Don't BIND DHCP socket if more interfaces may come along later.

Also make man page on this clearer, as it's been confusing many.

CHANGELOG

@@ -47,6 +47,15 @@ version 2.67
 	    Remove restriction on prefix-length in --auth-zone. Thanks
 	    to Toke Hoiland-Jorgensen for suggesting this.
 
+	    Log when the maximum number of concurrent DNS queries is
+	    reached. Thanks to Marcelo Salhab Brogliato for the patch.
+
+	    If wildcards are used in --interface, don't assume that 
+	    there will only ever be one available interface for DHCP
+	    just because there is one at start-up. More may appear, so
+	    we can't use SO_BINDTODEVICE. Thanks to Natrio for the bug
+	    report. 
+
 		
 version 2.66
             Add the ability to act as an authoritative DNS

man/dnsmasq.8

@@ -574,9 +574,11 @@ 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, except that A and AAAA records must be in one of the
+will be served. A and AAAA records must be in one of the
 specified subnets, or in a subnet corresponding to a constructed DHCP
-range. The subnet(s) are also used to define in-addr.arpa and
+range. (This can be overridden with 
+.B constructor-noauth:
+) The subnet(s) are also used to define in-addr.arpa and
 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
@@ -649,7 +651,22 @@ This forms a template which describes how to create ranges, based on the address
 
 .B --dhcp-range=::1,::400,constructor:eth0
 
-will look for addresses of the form <network>::1 on eth0 and then create a range from <network>::1 to <network>::400. If the interface is assigned more than one network, then the corresponding ranges will be automatically created, and then deprecated and finally removed again as the address is deprecated and then deleted. The interface name may have a final "*" wildcard.
+will look for addresses of the form <network>::1 or <network>:400 on
+eth0 and then create a range from <network>::1 to <network>::400. If
+the interface is assigned more than one network, then the
+corresponding ranges will be automatically created, and then
+deprecated and finally removed again as the address is deprecated and
+then deleted. The interface name may have a final "*" wildcard. Note
+that just any address on eth0 will not do: the non-prefix part must be
+equal either the start or end address given in the dhcp-range. This is
+to prevent prefixes becoming perpetual if the interface 
+gains a SLAAC address for the prefix when it is advertised by dnsmasq.
+
+There is a variant of the constructor: syntax using the keyword
+.B constructor-noauth.
+See 
+.B --auth-zone
+for an explanation of this.
 
 The optional 
 .B set:<tag> 

src/auth.c

@@ -54,6 +54,7 @@ static int filter_constructed_dhcp(struct auth_zone *zone, int flag, struct all_
   if (flag & F_IPV6)
     for (context = daemon->dhcp6; context; context = context->next)
       if ((context->flags & CONTEXT_CONSTRUCTED) &&
+	  !(context->flags & CONTEXT_NOAUTH) &&
 	  is_same_net6(&(addr_u->addr.addr6), &context->start6, context->prefix))
 	return 1;
 #endif

src/dhcp-common.c

@@ -347,21 +347,27 @@ void bindtodevice(int fd)
      to that device. This is for the use case of  (eg) OpenStack, which runs a new
      dnsmasq instance for each VLAN interface it creates. Without the BINDTODEVICE, 
      individual processes don't always see the packets they should.
-     SO_BINDTODEVICE is only available Linux. */
+     SO_BINDTODEVICE is only available Linux. 
+
+     Note that if wildcards are used in --interface, or a configured interface doesn't
+     yet exist, then more interfaces may arrive later, so we can't safely assert there
+     is only one interface and proceed.
+*/
   
   struct irec *iface, *found;
-  
+  struct iname *if_tmp;
+
+  for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next)
+    if (if_tmp->name && (!if_tmp->used || strchr(if_tmp->name, '*')))
+      return;
+
   for (found = NULL, iface = daemon->interfaces; iface; iface = iface->next)
     if (iface->dhcp_ok)
       {
 	if (!found)
 	  found = iface;
 	else if (strcmp(found->name, iface->name) != 0) 
-	  {
-	    /* more than one. */
-	    found = NULL;
-	    break;
-	  }
+	  return; /* more than one. */
       }
   
   if (found)

src/dhcp6.c

@@ -538,7 +538,9 @@ static int construct_worker(struct in6_addr *local, int prefix,
 	  }
 	
       }
-    else if (addr6part(local) == addr6part(&template->start6) && wildcard_match(template->template_interface, ifrn_name))
+    else if ((addr6part(local) == addr6part(&template->start6) ||
+	      addr6part(local) == addr6part(&template->end6)) && 
+	     wildcard_match(template->template_interface, ifrn_name))
       {
 	start6 = *local;
 	setaddr6part(&start6, addr6part(&template->start6));

src/dnsmasq.h

@@ -731,6 +731,7 @@ struct dhcp_context {
 #define CONTEXT_RA          8192
 #define CONTEXT_CONF_USED  16384
 #define CONTEXT_USED       32768
+#define CONTEXT_NOAUTH     65536
 
 struct ping_result {
   struct in_addr addr;

src/forward.c

@@ -1205,8 +1205,17 @@ struct frec *get_new_frec(time_t now, int *wait)
   /* none available, calculate time 'till oldest record expires */
   if (count > daemon->ftabsize)
     {
+      static time_t last_log = 0;
+      
       if (oldest && wait)
 	*wait = oldest->time + (time_t)TIMEOUT - now;
+      
+      if ((int)difftime(now, last_log) > 5)
+	{
+	  last_log = now;
+	  my_syslog(LOG_WARNING, _("Maximum number of concurrent DNS queries reached (max: %d)"), daemon->ftabsize);
+	}
+
       return NULL;
     }
   

src/option.c

@@ -2409,6 +2409,11 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		    new->template_interface = opt_string_alloc(a[leasepos] + 12);
 		    new->flags |= CONTEXT_TEMPLATE;
 		  }
+		else if (strstr(a[leasepos], "constructor-noauth:") == a[leasepos])
+		  {
+		    new->template_interface = opt_string_alloc(a[leasepos] + 19);
+		    new->flags |= CONTEXT_TEMPLATE | CONTEXT_NOAUTH;
+		  }
 		else  
 		  break;
 	      }