/*
|
* Copyright (c) 2010, Swedish Institute of Computer Science.
|
* All rights reserved.
|
*
|
* Redistribution and use in source and binary forms, with or without
|
* modification, are permitted provided that the following conditions
|
* are met:
|
* 1. Redistributions of source code must retain the above copyright
|
* notice, this list of conditions and the following disclaimer.
|
* 2. Redistributions in binary form must reproduce the above copyright
|
* notice, this list of conditions and the following disclaimer in the
|
* documentation and/or other materials provided with the distribution.
|
* 3. Neither the name of the Institute nor the names of its contributors
|
* may be used to endorse or promote products derived from this software
|
* without specific prior written permission.
|
*
|
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
* SUCH DAMAGE.
|
*
|
* This file is part of the Contiki operating system.
|
*
|
*/
|
|
/**
|
* \file
|
* A Carrier Sense Multiple Access (CSMA) MAC layer
|
* \author
|
* Adam Dunkels <adam@sics.se>
|
*/
|
|
#include "net/mac/csma.h"
|
#include "net/packetbuf.h"
|
#include "net/queuebuf.h"
|
|
#include "sys/ctimer.h"
|
#include "sys/clock.h"
|
|
#include "lib/random.h"
|
|
#include "net/netstack.h"
|
|
#include "lib/list.h"
|
#include "lib/memb.h"
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#define DEBUG 0
|
#if DEBUG
|
#include <stdio.h>
|
#define PRINTF(...) printf(__VA_ARGS__)
|
#else /* DEBUG */
|
#define PRINTF(...)
|
#endif /* DEBUG */
|
|
#ifndef CSMA_MAX_MAC_TRANSMISSIONS
|
#ifdef CSMA_CONF_MAX_MAC_TRANSMISSIONS
|
#define CSMA_MAX_MAC_TRANSMISSIONS CSMA_CONF_MAX_MAC_TRANSMISSIONS
|
#else
|
#define CSMA_MAX_MAC_TRANSMISSIONS 3
|
#endif /* CSMA_CONF_MAX_MAC_TRANSMISSIONS */
|
#endif /* CSMA_MAX_MAC_TRANSMISSIONS */
|
|
#if CSMA_MAX_MAC_TRANSMISSIONS < 1
|
#error CSMA_CONF_MAX_MAC_TRANSMISSIONS must be at least 1.
|
#error Change CSMA_CONF_MAX_MAC_TRANSMISSIONS in contiki-conf.h or in your Makefile.
|
#endif /* CSMA_CONF_MAX_MAC_TRANSMISSIONS < 1 */
|
|
/* Packet metadata */
|
struct qbuf_metadata {
|
mac_callback_t sent;
|
void *cptr;
|
uint8_t max_transmissions;
|
};
|
|
/* Every neighbor has its own packet queue */
|
struct neighbor_queue {
|
struct neighbor_queue *next;
|
rimeaddr_t addr;
|
struct ctimer transmit_timer;
|
uint8_t transmissions;
|
uint8_t collisions, deferrals;
|
LIST_STRUCT(queued_packet_list);
|
};
|
|
/* The maximum number of co-existing neighbor queues */
|
#ifdef CSMA_CONF_MAX_NEIGHBOR_QUEUES
|
#define CSMA_MAX_NEIGHBOR_QUEUES CSMA_CONF_MAX_NEIGHBOR_QUEUES
|
#else
|
#define CSMA_MAX_NEIGHBOR_QUEUES 2
|
#endif /* CSMA_CONF_MAX_NEIGHBOR_QUEUES */
|
|
#define MAX_QUEUED_PACKETS QUEUEBUF_NUM
|
MEMB(neighbor_memb, struct neighbor_queue, CSMA_MAX_NEIGHBOR_QUEUES);
|
MEMB(packet_memb, struct rdc_buf_list, MAX_QUEUED_PACKETS);
|
MEMB(metadata_memb, struct qbuf_metadata, MAX_QUEUED_PACKETS);
|
LIST(neighbor_list);
|
|
static void packet_sent(void *ptr, int status, int num_transmissions);
|
static void transmit_packet_list(void *ptr);
|
|
/*---------------------------------------------------------------------------*/
|
static struct neighbor_queue *
|
neighbor_queue_from_addr(const rimeaddr_t *addr)
|
{
|
struct neighbor_queue *n = list_head(neighbor_list);
|
while(n != NULL) {
|
if(rimeaddr_cmp(&n->addr, addr)) {
|
return n;
|
}
|
n = list_item_next(n);
|
}
|
return NULL;
|
}
|
/*---------------------------------------------------------------------------*/
|
static clock_time_t
|
default_timebase(void)
|
{
|
clock_time_t time;
|
/* The retransmission time must be proportional to the channel
|
check interval of the underlying radio duty cycling layer. */
|
time = NETSTACK_RDC.channel_check_interval();
|
|
/* If the radio duty cycle has no channel check interval (i.e., it
|
does not turn the radio off), we make the retransmission time
|
proportional to the configured MAC channel check rate. */
|
if(time == 0) {
|
time = CLOCK_SECOND / NETSTACK_RDC_CHANNEL_CHECK_RATE;
|
}
|
return time;
|
}
|
/*---------------------------------------------------------------------------*/
|
static void
|
transmit_packet_list(void *ptr)
|
{
|
struct neighbor_queue *n = ptr;
|
if(n) {
|
struct rdc_buf_list *q = list_head(n->queued_packet_list);
|
if(q != NULL) {
|
PRINTF("csma: preparing number %d %p, queue len %d\n", n->transmissions, q,
|
list_length(n->queued_packet_list));
|
/* Send packets in the neighbor's list */
|
NETSTACK_RDC.send_list(packet_sent, n, q);
|
}
|
}
|
}
|
/*---------------------------------------------------------------------------*/
|
static void
|
free_packet(struct neighbor_queue *n, struct rdc_buf_list *p)
|
{
|
if(p != NULL) {
|
/* Remove packet from list and deallocate */
|
list_remove(n->queued_packet_list, p);
|
|
queuebuf_free(p->buf);
|
memb_free(&metadata_memb, p->ptr);
|
memb_free(&packet_memb, p);
|
PRINTF("csma: free_queued_packet, queue length %d\n",
|
list_length(n->queued_packet_list));
|
if(list_head(n->queued_packet_list) != NULL) {
|
/* There is a next packet. We reset current tx information */
|
n->transmissions = 0;
|
n->collisions = 0;
|
n->deferrals = 0;
|
/* Set a timer for next transmissions */
|
ctimer_set(&n->transmit_timer, default_timebase(),
|
transmit_packet_list, n);
|
} else {
|
/* This was the last packet in the queue, we free the neighbor */
|
ctimer_stop(&n->transmit_timer);
|
list_remove(neighbor_list, n);
|
memb_free(&neighbor_memb, n);
|
}
|
}
|
}
|
/*---------------------------------------------------------------------------*/
|
static void
|
packet_sent(void *ptr, int status, int num_transmissions)
|
{
|
struct neighbor_queue *n;
|
struct rdc_buf_list *q;
|
struct qbuf_metadata *metadata;
|
clock_time_t time = 0;
|
mac_callback_t sent;
|
void *cptr;
|
int num_tx;
|
int backoff_transmissions;
|
|
n = ptr;
|
if(n == NULL) {
|
return;
|
}
|
switch(status) {
|
case MAC_TX_OK:
|
case MAC_TX_NOACK:
|
n->transmissions++;
|
break;
|
case MAC_TX_COLLISION:
|
n->collisions++;
|
break;
|
case MAC_TX_DEFERRED:
|
n->deferrals++;
|
break;
|
}
|
|
for(q = list_head(n->queued_packet_list);
|
q != NULL; q = list_item_next(q)) {
|
if(queuebuf_attr(q->buf, PACKETBUF_ATTR_MAC_SEQNO) ==
|
packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO)) {
|
break;
|
}
|
}
|
|
if(q != NULL) {
|
metadata = (struct qbuf_metadata *)q->ptr;
|
|
if(metadata != NULL) {
|
sent = metadata->sent;
|
cptr = metadata->cptr;
|
num_tx = n->transmissions;
|
if(status == MAC_TX_COLLISION ||
|
status == MAC_TX_NOACK) {
|
|
/* If the transmission was not performed because of a
|
collision or noack, we must retransmit the packet. */
|
|
switch(status) {
|
case MAC_TX_COLLISION:
|
PRINTF("csma: rexmit collision %d\n", n->transmissions);
|
break;
|
case MAC_TX_NOACK:
|
PRINTF("csma: rexmit noack %d\n", n->transmissions);
|
break;
|
default:
|
PRINTF("csma: rexmit err %d, %d\n", status, n->transmissions);
|
}
|
|
/* The retransmission time must be proportional to the channel
|
check interval of the underlying radio duty cycling layer. */
|
time = default_timebase();
|
|
/* The retransmission time uses a linear backoff so that the
|
interval between the transmissions increase with each
|
retransmit. */
|
backoff_transmissions = n->transmissions + 1;
|
|
/* Clamp the number of backoffs so that we don't get a too long
|
timeout here, since that will delay all packets in the
|
queue. */
|
if(backoff_transmissions > 3) {
|
backoff_transmissions = 3;
|
}
|
|
time = time + (random_rand() % (backoff_transmissions * time));
|
|
if(n->transmissions < metadata->max_transmissions) {
|
PRINTF("csma: retransmitting with time %lu %p\n", time, q);
|
ctimer_set(&n->transmit_timer, time,
|
transmit_packet_list, n);
|
/* This is needed to correctly attribute energy that we spent
|
transmitting this packet. */
|
queuebuf_update_attr_from_packetbuf(q->buf);
|
} else {
|
PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
|
status, n->transmissions, n->collisions);
|
free_packet(n, q);
|
mac_call_sent_callback(sent, cptr, status, num_tx);
|
}
|
} else {
|
if(status == MAC_TX_OK) {
|
PRINTF("csma: rexmit ok %d\n", n->transmissions);
|
} else {
|
PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
|
}
|
free_packet(n, q);
|
mac_call_sent_callback(sent, cptr, status, num_tx);
|
}
|
}
|
}
|
}
|
/*---------------------------------------------------------------------------*/
|
static void
|
send_packet(mac_callback_t sent, void *ptr)
|
{
|
struct rdc_buf_list *q;
|
struct neighbor_queue *n;
|
static uint16_t seqno;
|
const rimeaddr_t *addr = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
|
|
if(seqno == 0) {
|
/* PACKETBUF_ATTR_MAC_SEQNO cannot be zero, due to a pecuilarity
|
in framer-802154.c. */
|
seqno++;
|
}
|
packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
|
|
/* Look for the neighbor entry */
|
n = neighbor_queue_from_addr(addr);
|
if(n == NULL) {
|
/* Allocate a new neighbor entry */
|
n = memb_alloc(&neighbor_memb);
|
if(n != NULL) {
|
/* Init neighbor entry */
|
rimeaddr_copy(&n->addr, addr);
|
n->transmissions = 0;
|
n->collisions = 0;
|
n->deferrals = 0;
|
/* Init packet list for this neighbor */
|
LIST_STRUCT_INIT(n, queued_packet_list);
|
/* Add neighbor to the list */
|
list_add(neighbor_list, n);
|
}
|
}
|
|
if(n != NULL) {
|
/* Add packet to the neighbor's queue */
|
q = memb_alloc(&packet_memb);
|
if(q != NULL) {
|
q->ptr = memb_alloc(&metadata_memb);
|
if(q->ptr != NULL) {
|
q->buf = queuebuf_new_from_packetbuf();
|
if(q->buf != NULL) {
|
struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
|
/* Neighbor and packet successfully allocated */
|
if(packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS) == 0) {
|
/* Use default configuration for max transmissions */
|
metadata->max_transmissions = CSMA_MAX_MAC_TRANSMISSIONS;
|
} else {
|
metadata->max_transmissions =
|
packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
|
}
|
metadata->sent = sent;
|
metadata->cptr = ptr;
|
|
if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) ==
|
PACKETBUF_ATTR_PACKET_TYPE_ACK) {
|
list_push(n->queued_packet_list, q);
|
} else {
|
list_add(n->queued_packet_list, q);
|
}
|
|
/* If q is the first packet in the neighbor's queue, send asap */
|
if(list_head(n->queued_packet_list) == q) {
|
ctimer_set(&n->transmit_timer, 0, transmit_packet_list, n);
|
}
|
return;
|
}
|
memb_free(&metadata_memb, q->ptr);
|
PRINTF("csma: could not allocate queuebuf, dropping packet\n");
|
}
|
memb_free(&packet_memb, q);
|
PRINTF("csma: could not allocate queuebuf, dropping packet\n");
|
}
|
/* The packet allocation failed. Remove and free neighbor entry if empty. */
|
if(list_length(n->queued_packet_list) == 0) {
|
list_remove(neighbor_list, n);
|
memb_free(&neighbor_memb, n);
|
}
|
PRINTF("csma: could not allocate packet, dropping packet\n");
|
} else {
|
PRINTF("csma: could not allocate neighbor, dropping packet\n");
|
}
|
mac_call_sent_callback(sent, ptr, MAC_TX_ERR, 1);
|
}
|
/*---------------------------------------------------------------------------*/
|
static void
|
input_packet(void)
|
{
|
NETSTACK_NETWORK.input();
|
}
|
/*---------------------------------------------------------------------------*/
|
static int
|
on(void)
|
{
|
return NETSTACK_RDC.on();
|
}
|
/*---------------------------------------------------------------------------*/
|
static int
|
off(int keep_radio_on)
|
{
|
return NETSTACK_RDC.off(keep_radio_on);
|
}
|
/*---------------------------------------------------------------------------*/
|
static unsigned short
|
channel_check_interval(void)
|
{
|
if(NETSTACK_RDC.channel_check_interval) {
|
return NETSTACK_RDC.channel_check_interval();
|
}
|
return 0;
|
}
|
/*---------------------------------------------------------------------------*/
|
static void
|
init(void)
|
{
|
memb_init(&packet_memb);
|
memb_init(&metadata_memb);
|
memb_init(&neighbor_memb);
|
}
|
/*---------------------------------------------------------------------------*/
|
const struct mac_driver csma_driver = {
|
"CSMA",
|
init,
|
send_packet,
|
input_packet,
|
on,
|
off,
|
channel_check_interval,
|
};
|
/*---------------------------------------------------------------------------*/
|
