correct.c revision 216372 
1/*-
2 * Copyright (c) 1985, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#ifndef lint
31#if 0
32static char sccsid[] = "@(#)correct.c	8.1 (Berkeley) 6/6/93";
33#endif
34static const char rcsid[] =
35  "$FreeBSD: head/usr.sbin/timed/timed/correct.c 216372 2010-12-11 09:38:12Z joel $";
36#endif /* not lint */
37
38#include "globals.h"
39#include <math.h>
40#include <sys/types.h>
41#include <sys/times.h>
42
43static void adjclock(struct timeval *);
44
45/*
46 * sends to the slaves the corrections for their clocks after fixing our
47 * own
48 */
49void
50correct(avdelta)
51	long avdelta;
52{
53	struct hosttbl *htp;
54	int corr;
55	struct timeval adjlocal, tmptv;
56	struct tsp to;
57	struct tsp *answer;
58
59	mstotvround(&adjlocal, avdelta);
60
61	for (htp = self.l_fwd; htp != &self; htp = htp->l_fwd) {
62		if (htp->delta != HOSTDOWN)  {
63			corr = avdelta - htp->delta;
64/* If the other machine is off in the weeds, set its time directly.
65 *	If a slave gets the wrong day, the original code would simply
66 *	fix the minutes.  If you fix a network partition, you can get
67 *	into such situations.
68 */
69			if (htp->need_set
70			    || corr >= MAXADJ*1000
71			    || corr <= -MAXADJ*1000) {
72				htp->need_set = 0;
73				(void)gettimeofday(&tmptv,0);
74				timevaladd(&tmptv, &adjlocal);
75				to.tsp_time.tv_sec = tmptv.tv_sec;
76				to.tsp_time.tv_usec = tmptv.tv_usec;
77				to.tsp_type = TSP_SETTIME;
78			} else {
79				tmptv.tv_sec = to.tsp_time.tv_sec;
80				tmptv.tv_usec = to.tsp_time.tv_usec;
81				mstotvround(&tmptv, corr);
82				to.tsp_time.tv_sec = tmptv.tv_sec;
83				to.tsp_time.tv_usec = tmptv.tv_usec;
84				to.tsp_type = TSP_ADJTIME;
85			}
86			(void)strcpy(to.tsp_name, hostname);
87			answer = acksend(&to, &htp->addr, htp->name,
88					 TSP_ACK, 0, 0);
89			if (!answer) {
90				htp->delta = HOSTDOWN;
91				syslog(LOG_WARNING,
92				       "no reply to time correction from %s",
93				       htp->name);
94				if (++htp->noanswer >= LOSTHOST) {
95					if (trace) {
96						fprintf(fd,
97					     "purging %s for not answering\n",
98							htp->name);
99						(void)fflush(fd);
100					}
101					htp = remmach(htp);
102				}
103			}
104		}
105	}
106
107	/*
108	 * adjust our own clock now that we are not sending it out
109	 */
110	adjclock(&adjlocal);
111}
112
113
114static void
115adjclock(corr)
116	struct timeval *corr;
117{
118	static int passes = 0;
119	static int smoother = 0;
120	long delta;			/* adjustment in usec */
121	long ndelta;
122	struct timeval now;
123	struct timeval adj;
124
125	if (!timerisset(corr))
126		return;
127
128	adj = *corr;
129	if (adj.tv_sec < MAXADJ && adj.tv_sec > - MAXADJ) {
130		delta = adj.tv_sec*1000000 + adj.tv_usec;
131		/* If the correction is less than the minimum round
132		 *	trip time for an ICMP packet, and thus
133		 *	less than the likely error in the measurement,
134		 *	do not do the entire correction.  Do half
135		 *	or a quarter of it.
136		 */
137
138		if (delta > -MIN_ROUND*1000
139		    && delta < MIN_ROUND*1000) {
140			if (smoother <= 4)
141				smoother++;
142			ndelta = delta >> smoother;
143			if (trace)
144				fprintf(fd,
145					"trimming delta %ld usec to %ld\n",
146					delta, ndelta);
147			adj.tv_usec = ndelta;
148			adj.tv_sec = 0;
149		} else if (smoother > 0) {
150			smoother--;
151		}
152		if (0 > adjtime(corr, 0)) {
153			syslog(LOG_ERR, "adjtime: %m");
154		}
155		if (passes > 1
156		    && (delta < -BIG_ADJ || delta > BIG_ADJ)) {
157			smoother = 0;
158			passes = 0;
159			syslog(LOG_WARNING,
160			       "large time adjustment of %+.3f sec",
161			       delta/1000000.0);
162		}
163	} else {
164		syslog(LOG_WARNING,
165		       "clock correction %ld sec too large to adjust",
166		       adj.tv_sec);
167		(void) gettimeofday(&now, 0);
168		timevaladd(&now, corr);
169		if (settimeofday(&now, 0) < 0)
170			syslog(LOG_ERR, "settimeofday: %m");
171	}
172}
173
174
175/* adjust the time in a message by the time it
176 *	spent in the queue
177 */
178void
179adj_msg_time(msg, now)
180	struct tsp *msg;
181	struct timeval *now;
182{
183	msg->tsp_time.tv_sec += (now->tv_sec - from_when.tv_sec);
184	msg->tsp_time.tv_usec += (now->tv_usec - from_when.tv_usec);
185
186	while (msg->tsp_time.tv_usec < 0) {
187		msg->tsp_time.tv_sec--;
188		msg->tsp_time.tv_usec += 1000000;
189	}
190	while (msg->tsp_time.tv_usec >= 1000000) {
191		msg->tsp_time.tv_sec++;
192		msg->tsp_time.tv_usec -= 1000000;
193	}
194}
195