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29 * @(#)candidate.c 8.1 (Berkeley) 6/6/93
30 * $FreeBSD: src/usr.sbin/timed/timed/candidate.c,v 1.5 1999/08/28 01:20:16 peter Exp $
31 * $DragonFly: src/usr.sbin/timed/timed/candidate.c,v 1.5 2004/09/05 02:20:15 dillon Exp $
37 * `election' candidates a host as master: it is called by a slave
38 * which runs with the -M option set when its election timeout expires.
39 * Note the conservative approach: if a new timed comes up, or another
40 * candidate sends an election request, the candidature is withdrawn.
43 election(struct netinfo *net)
45 struct tsp *resp, msg;
46 struct timeval then, wait;
51 /* This code can get totally confused if it gets slightly behind. For
52 * example, if readmsg() has some QUIT messages waiting from the last
53 * round, we would send an ELECTION message, get the stale QUIT,
54 * and give up. This results in network storms when several machines
59 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
61 fprintf(fd, "election: discarded stale REFUSE\n");
63 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
65 fprintf(fd, "election: discarded stale QUIT\n");
69 syslog(LOG_INFO, "This machine is a candidate time master");
71 fprintf(fd, "This machine is a candidate time master\n");
72 msg.tsp_type = TSP_ELECTION;
73 msg.tsp_vers = TSPVERSION;
74 strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
76 if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
77 (struct sockaddr*)&net->dest_addr,
78 sizeof(struct sockaddr)) < 0) {
79 trace_sendto_err(net->dest_addr.sin_addr);
83 gettimeofday(&then, 0);
86 gettimeofday(&wait, 0);
87 timevalsub(&wait,&then,&wait);
88 resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
92 switch (resp->tsp_type) {
95 addmach(resp->tsp_name, &from,fromnet);
101 * If another timedaemon is coming up at the same
102 * time, give up, and let it be the master.
105 && !good_host_name(resp->tsp_name)) {
106 addmach(resp->tsp_name, &from,fromnet);
107 suppress(&from, resp->tsp_name, net);
116 * Collision: change value of election timer
117 * using exponential backoff.
120 * An exponential backoff on a delay starting at
121 * 6 to 15 minutes for a process that takes
122 * milliseconds is silly. It is particularly
123 * strange that the original code would increase
124 * the backoff without bound.
130 /* no master for another round */
131 htp = addmach(resp->tsp_name,&from,fromnet);
132 msg.tsp_type = TSP_REFUSE;
133 strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
134 answer = acksend(&msg, &htp->addr, htp->name,
135 TSP_ACK, 0, htp->noanswer);
137 syslog(LOG_ERR, "error in election from %s",
143 addmach(resp->tsp_name, &from,fromnet);
152 fprintf(fd, "candidate: ");