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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 #ifndef lint 36 #if 0 37 static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93"; 38 #else 39 __RCSID("$NetBSD: candidate.c,v 1.8 2002/07/06 22:08:31 wiz Exp $"); 40 #endif 41 #endif /* not lint */ 42 43 #include "globals.h" 44 45 /* 46 * `election' candidates a host as master: it is called by a slave 47 * which runs with the -M option set when its election timeout expires. 48 * Note the conservative approach: if a new timed comes up, or another 49 * candidate sends an election request, the candidature is withdrawn. 50 */ 51 int 52 election(struct netinfo *net) 53 { 54 struct tsp *resp, msg; 55 struct timeval then, wait; 56 struct tsp *answer; 57 struct hosttbl *htp; 58 char loop_lim = 0; 59 60 /* This code can get totally confused if it gets slightly behind. For 61 * example, if readmsg() has some QUIT messages waiting from the last 62 * round, we would send an ELECTION message, get the stale QUIT, 63 * and give up. This results in network storms when several machines 64 * do it at once. 65 */ 66 wait.tv_sec = 0; 67 wait.tv_usec = 0; 68 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) { 69 if (trace) 70 fprintf(fd, "election: discarded stale REFUSE\n"); 71 } 72 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) { 73 if (trace) 74 fprintf(fd, "election: discarded stale QUIT\n"); 75 } 76 77 again: 78 syslog(LOG_INFO, "This machine is a candidate time master"); 79 if (trace) 80 fprintf(fd, "This machine is a candidate time master\n"); 81 msg.tsp_type = TSP_ELECTION; 82 msg.tsp_vers = TSPVERSION; 83 (void)strcpy(msg.tsp_name, hostname); 84 bytenetorder(&msg); 85 if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, 86 (struct sockaddr*)&net->dest_addr, 87 sizeof(struct sockaddr)) < 0) { 88 trace_sendto_err(net->dest_addr.sin_addr); 89 return(SLAVE); 90 } 91 92 (void)gettimeofday(&then, 0); 93 then.tv_sec += 3; 94 for (;;) { 95 (void)gettimeofday(&wait, 0); 96 timersub(&then, &wait, &wait); 97 resp = readmsg(TSP_ANY, ANYADDR, &wait, net); 98 if (!resp) 99 return(MASTER); 100 101 switch (resp->tsp_type) { 102 103 case TSP_ACCEPT: 104 (void)addmach(resp->tsp_name, &from,fromnet); 105 break; 106 107 case TSP_MASTERUP: 108 case TSP_MASTERREQ: 109 /* 110 * If another timedaemon is coming up at the same 111 * time, give up, and let it be the master. 112 */ 113 if (++loop_lim < 5 114 && !good_host_name(resp->tsp_name)) { 115 (void)addmach(resp->tsp_name, &from,fromnet); 116 suppress(&from, resp->tsp_name, net); 117 goto again; 118 } 119 rmnetmachs(net); 120 return(SLAVE); 121 122 case TSP_QUIT: 123 case TSP_REFUSE: 124 /* 125 * Collision: change value of election timer 126 * using exponential backoff. 127 * 128 * Fooey. 129 * An exponential backoff on a delay starting at 130 * 6 to 15 minutes for a process that takes 131 * milliseconds is silly. It is particularly 132 * strange that the original code would increase 133 * the backoff without bound. 134 */ 135 rmnetmachs(net); 136 return(SLAVE); 137 138 case TSP_ELECTION: 139 /* no master for another round */ 140 htp = addmach(resp->tsp_name,&from,fromnet); 141 msg.tsp_type = TSP_REFUSE; 142 (void)strcpy(msg.tsp_name, hostname); 143 answer = acksend(&msg, &htp->addr, htp->name, 144 TSP_ACK, 0, htp->noanswer); 145 if (!answer) { 146 syslog(LOG_ERR, "error in election from %s", 147 htp->name); 148 } 149 break; 150 151 case TSP_SLAVEUP: 152 (void)addmach(resp->tsp_name, &from,fromnet); 153 break; 154 155 case TSP_SETDATE: 156 case TSP_SETDATEREQ: 157 break; 158 159 default: 160 if (trace) { 161 fprintf(fd, "candidate: "); 162 print(resp, &from); 163 } 164 break; 165 } 166 } 167 } 168