Compare address and interface index for allowed interface

If interface is recreated with the same address but different index, it
would not change any other parameter.

Test also address family on incoming TCP queries.

src/dnsmasq.c

@@ -1824,7 +1824,8 @@ static void check_dns_listeners(time_t now)
 		    addr.addr4 = tcp_addr.in.sin_addr;
 		  
 		  for (iface = daemon->interfaces; iface; iface = iface->next)
-		    if (iface->index == if_index)
+		    if (iface->index == if_index &&
+		        iface->addr.sa.sa_family == tcp_addr.sa.sa_family)
 		      break;
 		  
 		  if (!iface && !loopback_exception(listener->tcpfd, tcp_addr.sa.sa_family, &addr, intr_name))

src/network.c

@@ -388,10 +388,11 @@ static int iface_allowed(struct iface_param *param, int if_index, char *label,
   /* check whether the interface IP has been added already 
      we call this routine multiple times. */
   for (iface = daemon->interfaces; iface; iface = iface->next) 
-    if (sockaddr_isequal(&iface->addr, addr))
+    if (sockaddr_isequal(&iface->addr, addr) && iface->index == if_index)
       {
 	iface->dad = !!(iface_flags & IFACE_TENTATIVE);
 	iface->found = 1; /* for garbage collection */
+	iface->netmask = netmask;
 	return 1;
       }