/*
 * ntp_proto.c - NTP version 4 protocol machinery
 *
 * ATTENTION: Get approval from Dave Mills on all changes to this file!
 *
 */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "ntpd.h"
#include "ntp_stdlib.h"
#include "ntp_unixtime.h"
#include "ntp_control.h"
#include "ntp_string.h"

#include <stdio.h>

#if defined(VMS) && defined(VMS_LOCALUNIT)	/*wjm*/
#include "ntp_refclock.h"
#endif

#if defined(__FreeBSD__) && __FreeBSD__ >= 3
#include <sys/sysctl.h>
#endif

/*
 * System variables are declared here. See Section 3.2 of the
 * specification.
 */
u_char	sys_leap;		/* system leap indicator */
u_char	sys_stratum;		/* stratum of system */
s_char	sys_precision;		/* local clock precision */
double	sys_rootdelay;		/* roundtrip delay to primary source */
double	sys_rootdispersion;	/* dispersion to primary source */
u_int32 sys_refid;		/* reference source for local clock */
u_int32 sys_peer_refid;		/* hashed refid of our current peer */
static	double sys_offset;	/* current local clock offset */
l_fp	sys_reftime;		/* time we were last updated */
struct	peer *sys_peer;		/* our current peer */
struct	peer *sys_prefer;	/* our cherished peer */
int	sys_kod;		/* kod credit */
int	sys_kod_rate = 2;	/* max kod packets per second */
u_long	sys_clocktime;		/* last system clock update */
#ifdef OPENSSL
u_long	sys_automax;		/* maximum session key lifetime */
#endif /* OPENSSL */

/*
 * Nonspecified system state variables.
 */
int	sys_bclient;		/* broadcast client enable */
double	sys_bdelay;		/* broadcast client default delay */
int	sys_calldelay;		/* modem callup delay (s) */
int	sys_authenticate;	/* requre authentication for config */
l_fp	sys_authdelay;		/* authentication delay */
static	u_long sys_authdly[2];	/* authentication delay shift reg */
static	u_char leap_consensus;	/* consensus of survivor leap bits */
static	double sys_selerr;	/* select error (squares) */
double	sys_error;		/* system error (s) */
keyid_t	sys_private;		/* private value for session seed */
int	sys_manycastserver;	/* respond to manycast client pkts */
int	peer_ntpdate;		/* active peers in ntpdate mode */
int	sys_survivors;		/* truest of the truechimers */
#ifdef OPENSSL
char	*sys_hostname;		/* gethostname() name */
#endif /* OPENSSL */

/*
 * TOS and multicast mapping stuff
 */
int	sys_floor = 1;		/* cluster stratum floor */
int	sys_ceiling = STRATUM_UNSPEC; /* cluster stratum ceiling*/
int	sys_minsane = 1;	/* minimum candidates */
int	sys_minclock = NTP_MINCLOCK; /* minimum survivors */
int	sys_cohort = 0;		/* cohort switch */
int	sys_ttlmax;		/* max ttl mapping vector index */
u_char	sys_ttl[MAX_TTL];	/* ttl mapping vector */

/*
 * Statistics counters
 */
u_long	sys_stattime;		/* time since reset */
u_long	sys_received;		/* packets received */
u_long	sys_processed;		/* packets processed */
u_long	sys_newversionpkt;	/* current version */
u_long	sys_oldversionpkt;	/* recent version */
u_long	sys_unknownversion;	/* invalid version */
u_long	sys_restricted;		/* access denied */
u_long	sys_badlength;		/* bad length or format */
u_long	sys_badauth;		/* bad authentication */
u_long	sys_limitrejected;	/* rate exceeded */

static	double	root_distance	P((struct peer *));
static	double	clock_combine	P((struct peer **, int));
static	void	peer_xmit	P((struct peer *));
static	void	fast_xmit	P((struct recvbuf *, int, keyid_t, int));
static	void	clock_update	P((void));
int	default_get_precision	P((void));
static	int	peer_unfit	P((struct peer *));

/*
 * transmit - Transmit Procedure. See Section 3.4.2 of the
 *	specification.
 */
void
transmit(
	struct peer *peer	/* peer structure pointer */
	)
{
	int	hpoll;


	/*
	 * The polling state machine. There are two kinds of machines,
	 * those that never expect a reply (broadcast and manycast
	 * server modes) and those that do (all other modes). The dance
	 * is intricate...
	 */
	hpoll = peer->hpoll;
	if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) {

		/*
		 * In broadcast mode the poll interval is fixed
		 * at minpoll.
		 */
		hpoll = peer->minpoll;
	} else if (peer->cast_flags & MDF_ACAST) {

		/*
		 * In manycast mode we start with the minpoll interval
		 * and ttl. However, the actual poll interval is eight
		 * times the nominal poll interval shown here. If fewer
		 * than sys_minclock servers are found, the ttl is
		 * increased by one and we try again. If this continues
		 * to the max ttl, the poll interval is bumped by one
		 * and we try again. If at least sys_minclock servers
		 * are found, the poll interval increases with the
		 * system poll interval to the max and we continue
		 * indefinately. However, about once per day when the
		 * agreement parameters are refreshed, the manycast
		 * clients are reset and we start from the beginning.
		 * This is to catch and clamp the ttl to the lowest
		 * practical value and avoid knocking on spurious doors.
		 */
		if (sys_survivors < sys_minclock && peer->ttl <
		    sys_ttlmax)
			peer->ttl++;
		hpoll = sys_poll;
	} else {

		/*
		 * For associations expecting a reply, the watchdog
		 * counter is bumped by one if the peer has not been
		 * heard since the previous poll. If the counter reaches
		 * the max, the poll interval is doubled and the peer is
		 * demobilized if not configured.
		 */
		peer->unreach++;
		if (peer->unreach >= NTP_UNREACH) {
			hpoll++;
			if (peer->flags & FLAG_CONFIG) {

				/*
				 * If nothing is likely to change in
				 * future, flash the access denied bit
				 * so we won't bother the dude again.
				 */
				if (memcmp((char *)&peer->refid,
				    "DENY", 4) == 0 ||
				    memcmp((char *)&peer->refid,
				    "CRYP", 4) == 0)
					peer->flash |= TEST4;
			} else {
				unpeer(peer);
				return;
			}
		}
		if (peer->burst == 0) {
			u_char oreach;

			oreach = peer->reach;
			peer->reach <<= 1;
			peer->hyst *= HYST_TC;
			if (peer->reach == 0) {

				/*
				 * If this association has become
				 * unreachable, clear it and raise a
				 * trap.
				 */
				if (oreach != 0) {
					report_event(EVNT_UNREACH,
					    peer);
					peer->timereachable =
					    current_time;
					if (peer->flags & FLAG_CONFIG) {
						peer_clear(peer,
						    "INIT");
					} else {
						unpeer(peer);
						return;
					}
				}
				if (peer->flags & FLAG_IBURST)
					peer->burst = NTP_BURST;
			} else {
				/*
				 * Here the peer is reachable. If it has
				 * not been heard for three consecutive
				 * polls, stuff the clock filter. Next,
				 * determine the poll interval. If the
				 * peer is unfit for synchronization,
				 * increase it by one; otherwise, use
				 * the system poll interval. 
				 */
				if (!(peer->reach & 0x07)) {
					clock_filter(peer, 0., 0.,
					    MAXDISPERSE);
					clock_select();
				}
				if (peer_unfit(peer))
					hpoll++;
				else
					hpoll = sys_poll;
				if (peer->flags & FLAG_BURST)
					peer->burst = NTP_BURST;
			}
		} else {

			/*
			 * Source rate control. If we are restrained,
			 * each burst consists of only one packet.
			 */
			if (memcmp((char *)&peer->refid, "RSTR", 4) ==
			    0)
				peer->burst = 0;
			else
				peer->burst--;
			if (peer->burst == 0) {

				/*
				 * If a broadcast client at this point,
				 * the burst has concluded, so we switch
				 * to client mode and purge the keylist,
				 * since no further transmissions will
				 * be made.
				 */
				if (peer->cast_flags & MDF_BCLNT) {
					peer->hmode = MODE_BCLIENT;
#ifdef OPENSSL
					key_expire(peer);
#endif /* OPENSSL */
				}
				poll_update(peer, hpoll);
				if (peer->reach & ((1 << NTP_BURST) - 1))
					clock_select();

				/*
				 * If ntpdate mode and the clock has not
				 * been set and all peers have completed
				 * the burst, we declare a successful
				 * failure.
				 */
				if (mode_ntpdate) {
					peer_ntpdate--;
					if (peer_ntpdate > 0) {
						poll_update(
						    peer, hpoll);
						return;
					}
					msyslog(LOG_NOTICE,
					    "no reply; clock not set");
					exit (0);
				}
				poll_update(peer, hpoll);
				return;
			}
		}
	}
	peer->outdate = current_time;

	/*
	 * Do not transmit if in broadcast cclient mode or access has
	 * been denied. 
	 */
	if (peer->hmode == MODE_BCLIENT || peer->flash & TEST4) {
		poll_update(peer, hpoll);
		return;

	/*
	 * Do not transmit in broadcast mode unless we are synchronized.
	 */
	} else if (peer->hmode == MODE_BROADCAST && sys_peer == NULL) {
		poll_update(peer, hpoll);
		return;
	}
	peer_xmit(peer);
	poll_update(peer, hpoll);
}

/*
 * receive - Receive Procedure.  See section 3.4.3 in the specification.
 */
void
receive(
	struct recvbuf *rbufp
	)
{
	register struct peer *peer;	/* peer structure pointer */
	register struct pkt *pkt;	/* receive packet pointer */
	int	hismode;		/* packet mode */
	int	restrict_mask;		/* restrict bits */
	int	has_mac;		/* length of MAC field */
	int	authlen;		/* offset of MAC field */
	int	is_authentic;		/* cryptosum ok */
	keyid_t	skeyid = 0;		/* key ID */
	struct sockaddr_storage *dstadr_sin; /* active runway */
	struct peer *peer2;		/* aux peer structure pointer */
	l_fp	p_org;			/* originate timestamp */
	l_fp	p_xmt;			/* transmit timestamp */
#ifdef OPENSSL
	keyid_t tkeyid = 0;		/* temporary key ID */
	keyid_t	pkeyid = 0;		/* previous key ID */
	struct autokey *ap;		/* autokey structure pointer */
	int	rval;			/* cookie snatcher */
#endif /* OPENSSL */
	int retcode = AM_NOMATCH;

	/*
	 * Monitor the packet and get restrictions. Note that the packet
	 * length for control and private mode packets must be checked
	 * by the service routines. Note that no statistics counters are
	 * recorded for restrict violations, since these counters are in
	 * the restriction routine. Note the careful distinctions here
	 * between a packet with a format error and a packet that is
	 * simply discarded without prejudice. Some restrictions have to
	 * be handled later in order to generate a kiss-of-death packet.
	 */
	/*
	 * Bogus port check is before anything, since it probably
	 * reveals a clogging attack.
	 */
	sys_received++;
	if (SRCPORT(&rbufp->recv_srcadr) == 0) {
		sys_badlength++;
		return;				/* bogus port */
	}
	ntp_monitor(rbufp);
	restrict_mask = restrictions(&rbufp->recv_srcadr);
#ifdef DEBUG
	if (debug > 1)
		printf("receive: at %ld %s<-%s restrict %03x\n",
		    current_time, stoa(&rbufp->dstadr->sin),
		    stoa(&rbufp->recv_srcadr), restrict_mask);
#endif
	if (restrict_mask & RES_IGNORE) {
		sys_restricted++;
		return;				/* no anything */
	}
	pkt = &rbufp->recv_pkt;
	hismode = (int)PKT_MODE(pkt->li_vn_mode);
	if (hismode == MODE_PRIVATE) {
		if (restrict_mask & RES_NOQUERY) {
			sys_restricted++;
			return;			/* no query private */
		}
		process_private(rbufp, ((restrict_mask &
		    RES_NOMODIFY) == 0));
		return;
	}
	if (hismode == MODE_CONTROL) {
		if (restrict_mask & RES_NOQUERY) {
			sys_restricted++;
			return;			/* no query control */
		}
		process_control(rbufp, restrict_mask);
		return;
	}
	if (restrict_mask & RES_DONTSERVE) {
		sys_restricted++;
		return;				/* no time */
	}
	if (rbufp->recv_length < LEN_PKT_NOMAC) {
		sys_badlength++;
		return;				/* runt packet */
	}
	
	/*
	 * Version check must be after the query packets, since they
	 * intentionally use early version.
	 */
	if (PKT_VERSION(pkt->li_vn_mode) == NTP_VERSION) {
		sys_newversionpkt++;		/* new version */
	} else if (!(restrict_mask & RES_VERSION) &&
	    PKT_VERSION(pkt->li_vn_mode) >= NTP_OLDVERSION) {
		sys_oldversionpkt++;		/* previous version */
	} else {
		sys_unknownversion++;
		return;				/* old version */
	}

	/*
	 * Figure out his mode and validate the packet. This has some
	 * legacy raunch that probably should be removed. In very early
	 * NTP versions mode 0 was equivalent to what later versions
	 * would interpret as client mode.
	 */
	if (hismode == MODE_UNSPEC) {
		if (PKT_VERSION(pkt->li_vn_mode) == NTP_OLDVERSION) {
			hismode = MODE_CLIENT;
		} else {
			sys_badlength++;
			return;                 /* invalid mode */
		}
	}

	/*
	 * Discard broadcast if not enabled as broadcast client. If
	 * Autokey, the wildcard interface cannot be used, so dump
	 * packets gettiing off the bus at that stop as well. This means
	 * that some systems with broken interface code, specifically
	 * Linux, will not work with Autokey.
	 */
	if (hismode == MODE_BROADCAST) {
		if (!sys_bclient || restrict_mask & RES_NOPEER) {
			sys_restricted++;
			return;			/* no client */
		}
#ifdef OPENSSL
		if (crypto_flags && rbufp->dstadr == any_interface) {
			sys_restricted++;
			return;			/* no client */
		}
#endif /* OPENSSL */
	}

	/*
	 * Parse the extension field if present. We figure out whether
	 * an extension field is present by measuring the MAC size. If
	 * the number of words following the packet header is 0 or 1, no
	 * MAC is present and the packet is not authenticated. If 1, the
	 * packet is a reply to a previous request that failed to
	 * authenticate. If 3, the packet is authenticated with DES; if
	 * 5, the packet is authenticated with MD5. If greater than 5,
	 * an extension field is present. If 2 or 4, the packet is a
	 * runt and goes poof! with a brilliant flash.
	 */
	authlen = LEN_PKT_NOMAC;
	has_mac = rbufp->recv_length - authlen;
	while (has_mac > 0) {
		int temp;

		if (has_mac % 4 != 0 || has_mac < 0) {
			sys_badlength++;
			return;			/* bad MAC length */
		}
		if (has_mac == 1 * 4 || has_mac == 3 * 4 || has_mac ==
		    MAX_MAC_LEN) {
			skeyid = ntohl(((u_int32 *)pkt)[authlen / 4]);
			break;

		} else if (has_mac > MAX_MAC_LEN) {
			temp = ntohl(((u_int32 *)pkt)[authlen / 4]) &
			    0xffff;
			if (temp < 4 || temp > NTP_MAXEXTEN || temp % 4
			    != 0) {
				sys_badlength++;
				return;		/* bad MAC length */
			}
			authlen += temp;
			has_mac -= temp;
		} else {
			sys_badlength++;
			return;			/* bad MAC length */
		}
	}
#ifdef OPENSSL
	pkeyid = tkeyid = 0;
#endif /* OPENSSL */

	/*
	 * We have tossed out as many buggy packets as possible early in
	 * the game to reduce the exposure to a clogging attack. Now we
	 * have to burn some cycles to find the association and
	 * authenticate the packet if required. Note that we burn only
	 * MD5 cycles, again to reduce exposure. There may be no
	 * matching association and that's okay.
	 *
	 * More on the autokey mambo. Normally the local interface is
	 * found when the association was mobilized with respect to a
	 * designated remote address. We assume packets arriving from
	 * the remote address arrive via this interface and the local
	 * address used to construct the autokey is the unicast address
	 * of the interface. However, if the sender is a broadcaster,
	 * the interface broadcast address is used instead.
	 * Notwithstanding this technobabble, if the sender is a
	 * multicaster, the broadcast address is null, so we use the
	 * unicast address anyway. Don't ask.
	 */
	peer = findpeer(&rbufp->recv_srcadr, rbufp->dstadr, rbufp->fd,
	    hismode, &retcode);
	is_authentic = 0;
	dstadr_sin = &rbufp->dstadr->sin;
	if (has_mac == 0) {
#ifdef DEBUG
		if (debug)
			printf("receive: at %ld %s<-%s mode %d code %d\n",
			    current_time, stoa(&rbufp->dstadr->sin),
			    stoa(&rbufp->recv_srcadr), hismode,
			    retcode);
#endif
	} else {
#ifdef OPENSSL
		/*
		 * For autokey modes, generate the session key
		 * and install in the key cache. Use the socket
		 * broadcast or unicast address as appropriate.
		 */
		if (skeyid > NTP_MAXKEY) {
		
			/*
			 * More on the autokey dance (AKD). A cookie is
			 * constructed from public and private values.
			 * For broadcast packets, the cookie is public
			 * (zero). For packets that match no
			 * association, the cookie is hashed from the
			 * addresses and private value. For server
			 * packets, the cookie was previously obtained
			 * from the server. For symmetric modes, the
			 * cookie was previously constructed using an
			 * agreement protocol; however, should PKI be
			 * unavailable, we construct a fake agreement as
			 * the EXOR of the peer and host cookies.
			 *
			 * hismode	ephemeral	persistent
			 * =======================================
			 * active	0		cookie#
			 * passive	0%		cookie#
			 * client	sys cookie	0%
			 * server	0%		sys cookie
			 * broadcast	0		0
			 *
			 * # if unsync, 0
			 * % can't happen
			 */
			if (hismode == MODE_BROADCAST) {

				/*
				 * For broadcaster, use the interface
				 * broadcast address when available;
				 * otherwise, use the unicast address
				 * found when the association was
				 * mobilized.
				 */
				pkeyid = 0;
				if (!SOCKNUL(&rbufp->dstadr->bcast))
					dstadr_sin =
					    &rbufp->dstadr->bcast;
			} else if (peer == NULL) {
				pkeyid = session_key(
				    &rbufp->recv_srcadr, dstadr_sin, 0,
				    sys_private, 0);
			} else {
				pkeyid = peer->pcookie;
			}

			/*
			 * The session key includes both the public
			 * values and cookie. In case of an extension
			 * field, the cookie used for authentication
			 * purposes is zero. Note the hash is saved for
			 * use later in the autokey mambo.
			 */
			if (authlen > LEN_PKT_NOMAC && pkeyid != 0) {
				session_key(&rbufp->recv_srcadr,
				    dstadr_sin, skeyid, 0, 2);
				tkeyid = session_key(
				    &rbufp->recv_srcadr, dstadr_sin,
				    skeyid, pkeyid, 0);
			} else {
				tkeyid = session_key(
				    &rbufp->recv_srcadr, dstadr_sin,
				    skeyid, pkeyid, 2);
			}

		}
#endif /* OPENSSL */

		/*
		 * Compute the cryptosum. Note a clogging attack may
		 * succeed in bloating the key cache. If an autokey,
		 * purge it immediately, since we won't be needing it
		 * again. If the packet is authentic, it may mobilize an
		 * association.
		 */
		if (authdecrypt(skeyid, (u_int32 *)pkt, authlen,
		    has_mac)) {
			is_authentic = 1;
			restrict_mask &= ~RES_DONTTRUST;
		} else {
			sys_badauth++;
		}
#ifdef OPENSSL
		if (skeyid > NTP_MAXKEY)
			authtrust(skeyid, 0);
#endif /* OPENSSL */
#ifdef DEBUG
		if (debug)
			printf(
			    "receive: at %ld %s<-%s mode %d code %d keyid %08x len %d mac %d auth %d\n",
			    current_time, stoa(dstadr_sin),
			    stoa(&rbufp->recv_srcadr), hismode, retcode,
			    skeyid, authlen, has_mac,
			    is_authentic);
#endif
	}

	/*
	 * The association matching rules are implemented by a set of
	 * routines and a table in ntp_peer.c. A packet matching an
	 * association is processed by that association. If not and
	 * certain conditions prevail, then an ephemeral association is
	 * mobilized: a broadcast packet mobilizes a broadcast client
	 * aassociation; a manycast server packet mobilizes a manycast
	 * client association; a symmetric active packet mobilizes a
	 * symmetric passive association. And, the adventure
	 * continues...
	 */
	switch (retcode) {
	case AM_FXMIT:

		/*
		 * This is a client mode packet not matching a known
		 * association. If from a manycast client we run a few
		 * sanity checks before deciding to send a unicast
		 * server response. Otherwise, it must be a client
		 * request, so send a server response and go home.
		 */
		if (rbufp->dstadr->flags & INT_MULTICAST) {

			/*
			 * Do not respond to multicast if not configured
			 * as a manycast server.
			 */
			if (!sys_manycastserver)
				return;

			/*
			 * There is no reason to respond to a request if
			 * our time is worse than the manycaster or it
			 * has already synchronized to us.
			 */
			if (sys_peer == NULL ||
			    PKT_TO_STRATUM(pkt->stratum) <
			    sys_stratum || (sys_cohort &&
			    PKT_TO_STRATUM(pkt->stratum) ==
			    sys_stratum) ||
			    rbufp->dstadr->addr_refid == pkt->refid)
				return;		/* manycast dropped */
		}

		/*
		 * Note that we don't require an authentication check
		 * here, since we can't set the system clock; but, we do
		 * send a crypto-NAK to tell the caller about this.
		 */
		if (has_mac && !is_authentic)
			fast_xmit(rbufp, MODE_SERVER, 0, restrict_mask);
		else
			fast_xmit(rbufp, MODE_SERVER, skeyid,
			    restrict_mask);
		return;

	case AM_MANYCAST:

		/*
		 * This is a server mode packet returned in response to
		 * a client mode packet sent to a multicast group
		 * address. The originate timestamp is a good nonce to
		 * reliably associate the reply with what was sent. If
		 * there is no match, that's curious and could be an
		 * intruder attempting to clog, so we just ignore it.
		 *
		 * First, make sure the packet is authentic and not
		 * restricted. If so and the manycast association is
		 * found, we mobilize a client association and copy
		 * pertinent variables from the manycast association to
		 * the new client association.
		 *
		 * There is an implosion hazard at the manycast client,
		 * since the manycast servers send the server packet
		 * immediately. If the guy is already here, don't fire
		 * up a duplicate.
		 */
		if (restrict_mask & RES_DONTTRUST) {
			sys_restricted++;
			return;			/* no trust */
		}

		if (sys_authenticate && !is_authentic)
			return;			/* bad auth */

		if ((peer2 = findmanycastpeer(rbufp)) == NULL)
			return;			/* no assoc match */

		if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
		    MODE_CLIENT, PKT_VERSION(pkt->li_vn_mode),
		    NTP_MINDPOLL, NTP_MAXDPOLL, FLAG_IBURST, MDF_UCAST |
		    MDF_ACLNT, 0, skeyid)) == NULL)
			return;			/* system error */

		/*
		 * We don't need these, but it warms the billboards.
		 */
		peer->ttl = peer2->ttl;
		break;

	case AM_NEWPASS:

		/*
		 * This is the first packet received from a symmetric
		 * active peer. First, make sure it is authentic and not
		 * restricted. If so, mobilize a passive association.
		 * If authentication fails send a crypto-NAK; otherwise,
		 * kiss the frog.
		 */
		if (restrict_mask & RES_DONTTRUST) {
			sys_restricted++;
			return;			/* no trust */
		}
		if (sys_authenticate && !is_authentic) {
			fast_xmit(rbufp, MODE_PASSIVE, 0,
			    restrict_mask);
			return;			/* bad auth */
		}
		if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
		    MODE_PASSIVE, PKT_VERSION(pkt->li_vn_mode),
		    NTP_MINDPOLL, NTP_MAXDPOLL, 0, MDF_UCAST, 0,
		    skeyid)) == NULL)
			return;			/* system error */

		break;

	case AM_NEWBCL:

		/*
		 * This is the first packet received from a broadcast
		 * server. First, make sure it is authentic and not
		 * restricted and that we are a broadcast client. If so,
		 * mobilize a broadcast client association. We don't
		 * kiss any frogs here.
		 */
		if (restrict_mask & RES_DONTTRUST) {
			sys_restricted++;
			return;			/* no trust */
		}
		if (sys_authenticate && !is_authentic)
			return;			/* bad auth */

		if (!sys_bclient)
			return;			/* not a client */

		if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
		    MODE_CLIENT, PKT_VERSION(pkt->li_vn_mode),
		    NTP_MINDPOLL, NTP_MAXDPOLL, FLAG_MCAST |
		    FLAG_IBURST, MDF_BCLNT, 0, skeyid)) == NULL)
			return;			/* system error */
#ifdef OPENSSL
		/*
		 * Danger looms. If this is autokey, go process the
		 * extension fields. If something goes wrong, abandon
		 * ship and don't trust subsequent packets.
		 */
		if (crypto_flags) {
			if ((rval = crypto_recv(peer, rbufp)) !=
			    XEVNT_OK) {
				struct sockaddr_storage mskadr_sin;

				unpeer(peer);
				sys_restricted++;
				SET_HOSTMASK(&mskadr_sin,
				    rbufp->recv_srcadr.ss_family);
				hack_restrict(RESTRICT_FLAGS,
				    &rbufp->recv_srcadr, &mskadr_sin,
				    0, RES_DONTTRUST | RES_TIMEOUT);
#ifdef DEBUG
				if (debug)
					printf(
					    "packet: bad exten %x\n",
					    rval);
#endif
			}
		}
#endif /* OPENSSL */
		return;

	case AM_POSSBCL:

		/*
		 * This is a broadcast packet received in client mode.
		 * It could happen if the initial client/server volley
		 * is not complete before the next broadcast packet is
		 * received. Be liberal in what we accept.
		 */ 
	case AM_PROCPKT:

		/*
		 * This is a symmetric mode packet received in symmetric
		 * mode, a server packet received in client mode or a
		 * broadcast packet received in broadcast client mode.
		 * If it is restricted, this is very strange because it
		 * is rude to send a packet to a restricted address. If
		 * anyway, flash a restrain kiss and skedaddle to
		 * Seattle. If not authentic, leave a light on and
		 * continue.
		 */
		peer->flash = 0;
		if (restrict_mask & RES_DONTTRUST) {
			sys_restricted++;
			if (peer->flags & FLAG_CONFIG)
				peer_clear(peer, "RSTR");
			else
				unpeer(peer);
			return;			/* no trust */
		}
		if (has_mac && !is_authentic)
			peer->flash |= TEST5;	/* bad auth */
		break;

	default:

		/*
		 * Invalid mode combination. This happens when a passive
		 * mode packet arrives and matches another passive
		 * association or no association at all, or when a
		 * server mode packet arrives and matches a broadcast
		 * client association. This is usually the result of
		 * reconfiguring a client on-fly. If authenticated
		 * passive mode packet, send a crypto-NAK; otherwise,
		 * ignore it.
		 */
		if (has_mac && hismode == MODE_PASSIVE)
			fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask);
#ifdef DEBUG
		if (debug)
			printf("receive: bad protocol %d\n", retcode);
#endif
		return;
	}

	/*
	 * We do a little homework. Note we can get here with an
	 * authentication error. We Need to do this in order to validate
	 * a crypto-NAK later. Note the order of processing; it is very
	 * important to avoid livelocks, deadlocks and lockpicks.
	 */
	peer->timereceived = current_time;
	peer->received++;
	if (peer->flash & TEST5)
		peer->flags &= ~FLAG_AUTHENTIC;
	else
		peer->flags |= FLAG_AUTHENTIC;
	NTOHL_FP(&pkt->org, &p_org);
	NTOHL_FP(&pkt->xmt, &p_xmt);

	/*
	 * If the packet is an old duplicate, we let it through so the
	 * extension fields will be processed.
	 */
	if (L_ISEQU(&peer->org, &p_xmt)) {	/* test 1 */
		peer->flash |= TEST1;		/* dupe */
		/* fall through */

	/*
	 * For broadcast server mode, loopback checking is disabled. An
	 * authentication error probably means the server restarted or
	 * rolled a new private value. If so, dump the association
	 * and wait for the next message.
	 */
	} else if (hismode == MODE_BROADCAST) {
		if (peer->flash & TEST5) {
			unpeer(peer);
			return;
		}
		/* fall through */

	/*
	 * For server and symmetric modes, if the association transmit
	 * timestamp matches the packet originate timestamp, loopback is
	 * confirmed. Note in symmetric modes this also happens when the
	 * first packet from the active peer arrives at the newly
	 * mobilized passive peer.  An authentication error probably
	 * means the server or peer restarted or rolled a new private
	 * value, but could be an intruder trying to stir up trouble.
	 * However, if this is a crypto-NAK, we know it is authentic, so
	 * dump the association and wait for the next message.
	 */
	} else if (L_ISEQU(&peer->xmt, &p_org)) {
		if (peer->flash & TEST5) {
			if (has_mac == 4 && pkt->exten[0] == 0) {
				if (peer->flags & FLAG_CONFIG)
					peer_clear(peer, "AUTH");
				else
					unpeer(peer);
			}
			return;
		}
		/* fall through */

	/*
	 * If the client or passive peer has never transmitted anything,
	 * this is either the first message from a symmetric peer or
	 * possibly a duplicate received before the transmit timeout.
	 * Pass it on.
	 */
	} else if (L_ISZERO(&peer->xmt)) {
		/* fall through */

	/*
	 * Now it gets interesting. We have transmitted at least one
	 * packet. If the packet originate timestamp is nonzero, it
	 * does not match the association transmit timestamp, which is a
	 * loopback error. This error might mean a manycast server has
	 * answered a manycast honk from us and we already have an
	 * association for him, in which case quietly drop the packet
	 * here. It might mean an old duplicate, dropped packet or
	 * intruder replay, in which case we drop it later after
	 * extension field processing, but never let it touch the time
	 * values.
	 */
	} else if (!L_ISZERO(&p_org)) {
		if (peer->cast_flags & MDF_ACLNT)
			return;			/* not a client */

		peer->flash |= TEST2;
		/* fall through */

	/*
	 * The packet originate timestamp is zero, meaning the other guy
	 * either didn't receive the first packet or died and restarted.
	 * If the association originate timestamp is zero, this is the
	 * first packet received, so we pass it on.
	 */
	} else if (L_ISZERO(&peer->org)) {
		/* fall through */

	/*
	 * The other guy has restarted and we are still on the wire. We
	 * should demobilize/clear and get out of Dodge. If this is
	 * symmetric mode, we should also send a crypto-NAK.
	 */
	} else {
		if (hismode == MODE_ACTIVE)
			fast_xmit(rbufp, MODE_PASSIVE, 0,
			    restrict_mask);
		else if (hismode == MODE_PASSIVE)
			fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask);
#if DEBUG
		if (debug)
			printf("receive: dropped %03x\n", peer->flash);
#endif
		if (peer->flags & FLAG_CONFIG)
			peer_clear(peer, "DROP");
		else
			unpeer(peer);
		return;
	}
	if (peer->flash & ~TEST2) {
		return;
	}

#ifdef OPENSSL
	/*
	 * More autokey dance. The rules of the cha-cha are as follows:
	 *
	 * 1. If there is no key or the key is not auto, do nothing.
	 *
	 * 2. If this packet is in response to the one just previously
	 *    sent or from a broadcast server, do the extension fields.
	 *    Otherwise, assume bogosity and bail out.
	 *
	 * 3. If an extension field contains a verified signature, it is
	 *    self-authenticated and we sit the dance.
	 *
	 * 4. If this is a server reply, check only to see that the
	 *    transmitted key ID matches the received key ID.
	 *
	 * 5. Check to see that one or more hashes of the current key ID
	 *    matches the previous key ID or ultimate original key ID
	 *    obtained from the broadcaster or symmetric peer. If no
	 *    match, sit the dance and wait for timeout.
	 */
	if (crypto_flags && (peer->flags & FLAG_SKEY)) {
		peer->flash |= TEST10;
		rval = crypto_recv(peer, rbufp);
		if (rval != XEVNT_OK) {
			/* fall through */

		} else if (hismode == MODE_SERVER) {
			if (skeyid == peer->keyid)
				peer->flash &= ~TEST10;
		} else if (!peer->flash & TEST10) {
			peer->pkeyid = skeyid;
		} else if ((ap = (struct autokey *)peer->recval.ptr) !=
		    NULL) {
			int i;

			for (i = 0; ; i++) {
				if (tkeyid == peer->pkeyid ||
				    tkeyid == ap->key) {
					peer->flash &= ~TEST10;
					peer->pkeyid = skeyid;
					break;
				}
				if (i > ap->seq)
					break;
				tkeyid = session_key(
				    &rbufp->recv_srcadr, dstadr_sin,
				    tkeyid, pkeyid, 0);
			}
		}
		if (!(peer->crypto & CRYPTO_FLAG_PROV)) /* test 11 */
			peer->flash |= TEST11;	/* not proventic */

		/*
		 * If the transmit queue is nonempty, clamp the host
		 * poll interval to the packet poll interval.
		 */
		if (peer->cmmd != 0) {
			peer->ppoll = pkt->ppoll;
			poll_update(peer, 0);
		}

		/*
		 * If the return code from extension field processing is
		 * not okay, we scrub the association and start over.
		 */
		if (rval != XEVNT_OK) {

			/*
			 * If the return code is bad, the crypto machine
			 * may be jammed or an intruder may lurk. First,
			 * we demobilize the association, then see if
			 * the error is recoverable.
			 */
			if (peer->flags & FLAG_CONFIG)
				peer_clear(peer, "CRYP");
			else
				unpeer(peer);
#ifdef DEBUG
			if (debug)
				printf("packet: bad exten %x\n", rval);
#endif
			return;
		}

		/*
		 * If TEST10 is lit, the autokey sequence has broken,
		 * which probably means the server has refreshed its
		 * private value. We reset the poll interval to the
		 & minimum and scrub the association clean.
		 */
		if (peer->flash & TEST10 && peer->crypto &
		    CRYPTO_FLAG_AUTO) {
			poll_update(peer, peer->minpoll);
#ifdef DEBUG
			if (debug)
				printf(
				    "packet: bad auto %03x\n",
				    peer->flash);
#endif
			if (peer->flags & FLAG_CONFIG)
				peer_clear(peer, "AUTO");
			else
				unpeer(peer);
			return;
		}
	}
#endif /* OPENSSL */

	/*
	 * We have survived the gaunt. Forward to the packet routine. If
	 * a symmetric passive association has been mobilized and the
	 * association doesn't deserve to live, it will die in the
	 * transmit routine if not reachable after timeout. However, if
	 * either symmetric mode and the crypto code has something
	 * urgent to say, we expedite the response.
	 */
	process_packet(peer, pkt, &rbufp->recv_time);
}


/*
 * process_packet - Packet Procedure, a la Section 3.4.4 of the
 *	specification. Or almost, at least. If we're in here we have a
 *	reasonable expectation that we will be having a long term
 *	relationship with this host.
 */
void
process_packet(
	register struct peer *peer,
	register struct pkt *pkt,
	l_fp	*recv_ts
	)
{
	l_fp	t34, t21;
	double	p_offset, p_del, p_disp;
	double	dtemp;
	l_fp	p_rec, p_xmt, p_org, p_reftime;
	l_fp	ci;
	u_char	pmode, pleap, pstratum;

	/*
	 * Swap header fields and keep the books. The books amount to
	 * the receive timestamp and poll interval in the header. We
	 * need these even if there are other problems in order to crank
	 * up the state machine.
	 */
	sys_processed++;
	peer->processed++;
	p_del = FPTOD(NTOHS_FP(pkt->rootdelay));
	p_disp = FPTOD(NTOHS_FP(pkt->rootdispersion));
	NTOHL_FP(&pkt->reftime, &p_reftime);
	NTOHL_FP(&pkt->rec, &p_rec);
	NTOHL_FP(&pkt->xmt, &p_xmt);
	pmode = PKT_MODE(pkt->li_vn_mode);
	pleap = PKT_LEAP(pkt->li_vn_mode);
	if (pmode != MODE_BROADCAST)
		NTOHL_FP(&pkt->org, &p_org);
	else
		p_org = peer->rec;
	pstratum = PKT_TO_STRATUM(pkt->stratum);

	/*
	 * Test for unsynchronized server.
	 */
	if (L_ISHIS(&peer->org, &p_xmt))	/* count old packets */
		peer->oldpkt++;
	if (pmode != MODE_BROADCAST && (L_ISZERO(&p_rec) ||
	    L_ISZERO(&p_org)))			/* test 3 */
		peer->flash |= TEST3;		/* unsynch */
	if (L_ISZERO(&p_xmt))			/* test 3 */
		peer->flash |= TEST3;		/* unsynch */

	/*
	 * If any tests fail, the packet is discarded leaving only the
	 * timestamps, which are enough to get the protocol started. The
	 * originate timestamp is copied from the packet transmit
	 * timestamp and the receive timestamp is copied from the
	 * packet receive timestamp. If okay so far, we save the leap,
	 * stratum and refid for billboards.
	 */
	peer->org = p_xmt;
	peer->rec = *recv_ts;
	if (peer->flash) {
#ifdef DEBUG
		if (debug)
			printf("packet: bad data %03x from address: %s\n",
			    peer->flash, stoa(&peer->srcadr));
#endif
		return;
	}
	peer->leap = pleap;
	peer->stratum = pstratum;
	peer->refid = pkt->refid;

	/*
	 * Test for valid peer data (tests 6-8)
	 */
	ci = p_xmt;
	L_SUB(&ci, &p_reftime);
	LFPTOD(&ci, dtemp);
	if (pleap == LEAP_NOTINSYNC ||		/* test 6 */
	    pstratum >= STRATUM_UNSPEC || dtemp < 0)
		peer->flash |= TEST6;		/* bad synch */
	if (!(peer->flags & FLAG_CONFIG) && sys_peer != NULL) { /* test 7 */
		if (pstratum > sys_stratum && pmode != MODE_ACTIVE)
			peer->flash |= TEST7;	/* bad stratum */
	}
	if (p_del < 0 || p_disp < 0 || p_del /	/* test 8 */
	    2 + p_disp >= MAXDISPERSE)
		peer->flash |= TEST8;		/* bad peer values */

	/*
	 * If any tests fail at this point, the packet is discarded.
	 */
	if (peer->flash) {
#ifdef DEBUG
		if (debug)
			printf("packet: bad header %03x\n",
			    peer->flash);
#endif
		return;
	}

	/*
	 * The header is valid. Capture the remaining header values and
	 * mark as reachable.
	 */
	record_raw_stats(&peer->srcadr, &peer->dstadr->sin, &p_org,
	    &p_rec, &p_xmt, &peer->rec);
	peer->pmode = pmode;
	peer->ppoll = pkt->ppoll;
	peer->precision = pkt->precision;
	peer->rootdelay = p_del;
	peer->rootdispersion = p_disp;
	peer->reftime = p_reftime;
	if (!(peer->reach)) {
		report_event(EVNT_REACH, peer);
		peer->timereachable = current_time;
	}
	peer->reach |= 1;
	peer->unreach = 0;
	poll_update(peer, 0);

	/*
	 * If running in a client/server association, calculate the
	 * clock offset c, roundtrip delay d and dispersion e. We use
	 * the equations (reordered from those in the spec). Note that,
	 * in a broadcast association, org has been set to the time of
	 * last reception. Note the computation of dispersion includes
	 * the system precision plus that due to the frequency error
	 * since the originate time.
	 *
	 * Let t1 = p_org, t2 = p_rec, t3 = p_xmt, t4 = peer->rec:
	 */
	t34 = p_xmt;			/* t3 - t4 */
	L_SUB(&t34, &peer->rec);
	t21 = p_rec;			/* t2 - t1 */
	L_SUB(&t21, &p_org);
	ci = peer->rec;			/* t4 - t1 */
	L_SUB(&ci, &p_org);
	LFPTOD(&ci, p_disp);
	p_disp = clock_phi * max(p_disp, LOGTOD(sys_precision));

	/*
	 * If running in a broadcast association, the clock offset is
	 * (t1 - t0) corrected by the one-way delay, but we can't
	 * measure that directly. Therefore, we start up in MODE_CLIENT
	 * mode, set FLAG_MCAST and exchange eight messages to determine
	 * the clock offset. When the last message is sent, we switch to
	 * MODE_BCLIENT mode. The next broadcast message after that
	 * computes the broadcast offset and clears FLAG_MCAST.
	 */
	ci = t34;
	if (pmode == MODE_BROADCAST) {
		if (peer->flags & FLAG_MCAST) {
			LFPTOD(&ci, p_offset);
			peer->estbdelay = peer->offset - p_offset;
			if (peer->hmode == MODE_CLIENT)
				return;

			peer->flags &= ~FLAG_MCAST;
		}
		DTOLFP(peer->estbdelay, &t34);
		L_ADD(&ci, &t34);
		p_del = peer->delay;
	} else {
		L_ADD(&ci, &t21);	/* (t2 - t1) + (t3 - t4) */
		L_RSHIFT(&ci);
		L_SUB(&t21, &t34);	/* (t2 - t1) - (t3 - t4) */
		LFPTOD(&t21, p_del);
	}
	p_del = max(p_del, LOGTOD(sys_precision));
	LFPTOD(&ci, p_offset);
	if ((peer->rootdelay + p_del) / 2. + peer->rootdispersion +
	    p_disp >= MAXDISPERSE)		/* test 9 */
		peer->flash |= TEST9;		/* bad root distance */

	/*
	 * If any flasher bits remain set at this point, abandon ship.
	 * Otherwise, forward to the clock filter.
	 */
	if (peer->flash) {
#ifdef DEBUG
		if (debug)
			printf("packet: bad packet data %03x\n",
			    peer->flash);
#endif
		return;
	}
	clock_filter(peer, p_offset, p_del, p_disp);
	if (peer->burst == 0)
		clock_select();
	record_peer_stats(&peer->srcadr, ctlpeerstatus(peer),
	    peer->offset, peer->delay, peer->disp,
	    SQRT(peer->jitter));
}


/*
 * clock_update - Called at system process update intervals.
 */
static void
clock_update(void)
{
	u_char oleap;
	u_char ostratum;

	/*
	 * Reset/adjust the system clock. Do this only if there is a
	 * system peer and the peer epoch is not older than the last
	 * update.
	 */
	if (sys_peer == NULL)
		return;

	if (sys_peer->epoch <= sys_clocktime)
		return;

	sys_clocktime = sys_peer->epoch;
#ifdef DEBUG
	if (debug)
		printf("clock_update: at %ld assoc %d \n", current_time,
		    peer_associations);
#endif
	oleap = sys_leap;
	ostratum = sys_stratum;
	switch (local_clock(sys_peer, sys_offset)) {

	/*
	 * Clock is too screwed up. Just exit for now.
	 */
	case -1:
		report_event(EVNT_SYSFAULT, NULL);
		exit (-1);
		/*NOTREACHED*/

	/*
	 * Clock was stepped. Flush all time values of all peers.
	 */
	case 1:
		clear_all();
		sys_peer = NULL;
		sys_stratum = STRATUM_UNSPEC;
			memcpy(&sys_refid, "STEP", 4);
		sys_poll = NTP_MINPOLL;
		report_event(EVNT_CLOCKRESET, NULL);
#ifdef OPENSSL
		if (oleap != LEAP_NOTINSYNC)
			expire_all();
#endif /* OPENSSL */
		break;

	/*
	 * Update the system stratum, leap bits, root delay, root
	 * dispersion, reference ID and reference time. We also update
	 * select dispersion and max frequency error. If the leap
	 * changes, we gotta reroll the keys.
	 */
	default:
		sys_stratum = (u_char) (sys_peer->stratum + 1);
		if (sys_stratum == 1 || sys_stratum == STRATUM_UNSPEC)
			sys_refid = sys_peer->refid;
		else
			sys_refid = sys_peer_refid;
		sys_reftime = sys_peer->rec;
		sys_rootdelay = sys_peer->rootdelay + sys_peer->delay;
		sys_leap = leap_consensus;
		if (oleap == LEAP_NOTINSYNC) {
			report_event(EVNT_SYNCCHG, NULL);
#ifdef OPENSSL
			expire_all();
#endif /* OPENSSL */
		}
	}
	if (ostratum != sys_stratum)
		report_event(EVNT_PEERSTCHG, NULL);
}


/*
 * poll_update - update peer poll interval
 */
void
poll_update(
	struct peer *peer,
	int	hpoll
	)
{
#ifdef OPENSSL
	int	oldpoll;
#endif /* OPENSSL */

	/*
	 * A little foxtrot to determine what controls the poll
	 * interval. If the peer is reachable, but the last four polls
	 * have not been answered, use the minimum. If declared
	 * truechimer, use the system poll interval. This allows each
	 * association to ramp up the poll interval for useless sources
	 * and to clamp it to the minimum when first starting up.
	 */
#ifdef OPENSSL
	oldpoll = peer->kpoll;
#endif /* OPENSSL */
	if (hpoll > 0) {
		if (hpoll > peer->maxpoll)
			peer->hpoll = peer->maxpoll;
		else if (hpoll < peer->minpoll)
			peer->hpoll = peer->minpoll;
		else
			peer->hpoll = (u_char)hpoll;
	}

	/*
	 * Bit of adventure here. If during a burst and not a poll, just
	 * slink away. If a poll, figure what the next poll should be.
	 * If a burst is pending and a reference clock or a pending
	 * crypto response, delay for one second. If the first sent in a
	 * burst, delay ten seconds for the modem to come up. For others
	 * in the burst, delay two seconds.
	 *
	 * In case of manycast server, make the poll interval, which is
	 * axtually the manycast beacon interval, eight times the system
	 * poll interval. Normally when the host poll interval settles
	 * up to 1024 s, the beacon interval settles up to 2.3 hours.
	 */
#ifdef OPENSSL
	if (peer->cmmd != NULL && (sys_leap != LEAP_NOTINSYNC ||
	    peer->crypto)) {
		peer->nextdate = current_time + RESP_DELAY;
	} else if (peer->burst > 0) {
#else /* OPENSSL */
	if (peer->burst > 0) {
#endif /* OPENSSL */
		if (hpoll == 0 && peer->nextdate != current_time)
			return;
#ifdef REFCLOCK
		else if (peer->flags & FLAG_REFCLOCK)
			peer->nextdate += RESP_DELAY;
#endif
		else if (peer->flags & (FLAG_IBURST | FLAG_BURST) &&
		    peer->burst == NTP_BURST)
			peer->nextdate += sys_calldelay;
		else
			peer->nextdate += BURST_DELAY;
	} else if (peer->cast_flags & MDF_ACAST) {
		if (sys_survivors >= sys_minclock || peer->ttl >=
		    sys_ttlmax)
			peer->kpoll = (u_char) (peer->hpoll + 3);
		else
			peer->kpoll = peer->hpoll;
		peer->nextdate = peer->outdate + RANDPOLL(peer->kpoll);
	} else {
		peer->kpoll = (u_char) max(min(peer->ppoll,
		    peer->hpoll), peer->minpoll);
		peer->nextdate = peer->outdate + RANDPOLL(peer->kpoll);
	}
	if (peer->nextdate < current_time)
		peer->nextdate = current_time;
#ifdef OPENSSL
	/*
	 * Bit of crass arrogance at this point. If the poll interval
	 * has changed and we have a keylist, the lifetimes in the
	 * keylist are probably bogus. In this case purge the keylist
	 * and regenerate it later.
	 */
	if (peer->kpoll != oldpoll)
		key_expire(peer);
#endif /* OPENSSL */
#ifdef DEBUG
	if (debug > 1)
		printf("poll_update: at %lu %s flags %04x poll %d burst %d last %lu next %lu\n",
		    current_time, ntoa(&peer->srcadr), peer->flags,
		    peer->kpoll, peer->burst, peer->outdate,
		    peer->nextdate);
#endif
}


/*
 * clear - clear peer filter registers.  See Section 3.4.8 of the spec.
 */
void
peer_clear(
	struct peer *peer,		/* peer structure */
	char	*ident			/* tally lights */
	)
{
	u_char	oreach, i;

	/*
	 * If cryptographic credentials have been acquired, toss them to
	 * Valhalla. Note that autokeys are ephemeral, in that they are
	 * tossed immediately upon use. Therefore, the keylist can be
	 * purged anytime without needing to preserve random keys. Note
	 * that, if the peer is purged, the cryptographic variables are
	 * purged, too. This makes it much harder to sneak in some
	 * unauthenticated data in the clock filter.
	 */
	oreach = peer->reach;
#ifdef OPENSSL
	key_expire(peer);
	if (peer->pkey != NULL)
		EVP_PKEY_free(peer->pkey);
	if (peer->ident_pkey != NULL)
		EVP_PKEY_free(peer->ident_pkey);
	if (peer->subject != NULL)
		free(peer->subject);
	if (peer->issuer != NULL)
		free(peer->issuer);
	if (peer->iffval != NULL)
		BN_free(peer->iffval);
	if (peer->grpkey != NULL)
		BN_free(peer->grpkey);
	if (peer->cmmd != NULL)
		free(peer->cmmd);
	value_free(&peer->cookval);
	value_free(&peer->recval);
	value_free(&peer->tai_leap);
	value_free(&peer->encrypt);
	value_free(&peer->sndval);
#endif /* OPENSSL */

	/*
	 * Wipe the association clean and initialize the nonzero values.
	 */
	memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO);
	if (peer == sys_peer)
		sys_peer = NULL;
	peer->estbdelay = sys_bdelay;
	peer->hpoll = peer->kpoll = peer->minpoll;
	peer->ppoll = peer->maxpoll;
	peer->jitter = MAXDISPERSE;
	peer->epoch = current_time;
#ifdef REFCLOCK
	if (!(peer->flags & FLAG_REFCLOCK)) {
		peer->leap = LEAP_NOTINSYNC;
		peer->stratum = STRATUM_UNSPEC;
		memcpy(&peer->refid, ident, 4);
	}
#else
	peer->leap = LEAP_NOTINSYNC;
	peer->stratum = STRATUM_UNSPEC;
	memcpy(&peer->refid, ident, 4);
#endif
	for (i = 0; i < NTP_SHIFT; i++) {
		peer->filter_order[i] = i;
		peer->filter_disp[i] = MAXDISPERSE;
		peer->filter_epoch[i] = current_time;
	}

	/*
	 * If he dies as a broadcast client, he comes back to life as
	 * a broadcast client in client mode in order to recover the
	 * initial autokey values.
	 */
	if (peer->cast_flags & MDF_BCLNT) {
		peer->flags |= FLAG_MCAST;
		peer->hmode = MODE_CLIENT;
	}

	/*
	 * Randomize the first poll to avoid bunching, but only if the
	 * rascal has never been heard. During initialization use the
	 * association count to spread out the polls at one-second
	 * intervals.
	 */
	peer->nextdate = peer->update = peer->outdate = current_time;
	peer->burst = 0;
	if (oreach)
		poll_update(peer, 0);
	else if (initializing)
		peer->nextdate = current_time + peer_associations;
	else
		peer->nextdate = current_time + (u_int)RANDOM %
		    peer_associations;
#ifdef DEBUG
	if (debug)
		printf("peer_clear: at %ld assoc ID %d refid %s\n",
		    current_time, peer->associd, ident);
#endif
}


/*
 * clock_filter - add incoming clock sample to filter register and run
 *		  the filter procedure to find the best sample.
 */
void
clock_filter(
	struct peer *peer,		/* peer structure pointer */
	double	sample_offset,		/* clock offset */
	double	sample_delay,		/* roundtrip delay */
	double	sample_disp		/* dispersion */
	)
{
	double	dst[NTP_SHIFT];		/* distance vector */
	int	ord[NTP_SHIFT];		/* index vector */
	int	i, j, k, m;
	double	dsp, jit, dtemp, etemp;

	/*
	 * Shift the new sample into the register and discard the oldest
	 * one. The new offset and delay come directly from the
	 * timestamp calculations. The dispersion grows from the last
	 * outbound packet or reference clock update to the present time
	 * and increased by the sum of the peer precision and the system
	 * precision. The delay can sometimes swing negative due to
	 * frequency skew, so it is clamped non-negative.
	 */
	dsp = min(LOGTOD(peer->precision) + LOGTOD(sys_precision) +
	    sample_disp, MAXDISPERSE);
	j = peer->filter_nextpt;
	peer->filter_offset[j] = sample_offset;
	peer->filter_delay[j] = max(0, sample_delay);
	peer->filter_disp[j] = dsp;
	j++; j %= NTP_SHIFT;
	peer->filter_nextpt = (u_short) j;

	/*
	 * Update dispersions since the last update and at the same
	 * time initialize the distance and index lists. The distance
	 * list uses a compound metric. If the sample is valid and
	 * younger than the minimum Allan intercept, use delay;
	 * otherwise, use biased dispersion.
	 */
	dtemp = clock_phi * (current_time - peer->update);
	peer->update = current_time;
	for (i = NTP_SHIFT - 1; i >= 0; i--) {
		if (i != 0)
			peer->filter_disp[j] += dtemp;
		if (peer->filter_disp[j] >= MAXDISPERSE) 
			peer->filter_disp[j] = MAXDISPERSE;
		if (peer->filter_disp[j] >= MAXDISPERSE)
			dst[i] = MAXDISPERSE;
		else if (peer->update - peer->filter_epoch[j] >
		    allan_xpt)
			dst[i] = MAXDISTANCE + peer->filter_disp[j];
		else
			dst[i] = peer->filter_delay[j];
		ord[i] = j;
		j++; j %= NTP_SHIFT;
	}
	peer->filter_epoch[j] = current_time;

        /*
	 * Sort the samples in both lists by distance.
	 */
	for (i = 1; i < NTP_SHIFT; i++) {
		for (j = 0; j < i; j++) {
			if (dst[j] > dst[i]) {
				k = ord[j];
				ord[j] = ord[i];
				ord[i] = k;
				etemp = dst[j];
				dst[j] = dst[i];
				dst[i] = etemp;
			}
		}
	}

	/*
	 * Copy the index list to the association structure so ntpq
	 * can see it later. Prune the distance list to samples less
	 * than MAXDISTANCE, but keep at least two valid samples for
	 * jitter calculation.
	 */
	m = 0;
	for (i = 0; i < NTP_SHIFT; i++) {
		peer->filter_order[i] = (u_char) ord[i];
		if (dst[i] >= MAXDISPERSE || (m >= 2 && dst[i] >=
		    MAXDISTANCE))
			continue;
		m++;
	}
	
	/*
	 * Compute the dispersion and jitter squares. The dispersion
	 * is weighted exponentially by NTP_FWEIGHT (0.5) so it is
	 * normalized close to 1.0. The jitter is the mean of the square
	 * differences relative to the lowest delay sample. If no
	 * acceptable samples remain in the shift register, quietly
	 * tiptoe home leaving only the dispersion.
	 */
	jit = 0;
	peer->disp = 0;
	k = ord[0];
	for (i = NTP_SHIFT - 1; i >= 0; i--) {

		j = ord[i];
		peer->disp = NTP_FWEIGHT * (peer->disp +
		    peer->filter_disp[j]);
		if (i < m)
			jit += DIFF(peer->filter_offset[j],
			    peer->filter_offset[k]);
	}

	/*
	 * If no acceptable samples remain in the shift register,
	 * quietly tiptoe home leaving only the dispersion. Otherwise,
	 * save the offset, delay and jitter average. Note the jitter
	 * must not be less than the system precision.
	 */
	if (m == 0)
		return;
	etemp = fabs(peer->offset - peer->filter_offset[k]);
	dtemp = sqrt(peer->jitter);
	peer->offset = peer->filter_offset[k];
	peer->delay = peer->filter_delay[k];
	if (m > 1)
		jit /= m - 1;
	peer->jitter = max(jit, SQUARE(LOGTOD(sys_precision)));

	/*
	 * A new sample is useful only if it is younger than the last
	 * one used, but only if the sucker has been synchronized.
	 */
	if (peer->filter_epoch[k] <= peer->epoch && sys_leap !=
	    LEAP_NOTINSYNC) {
#ifdef DEBUG
		if (debug)
			printf("clock_filter: discard %lu\n",
			    peer->epoch - peer->filter_epoch[k]);
#endif
		return;
	}

	/*
	 * If the difference between the last offset and the current one
	 * exceeds the jitter by CLOCK_SGATE and the interval since the
	 * last update is less than twice the system poll interval,
	 * consider the update a popcorn spike and ignore it.
	 */
	if (m > 1 && etemp > CLOCK_SGATE * dtemp &&
	    (long)(peer->filter_epoch[k] - peer->epoch) < (1 << (sys_poll +
	    1))) {
#ifdef DEBUG
		if (debug)
			printf("clock_filter: popcorn %.6f %.6f\n",
			    etemp, dtemp);
#endif
		return;
	}

	/*
	 * The mitigated sample statistics are saved for later
	 * processing.
	 */
	peer->epoch = peer->filter_epoch[k];
#ifdef DEBUG
	if (debug)
		printf(
		    "clock_filter: n %d off %.6f del %.6f dsp %.6f jit %.6f, age %lu\n",
		    m, peer->offset, peer->delay, peer->disp,
		    SQRT(peer->jitter), peer->update - peer->epoch);
#endif
}


/*
 * clock_select - find the pick-of-the-litter clock
 *
 * LOCKCLOCK: If the local clock is the prefer peer, it will always be
 * enabled, even if declared falseticker, (2) only the prefer peer can
 * be selected as the system peer, (3) if the external source is down,
 * the system leap bits are set to 11 and the stratum set to infinity.
 */
void
clock_select(void)
{
	struct peer *peer;
	int	i, j, k, n;
	int	nlist, nl3;

	double	d, e, f;
	int	allow, sw, osurv;
	double	high, low;
	double	synch[NTP_MAXCLOCK], error[NTP_MAXCLOCK];
	struct peer *osys_peer;
	struct peer *typeacts = NULL;
	struct peer *typelocal = NULL;
	struct peer *typepps = NULL;
	struct peer *typesystem = NULL;

	static int list_alloc = 0;
	static struct endpoint *endpoint = NULL;
	static int *indx = NULL;
	static struct peer **peer_list = NULL;
	static u_int endpoint_size = 0;
	static u_int indx_size = 0;
	static u_int peer_list_size = 0;

	/*
	 * Initialize and create endpoint, index and peer lists big
	 * enough to handle all associations.
	 */
	osys_peer = sys_peer;
	sys_peer = NULL;
	osurv = sys_survivors;
	sys_survivors = 0;
	sys_prefer = NULL;
#ifdef LOCKCLOCK
	sys_leap = LEAP_NOTINSYNC;
	sys_stratum = STRATUM_UNSPEC;
	memcpy(&sys_refid, "DOWN", 4);
#endif /* LOCKCLOCK */
	nlist = 0;
	for (n = 0; n < NTP_HASH_SIZE; n++)
		nlist += peer_hash_count[n];
	if (nlist > list_alloc) {
		if (list_alloc > 0) {
			free(endpoint);
			free(indx);
			free(peer_list);
		}
		while (list_alloc < nlist) {
			list_alloc += 5;
			endpoint_size += 5 * 3 * sizeof(*endpoint);
			indx_size += 5 * 3 * sizeof(*indx);
			peer_list_size += 5 * sizeof(*peer_list);
		}
		endpoint = emalloc(endpoint_size);
		indx = emalloc(indx_size);
		peer_list = emalloc(peer_list_size);
	}

	/*
	 * Initially, we populate the island with all the rifraff peers
	 * that happen to be lying around. Those with seriously
	 * defective clocks are immediately booted off the island. Then,
	 * the falsetickers are culled and put to sea. The truechimers
	 * remaining are subject to repeated rounds where the most
	 * unpopular at each round is kicked off. When the population
	 * has dwindled to sys_minclock, the survivors split a million
	 * bucks and collectively crank the chimes.
	 */
	nlist = nl3 = 0;	/* none yet */
	for (n = 0; n < NTP_HASH_SIZE; n++) {
		for (peer = peer_hash[n]; peer != NULL; peer =
		    peer->next) {
			peer->flags &= ~FLAG_SYSPEER;
			peer->status = CTL_PST_SEL_REJECT;

			/*
			 * Leave the island immediately if the peer is
			 * unfit to synchronize.
			 */
			if (peer_unfit(peer) || root_distance(peer) >=
			    MAXDISTANCE + 2. * clock_phi *
			    ULOGTOD(sys_poll))
				continue;

			/*
			 * Don't allow the local clock or modem drivers
			 * in the kitchen at this point, unless the
			 * prefer peer. Do that later, but only if
			 * nobody else is around. These guys are all
			 * configured, so we never throw them away.
			 */
			if (peer->refclktype == REFCLK_LOCALCLOCK
#if defined(VMS) && defined(VMS_LOCALUNIT)
			/* wjm: VMS_LOCALUNIT taken seriously */
			    && REFCLOCKUNIT(&peer->srcadr) !=
			    VMS_LOCALUNIT
#endif	/* VMS && VMS_LOCALUNIT */
				) {
				typelocal = peer;
				if (!(peer->flags & FLAG_PREFER))
					continue; /* no local clock */
#ifdef LOCKCLOCK
				else
					sys_prefer = peer;
#endif /* LOCKCLOCK */
			}
			if (peer->sstclktype == CTL_SST_TS_TELEPHONE) {
				typeacts = peer;
				if (!(peer->flags & FLAG_PREFER))
					continue; /* no acts */
			}

			/*
			 * If we get this far, the peer can stay on the
			 * island, but does not yet have the immunity
			 * idol.
			 */
			peer->status = CTL_PST_SEL_SANE;
			peer_list[nlist++] = peer;

			/*
			 * Insert each interval endpoint on the sorted
			 * list.
			 */
			e = peer->offset;	 /* Upper end */
			f = root_distance(peer);
			e = e + f;
			for (i = nl3 - 1; i >= 0; i--) {
				if (e >= endpoint[indx[i]].val)
					break;
				indx[i + 3] = indx[i];
			}
			indx[i + 3] = nl3;
			endpoint[nl3].type = 1;
			endpoint[nl3++].val = e;

			e = e - f;		/* Center point */
			for (; i >= 0; i--) {
				if (e >= endpoint[indx[i]].val)
					break;
				indx[i + 2] = indx[i];
			}
			indx[i + 2] = nl3;
			endpoint[nl3].type = 0;
			endpoint[nl3++].val = e;

			e = e - f;		/* Lower end */
			for (; i >= 0; i--) {
				if (e >= endpoint[indx[i]].val)
					break;
				indx[i + 1] = indx[i];
			}
			indx[i + 1] = nl3;
			endpoint[nl3].type = -1;
			endpoint[nl3++].val = e;
		}
	}
#ifdef DEBUG
	if (debug > 2)
		for (i = 0; i < nl3; i++)
			printf("select: endpoint %2d %.6f\n",
			   endpoint[indx[i]].type,
			   endpoint[indx[i]].val);
#endif
	/*
	 * This is the actual algorithm that cleaves the truechimers
	 * from the falsetickers. The original algorithm was described
	 * in Keith Marzullo's dissertation, but has been modified for
	 * better accuracy.
	 *
	 * Briefly put, we first assume there are no falsetickers, then
	 * scan the candidate list first from the low end upwards and
	 * then from the high end downwards. The scans stop when the
	 * number of intersections equals the number of candidates less
	 * the number of falsetickers. If this doesn't happen for a
	 * given number of falsetickers, we bump the number of
	 * falsetickers and try again. If the number of falsetickers
	 * becomes equal to or greater than half the number of
	 * candidates, the Albanians have won the Byzantine wars and
	 * correct synchronization is not possible.
	 *
	 * Here, nlist is the number of candidates and allow is the
	 * number of falsetickers.
	 */
	low = 1e9;
	high = -1e9;
	for (allow = 0; 2 * allow < nlist; allow++) {
		int	found;

		/*
		 * Bound the interval (low, high) as the largest
		 * interval containing points from presumed truechimers.
		 */
		found = 0;
		n = 0;
		for (i = 0; i < nl3; i++) {
			low = endpoint[indx[i]].val;
			n -= endpoint[indx[i]].type;
			if (n >= nlist - allow)
				break;
			if (endpoint[indx[i]].type == 0)
				found++;
		}
		n = 0;
		for (j = nl3 - 1; j >= 0; j--) {
			high = endpoint[indx[j]].val;
			n += endpoint[indx[j]].type;
			if (n >= nlist - allow)
				break;
			if (endpoint[indx[j]].type == 0)
				found++;
		}

		/*
		 * If the number of candidates found outside the
		 * interval is greater than the number of falsetickers,
		 * then at least one truechimer is outside the interval,
		 * so go around again. This is what makes this algorithm
		 * different than Marzullo's.
		 */
		if (found > allow)
			continue;

		/*
		 * If an interval containing truechimers is found, stop.
		 * If not, increase the number of falsetickers and go
		 * around again.
		 */
		if (high > low)
			break;
	}

	/*
	 * If no survivors remain at this point, check if the local
	 * clock or modem drivers have been found. If so, nominate one
	 * of them as the only survivor. Otherwise, give up and leave
	 * the island to the rats.
	 */
	if (high <= low) {
		if (typeacts != 0) {
			typeacts->status = CTL_PST_SEL_SANE;
			peer_list[0] = typeacts;
			nlist = 1;
		} else if (typelocal != 0) {
			typelocal->status = CTL_PST_SEL_SANE;
			peer_list[0] = typelocal;
			nlist = 1;
		} else {
			if (osys_peer != NULL) {
				sys_poll = NTP_MINPOLL;
				NLOG(NLOG_SYNCSTATUS)
				    msyslog(LOG_INFO,
				    "no servers reachable");
				report_event(EVNT_PEERSTCHG, NULL);
			}
			if (osurv > 0)
				resetmanycast();
			return;
		}
	}

	/*
	 * We can only trust the survivors if the number of candidates
	 * sys_minsane is at least the number required to detect and
	 * cast out one falsticker. For the Byzantine agreement
	 * algorithm used here, that number is 4; however, the default
	 * sys_minsane is 1 to speed initial synchronization. Careful
	 * operators will tinker the value to 4 and use at least that
	 * number of synchronization sources.
	 */
	if (nlist < sys_minsane)
		return;

	/*
	 * Clustering algorithm. Construct candidate list in order first
	 * by stratum then by root distance, but keep only the best
	 * NTP_MAXCLOCK of them. Scan the list to find falsetickers, who
	 * leave the island immediately. If a falseticker is not
	 * configured, his association raft is drowned as well, but only
	 * if at at least eight poll intervals have gone. We must leave
	 * at least one peer to collect the million bucks.
	 *
	 * Note the hysteresis gimmick that increases the effective
	 * distance for those rascals that have not made the final cut.
	 * This is to discourage clockhopping. Note also the prejudice
	 * against lower stratum peers if the floor is elevated.
	 */
	j = 0;
	for (i = 0; i < nlist; i++) {
		peer = peer_list[i];
		if (nlist > 1 && (peer->offset <= low || peer->offset >=
		    high)) {
			if (!(peer->flags & FLAG_CONFIG))
				unpeer(peer);
			continue;
		}
		peer->status = CTL_PST_SEL_DISTSYSPEER;
		d = peer->stratum;
		if (d < sys_floor)
			d += sys_floor;
		if (d > sys_ceiling)
			d = STRATUM_UNSPEC;
		d = root_distance(peer) + d * MAXDISTANCE;
		d *= 1. - peer->hyst;
		if (j >= NTP_MAXCLOCK) {
			if (d >= synch[j - 1])
				continue;
			else
				j--;
		}
		for (k = j; k > 0; k--) {
			if (d >= synch[k - 1])
				break;
			peer_list[k] = peer_list[k - 1];
			error[k] = error[k - 1];
			synch[k] = synch[k - 1];
		}
		peer_list[k] = peer;
		error[k] = peer->jitter;
		synch[k] = d;
		j++;
	}
	nlist = j;
	if (nlist == 0) {
#ifdef DEBUG
		if (debug)
			printf("clock_select: empty intersection interval\n");
#endif
		return;
	}
	for (i = 0; i < nlist; i++) {
		peer_list[i]->status = CTL_PST_SEL_SELCAND;

#ifdef DEBUG
		if (debug > 2)
			printf("select: %s distance %.6f jitter %.6f\n",
			    ntoa(&peer_list[i]->srcadr), synch[i],
			    SQRT(error[i]));
#endif
	}

	/*
	 * Now, vote outlyers off the island by select jitter weighted
	 * by root dispersion. Continue voting as long as there are more
	 * than sys_minclock survivors and the minimum select jitter
	 * squared is greater than the maximum peer jitter squared. Stop
	 * if we are about to discard a prefer peer, who of course has
	 * the immunity idol.
	 */
	while (1) {
		d = 1e9;
		e = -1e9;
		k = 0;
		for (i = 0; i < nlist; i++) {
			if (error[i] < d)
				d = error[i];
			f = 0;
			if (nlist > 1) {
				for (j = 0; j < nlist; j++)
					f += DIFF(peer_list[j]->offset,
					    peer_list[i]->offset);
				f /= nlist - 1;
			}
			if (f * synch[i] > e) {
				sys_selerr = f;
				e = f * synch[i];
				k = i;
			}
		}
		f = max(sys_selerr, SQUARE(LOGTOD(sys_precision))); 
		if (nlist <= sys_minclock || f <= d ||
		    peer_list[k]->flags & FLAG_PREFER)
			break;
#ifdef DEBUG
		if (debug > 2)
			printf(
			    "select: drop %s select %.6f jitter %.6f\n",
			    ntoa(&peer_list[k]->srcadr),
			    SQRT(sys_selerr), SQRT(d));
#endif
		if (!(peer_list[k]->flags & FLAG_CONFIG) &&
		    peer_list[k]->hmode == MODE_CLIENT)
			unpeer(peer_list[k]);
		for (j = k + 1; j < nlist; j++) {
			peer_list[j - 1] = peer_list[j];
			error[j - 1] = error[j];
		}
		nlist--;
	}

	/*
	 * What remains is a list usually not greater than sys_minclock
	 * peers. We want only a peer at the lowest stratum to become
	 * the system peer, although all survivors are eligible for the
	 * combining algorithm. First record their order, diddle the
	 * flags and clamp the poll intervals. Then, consider each peer
	 * in turn and OR the leap bits on the assumption that, if some
	 * of them honk nonzero bits, they must know what they are
	 * doing. Check for prefer and pps peers at any stratum. Check
	 * if the old system peer is among the peers at the lowest
	 * stratum. Note that the head of the list is at the lowest
	 * stratum and that unsynchronized peers cannot survive this
	 * far.
	 *
	 * Fiddle for hysteresis. Pump it up for a peer only if the peer
	 * stratum is at least the floor and there are enough survivors.
	 * This minimizes the pain when tossing out rascals beneath the
	 * floorboard. Don't count peers with stratum above the ceiling.
	 * Manycast is sooo complicated.
	 */
	leap_consensus = 0;
	for (i = nlist - 1; i >= 0; i--) {
		peer = peer_list[i];
		leap_consensus |= peer->leap;
		peer->status = CTL_PST_SEL_SYNCCAND;
		peer->rank++;
		peer->flags |= FLAG_SYSPEER;
		if (peer->stratum >= sys_floor && osurv >= sys_minclock)
			peer->hyst = HYST;
		else
			peer->hyst = 0;
		if (peer->stratum <= sys_ceiling)
			sys_survivors++;
		if (peer->flags & FLAG_PREFER)
			sys_prefer = peer;
		if (peer->refclktype == REFCLK_ATOM_PPS &&
		    peer->stratum < STRATUM_UNSPEC)
			typepps = peer;
		if (peer->stratum == peer_list[0]->stratum && peer ==
		    osys_peer)
			typesystem = peer;
	}

	/*
	 * In manycast client mode we may have spooked a sizeable number
	 * of peers that we don't need. If there are at least
	 * sys_minclock of them, the manycast message will be turned
	 * off. By the time we get here we nay be ready to prune some of
	 * them back, but we want to make sure all the candicates have
	 * had a chance. If they didn't pass the sanity and intersection
	 * tests, they have already been voted off the island.
	 */
	if (sys_survivors < sys_minclock && osurv >= sys_minclock)
		resetmanycast();

	/*
	 * Mitigation rules of the game. There are several types of
	 * peers that make a difference here: (1) prefer local peers
	 * (type REFCLK_LOCALCLOCK with FLAG_PREFER) or prefer modem
	 * peers (type REFCLK_NIST_ATOM etc with FLAG_PREFER), (2) pps
	 * peers (type REFCLK_ATOM_PPS), (3) remaining prefer peers
	 * (flag FLAG_PREFER), (4) the existing system peer, if any, (5)
	 * the head of the survivor list. Note that only one peer can be
	 * declared prefer. The order of preference is in the order
	 * stated. Note that all of these must be at the lowest stratum,
	 * i.e., the stratum of the head of the survivor list.
	 */
	if (sys_prefer)
		sw = sys_prefer->refclktype == REFCLK_LOCALCLOCK ||
		    sys_prefer->sstclktype == CTL_SST_TS_TELEPHONE ||
		    !typepps;
	else
		sw = 0;
	if (sw) {
		sys_peer = sys_prefer;
		sys_peer->status = CTL_PST_SEL_SYSPEER;
		sys_offset = sys_peer->offset;
		sys_error = SQRT(sys_peer->jitter);
#ifdef DEBUG
		if (debug > 1)
			printf("select: prefer offset %.6f\n",
			    sys_offset);
#endif
	}
#ifndef LOCKCLOCK
	  else if (typepps) {
		sys_peer = typepps;
		sys_peer->status = CTL_PST_SEL_PPS;
		sys_offset = sys_peer->offset;
		sys_error = SQRT(sys_peer->jitter);
		if (!pps_control)
			NLOG(NLOG_SYSEVENT)
			    msyslog(LOG_INFO, "pps sync enabled");
		pps_control = current_time;
#ifdef DEBUG
		if (debug > 1)
			printf("select: pps offset %.6f\n",
			    sys_offset);
#endif
	} else {
		if (typesystem)
			sys_peer = osys_peer;
		else
			sys_peer = peer_list[0];
		sys_peer->status = CTL_PST_SEL_SYSPEER;
		sys_peer->rank++;
		sys_offset = clock_combine(peer_list, nlist);
		sys_error = SQRT(sys_peer->jitter + sys_selerr);
#ifdef DEBUG
		if (debug > 1)
			printf("select: combine offset %.6f\n",
			   sys_offset);
#endif
	}
#endif /* LOCKCLOCK */
	if (osys_peer != sys_peer) {
		char *src;

		if (sys_peer == NULL)
			sys_peer_refid = 0;
		else
			sys_peer_refid = addr2refid(&sys_peer->srcadr);
		report_event(EVNT_PEERSTCHG, NULL);

#ifdef REFCLOCK
                if (ISREFCLOCKADR(&sys_peer->srcadr))
                        src = refnumtoa(&sys_peer->srcadr);
                else
#endif
                        src = ntoa(&sys_peer->srcadr);
		NLOG(NLOG_SYNCSTATUS)
		    msyslog(LOG_INFO, "synchronized to %s, stratum=%d", src,
			    sys_peer->stratum);
	}
	clock_update();
}

/*
 * clock_combine - combine offsets from selected peers
 */
static double
clock_combine(
	struct peer **peers,
	int	npeers
	)
{
	int	i;
	double	x, y, z;

	y = z = 0;
	for (i = 0; i < npeers; i++) {
		x = root_distance(peers[i]);
		y += 1. / x;
		z += peers[i]->offset / x;
	}
	return (z / y);
}

/*
 * root_distance - compute synchronization distance from peer to root
 */
static double
root_distance(
	struct peer *peer
	)
{
	/*
	 * Careful squeak here. The value returned must be greater than
	 * zero blamed on the peer jitter, which must be at least the
	 * square of sys_precision.
	 */
	return ((peer->rootdelay + peer->delay) / 2 +
	    peer->rootdispersion + peer->disp + clock_phi *
	    (current_time - peer->update) + SQRT(peer->jitter));
}

/*
 * peer_xmit - send packet for persistent association.
 */
static void
peer_xmit(
	struct peer *peer	/* peer structure pointer */
	)
{
	struct pkt xpkt;	/* transmit packet */
	int	sendlen, authlen;
	keyid_t	xkeyid = 0;		/* transmit key ID */
	l_fp	xmt_tx;

	/*
	 * Initialize transmit packet header fields.
	 */
	xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, peer->version,
	    peer->hmode);
	xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
	xpkt.ppoll = peer->hpoll;
	xpkt.precision = sys_precision;
	xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
	xpkt.rootdispersion = HTONS_FP(DTOUFP(sys_rootdispersion));
	xpkt.refid = sys_refid;
	HTONL_FP(&sys_reftime, &xpkt.reftime);
	HTONL_FP(&peer->org, &xpkt.org);
	HTONL_FP(&peer->rec, &xpkt.rec);

	/*
	 * If the received packet contains a MAC, the transmitted packet
	 * is authenticated and contains a MAC. If not, the transmitted
	 * packet is not authenticated.
	 *
	 * In the current I/O semantics the default interface is set
	 * until after receiving a packet and setting the right
	 * interface. So, the first packet goes out unauthenticated.
	 * That's why the really icky test next is here.
	 */
	sendlen = LEN_PKT_NOMAC;
	if (!(peer->flags & FLAG_AUTHENABLE)) {
		get_systime(&peer->xmt);
		HTONL_FP(&peer->xmt, &xpkt.xmt);
		sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl],
		    &xpkt, sendlen);
		peer->sent++;
#ifdef DEBUG
		if (debug)
			printf("transmit: at %ld %s->%s mode %d\n",
			    current_time, stoa(&peer->dstadr->sin),
			    stoa(&peer->srcadr), peer->hmode);
#endif
		return;
	}

	/*
	 * The received packet contains a MAC, so the transmitted packet
	 * must be authenticated. If autokey is enabled, fuss with the
	 * various modes; otherwise, private key cryptography is used.
	 */
#ifdef OPENSSL
	if (crypto_flags && (peer->flags & FLAG_SKEY)) {
		struct exten *exten;	/* extension field */
		u_int	opcode;

		/*
		 * The Public Key Dance (PKD): Cryptographic credentials
		 * are contained in extension fields, each including a
		 * 4-octet length/code word followed by a 4-octet
		 * association ID and optional additional data. Optional
		 * data includes a 4-octet data length field followed by
		 * the data itself. Request messages are sent from a
		 * configured association; response messages can be sent
		 * from a configured association or can take the fast
		 * path without ever matching an association. Response
		 * messages have the same code as the request, but have
		 * a response bit and possibly an error bit set. In this
		 * implementation, a message may contain no more than
		 * one command and no more than one response.
		 *
		 * Cryptographic session keys include both a public and
		 * a private componet. Request and response messages
		 * using extension fields are always sent with the
		 * private component set to zero. Packets without
		 * extension fields indlude the private component when
		 * the session key is generated.
		 */
		while (1) {
		
			/*
			 * Allocate and initialize a keylist if not
			 * already done. Then, use the list in inverse
			 * order, discarding keys once used. Keep the
			 * latest key around until the next one, so
			 * clients can use client/server packets to
			 * compute propagation delay.
			 *
			 * Note that once a key is used from the list,
			 * it is retained in the key cache until the
			 * next key is used. This is to allow a client
			 * to retrieve the encrypted session key
			 * identifier to verify authenticity.
			 *
			 * If for some reason a key is no longer in the
			 * key cache, a birthday has happened and the
			 * pseudo-random sequence is probably broken. In
			 * that case, purge the keylist and regenerate
			 * it.
			 */
			if (peer->keynumber == 0)
				make_keylist(peer, peer->dstadr);
			else
				peer->keynumber--;
			xkeyid = peer->keylist[peer->keynumber];
			if (authistrusted(xkeyid))
				break;
			else
				key_expire(peer);
		}
		peer->keyid = xkeyid;
		switch (peer->hmode) {

		/*
		 * In broadcast server mode the autokey values are
		 * required by the broadcast clients. Push them when a
		 * new keylist is generated; otherwise, push the
		 * association message so the client can request them at
		 * other times.
		 */
		case MODE_BROADCAST:
			if (peer->flags & FLAG_ASSOC)
				exten = crypto_args(peer, CRYPTO_AUTO |
				    CRYPTO_RESP, NULL);
			else
				exten = crypto_args(peer, CRYPTO_ASSOC |
				    CRYPTO_RESP, NULL);
			sendlen += crypto_xmit(&xpkt, &peer->srcadr,
			    sendlen, exten, 0);
			free(exten);
			break;

		/*
		 * In symmetric modes the digest, certificate, agreement
		 * parameters, cookie and autokey values are required.
		 * The leapsecond table is optional. But, a passive peer
		 * will not believe the active peer until the latter has
		 * synchronized, so the agreement must be postponed
		 * until then. In any case, if a new keylist is
		 * generated, the autokey values are pushed.
		 */
		case MODE_ACTIVE:
		case MODE_PASSIVE:
			if (peer->cmmd != NULL) {
				peer->cmmd->associd =
				    htonl(peer->associd);
				sendlen += crypto_xmit(&xpkt,
				    &peer->srcadr, sendlen, peer->cmmd,
				    0);
				free(peer->cmmd);
				peer->cmmd = NULL;
			}
			exten = NULL;
			if (!peer->crypto)
				exten = crypto_args(peer, CRYPTO_ASSOC,
				    sys_hostname);
			else if (!(peer->crypto & CRYPTO_FLAG_VALID))
				exten = crypto_args(peer, CRYPTO_CERT,
				    peer->issuer);

			/*
			 * Identity. Note we have to sign the
			 * certificate before the cookie to avoid a
			 * deadlock when the passive peer is walking the
			 * certificate trail. Awesome.
			 */
			else if ((opcode = crypto_ident(peer)) != 0)
				exten = crypto_args(peer, opcode, NULL);
			else if (sys_leap != LEAP_NOTINSYNC &&
			   !(peer->crypto & CRYPTO_FLAG_SIGN))
				exten = crypto_args(peer, CRYPTO_SIGN,
				    sys_hostname);

			/*
			 * Autokey. We request the cookie only when the
			 * server and client are synchronized and
			 * signatures work both ways. On the other hand,
			 * the active peer needs the autokey values
			 * before then and when the passive peer is
			 * waiting for the active peer to synchronize.
			 * Any time we regenerate the key list, we offer
			 * the autokey values without being asked.
			 */
			else if (sys_leap != LEAP_NOTINSYNC &&
			    peer->leap != LEAP_NOTINSYNC &&
			    !(peer->crypto & CRYPTO_FLAG_AGREE))
				exten = crypto_args(peer, CRYPTO_COOK,
				    NULL);
			else if (peer->flags & FLAG_ASSOC)
				exten = crypto_args(peer, CRYPTO_AUTO |
				    CRYPTO_RESP, NULL);
			else if (!(peer->crypto & CRYPTO_FLAG_AUTO))
				exten = crypto_args(peer, CRYPTO_AUTO,
				    NULL);

			/*
			 * Postamble. We trade leapseconds only when the
			 * server and client are synchronized.
			 */
			else if (sys_leap != LEAP_NOTINSYNC &&
			    peer->leap != LEAP_NOTINSYNC &&
			    peer->crypto & CRYPTO_FLAG_TAI &&
			    !(peer->crypto & CRYPTO_FLAG_LEAP))
				exten = crypto_args(peer, CRYPTO_TAI,
				    NULL);
			if (exten != NULL) {
				sendlen += crypto_xmit(&xpkt,
				    &peer->srcadr, sendlen, exten, 0);
				free(exten);
			}
			break;

		/*
		 * In client mode the digest, certificate, agreement
		 * parameters and cookie are required. The leapsecond
		 * table is optional. If broadcast client mode, the
		 * autokey values are required as well. In broadcast
		 * client mode, these values must be acquired during the
		 * client/server exchange to avoid having to wait until
		 * the next key list regeneration. Otherwise, the poor
		 * dude may die a lingering death until becoming
		 * unreachable and attempting rebirth.
		 *
		 * If neither the server or client have the agreement
		 * parameters, the protocol transmits the cookie in the
		 * clear. If the server has the parameters, the client
		 * requests them and the protocol blinds it using the
		 * agreed key. It is a protocol error if the client has
		 * the parameters but the server does not.
		 */
		case MODE_CLIENT:
			if (peer->cmmd != NULL) {
				peer->cmmd->associd =
				    htonl(peer->associd);
				sendlen += crypto_xmit(&xpkt,
				    &peer->srcadr, sendlen, peer->cmmd,
				    0);
				free(peer->cmmd);
				peer->cmmd = NULL;
			}
			exten = NULL;
			if (!peer->crypto)
				exten = crypto_args(peer, CRYPTO_ASSOC,
				    sys_hostname);
			else if (!(peer->crypto & CRYPTO_FLAG_VALID))
				exten = crypto_args(peer, CRYPTO_CERT,
				    peer->issuer);

			/*
			 * Identity.
			 */
			else if ((opcode = crypto_ident(peer)) != 0)
				exten = crypto_args(peer, opcode, NULL);

			/*
			 * Autokey
			 */
			else if (!(peer->crypto & CRYPTO_FLAG_AGREE))
				exten = crypto_args(peer, CRYPTO_COOK,
				    NULL);
			else if (!(peer->crypto & CRYPTO_FLAG_AUTO) &&
			    (peer->cast_flags & MDF_BCLNT))
				exten = crypto_args(peer, CRYPTO_AUTO,
				    NULL);

			/*
			 * Postamble. We can sign the certificate here,
			 * since there is no chance of deadlock.
			 */
			else if (sys_leap != LEAP_NOTINSYNC &&
			   !(peer->crypto & CRYPTO_FLAG_SIGN))
				exten = crypto_args(peer, CRYPTO_SIGN,
				    sys_hostname);
			else if (sys_leap != LEAP_NOTINSYNC &&
			    peer->crypto & CRYPTO_FLAG_TAI &&
			    !(peer->crypto & CRYPTO_FLAG_LEAP))
				exten = crypto_args(peer, CRYPTO_TAI,
				    NULL);
			if (exten != NULL) {
				sendlen += crypto_xmit(&xpkt,
				    &peer->srcadr, sendlen, exten, 0);
				free(exten);
			}
			break;
		}

		/*
		 * If extension fields are present, we must use a
		 * private value of zero and force min poll interval.
		 * Most intricate.
		 */
		if (sendlen > LEN_PKT_NOMAC)
			session_key(&peer->dstadr->sin, &peer->srcadr,
			    xkeyid, 0, 2);
	} 
#endif /* OPENSSL */
	xkeyid = peer->keyid;
	get_systime(&peer->xmt);
	L_ADD(&peer->xmt, &sys_authdelay);
	HTONL_FP(&peer->xmt, &xpkt.xmt);
	authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
	if (authlen == 0) {
		msyslog(LOG_INFO,
		    "transmit: encryption key %d not found", xkeyid);
		if (peer->flags & FLAG_CONFIG)
			peer_clear(peer, "NKEY");
		else
			unpeer(peer);
		return;
	}
	sendlen += authlen;
#ifdef OPENSSL
	if (xkeyid > NTP_MAXKEY)
		authtrust(xkeyid, 0);
#endif /* OPENSSL */
	get_systime(&xmt_tx);
	if (sendlen > sizeof(xpkt)) {
		msyslog(LOG_ERR, "buffer overflow %u", sendlen);
		exit (-1);
	}
	sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl], &xpkt,
	    sendlen);

	/*
	 * Calculate the encryption delay. Keep the minimum over
	 * the latest two samples.
	 */
	L_SUB(&xmt_tx, &peer->xmt);
	L_ADD(&xmt_tx, &sys_authdelay);
	sys_authdly[1] = sys_authdly[0];
	sys_authdly[0] = xmt_tx.l_uf;
	if (sys_authdly[0] < sys_authdly[1])
		sys_authdelay.l_uf = sys_authdly[0];
	else
		sys_authdelay.l_uf = sys_authdly[1];
	peer->sent++;
#ifdef OPENSSL
#ifdef DEBUG
	if (debug)
		printf(
		    "transmit: at %ld %s->%s mode %d keyid %08x len %d mac %d index %d\n",
		    current_time, ntoa(&peer->dstadr->sin),
		    ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen -
		    authlen, authlen, peer->keynumber);
#endif
#else
#ifdef DEBUG
	if (debug)
		printf(
		    "transmit: at %ld %s->%s mode %d keyid %08x len %d mac %d\n",
		    current_time, ntoa(&peer->dstadr->sin),
		    ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen -
		    authlen, authlen);
#endif
#endif /* OPENSSL */
}


/*
 * fast_xmit - Send packet for nonpersistent association. Note that
 * neither the source or destination can be a broadcast address.
 */
static void
fast_xmit(
	struct recvbuf *rbufp,	/* receive packet pointer */
	int	xmode,		/* transmit mode */
	keyid_t	xkeyid,		/* transmit key ID */
	int	mask		/* restrict mask */
	)
{
	struct pkt xpkt;		/* transmit packet structure */
	struct pkt *rpkt;		/* receive packet structure */
	l_fp	xmt_ts;			/* timestamp */
	l_fp	xmt_tx;			/* timestamp after authent */
	int	sendlen, authlen;
#ifdef OPENSSL
	u_int32	temp32;
#endif

	/*
	 * Initialize transmit packet header fields from the receive
	 * buffer provided. We leave some fields intact as received. If
	 * the gazinta was from a multicast address, the gazouta must go
	 * out another way.
	 */
	rpkt = &rbufp->recv_pkt;
	if (rbufp->dstadr->flags & INT_MULTICAST)
		rbufp->dstadr = findinterface(&rbufp->recv_srcadr);

	/*
	 * If the packet has picked up a restriction due to either
	 * access denied or rate exceeded, decide what to do with it.
	 */
	if (mask & (RES_DONTTRUST | RES_LIMITED)) {
		char	*code = "????";

		if (mask & RES_LIMITED) {
			sys_limitrejected++;
			code = "RATE";
		} else if (mask & RES_DONTTRUST) {
			sys_restricted++;
			code = "DENY";
		}

		/*
		 * Here we light up a kiss-of-death packet. Note the
		 * rate limit on these packets. Once a second initialize
		 * a bucket counter. Every packet sent decrements the
		 * counter until reaching zero. If the counter is zero,
		 * drop the kod.
		 */
		if (sys_kod == 0 || !(mask & RES_DEMOBILIZE))
			return;

		sys_kod--;
		memcpy(&xpkt.refid, code, 4);
		xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC,
		    PKT_VERSION(rpkt->li_vn_mode), xmode);
		xpkt.stratum = STRATUM_UNSPEC;
	} else {
		xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap,
		    PKT_VERSION(rpkt->li_vn_mode), xmode);
		xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
		xpkt.refid = sys_refid;
	}
	xpkt.ppoll = rpkt->ppoll;
	xpkt.precision = sys_precision;
	xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
	xpkt.rootdispersion =
	    HTONS_FP(DTOUFP(sys_rootdispersion));
	HTONL_FP(&sys_reftime, &xpkt.reftime);
	xpkt.org = rpkt->xmt;
	HTONL_FP(&rbufp->recv_time, &xpkt.rec);

	/*
	 * If the received packet contains a MAC, the transmitted packet
	 * is authenticated and contains a MAC. If not, the transmitted
	 * packet is not authenticated.
	 */
	sendlen = LEN_PKT_NOMAC;
	if (rbufp->recv_length == sendlen) {
		get_systime(&xmt_ts);
		HTONL_FP(&xmt_ts, &xpkt.xmt);
		sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt,
		    sendlen);
#ifdef DEBUG
		if (debug)
			printf("transmit: at %ld %s->%s mode %d\n",
			    current_time, stoa(&rbufp->dstadr->sin),
			    stoa(&rbufp->recv_srcadr), xmode);
#endif
		return;
	}

	/*
	 * The received packet contains a MAC, so the transmitted packet
	 * must be authenticated. For private-key cryptography, use the
	 * predefined private keys to generate the cryptosum. For
	 * autokey cryptography, use the server private value to
	 * generate the cookie, which is unique for every source-
	 * destination-key ID combination.
	 */
#ifdef OPENSSL
	if (xkeyid > NTP_MAXKEY) {
		keyid_t cookie;

		/*
		 * The only way to get here is a reply to a legitimate
		 * client request message, so the mode must be
		 * MODE_SERVER. If an extension field is present, there
		 * can be only one and that must be a command. Do what
		 * needs, but with private value of zero so the poor
		 * jerk can decode it. If no extension field is present,
		 * use the cookie to generate the session key.
		 */
		cookie = session_key(&rbufp->recv_srcadr,
		    &rbufp->dstadr->sin, 0, sys_private, 0);
		if (rbufp->recv_length >= (int)(sendlen + MAX_MAC_LEN + 2 *
		    sizeof(u_int32))) {
			session_key(&rbufp->dstadr->sin,
			    &rbufp->recv_srcadr, xkeyid, 0, 2);
			temp32 = CRYPTO_RESP;
			rpkt->exten[0] |= htonl(temp32);
			sendlen += crypto_xmit(&xpkt,
			    &rbufp->recv_srcadr, sendlen,
			    (struct exten *)rpkt->exten, cookie);
		} else {
			session_key(&rbufp->dstadr->sin,
			    &rbufp->recv_srcadr, xkeyid, cookie, 2);
		}
	}
#endif /* OPENSSL */
	get_systime(&xmt_ts);
	L_ADD(&xmt_ts, &sys_authdelay);
	HTONL_FP(&xmt_ts, &xpkt.xmt);
	authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
	sendlen += authlen;
#ifdef OPENSSL
	if (xkeyid > NTP_MAXKEY)
		authtrust(xkeyid, 0);
#endif /* OPENSSL */
	get_systime(&xmt_tx);
	if (sendlen > sizeof(xpkt)) {
		msyslog(LOG_ERR, "buffer overflow %u", sendlen);
		exit (-1);
	}
	sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen);

	/*
	 * Calculate the encryption delay. Keep the minimum over the
	 * latest two samples.
	 */
	L_SUB(&xmt_tx, &xmt_ts);
	L_ADD(&xmt_tx, &sys_authdelay);
	sys_authdly[1] = sys_authdly[0];
	sys_authdly[0] = xmt_tx.l_uf;
	if (sys_authdly[0] < sys_authdly[1])
		sys_authdelay.l_uf = sys_authdly[0];
	else
		sys_authdelay.l_uf = sys_authdly[1];
#ifdef DEBUG
	if (debug)
		printf(
		    "transmit: at %ld %s->%s mode %d keyid %08x len %d mac %d\n",
		    current_time, ntoa(&rbufp->dstadr->sin),
		    ntoa(&rbufp->recv_srcadr), xmode, xkeyid, sendlen -
		    authlen, authlen);
#endif
}


#ifdef OPENSSL
/*
 * key_expire - purge the key list
 */
void
key_expire(
	struct peer *peer	/* peer structure pointer */
	)
{
	int i;

	if (peer->keylist != NULL) {
		for (i = 0; i <= peer->keynumber; i++)
			authtrust(peer->keylist[i], 0);
		free(peer->keylist);
		peer->keylist = NULL;
	}
	value_free(&peer->sndval);
	peer->keynumber = 0;
#ifdef DEBUG
	if (debug)
		printf("key_expire: at %lu\n", current_time);
#endif
}
#endif /* OPENSSL */


/*
 * Determine if the peer is unfit for synchronization
 *
 * A peer is unfit for synchronization if
 * > not reachable
 * > a synchronization loop would form
 * > never been synchronized
 * > stratum undefined or too high
 * > too long without synchronization
 * > designated noselect
 */
static int			/* 0 if no, 1 if yes */
peer_unfit(
	struct peer *peer	/* peer structure pointer */
	)
{
	return (!peer->reach || (peer->stratum > 1 && peer->refid ==
	    peer->dstadr->addr_refid) || peer->leap == LEAP_NOTINSYNC ||
	    peer->stratum >= STRATUM_UNSPEC || peer->flags &
	    FLAG_NOSELECT);
}


/*
 * Find the precision of this particular machine
 */
#define MINSTEP 100e-9		/* minimum clock increment (s) */
#define MAXSTEP 20e-3		/* maximum clock increment (s) */
#define MINLOOPS 5		/* minimum number of step samples */

/*
 * This routine calculates the system precision, defined as the minimum
 * of a sequency of differences between successive readings of the
 * system clock. However, if the system clock can be read more than once
 * during a tick interval, the difference can be zero or one LSB unit,
 * where the LSB corresponds to one nanosecond or one microsecond.
 * Conceivably, if some other process preempts this one and reads the
 * clock, the difference can be more than one LSB unit.
 *
 * For hardware clock frequencies of 10 MHz or less, we assume the
 * logical clock advances only at the hardware clock tick. For higher
 * frequencies, we assume the logical clock can advance no more than 100
 * nanoseconds between ticks.
 */
int
default_get_precision(void)
{
	l_fp	val;		/* current seconds fraction */
	l_fp	last;		/* last seconds fraction */
	l_fp	diff;		/* difference */
	double	tick;		/* computed tick value */
	double	dtemp;		/* scratch */
	int	i;		/* log2 precision */

	/*
	 * Loop to find tick value in nanoseconds. Toss out outlyer
	 * values less than the minimun tick value. In wacky cases, use
	 * the default maximum value.
	 */
	get_systime(&last);
	tick = MAXSTEP;
	for (i = 0; i < MINLOOPS;) {
		get_systime(&val);
		diff = val;
		L_SUB(&diff, &last);
		last = val;
		LFPTOD(&diff, dtemp);
		if (dtemp < MINSTEP)
			continue;
		i++;
		if (dtemp < tick)
			tick = dtemp;
	}

	/*
	 * Find the nearest power of two.
	 */
	NLOG(NLOG_SYSEVENT)
	    msyslog(LOG_INFO, "precision = %.3f usec", tick * 1e6);
	for (i = 0; tick <= 1; i++)
		tick *= 2;
	if (tick - 1. > 1. - tick / 2)
		i--;
	return (-i);
}


/*
 * kod_proto - called once per second to limit kiss-of-death packets
 */
void
kod_proto(void)
{
	sys_kod = sys_kod_rate;
}


/*
 * init_proto - initialize the protocol module's data
 */
void
init_proto(void)
{
	l_fp	dummy;
	int	i;

	/*
	 * Fill in the sys_* stuff.  Default is don't listen to
	 * broadcasting, authenticate.
	 */
	sys_leap = LEAP_NOTINSYNC;
	sys_stratum = STRATUM_UNSPEC;
	memcpy(&sys_refid, "INIT", 4);
	sys_precision = (s_char)default_get_precision();
	sys_rootdelay = 0;
	sys_rootdispersion = 0;
	L_CLR(&sys_reftime);
	sys_peer = NULL;
	sys_survivors = 0;
	get_systime(&dummy);
	sys_manycastserver = 0;
	sys_bclient = 0;
	sys_bdelay = DEFBROADDELAY;
	sys_calldelay = BURST_DELAY;
	sys_authenticate = 1;
	L_CLR(&sys_authdelay);
	sys_authdly[0] = sys_authdly[1] = 0;
	sys_stattime = 0;
	proto_clr_stats();
	for (i = 0; i < MAX_TTL; i++) {
		sys_ttl[i] = (u_char)((i * 256) / MAX_TTL);
		sys_ttlmax = i;
	}
#ifdef OPENSSL
	sys_automax = 1 << NTP_AUTOMAX;
#endif /* OPENSSL */

	/*
	 * Default these to enable
	 */
	ntp_enable = 1;
#ifndef KERNEL_FLL_BUG
	kern_enable = 1;
#endif
	pps_enable = 0;
	stats_control = 1;
}


/*
 * proto_config - configure the protocol module
 */
void
proto_config(
	int	item,
	u_long	value,
	double	dvalue,
	struct sockaddr_storage* svalue
	)
{
	/*
	 * Figure out what he wants to change, then do it
	 */
	switch (item) {

	/*
	 * Turn on/off kernel discipline.
	 */
	case PROTO_KERNEL:
		kern_enable = (int)value;
		break;

	/*
	 * Turn on/off clock discipline.
	 */
	case PROTO_NTP:
		ntp_enable = (int)value;
		break;

	/*
	 * Turn on/off monitoring.
	 */
	case PROTO_MONITOR:
		if (value)
			mon_start(MON_ON);
		else
			mon_stop(MON_ON);
		break;

	/*
	 * Turn on/off statistics.
	 */
	case PROTO_FILEGEN:
		stats_control = (int)value;
		break;

	/*
	 * Turn on/off facility to listen to broadcasts.
	 */
	case PROTO_BROADCLIENT:
		sys_bclient = (int)value;
		if (value)
			io_setbclient();
		else
			io_unsetbclient();
		break;

	/*
	 * Add muliticast group address.
	 */
	case PROTO_MULTICAST_ADD:
		if (svalue)
		    io_multicast_add(*svalue);
		break;

	/*
	 * Delete multicast group address.
	 */
	case PROTO_MULTICAST_DEL:
		if (svalue)
		    io_multicast_del(*svalue);
		break;

	/*
	 * Set default broadcast delay.
	 */
	case PROTO_BROADDELAY:
		sys_bdelay = dvalue;
		break;

	/*
	 * Set modem call delay.
	 */
	case PROTO_CALLDELAY:
		sys_calldelay = (int)value;
		break;

	/*
	 * Require authentication to mobilize ephemeral associations.
	 */
	case PROTO_AUTHENTICATE:
		sys_authenticate = (int)value;
		break;

	/*
	 * Turn on/off PPS discipline.
	 */
	case PROTO_PPS:
		pps_enable = (int)value;
		break;

	/*
	 * Set the minimum number of survivors.
	 */
	case PROTO_MINCLOCK:
		sys_minclock = (int)dvalue;
		break;

	/*
	 * Set the minimum number of candidates.
	 */
	case PROTO_MINSANE:
		sys_minsane = (int)dvalue;
		break;

	/*
	 * Set the stratum floor.
	 */
	case PROTO_FLOOR:
		sys_floor = (int)dvalue;
		break;

	/*
	 * Set the stratum ceiling.
	 */
	case PROTO_CEILING:
		sys_ceiling = (int)dvalue;
		break;

	/*
	 * Set the cohort switch.
	 */
	case PROTO_COHORT:
		sys_cohort= (int)dvalue;
		break;
	/*
	 * Set the adjtime() resolution (s).
	 */
	case PROTO_ADJ:
		sys_tick = dvalue;
		break;

#ifdef REFCLOCK
	/*
	 * Turn on/off refclock calibrate
	 */
	case PROTO_CAL:
		cal_enable = (int)value;
		break;
#endif
	default:

		/*
		 * Log this error.
		 */
		msyslog(LOG_INFO,
			"proto_config: illegal item %d, value %ld",
			item, value);
	}
}


/*
 * proto_clr_stats - clear protocol stat counters
 */
void
proto_clr_stats(void)
{
	sys_stattime = current_time;
	sys_received = 0;
	sys_processed = 0;
	sys_newversionpkt = 0;
	sys_oldversionpkt = 0;
	sys_unknownversion = 0;
	sys_restricted = 0;
	sys_badlength = 0;
	sys_badauth = 0;
	sys_limitrejected = 0;
}
