candidate.c revision 8857
1148871Scperciva/*- 2148871Scperciva * Copyright (c) 1985, 1993 3148871Scperciva * The Regents of the University of California. All rights reserved. 4148871Scperciva * 5148871Scperciva * Redistribution and use in source and binary forms, with or without 6148871Scperciva * modification, are permitted provided that the following conditions 7148871Scperciva * are met: 8148871Scperciva * 1. Redistributions of source code must retain the above copyright 9148871Scperciva * notice, this list of conditions and the following disclaimer. 10148871Scperciva * 2. Redistributions in binary form must reproduce the above copyright 11148871Scperciva * notice, this list of conditions and the following disclaimer in the 12148871Scperciva * documentation and/or other materials provided with the distribution. 13148871Scperciva * 3. All advertising materials mentioning features or use of this software 14148871Scperciva * must display the following acknowledgement: 15148871Scperciva * This product includes software developed by the University of 16148871Scperciva * California, Berkeley and its contributors. 17148871Scperciva * 4. Neither the name of the University nor the names of its contributors 18148871Scperciva * may be used to endorse or promote products derived from this software 19148871Scperciva * without specific prior written permission. 20148871Scperciva * 21148871Scperciva * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22148871Scperciva * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23148871Scperciva * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24148871Scperciva * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25148871Scperciva * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26148871Scperciva * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27148871Scperciva * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28148871Scperciva * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29148871Scperciva * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30148871Scperciva * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31148871Scperciva * SUCH DAMAGE. 32148871Scperciva */ 33148871Scperciva 34148871Scperciva#ifndef lint 35148871Scpercivastatic char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93"; 36148871Scperciva#endif /* not lint */ 37149027Scperciva 38148871Scperciva#ifdef sgi 39148871Scperciva#ident "$Revision: 1.1.1.1 $" 40148871Scperciva#endif 41148871Scperciva 42148871Scperciva#include "globals.h" 43148871Scperciva 44148871Scperciva/* 45148871Scperciva * `election' candidates a host as master: it is called by a slave 46158523Scperciva * which runs with the -M option set when its election timeout expires. 47148871Scperciva * Note the conservative approach: if a new timed comes up, or another 48148871Scperciva * candidate sends an election request, the candidature is withdrawn. 49148871Scperciva */ 50148871Scpercivaint 51148871Scpercivaelection(net) 52148871Scperciva struct netinfo *net; 53148871Scperciva{ 54148871Scperciva struct tsp *resp, msg; 55148871Scperciva struct timeval then, wait; 56148871Scperciva struct tsp *answer; 57148871Scperciva struct hosttbl *htp; 58148871Scperciva char loop_lim = 0; 59148871Scperciva 60148871Scperciva/* This code can get totally confused if it gets slightly behind. For 61148871Scperciva * example, if readmsg() has some QUIT messages waiting from the last 62148871Scperciva * round, we would send an ELECTION message, get the stale QUIT, 63148871Scperciva * and give up. This results in network storms when several machines 64148871Scperciva * do it at once. 65148871Scperciva */ 66148871Scperciva wait.tv_sec = 0; 67148871Scperciva wait.tv_usec = 0; 68148871Scperciva while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) { 69148871Scperciva if (trace) 70148871Scperciva fprintf(fd, "election: discarded stale REFUSE\n"); 71148871Scperciva } 72148871Scperciva while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) { 73148871Scperciva if (trace) 74148871Scperciva fprintf(fd, "election: discarded stale QUIT\n"); 75148871Scperciva } 76149027Scperciva 77148871Scpercivaagain: 78148871Scperciva syslog(LOG_INFO, "This machine is a candidate time master"); 79148871Scperciva if (trace) 80148879Scperciva fprintf(fd, "This machine is a candidate time master\n"); 81148871Scperciva msg.tsp_type = TSP_ELECTION; 82148871Scperciva msg.tsp_vers = TSPVERSION; 83148871Scperciva (void)strcpy(msg.tsp_name, hostname); 84148871Scperciva bytenetorder(&msg); 85149824Scperciva if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, 86158523Scperciva (struct sockaddr*)&net->dest_addr, 87148871Scperciva sizeof(struct sockaddr)) < 0) { 88148871Scperciva trace_sendto_err(net->dest_addr.sin_addr); 89148871Scperciva return(SLAVE); 90148871Scperciva } 91148871Scperciva 92148871Scperciva (void)gettimeofday(&then, 0); 93148871Scperciva then.tv_sec += 3; 94148871Scperciva for (;;) { 95148871Scperciva (void)gettimeofday(&wait, 0); 96148871Scperciva timevalsub(&wait,&then,&wait); 97148871Scperciva resp = readmsg(TSP_ANY, ANYADDR, &wait, net); 98148871Scperciva if (!resp) 99148871Scperciva return(MASTER); 100148871Scperciva 101148871Scperciva switch (resp->tsp_type) { 102148871Scperciva 103148879Scperciva case TSP_ACCEPT: 104148871Scperciva (void)addmach(resp->tsp_name, &from,fromnet); 105148871Scperciva break; 106148871Scperciva 107148871Scperciva case TSP_MASTERUP: 108148871Scperciva case TSP_MASTERREQ: 109148871Scperciva /* 110148871Scperciva * If another timedaemon is coming up at the same 111148871Scperciva * time, give up, and let it be the master. 112148871Scperciva */ 113148871Scperciva if (++loop_lim < 5 114148871Scperciva && !good_host_name(resp->tsp_name)) { 115148871Scperciva (void)addmach(resp->tsp_name, &from,fromnet); 116148871Scperciva suppress(&from, resp->tsp_name, net); 117148871Scperciva goto again; 118148871Scperciva } 119148871Scperciva rmnetmachs(net); 120148871Scperciva return(SLAVE); 121148871Scperciva 122158523Scperciva case TSP_QUIT: 123158523Scperciva case TSP_REFUSE: 124158523Scperciva /* 125158523Scperciva * Collision: change value of election timer 126158523Scperciva * using exponential backoff. 127148871Scperciva * 128148871Scperciva * Fooey. 129148871Scperciva * An exponential backoff on a delay starting at 130148871Scperciva * 6 to 15 minutes for a process that takes 131148871Scperciva * milliseconds is silly. It is particularly 132148871Scperciva * strange that the original code would increase 133148871Scperciva * the backoff without bound. 134148871Scperciva */ 135148871Scperciva rmnetmachs(net); 136148871Scperciva return(SLAVE); 137148871Scperciva 138148871Scperciva case TSP_ELECTION: 139148871Scperciva /* no master for another round */ 140148871Scperciva htp = addmach(resp->tsp_name,&from,fromnet); 141148871Scperciva msg.tsp_type = TSP_REFUSE; 142148871Scperciva (void)strcpy(msg.tsp_name, hostname); 143148871Scperciva answer = acksend(&msg, &htp->addr, htp->name, 144149027Scperciva TSP_ACK, 0, htp->noanswer); 145148871Scperciva if (!answer) { 146148871Scperciva syslog(LOG_ERR, "error in election from %s", 147148871Scperciva htp->name); 148149027Scperciva } 149149027Scperciva break; 150149027Scperciva 151148871Scperciva case TSP_SLAVEUP: 152148871Scperciva (void)addmach(resp->tsp_name, &from,fromnet); 153148871Scperciva break; 154148871Scperciva 155148871Scperciva case TSP_SETDATE: 156148871Scperciva case TSP_SETDATEREQ: 157149027Scperciva break; 158148871Scperciva 159148871Scperciva default: 160148871Scperciva if (trace) { 161148871Scperciva fprintf(fd, "candidate: "); 162148871Scperciva print(resp, &from); 163148871Scperciva } 164148871Scperciva break; 165148871Scperciva } 166148871Scperciva } 167148871Scperciva} 168148871Scperciva