.ref-BSD-4_3_Net_2/usr/src/usr.sbin/timed/timed/candidate.c

/*
 * Copyright (c) 1983 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 */

#ifndef lint
static char sccsid[] = "@(#)candidate.c 2.7 (Berkeley) 3/2/91";
#endif /* not lint */

#include "globals.h"
#include <protocols/timed.h>

#define ELECTIONWAIT    3       /* seconds */

/*
 * `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 * candidate sends an election request, the candidature is withdrawn.
 */

election(net)
struct netinfo *net;
{
        int ret;
        struct tsp *resp, msg, *readmsg();
        struct timeval wait;
        struct tsp *answer, *acksend();
        long casual();
        struct sockaddr_in server;

        syslog(LOG_INFO, "THIS MACHINE IS A CANDIDATE");
        if (trace) {
                fprintf(fd, "THIS MACHINE IS A CANDIDATE\n");
        }

        ret = MASTER;
        slvcount = 1;

        msg.tsp_type = TSP_ELECTION;
        msg.tsp_vers = TSPVERSION;
        (void)strcpy(msg.tsp_name, hostname);
        bytenetorder(&msg);
        if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
                (struct sockaddr *)&net->dest_addr,
                sizeof(struct sockaddr_in)) < 0) {
                syslog(LOG_ERR, "sendto: %m");
                exit(1);
        }

        do {
                wait.tv_sec = ELECTIONWAIT;
                wait.tv_usec = 0;
                resp = readmsg(TSP_ANY, (char *)ANYADDR, &wait, net);
                if (resp != NULL) {
                        switch (resp->tsp_type) {

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

                        case TSP_MASTERUP:
                        case TSP_MASTERREQ:
                                /*
                                 * If a timedaemon is coming up at the same time,
                                 * give up the candidature: it will be the master.
                                 */
                                ret = SLAVE;
                                break;

                        case TSP_QUIT:
                        case TSP_REFUSE:
                                /*
                                 * Collision: change value of election timer
                                 * using exponential backoff.
                                 * The value of timer will be recomputed (in slave.c)
                                 * using the original interval when election will
                                 * be successfully completed.
                                 */
                                backoff *= 2;
                                delay2 = casual((long)MINTOUT,
                                                        (long)(MAXTOUT * backoff));
                                ret = SLAVE;
                                break;

                        case TSP_ELECTION:
                                /* no master for another round */
                                msg.tsp_type = TSP_REFUSE;
                                (void)strcpy(msg.tsp_name, hostname);
                                server = from;
                                answer = acksend(&msg, &server, resp->tsp_name,
                                    TSP_ACK, (struct netinfo *)NULL);
                                if (answer == NULL) {
                                        syslog(LOG_ERR, "error in election");
                                } else {
                                        (void) addmach(resp->tsp_name, &from);
                                }
                                break;

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

                        case TSP_SETDATE:
                        case TSP_SETDATEREQ:
                                break;

                        default:
                                if (trace) {
                                        fprintf(fd, "candidate: ");
                                        print(resp, &from);
                                }
                                break;
                        }
                } else {
                        break;
                }
        } while (ret == MASTER);
        return(ret);
}