ntptimeset.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

#  ifndef	LOG_NTP
#	define	LOG_NTP LOG_DAEMON
#  endif
		openlog("ntptimeset", LOG_PID | LOG_NDELAY, LOG_NTP);
		if (debug)
			setlogmask(LOG_UPTO(LOG_DEBUG));
		else
			setlogmask(LOG_UPTO(LOG_INFO));
# endif /* LOG_DAEMON */
#endif	/* SYS_WINNT */
	}

	if (debug || verbose)
		msyslog(LOG_INFO, "%s", Version);

	if (horrible)
		msyslog(LOG_INFO, "Dropping %d out of %d packets",
			horrible,horrible+HORRIBLEOK);
	/*
	 * Add servers we are going to be polling
	 */
	loadservers(cfgpath);

	if (sys_numservers < min_servers) {
		msyslog(LOG_ERR, "Found %d servers, require %d servers",
			sys_numservers,min_servers);
		exit(2);
	}

	/*
	 * determine when we will end at least
 	 */
	finish_time = max_period * TIMER_HZ;
	half_time = finish_time >> 1;

	/*
	 * Initialize the time of day routines and the I/O subsystem
	 */
	if (sys_authenticate) {
		init_auth();
#ifdef SYS_WINNT
		if (!key_file) key_file = KEYFILE;
		if (!ExpandEnvironmentStrings(key_file, key_file_storage, MAX_PATH))
		{
			msyslog(LOG_ERR, "ExpandEnvironmentStrings(%s) failed: %m\n",
				key_file);
		} else {
			key_file = key_file_storage;
		}
#endif /* SYS_WINNT */

		if (!authreadkeys(key_file)) {
			msyslog(LOG_ERR, "no key file, exiting");
			exit(1);
		}
		if (!authistrusted(sys_authkey)) {
			char buf[10];

			(void) sprintf(buf, "%lu", (unsigned long)sys_authkey);
			msyslog(LOG_ERR, "authentication key %s unknown", buf);
			exit(1);
		}
	}
	init_io();
	init_alarm();

	/*
	 * Set the priority.
	 */
#ifdef SYS_VXWORKS
	taskPrioritySet( taskIdSelf(), NTPDATE_PRIO);
#endif
#if defined(HAVE_ATT_NICE)
	nice (NTPDATE_PRIO);
#endif
#if defined(HAVE_BSD_NICE)
	(void) setpriority(PRIO_PROCESS, 0, NTPDATE_PRIO);
#endif
#ifdef SYS_WINNT
	process_handle = GetCurrentProcess();
	if (!SetPriorityClass(process_handle, (DWORD) REALTIME_PRIORITY_CLASS)) {
		msyslog(LOG_ERR, "SetPriorityClass failed: %m");
	}
#endif /* SYS_WINNT */

	initializing = 0;

	/*
	 * Use select() on all on all input fd's for unlimited
	 * time.  select() will terminate on SIGALARM or on the
	 * reception of input.	Using select() means we can't do
	 * robust signal handling and we get a potential race
	 * between checking for alarms and doing the select().
	 * Mostly harmless, I think.
	 * Keep going until we have enough information, or time is up.
	 */
	/* On VMS, I suspect that select() can't be interrupted
	 * by a "signal" either, so I take the easy way out and
	 * have select() time out after one second.
	 * System clock updates really aren't time-critical,
	 * and - lacking a hardware reference clock - I have
	 * yet to learn about anything else that is.
	 */
	was_alarmed = 0;
	rbuflist = (struct recvbuf *)0;
	while (finish_time > current_time) {
#if !defined(HAVE_SIGNALED_IO) 
		fd_set rdfdes;
		int nfound;
#elif defined(HAVE_SIGNALED_IO)
		block_io_and_alarm();
#endif

		rbuflist = getrecvbufs();	/* get received buffers */
		if (printmsg) {
			printmsg = 0;
			analysis(0);
		}
		if (alarm_flag) {		/* alarmed? */
			was_alarmed = 1;
			alarm_flag = 0;
		}

		if (!was_alarmed && rbuflist == (struct recvbuf *)0) {
			/*
			 * Nothing to do.  Wait for something.
			 */
#ifndef HAVE_SIGNALED_IO
			rdfdes = fdmask;
# if defined(VMS) || defined(SYS_VXWORKS)
			/* make select() wake up after one second */
			{
				struct timeval t1;

				t1.tv_sec = 1; t1.tv_usec = 0;
				nfound = select(fd+1, &rdfdes, (fd_set *)0,
						(fd_set *)0, &t1);
			}
# else
			nfound = select(fd+1, &rdfdes, (fd_set *)0,
					(fd_set *)0, (struct timeval *)0);
# endif /* VMS */
			if (nfound > 0) {
				l_fp ts;
				get_systime(&ts);
				(void)input_handler(&ts);
			}
			else if (nfound == -1 && errno != EINTR)
				msyslog(LOG_ERR, "select() error: %m");
			else if (debug) {
# if !defined SYS_VXWORKS && !defined SYS_CYGWIN32 /* to unclutter log */
				msyslog(LOG_DEBUG, "select(): nfound=%d, error: %m", nfound);
# endif
			}
#else /* HAVE_SIGNALED_IO */
                        
			wait_for_signal();
#endif /* HAVE_SIGNALED_IO */
			if (alarm_flag) 	/* alarmed? */
			{
				was_alarmed = 1;
				alarm_flag = 0;
			}
			rbuflist = getrecvbufs();  /* get received buffers */
		}
#ifdef HAVE_SIGNALED_IO
		unblock_io_and_alarm();
#endif /* HAVE_SIGNALED_IO */

		/*
		 * Out here, signals are unblocked.  Call timer routine
		 * to process expiry.
		 */
		if (was_alarmed)
		{
			timer();
			was_alarmed = 0;
		}

		/*
		 * Call the data procedure to handle each received
		 * packet.
		 */
		while (rbuflist != (struct recvbuf *)0)
		{
			rbuf = rbuflist;
			rbuflist = rbuf->next;
			receive(rbuf);
			freerecvbuf(rbuf);
		}
#if defined DEBUG && defined SYS_WINNT
		if (debug > 4)
		    printf("getrecvbufs: %ld handler interrupts, %ld frames\n",
			   handler_calls, handler_pkts);
#endif

		/*
		 * Do we have enough information to stop now?
		 */
		if (have_enough())
			break;	/* time to end */

		/*
		 * Go around again
		 */
	}

	/*
	 * adjust the clock and exit accordingly
	 */
	set_local_clock();

	/*
	 * if we get here then we are in trouble
	 */
	return(1);
}


/*
 * analysis - print a message indicating what is happening with time service
 *	      must mimic have_enough() procedure.
 */
static void
analysis(
	int final
	)
{
	if (contacted < sys_numservers) {
		printf("%d servers of %d have been probed with %d packets\n",
		       contacted,sys_numservers,MINTRANSMITS);
		return;
	}
	if (!responding) {
		printf("No response from any of %d servers, network problem?\n",
		       sys_numservers);
		return;
	}
	else if (responding < min_servers) {
		printf("%d servers out of %d responding, need at least %d.\n",
		       responding, sys_numservers, min_servers);
		return;
	}
	if (!validcount) {
		printf("%d servers responding but none have valid time\n",
		       responding);
		return;
	}
	else if (validcount < min_valid) {
		printf("%d servers responding, %d are valid, need %d valid\n",
		       responding,validcount,min_valid);
		return;
	}
	if (!final && valid_n_low != validcount) {
		printf("%d valid servers but only %d have low dispersion\n",
		       validcount,valid_n_low);
		return;
	}
}


/* have_enough - see if we have enough information to terminate probing
 */
static int
have_enough(void)
{
	/* have we contacted all servers yet? */
	if (contacted < sys_numservers)
		return 0;	/* no...try some more */

	/* have we got at least minimum servers responding? */
	if (responding < min_servers)
		return 0;	/* no...try some more */

	/* count the clocks */
	(void) clock_count();

	/* have we got at least minimum valid clocks? */
	if (validcount <= 0 || validcount < min_valid)
		return 0;	/* no...try some more */

	/* do we have all valid servers with low dispersion */
	if (!secondhalf && valid_n_low != validcount)
		return 0;

	/* if we get into the secondhalf then we ignore dispersion */

	/* all conditions have been met...end */
	return 1;
}


/*
 * transmit - transmit a packet to the given server, or mark it completed.
 *	      This is called by the timeout routine and by the receive
 *	      procedure.
 */
static void
transmit(
	register struct server *server
	)
{
	struct pkt xpkt;
	int timeout;

	if (debug > 2)
		printf("transmit(%s)\n", ntoa(&server->srcadr));

	if ((server->reach & 01) == 0) {
		l_fp ts;
		/*
		 * Last message to this server timed out.  Shift
		 * zeros into the filter.
		 */
		L_CLR(&ts);
		clock_filter(server, 0, &ts);
	}

	/*
	 * shift reachable register over
	 */
	server->reach <<= 1;

	/*
	 * If we're here, send another message to the server.  Fill in
	 * the packet and let 'er rip.
	 */
	xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC,
		server->version, MODE_CLIENT);
	xpkt.stratum = STRATUM_TO_PKT(STRATUM_UNSPEC);
	xpkt.ppoll = NTP_MINPOLL;
	xpkt.precision = NTPDATE_PRECISION;
	xpkt.rootdelay = htonl(NTPDATE_DISTANCE);
	xpkt.rootdispersion = htonl(NTPDATE_DISP);
	xpkt.refid = htonl(NTPDATE_REFID);
	L_CLR(&xpkt.reftime);
	L_CLR(&xpkt.org);
	L_CLR(&xpkt.rec);

	/*
	 * Determine whether to authenticate or not.  If so,
	 * fill in the extended part of the packet and do it.
	 * If not, just timestamp it and send it away.
	 */
	if (sys_authenticate) {
		int len;

		xpkt.exten[0] = htonl(sys_authkey);
		get_systime(&server->xmt);
		L_ADDUF(&server->xmt, sys_authdelay);
		HTONL_FP(&server->xmt, &xpkt.xmt);
		len = authencrypt(sys_authkey, (u_int32 *)&xpkt, LEN_PKT_NOMAC);
		if (sendpkt(&(server->srcadr), &xpkt, (int)(LEN_PKT_NOMAC + len))) {
			if (debug > 1)
				printf("failed transmit auth to %s\n",
				    ntoa(&(server->srcadr)));
			return;
		}

		if (debug > 1)
			printf("transmit auth to %s\n",
			    ntoa(&(server->srcadr)));
	} else {
		get_systime(&(server->xmt));
		HTONL_FP(&server->xmt, &xpkt.xmt);
		if (sendpkt(&(server->srcadr), &xpkt, LEN_PKT_NOMAC)) {
			if (debug > 1)
				printf("failed transmit to %s\n", 
				    ntoa(&(server->srcadr)));
			return;
		}

		if (debug > 1)
			printf("transmit to %s\n", ntoa(&(server->srcadr)));
	}

	/*
	 * count transmits, record contacted count and set transmit time
	 */
	if (++server->xmtcnt == MINTRANSMITS)
	    contacted++;
	server->last_xmit = current_time;

	/*
	 * determine timeout for this packet. The more packets we send
	 * to the host, the slower we get. If the host indicates that
	 * it is not "sane" then we expect even less.
	 */
	if (server->xmtcnt < MINTRANSMITS) {
	    /* we have not sent enough */
	    timeout = TIMER_HZ;		/* 1 second probe */
	}
	else if (server->rcvcnt <= 0) {
	    /* we have heard nothing */
	    if (secondhalf)
		timeout = TIMER_HZ<<4;	/* 16 second probe */
	    else
		timeout = TIMER_HZ<<3;	/* 8 second probe */
	}
	else {
	    /* if we have low dispersion then probe infrequently */
	    if (server->dispersion <= DESIREDDISP)
		timeout = TIMER_HZ<<4;	/* 16 second probe */
	    /* if the server is not in sync then let it alone */
	    else if (server->leap == LEAP_NOTINSYNC)
		timeout = TIMER_HZ<<4;	/* 16 second probe */
	    /* if the server looks broken ignore it */
	    else if (server->org.l_ui < server->reftime.l_ui)
		timeout = TIMER_HZ<<5;	/* 32 second probe */
	    else if (secondhalf)
		timeout = TIMER_HZ<<2;	/* 4 second probe */
	    else
		timeout = TIMER_HZ<<1;	/* 2 second probe */
	}

	/*
	 * set next transmit time based on timeout
	 */
	server->event_time = current_time + timeout;
}


/*
 * receive - receive and process an incoming frame
 */
static void
receive(
	struct recvbuf *rbufp
	)
{
	register struct pkt *rpkt;
	register struct server *server;
	register s_fp di;
	l_fp t10, t23;
	l_fp org;
	l_fp rec;
	l_fp ci;
	int has_mac;
	int is_authentic;

	if (debug > 2)
		printf("receive(%s)\n", ntoa(&rbufp->srcadr));
	/*
	 * Check to see if the packet basically looks like something
	 * intended for us.
	 */
	if (rbufp->recv_length == LEN_PKT_NOMAC)
		has_mac = 0;
	else if (rbufp->recv_length >= LEN_PKT_NOMAC)
		has_mac = 1;
	else {
		if (debug > 2)
			printf("receive: packet length %d\n",
			    rbufp->recv_length);
		return;		/* funny length packet */
	}

	rpkt = &(rbufp->recv_pkt);
	if (PKT_VERSION(rpkt->li_vn_mode) < NTP_OLDVERSION ||
	    PKT_VERSION(rpkt->li_vn_mode) > NTP_VERSION) {
		if (debug > 1)
			printf("receive: bad version %d\n",
			       PKT_VERSION(rpkt->li_vn_mode));
		return;
	}

	if ((PKT_MODE(rpkt->li_vn_mode) != MODE_SERVER
	    && PKT_MODE(rpkt->li_vn_mode) != MODE_PASSIVE)
	    || rpkt->stratum >=STRATUM_UNSPEC) {
		if (debug > 1)
			printf("receive: mode %d stratum %d\n",
			    PKT_MODE(rpkt->li_vn_mode), rpkt->stratum);
		return;
	}
	
	/*
	 * So far, so good.  See if this is from a server we know.
	 */
	server = findserver(&(rbufp->srcadr));
	if (server == NULL) {
		if (debug > 1)
			printf("receive: server not found\n");
		return;
	}

	/*
	 * Decode the org timestamp and make sure we're getting a response
	 * to our last request.
	 */
	NTOHL_FP(&rpkt->org, &org);
	if (!L_ISEQU(&org, &server->xmt)) {
		if (debug > 1)
			printf("receive: pkt.org and peer.xmt differ\n");
		return;
	}
	
	/*
	 * Check out the authenticity if we're doing that.
	 */
	if (!sys_authenticate)
		is_authentic = 1;
	else {
		is_authentic = 0;

		if (debug > 3)
			printf("receive: rpkt keyid=%ld sys_authkey=%ld decrypt=%ld\n",
			   (long int)ntohl(rpkt->exten[0]), (long int)sys_authkey,
			   (long int)authdecrypt(sys_authkey, (u_int32 *)rpkt,
				LEN_PKT_NOMAC, (int)(rbufp->recv_length - LEN_PKT_NOMAC)));

		if (has_mac && ntohl(rpkt->exten[0]) == sys_authkey &&
			authdecrypt(sys_authkey, (u_int32 *)rpkt, LEN_PKT_NOMAC,
			(int)(rbufp->recv_length - LEN_PKT_NOMAC)))
			is_authentic = 1;
		if (debug)
			printf("receive: authentication %s\n",
			   is_authentic ? "passed" : "failed");
	}
	server->trust <<= 1;
	if (!is_authentic)
		server->trust |= 1;
	
	/*
	 * Looks good.  Record info from the packet.
	 */
	server->leap = PKT_LEAP(rpkt->li_vn_mode);
	server->stratum = PKT_TO_STRATUM(rpkt->stratum);
	server->precision = rpkt->precision;
	server->rootdelay = ntohl(rpkt->rootdelay);
	server->rootdispersion = ntohl(rpkt->rootdispersion);
	server->refid = rpkt->refid;
	NTOHL_FP(&rpkt->reftime, &server->reftime);
	NTOHL_FP(&rpkt->rec, &rec);
	NTOHL_FP(&rpkt->xmt, &server->org);

	/*
	 * count this guy as responding
	 */
	server->reach |= 1;
	if (server->rcvcnt++ == 0)
		responding++;

	/*