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 * 4. 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#ifndef lint
31#if 0
32static char sccsid[] = "@(#)candidate.c	8.1 (Berkeley) 6/6/93";
33#endif
34static const char rcsid[] =
35  "$FreeBSD$";
36#endif /* not lint */
37
38#include "globals.h"
39
40/*
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44 * candidate sends an election request, the candidature is withdrawn.
45 */
46int
47election(struct netinfo *net)
48{
49	struct tsp *resp, msg;
50	struct timeval then, wait;
51	struct tsp *answer;
52	struct hosttbl *htp;
53	char loop_lim = 0;
54
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
59 *	do it at once.
60 */
61	wait.tv_sec = 0;
62	wait.tv_usec = 0;
63	while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
64		if (trace)
65			fprintf(fd, "election: discarded stale REFUSE\n");
66	}
67	while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
68		if (trace)
69			fprintf(fd, "election: discarded stale QUIT\n");
70	}
71
72again:
73	syslog(LOG_INFO, "This machine is a candidate time master");
74	if (trace)
75		fprintf(fd, "This machine is a candidate time master\n");
76	msg.tsp_type = TSP_ELECTION;
77	msg.tsp_vers = TSPVERSION;
78	(void)strcpy(msg.tsp_name, hostname);
79	bytenetorder(&msg);
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);
84		return(SLAVE);
85	}
86
87	(void)gettimeofday(&then, 0);
88	then.tv_sec += 3;
89	for (;;) {
90		(void)gettimeofday(&wait, 0);
91		timevalsub(&wait,&then,&wait);
92		resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
93		if (!resp)
94			return(MASTER);
95
96		switch (resp->tsp_type) {
97
98		case TSP_ACCEPT:
99			(void)addmach(resp->tsp_name, &from,fromnet);
100			break;
101
102		case TSP_MASTERUP:
103		case TSP_MASTERREQ:
104			/*
105			 * If another timedaemon is coming up at the same
106			 * time, give up, and let it be the master.
107			 */
108			if (++loop_lim < 5
109			    && !good_host_name(resp->tsp_name)) {
110				(void)addmach(resp->tsp_name, &from,fromnet);
111				suppress(&from, resp->tsp_name, net);
112				goto again;
113			}
114			rmnetmachs(net);
115			return(SLAVE);
116
117		case TSP_QUIT:
118		case TSP_REFUSE:
119			/*
120			 * Collision: change value of election timer
121			 * using exponential backoff.
122			 *
123			 *  Fooey.
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.
129			 */
130			rmnetmachs(net);
131			return(SLAVE);
132
133		case TSP_ELECTION:
134			/* no master for another round */
135			htp = addmach(resp->tsp_name,&from,fromnet);
136			msg.tsp_type = TSP_REFUSE;
137			(void)strcpy(msg.tsp_name, hostname);
138			answer = acksend(&msg, &htp->addr, htp->name,
139					 TSP_ACK, 0, htp->noanswer);
140			if (!answer) {
141				syslog(LOG_ERR, "error in election from %s",
142				       htp->name);
143			}
144			break;
145
146		case TSP_SLAVEUP:
147			(void)addmach(resp->tsp_name, &from,fromnet);
148			break;
149
150		case TSP_SETDATE:
151		case TSP_SETDATEREQ:
152			break;
153
154		default:
155			if (trace) {
156				fprintf(fd, "candidate: ");
157				print(resp, &from);
158			}
159			break;
160		}
161	}
162}
163