Drop forwarding error packet and send back DAO to originating parent

core/net/ipv6/uip6.c

@@ -1207,7 +1207,11 @@ uip_process(uint8_t flag)
       }
 
 #if UIP_CONF_IPV6_RPL
-      rpl_update_header_empty();
+      if(rpl_update_header_empty()) {
+        /* Packet can not be forwarded */
+        PRINTF("RPL Forward Option Error\n");
+        goto drop;
+      }
 #endif /* UIP_CONF_IPV6_RPL */
 
       UIP_IP_BUF->ttl = UIP_IP_BUF->ttl - 1;

core/net/rpl/rpl-dag.c

@@ -93,6 +93,13 @@ rpl_dag_init(void)
   nbr_table_register(rpl_parents, (nbr_table_callback *)nbr_callback);
 }
 /*---------------------------------------------------------------------------*/
+rpl_parent_t *
+rpl_get_parent(uip_lladdr_t *addr)
+{
+  rpl_parent_t *p = nbr_table_get_from_lladdr(rpl_parents, (linkaddr_t *)addr);
+  return p;
+}
+/*---------------------------------------------------------------------------*/
 rpl_rank_t
 rpl_get_parent_rank(uip_lladdr_t *addr)
 {

core/net/rpl/rpl-ext-header.c

@@ -48,6 +48,7 @@
 #include "net/ip/tcpip.h"
 #include "net/ipv6/uip-ds6.h"
 #include "net/rpl/rpl-private.h"
+#include "net/packetbuf.h"
 
 #define DEBUG DEBUG_NONE
 #include "net/ip/uip-debug.h"
@@ -175,12 +176,13 @@ set_rpl_opt(unsigned uip_ext_opt_offset)
   }
 }
 /*---------------------------------------------------------------------------*/
-void
+int
 rpl_update_header_empty(void)
 {
   rpl_instance_t *instance;
   int uip_ext_opt_offset;
   int last_uip_ext_len;
+  rpl_parent_t *parent;
 
   last_uip_ext_len = uip_ext_len;
   uip_ext_len = 0;
@@ -203,12 +205,12 @@ rpl_update_header_empty(void)
     if(UIP_EXT_HDR_OPT_RPL_BUF->opt_len != RPL_HDR_OPT_LEN) {
       PRINTF("RPL: RPL Hop-by-hop option has wrong length\n");
       uip_ext_len = last_uip_ext_len;
-      return;
+      return 0;
     }
     instance = rpl_get_instance(UIP_EXT_HDR_OPT_RPL_BUF->instance);
     if(instance == NULL || !instance->used || !instance->current_dag->joined) {
       PRINTF("RPL: Unable to add hop-by-hop extension header: incorrect instance\n");
-      return;
+      return 0;
     }
     break;
   default:
@@ -216,11 +218,11 @@ rpl_update_header_empty(void)
     if(uip_len + RPL_HOP_BY_HOP_LEN > UIP_BUFSIZE) {
       PRINTF("RPL: Packet too long: impossible to add hop-by-hop option\n");
       uip_ext_len = last_uip_ext_len;
-      return;
+      return 0;
     }
     set_rpl_opt(uip_ext_opt_offset);
     uip_ext_len = last_uip_ext_len + RPL_HOP_BY_HOP_LEN;
-    return;
+    return 0;
   }
 
   switch(UIP_EXT_HDR_OPT_BUF->type) {
@@ -236,6 +238,15 @@ rpl_update_header_empty(void)
       if(uip_ds6_route_lookup(&UIP_IP_BUF->destipaddr) == NULL) {
         UIP_EXT_HDR_OPT_RPL_BUF->flags |= RPL_HDR_OPT_FWD_ERR;
         PRINTF("RPL forwarding error\n");
+        /* We should send back the packet to the originating parent,
+           but it is not feasible yet, so we send a No-Path DAO instead */
+        PRINTF("RPL generate No-Path DAO\n");
+        parent = rpl_get_parent((uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER));
+        if(parent != NULL) {
+          dao_output_target(parent, &UIP_IP_BUF->destipaddr, RPL_ZERO_LIFETIME);
+        }
+        /* Drop packet */
+        return 1;
       }
     } else {
       /* Set the down extension flag correctly as described in Section
@@ -254,11 +265,11 @@ rpl_update_header_empty(void)
     }
 
     uip_ext_len = last_uip_ext_len;
-    return;
+    return 0;
   default:
     PRINTF("RPL: Multi Hop-by-hop options not implemented\n");
     uip_ext_len = last_uip_ext_len;
-    return;
+    return 0;
   }
 }
 /*---------------------------------------------------------------------------*/

core/net/rpl/rpl.h

@@ -240,13 +240,14 @@ int rpl_repair_root(uint8_t instance_id);
 int rpl_set_default_route(rpl_instance_t *instance, uip_ipaddr_t *from);
 rpl_dag_t *rpl_get_any_dag(void);
 rpl_instance_t *rpl_get_instance(uint8_t instance_id);
-void rpl_update_header_empty(void);
+int rpl_update_header_empty(void);
 int rpl_update_header_final(uip_ipaddr_t *addr);
 int rpl_verify_header(int);
 void rpl_insert_header(void);
 void rpl_remove_header(void);
 uint8_t rpl_invert_header(void);
 uip_ipaddr_t *rpl_get_parent_ipaddr(rpl_parent_t *nbr);
+rpl_parent_t *rpl_get_parent(uip_lladdr_t *addr);
 rpl_rank_t rpl_get_parent_rank(uip_lladdr_t *addr);
 uint16_t rpl_get_parent_link_metric(const uip_lladdr_t *addr);
 void rpl_dag_init(void);