum; 199 break; 200 201 case TIME_INS: 202 pp->leap = LEAP_ADDSECOND; 203 peer->stratum = pp->stratum; 204 break; 205 206 case TIME_DEL: 207 pp->leap = LEAP_DELSECOND; 208 peer->stratum = pp->stratum; 209 break; 210 211 default: 212 pp->leap = LEAP_NOTINSYNC; 213 peer->stratum = STRATUM_UNSPEC; 214 } 215 pp->disp = 0; 216 pp->jitter = 0; 217#else /* KERNEL_PLL LOCKCLOCK */ 218 if (pp->sloppyclockflag & CLK_FLAG1) 219 pp->leap = LEAP_ADDSECOND; 220 else 221 pp->leap = LEAP_NOWARNING; 222 pp->disp = DISPERSION; 223 pp->jitter = 0; 224#endif /* KERNEL_PLL LOCKCLOCK */ 225 pp->lastref = pp->lastrec; 226 refclock_receive(peer); 227} 228#else 229int refclock_local_bs; 230#endif /* REFCLOCK */ 231