Rewrote the multihop example to better show how to use the multihop layer. Now also shows how to use the memb, list, and annoncement mechanisms.
adamdunkels
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39af9b361d
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d0b969ec5a
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@ -28,7 +28,7 @@
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*
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* This file is part of the Contiki operating system.
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*
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* $Id: example-multihop.c,v 1.3 2009/03/12 21:58:21 adamdunkels Exp $
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* $Id: example-multihop.c,v 1.4 2009/03/23 18:10:09 adamdunkels Exp $
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*/
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/**
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@ -36,31 +36,162 @@
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* Testing the multihop forwarding layer (multihop) in Rime
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* \author
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* Adam Dunkels <adam@sics.se>
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*
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*
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* This example shows how to use the multihop Rime module, how
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* to use the announcement mechanism, how to manage a list
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* with the list module, and how to allocate memory with the
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* memb module.
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*
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* The multihop module provides hooks for forwarding packets
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* in a multi-hop fashion, but does not implement any routing
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* protocol. A routing mechanism must be provided by the
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* application or protocol running on top of the multihop
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* module. In this case, this example program provides the
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* routing mechanism.
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*
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* The routing mechanism implemented by this example program
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* is very simple: it forwards every incoming packet to a
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* random neighbor. The program maintains a list of neighbors,
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* which it populated through the use of the announcement
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* mechanism.
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*
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* The neighbor list is populated by incoming announcements
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* from neighbors. The program maintains a list of neighbors,
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* where each entry is allocated from a MEMB() (memory block
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* pool). Each neighbor has a timeout so that they do not
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* occupy their list entry for too long.
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*
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* When a packet arrives to the node, the function forward()
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* is called by the multihop layer. This function picks a
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* random neighbor to send the packet to. The packet is
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* forwarded by every node in the network until it reaches its
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* final destination (or is discarded in transit due to a
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* transmission error or a collision).
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*
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*/
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#include "contiki.h"
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#include "net/rime.h"
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#include "lib/list.h"
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#include "lib/memb.h"
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#include "lib/random.h"
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#include "dev/button-sensor.h"
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#include "dev/leds.h"
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#include <stdio.h>
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#define CHANNEL 128
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struct example_neighbor {
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struct example_neighbor *next;
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rimeaddr_t addr;
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struct ctimer ctimer;
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};
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#define NEIGHBOR_TIMEOUT 60 * CLOCK_SECOND
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#define MAX_NEIGHBORS 16
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LIST(neighbor_table);
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MEMB(neighbor_mem, struct example_neighbor, MAX_NEIGHBORS);
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/*---------------------------------------------------------------------------*/
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PROCESS(example_multihop_process, "multihop example");
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AUTOSTART_PROCESSES(&example_multihop_process);
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/*---------------------------------------------------------------------------*/
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/*
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* This function is called by the ctimer present in each neighbor
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* table entry. The function removes the neighbor from the table
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* because it has become too old.
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*/
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static void
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recv(struct multihop_conn *c, rimeaddr_t *sender, rimeaddr_t *prevhop,
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remove_neighbor(void *n)
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{
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struct example_neighbor *e = n;
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list_remove(neighbor_table, e);
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memb_free(&neighbor_mem, e);
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}
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/*---------------------------------------------------------------------------*/
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/*
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* This function is called when an incoming announcement arrives. The
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* function checks the neighbor table to see if the neighbor is
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* already present in the list. If the neighbor is not present in the
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* list, a new neighbor table entry is allocated and is added to the
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* neighbor table.
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*/
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static void
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received_announcement(struct announcement *a, rimeaddr_t *from,
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uint16_t id, uint16_t value)
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{
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struct example_neighbor *e;
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/* printf("Got announcement from %d.%d, id %d, value %d\n",
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from->u8[0], from->u8[1], id, value);*/
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/* We received an announcement from a neighbor so we need to update
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the neighbor list, or add a new entry to the table. */
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for(e = list_head(neighbor_table); e != NULL; e = e->next) {
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if(rimeaddr_cmp(from, &e->addr)) {
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/* Our neighbor was found, so we update the timeout. */
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ctimer_set(&e->ctimer, NEIGHBOR_TIMEOUT, remove_neighbor, e);
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return;
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}
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}
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/* The neighbor was not found in the list, so we add a new entry by
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allocating memory from the neighbor_mem pool, fill in the
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necessary fields, and add it to the list. */
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e = memb_alloc(&neighbor_mem);
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if(e != NULL) {
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rimeaddr_copy(&e->addr, from);
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list_add(neighbor_table, e);
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ctimer_set(&e->ctimer, NEIGHBOR_TIMEOUT, remove_neighbor, e);
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}
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}
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static struct announcement example_announcement;
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/*---------------------------------------------------------------------------*/
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/*
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* This function is called at the final recepient of the message.
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*/
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static void
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recv(struct multihop_conn *c, const rimeaddr_t *sender,
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const rimeaddr_t *prevhop,
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uint8_t hops)
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{
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printf("multihop message received '%s'\n", (char *)packetbuf_dataptr());
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}
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/*
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* This function is called to forward a packet. The function picks a
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* random neighbor from the neighbor list and returns its address. The
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* multihop layer sends the packet to this address. If no neighbor is
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* found, the function returns NULL to signal to the multihop layer
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* that the packet should be dropped.
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*/
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static rimeaddr_t *
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forward(struct multihop_conn *c, rimeaddr_t *originator, rimeaddr_t *dest,
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rimeaddr_t *prevhop, uint8_t hops)
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forward(struct multihop_conn *c,
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const rimeaddr_t *originator, const rimeaddr_t *dest,
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const rimeaddr_t *prevhop, uint8_t hops)
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{
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printf("Forwarding message '%s'\n", (char *)packetbuf_dataptr());
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/* Find a random neighbor to send to. */
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int num, i;
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struct example_neighbor *n;
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if(list_length(neighbor_table) > 0) {
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num = random_rand() % list_length(neighbor_table);
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i = 0;
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for(n = list_head(neighbor_table); n != NULL && i != num; n = n->next) {
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++i;
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}
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if(n != NULL) {
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printf("%d.%d: Forwarding packet to %d.%d (%d in list), hops %d\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
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n->addr.u8[0], n->addr.u8[1], num,
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packetbuf_attr(PACKETBUF_ATTR_HOPS));
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return &n->addr;
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}
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}
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printf("%d.%d: did not find a neighbor to foward to\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1]);
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return NULL;
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}
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static const struct multihop_callbacks multihop_call = {recv, forward};
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@ -72,19 +203,45 @@ PROCESS_THREAD(example_multihop_process, ev, data)
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PROCESS_BEGIN();
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multihop_open(&multihop, 128, &multihop_call);
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/* Initialize the memory for the neighbor table entries. */
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memb_init(&neighbor_mem);
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/* Initialize the list used for the neighbor table. */
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list_init(neighbor_table);
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/* Open a multihop connection on Rime channel CHANNEL. */
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multihop_open(&multihop, CHANNEL, &multihop_call);
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/* Register an announcement with the same announcement ID as the
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Rime channel we use to open the multihop connection above. */
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announcement_register(&example_announcement,
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CHANNEL,
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0,
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received_announcement);
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/* Activate the button sensor. We use the button to drive traffic -
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when the btton is pressed, a packet is sent. */
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button_sensor.activate();
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/* Loop forever, send a packet when the button is pressed. */
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while(1) {
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static struct etimer et;
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rimeaddr_t to;
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etimer_set(&et, CLOCK_SECOND);
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PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));
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packetbuf_copyfrom("Hej", 4);
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to.u8[0] = 161;
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to.u8[1] = 161;
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/* Wait until we get a sensor event with the button sensor as data. */
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PROCESS_WAIT_EVENT_UNTIL(ev == sensors_event &&
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data == &button_sensor);
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/* Copy the "Hello" to the packet buffer. */
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packetbuf_copyfrom("Hello", 6);
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/* Set the Rime address of the final receiver of the packet to
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1.1. This is just a dummy value that happens to work nicely in a
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netsim simulation (because the default simulation setup creates
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one node with address 1.1). */
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to.u8[0] = 1;
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to.u8[1] = 1;
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/* Send the packet. */
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multihop_send(&multihop, &to);
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}
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