/*      $NetBSD: correct.c,v 1.14 2007/05/17 00:36:12 christos Exp $    */

/*-
 * Copyright (c) 1985, 1993 The Regents of the University of California.
 * 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 University 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 REGENTS 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 REGENTS 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/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)correct.c   8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: correct.c,v 1.14 2007/05/17 00:36:12 christos Exp $");
#endif
#endif /* not lint */

#include "globals.h"
#include <math.h>
#include <sys/types.h>
#include <sys/times.h>

static void adjclock(struct timeval*);

/*
 * sends to the slaves the corrections for their clocks after fixing our
 * own
 */
void
correct(long avdelta)
{
        struct hosttbl *htp;
        long corr;
        struct timeval adjlocal, tmptv;
        struct tsp to;
        struct tsp *answer;

        mstotvround(&adjlocal, avdelta);

        for (htp = self.l_fwd; htp != &self; htp = htp->l_fwd) {
                if (htp->delta != HOSTDOWN)  {
                        corr = avdelta - htp->delta;
/* If the other machine is off in the weeds, set its time directly.
 *      If a slave gets the wrong day, the original code would simply
 *      fix the minutes.  If you fix a network partition, you can get
 *      into such situations.
 */
                        if (htp->need_set
                            || corr >= MAXADJ*1000
                            || corr <= -MAXADJ*1000) {
                                htp->need_set = 0;
                                (void)gettimeofday(&tmptv,0);
                                timeradd(&tmptv, &adjlocal, &tmptv);
                                to.tsp_time.tv_sec = tmptv.tv_sec;
                                to.tsp_time.tv_usec = tmptv.tv_usec;
                                to.tsp_type = TSP_SETTIME;
                        } else {
                                tmptv.tv_sec = to.tsp_time.tv_sec ;
                                tmptv.tv_usec = to.tsp_time.tv_usec ;
                                mstotvround(&tmptv, corr);
                                to.tsp_time.tv_sec = tmptv.tv_sec;
                                to.tsp_time.tv_usec = tmptv.tv_usec;
                                to.tsp_type = TSP_ADJTIME;
                        }
                        set_tsp_name(&to, hostname);
                        answer = acksend(&to, &htp->addr, htp->name,
                                         TSP_ACK, 0, 0);
                        if (!answer) {
                                htp->delta = HOSTDOWN;
                                syslog(LOG_WARNING,
                                       "no reply to time correction from %s",
                                       htp->name);
                                if (++htp->noanswer >= LOSTHOST) {
                                        if (trace) {
                                                fprintf(fd,
                                             "purging %s for not answering\n",
                                                        htp->name);
                                                (void)fflush(fd);
                                        }
                                        htp = remmach(htp);
                                }
                        }
                }
        }

        /*
         * adjust our own clock now that we are not sending it out
         */
        adjclock(&adjlocal);
}


static void
adjclock(struct timeval *corr)
{
        static int passes = 0;
        static int smoother = 0;
        long delta;                     /* adjustment in usec */
        long ndelta;
        struct timeval now;
        struct timeval adj;

        if (!timerisset(corr))
                return;

        adj = *corr;
        if (adj.tv_sec < MAXADJ && adj.tv_sec > - MAXADJ) {
                delta = adj.tv_sec*1000000 + adj.tv_usec;
                /* If the correction is less than the minimum round
                 *      trip time for an ICMP packet, and thus
                 *      less than the likely error in the measurement,
                 *      do not do the entire correction.  Do half
                 *      or a quarter of it.
                 */

                if (delta > -MIN_ROUND*1000
                    && delta < MIN_ROUND*1000) {
                        if (smoother <= 4)
                                smoother++;
                        ndelta = (unsigned long)delta >> smoother;
                        if (delta < 0) {
                                long mask = (long)~0 & 
                                    ~((1 << ((sizeof(long) * NBBY) - smoother))
                                    - 1);
                                ndelta |= mask;
                        }
                        if (trace)
                                fprintf(fd,
                                        "trimming delta %ld usec to %ld\n",
                                        delta, ndelta);
                        adj.tv_usec = ndelta;
                        adj.tv_sec = 0;
                } else if (smoother > 0) {
                        smoother--;
                }
                if (0 > adjtime(corr, 0)) {
                        syslog(LOG_ERR, "adjtime: %m");
                }
                if (passes > 1
                    && (delta < -BIG_ADJ || delta > BIG_ADJ)) {
                        smoother = 0;
                        passes = 0;
                        syslog(LOG_WARNING,
                               "large time adjustment of %+.3f sec",
                               delta/1000000.0);
                }
        } else {
                syslog(LOG_WARNING,
                       "clock correction %ld sec too large to adjust",
                       (long)adj.tv_sec);
                (void) gettimeofday(&now, 0);
                timeradd(&now, corr, &now);
                if (settimeofday(&now, 0) < 0)
                        syslog(LOG_ERR, "settimeofday: %m");
        }
}


/* adjust the time in a message by the time it
 *      spent in the queue
 */
void
adj_msg_time(struct tsp *msg, struct timeval *now)
{
        struct timeval diff;

        timersub(now, &from_when, &diff);
        timeradd(&msg->tsp_time, &diff, &msg->tsp_time);
}