1/*- 2 * Copyright (c) 1985, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#ifndef lint 31#if 0 32static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93"; 33#endif 34static const char rcsid[] = 35 "$FreeBSD: releng/10.3/usr.sbin/timed/timed/candidate.c 246209 2013-02-01 14:26:54Z charnier $"; 36#endif /* not lint */ 37 38#include "globals.h" 39 40/* 41 * `election' candidates a host as master: it is called by a slave 42 * which runs with the -M option set when its election timeout expires. 43 * Note the conservative approach: if a new timed comes up, or another 44 * candidate sends an election request, the candidature is withdrawn. 45 */ 46int 47election(struct netinfo *net) 48{ 49 struct tsp *resp, msg; 50 struct timeval then, wait; 51 struct tsp *answer; 52 struct hosttbl *htp; 53 char loop_lim = 0; 54 55/* This code can get totally confused if it gets slightly behind. For 56 * example, if readmsg() has some QUIT messages waiting from the last 57 * round, we would send an ELECTION message, get the stale QUIT, 58 * and give up. This results in network storms when several machines 59 * do it at once. 60 */ 61 wait.tv_sec = 0; 62 wait.tv_usec = 0; 63 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) { 64 if (trace) 65 fprintf(fd, "election: discarded stale REFUSE\n"); 66 } 67 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) { 68 if (trace) 69 fprintf(fd, "election: discarded stale QUIT\n"); 70 } 71 72again: 73 syslog(LOG_INFO, "This machine is a candidate time master"); 74 if (trace) 75 fprintf(fd, "This machine is a candidate time master\n"); 76 msg.tsp_type = TSP_ELECTION; 77 msg.tsp_vers = TSPVERSION; 78 (void)strcpy(msg.tsp_name, hostname); 79 bytenetorder(&msg); 80 if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, 81 (struct sockaddr*)&net->dest_addr, 82 sizeof(struct sockaddr)) < 0) { 83 trace_sendto_err(net->dest_addr.sin_addr); 84 return(SLAVE); 85 } 86 87 (void)gettimeofday(&then, 0); 88 then.tv_sec += 3; 89 for (;;) { 90 (void)gettimeofday(&wait, 0); 91 timevalsub(&wait,&then,&wait); 92 resp = readmsg(TSP_ANY, ANYADDR, &wait, net); 93 if (!resp) 94 return(MASTER); 95 96 switch (resp->tsp_type) { 97 98 case TSP_ACCEPT: 99 (void)addmach(resp->tsp_name, &from,fromnet); 100 break; 101 102 case TSP_MASTERUP: 103 case TSP_MASTERREQ: 104 /* 105 * If another timedaemon is coming up at the same 106 * time, give up, and let it be the master. 107 */ 108 if (++loop_lim < 5 109 && !good_host_name(resp->tsp_name)) { 110 (void)addmach(resp->tsp_name, &from,fromnet); 111 suppress(&from, resp->tsp_name, net); 112 goto again; 113 } 114 rmnetmachs(net); 115 return(SLAVE); 116 117 case TSP_QUIT: 118 case TSP_REFUSE: 119 /* 120 * Collision: change value of election timer 121 * using exponential backoff. 122 * 123 * Fooey. 124 * An exponential backoff on a delay starting at 125 * 6 to 15 minutes for a process that takes 126 * milliseconds is silly. It is particularly 127 * strange that the original code would increase 128 * the backoff without bound. 129 */ 130 rmnetmachs(net); 131 return(SLAVE); 132 133 case TSP_ELECTION: 134 /* no master for another round */ 135 htp = addmach(resp->tsp_name,&from,fromnet); 136 msg.tsp_type = TSP_REFUSE; 137 (void)strcpy(msg.tsp_name, hostname); 138 answer = acksend(&msg, &htp->addr, htp->name, 139 TSP_ACK, 0, htp->noanswer); 140 if (!answer) { 141 syslog(LOG_ERR, "error in election from %s", 142 htp->name); 143 } 144 break; 145 146 case TSP_SLAVEUP: 147 (void)addmach(resp->tsp_name, &from,fromnet); 148 break; 149 150 case TSP_SETDATE: 151 case TSP_SETDATEREQ: 152 break; 153 154 default: 155 if (trace) { 156 fprintf(fd, "candidate: "); 157 print(resp, &from); 158 } 159 break; 160 } 161 } 162} 163