Enable external connection for routers

This allows routers to connect to external IPv6 addresses.

source/6LoWPAN/ws/ws_bbr_api.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, Arm Limited and affiliates.
+ * Copyright (c) 2018-2021, Arm Limited and affiliates.
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -47,7 +47,7 @@
 #include "DHCPv6_client/dhcpv6_client_api.h"
 #include "libDHCPv6/libDHCPv6_vendordata.h"
 #include "libNET/src/net_dns_internal.h"
-
+#include "platform/os_whiteboard.h"
 
 #include "ws_bbr_api.h"
 
@@ -450,6 +450,7 @@ static void ws_bbr_dodag_get(uint8_t *local_prefix_ptr, uint8_t *global_prefix_p
     memcpy(global_prefix_ptr, global_address, 8);
     return;
 }
+
 static void wisun_bbr_na_send(int8_t interface_id, const uint8_t target[static 16])
 {
     protocol_interface_info_entry_t *cur = protocol_stack_interface_info_get_by_id(interface_id);
@@ -461,6 +462,8 @@ static void wisun_bbr_na_send(int8_t interface_id, const uint8_t target[static 1
         return;
     }
 
+    whiteboard_os_modify(target, ADD);
+
     buffer_t *buffer = icmpv6_build_na(cur, false, true, true, target, NULL, ADDR_UNSPECIFIED);
     protocol_push(buffer);
     return;
@@ -522,6 +525,11 @@ static void ws_bbr_dhcp_server_dns_info_update(protocol_interface_info_entry_t *
     DHCPv6_server_service_set_vendor_data(cur->id, global_id, ARM_ENTERPRISE_NUMBER, dhcp_vendor_data_ptr, dhcp_vendor_data_len);
 }
 
+static void wisun_dhcp_address_remove_cb(int8_t interfaceId, uint8_t *targetAddress, void *prefix_info)
+{
+    whiteboard_os_modify(targetAddress, REMOVE);
+}
+
 static void ws_bbr_dhcp_server_start(protocol_interface_info_entry_t *cur, uint8_t *global_id, uint32_t dhcp_address_lifetime)
 {
     uint8_t ll[16];
@@ -535,7 +543,7 @@ static void ws_bbr_dhcp_server_start(protocol_interface_info_entry_t *cur, uint8
         tr_error("DHCPv6 Server create fail");
         return;
     }
-    DHCPv6_server_service_callback_set(cur->id, global_id, NULL, wisun_dhcp_address_add_cb);
+    DHCPv6_server_service_callback_set(cur->id, global_id, wisun_dhcp_address_remove_cb, wisun_dhcp_address_add_cb);
     //Check for anonymous mode
     bool anonymous = (configuration & BBR_DHCP_ANONYMOUS) ? true : false;