RIOT/sys/net/sixlowpan/rpl/etx_beaconing.c

/*
 * etx_beaconing.c
 *
 *  Created on: Feb 26, 2013
 *      Author: stephan
 */
#include "etx_beaconing.h"

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#include <hwtimer.h>
#include <vtimer.h>
#include <thread.h>
#include <transceiver.h>

#include "sys/net/sixlowpan/sixlowmac.h"
#include "sys/net/sixlowpan/ieee802154_frame.h"
#include "rpl_structs.h"
#include "rpl_dodag.h"

//For debugging purposes
#include <debug.h>
//#define ENABLE_DEBUG

char etx_radio_buf[ETX_RADIO_STACKSIZE] = { 0 };
char etx_update_buf[ETX_UPDT_STACKSIZE] = { 0 };

int etx_beacon_pid = 0;
int etx_radio_pid = 0;
int etx_update_pid = 0;

//Buffer
uint8_t etx_send_buf[ETX_BUF_SIZE] = { 0 };
uint8_t etx_rec_buf[ETX_BUF_SIZE] = { 0 };
char etx_beacon_buf[ETX_BEACON_STACKSIZE] = { 0 };

//Message queue for radio
msg_t msg_que[ETX_RCV_QUEUE_SIZE] = { 0 };

/*
 * The counter for the current 'round'. An ETX beacon is sent every ETX_INTERVAL
 * u-seconds and a node computes the ETX value by comparing the the received
 * probes vs the expected probes from a neighbor every ETX_ROUND intervals.
 */
static uint8_t rounds = 0;

/*
 * This could (and should) be done differently, once the RPL implementation
 * deals with candidate neighbors in another way than just defining that every
 * possible neighbor we hear from is a parent.
 * Right now, we need to keep track of the ETX values of other nodes without
 * needing them to be in our parent array, so we have another array here in
 * which we put all necessary info for up to RPL_MAX_CANDIDATE_NEIGHBORS
 * candidates.
 */
//Candidate array for candidate<==>parent matching
//Throws a warning, but this is the correct way to initialize!
static rpl_candidate_neighbor_t candidates[RPL_MAX_CANDIDATE_NEIGHBORS] = { 0 };

//Transceiver command for sending ETX probes
transceiver_command_t tcmd;

//Message to send probes with
msg_t mesg;

//RPL-address
static ipv6_addr_t * own_address;

static etx_probe_t * get_etx_send_buf(void) {
    return ((etx_probe_t *) &(etx_send_buf[0]));
}
static etx_probe_t * get_etx_rec_buf(void) {
    return ((etx_probe_t *) &(etx_rec_buf[0]));
}

void show_candidates(void) {
    rpl_candidate_neighbor_t * candidate;
    rpl_candidate_neighbor_t *end;

    for (candidate = &candidates[0], end = candidates
            + RPL_MAX_CANDIDATE_NEIGHBORS; candidate < end;
            candidate++) {
        DEBUG("Candidates Addr:%d\n"
                "\t cur_etx:%f\n"
                "\t packets_rx:%d\n"
                "\t used:%d\n", candidate->addr.uint8[ETX_IPV6_LAST_BYTE],
                candidate->cur_etx, candidate->packets_rx,
                candidate->used);
    }
}

void etx_init_beaconing(ipv6_addr_t * address) {
    own_address = address;
    //set code
    puts("ETX BEACON INIT");
    etx_send_buf[0] = ETX_BEACON;

    thread_print_all();
    etx_beacon_pid = thread_create(etx_beacon_buf, ETX_BEACON_STACKSIZE,
            PRIORITY_MAIN - 1, CREATE_STACKTEST,
            etx_beacon, "etx_beacon");

    etx_radio_pid = thread_create(etx_radio_buf, ETX_RADIO_STACKSIZE,
            PRIORITY_MAIN - 1, CREATE_STACKTEST,
            etx_radio, "etx_radio");

    /*
     * Maybe this should not be in a seperate thread resource-wise, but the
     * motive was to delay beacon-sending as little as possible, as this would
     * derail beaconing from the intended ETX_INTERVAL.
     */

    etx_update_pid = thread_create(etx_update_buf, ETX_UPDT_STACKSIZE,
            PRIORITY_MAIN - 1, CREATE_STACKTEST,
            etx_update, "etx_update");

    //register at transceiver
    transceiver_register(TRANSCEIVER_CC1100, etx_radio_pid);
    puts("...[DONE]");
}

void etx_beacon(void) {
    /*
     * Sends a message every ETX_INTERVAL +/- a jitter-value (default is 10%) .
     * A correcting variable is needed to stay at a base interval of
     * ETX_INTERVAL between the wakeups. It takes the old jittervalue in account
     * and modifies the time to wait accordingly.
     */
    etx_probe_t *etx_p = get_etx_send_buf();

    /*
     * The jittercorrection and jitter variables keep usecond values divided
     * through 1000 to fit into uint8 variables.
     *
     * That is why they are multiplied by 1000 when used for hwtimer_wait.
     */
    uint8_t jittercorrection = ETX_DEF_JIT_CORRECT;
    uint8_t jitter = (uint8_t) (rand() % ETX_JITTER_MOD);

    uint8_t p_length = 0;

    ieee_802154_long_t empty_addr = { 0 };

    while (true) {

        if (rounds == ETX_ROUNDS) {
            //calculate the ETX values and update the parents
            thread_wakeup(etx_update_pid);
            rounds = 1;
        } else {
            rounds++;
        }

        //Build etx packet
        p_length = 0;
        for (uint8_t i = 0; i < RPL_MAX_CANDIDATE_NEIGHBORS; i++) {
            if (candidates[i].used != 0) {
                etx_p->data[i * ETX_TUPLE_SIZE] =
                        candidates[i].addr.uint8[ETX_IPV6_LAST_BYTE];
                etx_p->data[i * ETX_TUPLE_SIZE + ETX_PKT_REC_OFFSET] =
                        candidates[i].packets_tx;
                p_length = p_length + ETX_PKT_HDR_LEN;
            }
        }
        etx_p->length = p_length;

        send_ieee802154_frame(&empty_addr, &etx_send_buf[0],
                get_etx_send_buf()->length + ETX_PKT_HDR_LEN, 1);
        puts("sent beacon!");
        //vtimer_usleep(((ETX_INTERVAL - ETX_MAX_JITTER)*MS) + jittercorrection*MS + jitter*MS);
        /// TODO once vtimer works as intended, replace the hwtimer here with
        /// the vtimer. Right now vtimer bugs, so we have hwtimer here.
        hwtimer_wait(
                HWTIMER_TICKS(((ETX_INTERVAL - ETX_MAX_JITTER)*MS) + jittercorrection*MS + jitter*MS));

        jittercorrection = (ETX_MAX_JITTER) - jitter;

        //the jitter is a value between 0 and ETX_MAX_JITTER
        jitter = (uint8_t) (rand() % ETX_JITTER_MOD);
    }
}

rpl_candidate_neighbor_t * etx_find_candidate(ipv6_addr_t * address) {
    /*
     * find the candidate with address address and returns it, or returns NULL
     * if no candidate having this address was found.
     */
    for (uint8_t i = 0; i < RPL_MAX_CANDIDATE_NEIGHBORS; i++) {
        if (candidates[i].used
                && (rpl_equal_id(&candidates[i].addr, address))) {
            return &candidates[i];
        }
    }
    return NULL ;
}

double etx_get_metric(ipv6_addr_t * address) {
    rpl_candidate_neighbor_t * candidate = etx_find_candidate(address);
    if (candidate != NULL ) {
        return candidate->packets_rx / (double) ETX_ROUNDS;
    }
    return 0;
}

rpl_candidate_neighbor_t * etx_add_candidate(ipv6_addr_t * address) {
    puts("add candidate");
    /*
     * Pre-Condition:   etx_add_candidate should only be called when the
     *                  candidate is not yet in the list.
     *                  Otherwise the candidate will be added a second time,
     *                  leading to unknown behavior.
     *
     *      Check if there is still enough space to add this candidate
     *
     *      a)
     *          Space is available:
     *              Add candidate
     *
     *      b)
     *          Space is not available:
     *              ignore new candidate
     *              This shouldn't really happen though, since we have enough
     *              place in the array.
     *
     * Returns the pointer to the candidate if it was added, or a NULL-pointer
     * otherwise.
     */
    rpl_candidate_neighbor_t * candidate;
    rpl_candidate_neighbor_t * end;

    for (candidate = &candidates[0], end = candidates
            + RPL_MAX_CANDIDATE_NEIGHBORS; candidate < end;
            candidate++) {
        if (candidate->used) {
            //skip
            continue;
        } else {
            //We still have a free place add the new candidate
            candidate->addr = *address;
            candidate->cur_etx = 0;
            candidate->packets_tx = 0;
            candidate->packets_rx = 0;
            candidate->used = 1;
            return candidate;
        }
    }
    return NULL ;
}

void etx_handle_beacon(ipv6_addr_t * candidate_address) {
    /*
     * Handle the ETX probe that has been received and update all infos.
     * If the candidate address is unknown, try to add it to my struct.
     */

    etx_probe_t * probe = get_etx_rec_buf();

    DEBUG("ETX beacon package received with following values:\n"
            "\tPackage Option:%x\n"
            "\t   Data Length:%u\n"
            "\tSource Address:%d\n\n", probe->code, probe->length,
            candidate_address->uint8[ETX_IPV6_LAST_BYTE]);

    rpl_candidate_neighbor_t* candidate = etx_find_candidate(candidate_address);
    if (candidate == NULL ) {
        //Candidate was not found in my list, I should add it
        candidate = etx_add_candidate(candidate_address);
        if (candidate == NULL ) {
            puts("[ERROR] Candidate could not get added");
            puts("Increase the constant RPL_MAX_CANDIDATE_NEIGHBORS");
            return;
        }
    }

    //I have received 1 more packet from this candidate
    candidate->packets_tx = candidate->packets_tx + 1;

    // If i find my address in this probe, update the packet_rx value for
    // this candidate.
    for (uint8_t i = 0; i < probe->length / ETX_TUPLE_SIZE; i++) {
        DEBUG("\tIPv6 short  Addr:%u\n"
                "\tPackets f. Addr:%u\n\n", probe->data[i * ETX_TUPLE_SIZE],
                probe->data[i * ETX_TUPLE_SIZE + ETX_PKT_REC_OFFSET]);

        if (probe->data[i * ETX_TUPLE_SIZE]
                == own_address->uint8[ETX_IPV6_LAST_BYTE]) {

            candidate->packets_rx = probe->data[i * ETX_TUPLE_SIZE
                    + ETX_PKT_REC_OFFSET];
        }
    }
}

void etx_radio(void) {
    msg_t m;
    radio_packet_t *p;

    ieee802154_frame_t frame;

    msg_init_queue(msg_que, ETX_RCV_QUEUE_SIZE);

    ipv6_addr_t ll_address;
    ipv6_addr_t candidate_addr;

    ipv6_set_ll_prefix(&ll_address);
    ipv6_get_saddr(&candidate_addr, &ll_address);

    while (1) {
        msg_receive(&m);
        if (m.type == PKT_PENDING) {
            p = (radio_packet_t*) m.content.ptr;

            read_802154_frame(p->data, &frame, p->length);

            if (frame.payload[0] == ETX_BEACON) {
                //copy to receive buffer
                memcpy(etx_rec_buf, &frame.payload[0], frame.payload_len);

                //create IPv6 address from radio packet
                //we can do the cast here since rpl nodes can only have addr
                //up to 8 bits
                candidate_addr.uint8[ETX_IPV6_LAST_BYTE] = (uint8_t) p->src;
                //handle the beacon
                etx_handle_beacon(&candidate_addr);
            }

            p->processing--;
        }
        else if (m.type == ENOBUFFER) {
            puts("Transceiver buffer full");
        }
        else {
            //packet is not for me, whatever
        }
    }
}

void etx_update(void) {
    /*
     * Update the current ETX values, then
     * reset the received packet count for the candidates.
     *
     * This thread should never take very long, as it has to be done in less
     * than (ETX_INTERVAL - maximum jitter), otherwise the ETX calculation might
     * be faulty. TODO delete this once mutexes are in place
     *
     */
    rpl_candidate_neighbor_t * candidate;
    rpl_candidate_neighbor_t * end;

    while (true) {
        //good night
        thread_sleep();
        //Wait a tiny bit to allow for the last packet to be processed
        hwtimer_wait(HWTIMER_TICKS(200));

        for (candidate = &candidates[0], end = candidates
                + RPL_MAX_CANDIDATE_NEIGHBORS; candidate < end;
                candidate++) {

            if (candidate->used != 0) {
                //update its ETX-metric and packet count TODO mutex this
                //TODO probably better to change floating point-math to integer
                //based math
                candidate->cur_etx =
                        candidate->packets_rx / (double) ETX_ROUNDS;
                candidate->packets_rx = 0;
                DEBUG(
                        "Updated ETX Metric to %f for candidate used was on %d",
                        candidate->cur_etx, candidate->used);
            }
        }
    }
}