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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.

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adamdunkels 2009-03-23 18:10:09 +00:00
parent 39af9b361d
commit d0b969ec5a
1 changed files with 173 additions and 16 deletions
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189
examples/rime/example-multihop.c
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@ -28,7 +28,7 @@
*
* This file is part of the Contiki operating system.
*
* $Id: example-multihop.c,v 1.3 2009/03/12 21:58:21 adamdunkels Exp $
* $Id: example-multihop.c,v 1.4 2009/03/23 18:10:09 adamdunkels Exp $
*/
/**
@ -36,31 +36,162 @@
* Testing the multihop forwarding layer (multihop) in Rime
* \author
* Adam Dunkels <adam@sics.se>
*
*
* This example shows how to use the multihop Rime module, how
* to use the announcement mechanism, how to manage a list
* with the list module, and how to allocate memory with the
* memb module.
*
* The multihop module provides hooks for forwarding packets
* in a multi-hop fashion, but does not implement any routing
* protocol. A routing mechanism must be provided by the
* application or protocol running on top of the multihop
* module. In this case, this example program provides the
* routing mechanism.
*
* The routing mechanism implemented by this example program
* is very simple: it forwards every incoming packet to a
* random neighbor. The program maintains a list of neighbors,
* which it populated through the use of the announcement
* mechanism.
*
* The neighbor list is populated by incoming announcements
* from neighbors. The program maintains a list of neighbors,
* where each entry is allocated from a MEMB() (memory block
* pool). Each neighbor has a timeout so that they do not
* occupy their list entry for too long.
*
* When a packet arrives to the node, the function forward()
* is called by the multihop layer. This function picks a
* random neighbor to send the packet to. The packet is
* forwarded by every node in the network until it reaches its
* final destination (or is discarded in transit due to a
* transmission error or a collision).
*
*/
#include "contiki.h"
#include "net/rime.h"
#include "lib/list.h"
#include "lib/memb.h"
#include "lib/random.h"
#include "dev/button-sensor.h"
#include "dev/leds.h"
#include <stdio.h>
#define CHANNEL 128
struct example_neighbor {
struct example_neighbor *next;
rimeaddr_t addr;
struct ctimer ctimer;
};
#define NEIGHBOR_TIMEOUT 60 * CLOCK_SECOND
#define MAX_NEIGHBORS 16
LIST(neighbor_table);
MEMB(neighbor_mem, struct example_neighbor, MAX_NEIGHBORS);
/*---------------------------------------------------------------------------*/
PROCESS(example_multihop_process, "multihop example");
AUTOSTART_PROCESSES(&example_multihop_process);
/*---------------------------------------------------------------------------*/
/*
* This function is called by the ctimer present in each neighbor
* table entry. The function removes the neighbor from the table
* because it has become too old.
*/
static void
recv(struct multihop_conn *c, rimeaddr_t *sender, rimeaddr_t *prevhop,
remove_neighbor(void *n)
{
struct example_neighbor *e = n;
list_remove(neighbor_table, e);
memb_free(&neighbor_mem, e);
}
/*---------------------------------------------------------------------------*/
/*
* This function is called when an incoming announcement arrives. The
* function checks the neighbor table to see if the neighbor is
* already present in the list. If the neighbor is not present in the
* list, a new neighbor table entry is allocated and is added to the
* neighbor table.
*/
static void
received_announcement(struct announcement *a, rimeaddr_t *from,
uint16_t id, uint16_t value)
{
struct example_neighbor *e;
/* printf("Got announcement from %d.%d, id %d, value %d\n",
from->u8[0], from->u8[1], id, value);*/
/* We received an announcement from a neighbor so we need to update
the neighbor list, or add a new entry to the table. */
for(e = list_head(neighbor_table); e != NULL; e = e->next) {
if(rimeaddr_cmp(from, &e->addr)) {
/* Our neighbor was found, so we update the timeout. */
ctimer_set(&e->ctimer, NEIGHBOR_TIMEOUT, remove_neighbor, e);
return;
}
}
/* The neighbor was not found in the list, so we add a new entry by
allocating memory from the neighbor_mem pool, fill in the
necessary fields, and add it to the list. */
e = memb_alloc(&neighbor_mem);
if(e != NULL) {
rimeaddr_copy(&e->addr, from);
list_add(neighbor_table, e);
ctimer_set(&e->ctimer, NEIGHBOR_TIMEOUT, remove_neighbor, e);
}
}
static struct announcement example_announcement;
/*---------------------------------------------------------------------------*/
/*
* This function is called at the final recepient of the message.
*/
static void
recv(struct multihop_conn *c, const rimeaddr_t *sender,
const rimeaddr_t *prevhop,
uint8_t hops)
{
printf("multihop message received '%s'\n", (char *)packetbuf_dataptr());
}
/*
* This function is called to forward a packet. The function picks a
* random neighbor from the neighbor list and returns its address. The
* multihop layer sends the packet to this address. If no neighbor is
* found, the function returns NULL to signal to the multihop layer
* that the packet should be dropped.
*/
static rimeaddr_t *
forward(struct multihop_conn *c, rimeaddr_t *originator, rimeaddr_t *dest,
rimeaddr_t *prevhop, uint8_t hops)
forward(struct multihop_conn *c,
const rimeaddr_t *originator, const rimeaddr_t *dest,
const rimeaddr_t *prevhop, uint8_t hops)
{
printf("Forwarding message '%s'\n", (char *)packetbuf_dataptr());
/* Find a random neighbor to send to. */
int num, i;
struct example_neighbor *n;
if(list_length(neighbor_table) > 0) {
num = random_rand() % list_length(neighbor_table);
i = 0;
for(n = list_head(neighbor_table); n != NULL && i != num; n = n->next) {
++i;
}
if(n != NULL) {
printf("%d.%d: Forwarding packet to %d.%d (%d in list), hops %d\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
n->addr.u8[0], n->addr.u8[1], num,
packetbuf_attr(PACKETBUF_ATTR_HOPS));
return &n->addr;
}
}
printf("%d.%d: did not find a neighbor to foward to\n",
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1]);
return NULL;
}
static const struct multihop_callbacks multihop_call = {recv, forward};
@ -72,19 +203,45 @@ PROCESS_THREAD(example_multihop_process, ev, data)
PROCESS_BEGIN();
multihop_open(&multihop, 128, &multihop_call);
/* Initialize the memory for the neighbor table entries. */
memb_init(&neighbor_mem);
/* Initialize the list used for the neighbor table. */
list_init(neighbor_table);
/* Open a multihop connection on Rime channel CHANNEL. */
multihop_open(&multihop, CHANNEL, &multihop_call);
/* Register an announcement with the same announcement ID as the
Rime channel we use to open the multihop connection above. */
announcement_register(&example_announcement,
CHANNEL,
0,
received_announcement);
/* Activate the button sensor. We use the button to drive traffic -
when the btton is pressed, a packet is sent. */
button_sensor.activate();
/* Loop forever, send a packet when the button is pressed. */
while(1) {
static struct etimer et;
rimeaddr_t to;
etimer_set(&et, CLOCK_SECOND);
PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));
packetbuf_copyfrom("Hej", 4);
to.u8[0] = 161;
to.u8[1] = 161;
/* Wait until we get a sensor event with the button sensor as data. */
PROCESS_WAIT_EVENT_UNTIL(ev == sensors_event &&
data == &button_sensor);
/* Copy the "Hello" to the packet buffer. */
packetbuf_copyfrom("Hello", 6);
/* Set the Rime address of the final receiver of the packet to
1.1. This is just a dummy value that happens to work nicely in a
netsim simulation (because the default simulation setup creates
one node with address 1.1). */
to.u8[0] = 1;
to.u8[1] = 1;
/* Send the packet. */
multihop_send(&multihop, &to);
}