Annotation of embedaddon/ntp/ntpd/refclock_local.c, revision 1.1.1.1
1.1 misho 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: */
79: extern u_long current_time;
80:
81: /*
82: * Imported from ntp_proto
83: */
84: extern s_char sys_precision;
85:
86: /*
87: * Function prototypes
88: */
89: static int local_start (int, struct peer *);
90: static void local_poll (int, struct peer *);
91:
92: /*
93: * Local variables
94: */
95: static u_long poll_time; /* last time polled */
96:
97: /*
98: * Transfer vector
99: */
100: struct 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: */
114: static int
115: local_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: */
150: static void
151: local_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
229: int refclock_local_bs;
230: #endif /* REFCLOCK */
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