From 8afe3fb9b79c6b39130e52f1188c4900557e3154 Mon Sep 17 00:00:00 2001
From: Joakim Eriksson <joakime@sics.se>
Date: Wed, 23 Sep 2015 09:12:35 +0200
Subject: [PATCH] fixed so that DAO NACK now is either for the path or for RPL
 root - if from root then do not try to switch parent since that will not help

---
 core/net/rpl/rpl-icmp6.c   | 10 +++++++---
 core/net/rpl/rpl-mrhof.c   |  5 ++++-
 core/net/rpl/rpl-private.h |  1 +
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/core/net/rpl/rpl-icmp6.c b/core/net/rpl/rpl-icmp6.c
index 6ff0dcfee..0851cd9a2 100644
--- a/core/net/rpl/rpl-icmp6.c
+++ b/core/net/rpl/rpl-icmp6.c
@@ -663,6 +663,7 @@ dao_input(void)
   int learned_from;
   rpl_parent_t *parent;
   uip_ds6_nbr_t *nbr;
+  int is_root;
 
   prefixlen = 0;
   parent = NULL;
@@ -695,6 +696,8 @@ dao_input(void)
   sequence = buffer[pos++];
 
   dag = instance->current_dag;
+  is_root = (dag->rank == ROOT_RANK(instance));
+
   /* Is the DAG ID present? */
   if(flags & RPL_DAO_D_FLAG) {
     if(memcmp(&dag->dag_id, &buffer[pos], sizeof(dag->dag_id))) {
@@ -829,7 +832,8 @@ dao_input(void)
     if(flags & RPL_DAO_K_FLAG) {
       /* signal the failure to add the node */
       dao_ack_output(instance, &dao_sender_addr, sequence,
-             RPL_DAO_ACK_UNABLE_TO_ACCEPT);
+		     is_root ? RPL_DAO_ACK_UNABLE_TO_ACCEPT_ROOT :
+		     RPL_DAO_ACK_UNABLE_TO_ACCEPT);
     }
     goto discard;
   }
@@ -838,11 +842,11 @@ dao_input(void)
   if(rep == NULL) {
     RPL_STAT(rpl_stats.mem_overflows++);
     PRINTF("RPL: Could not add a route after receiving a DAO\n");
-
     if(flags & RPL_DAO_K_FLAG) {
       /* signal the failure to add the node */
       dao_ack_output(instance, &dao_sender_addr, sequence,
-             RPL_DAO_ACK_UNABLE_TO_ACCEPT);
+		     is_root ? RPL_DAO_ACK_UNABLE_TO_ACCEPT_ROOT :
+		     RPL_DAO_ACK_UNABLE_TO_ACCEPT);
     }
     goto discard;
   }
diff --git a/core/net/rpl/rpl-mrhof.c b/core/net/rpl/rpl-mrhof.c
index acf2b1d54..6da2ec304 100644
--- a/core/net/rpl/rpl-mrhof.c
+++ b/core/net/rpl/rpl-mrhof.c
@@ -122,8 +122,11 @@ reset(rpl_dag_t *dag)
 static void
 dao_ack_callback(rpl_parent_t *p, int status)
 {
+  if(status == RPL_DAO_ACK_UNABLE_TO_ACCEPT_ROOT) {
+    return;
+  }
   /* here we need to handle failed DAO's and other stuff */
-  PRINTF("RPL: MRHOF - DAO ACK received with status: %d", status);
+  PRINTF("RPL: MRHOF - DAO ACK received with status: %d\n", status);
   if(status >= RPL_DAO_ACK_UNABLE_TO_ACCEPT) {
     /* punish the ETX as if this was 10 packets lost */
     neighbor_link_callback(p, MAC_TX_OK, 10);
diff --git a/core/net/rpl/rpl-private.h b/core/net/rpl/rpl-private.h
index 017efb474..161cdc532 100644
--- a/core/net/rpl/rpl-private.h
+++ b/core/net/rpl/rpl-private.h
@@ -94,6 +94,7 @@
 #define RPL_DAO_ACK_UNCONDITIONAL_ACCEPT 0
 #define RPL_DAO_ACK_ACCEPT               1   /* 1 - 127 is OK but not good */
 #define RPL_DAO_ACK_UNABLE_TO_ACCEPT     128 /* >127 is fail */
+#define RPL_DAO_ACK_UNABLE_TO_ACCEPT_ROOT 255 /* root can not accept */
 
 #define RPL_DAO_ACK_TIMEOUT              -1