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45 * candidate sends an election request, the candidature is withdrawn.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
election(struct netinfo * net)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