when a dns lookup fails at parse time, do not abort but try again

to resolve the hostname every 60 seconds
fixes ntpd invocations before e. g. a dialup link is established and such.
as we want ntpd to be a "fire and forget" background daemon it should
cope with such situations.
tested by many

src/usr.sbin/ntpd/client.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.28 2004/07/20 16:47:55 henning Exp $ */
+/*	$OpenBSD: client.c,v 1.29 2004/07/28 16:38:43 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -56,7 +56,8 @@ client_peer_init(struct ntp_peer *p)
 		}
 	}
 
-	if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 0)) == -1)
+	if (p->addr != NULL &&
+	    (p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 0)) == -1)
 		fatal("client_query socket");
 
 	p->query->msg.status = MODE_CLIENT | (NTP_VERSION << 3);
@@ -73,6 +74,15 @@ client_nextaddr(struct ntp_peer *p)
 {
 	close(p->query->fd);
 
+	if (p->addr_head.a == NULL) {
+		if (host_dns(p->addr_head.name, &p->addr_head.a) > 0) {
+			p->addr = p->addr_head.a;
+			p->shift = 0;
+			p->trustlevel = TRUSTLEVEL_PATHETIC;
+		} else
+			return (-1);
+	}
+
 	if ((p->addr = p->addr->next) == NULL)
 		p->addr = p->addr_head.a;
 
@@ -88,6 +98,11 @@ client_nextaddr(struct ntp_peer *p)
 int
 client_query(struct ntp_peer *p)
 {
+	if (p->addr == NULL && client_nextaddr(p) == -1) {
+		p->next = time(NULL) + INTERVAL_QUERY_PATHETIC;
+		return (-1);
+	}
+
 	/*
 	 * Send out a random 64-bit number as our transmit time.  The NTP
 	 * server will copy said number into the originate field on the

src/usr.sbin/ntpd/config.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: config.c,v 1.8 2004/07/25 18:27:58 henning Exp $ */
+/*	$OpenBSD: config.c,v 1.9 2004/07/28 16:38:43 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -29,12 +29,12 @@
 
 struct ntp_addr	*host_v4(const char *);
 struct ntp_addr	*host_v6(const char *);
-struct ntp_addr	*host_dns(const char *);
 
-struct ntp_addr	*
-host(const char *s)
+int
+host(const char *s, struct ntp_addr **hn)
 {
-	struct ntp_addr		*h = NULL;
+	struct ntp_addr	*h = NULL;
+	int		 cnt = 1;
 
 	if (!strcmp(s, "*"))
 		if ((h = calloc(1, sizeof(struct ntp_addr))) == NULL)
@@ -50,9 +50,10 @@ host(const char *s)
 
 	/* Hostname? */
 	if (h == NULL)
-		h = host_dns(s);
+		cnt = host_dns(s, &h);
 
-	return (h);
+	*hn = h;
+	return (cnt);
 }
 
 struct ntp_addr	*
@@ -105,11 +106,11 @@ host_v6(const char *s)
 	return (h);
 }
 
-struct ntp_addr	*
-host_dns(const char *s)
+int
+host_dns(const char *s, struct ntp_addr **hn)
 {
 	struct addrinfo		 hints, *res0, *res;
-	int			 error;
+	int			 error, cnt = 0;
 	struct sockaddr_in	*sa_in;
 	struct sockaddr_in6	*sa_in6;
 	struct ntp_addr		*h, *hh = NULL;
@@ -118,8 +119,14 @@ host_dns(const char *s)
 	hints.ai_family = PF_UNSPEC;
 	hints.ai_socktype = SOCK_STREAM; /* DUMMY */
 	error = getaddrinfo(s, NULL, &hints, &res0);
-	if (error)
-		return (NULL);
+	if (error) {
+		log_warnx("could not parse \"%s\": %s", s,
+		    gai_strerror(error));
+		if (error == EAI_AGAIN || error == EAI_NODATA)
+			return (0);
+		else
+			return (-1);
+	}
 
 	for (res = res0; res; res = res->ai_next) {
 		if (res->ai_family != AF_INET &&
@@ -142,8 +149,10 @@ host_dns(const char *s)
 
 		h->next = hh;
 		hh = h;
+		cnt++;
 	}
 	freeaddrinfo(res0);
 
-	return (hh);
+	*hn = hh;
+	return (cnt);
 }

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.29 2004/07/25 18:27:58 henning Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.30 2004/07/28 16:38:43 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -206,7 +206,8 @@ int	 parse_config(char *, struct ntpd_conf *);
 int	 cmdline_symset(char *);
 
 /* config.c */
-struct ntp_addr	*host(const char *);
+int	 host(const char *, struct ntp_addr **);
+int	 host_dns(const char *, struct ntp_addr **);
 
 /* ntp_msg.c */
 int	ntp_getmsg(char *, ssize_t, struct ntp_msg *);

src/usr.sbin/ntpd/parse.y

@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.y,v 1.14 2004/07/21 09:40:55 henning Exp $ */
+/*	$OpenBSD: parse.y,v 1.15 2004/07/28 16:38:43 henning Exp $ */
 
 /*
  * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -211,7 +211,7 @@ address		: STRING		{
 			if (($$ = calloc(1, sizeof(struct ntp_addr_wrap))) ==
 			    NULL)
 				fatal(NULL);
-			if (($$->a = host($1)) == NULL) {
+			if (host($1, &$$->a) == -1) {
 				yyerror("could not parse address spec \"%s\"",
 				    $1);
 				free($1);