[apple/network_cmds.git] / timed.tproj / timed.tproj / candidate.c

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.0 (the 'License').  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License."
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*-
 * Copyright (c) 1985, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)candidate.c	8.1 (Berkeley) 6/6/93";
#endif /* not lint */

#ifdef sgi
#ident "$Revision: 1.1.1.1 $"
#endif

#include "globals.h"

/*
 * `election' candidates a host as master: it is called by a slave
 * which runs with the -M option set when its election timeout expires.
 * Note the conservative approach: if a new timed comes up, or another
 * candidate sends an election request, the candidature is withdrawn.
 */
int
election(net)
	struct netinfo *net;
{
	struct tsp *resp, msg;
	struct timeval then, wait;
	struct tsp *answer;
	struct hosttbl *htp;
	char loop_lim = 0;

/* This code can get totally confused if it gets slightly behind.  For
 *	example, if readmsg() has some QUIT messages waiting from the last
 *	round, we would send an ELECTION message, get the stale QUIT,
 *	and give up.  This results in network storms when several machines
 *	do it at once.
 */
	wait.tv_sec = 0;
	wait.tv_usec = 0;
	while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
		if (trace)
			fprintf(fd, "election: discarded stale REFUSE\n");
	}
	while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
		if (trace)
			fprintf(fd, "election: discarded stale QUIT\n");
	}

again:
	syslog(LOG_INFO, "This machine is a candidate time master");
	if (trace)
		fprintf(fd, "This machine is a candidate time master\n");
	msg.tsp_type = TSP_ELECTION;
	msg.tsp_vers = TSPVERSION;
	(void)strcpy(msg.tsp_name, hostname);
	bytenetorder(&msg);
	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
		   (struct sockaddr*)&net->dest_addr,
		   sizeof(struct sockaddr)) < 0) {
		trace_sendto_err(net->dest_addr.sin_addr);
		return(SLAVE);
	}

	(void)gettimeofday(&then, 0);
	then.tv_sec += 3;
	for (;;) {
		(void)gettimeofday(&wait, 0);
		timevalsub(&wait,&then,&wait);
		resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
		if (!resp)
			return(MASTER);

		switch (resp->tsp_type) {

		case TSP_ACCEPT:
			(void)addmach(resp->tsp_name, &from,fromnet);
			break;

		case TSP_MASTERUP:
		case TSP_MASTERREQ:
			/*
			 * If another timedaemon is coming up at the same
			 * time, give up, and let it be the master.
			 */
			if (++loop_lim < 5
			    && !good_host_name(resp->tsp_name)) {
				(void)addmach(resp->tsp_name, &from,fromnet);
				suppress(&from, resp->tsp_name, net);
				goto again;
			}
			rmnetmachs(net);
			return(SLAVE);

		case TSP_QUIT:
		case TSP_REFUSE:
			/*
			 * Collision: change value of election timer
			 * using exponential backoff. 
			 *
			 *  Fooey.
			 * An exponential backoff on a delay starting at
			 * 6 to 15 minutes for a process that takes
			 * milliseconds is silly.  It is particularly
			 * strange that the original code would increase
			 * the backoff without bound.
			 */
			rmnetmachs(net);
			return(SLAVE);

		case TSP_ELECTION:
			/* no master for another round */
			htp = addmach(resp->tsp_name,&from,fromnet);
			msg.tsp_type = TSP_REFUSE;
			(void)strcpy(msg.tsp_name, hostname);
			answer = acksend(&msg, &htp->addr, htp->name,
					 TSP_ACK, 0, htp->noanswer);
			if (!answer) {
				syslog(LOG_ERR, "error in election from %s",
				       htp->name);
			}
			break;

		case TSP_SLAVEUP:
			(void)addmach(resp->tsp_name, &from,fromnet);
			break;

		case TSP_SETDATE:
		case TSP_SETDATEREQ:
			break;

		default:
			if (trace) {
				fprintf(fd, "candidate: ");
				print(resp, &from);
			}
			break;
		}
	}
}
Commit	Line	Data
b7080c8e A	1	/*
	2	* Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
2b484d24 A	6	* "Portions Copyright (c) 1999 Apple Computer, Inc. All Rights
	7	* Reserved. This file contains Original Code and/or Modifications of
	8	* Original Code as defined in and that are subject to the Apple Public
	9	* Source License Version 1.0 (the 'License'). You may not use this file
	10	* except in compliance with the License. Please obtain a copy of the
	11	* License at http://www.apple.com/publicsource and read it before using
	12	* this file.
b7080c8e A	13	*
	14	* The Original Code and all software distributed under the License are
	15	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	16	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	17	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2b484d24 A	18	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	19	* License for the specific language governing rights and limitations
	20	* under the License."
b7080c8e A	21	*
	22	* @APPLE_LICENSE_HEADER_END@
	23	*/
	24	/*-
	25	* Copyright (c) 1985, 1993
	26	* The Regents of the University of California. All rights reserved.
	27	*
	28	* Redistribution and use in source and binary forms, with or without
	29	* modification, are permitted provided that the following conditions
	30	* are met:
	31	* 1. Redistributions of source code must retain the above copyright
	32	* notice, this list of conditions and the following disclaimer.
	33	* 2. Redistributions in binary form must reproduce the above copyright
	34	* notice, this list of conditions and the following disclaimer in the
	35	* documentation and/or other materials provided with the distribution.
	36	* 3. All advertising materials mentioning features or use of this software
	37	* must display the following acknowledgement:
	38	* This product includes software developed by the University of
	39	* California, Berkeley and its contributors.
	40	* 4. Neither the name of the University nor the names of its contributors
	41	* may be used to endorse or promote products derived from this software
	42	* without specific prior written permission.
	43	*
	44	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	45	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	46	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	47	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	48	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	49	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	50	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	51	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	52	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	53	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	54	* SUCH DAMAGE.
	55	*/
	56
	57	#ifndef lint
	58	static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93";
	59	#endif /* not lint */
	60
	61	#ifdef sgi
	62	#ident "$Revision: 1.1.1.1 $"
	63	#endif
	64
	65	#include "globals.h"
	66
	67	/*
	68	* `election' candidates a host as master: it is called by a slave
	69	* which runs with the -M option set when its election timeout expires.
	70	* Note the conservative approach: if a new timed comes up, or another
	71	* candidate sends an election request, the candidature is withdrawn.
	72	*/
	73	int
	74	election(net)
	75	struct netinfo *net;
	76	{
	77	struct tsp *resp, msg;
	78	struct timeval then, wait;
	79	struct tsp *answer;
	80	struct hosttbl *htp;
	81	char loop_lim = 0;
	82
	83	/* This code can get totally confused if it gets slightly behind. For
	84	* example, if readmsg() has some QUIT messages waiting from the last
85	* round, we would send an ELECTION message, get the stale QUIT,
86	* and give up. This results in network storms when several machines
87	* do it at once.
88	*/
89	wait.tv_sec = 0;
90	wait.tv_usec = 0;
91	while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
92	if (trace)
93	fprintf(fd, "election: discarded stale REFUSE\n");
94	}
95	while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
96	if (trace)
97	fprintf(fd, "election: discarded stale QUIT\n");
98	}
99
100	again:
101	syslog(LOG_INFO, "This machine is a candidate time master");
102	if (trace)
103	fprintf(fd, "This machine is a candidate time master\n");
104	msg.tsp_type = TSP_ELECTION;
105	msg.tsp_vers = TSPVERSION;
106	(void)strcpy(msg.tsp_name, hostname);
107	bytenetorder(&msg);
108	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
109	(struct sockaddr*)&net->dest_addr,
110	sizeof(struct sockaddr)) < 0) {
111	trace_sendto_err(net->dest_addr.sin_addr);
112	return(SLAVE);
113	}
114
115	(void)gettimeofday(&then, 0);
116	then.tv_sec += 3;
117	for (;;) {
118	(void)gettimeofday(&wait, 0);
119	timevalsub(&wait,&then,&wait);
120	resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
121	if (!resp)
122	return(MASTER);
123
124	switch (resp->tsp_type) {
125
126	case TSP_ACCEPT:
127	(void)addmach(resp->tsp_name, &from,fromnet);
128	break;
129
130	case TSP_MASTERUP:
131	case TSP_MASTERREQ:
132	/*
133	* If another timedaemon is coming up at the same
134	* time, give up, and let it be the master.
135	*/
136	if (++loop_lim < 5
137	&& !good_host_name(resp->tsp_name)) {
138	(void)addmach(resp->tsp_name, &from,fromnet);
139	suppress(&from, resp->tsp_name, net);
140	goto again;
141	}
142	rmnetmachs(net);
143	return(SLAVE);
144
145	case TSP_QUIT:
146	case TSP_REFUSE:
147	/*
148	* Collision: change value of election timer
149	* using exponential backoff.
150	*
151	* Fooey.
152	* An exponential backoff on a delay starting at
153	* 6 to 15 minutes for a process that takes
154	* milliseconds is silly. It is particularly
155	* strange that the original code would increase
156	* the backoff without bound.
157	*/
158	rmnetmachs(net);
159	return(SLAVE);
160
161	case TSP_ELECTION:
162	/* no master for another round */
163	htp = addmach(resp->tsp_name,&from,fromnet);
164	msg.tsp_type = TSP_REFUSE;
165	(void)strcpy(msg.tsp_name, hostname);
166	answer = acksend(&msg, &htp->addr, htp->name,
167	TSP_ACK, 0, htp->noanswer);
168	if (!answer) {
169	syslog(LOG_ERR, "error in election from %s",
170	htp->name);
171	}
172	break;
173
174	case TSP_SLAVEUP:
175	(void)addmach(resp->tsp_name, &from,fromnet);
176	break;
177
178	case TSP_SETDATE:
179	case TSP_SETDATEREQ:
180	break;
181
182	default:
183	if (trace) {
184	fprintf(fd, "candidate: ");
185	print(resp, &from);
186	}
187	break;
188	}
189	}
190	}