rework dns handling with all its cosequences...

we know have both a "server" and "servers" keyword. they differ when the
hostname resolves to more than one IP, server picks one and servers expands
to all.
that means no longer stuffing a sockaddr_storage into ntp_peer but a pointer
to a linked list of ntp_addr structs.
in the "servers" case the list of n addresses returned by host() is expanded
into n ntp_peer structs and thus n individual peers.
in the "server" case the whole list is attached to ntp_peer, and whenever we
do not receive a reply in time we traverse the list one further, so that
hosts with both AAAA and A records are first tried with the AAAA one but
we gracefully fall back to the A one.
semantics with theo; hacked up on the Montreal->Frankfurt flight.
again Air Canada surprised me, that older 767 hat pretty decent seats.

src/usr.sbin/ntpd/client.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.17 2004/07/08 01:20:21 henning Exp $ */
+/*	$OpenBSD: client.c,v 1.18 2004/07/09 10:53:33 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -31,27 +31,30 @@ client_peer_init(struct ntp_peer *p)
 {
 	struct sockaddr_in	*sa_in;
 	struct sockaddr_in6	*sa_in6;
+	struct ntp_addr		*h;
 
 	if ((p->query = calloc(1, sizeof(struct ntp_query))) == NULL)
 		fatal("client_query calloc");
 
-	switch (p->ss.ss_family) {
-	case AF_INET:
-		sa_in = (struct sockaddr_in *)&p->ss;
-		if (ntohs(sa_in->sin_port) == 0)
-			sa_in->sin_port = htons(123);
-		break;
-	case AF_INET6:
-		sa_in6 = (struct sockaddr_in6 *)&p->ss;
-		if (ntohs(sa_in6->sin6_port) == 0)
-			sa_in6->sin6_port = htons(123);
-		break;
-	default:
-		fatal("king bula sez: wrong AF in client_peer_init");
-		/* not reached */
+	for (h = p->addr; h != NULL; h = h->next) {
+		switch (h->ss.ss_family) {
+		case AF_INET:
+			sa_in = (struct sockaddr_in *)&h->ss;
+			if (ntohs(sa_in->sin_port) == 0)
+				sa_in->sin_port = htons(123);
+			break;
+		case AF_INET6:
+			sa_in6 = (struct sockaddr_in6 *)&h->ss;
+			if (ntohs(sa_in6->sin6_port) == 0)
+				sa_in6->sin6_port = htons(123);
+			break;
+		default:
+			fatal("king bula sez: wrong AF in client_peer_init");
+			/* not reached */
+		}
 	}
 
-	if ((p->query->fd = socket(p->ss.ss_family, SOCK_DGRAM, 0)) == -1)
+	if ((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);
@@ -63,6 +66,23 @@ client_peer_init(struct ntp_peer *p)
 	return (0);
 }
 
+int
+client_nextaddr(struct ntp_peer *p)
+{
+	close(p->query->fd);
+
+	if ((p->addr = p->addr->next) == NULL)
+		p->addr = p->addr_head;
+
+	if ((p->query->fd = socket(p->addr->ss.ss_family, SOCK_DGRAM, 0)) == -1)
+		fatal("client_query socket");
+
+	p->shift = 0;
+	p->trustlevel = TRUSTLEVEL_PATHETIC;
+
+	return (0);
+}
+
 int
 client_query(struct ntp_peer *p)
 {
@@ -84,8 +104,8 @@ client_query(struct ntp_peer *p)
 	p->query->msg.xmttime.fraction = arc4random();
 	p->query->xmttime = gettime();
 
-	ntp_sendmsg(p->query->fd, (struct sockaddr *)&p->ss, &p->query->msg,
-	    NTP_MSGSIZE_NOAUTH, 0);
+	ntp_sendmsg(p->query->fd, (struct sockaddr *)&p->addr->ss,
+	    &p->query->msg, NTP_MSGSIZE_NOAUTH, 0);
 	p->state = STATE_QUERY_SENT;
 	p->next = 0;
 	p->deadline = time(NULL) + QUERYTIME_MAX;

src/usr.sbin/ntpd/ntp.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.18 2004/07/09 10:22:07 henning Exp $ */
+/*	$OpenBSD: ntp.c,v 1.19 2004/07/09 10:53:33 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -164,7 +164,6 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 		TAILQ_FOREACH(p, &conf->ntp_peers, entry) {
 			if (p->next > 0 && p->next < nextaction)
 				nextaction = p->next;
-
 			if (p->next > 0 && p->next <= time(NULL))
 				client_query(p);
 
@@ -172,12 +171,14 @@ ntp_main(int pipe_prnt[2], struct ntpd_conf *conf)
 				nextaction = p->deadline;
 			if (p->deadline > 0 && p->deadline <= time(NULL)) {
 				log_debug("no reply from %s received in time",
-				    log_sockaddr((struct sockaddr *)&p->ss));
+				    log_sockaddr(
+				    (struct sockaddr *)&p->addr->ss));
 				if (p->trustlevel >= TRUSTLEVEL_BADPEER &&
 				    --p->trustlevel < TRUSTLEVEL_BADPEER)
 					log_info("peer %s now invalid",
 					    log_sockaddr(
-					    (struct sockaddr *)&p->ss));
+					    (struct sockaddr *)&p->addr->ss));
+				client_nextaddr(p);
 				client_query(p);
 			}
 
@@ -324,7 +325,7 @@ get_peer_update(struct ntp_peer *p, double *offset)
 	if (good < 8 && p->trustlevel > 0) {
 		if (p->trustlevel >= TRUSTLEVEL_BADPEER)
 			log_info("peer %s now invalid",
-			    log_sockaddr((struct sockaddr *)&p->ss));
+			    log_sockaddr((struct sockaddr *)&p->addr->ss));
 		p->trustlevel /= 2;
 	}
 

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.18 2004/07/08 01:22:57 henning Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.19 2004/07/09 10:53:33 henning Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -76,7 +76,8 @@ struct ntp_offset {
 
 struct ntp_peer {
 	TAILQ_ENTRY(ntp_peer)		 entry;
-	struct sockaddr_storage		 ss;
+	struct ntp_addr			*addr_head;
+	struct ntp_addr			*addr;
 	struct ntp_query		*query;
 	enum client_state		 state;
 	time_t				 next;
@@ -197,6 +198,7 @@ int	server_dispatch(int fd);
 
 /* client.c */
 int	client_peer_init(struct ntp_peer *);
+int	client_nextaddr(struct ntp_peer *);
 int	client_query(struct ntp_peer *);
 int	client_dispatch(struct ntp_peer *);
 

src/usr.sbin/ntpd/parse.y

@@ -1,4 +1,4 @@
-/*	$OpenBSD: parse.y,v 1.9 2004/07/08 15:06:43 henning Exp $ */
+/*	$OpenBSD: parse.y,v 1.10 2004/07/09 10:53:33 henning Exp $ */
 
 /*
  * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -77,7 +77,7 @@ typedef struct {
 %}
 
 %token	LISTEN ON
-%token	SERVER
+%token	SERVER SERVERS
 %token	ERROR
 %token	<v.string>		STRING
 %type	<v.number>		number
@@ -146,7 +146,7 @@ conf_main	: LISTEN ON address	{
 				free(h);
 			}
 		}
-		| SERVER address	{
+		| SERVERS address	{
 			struct ntp_peer		*p;
 			struct ntp_addr		*h, *next;
 
@@ -161,12 +161,32 @@ conf_main	: LISTEN ON address	{
 				p = calloc(1, sizeof(struct ntp_peer));
 				if (p == NULL)
 					fatal("conf_main server calloc");
-				memcpy(&p->ss, &h->ss,
-				    sizeof(struct sockaddr_storage));
+				h->next = NULL;
+				p->addr = h;
 				TAILQ_INSERT_TAIL(&conf->ntp_peers, p, entry);
-				free(h);
 			}
 		}
+		| SERVER address	{
+			struct ntp_peer		*p;
+			struct ntp_addr		*h, *next;
+
+			if ((p = calloc(1, sizeof(struct ntp_peer))) == NULL)
+				fatal("conf_main server calloc");
+			for (h = $2; h != NULL; h = next) {
+				next = h->next;
+				if (h->ss.ss_family != AF_INET &&
+				    h->ss.ss_family != AF_INET6) {
+					yyerror("IPv4 or IPv6 address "
+					    "or hostname expected");
+					YYERROR;
+				}
+				h->next = p->addr;
+				p->addr = h;
+			}
+
+			p->addr_head = p->addr;
+			TAILQ_INSERT_TAIL(&conf->ntp_peers, p, entry);
+		}
 		;
 
 address		: STRING		{
@@ -216,7 +236,8 @@ lookup(char *s)
 	static const struct keywords keywords[] = {
 		{ "listen",		LISTEN},
 		{ "on",			ON},
-		{ "server",		SERVER}
+		{ "server",		SERVER},
+		{ "servers",		SERVERS}
 	};
 	const struct keywords	*p;
 
@@ -434,7 +455,6 @@ parse_config(char *filename, struct ntpd_conf *xconf)
 
 	if ((fin = fopen(filename, "r")) == NULL) {
 		log_warn("%s", filename);
-		free(conf);
 		return (-1);
 	}
 	infile = filename;