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. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35#if 0
36static char sccsid[] = "@(#)candidate.c	8.1 (Berkeley) 6/6/93";
37#endif
38__attribute__((__used__))
39static const char rcsid[] =
40  "$FreeBSD: src/usr.sbin/timed/timed/candidate.c,v 1.5 1999/08/28 01:20:16 peter Exp $";
41#endif /* not lint */
42#include <sys/cdefs.h>
43
44#include "globals.h"
45
46/*
47 * `election' candidates a host as master: it is called by a slave
48 * which runs with the -M option set when its election timeout expires.
49 * Note the conservative approach: if a new timed comes up, or another
50 * candidate sends an election request, the candidature is withdrawn.
51 */
52int
53election(net)
54	struct netinfo *net;
55{
56	struct tsp *resp, msg;
57	struct timeval then, wait;
58	struct tsp *answer;
59	struct hosttbl *htp;
60	char loop_lim = 0;
61
62/* This code can get totally confused if it gets slightly behind.  For
63 *	example, if readmsg() has some QUIT messages waiting from the last
64 *	round, we would send an ELECTION message, get the stale QUIT,
65 *	and give up.  This results in network storms when several machines
66 *	do it at once.
67 */
68	wait.tv_sec = 0;
69	wait.tv_usec = 0;
70	while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
71		if (trace)
72			fprintf(fd, "election: discarded stale REFUSE\n");
73	}
74	while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
75		if (trace)
76			fprintf(fd, "election: discarded stale QUIT\n");
77	}
78
79again:
80	syslog(LOG_INFO, "This machine is a candidate time master");
81	if (trace)
82		fprintf(fd, "This machine is a candidate time master\n");
83	msg.tsp_type = TSP_ELECTION;
84	msg.tsp_vers = TSPVERSION;
85	(void)strcpy(msg.tsp_name, hostname);
86	bytenetorder(&msg);
87	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
88		   (struct sockaddr*)&net->dest_addr,
89		   sizeof(struct sockaddr)) < 0) {
90		trace_sendto_err(net->dest_addr.sin_addr);
91		return(SLAVE);
92	}
93
94	(void)gettimeofday(&then, 0);
95	then.tv_sec += 3;
96	for (;;) {
97		(void)gettimeofday(&wait, 0);
98		timevalsub(&wait,&then,&wait);
99		resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
100		if (!resp)
101			return(MASTER);
102
103		switch (resp->tsp_type) {
104
105		case TSP_ACCEPT:
106			(void)addmach(resp->tsp_name, &from,fromnet);
107			break;
108
109		case TSP_MASTERUP:
110		case TSP_MASTERREQ:
111			/*
112			 * If another timedaemon is coming up at the same
113			 * time, give up, and let it be the master.
114			 */
115			if (++loop_lim < 5
116			    && !good_host_name(resp->tsp_name)) {
117				(void)addmach(resp->tsp_name, &from,fromnet);
118				suppress(&from, resp->tsp_name, net);
119				goto again;
120			}
121			rmnetmachs(net);
122			return(SLAVE);
123
124		case TSP_QUIT:
125		case TSP_REFUSE:
126			/*
127			 * Collision: change value of election timer
128			 * using exponential backoff.
129			 *
130			 *  Fooey.
131			 * An exponential backoff on a delay starting at
132			 * 6 to 15 minutes for a process that takes
133			 * milliseconds is silly.  It is particularly
134			 * strange that the original code would increase
135			 * the backoff without bound.
136			 */
137			rmnetmachs(net);
138			return(SLAVE);
139
140		case TSP_ELECTION:
141			/* no master for another round */
142			htp = addmach(resp->tsp_name,&from,fromnet);
143			msg.tsp_type = TSP_REFUSE;
144			(void)strcpy(msg.tsp_name, hostname);
145			answer = acksend(&msg, &htp->addr, htp->name,
146					 TSP_ACK, 0, htp->noanswer);
147			if (!answer) {
148				syslog(LOG_ERR, "error in election from %s",
149				       htp->name);
150			}
151			break;
152
153		case TSP_SLAVEUP:
154			(void)addmach(resp->tsp_name, &from,fromnet);
155			break;
156
157		case TSP_SETDATE:
158		case TSP_SETDATEREQ:
159			break;
160
161		default:
162			if (trace) {
163				fprintf(fd, "candidate: ");
164				print(resp, &from);
165			}
166			break;
167		}
168	}
169}
170