Extend /4 and /6 syntax to --interface-name

man/dnsmasq.8

@@ -199,7 +199,12 @@ or
 .B --listen-address
 configuration, indeed
 .B --auth-server
-will overide these and provide a different DNS service on the specified interface. The <domain> is the "glue record". It should resolve in the global DNS to a A and/or AAAA record which points to the address dnsmasq is listening on.
+will overide these and provide a different DNS service on the
+specified interface. The <domain> is the "glue record". It should
+resolve in the global DNS to a A and/or AAAA record which points to
+the address dnsmasq is listening on. When an interface is specified,
+it may be qualified with "/4" or "/6" to specify only the IPv4 or IPv6
+addresses associated with the interface.
 .TP 
 .B \-2, --no-dhcp-interface=<interface name>
 Do not provide DHCP or TFTP on the specified interface, but do provide DNS service.
@@ -509,11 +514,13 @@ record (which is always in the C_IN class). The value of the record is
 given by the hex data, which may be of the form 01:23:45 or 01 23 45 or
 012345 or any mixture of these.
 .TP
-.B --interface-name=<name>,<interface>
+.B --interface-name=<name>,<interface>[/4|/6]
 Return a DNS record associating the name with the primary address on
-the given interface. This flag specifies an A record for the given
+the given interface. This flag specifies an A or AAAA record for the given
 name in the same way as an /etc/hosts line, except that the address is
-not constant, but taken from the given interface. If the interface is
+not constant, but taken from the given interface. The interface may be
+followed by "/4" or "/6" to specify that only IPv4 or IPv6 addresses
+of the interface should be used. If the interface is
 down, not configured or non-existent, an empty record is returned. The
 matching PTR record is also created, mapping the interface address to
 the name. More than one name may be associated with an interface
@@ -588,8 +595,10 @@ needed for a client to do validation itself.
 .TP
 .B --auth-zone=<domain>[,<subnet>[/<prefix length>][,<subnet>[/<prefix length>].....]]
 Define a DNS zone for which dnsmasq acts as authoritative server. Locally defined DNS records which are in the domain
-will be served. A and AAAA records must be in one of the
-specified subnets. As alternative to directly specifying the subnets, it's possible to
+will be served. If subnet(s) are given, A and AAAA records must be in one of the
+specified subnets.
+
+As alternative to directly specifying the subnets, it's possible to
 give the name of an interface, in which case the subnets implied by
 that interface's configured addresses and netmask/prefix-length are
 used; this is useful when using constructed DHCP ranges as the actual
@@ -606,7 +615,8 @@ ipv6.arpa domains which are served for reverse-DNS queries. If not
 specified, the prefix length defaults to 24 for IPv4 and 64 for IPv6.
 For IPv4 subnets, the prefix length should be have the value 8, 16 or 24
 unless you are familiar with RFC 2317 and have arranged the
-in-addr.arpa delegation accordingly. 
+in-addr.arpa delegation accordingly. Note that if no subnets are
+specified, then no reverse queries are answered.
 .TP
 .B --auth-soa=<serial>[,<hostmaster>[,<refresh>[,<retry>[,<expiry>]]]]
 Specify fields in the SOA record associated with authoritative

src/auth.c

@@ -18,7 +18,7 @@
 
 #ifdef HAVE_AUTH
 
-static struct addrlist *filter_zone(struct auth_zone *zone, int flag, struct all_addr *addr_u)
+static struct addrlist *find_subnet(struct auth_zone *zone, int flag, struct all_addr *addr_u)
 {
   struct addrlist *subnet;
 
@@ -45,6 +45,15 @@ static struct addrlist *filter_zone(struct auth_zone *zone, int flag, struct all
   return NULL;
 }
 
+static int filter_zone(struct auth_zone *zone, int flag, struct all_addr *addr_u)
+{
+  /* No zones specified, no filter */
+  if (!zone->subnet)
+    return 1;
+  
+  return find_subnet(zone, flag, addr_u) != NULL;
+}
+
 int in_zone(struct auth_zone *zone, char *name, char **cut)
 {
   size_t namelen = strlen(name);
@@ -130,7 +139,7 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 	  if (!local_query)
 	    {
 	      for (zone = daemon->auth_zones; zone; zone = zone->next)
-		if ((subnet = filter_zone(zone, flag, &addr)))
+		if ((subnet = find_subnet(zone, flag, &addr)))
 		  break;
 	      
 	      if (!zone)
@@ -660,16 +669,16 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 		  *cut = 0;
 		
 		for (addrlist = intr->addr; addrlist; addrlist = addrlist->next) 
-		  if (!(subnet->flags & ADDRLIST_IPV6) &&
-		      (local_query || filter_zone(zone, F_IPV4,  &addrlist->addr)) && 
+		  if (!(addrlist->flags & ADDRLIST_IPV6) &&
+		      (local_query || filter_zone(zone, F_IPV4, &addrlist->addr)) && 
 		      add_resource_record(header, limit, &trunc, -axfroffset, &ansp, 
 					  daemon->auth_ttl, NULL, T_A, C_IN, "4", cut ? intr->name : NULL, &addrlist->addr))
 		    anscount++;
 		
 #ifdef HAVE_IPV6
 		for (addrlist = intr->addr; addrlist; addrlist = addrlist->next) 
-		  if ((subnet->flags & ADDRLIST_IPV6) && 
-		      (local_query || filter_zone(zone, F_IPV6,  &addrlist->addr)) &&
+		  if ((addrlist->flags & ADDRLIST_IPV6) && 
+		      (local_query || filter_zone(zone, F_IPV6, &addrlist->addr)) &&
 		      add_resource_record(header, limit, &trunc, -axfroffset, &ansp, 
 					  daemon->auth_ttl, NULL, T_AAAA, C_IN, "6", cut ? intr->name : NULL, &addrlist->addr))
 		    anscount++;

src/dnsmasq.c

@@ -636,7 +636,10 @@ int main (int argc, char **argv)
   if (bind_fallback)
     my_syslog(LOG_WARNING, _("setting --bind-interfaces option because of OS limitations"));
 
-  warn_bound_listeners();
+  if (option_bool(OPT_NOWILD))
+    warn_bound_listeners();
+
+  warn_int_names();
   
   if (!option_bool(OPT_NOWILD)) 
     for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next)

src/dnsmasq.h

@@ -321,6 +321,7 @@ struct host_record {
 struct interface_name {
   char *name; /* domain name */
   char *intr; /* interface name */
+  int family; /* AF_INET, AF_INET6 or zero for both */
   struct addrlist *addr;
   struct interface_name *next;
 };
@@ -1076,6 +1077,7 @@ int enumerate_interfaces(int reset);
 void create_wildcard_listeners(void);
 void create_bound_listeners(int die);
 void warn_bound_listeners(void);
+void warn_int_names(void);
 int is_dad_listeners(void);
 int iface_check(int family, struct all_addr *addr, char *name, int *auth_dns);
 int loopback_exception(int fd, int family, struct all_addr *addr, char *name);

src/network.c

@@ -159,7 +159,8 @@ int iface_check(int family, struct all_addr *addr, char *name, int *auth)
   for (tmp = daemon->authinterface; tmp; tmp = tmp->next)
     if (tmp->name)
       {
-	if (strcmp(tmp->name, name) == 0)
+	if (strcmp(tmp->name, name) == 0 &&
+	    (tmp->addr.sa.sa_family == 0 || tmp->addr.sa.sa_family == family))
 	  break;
       }
     else if (addr && tmp->addr.sa.sa_family == AF_INET && family == AF_INET &&
@@ -329,7 +330,8 @@ static int iface_allowed(struct iface_param *param, int if_index, char *label,
       /* Update addresses from interface_names. These are a set independent
 	 of the set we're listening on. */  
       for (int_name = daemon->int_names; int_name; int_name = int_name->next)
-	if (strncmp(label, int_name->intr, IF_NAMESIZE) == 0)
+	if (strncmp(label, int_name->intr, IF_NAMESIZE) == 0 && 
+	    (addr->sa.sa_family == int_name->family || int_name->family == 0))
 	  {
 	    if (param->spare)
 	      {
@@ -914,7 +916,7 @@ void warn_bound_listeners(void)
   int advice = 0;
 
   for (iface = daemon->interfaces; iface; iface = iface->next)
-    if (option_bool(OPT_NOWILD) && !iface->dns_auth)
+    if (!iface->dns_auth)
       {
 	int warn = 0;
 	if (iface->addr.sa.sa_family == AF_INET)
@@ -942,15 +944,24 @@ void warn_bound_listeners(void)
 	  {
 	    iface->warned = advice = 1;
 	    my_syslog(LOG_WARNING, 
-		      _("LOUD WARNING: listening on %s may accept requests via interfaces other than %s. "),
+		      _("LOUD WARNING: listening on %s may accept requests via interfaces other than %s"),
 		      daemon->addrbuff, iface->name);
 	  }
       }
   
   if (advice)
-    my_syslog(LOG_WARNING, _("LOUD WARNING: use --bind-dynamic rather than --bind-interfaces to avoid DNS amplification attacks via these interface(s).")); 
+    my_syslog(LOG_WARNING, _("LOUD WARNING: use --bind-dynamic rather than --bind-interfaces to avoid DNS amplification attacks via these interface(s)")); 
 }
 
+void warn_int_names(void)
+{
+  struct interface_name *intname;
+ 
+  for (intname = daemon->int_names; intname; intname = intname->next)
+    if (!intname->addr)
+      my_syslog(LOG_WARNING, _("warning: no addresses found for interface %s"), intname->intr);
+}
+ 
 int is_dad_listeners(void)
 {
   struct irec *iface;

src/option.c

@@ -1615,8 +1615,22 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	  new->addr.sa.sa_family = AF_INET6;
 #endif
 	else
-	  new->name = opt_string_alloc(arg);
-	
+	  {
+	    char *fam = split_chr(arg, '/');
+	    new->name = opt_string_alloc(arg);
+	    new->addr.sa.sa_family = 0;
+	    if (fam)
+	      {
+		if (strcmp(fam, "4") == 0)
+		  new->addr.sa.sa_family = AF_INET;
+#ifdef HAVE_IPV6
+		else if (strcmp(fam, "6") == 0)
+		  new->addr.sa.sa_family = AF_INET6;
+#endif
+		else
+		  ret_err(gen_err);
+	      } 
+	  }
 	new->next = daemon->authinterface;
 	daemon->authinterface = new;
 	
@@ -3362,6 +3376,19 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	for (up = &daemon->int_names; *up; up = &((*up)->next));
 	*up = new;
 	new->name = domain;
+	new->family = 0;
+	arg = split_chr(comma, '/');
+	if (arg)
+	  {
+	    if (strcmp(arg, "4") == 0)
+	      new->family = AF_INET;
+#ifdef HAVE_IPV6
+	    else if (strcmp(arg, "6") == 0)
+	      new->family = AF_INET6;
+#endif
+	    else
+	      ret_err(gen_err);
+	  } 
 	new->intr = opt_string_alloc(comma);
 	break;
       }

src/radv.c

@@ -205,7 +205,7 @@ static void send_ra(time_t now, int iface, char *iface_name, struct in6_addr *de
   struct dhcp_netid iface_id;
   struct dhcp_opt *opt_cfg;
   struct ra_interface *ra_param = find_iface_param(iface_name);
-  int done_dns = 0;
+  int done_dns = 0, old_prefix = 0;
 #ifdef HAVE_LINUX_NETWORK
   FILE *f;
 #endif
@@ -267,7 +267,7 @@ static void send_ra(time_t now, int iface, char *iface_name, struct in6_addr *de
 	      struct in6_addr local = context->start6;
 	      int do_slaac = 0;
 
-	      parm.found_context = 1;
+	      old_prefix = 1;
 
 	      /* zero net part of address */
 	      setaddr6part(&local, addr6part(&local) & ~((context->prefix == 64) ? (u64)-1LL : (1LLU << (128 - context->prefix)) - 1LLU));
@@ -300,9 +300,14 @@ static void send_ra(time_t now, int iface, char *iface_name, struct in6_addr *de
 	up = &context->next;
     }
     
-  if (!parm.found_context)
-    return;
-    
+  /* If we're advertising only old prefixes, set router lifetime to zero. */
+  if (old_prefix && !parm.found_context)
+    ra->lifetime = htons(0);
+
+  /* No prefixes to advertise. */
+  if (!old_prefix && !parm.found_context)
+    return; 
+  
 #ifdef HAVE_LINUX_NETWORK
   /* Note that IPv6 MTU is not necessarilly the same as the IPv4 MTU
      available from SIOCGIFMTU */