refclock_local.c revision 290000
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 * None currently supported. 59 */ 60/* 61 * Local interface definitions 62 */ 63#define PRECISION (-7) /* about 10 ms precision */ 64#define DESCRIPTION "Undisciplined local clock" /* WRU */ 65#define STRATUM 5 /* default stratum */ 66#define DISPERSION .01 /* default dispersion (10 ms) */ 67 68/* 69 * Imported from the timer module 70 */ 71extern u_long current_time; 72 73/* 74 * Imported from ntp_proto 75 */ 76extern s_char sys_precision; 77 78/* 79 * Function prototypes 80 */ 81static int local_start (int, struct peer *); 82static void local_poll (int, struct peer *); 83 84/* 85 * Local variables 86 */ 87static u_long poll_time; /* last time polled */ 88 89/* 90 * Transfer vector 91 */ 92struct refclock refclock_local = { 93 local_start, /* start up driver */ 94 noentry, /* shut down driver (not used) */ 95 local_poll, /* transmit poll message */ 96 noentry, /* not used (old lcl_control) */ 97 noentry, /* initialize driver (not used) */ 98 noentry, /* not used (old lcl_buginfo) */ 99 NOFLAGS /* not used */ 100}; 101 102 103/* 104 * local_start - start up the clock 105 */ 106static int 107local_start( 108 int unit, 109 struct peer *peer 110 ) 111{ 112 struct refclockproc *pp; 113 114 pp = peer->procptr; 115 116 /* 117 * Initialize miscellaneous variables 118 */ 119 peer->precision = sys_precision; 120 pp->leap = LEAP_NOTINSYNC; 121 peer->stratum = STRATUM; 122 pp->stratum = STRATUM; 123 pp->clockdesc = DESCRIPTION; 124 memcpy(&pp->refid, "LOCL", 4); 125 poll_time = current_time; 126 return (1); 127} 128 129 130/* 131 * local_poll - called by the transmit procedure 132 * 133 * LOCKCLOCK: If the kernel supports the nanokernel or microkernel 134 * system calls, the leap bits are extracted from the kernel. If there 135 * is a kernel error or the kernel leap bits are set to 11, the NTP leap 136 * bits are set to 11 and the stratum is set to infinity. Otherwise, the 137 * NTP leap bits are set to the kernel leap bits and the stratum is set 138 * as fudged. This behavior does not faithfully follow the 139 * specification, but is probably more appropriate in a multiple-server 140 * national laboratory network. 141 */ 142static void 143local_poll( 144 int unit, 145 struct peer *peer 146 ) 147{ 148#if defined(KERNEL_PLL) && defined(LOCKCLOCK) 149 struct timex ntv; 150#endif /* KERNEL_PLL LOCKCLOCK */ 151 struct refclockproc *pp; 152 153 /* 154 * Do no evil unless the house is dark or lit with our own lamp. 155 */ 156 if (!(sys_peer == NULL || sys_peer == peer)) 157 return; 158 159#if defined(VMS) && defined(VMS_LOCALUNIT) 160 if (unit == VMS_LOCALUNIT) { 161 extern void vms_local_poll(struct peer *); 162 163 vms_local_poll(peer); 164 return; 165 } 166#endif /* VMS && VMS_LOCALUNIT */ 167 168 pp = peer->procptr; 169 pp->polls++; 170 171 /* 172 * Ramble through the usual filtering and grooming code, which 173 * is essentially a no-op and included mostly for pretty 174 * billboards. 175 */ 176 poll_time = current_time; 177 refclock_process_offset(pp, pp->lastrec, pp->lastrec, 0); 178 179 /* 180 * If another process is disciplining the system clock, we set 181 * the leap bits and quality indicators from the kernel. 182 */ 183#if defined(KERNEL_PLL) && defined(LOCKCLOCK) 184 memset(&ntv, 0, sizeof ntv); 185 switch (ntp_adjtime(&ntv)) { 186 case TIME_OK: 187 pp->leap = LEAP_NOWARNING; 188 peer->stratum = pp->stratum; 189 break; 190 191 case TIME_INS: 192 pp->leap = LEAP_ADDSECOND; 193 peer->stratum = pp->stratum; 194 break; 195 196 case TIME_DEL: 197 pp->leap = LEAP_DELSECOND; 198 peer->stratum = pp->stratum; 199 break; 200 201 default: 202 pp->leap = LEAP_NOTINSYNC; 203 peer->stratum = STRATUM_UNSPEC; 204 } 205 pp->disp = 0; 206 pp->jitter = 0; 207#else /* KERNEL_PLL LOCKCLOCK */ 208 pp->disp = DISPERSION; 209 pp->jitter = 0; 210#endif /* KERNEL_PLL LOCKCLOCK */ 211 pp->lastref = pp->lastrec; 212 refclock_receive(peer); 213} 214#else 215int refclock_local_bs; 216#endif /* REFCLOCK */ 217