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33 * @(#)candidate.c 8.1 (Berkeley) 6/6/93
34 * $FreeBSD: src/usr.sbin/timed/timed/candidate.c,v 1.5 1999/08/28 01:20:16 peter Exp $
35 * $DragonFly: src/usr.sbin/timed/timed/candidate.c,v 1.5 2004/09/05 02:20:15 dillon Exp $
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44 * candidate sends an election request, the candidature is withdrawn.
47 election(struct netinfo *net)
49 struct tsp *resp, msg;
50 struct timeval then, wait;
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
63 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
65 fprintf(fd, "election: discarded stale REFUSE\n");
67 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
69 fprintf(fd, "election: discarded stale QUIT\n");
73 syslog(LOG_INFO, "This machine is a candidate time master");
75 fprintf(fd, "This machine is a candidate time master\n");
76 msg.tsp_type = TSP_ELECTION;
77 msg.tsp_vers = TSPVERSION;
78 strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
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);
87 gettimeofday(&then, 0);
90 gettimeofday(&wait, 0);
91 timevalsub(&wait,&then,&wait);
92 resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
96 switch (resp->tsp_type) {
99 addmach(resp->tsp_name, &from,fromnet);
105 * If another timedaemon is coming up at the same
106 * time, give up, and let it be the master.
109 && !good_host_name(resp->tsp_name)) {
110 addmach(resp->tsp_name, &from,fromnet);
111 suppress(&from, resp->tsp_name, net);
120 * Collision: change value of election timer
121 * using exponential backoff.
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.
134 /* no master for another round */
135 htp = addmach(resp->tsp_name,&from,fromnet);
136 msg.tsp_type = TSP_REFUSE;
137 strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
138 answer = acksend(&msg, &htp->addr, htp->name,
139 TSP_ACK, 0, htp->noanswer);
141 syslog(LOG_ERR, "error in election from %s",
147 addmach(resp->tsp_name, &from,fromnet);
156 fprintf(fd, "candidate: ");