added response to confirmable unicast. (ARMmbed#1722)

Author: deepakvenugopal

source/6LoWPAN/Thread/thread_extension_bbr.c

@@ -553,6 +553,7 @@ static int thread_pbbr_dua_duplicate_address_detection(int8_t service_id, uint8_
         }
         ipv6_route_delete(route->prefix, route->prefix_len, this->interface_id, NULL, ROUTE_THREAD_PROXIED_DUA_HOST);
     }
+
     return 0;
 }
 
@@ -592,9 +593,18 @@ static int thread_pbbr_bb_ans_cb(int8_t service_id, uint8_t source_address[16],
 
     if ( addr_len < 16|| ml_eid_len < 8 || last_transaction_time_len < 4 ) {
         tr_err("Invalid message");
+        // send confirmation with not acceptable status code
+        if (request_ptr->msg_type == COAP_MSG_TYPE_CONFIRMABLE) {
+            coap_service_response_send(service_id, COAP_REQUEST_OPTIONS_NONE, request_ptr, COAP_MSG_CODE_RESPONSE_NOT_ACCEPTABLE, COAP_CT_OCTET_STREAM, NULL, 0);
+        }
         return 0;
     }
 
+    // when we process unicast b/ba req send confirmation
+    if (request_ptr->msg_type == COAP_MSG_TYPE_CONFIRMABLE) {
+        coap_service_response_send(service_id, COAP_REQUEST_OPTIONS_NONE, request_ptr, COAP_MSG_CODE_RESPONSE_CHANGED, COAP_CT_OCTET_STREAM, NULL, 0);
+    }
+
     if ((thread_pbbr_dua_duplicate_address_detection(service_id, addr_data_ptr, ml_eid_ptr) == 0)) {
         return 0;
     }