/*
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* Copyright (c) 2013, Swedish Institute of Computer Science
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* Copyright (c) 2010, Vrije Universiteit Brussel
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*
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* Authors: Simon Duquennoy <simonduq@sics.se>
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* Joris Borms <joris.borms@vub.ac.be>
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*/
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#include "contiki.h"
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#include <stddef.h>
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#include <string.h>
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#include "lib/memb.h"
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#include "lib/list.h"
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#include "net/nbr-table.h"
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/* List of link-layer addresses of the neighbors, used as key in the tables */
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typedef struct nbr_table_key {
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struct nbr_table_key *next;
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rimeaddr_t lladdr;
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} nbr_table_key_t;
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/* For each neighbor, a map of the tables that use the neighbor.
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* As we are using uint8_t, we have a maximum of 8 tables in the system */
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static uint8_t used_map[NBR_TABLE_MAX_NEIGHBORS];
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/* For each neighbor, a map of the tables that lock the neighbor */
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static uint8_t locked_map[NBR_TABLE_MAX_NEIGHBORS];
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/* The maximum number of tables */
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#define MAX_NUM_TABLES 8
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/* A list of pointers to tables in use */
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static struct nbr_table *all_tables[MAX_NUM_TABLES];
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/* The current number of tables */
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static unsigned num_tables;
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/* The neighbor address table */
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MEMB(neighbor_addr_mem, nbr_table_key_t, NBR_TABLE_MAX_NEIGHBORS);
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LIST(nbr_table_keys);
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/*---------------------------------------------------------------------------*/
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/* Get a key from a neighbor index */
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static nbr_table_key_t *
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key_from_index(int index)
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{
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return index != -1 ? &((nbr_table_key_t *)neighbor_addr_mem.mem)[index] : NULL;
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}
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/*---------------------------------------------------------------------------*/
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/* Get an item from its neighbor index */
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static nbr_table_item_t *
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item_from_index(nbr_table_t *table, int index)
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{
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return table != NULL && index != -1 ? (char *)table->data + index * table->item_size : NULL;
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}
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/*---------------------------------------------------------------------------*/
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/* Get the neighbor index of an item */
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static int
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index_from_key(nbr_table_key_t *key)
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{
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return key != NULL ? key - (nbr_table_key_t *)neighbor_addr_mem.mem : -1;
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}
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/*---------------------------------------------------------------------------*/
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/* Get the neighbor index of an item */
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static int
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index_from_item(nbr_table_t *table, nbr_table_item_t *item)
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{
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return table != NULL && item != NULL ? ((int)((char *)item - (char *)table->data)) / table->item_size : -1;
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}
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/*---------------------------------------------------------------------------*/
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/* Get an item from its key */
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static nbr_table_item_t *
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item_from_key(nbr_table_t *table, nbr_table_key_t *key)
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{
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return item_from_index(table, index_from_key(key));
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}
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/*---------------------------------------------------------------------------*/
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/* Get the key af an item */
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static nbr_table_key_t *
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key_from_item(nbr_table_t *table, nbr_table_item_t *item)
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{
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return key_from_index(index_from_item(table, item));
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}
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/*---------------------------------------------------------------------------*/
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/* Get the index of a neighbor from its link-layer address */
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static int
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index_from_lladdr(const rimeaddr_t *lladdr)
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{
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nbr_table_key_t *key;
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/* Allow lladdr-free insertion, useful e.g. for IPv6 ND.
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* Only one such entry is possible at a time, indexed by rimeaddr_null. */
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if(lladdr == NULL) {
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lladdr = &rimeaddr_null;
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}
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key = list_head(nbr_table_keys);
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while(key != NULL) {
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if(lladdr && rimeaddr_cmp(lladdr, &key->lladdr)) {
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return index_from_key(key);
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}
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key = list_item_next(key);
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}
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return -1;
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}
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/*---------------------------------------------------------------------------*/
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/* Get bit from "used" or "locked" bitmap */
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static int
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nbr_get_bit(uint8_t *bitmap, nbr_table_t *table, nbr_table_item_t *item)
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{
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int item_index = index_from_item(table, item);
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if(table != NULL && item_index != -1) {
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return (bitmap[item_index] & (1 << table->index)) != 0;
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} else {
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return 0;
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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/* Set bit in "used" or "locked" bitmap */
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static int
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nbr_set_bit(uint8_t *bitmap, nbr_table_t *table, nbr_table_item_t *item, int value)
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{
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int item_index = index_from_item(table, item);
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if(table != NULL && item_index != -1) {
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if(value) {
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bitmap[item_index] |= 1 << table->index;
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} else {
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bitmap[item_index] &= ~(1 << table->index);
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}
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return 1;
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} else {
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return 0;
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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static nbr_table_key_t *
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nbr_table_allocate(void)
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{
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nbr_table_key_t *key;
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int least_used_count = 0;
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nbr_table_key_t *least_used_key = NULL;
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key = memb_alloc(&neighbor_addr_mem);
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if(key != NULL) {
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return key;
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} else { /* No more space, try to free a neighbor.
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* The replacement policy is the following: remove neighbor that is:
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* (1) not locked
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* (2) used by fewest tables
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* (3) oldest (the list is ordered by insertion time)
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* */
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/* Get item from first key */
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key = list_head(nbr_table_keys);
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while(key != NULL) {
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int item_index = index_from_key(key);
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int locked = locked_map[item_index];
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/* Never delete a locked item */
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if(!locked) {
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int used = used_map[item_index];
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int used_count = 0;
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/* Count how many tables are using this item */
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while(used != 0) {
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if((used & 1) == 1) {
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used_count++;
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}
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used >>= 1;
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}
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/* Find least used item */
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if(least_used_key == NULL || used_count < least_used_count) {
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least_used_key = key;
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least_used_count = used_count;
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if(used_count == 0) { /* We won't find any least used item */
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break;
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}
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}
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}
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key = list_item_next(key);
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}
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if(least_used_key == NULL) {
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/* We haven't found any unlocked item, allocation fails */
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return NULL;
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} else {
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/* Reuse least used item */
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int i;
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for(i = 0; i<MAX_NUM_TABLES; i++) {
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if(all_tables[i] != NULL && all_tables[i]->callback != NULL) {
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/* Call table callback for each table that uses this item */
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nbr_table_item_t *removed_item = item_from_key(all_tables[i], least_used_key);
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if(nbr_get_bit(used_map, all_tables[i], removed_item) == 1) {
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all_tables[i]->callback(removed_item);
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}
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}
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}
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/* Empty used map */
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used_map[index_from_key(least_used_key)] = 0;
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/* Remove neighbor from list */
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list_remove(nbr_table_keys, least_used_key);
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/* Return associated key */
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return least_used_key;
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}
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}
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}
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/*---------------------------------------------------------------------------*/
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/* Register a new neighbor table. To be used at initialization by modules
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* using a neighbor table */
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int
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nbr_table_register(nbr_table_t *table, nbr_table_callback *callback)
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{
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if(num_tables < MAX_NUM_TABLES) {
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table->index = num_tables++;
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table->callback = callback;
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all_tables[table->index] = table;
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return 1;
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} else {
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/* Maximum number of tables exceeded */
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return 0;
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}
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}
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/*---------------------------------------------------------------------------*/
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/* Returns the first item of the current table */
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nbr_table_item_t *
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nbr_table_head(nbr_table_t *table)
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{
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/* Get item from first key */
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nbr_table_item_t *item = item_from_key(table, list_head(nbr_table_keys));
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/* Item is the first neighbor, now check is it is in the current table */
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if(nbr_get_bit(used_map, table, item)) {
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return item;
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} else {
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return nbr_table_next(table, item);
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}
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}
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/*---------------------------------------------------------------------------*/
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/* Iterates over the current table */
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nbr_table_item_t *
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nbr_table_next(nbr_table_t *table, nbr_table_item_t *item)
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{
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do {
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void *key = key_from_item(table, item);
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key = list_item_next(key);
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/* Loop until the next item is in the current table */
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item = item_from_key(table, key);
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} while(item && !nbr_get_bit(used_map, table, item));
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return item;
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}
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/*---------------------------------------------------------------------------*/
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/* Add a neighbor indexed with its link-layer address */
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nbr_table_item_t *
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nbr_table_add_lladdr(nbr_table_t *table, const rimeaddr_t *lladdr)
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{
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int index;
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nbr_table_item_t *item;
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nbr_table_key_t *key;
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/* Allow lladdr-free insertion, useful e.g. for IPv6 ND.
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* Only one such entry is possible at a time, indexed by rimeaddr_null. */
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if(lladdr == NULL) {
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lladdr = &rimeaddr_null;
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}
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if((index = index_from_lladdr(lladdr)) == -1) {
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/* Neighbor not yet in table, let's try to allocate one */
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key = nbr_table_allocate();
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/* No space available for new entry */
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if(key == NULL) {
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return NULL;
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}
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/* Add neighbor to list */
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list_add(nbr_table_keys, key);
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/* Get index from newly allocated neighbor */
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index = index_from_key(key);
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/* Set link-layer address */
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rimeaddr_copy(&key->lladdr, lladdr);
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}
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/* Get item in the current table */
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item = item_from_index(table, index);
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/* Initialize item data and set "used" bit */
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memset(item, 0, table->item_size);
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nbr_set_bit(used_map, table, item, 1);
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return item;
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}
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/*---------------------------------------------------------------------------*/
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/* Get an item from its link-layer address */
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void *
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nbr_table_get_from_lladdr(nbr_table_t *table, const rimeaddr_t *lladdr)
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{
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void *item = item_from_index(table, index_from_lladdr(lladdr));
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return nbr_get_bit(used_map, table, item) ? item : NULL;
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}
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/*---------------------------------------------------------------------------*/
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/* Removes a neighbor from the current table (unset "used" bit) */
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int
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nbr_table_remove(nbr_table_t *table, void *item)
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{
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int ret = nbr_set_bit(used_map, table, item, 0);
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nbr_set_bit(locked_map, table, item, 0);
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return ret;
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}
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/*---------------------------------------------------------------------------*/
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/* Lock a neighbor for the current table (set "locked" bit) */
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int
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nbr_table_lock(nbr_table_t *table, void *item)
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{
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return nbr_set_bit(locked_map, table, item, 1);
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}
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/*---------------------------------------------------------------------------*/
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/* Release the lock on a neighbor for the current table (unset "locked" bit) */
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int
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nbr_table_unlock(nbr_table_t *table, void *item)
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{
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return nbr_set_bit(locked_map, table, item, 0);
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}
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/*---------------------------------------------------------------------------*/
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/* Get link-layer address of an item */
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rimeaddr_t *
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nbr_table_get_lladdr(nbr_table_t *table, void *item)
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{
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nbr_table_key_t *key = key_from_item(table, item);
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return key != NULL ? &key->lladdr : NULL;
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}
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