/*-
 * 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[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93";
#else
__RCSID("$NetBSD: candidate.c,v 1.12 2007/01/26 16:12:41 christos Exp $");
#endif
#endif /* not lint */

#include "globals.h"

/*
 * `election' candidates a host as master: it is called by a slave
 * which runs with the -M option set when its election timeout expires.
 * Note the conservative approach: if a new timed comes up, or another
 * candidate sends an election request, the candidature is withdrawn.
 */
int
election(struct netinfo *net)
{
        struct tsp *resp, msg;
        struct timeval then, wait;
        struct tsp *answer;
        struct hosttbl *htp;
        char loop_lim = 0;

/* This code can get totally confused if it gets slightly behind.  For
 *      example, if readmsg() has some QUIT messages waiting from the last
 *      round, we would send an ELECTION message, get the stale QUIT,
 *      and give up.  This results in network storms when several machines
 *      do it at once.
 */
        wait.tv_sec = 0;
        wait.tv_usec = 0;
        while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
                if (trace)
                        fprintf(fd, "election: discarded stale REFUSE\n");
        }
        while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
                if (trace)
                        fprintf(fd, "election: discarded stale QUIT\n");
        }

again:
        syslog(LOG_INFO, "This machine is a candidate time master");
        if (trace)
                fprintf(fd, "This machine is a candidate time master\n");
        msg.tsp_type = TSP_ELECTION;
        msg.tsp_vers = TSPVERSION;
        set_tsp_name(&msg, hostname);
        bytenetorder(&msg);
        if (sendtsp(sock, &msg, &net->dest_addr) == -1)
                return(SLAVE);

        (void)gettimeofday(&then, 0);
        then.tv_sec += 3;
        for (;;) {
                (void)gettimeofday(&wait, 0);
                timersub(&then, &wait, &wait);
                resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
                if (!resp)
                        return(MASTER);

                switch (resp->tsp_type) {

                case TSP_ACCEPT:
                        (void)addmach(resp->tsp_name, &from,fromnet);
                        break;

                case TSP_MASTERUP:
                case TSP_MASTERREQ:
                        /*
                         * If another timedaemon is coming up at the same
                         * time, give up, and let it be the master.
                         */
                        if (++loop_lim < 5
                            && !good_host_name(resp->tsp_name)) {
                                (void)addmach(resp->tsp_name, &from,fromnet);
                                suppress(&from, resp->tsp_name, net);
                                goto again;
                        }
                        rmnetmachs(net);
                        return(SLAVE);

                case TSP_QUIT:
                case TSP_REFUSE:
                        /*
                         * Collision: change value of election timer
                         * using exponential backoff. 
                         *
                         *  Fooey.
                         * An exponential backoff on a delay starting at
                         * 6 to 15 minutes for a process that takes
                         * milliseconds is silly.  It is particularly
                         * strange that the original code would increase
                         * the backoff without bound.
                         */
                        rmnetmachs(net);
                        return(SLAVE);

                case TSP_ELECTION:
                        /* no master for another round */
                        htp = addmach(resp->tsp_name,&from,fromnet);
                        msg.tsp_type = TSP_REFUSE;
                        set_tsp_name(&msg, hostname);
                        answer = acksend(&msg, &htp->addr, htp->name,
                                         TSP_ACK, 0, htp->noanswer);
                        if (!answer) {
                                syslog(LOG_ERR, "error in election from %s",
                                       htp->name);
                        }
                        break;

                case TSP_SLAVEUP:
                        (void)addmach(resp->tsp_name, &from,fromnet);
                        break;

                case TSP_SETDATE:
                case TSP_SETDATEREQ:
                        break;

                default:
                        if (trace) {
                                fprintf(fd, "candidate: ");
                                print(resp, &from);
                        }
                        break;
                }
        }
}