Compensate old offsets with the amount of adjustment done, avoiding

overcompensating. From DragonFly, uses recent adjtime(2) changes,
so you'll need a recent kernel. ok henning@

src/usr.sbin/ntpd/client.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.69 2006/06/04 18:58:13 otto Exp $ */
+/*	$OpenBSD: client.c,v 1.70 2006/06/07 06:29:03 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -161,7 +161,7 @@ client_query(struct ntp_peer *p)
 
 	p->query->msg.xmttime.int_partl = arc4random();
 	p->query->msg.xmttime.fractionl = arc4random();
-	p->query->xmttime = gettime();
+	p->query->xmttime = gettime_corrected();
 
 	if (ntp_sendmsg(p->query->fd, NULL, &p->query->msg,
 	    NTP_MSGSIZE_NOAUTH, 0) == -1) {
@@ -196,7 +196,7 @@ client_dispatch(struct ntp_peer *p, u_int8_t settime)
 			fatal("recvfrom");
 	}
 
-	T4 = gettime();
+	T4 = gettime_corrected();
 
 	ntp_getmsg((struct sockaddr *)&p->addr->ss, buf, size, &msg);
 

src/usr.sbin/ntpd/ntp.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.83 2006/06/04 18:58:13 otto Exp $ */
+/*	$OpenBSD: ntp.c,v 1.84 2006/06/07 06:29:03 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -500,8 +500,11 @@ priv_adjtime(void)
 
 	free(offsets);
 
-	TAILQ_FOREACH(p, &conf->ntp_peers, entry)
+	TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
+		for (i = 0; i < OFFSET_ARRAY_SIZE; i++)
+			p->reply[i].offset -= offset_median;
 		p->update.good = 0;
+	}
 
 	return (0);
 }
@@ -551,6 +554,7 @@ priv_host_dns(char *name, u_int32_t peerid)
 void
 update_scale(double offset)
 {
+	offset += getoffset();
 	if (offset < 0)
 		offset = -offset;
 

src/usr.sbin/ntpd/ntpd.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.c,v 1.41 2006/02/21 23:47:00 stevesk Exp $ */
+/*	$OpenBSD: ntpd.c,v 1.42 2006/06/07 06:29:03 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -320,6 +320,7 @@ ntpd_adjtime(double d)
 	int		synced = 0;
 	static int	firstadj = 1;
 
+	d += getoffset();
 	if (d >= (double)LOG_NEGLIGEE / 1000 ||
 	    d <= -1 * (double)LOG_NEGLIGEE / 1000)
 		log_info("adjusting local clock by %fs", d);

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.70 2006/06/04 18:58:13 otto Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.71 2006/06/07 06:29:03 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -276,6 +276,8 @@ time_t	error_interval(void);
 void	set_next(struct ntp_peer *, time_t);
 
 /* util.c */
+double			gettime_corrected(void);
+double			getoffset(void);
 double			gettime(void);
 void			d_to_tv(double, struct timeval *);
 double			lfp_to_d(struct l_fixedpt);

src/usr.sbin/ntpd/server.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: server.c,v 1.28 2006/01/19 11:20:23 dtucker Exp $ */
+/*	$OpenBSD: server.c,v 1.29 2006/06/07 06:29:03 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -137,7 +137,7 @@ server_dispatch(int fd, struct ntpd_conf *conf)
 			fatal("recvfrom");
 	}
 
-	rectime = gettime();
+	rectime = gettime_corrected();
 
 	if (ntp_getmsg((struct sockaddr *)&fsa, buf, size, &query) == -1)
 		return (0);
@@ -160,7 +160,7 @@ server_dispatch(int fd, struct ntpd_conf *conf)
 	reply.precision = conf->status.precision;
 	reply.rectime = d_to_lfp(rectime);
 	reply.reftime = d_to_lfp(conf->status.reftime);
-	reply.xmttime = d_to_lfp(gettime());
+	reply.xmttime = d_to_lfp(gettime_corrected());
 	reply.orgtime = query.xmttime;
 	reply.rootdelay = d_to_sfp(conf->status.rootdelay);
 

src/usr.sbin/ntpd/util.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.10 2004/12/08 15:47:38 mickey Exp $ */
+/*	$OpenBSD: util.c,v 1.11 2006/06/07 06:29:03 otto Exp $ */
 
 /*
  * Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org>
@@ -21,6 +21,21 @@
 
 #include "ntpd.h"
 
+double
+gettime_corrected(void)
+{
+	return (gettime() + getoffset());
+}
+
+double
+getoffset(void)
+{
+	struct timeval	tv;
+	if (adjtime(NULL, &tv) == -1)
+		return (0.0);
+	return (tv.tv_sec + 1.0e-6 * tv.tv_usec);
+}
+
 double
 gettime(void)
 {