/*      $NetBSD: timer.c,v 1.20 2021/03/23 18:16:53 christos Exp $      */
/*      $KAME: timer.c,v 1.11 2005/04/14 06:22:35 suz Exp $     */

/*
 * Copyright (C) 1998 WIDE Project.
 * 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 project 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 PROJECT 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 PROJECT 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.
 */

#include <sys/queue.h>
#include <sys/time.h>

#include <assert.h>
#include <limits.h>
#include <unistd.h>
#include <syslog.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <search.h>
#include "timer.h"
#include "logit.h"
#include "prog_ops.h"

struct rtadvd_timer_head_t ra_timer = TAILQ_HEAD_INITIALIZER(ra_timer);
static struct timespec tm_limit = { LONG_MAX, 1000000000L - 1 };
static struct timespec tm_max;

void
rtadvd_timer_init(void)
{

        TAILQ_INIT(&ra_timer);
        tm_max = tm_limit;
}

struct rtadvd_timer *
rtadvd_add_timer(struct rtadvd_timer *(*timeout) (void *),
    void (*update) (void *, struct timespec *),
    void *timeodata, void *updatedata)
{
        struct rtadvd_timer *newtimer;

        assert(timeout != NULL);

        if ((newtimer = malloc(sizeof(*newtimer))) == NULL) {
                logit(LOG_ERR, "%s: malloc: %m", __func__);
                exit(EXIT_FAILURE);
        }

        memset(newtimer, 0, sizeof(*newtimer));

        newtimer->expire = timeout;
        newtimer->update = update;
        newtimer->expire_data = timeodata;
        newtimer->update_data = updatedata;
        newtimer->tm = tm_max;

        /* link into chain */
        TAILQ_INSERT_TAIL(&ra_timer, newtimer, next);

        return(newtimer);
}

void
rtadvd_remove_timer(struct rtadvd_timer **timer)
{

        if (*timer) {
                TAILQ_REMOVE(&ra_timer, *timer, next);
                free(*timer);
                *timer = NULL;
        }
}

void
rtadvd_set_timer(struct timespec *tm, struct rtadvd_timer *timer)
{
        struct timespec now;

        /* reset the timer */
        prog_clock_gettime(CLOCK_MONOTONIC, &now);
        timespecadd(&now, tm, &timer->tm);

        /* update the next expiration time */
        if (timespeccmp(&timer->tm, &tm_max, <))
                tm_max = timer->tm;

        /* enable the timer */
        timer->enabled = true;
}

/*
 * Check expiration for each timer. If a timer expires,
 * call the expire function for the timer and update the timer.
 * Return the next interval for select() call.
 */
struct timespec *
rtadvd_check_timer(void)
{
        static struct timespec returnval;
        struct timespec now;
        struct rtadvd_timer *tm, *tmn;

        prog_clock_gettime(CLOCK_MONOTONIC, &now);
        tm_max = tm_limit;

        TAILQ_FOREACH_SAFE(tm, &ra_timer, next, tmn) {
                if (!tm->enabled)
                        continue;
                if (timespeccmp(&tm->tm, &now, <=)) {
                        if ((*tm->expire)(tm->expire_data) == NULL)
                                continue; /* the timer was removed */
                        if (tm->update)
                                (*tm->update)(tm->update_data, &tm->tm);
                        timespecadd(&tm->tm, &now, &tm->tm);
                }
                if (timespeccmp(&tm->tm, &tm_max, <))
                        tm_max = tm->tm;
        }

        if (timespeccmp(&tm_max, &tm_limit, ==))
                return(NULL);
        if (timespeccmp(&tm_max, &now, <)) {
                /* this may occur when the interval is too small */
                timespecclear(&returnval);
        } else
                timespecsub(&tm_max, &now, &returnval);
        return(&returnval);
}

struct timespec *
rtadvd_timer_rest(struct rtadvd_timer *timer)
{
        static struct timespec returnval;
        struct timespec now;

        prog_clock_gettime(CLOCK_MONOTONIC, &now);
        if (timespeccmp(&timer->tm, &now, <=)) {
                if (timer->enabled)
                        logit(LOG_DEBUG,
                               "%s: a timer must be expired, but not yet",
                               __func__);
                returnval.tv_sec = 0;
                returnval.tv_nsec = 0;
        }
        else
                timespecsub(&timer->tm, &now, &returnval);

        return(&returnval);
}