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 * 3. 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 #include <sys/cdefs.h> 31 #ifndef lint 32 #if 0 33 static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93"; 34 #else 35 __RCSID("$NetBSD: candidate.c,v 1.12 2007/01/26 16:12:41 christos Exp $"); 36 #endif 37 #endif /* not lint */ 38 39 #include "globals.h" 40 41 /* 42 * `election' candidates a host as master: it is called by a slave 43 * which runs with the -M option set when its election timeout expires. 44 * Note the conservative approach: if a new timed comes up, or another 45 * candidate sends an election request, the candidature is withdrawn. 46 */ 47 int 48 election(struct netinfo *net) 49 { 50 struct tsp *resp, msg; 51 struct timeval then, wait; 52 struct tsp *answer; 53 struct hosttbl *htp; 54 char loop_lim = 0; 55 56 /* This code can get totally confused if it gets slightly behind. For 57 * example, if readmsg() has some QUIT messages waiting from the last 58 * round, we would send an ELECTION message, get the stale QUIT, 59 * and give up. This results in network storms when several machines 60 * do it at once. 61 */ 62 wait.tv_sec = 0; 63 wait.tv_usec = 0; 64 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) { 65 if (trace) 66 fprintf(fd, "election: discarded stale REFUSE\n"); 67 } 68 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) { 69 if (trace) 70 fprintf(fd, "election: discarded stale QUIT\n"); 71 } 72 73 again: 74 syslog(LOG_INFO, "This machine is a candidate time master"); 75 if (trace) 76 fprintf(fd, "This machine is a candidate time master\n"); 77 msg.tsp_type = TSP_ELECTION; 78 msg.tsp_vers = TSPVERSION; 79 set_tsp_name(&msg, hostname); 80 bytenetorder(&msg); 81 if (sendtsp(sock, &msg, &net->dest_addr) == -1) 82 return(SLAVE); 83 84 (void)gettimeofday(&then, 0); 85 then.tv_sec += 3; 86 for (;;) { 87 (void)gettimeofday(&wait, 0); 88 timersub(&then, &wait, &wait); 89 resp = readmsg(TSP_ANY, ANYADDR, &wait, net); 90 if (!resp) 91 return(MASTER); 92 93 switch (resp->tsp_type) { 94 95 case TSP_ACCEPT: 96 (void)addmach(resp->tsp_name, &from,fromnet); 97 break; 98 99 case TSP_MASTERUP: 100 case TSP_MASTERREQ: 101 /* 102 * If another timedaemon is coming up at the same 103 * time, give up, and let it be the master. 104 */ 105 if (++loop_lim < 5 106 && !good_host_name(resp->tsp_name)) { 107 (void)addmach(resp->tsp_name, &from,fromnet); 108 suppress(&from, resp->tsp_name, net); 109 goto again; 110 } 111 rmnetmachs(net); 112 return(SLAVE); 113 114 case TSP_QUIT: 115 case TSP_REFUSE: 116 /* 117 * Collision: change value of election timer 118 * using exponential backoff. 119 * 120 * Fooey. 121 * An exponential backoff on a delay starting at 122 * 6 to 15 minutes for a process that takes 123 * milliseconds is silly. It is particularly 124 * strange that the original code would increase 125 * the backoff without bound. 126 */ 127 rmnetmachs(net); 128 return(SLAVE); 129 130 case TSP_ELECTION: 131 /* no master for another round */ 132 htp = addmach(resp->tsp_name,&from,fromnet); 133 msg.tsp_type = TSP_REFUSE; 134 set_tsp_name(&msg, hostname); 135 answer = acksend(&msg, &htp->addr, htp->name, 136 TSP_ACK, 0, htp->noanswer); 137 if (!answer) { 138 syslog(LOG_ERR, "error in election from %s", 139 htp->name); 140 } 141 break; 142 143 case TSP_SLAVEUP: 144 (void)addmach(resp->tsp_name, &from,fromnet); 145 break; 146 147 case TSP_SETDATE: 148 case TSP_SETDATEREQ: 149 break; 150 151 default: 152 if (trace) { 153 fprintf(fd, "candidate: "); 154 print(resp, &from); 155 } 156 break; 157 } 158 } 159 } 160