slave.c

早期freebsd实现

#else
			(void)strcpy(newdate, ctime(&msg->tsp_time.tv_sec));
#endif /* sgi */
			schgdate(msg, newdate);
			break;

		case TSP_SETDATEREQ:
			if (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 (0 == htp) {
				syslog(LOG_WARNING,
				       "DATEREQ from uncontrolled machine");
				break;
			}
			if (!htp->good) {
				syslog(LOG_WARNING,
				"attempted date change by untrusted %s to %s",
				       htp->name, newdate);
				spreadtime();
				break;
			}
			schgdate(msg, newdate);
			break;

		case TSP_TRACEON:
			traceon();
			break;

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

		case TSP_SLAVEUP:
			newslave(msg);
			break;

		case TSP_ELECTION:
			if (fromnet->status == SLAVE) {
				(void)gettimeofday(&ntime, 0);
				electiontime = ntime.tv_sec + delay2;
				fastelection = ntime.tv_sec + FASTTOUT;
				seq = 0;
				if (!good_host_name(msg->tsp_name)) {
					syslog(LOG_NOTICE,
					       "suppress election of %s",
					       msg->tsp_name);
					to.tsp_type = TSP_QUIT;
					electiontime = fastelection;
				} else if (cadr.s_addr != from.sin_addr.s_addr
					   && ntime.tv_sec < refusetime) {
/* if the candidate has to repeat itself, the old code would refuse it
 * the second time.  That would prevent elections.
 */
					to.tsp_type = TSP_REFUSE;
				} else {
					cadr.s_addr = from.sin_addr.s_addr;
					to.tsp_type = TSP_ACCEPT;
					refusetime = ntime.tv_sec + 30;
				}
				taddr = from;
				(void)strcpy(tname, msg->tsp_name);
				(void)strcpy(to.tsp_name, hostname);
				answerdelay();
				if (!acksend(&to, &taddr, tname,
					     TSP_ACK, 0, 0))
					syslog(LOG_WARNING,
					     "no answer from candidate %s\n",
					       tname);

			} else {	/* fromnet->status == MASTER */
				htp = addmach(msg->tsp_name, &from,fromnet);
				to.tsp_type = TSP_QUIT;
				(void)strcpy(to.tsp_name, hostname);
				if (!acksend(&to, &htp->addr, htp->name,
					     TSP_ACK, 0, htp->noanswer)) {
					syslog(LOG_ERR,
					  "no reply from %s to ELECTION-QUIT",
					       htp->name);
					(void)remmach(htp);
				}
			}
			break;

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

			/* The other master often gets into the same state,
			 * with boring results.
			 */
			ntp = fromnet;	/* (acksend() can leave fromnet=0 */
			for (tries = 0; tries < 3; tries++) {
				to.tsp_type = TSP_RESOLVE;
				answer = acksend(&to, &ntp->dest_addr,
						 ANYADDR, TSP_MASTERACK,
						 ntp, 0);
				if (answer == NULL)
					break;
				htp = addmach(answer->tsp_name,&from,ntp);
				to.tsp_type = TSP_QUIT;
				answer = acksend(&to, &htp->addr, htp->name,
						 TSP_ACK, 0, htp->noanswer);
				if (!answer) {
					syslog(LOG_WARNING,
				  "conflict error: no reply from %s to QUIT",
						htp->name);
					(void)remmach(htp);
				}
			}
			masterup(ntp);
			break;

		case TSP_MSITE:
			if (!slavenet)
				break;
			taddr = from;
			to.tsp_type = TSP_MSITEREQ;
			to.tsp_vers = TSPVERSION;
			to.tsp_seq = 0;
			(void)strcpy(to.tsp_name, hostname);
			answer = acksend(&to, &slavenet->dest_addr,
					 ANYADDR, TSP_ACK,
					 slavenet, 0);
			if (answer != NULL
			    && good_host_name(answer->tsp_name)) {
				setmaster(answer);
				to.tsp_type = TSP_ACK;
				(void)strcpy(to.tsp_name, answer->tsp_name);
				bytenetorder(&to);
				if (sendto(sock, (char *)&to,
					   sizeof(struct tsp), 0,
					   (struct sockaddr*)&taddr, sizeof(taddr)) < 0) {
					trace_sendto_err(taddr.sin_addr);
				}
			}
			break;

		case TSP_MSITEREQ:
			break;

		case TSP_ACCEPT:
		case TSP_REFUSE:
		case TSP_RESOLVE:
			break;

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

		case TSP_TEST:
			electiontime = 0;
			break;

		case TSP_LOOP:
			/* looking for loops of masters */
			if (!(status & MASTER))
				break;
			if (fromnet->status == SLAVE) {
			    if (!strcmp(msg->tsp_name, hostname)) {
				/*
				 * Someone forwarded our message back to
				 * us.  There must be a loop.  Tell the
				 * master of this network to quit.
				 *
				 * The other master often gets into
				 * the same state, with boring results.
				 */
				ntp = fromnet;
				for (tries = 0; tries < 3; tries++) {
				    to.tsp_type = TSP_RESOLVE;
				    answer = acksend(&to, &ntp->dest_addr,
						     ANYADDR, TSP_MASTERACK,
						     ntp,0);
				    if (answer == NULL)
					break;
				    taddr = from;
				    (void)strcpy(tname, answer->tsp_name);
				    to.tsp_type = TSP_QUIT;
				    (void)strcpy(to.tsp_name, hostname);
				    if (!acksend(&to, &taddr, tname,
						 TSP_ACK, 0, 1)) {
					syslog(LOG_ERR,
					"no reply from %s to slave LOOP-QUIT",
						 tname);
				    } else {
					electiontime = 0;
				    }
				}
				(void)gettimeofday(&ntime, 0);
				looptime = ntime.tv_sec + FASTTOUT;
			    } else {
				if (msg->tsp_hopcnt-- < 1)
				    break;
				bytenetorder(msg);
				for (ntp = nettab; ntp != 0; ntp = ntp->next) {
				    if (ntp->status == MASTER
					&& 0 > sendto(sock, (char *)msg,
						      sizeof(struct tsp), 0,
					      (struct sockaddr*)&ntp->dest_addr,
						      sizeof(ntp->dest_addr)))
				    trace_sendto_err(ntp->dest_addr.sin_addr);
				}
			    }
			} else {	/* fromnet->status == MASTER */
			    /*
			     * We should not have received this from a net
			     * we are master on.  There must be two masters,
			     * unless the packet was really from us.
			     */
			    if (from.sin_addr.s_addr
				== fromnet->my_addr.s_addr) {
				if (trace)
				    fprintf(fd,"discarding forwarded LOOP\n");
				break;
			    }

			    /*
			     * The other master often gets into the same
			     * state, with boring results.
			     */
			    ntp = fromnet;
			    for (tries = 0; tries < 3; tries++) {
				to.tsp_type = TSP_RESOLVE;
				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;
				(void)strcpy(to.tsp_name, hostname);
				if (!acksend(&to,&htp->addr,htp->name,
					     TSP_ACK, 0, htp->noanswer)) {
					syslog(LOG_ERR,
				    "no reply from %s to master LOOP-QUIT",
					       htp->name);
					(void)remmach(htp);
				}
			    }
			    (void)gettimeofday(&ntime, 0);
			    looptime = ntime.tv_sec + FASTTOUT;
			}
			break;
		default:
			if (trace) {
				fprintf(fd, "garbage message: ");
				print(msg, &from);
			}
			break;
		}
	}
	goto loop;
}


/*
 * tell the world who our master is
 */
static void
setmaster(msg)
	struct tsp *msg;
{
	if (slavenet
	    && (slavenet != old_slavenet
		|| strcmp(msg->tsp_name, master_name)
		|| old_status != status)) {
		(void)strcpy(master_name, msg->tsp_name);
		old_slavenet = slavenet;
		old_status = status;

		if (status & MASTER) {
			syslog(LOG_NOTICE, "submaster to %s", master_name);
			if (trace)
				fprintf(fd, "submaster to %s\n", master_name);

		} else {
			syslog(LOG_NOTICE, "slave to %s", master_name);
			if (trace)
				fprintf(fd, "slave to %s\n", master_name);
		}
	}
}



/*
 * handle date change request on a slave
 */
static void
schgdate(msg, newdate)
	struct tsp *msg;
	char *newdate;
{
	struct tsp to;
	u_short seq;
	struct sockaddr_in taddr;
	struct timeval otime;

	if (!slavenet)
		return;			/* no where to forward */

	taddr = from;
	seq = msg->tsp_seq;

	syslog(LOG_INFO,
	       "forwarding date change by %s to %s",
	       msg->tsp_name, newdate);

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

	to.tsp_type = TSP_SETDATEREQ;
	to.tsp_time = msg->tsp_time;
	(void)strcpy(to.tsp_name, hostname);
	if (!acksend(&to, &slavenet->dest_addr,
		     ANYADDR, TSP_DATEACK,
		     slavenet, 0))
		return;			/* no answer */

	xmit(TSP_DATEACK, seq, &taddr);
}


/*
 * Used before answering a broadcast message to avoid network
 * contention and likely collisions.
 */
static void
answerdelay()
{
#ifdef sgi
	sginap(delay1);
#else
	struct timeval timeout;

	timeout.tv_sec = 0;
	timeout.tv_usec = delay1;

	(void)select(0, (fd_set *)NULL, (fd_set *)NULL, (fd_set *)NULL,
	    &timeout);
	return;
#endif /* sgi */
}