master.c

早期freebsd实现

/*-
 * 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[] = "@(#)master.c	8.1 (Berkeley) 6/6/93";
#endif /* not lint */

#ifdef sgi
#ident "$Revision: 1.21 $"
#endif

#include "globals.h"
#include <sys/file.h>
#include <sys/types.h>
#include <sys/times.h>
#include <setjmp.h>
#ifdef sgi
#include <sys/schedctl.h>
#endif /* sgi */
#include <utmp.h>
#include "pathnames.h"

extern int measure_delta;
extern jmp_buf jmpenv;
extern int Mflag;
extern int justquit;

static int dictate;
static int slvcount;			/* slaves listening to our clock */

static void mchgdate __P((struct tsp *));

#ifdef sgi
extern void logwtmp __P((struct timeval *, struct timeval *));
#else
extern void logwtmp __P((char *, char *, char *));
#endif /* sgi */

/*
 * The main function of `master' is to periodically compute the differences
 * (deltas) between its clock and the clocks of the slaves, to compute the
 * network average delta, and to send to the slaves the differences between
 * their individual deltas and the network delta.
 * While waiting, it receives messages from the slaves (i.e. requests for
 * master's name, remote requests to set the network time, ...), and
 * takes the appropriate action.
 */
int
master()
{
	struct hosttbl *htp;
	long pollingtime;
#define POLLRATE 4
	int polls;
	struct timeval wait, ntime;
	struct tsp *msg, *answer, to;
	char newdate[32];
	struct sockaddr_in taddr;
	char tname[MAXHOSTNAMELEN];
	struct netinfo *ntp;
	int i;

	syslog(LOG_NOTICE, "This machine is master");
	if (trace)
		fprintf(fd, "This machine is master\n");
	for (ntp = nettab; ntp != NULL; ntp = ntp->next) {
		if (ntp->status == MASTER)
			masterup(ntp);
	}
	(void)gettimeofday(&ntime, 0);
	pollingtime = ntime.tv_sec+3;
	if (justquit)
		polls = 0;
	else
		polls = POLLRATE-1;

/* Process all outstanding messages before spending the long time necessary
 *	to update all timers.
 */
loop:
	(void)gettimeofday(&ntime, 0);
	wait.tv_sec = pollingtime - ntime.tv_sec;
	if (wait.tv_sec < 0)
		wait.tv_sec = 0;
	wait.tv_usec = 0;
	msg = readmsg(TSP_ANY, ANYADDR, &wait, 0);
	if (!msg) {
		(void)gettimeofday(&ntime, 0);
		if (ntime.tv_sec >= pollingtime) {
			pollingtime = ntime.tv_sec + SAMPLEINTVL;
			get_goodgroup(0);

/* If a bogus master told us to quit, we can have decided to ignore a
 * network.  Therefore, periodically try to take over everything.
 */
			polls = (polls + 1) % POLLRATE;
			if (0 == polls && nignorednets > 0) {
				trace_msg("Looking for nets to re-master\n");
				for (ntp = nettab; ntp; ntp = ntp->next) {
					if (ntp->status == IGNORE
					    || ntp->status == NOMASTER) {
						lookformaster(ntp);
						if (ntp->status == MASTER) {
							masterup(ntp);
							polls = POLLRATE-1;
						}
					}
					if (ntp->status == MASTER
					    && --ntp->quit_count < 0)
						ntp->quit_count = 0;
				}
				if (polls != 0)
					setstatus();
			}

			synch(0L);

			for (ntp = nettab; ntp != NULL; ntp = ntp->next) {
				to.tsp_type = TSP_LOOP;
				to.tsp_vers = TSPVERSION;
				to.tsp_seq = sequence++;
				to.tsp_hopcnt = MAX_HOPCNT;
				(void)strcpy(to.tsp_name, hostname);
				bytenetorder(&to);
				if (sendto(sock, (char *)&to,
					   sizeof(struct tsp), 0,
					   (struct sockaddr*)&ntp->dest_addr,
					   sizeof(ntp->dest_addr)) < 0) {
				   trace_sendto_err(ntp->dest_addr.sin_addr);
				}
			}
		}


	} else {
		switch (msg->tsp_type) {

		case TSP_MASTERREQ:
			break;

		case TSP_SLAVEUP:
			newslave(msg);
			break;

		case TSP_SETDATE:
			/*
			 * XXX check to see it is from ourself
			 */
#ifdef sgi
			(void)cftime(newdate, "%D %T", &msg->tsp_time.tv_sec);
#else
			(void)strcpy(newdate, ctime(&msg->tsp_time.tv_sec));
#endif /* sgi */
			if (!good_host_name(msg->tsp_name)) {
				syslog(LOG_NOTICE,
				       "attempted date change by %s to %s",
				       msg->tsp_name, newdate);
				spreadtime();
				break;
			}

			mchgdate(msg);
			(void)gettimeofday(&ntime, 0);
			pollingtime = ntime.tv_sec + SAMPLEINTVL;
			break;

		case TSP_SETDATEREQ:
			if (!fromnet || fromnet->status != MASTER)
				break;
#ifdef sgi
			(void)cftime(newdate, "%D %T", &msg->tsp_time.tv_sec);
#else
			(void)strcpy(newdate, ctime(&msg->tsp_time.tv_sec));
#endif /* sgi */
			htp = findhost(msg->tsp_name);
			if (htp == 0) {
				syslog(LOG_ERR,
				       "attempted SET DATEREQ by uncontrolled %s to %s",
				       msg->tsp_name, newdate);
				break;
			}
			if (htp->seq == msg->tsp_seq)
				break;
			htp->seq = msg->tsp_seq;
			if (!htp->good) {
				syslog(LOG_NOTICE,
				"attempted SET DATEREQ by untrusted %s to %s",
				       msg->tsp_name, newdate);
				spreadtime();
				break;
			}

			mchgdate(msg);
			(void)gettimeofday(&ntime, 0);
			pollingtime = ntime.tv_sec + SAMPLEINTVL;
			break;

		case TSP_MSITE:
			xmit(TSP_ACK, msg->tsp_seq, &from);
			break;

		case TSP_MSITEREQ:
			break;

		case TSP_TRACEON:
			traceon();
			break;

		case TSP_TRACEOFF:
			traceoff("Tracing ended at %s\n");
			break;

		case TSP_ELECTION:
			if (!fromnet)
				break;
			if (fromnet->status == MASTER) {
				pollingtime = 0;
				(void)addmach(msg->tsp_name, &from,fromnet);
			}
			taddr = from;
			(void)strcpy(tname, msg->tsp_name);
			to.tsp_type = TSP_QUIT;
			(void)strcpy(to.tsp_name, hostname);
			answer = acksend(&to, &taddr, tname,
					 TSP_ACK, 0, 1);
			if (answer == NULL) {
				syslog(LOG_ERR, "election error by %s",
				       tname);
			}
			break;

		case TSP_CONFLICT:
			/*
			 * After a network partition, there can be
			 * more than one master: the first slave to
			 * come up will notify here the situation.
			 */
			if (!fromnet || fromnet->status != MASTER)
				break;
			(void)strcpy(to.tsp_name, hostname);

			/* The other master often gets into the same state,
			 * with boring results if we stay at it forever.
			 */
			ntp = fromnet;	/* (acksend() can leave fromnet=0 */
			for (i = 0; i < 3; i++) {
				to.tsp_type = TSP_RESOLVE;
				(void)strcpy(to.tsp_name, hostname);
				answer = acksend(&to, &ntp->dest_addr,
						 ANYADDR, TSP_MASTERACK,
						 ntp, 0);
				if (!answer)
					break;
				htp = addmach(answer->tsp_name,&from,ntp);
				to.tsp_type = TSP_QUIT;
				msg = acksend(&to, &htp->addr, htp->name,
					      TSP_ACK, 0, htp->noanswer);
				if (msg == NULL) {
					syslog(LOG_ERR,
				    "no response from %s to CONFLICT-QUIT",
					       htp->name);
				}
			}
			masterup(ntp);
			pollingtime = 0;
			break;

		case TSP_RESOLVE:
			if (!fromnet || fromnet->status != MASTER)
				break;
			/*
			 * do not want to call synch() while waiting
			 * to be killed!
			 */
			(void)gettimeofday(&ntime, (struct timezone *)0);
			pollingtime = ntime.tv_sec + SAMPLEINTVL;
			break;

		case TSP_QUIT:
			doquit(msg);		/* become a slave */
			break;

		case TSP_LOOP:
			if (!fromnet || fromnet->status != MASTER
			    || !strcmp(msg->tsp_name, hostname))
				break;
			/*
			 * We should not have received this from a net
			 * we are master on.  There must be two masters.
			 */
			htp = addmach(msg->tsp_name, &from,fromnet);
			to.tsp_type = TSP_QUIT;
			(void)strcpy(to.tsp_name, hostname);
			answer = acksend(&to, &htp->addr, htp->name,
					 TSP_ACK, 0, 1);
			if (!answer) {
				syslog(LOG_WARNING,
				"loop breakage: no reply from %s=%s to QUIT",
				    htp->name, inet_ntoa(htp->addr.sin_addr));
				(void)remmach(htp);
			}

		case TSP_TEST:
			if (trace) {
				fprintf(fd,
		"\tnets = %d, masters = %d, slaves = %d, ignored = %d\n",
		nnets, nmasternets, nslavenets, nignorednets);
				setstatus();
			}
			pollingtime = 0;
			polls = POLLRATE-1;
			break;

		default:
			if (trace) {
				fprintf(fd, "garbage message: ");
				print(msg, &from);
			}
			break;
		}
	}
	goto loop;
}


/*
 * change the system date on the master
 */
static void
mchgdate(msg)
	struct tsp *msg;
{
	char tname[MAXHOSTNAMELEN];
	char olddate[32];
	struct timeval otime, ntime;

	(void)strcpy(tname, msg->tsp_name);

	xmit(TSP_DATEACK, msg->tsp_seq, &from);

	(void)strcpy(olddate, date());

	/* adjust time for residence on the queue */
	(void)gettimeofday(&otime, 0);
	adj_msg_time(msg,&otime);

	timevalsub(&ntime, &msg->tsp_time, &otime);
	if (ntime.tv_sec < MAXADJ && ntime.tv_sec > -MAXADJ) {
		/*
		 * do not change the clock if we can adjust it
		 */
		dictate = 3;
		synch(tvtomsround(ntime));
	} else {
#ifdef sgi
		if (0 > settimeofday(&msg->tsp_time, 0)) {
			syslog(LOG_ERR, "settimeofday(): %m");
		}
		logwtmp(&otime, &msg->tsp_time);
#else
		logwtmp("|", "date", "");
		(void)settimeofday(&msg->tsp_time, 0);
		logwtmp("}", "date", "");
#endif /* sgi */
		spreadtime();
	}

	syslog(LOG_NOTICE, "date changed by %s from %s",
	       tname, olddate);
}


/*
 * synchronize all of the slaves
 */
void
synch(mydelta)
	long mydelta;
{
	struct hosttbl *htp;
	int measure_status;
	struct timeval check, stop, wait;
#ifdef sgi
	int pri;
#endif /* sgi */

	if (slvcount > 0) {
		if (trace)
			fprintf(fd, "measurements starting at %s\n", date());
		(void)gettimeofday(&check, 0);
#ifdef sgi
		/* run fast to get good time */
		pri = schedctl(NDPRI,0,NDPHIMIN);
		if (pri < 0)
			syslog(LOG_ERR, "schedctl(): %m");
#endif /* sgi */
		for (htp = self.l_fwd; htp != &self; htp = htp->l_fwd) {
			if (htp->noanswer != 0) {
				measure_status = measure(500, 100,
							 htp->name,
							 &htp->addr,0);
			} else {
				measure_status = measure(3000, 100,
							 htp->name,
							 &htp->addr,0);
			}
			if (measure_status != GOOD) {
				/* The slave did not respond.  We have
				 * just wasted lots of time on it.
				 */
				htp->delta = HOSTDOWN;
				if (++htp->noanswer >= LOSTHOST) {
					if (trace) {
						fprintf(fd,
					"purging %s for not answering ICMP\n",
							htp->name);
						(void)fflush(fd);
					}
					htp = remmach(htp);
				}
			} else {
				htp->delta = measure_delta;
			}
			(void)gettimeofday(&stop, 0);