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
33static char sccsid[] = "@(#)candidate.c	8.1 (Berkeley) 6/6/93";
34#else
35__RCSID("$NetBSD: candidate.c,v 1.11 2007/01/25 23:25:20 cbiere 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45 * candidate sends an election request, the candidature is withdrawn.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 */
47int
48election(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
73again:
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