uip-nd6: bugfix on address resolution by Neighbor Discovery protocol

nbr_table_update_lladdr() fails to update the lladdr of a nbr with a
new one when the new lladdr is used in nbr_table. This causes
communication errors when NS/NA is employed.

uip_ds6_nbr_update_ll() is introduced to resolve this issue. And
nbr_table_update_lladdr() is removed since it's not used any more.

os/net/ipv6/uip-ds6-nbr.c

@@ -127,6 +127,41 @@ uip_ds6_nbr_rm(uip_ds6_nbr_t *nbr)
   return 0;
 }
 
+/*---------------------------------------------------------------------------*/
+int
+uip_ds6_nbr_update_ll(uip_ds6_nbr_t **nbr_pp, const uip_lladdr_t *new_ll_addr)
+{
+  uip_ds6_nbr_t nbr_backup;
+
+  if(nbr_pp == NULL || new_ll_addr == NULL) {
+    LOG_ERR("%s: invalid argument\n", __func__);
+    return -1;
+  }
+
+  /* make sure new_ll_addr is not used in some other nbr */
+  if(uip_ds6_nbr_ll_lookup(new_ll_addr) != NULL) {
+    LOG_ERR("%s: new_ll_addr, ", __func__);
+    LOG_ERR_LLADDR((const linkaddr_t *)new_ll_addr);
+    LOG_ERR_(", is already used in another nbr\n");
+    return -1;
+  }
+
+  memcpy(&nbr_backup, *nbr_pp, sizeof(uip_ds6_nbr_t));
+  if(uip_ds6_nbr_rm(*nbr_pp) == 0) {
+    LOG_ERR("%s: input nbr cannot be removed\n", __func__);
+    return -1;
+  }
+
+  if((*nbr_pp = uip_ds6_nbr_add(&nbr_backup.ipaddr, new_ll_addr,
+                                nbr_backup.isrouter, nbr_backup.state,
+                                NBR_TABLE_REASON_IPV6_ND, NULL)) == NULL) {
+    LOG_ERR("%s: cannot allocate a new nbr for new_ll_addr\n", __func__);
+    return -1;
+  }
+  memcpy(*nbr_pp, &nbr_backup, sizeof(uip_ds6_nbr_t));
+
+  return 0;
+}
 /*---------------------------------------------------------------------------*/
 const uip_ipaddr_t *
 uip_ds6_nbr_get_ipaddr(const uip_ds6_nbr_t *nbr)

os/net/ipv6/uip-ds6-nbr.h

@@ -90,6 +90,7 @@ uip_ds6_nbr_t *uip_ds6_nbr_add(const uip_ipaddr_t *ipaddr,
                                nbr_table_reason_t reason, void *data);
 int uip_ds6_nbr_rm(uip_ds6_nbr_t *nbr);
 const uip_lladdr_t *uip_ds6_nbr_get_ll(const uip_ds6_nbr_t *nbr);
+int uip_ds6_nbr_update_ll(uip_ds6_nbr_t **nbr, const uip_lladdr_t *new_ll_addr);
 const uip_ipaddr_t *uip_ds6_nbr_get_ipaddr(const uip_ds6_nbr_t *nbr);
 uip_ds6_nbr_t *uip_ds6_nbr_lookup(const uip_ipaddr_t *ipaddr);
 uip_ds6_nbr_t *uip_ds6_nbr_ll_lookup(const uip_lladdr_t *lladdr);

os/net/ipv6/uip-nd6.c

@@ -230,7 +230,9 @@ ns_input(void)
           }
           if(memcmp(&nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET],
               lladdr, UIP_LLADDR_LEN) != 0) {
-            if(nbr_table_update_lladdr((const linkaddr_t *)lladdr, (const linkaddr_t *)&lladdr_aligned, 1) == 0) {
+            if(uip_ds6_nbr_update_ll(&nbr,
+                                     (const uip_lladdr_t *)&lladdr_aligned)
+               < 0) {
               /* failed to update the lladdr */
               goto discard;
             }
@@ -534,7 +536,8 @@ na_input(void)
       if(nd6_opt_llao == NULL || !extract_lladdr_from_llao_aligned(&lladdr_aligned)) {
         goto discard;
       }
-      if(nbr_table_update_lladdr((const linkaddr_t *)lladdr, (const linkaddr_t *)&lladdr_aligned, 1) == 0) {
+      if(uip_ds6_nbr_update_ll(&nbr,
+                               (const uip_lladdr_t *)&lladdr_aligned) < 0) {
         /* failed to update the lladdr */
         goto discard;
       }
@@ -561,7 +564,9 @@ na_input(void)
         if(is_override || !is_llchange || nd6_opt_llao == NULL) {
           if(nd6_opt_llao != NULL && is_llchange) {
             if(!extract_lladdr_from_llao_aligned(&lladdr_aligned) ||
-               nbr_table_update_lladdr((const linkaddr_t *) lladdr, (const linkaddr_t *) &lladdr_aligned, 1) == 0) {
+               uip_ds6_nbr_update_ll(&nbr,
+                                     (const uip_lladdr_t *)&lladdr_aligned)
+               < 0) {
               /* failed to update the lladdr */
               goto discard;
             }
@@ -925,7 +930,8 @@ ra_input(void)
         if(memcmp(&nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET],
                   lladdr, UIP_LLADDR_LEN) != 0) {
           /* change of link layer address */
-          if(nbr_table_update_lladdr((const linkaddr_t *)lladdr, (const linkaddr_t *)&lladdr_aligned, 1) == 0) {
+          if(uip_ds6_nbr_update_ll(&nbr,
+                                   (const uip_lladdr_t *)&lladdr_aligned) < 0) {
             /* failed to update the lladdr */
             goto discard;
           }

os/net/nbr-table.c

@@ -439,39 +439,6 @@ nbr_table_get_lladdr(nbr_table_t *table, const void *item)
   return key != NULL ? &key->lladdr : NULL;
 }
 /*---------------------------------------------------------------------------*/
-/* Update link-layer address of an item */
-int
-nbr_table_update_lladdr(const linkaddr_t *old_addr, const linkaddr_t *new_addr,
-                        int remove_if_duplicate)
-{
-  int index;
-  int new_index;
-  nbr_table_key_t *key;
-  index = index_from_lladdr(old_addr);
-  if(index == -1) {
-    /* Failure to change since there is nothing to change. */
-    return 0;
-  }
-  if((new_index = index_from_lladdr(new_addr)) != -1) {
-    /* check if it is a change or not - do not remove / fail if same */
-    if(new_index == index) {
-      return 1;
-    }
-    /* This new entry already exists - failure! - remove if requested. */
-    if(remove_if_duplicate) {
-      remove_key(key_from_index(index));
-    }
-    return 0;
-  }
-  key = key_from_index(index);
-  /**
-   * Copy the new lladdr into the key - since we know that there is no
-   * conflicting entry.
-   */
-  memcpy(&key->lladdr, new_addr, sizeof(linkaddr_t));
-  return 1;
-}
-/*---------------------------------------------------------------------------*/
 #if DEBUG
 static void
 print_table()

os/net/nbr-table.h

@@ -113,7 +113,6 @@ int nbr_table_unlock(nbr_table_t *table, nbr_table_item_t *item);
 /** \name Neighbor tables: address manipulation */
 /** @{ */
 linkaddr_t *nbr_table_get_lladdr(nbr_table_t *table, const nbr_table_item_t *item);
-int nbr_table_update_lladdr(const linkaddr_t *old_addr, const linkaddr_t *new_addr, int remove_if_duplicate);
 /** @} */
 
 #endif /* NBR_TABLE_H_ */