1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1985, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #ifndef lint
33 #if 0
34 static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93";
35 #endif
36 static const char rcsid[] =
37 "$FreeBSD$";
38 #endif /* not lint */
39
40 #include "globals.h"
41
42 /*
43 * `election' candidates a host as master: it is called by a slave
44 * which runs with the -M option set when its election timeout expires.
45 * Note the conservative approach: if a new timed comes up, or another
46 * candidate sends an election request, the candidature is withdrawn.
47 */
48 int
election(struct netinfo * net)49 election(struct netinfo *net)
50 {
51 struct tsp *resp, msg;
52 struct timeval then, wait;
53 struct tsp *answer;
54 struct hosttbl *htp;
55 char loop_lim = 0;
56
57 /* This code can get totally confused if it gets slightly behind. For
58 * example, if readmsg() has some QUIT messages waiting from the last
59 * round, we would send an ELECTION message, get the stale QUIT,
60 * and give up. This results in network storms when several machines
61 * do it at once.
62 */
63 wait.tv_sec = 0;
64 wait.tv_usec = 0;
65 while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
66 if (trace)
67 fprintf(fd, "election: discarded stale REFUSE\n");
68 }
69 while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
70 if (trace)
71 fprintf(fd, "election: discarded stale QUIT\n");
72 }
73
74 again:
75 syslog(LOG_INFO, "This machine is a candidate time master");
76 if (trace)
77 fprintf(fd, "This machine is a candidate time master\n");
78 msg.tsp_type = TSP_ELECTION;
79 msg.tsp_vers = TSPVERSION;
80 (void)strcpy(msg.tsp_name, hostname);
81 bytenetorder(&msg);
82 if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
83 (struct sockaddr*)&net->dest_addr,
84 sizeof(struct sockaddr)) < 0) {
85 trace_sendto_err(net->dest_addr.sin_addr);
86 return(SLAVE);
87 }
88
89 (void)gettimeofday(&then, 0);
90 then.tv_sec += 3;
91 for (;;) {
92 (void)gettimeofday(&wait, 0);
93 timevalsub(&wait,&then,&wait);
94 resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
95 if (!resp)
96 return(MASTER);
97
98 switch (resp->tsp_type) {
99
100 case TSP_ACCEPT:
101 (void)addmach(resp->tsp_name, &from,fromnet);
102 break;
103
104 case TSP_MASTERUP:
105 case TSP_MASTERREQ:
106 /*
107 * If another timedaemon is coming up at the same
108 * time, give up, and let it be the master.
109 */
110 if (++loop_lim < 5
111 && !good_host_name(resp->tsp_name)) {
112 (void)addmach(resp->tsp_name, &from,fromnet);
113 suppress(&from, resp->tsp_name, net);
114 goto again;
115 }
116 rmnetmachs(net);
117 return(SLAVE);
118
119 case TSP_QUIT:
120 case TSP_REFUSE:
121 /*
122 * Collision: change value of election timer
123 * using exponential backoff.
124 *
125 * Fooey.
126 * An exponential backoff on a delay starting at
127 * 6 to 15 minutes for a process that takes
128 * milliseconds is silly. It is particularly
129 * strange that the original code would increase
130 * the backoff without bound.
131 */
132 rmnetmachs(net);
133 return(SLAVE);
134
135 case TSP_ELECTION:
136 /* no master for another round */
137 htp = addmach(resp->tsp_name,&from,fromnet);
138 msg.tsp_type = TSP_REFUSE;
139 (void)strcpy(msg.tsp_name, hostname);
140 answer = acksend(&msg, &htp->addr, htp->name,
141 TSP_ACK, 0, htp->noanswer);
142 if (!answer) {
143 syslog(LOG_ERR, "error in election from %s",
144 htp->name);
145 }
146 break;
147
148 case TSP_SLAVEUP:
149 (void)addmach(resp->tsp_name, &from,fromnet);
150 break;
151
152 case TSP_SETDATE:
153 case TSP_SETDATEREQ:
154 break;
155
156 default:
157 if (trace) {
158 fprintf(fd, "candidate: ");
159 print(resp, &from);
160 }
161 break;
162 }
163 }
164 }
165