contiki/examples/trickle-library/trickle-library.c
Peter A. Bigot eecb2c6183 examples/trickle-library: correct probability expression
Documented intent is to update with probability 1/NEW_TOKEN_PROB where
NEW_TOKEN_PROB is 0x80.  The current implementation updates with probability
1/2.  Update NEW_TOKEN_PROB and the expression to keep existing behavior
while correcting the calculation.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
2013-06-17 13:03:37 -05:00

195 lines
7.2 KiB
C

/*
* Copyright (c) 2012, George Oikonomou - <oikonomou@users.sourceforge.net>
* 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 copyright holder 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
/* Example trickle-based protocol demonstrating the functionality of the
* trickle (trickle_timer) library (RFC 6206) */
#include "contiki.h"
#include "contiki-lib.h"
#include "contiki-net.h"
#include "lib/trickle-timer.h"
#include "dev/leds.h"
#include "lib/random.h"
#include <string.h>
#define DEBUG DEBUG_PRINT
#include "net/uip-debug.h"
/* Trickle variables and constants */
static struct trickle_timer tt;
#define IMIN 16 /* ticks */
#define IMAX 10 /* doublings */
#define REDUNDANCY_CONST 2
/* Networking */
#define TRICKLE_PROTO_PORT 30001
static struct uip_udp_conn *trickle_conn;
static uip_ipaddr_t ipaddr; /* destination: link-local all-nodes multicast */
/*
* For this 'protocol', nodes exchange a token (1 byte) at a frequency
* governed by trickle. A node detects an inconsistency when it receives a
* token different than the one it knows.
* In this case, either:
* - 'they' have a 'newer' token and we also update our own value, or
* - 'we' have a 'newer' token, in which case we trigger an inconsistency
* without updating our value.
* In this context, 'newer' is defined in serial number arithmetic terms.
*
* Every NEW_TOKEN_INTERVAL clock ticks each node will generate a new token
* with probability 1/NEW_TOKEN_PROB. This is controlled by etimer et.
*/
#define NEW_TOKEN_INTERVAL 10 * CLOCK_SECOND
#define NEW_TOKEN_PROB 2
static uint8_t token;
static struct etimer et; /* Used to periodically generate inconsistencies */
/*---------------------------------------------------------------------------*/
PROCESS(trickle_protocol_process, "Trickle Protocol process");
AUTOSTART_PROCESSES(&trickle_protocol_process);
/*---------------------------------------------------------------------------*/
static void
tcpip_handler(void)
{
leds_on(LEDS_GREEN);
if(uip_newdata()) {
PRINTF("At %lu (I=%lu, c=%u): ",
(unsigned long)clock_time(), (unsigned long)tt.i_cur, tt.c);
PRINTF("Our token=0x%02x, theirs=0x%02x\n", token,
((uint8_t *)uip_appdata)[0]);
if(token == ((uint8_t *)uip_appdata)[0]) {
PRINTF("Consistent RX\n");
trickle_timer_consistency(&tt);
} else {
if((signed char)(token - ((uint8_t *)uip_appdata)[0]) < 0) {
PRINTF("Theirs is newer. Update\n");
token = ((uint8_t *)uip_appdata)[0];
} else {
PRINTF("They are behind\n");
}
trickle_timer_inconsistency(&tt);
/*
* Here tt.ct.etimer.timer.{start + interval} points to time t in the
* current interval. However, between t and I it points to the interval's
* end so if you're going to use this, do so with caution.
*/
PRINTF("At %lu: Trickle inconsistency. Scheduled TX for %lu\n",
(unsigned long)clock_time(),
(unsigned long)(tt.ct.etimer.timer.start +
tt.ct.etimer.timer.interval));
}
}
leds_off(LEDS_GREEN);
return;
}
/*---------------------------------------------------------------------------*/
static void
trickle_tx(void *ptr, uint8_t suppress)
{
/* *ptr is a pointer to the trickle_timer that triggered this callback. In
* his example we know that ptr points to tt. However, we pretend that we did
* not know (which would be the case if we e.g. had multiple trickle timers)
* and cast it to a local struct trickle_timer* */
struct trickle_timer *loc_tt = (struct trickle_timer *)ptr;
if(suppress == TRICKLE_TIMER_TX_SUPPRESS) {
return;
}
leds_on(LEDS_RED);
PRINTF("At %lu (I=%lu, c=%u): ",
(unsigned long)clock_time(), (unsigned long)loc_tt->i_cur,
loc_tt->c);
PRINTF("Trickle TX token 0x%02x\n", token);
/* Instead of changing ->ripaddr around by ourselves, we could have used
* uip_udp_packet_sendto which would have done it for us. However it puts an
* extra ~20 bytes on stack and the cc2x3x micros hate it, so we stick with
* send() */
/* Destination IP: link-local all-nodes multicast */
uip_ipaddr_copy(&trickle_conn->ripaddr, &ipaddr);
uip_udp_packet_send(trickle_conn, &token, sizeof(token));
/* Restore to 'accept incoming from any IP' */
uip_create_unspecified(&trickle_conn->ripaddr);
leds_off(LEDS_RED);
}
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(trickle_protocol_process, ev, data)
{
PROCESS_BEGIN();
PRINTF("Trickle protocol started\n");
uip_create_linklocal_allnodes_mcast(&ipaddr); /* Store for later */
trickle_conn = udp_new(NULL, UIP_HTONS(TRICKLE_PROTO_PORT), NULL);
udp_bind(trickle_conn, UIP_HTONS(TRICKLE_PROTO_PORT));
PRINTF("Connection: local/remote port %u/%u\n",
UIP_HTONS(trickle_conn->lport), UIP_HTONS(trickle_conn->rport));
token = 0;
trickle_timer_config(&tt, IMIN, IMAX, REDUNDANCY_CONST);
trickle_timer_set(&tt, trickle_tx, &tt);
/*
* At this point trickle is started and is running the first interval. All
* nodes 'agree' that token == 0. This will change when one of them randomly
* decides to generate a new one
*/
etimer_set(&et, NEW_TOKEN_INTERVAL);
while(1) {
PROCESS_YIELD();
if(ev == tcpip_event) {
tcpip_handler();
} else if(etimer_expired(&et)) {
/* Periodically (and randomly) generate a new token. This will trigger
* a trickle inconsistency */
if((random_rand() % NEW_TOKEN_PROB) == 0) {
token++;
PRINTF("At %lu: Generating a new token 0x%02x\n",
(unsigned long)clock_time(), token);
trickle_timer_reset_event(&tt);
}
etimer_set(&et, NEW_TOKEN_INTERVAL);
}
}
PROCESS_END();
}
/*---------------------------------------------------------------------------*/