use clock_gettime(CLOCK_MONOTONIC, ..) to get a monotonically increasing

time, and make ntpd use that to send the next uery to an ntp peer and the
like. this has the advantage that changes to the clock do not interfere
with the intervals. for example, when we start on machines without an
RTC and the initial settime (-s) kicks in, intervals were strange.
idea from amandal@entrisphere.com, this implementation by me
tested ckuethe, phessler, mbalmer, ok mbalmer

src/usr.sbin/ntpd/client.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.73 2006/10/21 07:32:46 henning Exp $ */
+/*	$OpenBSD: client.c,v 1.74 2006/10/27 12:22:41 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -32,14 +32,14 @@ void	set_deadline(struct ntp_peer *, time_t);
 void
 set_next(struct ntp_peer *p, time_t t)
 {
-	p->next = time(NULL) + t;
+	p->next = getmonotime() + t;
 	p->deadline = 0;
 }
 
 void
 set_deadline(struct ntp_peer *p, time_t t)
 {
-	p->deadline = time(NULL) + t;
+	p->deadline = getmonotime() + t;
 	p->next = 0;
 }
 
@@ -247,7 +247,7 @@ client_dispatch(struct ntp_peer *p, u_int8_t settime)
 		return (0);
 	}
 	p->reply[p->shift].error = (T2 - T1) - (T3 - T4);
-	p->reply[p->shift].rcvd = time(NULL);
+	p->reply[p->shift].rcvd = getmonotime();
 	p->reply[p->shift].good = 1;
 
 	p->reply[p->shift].status.leap = (msg.status & LIMASK);

src/usr.sbin/ntpd/ntp.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.93 2006/10/24 12:23:39 henning Exp $ */
+/*	$OpenBSD: ntp.c,v 1.94 2006/10/27 12:22:41 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -201,7 +201,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 
 		bzero(pfd, sizeof(struct pollfd) * pfd_elms);
 		bzero(idx2peer, sizeof(void *) * idx2peer_elms);
-		nextaction = time(NULL) + 3600;
+		nextaction = getmonotime() + 3600;
 		pfd[PFD_PIPE_MAIN].fd = ibuf_main->fd;
 		pfd[PFD_PIPE_MAIN].events = POLLIN;
 		pfd[PFD_HOTPLUG].fd = hotplugfd;
@@ -217,7 +217,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 		idx_peers = i;
 		sent_cnt = trial_cnt = 0;
 		TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
-			if (p->next > 0 && p->next <= time(NULL)) {
+			if (p->next > 0 && p->next <= getmonotime()) {
 				if (p->state > STATE_DNS_INPROGRESS)
 					trial_cnt++;
 				if (client_query(p) == 0)
@@ -228,7 +228,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 
 			if (p->deadline > 0 && p->deadline < nextaction)
 				nextaction = p->deadline;
-			if (p->deadline > 0 && p->deadline <= time(NULL)) {
+			if (p->deadline > 0 && p->deadline <= getmonotime()) {
 				timeout = error_interval();
 				log_debug("no reply from %s received in time, "
 				    "next query %ds", log_sockaddr(
@@ -251,9 +251,9 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 			}
 		}
 
-		if (last_sensor_scan + SENSOR_SCAN_INTERVAL < time(NULL)) {
+		if (last_sensor_scan + SENSOR_SCAN_INTERVAL < getmonotime()) {
 			sensor_scan();
-			last_sensor_scan = time(NULL);
+			last_sensor_scan = getmonotime();
 		}
 		sensors_cnt = 0;
 		TAILQ_FOREACH(s, &conf->ntp_sensors, entry) {
@@ -270,7 +270,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 		if (ibuf_main->w.queued > 0)
 			pfd[PFD_PIPE_MAIN].events |= POLLOUT;
 
-		timeout = nextaction - time(NULL);
+		timeout = nextaction - getmonotime();
 		if (timeout < 0)
 			timeout = 0;
 
@@ -315,7 +315,7 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *nconf)
 		for (s = TAILQ_FIRST(&conf->ntp_sensors); s != NULL;
 		    s = next_s) {
 			next_s = TAILQ_NEXT(s, entry);
-			if (s->next <= time(NULL))
+			if (s->next <= getmonotime())
 				sensor_query(s);
 		}
 	}

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.77 2006/10/24 12:23:39 henning Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.78 2006/10/27 12:22:41 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -297,6 +297,7 @@ void	set_next(struct ntp_peer *, time_t);
 double			gettime_corrected(void);
 double			getoffset(void);
 double			gettime(void);
+time_t			getmonotime(void);
 void			d_to_tv(double, struct timeval *);
 double			lfp_to_d(struct l_fixedpt);
 struct l_fixedpt	d_to_lfp(double);

src/usr.sbin/ntpd/sensors.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: sensors.c,v 1.24 2006/10/24 12:23:39 henning Exp $ */
+/*	$OpenBSD: sensors.c,v 1.25 2006/10/27 12:22:41 henning Exp $ */
 
 /*
  * Copyright (c) 2006 Henning Brauer <henning@openbsd.org>
@@ -101,7 +101,7 @@ sensor_add(struct sensor *sensor)
 	if ((s = calloc(1, sizeof(*s))) == NULL)
 		fatal("sensor_add calloc");
 
-	s->next = time(NULL);
+	s->next = getmonotime();
 	s->weight = cs->weight;
 	if ((s->device = strdup(sensor->device)) == NULL)
 		fatal("sensor_add strdup");
@@ -128,7 +128,9 @@ sensor_query(struct ntp_sensor *s)
 	int		 mib[3];
 	size_t		 len;
 
-	s->next = time(NULL) + SENSOR_QUERY_INTERVAL;
+	s->next = getmonotime() + SENSOR_QUERY_INTERVAL;
+
+	/* rcvd is walltime here, monotime in client.c. not used elsewhere */
 	if (s->update.rcvd < time(NULL) - SENSOR_DATA_MAXAGE)
 		s->update.good = 0;
 

src/usr.sbin/ntpd/util.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.11 2006/06/07 06:29:03 otto Exp $ */
+/*	$OpenBSD: util.c,v 1.12 2006/10/27 12:22:41 henning Exp $ */
 
 /*
  * Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org>
@@ -47,6 +47,17 @@ gettime(void)
 	return (tv.tv_sec + JAN_1970 + 1.0e-6 * tv.tv_usec);
 }
 
+time_t
+getmonotime(void)
+{
+	struct timespec	ts;
+
+	if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+		fatal("clock_gettime");
+
+	return (ts.tv_sec);
+}
+
 
 void
 d_to_tv(double d, struct timeval *tv)