DIO prefix handler update

Accept prefix update if dio version number is same or higher than parent and time between last DIO from parent is more than 2xIMAX time.

Change-Id: I1336b604f864e11add5d2e85d8724f565f67da5b

Author: Juha Heiskanen

source/RPL/rpl_control.c

@@ -686,13 +686,12 @@ static void rpl_control_process_prefix_options(protocol_interface_info_entry_t *
         uint32_t preferred = common_read_32_bit(ptr + 8);
         const uint8_t *prefix = ptr + 16;
 
-        if (!pref_parent || neighbour == pref_parent) {
+        if (rpl_upward_accept_prefix_update(dodag, neighbour, pref_parent)) {
 
             /* Store prefixes for possible forwarding */
             /* XXX if leaf - don't bother? Or do we want to remember them for
              * when we switch DODAG, as mentioned above?
              */
-
             prefix_entry_t *prefix_entry = rpl_dodag_update_dio_prefix(dodag, prefix, prefix_len, flags, valid, preferred, false, true);
             if (prefix_entry && pref_parent) {
                 rpl_control_process_prefix_option(prefix_entry, cur);

source/RPL/rpl_upward.c

@@ -1845,4 +1845,26 @@ bool rpl_upward_read_dodag_info(const rpl_instance_t *instance, rpl_dodag_info_t
     return true;
 }
 
+bool rpl_upward_accept_prefix_update(const rpl_dodag_t *dodag_info, const rpl_neighbour_t *neighbour, const rpl_neighbour_t *pref_parent)
+{
+    //Accept allways from Pref parent or before it is selected
+    if (!pref_parent || neighbour == pref_parent) {
+        return true;
+    }
+
+    //Accept only same or higher version number
+    if (rpl_dodag_version_compare(neighbour->dodag_version, pref_parent->dodag_version) & (RPL_CMP_EQUAL | RPL_CMP_GREATER)) {
+        //Calculate Time between from last dio from parent and this neighbour
+        //neighbour dio_timestamp >= pref_parent's, because it's a newly-received message
+        uint32_t time_between_parent = neighbour->dio_timestamp - pref_parent->dio_timestamp;
+        uint32_t accepted_time = (uint32_t)dodag_info->dio_timer_params.Imax * 2;
+        //Accept prefix Update If Time from last DIO is more than 2 x Max
+        if (accepted_time < time_between_parent) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 #endif /* HAVE_RPL */

source/RPL/rpl_upward.h

@@ -145,5 +145,6 @@ void rpl_instance_run_parent_selection(rpl_instance_t *instance);
 void rpl_upward_print_instance(rpl_instance_t *instance, route_print_fn_t *print_fn);
 
 bool rpl_upward_read_dodag_info(const rpl_instance_t *instance, struct rpl_dodag_info_t *dodag_info);
+bool rpl_upward_accept_prefix_update(const rpl_dodag_t *dodag_info, const rpl_neighbour_t *neighbour, const rpl_neighbour_t *pref_parent);
 uint16_t rpl_upward_read_dao_target_list_size(const rpl_instance_t *instance, const uint8_t *target_prefix);
 #endif /* RPL_UPWARD_H_ */

test/nanostack/unittest/stub/rpl_upward_stub.c

@@ -456,6 +456,11 @@ bool rpl_upward_read_dodag_info(const rpl_instance_t *instance, rpl_dodag_info_t
     return false;
 }
 
+bool rpl_upward_accept_prefix_update(const rpl_dodag_t *dodag_info, const rpl_neighbour_t *neighbour, const rpl_neighbour_t *pref_parent)
+{
+    return false;
+}
+
 uint16_t rpl_upward_read_dao_target_list_size(const rpl_instance_t *instance, const uint8_t *target_prefix)
 {
     return 0;