@@ -4438,6 +4438,27 @@ fork_register_dns_action (struct tuntap *tt)

     }

 }

+static uint32_t

+dhcp_masq_addr (const in_addr_t local, const in_addr_t netmask, const int offset)

+{

+  struct gc_arena gc = gc_new ();

+  in_addr_t dsa; /* DHCP server addr */

+

+  if (offset < 0)

+    dsa = (local | (~netmask)) + offset;

+  else

+    dsa = (local & netmask) + offset;

+

+  if (dsa == local)

+    msg (M_FATAL, "ERROR: There is a clash between the --ifconfig local address and the internal DHCP server address -- both are set to %s -- please use the --ip-win32 dynamic option to choose a different free address from the --ifconfig subnet for the internal DHCP server", print_in_addr_t (dsa, 0, &gc));

+

+  if ((local & netmask) != (dsa & netmask))

+    msg (M_FATAL, "ERROR: --tap-win32 dynamic [offset] : offset is outside of --ifconfig subnet");

+

+  gc_free (&gc);

+  return htonl(dsa);

+}

+

 void

 open_tun (const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)

 {

@@ -4696,33 +4717,18 @@ open_tun (const char *dev, const char *dev_type, const char *dev_node, struct tu

 	{

 	  if (tt->topology == TOP_SUBNET)

 	    {

-	      const in_addr_t netmask_inv = ~tt->remote_netmask;

-	      ep[2] = netmask_inv ? htonl ((tt->local | netmask_inv) - 1) : 0;

+	      if (tt->options.dhcp_masq_custom_offset)

+		ep[2] = dhcp_masq_addr (tt->local, tt->remote_netmask, tt->options.dhcp_masq_offset);

+	      else

+		ep[2] = dhcp_masq_addr (tt->local, tt->remote_netmask, -1);

 	    }

 	  else

 	    ep[2] = htonl (tt->remote_netmask);

-

-	  if (tt->options.dhcp_masq_custom_offset)

-	    msg (M_WARN, "WARNING: because you are using '--dev tun' mode, the '--ip-win32 dynamic [offset]' option is ignoring the offset parameter");

 	}

       else

 	{

-	  in_addr_t dsa; /* DHCP server addr */

-

 	  ASSERT (tt->type == DEV_TYPE_TAP);

-

-	  if (tt->options.dhcp_masq_offset < 0)

-	    dsa = (tt->local | (~tt->adapter_netmask)) + tt->options.dhcp_masq_offset;

-	  else

-	    dsa = (tt->local & tt->adapter_netmask) + tt->options.dhcp_masq_offset;

-

-	  if (dsa == tt->local)

-	    msg (M_FATAL, "ERROR: There is a clash between the --ifconfig local address and the internal DHCP server address -- both are set to %s -- please use the --ip-win32 dynamic option to choose a different free address from the --ifconfig subnet for the internal DHCP server", print_in_addr_t (dsa, 0, &gc));

-

-	  if ((tt->local & tt->adapter_netmask) != (dsa & tt->adapter_netmask))

-	    msg (M_FATAL, "ERROR: --tap-win32 dynamic [offset] : offset is outside of --ifconfig subnet");

-

-	  ep[2] = htonl (dsa);

+	  ep[2] = dhcp_masq_addr (tt->local, tt->adapter_netmask, tt->options.dhcp_masq_custom_offset ? tt->options.dhcp_masq_offset : 0);

 	}

       /* lease time in seconds */