Fix a address family desynchronisation between lwres_conf and

dig_serverlist.
In one of the first shredding commits lwres unintentionally lost the
ability to track if the user requested IPv4 only or IPv6 only
operations. Parsing of /etc/resolv.conf would add all nameservers,
ignoring their address family.
When dig(1) later populated server_list it would pay attention to
the address family.

If /etc/resolv.conf contains only IPv4 nameservers and it has 3 or
more and the user requests IPv6 only operations dig would fail with
"add_nameserver failed". This happens because lwres_conf already
contains 3 nameservers but server_list is empty so dig tries to add
::1 to lwres_conf.

It feels like this is very convoluted but it restores previous
behavoir the way it was implemented before. Thus sidestepping some
refactoring.

OK millert

3 files changed, 21 insertions, 7 deletions

diff --git a/usr.sbin/bind/bin/dig/dighost.c b/usr.sbin/bind/bin/dig/dighost.c
index 9bb012b83a1..79666179a3c 100644
--- a/usr.sbin/bind/bin/dig/dighost.c
+++ b/usr.sbin/bind/bin/dig/dighost.c
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: dighost.c,v 1.30 2020/01/20 18:40:55 florian Exp $ */
+/* $Id: dighost.c,v 1.31 2020/01/20 18:41:48 florian Exp $ */
 
 /*! \file
  *  \note
@@ -1423,6 +1423,7 @@ void
 setup_system(isc_boolean_t ipv4only, isc_boolean_t ipv6only) {
 	dig_searchlist_t *domain = NULL;
 	lwres_result_t lwresult;
+	int lwresflags = 0;
 
 	debug("setup_system()");
 
@@ -1444,7 +1445,12 @@ setup_system(isc_boolean_t ipv4only, isc_boolean_t ipv6only) {
 		}
 	}
 
-	lwres_conf_init(lwconf);
+	if (have_ipv4)
+		lwresflags |= LWRES_USEIPV4;
+	if (have_ipv6)
+		lwresflags |= LWRES_USEIPV6;
+	lwres_conf_init(lwconf, lwresflags);
+
 	lwresult = lwres_conf_parse(lwconf, RESOLV_CONF);
 	if (lwresult != LWRES_R_SUCCESS && lwresult != LWRES_R_NOTFOUND)
 		fatal("parse of %s failed", RESOLV_CONF);
diff --git a/usr.sbin/bind/lib/lwres/include/lwres/lwres.h b/usr.sbin/bind/lib/lwres/include/lwres/lwres.h
index 2f64da0807d..5d546dee9cb 100644
--- a/usr.sbin/bind/lib/lwres/include/lwres/lwres.h
+++ b/usr.sbin/bind/lib/lwres/include/lwres/lwres.h
@@ -14,7 +14,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: lwres.h,v 1.5 2020/01/06 17:41:29 florian Exp $ */
+/* $Id: lwres.h,v 1.6 2020/01/20 18:41:48 florian Exp $ */
 
 #ifndef LWRES_LWRES_H
 #define LWRES_LWRES_H 1
@@ -84,6 +84,8 @@
  */
 
 #define LWRES_ADDR_MAXLEN	16	/*%< changing this breaks ABI */
+#define LWRES_USEIPV4		0x0001
+#define LWRES_USEIPV6		0x0002
 
 /*% lwres_addr_t */
 typedef struct lwres_addr lwres_addr_t;
@@ -133,6 +135,7 @@ typedef struct {
 	uint8_t	resdebug;      /*%< non-zero if 'options debug' set */
 	uint8_t	ndots;	       /*%< set to n in 'options ndots:n' */
 	uint8_t	no_tld_query;  /*%< non-zero if 'options no_tld_query' */
+	int	flags;
 } lwres_conf_t;
 
 #define LWRES_ADDRTYPE_V4		0x00000001U	/*%< ipv4 */
@@ -169,7 +172,7 @@ lwres_conf_print(lwres_conf_t *confdata, FILE *fp);
  */
 
 void
-lwres_conf_init(lwres_conf_t *confdata);
+lwres_conf_init(lwres_conf_t *confdata, int lwresflags);
 /**<
  * sets all internal fields to a default state. Used to initialize a new
  * lwres_conf_t structure (not reset a used on).
diff --git a/usr.sbin/bind/lib/lwres/lwconfig.c b/usr.sbin/bind/lib/lwres/lwconfig.c
index da6827b1e50..02635b9212b 100644
--- a/usr.sbin/bind/lib/lwres/lwconfig.c
+++ b/usr.sbin/bind/lib/lwres/lwconfig.c
@@ -200,7 +200,7 @@ lwres_resetaddr(lwres_addr_t *addr) {
 
 /*% intializes data structure for subsequent config parsing. */
 void
-lwres_conf_init(lwres_conf_t *confdata) {
+lwres_conf_init(lwres_conf_t *confdata, int lwresflags) {
 	int i;
 
 	confdata->nsnext = 0;
@@ -211,6 +211,7 @@ lwres_conf_init(lwres_conf_t *confdata) {
 	confdata->resdebug = 0;
 	confdata->ndots = 1;
 	confdata->no_tld_query = 0;
+	confdata->flags = lwresflags;
 
 	for (i = 0; i < LWRES_CONFMAXNAMESERVERS; i++)
 		lwres_resetaddr(&confdata->nameservers[i]);
@@ -258,7 +259,7 @@ lwres_conf_clear(lwres_conf_t *confdata) {
 static lwres_result_t
 lwres_conf_parsenameserver(lwres_conf_t *confdata,  FILE *fp) {
 	char word[LWRES_CONFMAXLINELEN];
-	int res;
+	int res, use_ipv4, use_ipv6;
 	lwres_addr_t address;
 
 	if (confdata->nsnext == LWRES_CONFMAXNAMESERVERS)
@@ -274,7 +275,11 @@ lwres_conf_parsenameserver(lwres_conf_t *confdata,  FILE *fp) {
 		return (LWRES_R_FAILURE); /* Extra junk on line. */
 
 	res = lwres_create_addr(word, &address, 1);
-	if (res == LWRES_R_SUCCESS) {
+	use_ipv4 = confdata->flags & LWRES_USEIPV4;
+	use_ipv6 = confdata->flags & LWRES_USEIPV4;
+	if (res == LWRES_R_SUCCESS &&
+	    ((address.family == LWRES_ADDRTYPE_V4 && use_ipv4) ||
+	    (address.family == LWRES_ADDRTYPE_V6 && use_ipv6))) {
 		confdata->nameservers[confdata->nsnext++] = address;
 	}