Replaced ROOT_RANK with a macro that allows for other min_hoprankinc parameters than the default. Also made some minor style improvements.

core/net/rpl/rpl-dag.c

@@ -179,7 +179,6 @@ rpl_set_root(uip_ipaddr_t *dag_id)
   dag->version = version + 1;
   dag->grounded = RPL_GROUNDED;
   dag->mop = RPL_MOP_DEFAULT;
-  dag->rank = ROOT_RANK;
   dag->of = &RPL_OF;
   dag->preferred_parent = NULL;
   dag->dtsn_out = 1; /* Trigger DAOs from the beginning. */
@@ -195,6 +194,8 @@ rpl_set_root(uip_ipaddr_t *dag_id)
   dag->default_lifetime = DEFAULT_RPL_DEF_LIFETIME;
   dag->lifetime_unit = DEFAULT_RPL_LIFETIME_UNIT;
 
+  dag->rank = ROOT_RANK(dag);
+
   dag->of->update_metric_container(dag);
 
   PRINTF("RPL: Node set to be a DAG root with DAG ID ");
@@ -555,7 +556,7 @@ global_repair(uip_ipaddr_t *from, rpl_dag_t *dag, rpl_dio_t *dio)
 int
 rpl_repair_dag(rpl_dag_t *dag)
 {
-  if(dag->rank == ROOT_RANK) {
+  if(dag->rank == ROOT_RANK(dag)) {
     dag->version++;
     dag->dtsn_out = 1;
     rpl_reset_dio_timer(dag, 1);
@@ -673,7 +674,7 @@ rpl_process_dio(uip_ipaddr_t *from, rpl_dio_t *dio)
   }
 
   if(dio->version > dag->version) {
-    if(dag->rank == ROOT_RANK) {
+    if(dag->rank == ROOT_RANK(dag)) {
       PRINTF("RPL: Root received inconsistent DIO version number\n");
       dag->version = dio->version + 1;
       rpl_reset_dio_timer(dag, 1);
@@ -690,9 +691,13 @@ rpl_process_dio(uip_ipaddr_t *from, rpl_dio_t *dio)
 
   if(dio->rank == INFINITE_RANK) {
     rpl_reset_dio_timer(dag, 1);
+  } else if(dio->rank < ROOT_RANK(dag)) {
+    PRINTF("RPL: Ignoring DIO with too low rank: %u\n",
+           (unsigned)dio->rank);
+    return;
   }
 
-  if(dag->rank == ROOT_RANK) {
+  if(dag->rank == ROOT_RANK(dag)) {
     if(dio->rank != INFINITE_RANK) {
       dag->dio_counter++;
     }

core/net/rpl/rpl-of-etx.c

@@ -87,8 +87,6 @@ rpl_of_t rpl_of_etx = {
 typedef uint16_t rpl_etx_t;
 #define MAX_ETX 65535
 
-static rpl_etx_t min_path_cost = MAX_ETX;
-
 static uint16_t
 calculate_etx(rpl_parent_t *p)
 {
@@ -98,18 +96,11 @@ calculate_etx(rpl_parent_t *p)
 static void
 reset(rpl_dag_t *dag)
 {
-  min_path_cost = MAX_ETX;
 }
 
 static void
 parent_state_callback(rpl_parent_t *parent, int known, int etx)
 {
-  if(!known) {
-    if(RPL_PARENT_COUNT(parent->dag) == 1) {
-      /* Our last parent has disappeared, set the path ETX to INFINITE_RANK. */
-      min_path_cost = INFINITE_RANK;
-    }
-  }
 }
 
 static rpl_rank_t
@@ -156,7 +147,7 @@ best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
   dag = p1->dag; /* Both parents must be in the same DAG. */
 
   min_diff = RPL_DAG_MC_ETX_DIVISOR / 
-                           PARENT_SWITCH_THRESHOLD_DIV;
+             PARENT_SWITCH_THRESHOLD_DIV;
 
   p1_etx = calculate_etx(p1);
   p2_etx = calculate_etx(p2);
@@ -171,11 +162,7 @@ best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
     return dag->preferred_parent;
   }
 
-  if(p1_etx < p2_etx) {
+  return p1_etx < p2_etx ? p1 : p2;
-    return p1;
-  }
-
-  return p2;
 }
 
 static void
@@ -186,7 +173,7 @@ update_metric_container(rpl_dag_t *dag)
   dag->mc.aggr = RPL_DAG_MC_AGGR_ADDITIVE;
   dag->mc.prec = 0;
   dag->mc.length = sizeof(dag->mc.etx.etx);
-  if(dag->rank == ROOT_RANK) {
+  if(dag->rank == ROOT_RANK(dag)) {
     dag->mc.etx.etx = 0;
   } else {
     dag->mc.etx.etx = calculate_etx(dag->preferred_parent);

core/net/rpl/rpl-private.h

@@ -119,17 +119,17 @@
 
 #define DAG_RANK(fixpt_rank, dag)	((fixpt_rank) / (dag)->min_hoprankinc)
 
-/* Rank of a node outside the LLN. */
+/* Rank of a virtual root node that coordinates DAG root nodes. */
 #define BASE_RANK                       0
 
 /* Rank of a root node. */
-#define ROOT_RANK                       DEFAULT_MIN_HOPRANKINC
+#define ROOT_RANK(dag)                  (dag)->min_hoprankinc
 
 #define INFINITE_RANK                   0xffff
 
 /* Represents 2^n ms. */
-/* Default alue according to the specification is 3 which
+/* Default value according to the specification is 3 which
-   means 8 milliseconds - this is not a reasonable value if
+   means 8 milliseconds, but that is an unreasonable value if
    using power-saving / duty-cycling    */
 #define DEFAULT_DIO_INTERVAL_MIN        12