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 1.7 2001/09/02 00:13:05 reinoud 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conservative approach: if a new timed comes up, or another 49 * candidate sends an election request, the candidature is withdrawn. 50 */ 51 int 52 election(net) 53 struct netinfo *net; 54 { 55 struct tsp *resp, msg; 56 struct timeval then, wait; 57 struct tsp *answer; 58 struct hosttbl *htp; 59 char loop_lim = 0; 60 61 /* This code can get totally confused if it gets slightly behind. For 62 * example, if readmsg() has some QUIT messages waiting from the last 63 * round, we would send an ELECTION message, get the stale QUIT, 64 * and give up. This results in network storms when several machines 65 * do it at once. 66 */ 67 wait.tv_sec = 0; 68 wait.tv_usec = 0; 69 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) { 70 if (trace) 71 fprintf(fd, "election: discarded stale REFUSE\n"); 72 } 73 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) { 74 if (trace) 75 fprintf(fd, "election: discarded stale QUIT\n"); 76 } 77 78 again: 79 syslog(LOG_INFO, "This machine is a candidate time master"); 80 if (trace) 81 fprintf(fd, "This machine is a candidate time master\n"); 82 msg.tsp_type = TSP_ELECTION; 83 msg.tsp_vers = TSPVERSION; 84 (void)strcpy(msg.tsp_name, hostname); 85 bytenetorder(&msg); 86 if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, 87 (struct sockaddr*)&net->dest_addr, 88 sizeof(struct sockaddr)) < 0) { 89 trace_sendto_err(net->dest_addr.sin_addr); 90 return(SLAVE); 91 } 92 93 (void)gettimeofday(&then, 0); 94 then.tv_sec += 3; 95 for (;;) { 96 (void)gettimeofday(&wait, 0); 97 timersub(&then, &wait, &wait); 98 resp = readmsg(TSP_ANY, ANYADDR, &wait, net); 99 if (!resp) 100 return(MASTER); 101 102 switch (resp->tsp_type) { 103 104 case TSP_ACCEPT: 105 (void)addmach(resp->tsp_name, &from,fromnet); 106 break; 107 108 case TSP_MASTERUP: 109 case TSP_MASTERREQ: 110 /* 111 * If another timedaemon is coming up at the same 112 * time, give up, and let it be the master. 113 */ 114 if (++loop_lim < 5 115 && !good_host_name(resp->tsp_name)) { 116 (void)addmach(resp->tsp_name, &from,fromnet); 117 suppress(&from, resp->tsp_name, net); 118 goto again; 119 } 120 rmnetmachs(net); 121 return(SLAVE); 122 123 case TSP_QUIT: 124 case TSP_REFUSE: 125 /* 126 * Collision: change value of election timer 127 * using exponential backoff. 128 * 129 * Fooey. 130 * An exponential backoff on a delay starting at 131 * 6 to 15 minutes for a process that takes 132 * milliseconds is silly. It is particularly 133 * strange that the original code would increase 134 * the backoff without bound. 135 */ 136 rmnetmachs(net); 137 return(SLAVE); 138 139 case TSP_ELECTION: 140 /* no master for another round */ 141 htp = addmach(resp->tsp_name,&from,fromnet); 142 msg.tsp_type = TSP_REFUSE; 143 (void)strcpy(msg.tsp_name, hostname); 144 answer = acksend(&msg, &htp->addr, htp->name, 145 TSP_ACK, 0, htp->noanswer); 146 if (!answer) { 147 syslog(LOG_ERR, "error in election from %s", 148 htp->name); 149 } 150 break; 151 152 case TSP_SLAVEUP: 153 (void)addmach(resp->tsp_name, &from,fromnet); 154 break; 155 156 case TSP_SETDATE: 157 case TSP_SETDATEREQ: 158 break; 159 160 default: 161 if (trace) { 162 fprintf(fd, "candidate: "); 163 print(resp, &from); 164 } 165 break; 166 } 167 } 168 } 169