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freebsd-skq/contrib/ntp/ntpd/ntp_proto.c

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/*
* ntp_proto.c - NTP version 4 protocol machinery
*
* $FreeBSD$
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include "ntpd.h"
#include "ntp_stdlib.h"
#include "ntp_unixtime.h"
#include "ntp_control.h"
#include "ntp_string.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; /* distance to current sync source */
double sys_rootdispersion; /* dispersion of system clock */
u_int32 sys_refid; /* reference source for local clock */
static double sys_offset; /* current local clock offset */
l_fp sys_reftime; /* time we were last updated */
struct peer *sys_peer; /* our current peer */
u_long sys_automax; /* maximum session key lifetime */
/*
* Nonspecified system state variables.
*/
int sys_bclient; /* we set our time to broadcasts */
double sys_bdelay; /* broadcast client default delay */
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_maxd; /* select error (squares) */
static double sys_epsil; /* system error (squares) */
u_long sys_private; /* private value for session seed */
int sys_manycastserver; /* 1 => respond to manycast client pkts */
/*
* Statistics counters
*/
u_long sys_stattime; /* time when we started recording */
u_long sys_badstratum; /* packets with invalid stratum */
u_long sys_oldversionpkt; /* old version packets received */
u_long sys_newversionpkt; /* new version packets received */
u_long sys_unknownversion; /* don't know version packets */
u_long sys_badlength; /* packets with bad length */
u_long sys_processed; /* packets processed */
u_long sys_badauth; /* packets dropped because of auth */
u_long sys_limitrejected; /* pkts rejected due to client count per net */
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, u_long));
static void clock_update P((void));
int default_get_precision P((void));
#ifdef MD5
static void make_keylist P((struct peer *));
#endif /* MD5 */
/*
* transmit - Transmit Procedure. See Section 3.4.2 of the
* specification.
*/
void
transmit(
struct peer *peer /* peer structure pointer */
)
{
int hpoll;
hpoll = peer->hpoll;
if (peer->burst == 0) {
u_char oreach;
/*
* Determine reachability and diddle things if we
* haven't heard from the host for a while. If the peer
* is not configured and not likely to stay around,
* we exhaust it.
*/
oreach = peer->reach;
if (oreach & 0x01)
peer->valid++;
if (oreach & 0x80)
peer->valid--;
if (!(peer->flags & FLAG_CONFIG) && peer->valid >
NTP_SHIFT / 2 && (peer->reach & 0x80) &&
peer->status < CTL_PST_SEL_SYNCCAND)
peer->reach = 0;
peer->reach <<= 1;
if (peer->reach == 0) {
/*
* If this is an uncofigured association and
* has become unreachable, demobilize it.
*/
if (oreach != 0) {
report_event(EVNT_UNREACH, peer);
peer->timereachable = current_time;
peer_clear(peer);
if (!(peer->flags & FLAG_CONFIG)) {
unpeer(peer);
return;
}
}
/*
* We would like to respond quickly when the
* peer comes back to life. If the probes since
* becoming unreachable are less than
* NTP_UNREACH, clamp the poll interval to the
* minimum. In order to minimize the network
* traffic, the interval gradually ramps up the
* the maximum after that.
*/
peer->ppoll = peer->maxpoll;
if (peer->unreach < NTP_UNREACH) {
if (peer->hmode == MODE_CLIENT)
peer->unreach++;
hpoll = peer->minpoll;
} else {
hpoll++;
}
if (peer->flags & FLAG_BURST)
peer->burst = 2;
} else {
/*
* Here the peer is reachable. If there is no
* system peer or if the stratum of the system
* peer is greater than this peer, clamp the
* poll interval to the minimum. If less than
* two samples are in the reachability register,
* reduce the interval; if more than six samples
* are in the register, increase the interval.
*/
peer->unreach = 0;
if (sys_peer == 0)
hpoll = peer->minpoll;
else if (sys_peer->stratum > peer->stratum)
hpoll = peer->minpoll;
if ((peer->reach & 0x03) == 0) {
clock_filter(peer, 0., 0., MAXDISPERSE);
clock_select();
}
if (peer->valid <= 2)
hpoll--;
else if (peer->valid >= NTP_SHIFT - 2)
hpoll++;
if (peer->flags & FLAG_BURST)
peer->burst = NTP_SHIFT;
}
} else {
peer->burst--;
if (peer->burst == 0) {
if (peer->flags & FLAG_MCAST2) {
peer->flags &= ~FLAG_BURST;
peer->hmode = MODE_BCLIENT;
}
clock_select();
poll_update(peer, hpoll);
return;
}
}
/*
* We need to be very careful about honking uncivilized time. If
* not operating in broadcast mode, honk in all except broadcast
* client mode. If operating in broadcast mode and synchronized
* to a real source, honk except when the peer is the local-
* clock driver and the prefer flag is not set. In other words,
* in broadcast mode we never honk unless known to be
* synchronized to real time.
*/
if (peer->hmode != MODE_BROADCAST) {
if (peer->hmode != MODE_BCLIENT)
peer_xmit(peer);
} else if (sys_peer != 0 && sys_leap != LEAP_NOTINSYNC) {
if (!(sys_peer->refclktype == REFCLK_LOCALCLOCK &&
!(sys_peer->flags & FLAG_PREFER)))
peer_xmit(peer);
}
peer->outdate = current_time;
poll_update(peer, hpoll);
}
/*
* receive - Receive Procedure. See section 3.4.3 in the specification.
*/
void
receive(
struct recvbuf *rbufp
)
{
register struct peer *peer;
register struct pkt *pkt;
int hismode;
int oflags;
int restrict_mask;
int has_mac; /* has MAC field */
int authlen; /* length of MAC field */
int is_authentic; /* cryptosum ok */
int is_mystic; /* session key exists */
int is_error; /* parse error */
/* u_long pkeyid; */
u_long skeyid, tkeyid;
struct peer *peer2;
int retcode = AM_NOMATCH;
/*
* Monitor the packet and get restrictions
*/
ntp_monitor(rbufp);
restrict_mask = restrictions(&rbufp->recv_srcadr);
#ifdef DEBUG
if (debug > 1)
printf("receive: from %s restrict %02x\n",
ntoa(&rbufp->recv_srcadr), restrict_mask);
#endif
if (restrict_mask & RES_IGNORE)
return;
/*
* Discard packets with invalid version number.
*/
pkt = &rbufp->recv_pkt;
if (PKT_VERSION(pkt->li_vn_mode) >= NTP_VERSION)
sys_newversionpkt++;
else if (PKT_VERSION(pkt->li_vn_mode) >= NTP_OLDVERSION)
sys_oldversionpkt++;
else {
sys_unknownversion++;
return;
}
/*
* Restrict control/private mode packets. Note that packet
* length has to be checked in the control/private mode protocol
* module.
*/
if (PKT_MODE(pkt->li_vn_mode) == MODE_PRIVATE) {
if (restrict_mask & RES_NOQUERY)
return;
process_private(rbufp, ((restrict_mask &
RES_NOMODIFY) == 0));
return;
}
if (PKT_MODE(pkt->li_vn_mode) == MODE_CONTROL) {
if (restrict_mask & RES_NOQUERY)
return;
process_control(rbufp, restrict_mask);
return;
}
/*
* Restrict revenue packets.
*/
if (restrict_mask & RES_DONTSERVE)
return;
/*
* See if we only accept limited number of clients from the net
* this guy is from. Note: the flag is determined dynamically
* within restrictions()
*/
if (restrict_mask & RES_LIMITED) {
sys_limitrejected++;
return;
}
/*
* If we are not a broadcast client, ignore broadcast packets.
*/
if ((PKT_MODE(pkt->li_vn_mode) == MODE_BROADCAST &&
!sys_bclient))
return;
/*
* This is really awful ugly. We figure out whether an extension
* field is present and then measure the MAC size. If the number
* of words following the packet header is less than or equal to
* 5, no extension field is present and these words constitute
* the MAC. If the number of words is greater than 5, an
* extension field is present and the first word contains the
* length of the extension field and the MAC follows that.
*/
has_mac = 0;
/* pkeyid = 0; */
skeyid = tkeyid = 0;
authlen = LEN_PKT_NOMAC;
has_mac = rbufp->recv_length - authlen;
if (has_mac <= 5 * sizeof(u_int32)) {
skeyid = (u_long)ntohl(pkt->keyid1) & 0xffffffff;
} else {
authlen += (u_long)ntohl(pkt->keyid1) & 0xffffffff;
has_mac = rbufp->recv_length - authlen;
if (authlen <= 0) {
sys_badlength++;
return;
}
/*
* Note that keyid3 is actually the key ident of the
* MAC itself.
*/
/* pkeyid = (u_long)ntohl(pkt->keyid2) & 0xffffffff; */
skeyid = tkeyid = (u_long)ntohl(pkt->keyid3) &
0xffffffff;
}
/*
* Figure out his mode and validate it.
*/
hismode = (int)PKT_MODE(pkt->li_vn_mode);
if (PKT_VERSION(pkt->li_vn_mode) == NTP_OLDVERSION && hismode ==
0) {
/*
* Easy. If it is from the NTP port it is
* a sym act, else client.
*/
if (SRCPORT(&rbufp->recv_srcadr) == NTP_PORT)
hismode = MODE_ACTIVE;
else
hismode = MODE_CLIENT;
} else {
if (hismode != MODE_ACTIVE && hismode != MODE_PASSIVE &&
hismode != MODE_SERVER && hismode != MODE_CLIENT &&
hismode != MODE_BROADCAST)
return;
}
/*
* If he included a mac field, decrypt it to see if it is
* authentic.
*/
is_authentic = is_mystic = 0;
if (has_mac == 0) {
#ifdef DEBUG
if (debug)
printf("receive: at %ld from %s mode %d\n",
current_time, ntoa(&rbufp->recv_srcadr),
hismode);
#endif
} else {
is_mystic = authistrusted(skeyid);
#ifdef MD5
if (skeyid > NTP_MAXKEY && !is_mystic) {
/*
* For multicast mode, generate the session key
* and install in the key cache. For client
* mode, generate the session key for the
* unicast address. For server mode, the session
* key should already be in the key cache, since
* it was generated when the last request was
* sent.
*/
if (hismode == MODE_BROADCAST) {
tkeyid = session_key(
ntohl((&rbufp->recv_srcadr)->sin_addr.s_addr),
ntohl(rbufp->dstadr->bcast.sin_addr.s_addr),
skeyid, (u_long)(4 * (1 << pkt->ppoll)));
} else if (hismode != MODE_SERVER) {
tkeyid = session_key(
ntohl((&rbufp->recv_srcadr)->sin_addr.s_addr),
ntohl(rbufp->dstadr->sin.sin_addr.s_addr),
skeyid, (u_long)(4 * (1 << pkt->ppoll)));
}
}
#endif /* MD5 */
/*
* Compute the cryptosum. Note a clogging attack may
* succceed in bloating the key cache.
*/
if (authdecrypt(skeyid, (u_int32 *)pkt, authlen,
has_mac))
is_authentic = 1;
else
sys_badauth++;
#ifdef DEBUG
if (debug)
printf(
"receive: at %ld %s mode %d keyid %08lx mac %d auth %d\n",
current_time, ntoa(&rbufp->recv_srcadr),
hismode, skeyid, has_mac, is_authentic);
#endif
}
/*
* Find the peer. This will return a null if this guy isn't in
* the database.
*/
peer = findpeer(&rbufp->recv_srcadr, rbufp->dstadr, rbufp->fd,
hismode, &retcode);
/*
* The new association matching rules are driven by a table
* specified in ntp.h. We have replaced the *default* behaviour
* of replying to bogus packets in server mode in this version.
* A packet must now match an association in order to be
* processed. In the event that no association exists, then an
* association is mobilized if need be. Two different
* associations can be mobilized a) passive associations b)
* client associations due to broadcasts or manycasts.
*/
is_error = 0;
switch (retcode) {
case AM_FXMIT:
/*
* If the client is configured purely as a broadcast
* client and not as an manycast server, it has no
* business being a server. Simply go home. Otherwise,
* send a MODE_SERVER response and go home. Note that we
* don't do a authentication check here, since we can't
* set the system clock; but, we do set the key ID to
* zero to tell the caller about this.
*/
if (!sys_bclient || sys_manycastserver) {
if (is_authentic)
fast_xmit(rbufp, MODE_SERVER, skeyid);
else
fast_xmit(rbufp, MODE_SERVER, 0);
}
/*
* We can't get here if an association is mobilized, so
* just toss the key, if appropriate.
*/
if (!is_mystic && skeyid > NTP_MAXKEY)
authtrust(skeyid, 0);
return;
case AM_MANYCAST:
/*
* This could be in response to a multicast packet sent
* by the "manycast" mode association. Find peer based
* on the originate timestamp in the packet. Note that
* we don't mobilize a new association, unless the
* packet is properly authenticated. The response must
* be properly authenticated and it's darn funny of the
* manycaster isn't around now.
*/
if ((sys_authenticate && !is_authentic)) {
is_error = 1;
break;
}
peer2 = (struct peer *)findmanycastpeer(&pkt->org);
if (peer2 == 0) {
is_error = 1;
break;
}
/*
* Create a new association and copy the peer variables
* to it. If something goes wrong, carefully pry the new
* association away and return its marbles to the candy
* store.
*/
peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
MODE_CLIENT, PKT_VERSION(pkt->li_vn_mode),
NTP_MINDPOLL, NTP_MAXDPOLL, 0, skeyid);
if (peer == 0) {
is_error = 1;
break;
}
peer_config_manycast(peer2, peer);
break;
case AM_ERR:
/*
* Something bad happened. Dirty floor will be mopped by
* the code at the end of this adventure.
*/
is_error = 1;
break;
case AM_NEWPASS:
/*
* Okay, we're going to keep him around. Allocate him
* some memory. But, don't do that unless the packet is
* properly authenticated.
*/
if ((sys_authenticate && !is_authentic)) {
is_error = 1;
break;
}
peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
MODE_PASSIVE, PKT_VERSION(pkt->li_vn_mode),
NTP_MINDPOLL, NTP_MAXDPOLL, 0, skeyid);
break;
case AM_NEWBCL:
/*
* Broadcast client being set up now. Do this only if
* the packet is properly authenticated.
*/
if ((restrict_mask & RES_NOPEER) || !sys_bclient ||
(sys_authenticate && !is_authentic)) {
is_error = 1;
break;
}
peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
MODE_MCLIENT, PKT_VERSION(pkt->li_vn_mode),
NTP_MINDPOLL, NTP_MAXDPOLL, 0, skeyid);
if (peer == 0)
break;
peer->flags |= FLAG_MCAST1 | FLAG_MCAST2 | FLAG_BURST;
peer->hmode = MODE_CLIENT;
break;
case AM_POSSBCL:
case AM_PROCPKT:
/*
* It seems like it is okay to process the packet now
*/
break;
default:
/*
* shouldn't be getting here, but simply return anyway!
*/
is_error = 1;
}
if (is_error) {
/*
* Error stub. If we get here, something broke. We
* scuttle the autokey if necessary and sink the ship.
* This can occur only upon mobilization, so we can
* throw the structure away without fear of breaking
* anything.
*/
if (!is_mystic && skeyid > NTP_MAXKEY)
authtrust(skeyid, 0);
if (peer != 0)
if (!(peer->flags & FLAG_CONFIG))
unpeer(peer);
#ifdef DEBUG
if (debug)
printf("match error code %d assoc %d\n",
retcode, peer_associations);
#endif
return;
}
/*
* If the peer isn't configured, set his keyid and authenable
* status based on the packet.
*/
oflags = peer->flags;
peer->timereceived = current_time;
if (!(peer->flags & FLAG_CONFIG) && has_mac) {
peer->flags |= FLAG_AUTHENABLE;
if (skeyid > NTP_MAXKEY) {
if (peer->flags & FLAG_MCAST2)
peer->keyid = skeyid;
else
peer->flags |= FLAG_SKEY;
}
}
/*
* Determine if this guy is basically trustable. If not, flush
* the bugger. If this is the first packet that is
* authenticated, flush the clock filter. This is to foil
* clogging attacks that might starve the poor dear.
*/
peer->flash = 0;
if (is_authentic)
peer->flags |= FLAG_AUTHENTIC;
else
peer->flags &= ~FLAG_AUTHENTIC;
if (peer->hmode == MODE_BROADCAST && (restrict_mask &
RES_DONTTRUST))
peer->flash |= TEST10; /* access denied */
if (peer->flags & FLAG_AUTHENABLE) {
if (!(peer->flags & FLAG_AUTHENTIC))
peer->flash |= TEST5; /* auth failed */
else if (skeyid == 0)
peer->flash |= TEST9; /* peer not auth */
else if (!(oflags & FLAG_AUTHENABLE)) {
peer_clear(peer);
report_event(EVNT_PEERAUTH, peer);
}
}
if ((peer->flash & ~(u_int)TEST9) != 0) {
/*
* The packet is bogus, so we throw it away before
* becoming a denial-of-service hazard. We don't throw
* the current association away if it is configured or
* if it has prior reachable friends.
*/
if (!is_mystic && skeyid > NTP_MAXKEY)
authtrust(skeyid, 0);
if (!(peer->flags & FLAG_CONFIG) && peer->reach == 0)
unpeer(peer);
#ifdef DEBUG
if (debug)
printf(
"invalid packet 0x%02x code %d assoc %d\n",
peer->flash, retcode, peer_associations);
#endif
return;
}
#ifdef MD5
/*
* The autokey dance. The cha-cha requires that the hash of the
* current session key matches the previous key identifier.
* Heaps of trouble if the steps falter.
*/
if (skeyid > NTP_MAXKEY) {
int i;
/*
* In the case of a new autokey, verify the hash matches
* one of the previous four hashes. If not, raise the
* authentication flasher and hope the next one works.
*/
if (hismode == MODE_SERVER) {
peer->pkeyid = peer->keyid;
} else if (peer->flags & FLAG_MCAST2) {
if (peer->pkeyid > NTP_MAXKEY)
authtrust(peer->pkeyid, 0);
for (i = 0; i < 4 && tkeyid != peer->pkeyid;
i++) {
tkeyid = session_key(
ntohl((&rbufp->recv_srcadr)->sin_addr.s_addr),
ntohl(rbufp->dstadr->bcast.sin_addr.s_addr),
tkeyid, 0);
}
} else {
if (peer->pkeyid > NTP_MAXKEY)
authtrust(peer->pkeyid, 0);
for (i = 0; i < 4 && tkeyid != peer->pkeyid;
i++) {
tkeyid = session_key(
ntohl((&rbufp->recv_srcadr)->sin_addr.s_addr),
ntohl(rbufp->dstadr->sin.sin_addr.s_addr),
tkeyid, 0);
}
}
#ifdef XXX /* temp until certificate code is mplemented */
if (tkeyid != peer->pkeyid)
peer->flash |= TEST9; /* peer not authentic */
#endif
peer->pkeyid = skeyid;
}
#endif /* MD5 */
/*
* Gawdz, it's come to this. Process the dang packet. If
* something breaks and the association doesn't deserve to live,
* toss it. Be careful in active mode and return a packet
* anyway.
*/
process_packet(peer, pkt, &(rbufp->recv_time));
if (!(peer->flags & FLAG_CONFIG) && peer->reach == 0) {
if (peer->hmode == MODE_PASSIVE) {
if (is_authentic)
fast_xmit(rbufp, MODE_PASSIVE, skeyid);
else
fast_xmit(rbufp, MODE_PASSIVE, 0);
}
unpeer(peer);
}
}
/*
* 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.
*/
int
process_packet(
register struct peer *peer,
register struct pkt *pkt,
l_fp *recv_ts
)
{
l_fp t10, t23;
double p_offset, p_del, p_disp;
double dtemp;
l_fp p_rec, p_xmt, p_org, p_reftime;
l_fp ci;
int pmode;
/*
* Swap header fields and keep the books.
*/
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);
if (PKT_MODE(pkt->li_vn_mode) != MODE_BROADCAST)
NTOHL_FP(&pkt->org, &p_org);
else
p_org = peer->rec;
peer->rec = *recv_ts;
peer->ppoll = pkt->ppoll;
pmode = PKT_MODE(pkt->li_vn_mode);
/*
* Test for old or duplicate packets (tests 1 through 3).
*/
if (L_ISHIS(&peer->org, &p_xmt)) /* count old packets */
peer->oldpkt++;
if (L_ISEQU(&peer->org, &p_xmt)) /* test 1 */
peer->flash |= TEST1; /* duplicate packet */
if (PKT_MODE(pkt->li_vn_mode) != MODE_BROADCAST) {
if (!L_ISEQU(&peer->xmt, &p_org)) { /* test 2 */
peer->bogusorg++;
peer->flash |= TEST2; /* bogus packet */
}
if (L_ISZERO(&p_rec) || L_ISZERO(&p_org))
peer->flash |= TEST3; /* unsynchronized */
} else {
if (L_ISZERO(&p_org))
peer->flash |= TEST3; /* unsynchronized */
}
peer->org = p_xmt;
/*
* Test for valid header (tests 5 through 10)
*/
ci = p_xmt;
L_SUB(&ci, &p_reftime);
LFPTOD(&ci, dtemp);
if (PKT_LEAP(pkt->li_vn_mode) == LEAP_NOTINSYNC || /* test 6 */
PKT_TO_STRATUM(pkt->stratum) >= NTP_MAXSTRATUM ||
dtemp < 0)
peer->flash |= TEST6; /* peer clock unsynchronized */
if (!(peer->flags & FLAG_CONFIG) && sys_peer != 0) { /* test 7 */
if (PKT_TO_STRATUM(pkt->stratum) > sys_stratum) {
peer->flash |= TEST7; /* peer stratum too high */
sys_badstratum++;
}
}
if (fabs(p_del) >= MAXDISPERSE /* test 8 */
|| p_disp >= MAXDISPERSE)
peer->flash |= TEST8; /* delay/dispersion too high */
/*
* If the packet header is invalid (tests 5 through 10), exit.
* XXX we let TEST9 sneak by until the certificate code is
* implemented, but only to mobilize the association.
*/
if (peer->flash & (TEST5 | TEST6 | TEST7 | TEST8 | TEST10)) {
#ifdef DEBUG
if (debug)
printf(
"invalid packet header 0x%02x mode %d\n",
peer->flash, pmode);
#endif
return (0);
}
/*
* Valid header; update our state.
*/
record_raw_stats(&peer->srcadr, &peer->dstadr->sin,
&p_org, &p_rec, &p_xmt, &peer->rec);
peer->leap = PKT_LEAP(pkt->li_vn_mode);
peer->pmode = pmode; /* unspec */
peer->stratum = PKT_TO_STRATUM(pkt->stratum);
peer->precision = pkt->precision;
peer->rootdelay = p_del;
peer->rootdispersion = p_disp;
peer->refid = pkt->refid;
peer->reftime = p_reftime;
if (peer->reach == 0) {
report_event(EVNT_REACH, peer);
peer->timereachable = current_time;
}
peer->reach |= 1;
poll_update(peer, peer->hpoll);
/*
* 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.
*
* c = ((t2 - t3) + (t1 - t0)) / 2
* d = (t2 - t3) - (t1 - t0)
* e = (org - rec) (seconds only)
*/
t10 = p_xmt; /* compute t1 - t0 */
L_SUB(&t10, &peer->rec);
t23 = p_rec; /* compute t2 - t3 */
L_SUB(&t23, &p_org);
ci = t10;
p_disp = CLOCK_PHI * (peer->rec.l_ui - p_org.l_ui);
/*
* 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
* client/server mode, calculate the clock offset, using the
* engineered refinement algorithms, while also receiving
* broadcasts. When a broadcast is received in client/server
* mode, we calculate a correction factor to use after switching
* back to broadcast mode. We know NTP_SKEWFACTOR == 16, which
* accounts for the simplified ei calculation.
*
* If FLAG_MCAST2 is set, we are a broadcast/multicast client.
* If FLAG_MCAST1 is set, we haven't calculated the propagation
* delay. If hmode is MODE_CLIENT, we haven't set the local
* clock in client/server mode. Initially, we come up
* MODE_CLIENT. When the clock is first updated and FLAG_MCAST2
* is set, we switch from MODE_CLIENT to MODE_BCLIENT.
*/
if (pmode == MODE_BROADCAST) {
if (peer->flags & FLAG_MCAST1) {
if (peer->hmode == MODE_BCLIENT)
peer->flags &= ~FLAG_MCAST1;
LFPTOD(&ci, p_offset);
peer->estbdelay = peer->offset - p_offset;
return (1);
}
DTOLFP(peer->estbdelay, &t10);
L_ADD(&ci, &t10);
p_del = peer->delay;
} else {
L_ADD(&ci, &t23);
L_RSHIFT(&ci);
L_SUB(&t23, &t10);
LFPTOD(&t23, p_del);
}
LFPTOD(&ci, p_offset);
if (fabs(p_del) >= MAXDISPERSE || p_disp >= MAXDISPERSE) /* test 4 */
peer->flash |= TEST4; /* delay/dispersion too big */
/*
* If the packet data are invalid (tests 1 through 4), exit.
*/
if (peer->flash) {
#ifdef DEBUG
if (debug)
printf("invalid packet data 0x%02x mode %d\n",
peer->flash, pmode);
#endif
return(1);
}
/*
* This one is valid. Mark it so, give it to clock_filter().
*/
clock_filter(peer, p_offset, p_del, fabs(p_disp));
clock_select();
record_peer_stats(&peer->srcadr, ctlpeerstatus(peer),
peer->offset, peer->delay, peer->disp,
SQRT(peer->variance));
return(1);
}
/*
* clock_update - Called at system process update intervals.
*/
static void
clock_update(void)
{
u_char oleap;
u_char ostratum;
int i;
struct peer *peer;
/*
* Reset/adjust the system clock. Do this only if there is a
* system peer and we haven't seen that peer lately. Watch for
* timewarps here.
*/
if (sys_peer == 0)
return;
if (sys_peer->pollsw == FALSE || sys_peer->burst > 0)
return;
sys_peer->pollsw = FALSE;
#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, sys_epsil)) {
case -1:
/*
* Clock is too screwed up. Just exit for now.
*/
report_event(EVNT_SYSFAULT, (struct peer *)0);
exit(1);
/*NOTREACHED*/
case 1:
/*
* Clock was stepped. Clear filter registers
* of all peers.
*/
for (i = 0; i < HASH_SIZE; i++) {
for (peer = peer_hash[i]; peer != 0;
peer =peer->next)
peer_clear(peer);
}
NLOG(NLOG_SYNCSTATUS)
msyslog(LOG_INFO, "synchronisation lost");
sys_peer = 0;
sys_stratum = STRATUM_UNSPEC;
report_event(EVNT_CLOCKRESET, (struct peer *)0);
break;
default:
/*
* Update the system stratum, leap bits, root delay,
* root dispersion, reference ID and reference time. We
* also update select dispersion and max frequency
* error.
*/
sys_stratum = sys_peer->stratum + 1;
if (sys_stratum == 1)
sys_refid = sys_peer->refid;
else
sys_refid = sys_peer->srcadr.sin_addr.s_addr;
sys_reftime = sys_peer->rec;
sys_rootdelay = sys_peer->rootdelay +
fabs(sys_peer->delay);
sys_leap = leap_consensus;
}
if (oleap != sys_leap)
report_event(EVNT_SYNCCHG, (struct peer *)0);
if (ostratum != sys_stratum)
report_event(EVNT_PEERSTCHG, (struct peer *)0);
}
/*
* poll_update - update peer poll interval. See Section 3.4.9 of the
* spec.
*/
void
poll_update(
struct peer *peer,
int hpoll
)
{
long update;
/*
* The wiggle-the-poll-interval dance. Broadcasters dance only
* the minpoll beat. Reference clock partners sit this one out.
* Dancers surviving the clustering algorithm beat to the system
* clock. Broadcast clients are usually lead by their broadcast
* partner, but faster in the initial mating dance.
*/
if (peer->hmode == MODE_BROADCAST) {
peer->hpoll = peer->minpoll;
} else if (peer->flags & FLAG_SYSPEER) {
peer->hpoll = sys_poll;
} else {
if (hpoll > peer->maxpoll)
peer->hpoll = peer->maxpoll;
else if (hpoll < peer->minpoll)
peer->hpoll = peer->minpoll;
else
peer->hpoll = hpoll;
}
if (peer->burst > 0) {
if (peer->nextdate != current_time)
return;
if (peer->flags & FLAG_REFCLOCK)
peer->nextdate++;
else if (peer->reach & 0x1)
peer->nextdate += RANDPOLL(BURST_INTERVAL2);
else
peer->nextdate += RANDPOLL(BURST_INTERVAL1);
} else {
update = max(min(peer->ppoll, peer->hpoll),
peer->minpoll);
peer->nextdate = peer->outdate + RANDPOLL(update);
}
#ifdef DEBUG
if (debug > 1)
printf("poll_update: at %lu %s poll %d burst %d last %lu next %lu\n",
current_time, ntoa(&peer->srcadr), hpoll,
peer->burst, peer->outdate, peer->nextdate);
#endif
}
/*
* clear - clear peer filter registers. See Section 3.4.8 of the spec.
*/
void
peer_clear(
register struct peer *peer
)
{
register int i;
memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO);
peer->estbdelay = sys_bdelay;
peer->hpoll = peer->minpoll;
peer->pollsw = FALSE;
peer->variance = MAXDISPERSE;
peer->epoch = current_time;
for (i = 0; i < NTP_SHIFT; i++) {
peer->filter_order[i] = i;
peer->filter_disp[i] = MAXDISPERSE;
peer->filter_epoch[i] = current_time;
}
poll_update(peer, peer->minpoll);
/*
* Since we have a chance to correct possible funniness in
* our selection of interfaces on a multihomed host, do so
* by setting us to no particular interface.
* WARNING: do so only in non-broadcast mode!
*/
if (peer->hmode != MODE_BROADCAST)
peer->dstadr = any_interface;
}
/*
* clock_filter - add incoming clock sample to filter register and run
* the filter procedure to find the best sample.
*/
void
clock_filter(
register struct peer *peer,
double sample_offset,
double sample_delay,
double sample_disp
)
{
register int i, j, k, n = 0;
register u_char *ord;
double distance[NTP_SHIFT];
double x, y, z, off;
/*
* Update error bounds and calculate distances. Also initialize
* sort index vector.
*/
x = CLOCK_PHI * (current_time - peer->update);
peer->update = current_time;
ord = peer->filter_order;
j = peer->filter_nextpt;
for (i = 0; i < NTP_SHIFT; i++) {
peer->filter_disp[j] += x;
if (peer->filter_disp[j] > MAXDISPERSE)
peer->filter_disp[j] = MAXDISPERSE;
distance[i] = fabs(peer->filter_delay[j]) / 2 +
peer->filter_disp[j];
ord[i] = j;
if (--j < 0)
j += NTP_SHIFT;
}
/*
* Insert the new sample at the beginning of the register.
*/
peer->filter_offset[peer->filter_nextpt] = sample_offset;
peer->filter_delay[peer->filter_nextpt] = sample_delay;
x = LOGTOD(peer->precision) + LOGTOD(sys_precision) +
sample_disp;
peer->filter_disp[peer->filter_nextpt] = min(x, MAXDISPERSE);
peer->filter_epoch[peer->filter_nextpt] = current_time;
distance[0] = min(x + fabs(sample_delay) / 2, MAXDISTANCE);
peer->filter_nextpt++;
if (peer->filter_nextpt >= NTP_SHIFT)
peer->filter_nextpt = 0;
/*
* Sort the samples in the register by distance. The winning
* sample will be in ord[0]. Sort the samples only if they
* are younger than the Allen intercept.
*/
y = min(allan_xpt, NTP_SHIFT * ULOGTOD(sys_poll));
for (n = 0; n < NTP_SHIFT && current_time -
peer->filter_epoch[ord[n]] <= y; n++) {
for (j = 0; j < n; j++) {
if (distance[j] > distance[n]) {
x = distance[j];
k = ord[j];
distance[j] = distance[n];
ord[j] = ord[n];
distance[n] = x;
ord[n] = k;
}
}
}
/*
* Compute the error bound and standard error.
*/
x = y = z = off = 0.;
for (i = NTP_SHIFT - 1; i >= 0; i--) {
x = NTP_FWEIGHT * (x + peer->filter_disp[ord[i]]);
if (i < n) {
z += 1. / distance[i];
off += peer->filter_offset[ord[i]] /
distance[i];
y += DIFF(peer->filter_offset[ord[i]],
peer->filter_offset[ord[0]]);
}
}
peer->delay = peer->filter_delay[ord[0]];
peer->variance = min(y / n, MAXDISPERSE);
peer->disp = min(x, MAXDISPERSE);
peer->epoch = current_time;
x = peer->offset;
if (peer->flags & FLAG_BURST)
peer->offset = off / z;
else
peer->offset = peer->filter_offset[ord[0]];
/*
* A new sample is useful only if it is younger than the last
* one used.
*/
if (peer->filter_epoch[ord[0]] > peer->epoch) {
#ifdef DEBUG
if (debug)
printf("clock_filter: discard %lu\n",
peer->filter_epoch[ord[0]] - peer->epoch);
#endif
return;
}
/*
* If the offset exceeds the dispersion 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 (fabs(x - peer->offset) > CLOCK_SGATE &&
peer->filter_epoch[ord[0]] - peer->epoch < (1 <<
(sys_poll + 1))) {
#ifdef DEBUG
if (debug)
printf("clock_filter: popcorn spike %.6f\n", x);
#endif
return;
}
peer->epoch = peer->filter_epoch[ord[0]];
peer->pollsw = TRUE;
#ifdef DEBUG
if (debug)
printf(
"clock_filter: offset %.6f delay %.6f disp %.6f std %.6f, age %lu\n",
peer->offset, peer->delay, peer->disp,
SQRT(peer->variance), current_time - peer->epoch);
#endif
}
/*
* clock_select - find the pick-of-the-litter clock
*/
void
clock_select(void)
{
register struct peer *peer;
int i;
int nlist, nl3;
double d, e, f;
int j;
int n;
int allow, found, k;
double high, low;
double synch[NTP_MAXCLOCK], error[NTP_MAXCLOCK];
struct peer *osys_peer;
struct peer *typeacts = 0;
struct peer *typelocal = 0;
struct peer *typepps = 0;
struct peer *typeprefer = 0;
struct peer *typesystem = 0;
static int list_alloc = 0;
static struct endpoint *endpoint = NULL;
static int *index = NULL;
static struct peer **peer_list = NULL;
static u_int endpoint_size = 0;
static u_int index_size = 0;
static u_int peer_list_size = 0;
/*
* Initialize. If a prefer peer does not survive this thing,
* the pps_update switch will remain zero.
*/
pps_update = 0;
nlist = 0;
low = 1e9;
high = -1e9;
for (n = 0; n < HASH_SIZE; n++)
nlist += peer_hash_count[n];
if (nlist > list_alloc) {
if (list_alloc > 0) {
free(endpoint);
free(index);
free(peer_list);
}
while (list_alloc < nlist) {
list_alloc += 5;
endpoint_size += 5 * 3 * sizeof *endpoint;
index_size += 5 * 3 * sizeof *index;
peer_list_size += 5 * sizeof *peer_list;
}
endpoint = (struct endpoint *)emalloc(endpoint_size);
index = (int *)emalloc(index_size);
peer_list = (struct peer **)emalloc(peer_list_size);
}
/*
* This first chunk of code is supposed to go through all
* peers we know about to find the peers which are most likely
* to succeed. We run through the list doing the sanity checks
* and trying to insert anyone who looks okay.
*/
nlist = nl3 = 0; /* none yet */
for (n = 0; n < HASH_SIZE; n++) {
for (peer = peer_hash[n]; peer != 0; peer = peer->next) {
peer->flags &= ~FLAG_SYSPEER;
peer->status = CTL_PST_SEL_REJECT;
if (peer->flags & FLAG_NOSELECT)
continue; /* noselect (survey) */
if (peer->reach == 0)
continue; /* unreachable */
if (peer->stratum > 1 && peer->refid ==
peer->dstadr->sin.sin_addr.s_addr)
continue; /* sync loop */
if (root_distance(peer) >= MAXDISTANCE + 2 *
CLOCK_PHI * ULOGTOD(sys_poll)) {
peer->seldisptoolarge++;
continue; /* noisy or broken */
}
/*
* Don't allow the local-clock or acts drivers
* in the kitchen at this point, unless the
* prefer peer. Do that later, but only if
* nobody else is around.
*/
if (peer->refclktype == REFCLK_LOCALCLOCK
#if defined(VMS) && defined(VMS_LOCALUNIT)
/* wjm: local unit VMS_LOCALUNIT taken seriously */
&& REFCLOCKUNIT(&peer->srcadr) != VMS_LOCALUNIT
#endif /* VMS && VMS_LOCALUNIT */
) {
typelocal = peer;
if (!(peer->flags & FLAG_PREFER))
continue; /* no local clock */
}
if (peer->sstclktype == CTL_SST_TS_TELEPHONE) {
typeacts = peer;
if (!(peer->flags & FLAG_PREFER))
continue; /* no acts */
}
/*
* If we get this far, we assume the peer is
* acceptable.
*/
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[index[i]].val)
break;
index[i + 3] = index[i];
}
index[i + 3] = nl3;
endpoint[nl3].type = 1;
endpoint[nl3++].val = e;
e = e - f; /* Center point */
for ( ; i >= 0; i--) {
if (e >= endpoint[index[i]].val)
break;
index[i + 2] = index[i];
}
index[i + 2] = nl3;
endpoint[nl3].type = 0;
endpoint[nl3++].val = e;
e = e - f; /* Lower end */
for ( ; i >= 0; i--) {
if (e >= endpoint[index[i]].val)
break;
index[i + 1] = index[i];
}
index[i + 1] = nl3;
endpoint[nl3].type = -1;
endpoint[nl3++].val = e;
}
}
#ifdef DEBUG
if (debug > 1)
for (i = 0; i < nl3; i++)
printf("select: endpoint %2d %.6f\n",
endpoint[index[i]].type, endpoint[index[i]].val);
#endif
i = 0;
j = nl3 - 1;
allow = nlist; /* falsetickers assumed */
found = 0;
while (allow > 0) {
allow--;
for (n = 0; i <= j; i++) {
n += endpoint[index[i]].type;
if (n < 0)
break;
if (endpoint[index[i]].type == 0)
found++;
}
for (n = 0; i <= j; j--) {
n += endpoint[index[j]].type;
if (n > 0)
break;
if (endpoint[index[j]].type == 0)
found++;
}
if (found > allow)
break;
low = endpoint[index[i++]].val;
high = endpoint[index[j--]].val;
}
/*
* If no survivors remain at this point, check if the acts or
* local clock drivers have been found. If so, nominate one of
* them as the only survivor. Otherwise, give up and declare us
* unsynchronized.
*/
if ((allow << 1) >= nlist) {
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 (sys_peer != 0) {
report_event(EVNT_PEERSTCHG,
(struct peer *)0);
NLOG(NLOG_SYNCSTATUS)
msyslog(LOG_INFO,
"synchronisation lost");
}
sys_peer = 0;
return;
}
}
#ifdef DEBUG
if (debug > 1)
printf("select: low %.6f high %.6f\n", low, high);
#endif
/*
* Clustering algorithm. Process intersection list to discard
* outlyers. Construct candidate list in cluster order
* determined by the sum of peer synchronization distance plus
* scaled stratum. We must find at least one peer.
*/
j = 0;
for (i = 0; i < nlist; i++) {
peer = peer_list[i];
if (nlist > 1 && (low >= peer->offset ||
peer->offset >= high))
continue;
peer->status = CTL_PST_SEL_CORRECT;
d = root_distance(peer) + peer->stratum * MAXDISPERSE;
if (j >= NTP_MAXCLOCK) {
if (d >= synch[j - 1])
continue;
else
j--;
}
for (k = j; k > 0; k--) {
if (d >= synch[k - 1])
break;
synch[k] = synch[k - 1];
peer_list[k] = peer_list[k - 1];
}
peer_list[k] = peer;
synch[k] = d;
j++;
}
nlist = j;
#ifdef DEBUG
if (debug > 1)
for (i = 0; i < nlist; i++)
printf("select: %s distance %.6f\n",
ntoa(&peer_list[i]->srcadr), synch[i]);
#endif
/*
* Now, prune outlyers by root dispersion. Continue as long as
* there are more than NTP_MINCLOCK survivors and the minimum
* select dispersion is greater than the maximum peer
* dispersion. Stop if we are about to discard a prefer peer.
*/
for (i = 0; i < nlist; i++) {
peer = peer_list[i];
error[i] = peer->variance;
if (i < NTP_CANCLOCK)
peer->status = CTL_PST_SEL_SELCAND;
else
peer->status = CTL_PST_SEL_DISTSYSPEER;
}
while (1) {
sys_maxd = 0;
d = error[0];
for (k = i = nlist - 1; i >= 0; i--) {
double sdisp = 0;
for (j = nlist - 1; j > 0; j--) {
sdisp = NTP_SWEIGHT * (sdisp +
DIFF(peer_list[i]->offset,
peer_list[j]->offset));
}
if (sdisp > sys_maxd) {
sys_maxd = sdisp;
k = i;
}
if (error[i] < d)
d = error[i];
}
#ifdef DEBUG
if (debug > 1)
printf(
"select: survivors %d select %.6f peer %.6f\n",
nlist, SQRT(sys_maxd), SQRT(d));
#endif
if (nlist <= NTP_MINCLOCK || sys_maxd <= d ||
peer_list[k]->flags & FLAG_PREFER)
break;
for (j = k + 1; j < nlist; j++) {
peer_list[j - 1] = peer_list[j];
error[j - 1] = error[j];
}
nlist--;
}
#ifdef DEBUG
if (debug > 1) {
for (i = 0; i < nlist; i++)
printf(
"select: %s offset %.6f, distance %.6f poll %d\n",
ntoa(&peer_list[i]->srcadr), peer_list[i]->offset,
synch[i], peer_list[i]->pollsw);
}
#endif
/*
* What remains is a list of not greater than NTP_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 the peers
* at the lowest stratum. Of these, OR the leap bits on the
* assumption that, if some of them honk nonzero bits, they must
* know what they are doing. Also, check for prefer and pps
* peers. If a prefer peer is found within clock_max, update the
* pps switch. Of the other peers not at the lowest stratum,
* check if the system peer is among them and, if found, zap
* him. We note that the head of the list is at the lowest
* stratum and that unsynchronized peers cannot survive this
* far.
*/
leap_consensus = 0;
for (i = nlist - 1; i >= 0; i--) {
peer_list[i]->status = CTL_PST_SEL_SYNCCAND;
peer_list[i]->flags |= FLAG_SYSPEER;
poll_update(peer_list[i], peer_list[i]->hpoll);
if (peer_list[i]->stratum == peer_list[0]->stratum) {
leap_consensus |= peer_list[i]->leap;
if (peer_list[i]->refclktype == REFCLK_ATOM_PPS)
typepps = peer_list[i];
if (peer_list[i] == sys_peer)
typesystem = peer_list[i];
if (peer_list[i]->flags & FLAG_PREFER) {
typeprefer = peer_list[i];
if (fabs(typeprefer->offset) <
clock_max)
pps_update = 1;
}
} else {
if (peer_list[i] == sys_peer)
sys_peer = 0;
}
}
/*
* 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.
*/
osys_peer = sys_peer;
if (typeprefer && (typeprefer->refclktype == REFCLK_LOCALCLOCK
|| typeprefer->sstclktype == CTL_SST_TS_TELEPHONE ||
!typepps)) {
sys_peer = typeprefer;
sys_peer->status = CTL_PST_SEL_SYSPEER;
sys_offset = sys_peer->offset;
sys_epsil = sys_peer->variance;
#ifdef DEBUG
if (debug > 1)
printf("select: prefer offset %.6f\n",
sys_offset);
#endif
} else if (typepps && pps_update) {
sys_peer = typepps;
sys_peer->status = CTL_PST_SEL_PPS;
sys_offset = sys_peer->offset;
sys_epsil = sys_peer->variance;
if (!pps_control)
NLOG(NLOG_SYSEVENT) /* conditional syslog */
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 = peer_list[0];
sys_peer->status = CTL_PST_SEL_SYSPEER;
sys_offset = clock_combine(peer_list, nlist);
sys_epsil = sys_peer->variance + sys_maxd;
#ifdef DEBUG
if (debug > 1)
printf("select: combine offset %.6f\n",
sys_offset);
#endif
}
if (osys_peer != sys_peer)
report_event(EVNT_PEERSTCHG, (struct peer *)0);
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
)
{
return ((fabs(peer->delay) + peer->rootdelay) / 2 +
peer->rootdispersion + peer->disp +
SQRT(peer->variance) + CLOCK_PHI * (current_time -
peer->update));
}
/*
* peer_xmit - send packet for persistent association.
*/
static void
peer_xmit(
struct peer *peer /* peer structure pointer */
)
{
struct pkt xpkt;
int find_rtt = (peer->cast_flags & MDF_MCAST) &&
peer->hmode != MODE_BROADCAST;
int sendlen;
/*
* Initialize protocol 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 +
LOGTOD(sys_precision)));
xpkt.refid = sys_refid;
HTONL_FP(&sys_reftime, &xpkt.reftime);
HTONL_FP(&peer->org, &xpkt.org);
HTONL_FP(&peer->rec, &xpkt.rec);
/*
* Authenticate the packet if enabled and either configured or
* the previous packet was authenticated. If for some reason the
* key associated with the key identifier is not in the key
* cache, then honk key zero.
*/
sendlen = LEN_PKT_NOMAC;
if (peer->flags & FLAG_AUTHENABLE) {
u_long xkeyid;
l_fp xmt_tx;
/*
* Transmit encrypted packet compensated for the
* encryption delay.
*/
#ifdef MD5
if (peer->flags & FLAG_SKEY) {
/*
* In autokey mode, allocate and initialize a
* key list 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 we
* have to wait until the receive side of the
* socket is bound and the server address
* confirmed.
*/
if (ntohl(peer->dstadr->sin.sin_addr.s_addr) ==
0 &&
ntohl(peer->dstadr->bcast.sin_addr.s_addr) == 0)
peer->keyid = 0;
else {
if (peer->keylist == 0) {
make_keylist(peer);
} else {
authtrust(peer->keylist[peer->keynumber], 0);
if (peer->keynumber == 0)
make_keylist(peer);
else {
peer->keynumber--;
xkeyid = peer->keylist[peer->keynumber];
if (!authistrusted(xkeyid))
make_keylist(peer);
}
}
peer->keyid = peer->keylist[peer->keynumber];
xpkt.keyid1 = htonl(2 * sizeof(u_int32));
xpkt.keyid2 = htonl(sys_private);
sendlen += 2 * sizeof(u_int32);
}
}
#endif /* MD5 */
xkeyid = peer->keyid;
get_systime(&peer->xmt);
L_ADD(&peer->xmt, &sys_authdelay);
HTONL_FP(&peer->xmt, &xpkt.xmt);
sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt,
sendlen);
get_systime(&xmt_tx);
sendpkt(&peer->srcadr, find_rtt ? any_interface :
peer->dstadr, ((peer->cast_flags & MDF_MCAST) &&
!find_rtt) ? ((peer->cast_flags & MDF_ACAST) ? -7 :
peer->ttl) : -7, &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 DEBUG
if (debug)
printf(
"transmit: at %ld to %s mode %d keyid %08lx index %d\n",
current_time, ntoa(&peer->srcadr),
peer->hmode, xkeyid, peer->keynumber);
#endif
} else {
/*
* Transmit non-authenticated packet.
*/
get_systime(&(peer->xmt));
HTONL_FP(&peer->xmt, &xpkt.xmt);
sendpkt(&(peer->srcadr), find_rtt ? any_interface :
peer->dstadr, ((peer->cast_flags & MDF_MCAST) &&
!find_rtt) ? ((peer->cast_flags & MDF_ACAST) ? -7 :
peer->ttl) : -8, &xpkt, sendlen);
peer->sent++;
#ifdef DEBUG
if (debug)
printf("transmit: at %ld to %s mode %d\n",
current_time, ntoa(&peer->srcadr),
peer->hmode);
#endif
}
}
/*
* fast_xmit - Send packet for nonpersistent association.
*/
static void
fast_xmit(
struct recvbuf *rbufp, /* receive packet pointer */
int xmode, /* transmit mode */
u_long xkeyid /* transmit key ID */
)
{
struct pkt xpkt;
struct pkt *rpkt;
int sendlen;
l_fp xmt_ts;
/*
* Initialize transmit packet header fields in the receive
* buffer provided. We leave some fields intact as received.
*/
rpkt = &rbufp->recv_pkt;
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.ppoll = rpkt->ppoll;
xpkt.precision = sys_precision;
xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
xpkt.rootdispersion = HTONS_FP(DTOUFP(sys_rootdispersion +
LOGTOD(sys_precision)));
xpkt.refid = sys_refid;
HTONL_FP(&sys_reftime, &xpkt.reftime);
xpkt.org = rpkt->xmt;
HTONL_FP(&rbufp->recv_time, &xpkt.rec);
sendlen = LEN_PKT_NOMAC;
if (rbufp->recv_length > sendlen) {
l_fp xmt_tx;
/*
* Transmit encrypted packet compensated for the
* encryption delay.
*/
if (xkeyid > NTP_MAXKEY) {
xpkt.keyid1 = htonl(2 * sizeof(u_int32));
xpkt.keyid2 = htonl(sys_private);
sendlen += 2 * sizeof(u_int32);
}
get_systime(&xmt_ts);
L_ADD(&xmt_ts, &sys_authdelay);
HTONL_FP(&xmt_ts, &xpkt.xmt);
sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt,
sendlen);
get_systime(&xmt_tx);
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, -9, &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 to %s mode %d keyid %08lx\n",
current_time, ntoa(&rbufp->recv_srcadr),
xmode, xkeyid);
#endif
} else {
/*
* Transmit non-authenticated packet.
*/
get_systime(&xmt_ts);
HTONL_FP(&xmt_ts, &xpkt.xmt);
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, -10, &xpkt,
sendlen);
#ifdef DEBUG
if (debug)
printf("transmit: at %ld to %s mode %d\n",
current_time, ntoa(&rbufp->recv_srcadr),
xmode);
#endif
}
}
#ifdef MD5
/*
* Compute key list
*/
static void
make_keylist(
struct peer *peer
)
{
int i;
u_long keyid;
u_long ltemp;
/*
* Allocate the key list if necessary.
*/
if (peer->keylist == 0)
peer->keylist = (u_long *)emalloc(sizeof(u_long) *
NTP_MAXSESSION);
/*
* Generate an initial key ID which is unique and greater than
* NTP_MAXKEY.
*/
while (1) {
keyid = (u_long)RANDOM & 0xffffffff;
if (keyid <= NTP_MAXKEY)
continue;
if (authhavekey(keyid))
continue;
break;
}
/*
* Generate up to NTP_MAXSESSION session keys. Stop if the
* next one would not be unique or not a session key ID or if
* it would expire before the next poll.
*/
ltemp = sys_automax;
for (i = 0; i < NTP_MAXSESSION; i++) {
peer->keylist[i] = keyid;
peer->keynumber = i;
keyid = session_key(
ntohl(peer->dstadr->sin.sin_addr.s_addr),
(peer->hmode == MODE_BROADCAST || (peer->flags &
FLAG_MCAST2)) ?
ntohl(peer->dstadr->bcast.sin_addr.s_addr):
ntohl(peer->srcadr.sin_addr.s_addr), keyid, ltemp);
ltemp -= 1 << peer->hpoll;
if (auth_havekey(keyid) || keyid <= NTP_MAXKEY ||
ltemp <= (1 << (peer->hpoll + 1)))
break;
}
}
#endif /* MD5 */
/*
* Find the precision of this particular machine
*/
#define DUSECS 1000000 /* us in a s */
#define HUSECS (1 << 20) /* approx DUSECS for shifting etc */
#define MINSTEP 5 /* minimum clock increment (us) */
#define MAXSTEP 20000 /* maximum clock increment (us) */
#define MINLOOPS 5 /* minimum number of step samples */
/*
* This routine calculates the differences between successive calls to
* gettimeofday(). If a difference is less than zero, the us field
* has rolled over to the next second, so we add a second in us. If
* the difference is greater than zero and less than MINSTEP, the
* clock has been advanced by a small amount to avoid standing still.
* If the clock has advanced by a greater amount, then a timer interrupt
* has occurred and this amount represents the precision of the clock.
* In order to guard against spurious values, which could occur if we
* happen to hit a fat interrupt, we do this for MINLOOPS times and
* keep the minimum value obtained.
*/
int
default_get_precision(void)
{
struct timeval tp;
#if !defined(SYS_WINNT) && !defined(VMS) && !defined(_SEQUENT_)
struct timezone tzp;
#elif defined(VMS) || defined(_SEQUENT_)
struct timezone {
int tz_minuteswest;
int tz_dsttime;
} tzp;
#endif /* defined(VMS) || defined(_SEQUENT_) */
long last;
int i;
long diff;
long val;
long usec;
#ifdef HAVE_GETCLOCK
struct timespec ts;
#endif
#if defined(__FreeBSD__) && __FreeBSD__ >= 3
u_long freq;
size_t j;
/* Try to see if we can find the frequency of of the counter
* which drives our timekeeping
*/
j = sizeof freq;
i = sysctlbyname("kern.timecounter.frequency", &freq, &j , 0,
0);
if (i)
i = sysctlbyname("machdep.tsc_freq", &freq, &j , 0, 0);
if (i)
i = sysctlbyname("machdep.i586_freq", &freq, &j , 0, 0);
if (i)
i = sysctlbyname("machdep.i8254_freq", &freq, &j , 0,
0);
if (!i) {
for (i = 1; freq ; i--)
freq >>= 1;
return (i);
}
#endif
usec = 0;
val = MAXSTEP;
#ifdef HAVE_GETCLOCK
(void) getclock(TIMEOFDAY, &ts);
tp.tv_sec = ts.tv_sec;
tp.tv_usec = ts.tv_nsec / 1000;
#else /* not HAVE_GETCLOCK */
GETTIMEOFDAY(&tp, &tzp);
#endif /* not HAVE_GETCLOCK */
last = tp.tv_usec;
for (i = 0; i < MINLOOPS && usec < HUSECS;) {
#ifdef HAVE_GETCLOCK
(void) getclock(TIMEOFDAY, &ts);
tp.tv_sec = ts.tv_sec;
tp.tv_usec = ts.tv_nsec / 1000;
#else /* not HAVE_GETCLOCK */
GETTIMEOFDAY(&tp, &tzp);
#endif /* not HAVE_GETCLOCK */
diff = tp.tv_usec - last;
last = tp.tv_usec;
if (diff < 0)
diff += DUSECS;
usec += diff;
if (diff > MINSTEP) {
i++;
if (diff < val)
val = diff;
}
}
NLOG(NLOG_SYSINFO)
msyslog(LOG_INFO, "precision = %ld usec", val);
if (usec >= HUSECS)
val = MINSTEP; /* val <= MINSTEP; fast machine */
diff = HUSECS;
for (i = 0; diff > val; i--)
diff >>= 1;
return (i);
}
/*
* init_proto - initialize the protocol module's data
*/
void
init_proto(void)
{
l_fp dummy;
/*
* Fill in the sys_* stuff. Default is don't listen to
* broadcasting, authenticate.
*/
sys_leap = LEAP_NOTINSYNC;
sys_stratum = STRATUM_UNSPEC;
sys_precision = (s_char)default_get_precision();
sys_rootdelay = 0;
sys_rootdispersion = 0;
sys_refid = 0;
L_CLR(&sys_reftime);
sys_peer = 0;
get_systime(&dummy);
sys_bclient = 0;
sys_bdelay = DEFBROADDELAY;
#if defined(DES) || defined(MD5)
sys_authenticate = 1;
#else
sys_authenticate = 0;
#endif
L_CLR(&sys_authdelay);
sys_authdly[0] = sys_authdly[1] = 0;
sys_stattime = 0;
sys_badstratum = 0;
sys_oldversionpkt = 0;
sys_newversionpkt = 0;
sys_badlength = 0;
sys_unknownversion = 0;
sys_processed = 0;
sys_badauth = 0;
sys_manycastserver = 0;
sys_automax = 1 << NTP_AUTOMAX;
/*
* Default these to enable
*/
ntp_enable = 1;
#ifndef KERNEL_FLL_BUG
kern_enable = 1;
#endif
msyslog(LOG_DEBUG, "kern_enable is %d", kern_enable);
stats_control = 1;
/*
* Some system clocks should only be adjusted in 10ms increments.
*/
#if defined RELIANTUNIX_CLOCK
systime_10ms_ticks = 1; /* Reliant UNIX */
#elif defined SCO5_CLOCK
if (sys_precision >= (s_char)-10) /* pre-SCO OpenServer 5.0.6 */
systime_10ms_ticks = 1;
#endif
if (systime_10ms_ticks)
msyslog(LOG_INFO, "using 10ms tick adjustments");
}
/*
* proto_config - configure the protocol module
*/
void
proto_config(
int item,
u_long value,
double dvalue
)
{
/*
* Figure out what he wants to change, then do it
*/
switch (item) {
case PROTO_KERNEL:
/*
* Turn on/off kernel discipline
*/
kern_enable = (int)value;
break;
case PROTO_NTP:
/*
* Turn on/off clock discipline
*/
ntp_enable = (int)value;
break;
case PROTO_MONITOR:
/*
* Turn on/off monitoring
*/
if (value)
mon_start(MON_ON);
else
mon_stop(MON_ON);
break;
case PROTO_FILEGEN:
/*
* Turn on/off statistics
*/
stats_control = (int)value;
break;
case PROTO_BROADCLIENT:
/*
* Turn on/off facility to listen to broadcasts
*/
sys_bclient = (int)value;
if (value)
io_setbclient();
else
io_unsetbclient();
break;
case PROTO_MULTICAST_ADD:
/*
* Add muliticast group address
*/
io_multicast_add(value);
break;
case PROTO_MULTICAST_DEL:
/*
* Delete multicast group address
*/
io_multicast_del(value);
break;
case PROTO_BROADDELAY:
/*
* Set default broadcast delay
*/
sys_bdelay = dvalue;
break;
case PROTO_AUTHENTICATE:
/*
* Specify the use of authenticated data
*/
sys_authenticate = (int)value;
break;
default:
/*
* Log this error
*/
msyslog(LOG_ERR,
"proto_config: illegal item %d, value %ld",
item, value);
break;
}
}
/*
* proto_clr_stats - clear protocol stat counters
*/
void
proto_clr_stats(void)
{
sys_badstratum = 0;
sys_oldversionpkt = 0;
sys_newversionpkt = 0;
sys_unknownversion = 0;
sys_badlength = 0;
sys_processed = 0;
sys_badauth = 0;
sys_stattime = current_time;
sys_limitrejected = 0;
}
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