Be more aggressive retrying dns while in settime mode. The constraint

engine does not know if we're in startup mode, so use a small interval
the first few times there.

src/usr.sbin/ntpd/client.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.107 2019/06/09 08:40:54 otto Exp $ */
+/*	$OpenBSD: client.c,v 1.108 2019/06/16 07:36:25 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -129,8 +129,11 @@ client_query(struct ntp_peer *p)
 	int	val;
 
 	if (p->addr == NULL && client_nextaddr(p) == -1) {
-		set_next(p, MAXIMUM(SETTIME_TIMEOUT,
-		    scale_interval(INTERVAL_QUERY_AGGRESSIVE)));
+		if (conf->settime)
+			set_next(p, INTERVAL_AUIO_DNSFAIL);
+		else
+			set_next(p, MAXIMUM(SETTIME_TIMEOUT,
+			    scale_interval(INTERVAL_QUERY_AGGRESSIVE)));
 		return (0);
 	}
 

src/usr.sbin/ntpd/constraint.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: constraint.c,v 1.45 2019/06/09 08:40:54 otto Exp $	*/
+/*	$OpenBSD: constraint.c,v 1.46 2019/06/16 07:36:25 otto Exp $	*/
 
 /*
  * Copyright (c) 2015 Reyk Floeter <reyk@openbsd.org>
@@ -157,7 +157,9 @@ constraint_query(struct constraint *cstr)
 		/* Proceed and query the time */
 		break;
 	case STATE_DNS_TEMPFAIL:
-		if (now > cstr->last + CONSTRAINT_RETRY_INTERVAL) {
+		if (now > cstr->last + (cstr->dnstries >= TRIES_AUTO_DNSFAIL ?
+		    CONSTRAINT_RETRY_INTERVAL : INTERVAL_AUIO_DNSFAIL)) {
+			cstr->dnstries++;
 			/* Retry resolving the address */
 			constraint_init(cstr);
 			return 0;

src/usr.sbin/ntpd/ntp.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.154 2019/06/12 05:04:45 otto Exp $ */
+/*	$OpenBSD: ntp.c,v 1.155 2019/06/16 07:36:25 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -520,6 +520,8 @@ ntp_dispatch_imsg_dns(void)
 			if (dlen == 0) {	/* no data -> temp error */
 				log_warnx("DNS lookup tempfail");
 				peer->state = STATE_DNS_TEMPFAIL;
+				if (++conf->tmpfail > TRIES_AUTO_DNSFAIL)
+					priv_settime(0);
 				break;
 			}
 

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.142 2019/06/12 05:04:45 otto Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.143 2019/06/16 07:36:25 otto Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -69,6 +69,8 @@
 #define FILTER_ADJFREQ		0x01	/* set after doing adjfreq */
 #define AUTO_REPLIES    	4	/* # of ntp replies we want for auto */
 #define AUTO_THRESHOLD		60	/* dont bother auto setting < this */
+#define INTERVAL_AUIO_DNSFAIL	1	/* DNS tmpfail interval for auto */
+#define TRIES_AUTO_DNSFAIL	4	/* DNS tmpfail quick retries */
 
 
 #define	SENSOR_DATA_MAXAGE		(15*60)
@@ -199,6 +201,7 @@ struct constraint {
 	struct imsgbuf			 ibuf;
 	time_t				 last;
 	time_t				 constraint;
+	int				 dnstries;
 };
 
 struct ntp_conf_sensor {
@@ -241,6 +244,7 @@ struct ntpd_conf {
 	u_int						constraint_errors;
 	u_int8_t					*ca;
 	size_t						ca_len;
+	int						tmpfail;
 };
 
 struct ctl_show_status {