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freebsd-dev/usr.sbin/xntpd/xntpd/ntp_proto.c
Rodney W. Grimes 709e8f9ae1 Remove trailing whitespace.
1995-05-30 03:57:47 +00:00

2269 lines
56 KiB
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/*
* ntp_proto.c - NTP version 3 protocol machinery
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include "ntpd.h"
#include "ntp_stdlib.h"
#include "ntp_unixtime.h"
/*
* 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 */
s_fp sys_rootdelay; /* distance to current sync source */
u_fp sys_rootdispersion; /* dispersion of system clock */
u_long sys_refid; /* reference source for local clock */
l_fp sys_offset; /* combined offset from clock_select */
u_fp sys_maxd; /* dispersion of selected peer */
l_fp sys_reftime; /* time we were last updated */
l_fp sys_refskew; /* accumulated skew since last update */
struct peer *sys_peer; /* our current peer */
u_char sys_poll; /* log2 of system poll interval */
extern long sys_clock; /* second part of current time */
long sys_lastselect; /* sys_clock at last synch update */
/*
* Nonspecified system state variables.
*/
int sys_bclient; /* we set our time to broadcasts */
s_fp sys_bdelay; /* broadcast client default delay */
int sys_authenticate; /* authenticate time used for syncing */
u_char consensus_leap; /* mitigated leap bits */
u_long sys_authdelay; /* encryption time (l_fp fraction) */
u_char leap_consensus; /* consensus of survivor leap bits */
/*
* 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 toclient count per net */
/*
* Imported from ntp_timer.c
*/
extern u_long current_time;
extern struct event timerqueue[];
/*
* Imported from ntp_io.c
*/
extern struct interface *any_interface;
/*
* Imported from ntp_loopfilter.c
*/
extern int pll_enable;
extern int pps_update;
/*
* Imported from ntp_util.c
*/
extern int stats_control;
/*
* The peer hash table. Imported from ntp_peer.c
*/
extern struct peer *peer_hash[];
extern int peer_hash_count[];
/*
* debug flag
*/
extern int debug;
static void clear_all P((void));
/*
* transmit - Transmit Procedure. See Section 3.4.1 of the
* specification.
*/
void
transmit(peer)
register struct peer *peer;
{
struct pkt xpkt; /* packet to send */
u_long peer_timer;
u_fp precision;
int bool;
/*
* 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.
*/
bool = 0;
if (peer->hmode != MODE_BROADCAST) {
if (peer->hmode != MODE_BCLIENT)
bool = 1;
} else if (sys_peer != 0 && sys_leap != LEAP_NOTINSYNC) {
if (!(sys_peer->refclktype == REFCLK_LOCALCLOCK &&
!(sys_peer->flags & FLAG_PREFER)))
bool = 1;
}
if (bool) {
u_long xkeyid;
int find_rtt = (peer->cast_flags & MDF_MCAST) &&
peer->hmode != MODE_BROADCAST;
/*
* Figure out which keyid to include in the packet
*/
if ((peer->flags & FLAG_AUTHENABLE)
&& (peer->flags & (FLAG_CONFIG|FLAG_AUTHENTIC))
&& authhavekey(peer->keyid)) {
xkeyid = peer->keyid;
} else {
xkeyid = 0;
}
/*
* Make up a packet to send.
*/
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(sys_rootdelay);
precision = FP_SECOND >> -(int)sys_precision;
if (precision == 0)
precision = 1;
xpkt.rootdispersion = HTONS_FP(sys_rootdispersion +
precision + LFPTOFP(&sys_refskew));
xpkt.refid = sys_refid;
HTONL_FP(&sys_reftime, &xpkt.reftime);
HTONL_FP(&peer->org, &xpkt.org);
HTONL_FP(&peer->rec, &xpkt.rec);
/*
* Decide whether to authenticate or not. If so, call
* encrypt() to fill in the rest of the frame. If not,
* just add in the xmt timestamp and send it quick.
*/
if (peer->flags & FLAG_AUTHENABLE) {
int sendlen;
xpkt.keyid = htonl(xkeyid);
auth1crypt(xkeyid, (U_LONG *)&xpkt,
LEN_PKT_NOMAC);
get_systime(&peer->xmt);
L_ADDUF(&peer->xmt, sys_authdelay);
HTONL_FP(&peer->xmt, &xpkt.xmt);
sendlen = auth2crypt(xkeyid, (U_LONG *)&xpkt,
LEN_PKT_NOMAC);
sendpkt(&peer->srcadr, find_rtt ?
any_interface : peer->dstadr,
((peer->cast_flags & MDF_MCAST) && !find_rtt) ?
peer->ttl : -7, &xpkt, sendlen +
LEN_PKT_NOMAC);
#ifdef DEBUG
if (debug > 1)
printf("transmit auth to %s\n",
ntoa(&(peer->srcadr)));
#endif
peer->sent++;
} else {
/*
* Get xmt timestamp, then send it without mac
* field
*/
int find_rtt = (peer->cast_flags & MDF_MCAST) &&
peer->dstadr != any_interface;
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->ttl : -8, &xpkt, LEN_PKT_NOMAC);
#ifdef DEBUG
if (debug > 1)
printf("transmit to %s\n",
ntoa(&(peer->srcadr)));
#endif
peer->sent++;
}
}
if (peer->hmode != MODE_BROADCAST) {
u_char opeer_reach;
/*
* Determine reachability and diddle things if we
* haven't heard from the host for a while. If we are
* about to become unreachable and are a
* broadcast/multicast client, the server has refused to
* boogie in client/server mode, so we switch to
* MODE_BCLIENT anyway and wait for subsequent
* broadcasts.
*/
opeer_reach = peer->reach;
if (opeer_reach & 0x80 && peer->flags & FLAG_MCAST2) {
peer->hmode = MODE_BCLIENT;
}
peer->reach <<= 1;
if (peer->reach == 0) {
if (opeer_reach != 0)
report_event(EVNT_UNREACH, peer);
/*
* Clear this guy out. No need to redo clock
* selection since by now this guy won't be a
* player
*/
if (peer->flags & FLAG_CONFIG) {
if (opeer_reach != 0) {
peer_clear(peer);
peer->timereachable =
current_time;
}
}
/*
* While we have a chance, if our system peer is
* zero or his stratum is greater than the last
* known stratum of this guy, make sure hpoll is
* clamped to the minimum before resetting the
* timer. If the peer has been unreachable for a
* while and we have a system peer who is at
* least his equal, we may want to ramp his
* polling interval up to avoid the useless
* traffic.
*/
if (sys_peer == 0) {
peer->hpoll = peer->minpoll;
peer->unreach = 0;
} else if (sys_peer->stratum > peer->stratum) {
peer->hpoll = peer->minpoll;
peer->unreach = 0;
} else {
if (peer->unreach < 16) {
peer->unreach++;
peer->hpoll = peer->minpoll;
} else if (peer->hpoll < peer->maxpoll) {
peer->hpoll++;
peer->ppoll = peer->hpoll;
}
}
/*
* Update reachability and poll variables
*/
} else if ((opeer_reach & 3) == 0) {
l_fp off;
if (peer->valid > 0)
peer->valid--;
if (peer->hpoll > peer->minpoll)
peer->hpoll--;
L_CLR(&off);
clock_filter(peer, &off, (s_fp)0,
(u_fp)NTP_MAXDISPERSE);
if (peer->flags & FLAG_SYSPEER)
clock_select();
} else {
if (peer->valid < NTP_SHIFT) {
peer->valid++;
} else {
if (peer->hpoll < peer->maxpoll)
peer->hpoll++;
}
}
}
/*
* Finally, adjust the hpoll variable for special conditions. If
* we are a broadcast/multicast client, we use the server poll
* interval if listening for broadcasts and one-eighth this
* interval if in client/server mode. The following clamp
* prevents madness. If this is the system poll, sys_poll
* controls hpoll.
*/
if (peer->flags & FLAG_MCAST2) {
if (peer->hmode == MODE_BCLIENT)
peer->hpoll = peer->ppoll;
else
peer->hpoll = peer->ppoll - 3;
} else if (peer->flags & FLAG_SYSPEER)
peer->hpoll = sys_poll;
if (peer->hpoll < peer->minpoll)
peer->hpoll = peer->minpoll;
/*
* Arrange for our next timeout. hpoll will be less than maxpoll
* for sure.
*/
if (peer->event_timer.next != 0)
/*
* Oops, someone did already.
*/
TIMER_DEQUEUE(&peer->event_timer);
peer_timer = 1 << (int)max((u_char)min(peer->ppoll,
peer->hpoll), peer->minpoll);
peer->event_timer.event_time = current_time + peer_timer;
TIMER_ENQUEUE(timerqueue, &peer->event_timer);
}
/*
* receive - Receive Procedure. See section 3.4.2 in the specification.
*/
void
receive(rbufp)
struct recvbuf *rbufp;
{
register struct peer *peer;
register struct pkt *pkt;
register u_char hismode;
int restrict;
int has_mac;
int trustable;
int is_authentic;
u_long hiskeyid;
struct peer *peer2;
#ifdef DEBUG
if (debug > 1)
printf("receive from %s\n", ntoa(&rbufp->recv_srcadr));
#endif
/*
* Let the monitoring software take a look at this first.
*/
monitor(rbufp);
/*
* Get the restrictions on this guy. If we're to ignore him,
* go no further.
*/
restrict = restrictions(&rbufp->recv_srcadr);
if (restrict & RES_IGNORE)
return;
/*
* Get a pointer to the packet.
*/
pkt = &rbufp->recv_pkt;
/*
* Catch packets whose version number we can't deal with
*/
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;
}
/*
* Catch private mode packets. Dump it if queries not allowed.
*/
if (PKT_MODE(pkt->li_vn_mode) == MODE_PRIVATE) {
if (restrict & RES_NOQUERY)
return;
process_private(rbufp, ((restrict&RES_NOMODIFY) == 0));
return;
}
/*
* Same with control mode packets.
*/
if (PKT_MODE(pkt->li_vn_mode) == MODE_CONTROL) {
if (restrict & RES_NOQUERY)
return;
process_control(rbufp, restrict);
return;
}
/*
* See if we're allowed to serve this guy time. If not, ignore
* him.
*/
if (restrict & 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 & RES_LIMITED) {
extern u_long client_limit;
sys_limitrejected++;
syslog(LOG_NOTICE,
"rejected mode %d request from %s - per net client limit (%d) exceeded",
PKT_MODE(pkt->li_vn_mode),
ntoa(&rbufp->recv_srcadr), client_limit);
return;
}
/*
* Dump anything with a putrid stratum. These will most likely
* come from someone trying to poll us with ntpdc.
*/
if (pkt->stratum > NTP_MAXSTRATUM) {
sys_badstratum++;
return;
}
/*
* 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);
/*
* Check the length for validity, drop the packet if it is
* not as expected. If this is a client mode poll, go no
* further. Send back his time and drop it.
*
* The scheme we use for authentication is this. If we are
* running in non-authenticated mode, we accept both frames
* which are authenticated and frames which aren't, but don't
* authenticate. We do record whether the frame had a mac field
* or not so we know what to do on output.
*
* If we are running in authenticated mode, we only trust frames
* which have authentication attached, which are validated and
* which are using one of our trusted keys. We respond to all
* other pollers without saving any state. If a host we are
* passively peering with changes his key from a trusted one to
* an untrusted one, we immediately unpeer with him, reselect
* the clock and treat him as an unmemorable client (this is
* a small denial-of-service hole I'll have to think about).
* If a similar event occurs with a configured peer we drop the
* frame and hope he'll revert to our key again. If we get a
* frame which can't be authenticated with the given key, we
* drop it. Either we disagree on the keys or someone is trying
* some funny stuff.
*/
/*
* here we assume that any packet with an authenticator is at
* least LEN_PKT_MAC bytes long, which means at least 96 bits
*/
if (rbufp->recv_length >= LEN_PKT_MAC) {
has_mac = rbufp->recv_length - LEN_PKT_NOMAC;
hiskeyid = ntohl(pkt->keyid);
#ifdef DEBUG
if (debug > 2)
printf(
"receive: pkt is %d octets, mac %d octets long, keyid %ld\n",
rbufp->recv_length, has_mac, hiskeyid);
#endif
} else if (rbufp->recv_length == LEN_PKT_NOMAC) {
hiskeyid = 0;
has_mac = 0;
} else {
#ifdef DEBUG
if (debug > 2)
printf("receive: bad length %d %ld\n",
rbufp->recv_length, sizeof(struct pkt));
#endif
sys_badlength++;
return;
}
/*
* Figure out his mode and validate it.
*/
hismode = PKT_MODE(pkt->li_vn_mode);
#ifdef DEBUG
if (debug > 2)
printf("receive: his mode %d\n", hismode);
#endif
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) {
syslog(LOG_ERR, "bad mode %d received from %s",
PKT_MODE(pkt->li_vn_mode),
ntoa(&rbufp->recv_srcadr));
return;
}
}
/*
* If he included a mac field, decrypt it to see if it is
* authentic.
*/
is_authentic = 0;
if (has_mac) {
if (authhavekey(hiskeyid)) {
if (!authistrusted(hiskeyid)) {
sys_badauth++;
#ifdef DEBUG
if (debug > 3)
printf("receive: untrusted keyid\n");
#endif
return;
}
if (authdecrypt(hiskeyid, (U_LONG *)pkt,
LEN_PKT_NOMAC)) {
is_authentic = 1;
#ifdef DEBUG
if (debug > 3)
printf("receive: authdecrypt succeeds\n");
#endif
} else {
sys_badauth++;
#ifdef DEBUG
if (debug > 3)
printf("receive: authdecrypt fails\n");
#endif
}
}
}
/*
* If this is someone we don't remember from a previous
* association, dispatch him now. Either we send something back
* quick, we ignore him, or we allocate some memory for him and
* let him continue.
*/
if (peer == 0) {
int mymode;
mymode = MODE_PASSIVE;
switch(hismode) {
case MODE_ACTIVE:
/*
* See if this guy qualifies as being the least
* bit memorable. If so we keep him around for
* later. If not, send his time quick.
*/
if (restrict & RES_NOPEER) {
fast_xmit(rbufp, (int)hismode,
is_authentic);
return;
}
break;
case MODE_PASSIVE:
case MODE_SERVER:
/*
* These are obvious errors. Ignore.
*/
return;
case MODE_CLIENT:
/*
* Send it back quick and go home.
*/
fast_xmit(rbufp, (int)hismode, is_authentic);
return;
case MODE_BROADCAST:
/*
* Sort of a repeat of the above...
*/
if ((restrict & RES_NOPEER) || !sys_bclient)
return;
mymode = MODE_MCLIENT;
break;
}
/*
* Okay, we're going to keep him around. Allocate him
* some memory.
*/
peer = newpeer(&rbufp->recv_srcadr,
rbufp->dstadr, mymode, PKT_VERSION(pkt->li_vn_mode),
NTP_MINDPOLL, NTP_MAXDPOLL, 0, hiskeyid);
if (peer == 0) {
/*
* The only way this can happen is if the
* source address looks like a reference
* clock. Since this is an illegal address
* this is one of those "can't happen" things.
*/
syslog(LOG_ERR,
"receive() failed to peer with %s, mode %d",
ntoa(&rbufp->recv_srcadr), mymode);
return;
}
}
/*
* Mark the time of reception
*/
peer->timereceived = current_time;
/*
* If the peer isn't configured, set his keyid and authenable
* status based on the packet.
*/
if (!(peer->flags & FLAG_CONFIG)) {
if (has_mac) {
if (!(peer->reach && peer->keyid != hiskeyid)) {
peer->keyid = hiskeyid;
peer->flags |= FLAG_AUTHENABLE;
}
} else {
peer->keyid = 0;
peer->flags &= ~FLAG_AUTHENABLE;
}
}
/*
* If this message was authenticated properly, note this
* in the flags.
*/
if (is_authentic) {
peer->flags |= FLAG_AUTHENTIC;
} else {
/*
* If this guy is authenable, and has been authenticated
* in the past, but just failed the authentic test,
* report the event.
*/
if (peer->flags & FLAG_AUTHENABLE
&& peer->flags & FLAG_AUTHENTIC)
report_event(EVNT_PEERAUTH, peer);
peer->flags &= ~FLAG_AUTHENTIC;
}
/*
* Determine if this guy is basically trustable.
*/
if (restrict & RES_DONTTRUST)
trustable = 0;
else
trustable = 1;
if (sys_authenticate && trustable) {
if (!(peer->flags & FLAG_CONFIG) ||
(peer->flags & FLAG_AUTHENABLE)) {
if (has_mac && is_authentic)
trustable = 1;
else
trustable = 0;
}
}
/*
* Dispose of the packet based on our respective modes. We
* don't drive this with a table, though we probably could.
*/
switch (peer->hmode) {
case MODE_ACTIVE:
case MODE_CLIENT:
/*
* Active mode associations are configured. If the data
* isn't trustable, ignore it and hope this guy
* brightens up. Else accept any data we get and process
* it.
*/
switch (hismode) {
case MODE_ACTIVE:
case MODE_PASSIVE:
case MODE_SERVER:
case MODE_BROADCAST:
process_packet(peer, pkt, &(rbufp->recv_time),
has_mac, trustable);
break;
case MODE_CLIENT:
if (peer->hmode == MODE_ACTIVE)
fast_xmit(rbufp, hismode, is_authentic);
return;
}
break;
case MODE_PASSIVE:
/*
* Passive mode associations are (in the current
* implementation) always dynamic. If we get an invalid
* header, break the connection. I hate doing this since
* it seems like a waste. Oh, well.
*/
switch (hismode) {
case MODE_ACTIVE:
if (process_packet(peer, pkt,
&(rbufp->recv_time),
has_mac, trustable) == 0) {
unpeer(peer);
clock_select();
fast_xmit(rbufp, (int)hismode, is_authentic);
}
break;
case MODE_PASSIVE:
case MODE_SERVER:
case MODE_BROADCAST:
/*
* These are errors. Just ignore the packet.
* If he doesn't straighten himself out this
* association will eventually be disolved.
*/
break;
case MODE_CLIENT:
fast_xmit(rbufp, hismode, is_authentic);
return;
}
break;
case MODE_BCLIENT:
/*
* Broadcast client pseudo-mode. We accept both server
* and broadcast data. Passive mode data is an error.
*/
switch (hismode) {
case MODE_ACTIVE:
/*
* This guy wants to give us real time when
* we've been existing on lousy broadcasts!
* Create a passive mode association and do it
* that way, but keep the old one in case the
* packet turns out to be bad.
*/
peer2 = newpeer(&rbufp->recv_srcadr,
rbufp->dstadr, MODE_PASSIVE,
PKT_VERSION(pkt->li_vn_mode),
NTP_MINDPOLL, NTP_MAXPOLL, 0, hiskeyid);
if (process_packet(peer2, pkt,
&rbufp->recv_time, has_mac, trustable) == 0) {
/*
* Strange situation. We've been
* receiving broadcasts from him which
* we liked, but we don't like his
* active mode stuff. Keep his old peer
* structure and send him some time
* quickly, we'll figure it out later.
*/
unpeer(peer2);
fast_xmit(rbufp, (int)hismode,
is_authentic);
} else
/*
* Drop the old association
*/
unpeer(peer);
break;
case MODE_PASSIVE:
break;
case MODE_SERVER:
case MODE_BROADCAST:
process_packet(peer, pkt, &rbufp->recv_time,
has_mac, trustable);
/*
* We don't test for invalid headers.
* Let him time out.
*/
break;
}
break;
case MODE_MCLIENT:
/*
* This mode is temporary and does not appear outside
* this routine. It lasts only from the time the
* broadcast/multicast is recognized until the
* association is instantiated. Note that we start up in
* client/server mode to initially synchronize the
* clock.
*/
switch (hismode) {
case MODE_BROADCAST:
peer->flags |= FLAG_MCAST1 | FLAG_MCAST2;
peer->hmode = MODE_CLIENT;
process_packet(peer, pkt, &rbufp->recv_time,
has_mac, trustable);
break;
case MODE_SERVER:
case MODE_PASSIVE:
case MODE_ACTIVE:
case MODE_CLIENT:
break;
}
}
}
/*
* process_packet - Packet Procedure, a la Section 3.4.3 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(peer, pkt, recv_ts, has_mac, trustable)
register struct peer *peer;
register struct pkt *pkt;
l_fp *recv_ts;
int has_mac;
int trustable; /* used as "valid header" */
{
l_fp t10, t23;
s_fp di, ei, p_dist, p_disp;
l_fp ci, p_rec, p_xmt, p_org;
int randomize;
u_char ostratum, oreach;
U_LONG temp;
u_fp precision;
sys_processed++;
peer->processed++;
p_dist = NTOHS_FP(pkt->rootdelay);
p_disp = NTOHS_FP(pkt->rootdispersion);
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->flash = 0;
randomize = POLL_RANDOMCHANGE;
/*
* 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 */
randomize = POLL_MAKERANDOM;
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; /* reuse byte-swapped pkt->xmt */
peer->ppoll = pkt->ppoll;
/*
* Call poll_update(). This will either start us, if the
* association is new, or drop the polling interval if the
* association is existing and ppoll has been reduced.
*/
poll_update(peer, peer->hpoll, randomize);
/*
* Test for valid header (tests 5 through 8)
*/
if (trustable == 0) /* test 5 */
peer->flash |= TEST5; /* authentication failed */
temp = ntohl(pkt->reftime.l_ui);
if (PKT_LEAP(pkt->li_vn_mode) == LEAP_NOTINSYNC || /* test 6 */
p_xmt.l_ui < temp || p_xmt.l_ui >= temp + NTP_MAXAGE)
peer->flash |= TEST6; /* peer clock unsynchronized */
if (!(peer->flags & FLAG_CONFIG) && /* test 7 */
(PKT_TO_STRATUM(pkt->stratum) >= NTP_MAXSTRATUM ||
PKT_TO_STRATUM(pkt->stratum) > sys_stratum))
peer->flash |= TEST7; /* peer stratum out of bounds */
if (p_dist >= NTP_MAXDISPERSE /* test 8 */
|| p_dist <= (-NTP_MAXDISPERSE)
|| p_disp >= NTP_MAXDISPERSE)
peer->flash |= TEST8; /* delay/dispersion too big */
/*
* If the packet header is invalid (tests 5 through 8), exit
*/
if (peer->flash & (TEST5 | TEST6 | TEST7 | TEST8)) {
#ifdef DEBUG
if (debug > 1)
printf("invalid packet header %s %02x\n",
ntoa(&peer->srcadr), peer->flash);
#endif
return(0);
}
/*
* Valid header; update our state.
*/
peer->leap = PKT_LEAP(pkt->li_vn_mode);
peer->pmode = PKT_MODE(pkt->li_vn_mode);
if (has_mac)
peer->pkeyid = ntohl(pkt->keyid);
else
peer->pkeyid = 0;
ostratum = peer->stratum;
peer->stratum = PKT_TO_STRATUM(pkt->stratum);
peer->precision = pkt->precision;
peer->rootdelay = p_dist;
peer->rootdispersion = p_disp;
peer->refid = pkt->refid;
NTOHL_FP(&pkt->reftime, &peer->reftime);
oreach = peer->reach;
if (peer->reach == 0) {
peer->timereachable = current_time;
/*
* If this guy was previously unreachable, set his
* polling interval to the minimum and reset the
* unreach counter.
*/
peer->unreach = 0;
peer->hpoll = peer->minpoll;
}
peer->reach |= 1;
/*
* 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;
precision = FP_SECOND >> -(int)sys_precision;
if (precision == 0)
precision = 1;
ei = precision + peer->rec.l_ui - p_org.l_ui;
/*
* If running in a broacast 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 (peer->pmode == MODE_BROADCAST) {
if (peer->flags & FLAG_MCAST1) {
if (peer->hmode == MODE_BCLIENT)
peer->flags &= ~FLAG_MCAST1;
L_SUB(&ci, &peer->offset);
L_NEG(&ci);
peer->estbdelay = LFPTOFP(&ci);
return (1);
}
FPTOLFP(peer->estbdelay, &t10);
L_ADD(&ci, &t10);
di = peer->delay;
} else {
L_ADD(&ci, &t23);
L_RSHIFT(&ci);
L_SUB(&t23, &t10);
di = LFPTOFP(&t23);
}
#ifdef DEBUG
if (debug > 3)
printf("offset: %s, delay %s, error %s\n",
lfptoa(&ci, 6), fptoa(di, 5), fptoa(ei, 5));
#endif
if (di >= NTP_MAXDISPERSE || di <= (-NTP_MAXDISPERSE)
|| ei >= NTP_MAXDISPERSE) /* test 4 */
peer->flash |= TEST4; /* delay/dispersion too big */
/*
* If the packet data is invalid (tests 1 through 4), exit.
*/
if (peer->flash) {
#ifdef DEBUG
if (debug)
printf("invalid packet data %s %02x\n",
ntoa(&peer->srcadr), peer->flash);
#endif
/*
* If there was a reachability change report it even
* though the packet was bogus.
*/
if (oreach == 0)
report_event(EVNT_REACH, peer);
return(1);
}
/*
* This one is valid. Mark it so, give it to clock_filter().
*/
clock_filter(peer, &ci, di, (u_fp)ei);
/*
* If this guy was previously unreachable, report him reachable.
* Note we do this here so that the peer values we return are
* the updated ones.
*/
if (oreach == 0)
report_event(EVNT_REACH, peer);
/*
* Now update the clock. If we have found a system peer and this
* is a broadcast/multicast client, switch to listen mode.
*/
clock_update(peer);
if (sys_peer && peer->flags & FLAG_MCAST2)
peer->hmode = MODE_BCLIENT;
return(1);
}
/*
* clock_update - Clock-update procedure, see section 3.4.5.
*/
void
clock_update(peer)
struct peer *peer;
{
u_char oleap;
u_char ostratum;
s_fp d;
extern u_char leap_mask;
#ifdef DEBUG
if (debug)
printf("clock_update(%s)\n", ntoa(&peer->srcadr));
#endif
record_peer_stats(&peer->srcadr, ctlpeerstatus(peer),
&peer->offset, peer->delay, peer->dispersion);
/*
* Call the clock selection algorithm to see if this update
* causes the peer to change. If this is not the system peer,
* quit now.
*/
clock_select();
if (peer != sys_peer)
return;
/*
* Update the system state. This updates the system stratum,
* leap bits, root delay, root dispersion, reference ID and
* reference time. We also update select dispersion and max
* frequency error.
*/
oleap = sys_leap;
ostratum = sys_stratum;
sys_stratum = peer->stratum + 1;
if (sys_stratum == 1)
sys_refid = peer->refid;
else
sys_refid = peer->srcadr.sin_addr.s_addr;
sys_reftime = peer->rec;
d = peer->delay;
if (d < 0)
d = -d;
sys_rootdelay = peer->rootdelay + d;
d = peer->soffset;
if (d < 0)
d = -d;
d += peer->dispersion + peer->selectdisp;
if (!peer->flags & FLAG_REFCLOCK && d < NTP_MINDISPERSE)
d = NTP_MINDISPERSE;
sys_rootdispersion = peer->rootdispersion + d;
/*
* Reset/adjust the system clock. Watch for timewarps here.
*/
switch (local_clock(&sys_offset, peer)) {
case -1:
/*
* Clock is too screwed up. Just exit for now.
*/
report_event(EVNT_SYSFAULT, (struct peer *)0);
exit(1);
/*NOTREACHED*/
case 0:
/*
* Clock was slewed. Continue on normally.
*/
sys_leap = leap_consensus & leap_mask;
L_CLR(&sys_refskew);
break;
case 1:
/*
* Clock was stepped. Clear filter registers
* of all peers.
*/
clear_all();
leap_process(); /* reset the leap interrupt */
sys_leap = LEAP_NOTINSYNC;
sys_refskew.l_i = NTP_MAXSKEW; sys_refskew.l_f = 0;
report_event(EVNT_CLOCKRESET, (struct peer *)0);
break;
}
sys_maxd = peer->dispersion + peer->selectdisp;
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 3.4.8 of the
* spec.
*/
void
poll_update(peer, new_hpoll, randomize)
struct peer *peer;
unsigned int new_hpoll;
int randomize;
{
register struct event *evp;
register u_long new_timer;
u_char newpoll, oldpoll;
#ifdef DEBUG
if (debug > 1)
printf("poll_update(%s, %d, %d)\n", ntoa(&peer->srcadr),
new_hpoll, randomize);
#endif
/*
* Catch reference clocks here. The polling interval for a
* reference clock is fixed and needn't be maintained by us.
*/
if (peer->flags & FLAG_REFCLOCK || peer->hmode ==
MODE_BROADCAST)
return;
/*
* This routine * will randomly perturb the new peer.timer if
* requested, to try to prevent synchronization with the remote
* peer from occuring. There are three options, based on the
* value of randomize:
*
* POLL_NOTRANDOM - essentially the spec algorithm. If
* peer.timer is greater than the new polling interval,
* drop it to the new interval.
*
* POLL_RANDOMCHANGE - make changes randomly. If peer.timer
* must be changed, based on the comparison about, randomly
* perturb the new value of peer.timer.
*
* POLL_MAKERANDOM - make next interval random. Calculate
* a randomly perturbed poll interval. If this value is
* less that peer.timer, update peer.timer.
*/
oldpoll = peer->hpoll;
if (peer->hmode == MODE_BCLIENT)
peer->hpoll = peer->ppoll;
else if ((peer->flags & FLAG_SYSPEER) && new_hpoll > sys_poll)
peer->hpoll = max(peer->minpoll, sys_poll);
else {
if (new_hpoll > peer->maxpoll)
peer->hpoll = peer->maxpoll;
else if (new_hpoll < peer->minpoll)
peer->hpoll = peer->minpoll;
else
peer->hpoll = new_hpoll;
}
/* hpoll <= maxpoll for sure */
newpoll = max((u_char)min(peer->ppoll, peer->hpoll),
peer->minpoll);
if (randomize == POLL_MAKERANDOM || (randomize ==
POLL_RANDOMCHANGE && newpoll != oldpoll))
new_timer = (1 << (newpoll - 1))
+ ranp2(newpoll - 1) + current_time;
else
new_timer = (1 << newpoll) + current_time;
evp = &(peer->event_timer);
if (evp->next == 0 || evp->event_time > new_timer) {
TIMER_DEQUEUE(evp);
evp->event_time = new_timer;
TIMER_ENQUEUE(timerqueue, evp);
}
}
/*
* clear_all - clear all peer filter registers. This is done after
* a step change in the time.
*/
static void
clear_all()
{
register int i;
register struct peer *peer;
for (i = 0; i < HASH_SIZE; i++)
for (peer = peer_hash[i]; peer != 0; peer = peer->next) {
peer_clear(peer);
}
/*
* Clear sys_peer. We'll sync to one later.
*/
sys_peer = 0;
sys_stratum = STRATUM_UNSPEC;
}
/*
* clear - clear peer filter registers. See Section 3.4.7 of the spec.
*/
void
peer_clear(peer)
register struct peer *peer;
{
register int i;
#ifdef DEBUG
if (debug)
printf("clear(%s)\n", ntoa(&peer->srcadr));
#endif
memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO);
peer->hpoll = peer->minpoll;
peer->dispersion = NTP_MAXDISPERSE;
for (i = 0; i < NTP_SHIFT; i++)
peer->filter_error[i] = NTP_MAXDISPERSE;
poll_update(peer, peer->minpoll, POLL_RANDOMCHANGE);
clock_select();
/*
* Clear out the selection counters
*/
peer->candidate = 0;
peer->select = 0;
peer->correct = 0;
peer->was_sane = 0;
/*
* 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.
*/
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(peer, sample_offset, sample_delay, sample_error)
register struct peer *peer;
l_fp *sample_offset;
s_fp sample_delay;
u_fp sample_error;
{
register int i, j, k, n;
register u_char *ord;
s_fp distance[NTP_SHIFT];
long skew, skewmax;
#ifdef DEBUG
if (debug)
printf("clock_filter(%s, %s, %s, %s)\n",
ntoa(&peer->srcadr), lfptoa(sample_offset, 6),
fptoa(sample_delay, 5), ufptoa(sample_error, 5));
#endif
/*
* Update sample errors and calculate distances. Also initialize
* sort index vector. We know NTP_SKEWFACTOR == 16
*/
skew = sys_clock - peer->update;
peer->update = sys_clock;
ord = peer->filter_order;
j = peer->filter_nextpt;
for (i = 0; i < NTP_SHIFT; i++) {
peer->filter_error[j] += (u_fp)skew;
if (peer->filter_error[j] > NTP_MAXDISPERSE)
peer->filter_error[j] = NTP_MAXDISPERSE;
distance[i] = peer->filter_error[j] +
(peer->filter_delay[j] >> 1);
ord[i] = j;
if (--j < 0)
j += NTP_SHIFT;
}
/*
* Insert the new sample at the beginning of the register.
*/
peer->filter_delay[peer->filter_nextpt] = sample_delay;
peer->filter_offset[peer->filter_nextpt] = *sample_offset;
peer->filter_soffset[peer->filter_nextpt] =
LFPTOFP(sample_offset);
peer->filter_error[peer->filter_nextpt] = sample_error;
distance[0] = sample_error + (sample_delay >> 1);
/*
* Sort the samples in the register by distance. The winning
* sample will be in ord[0]. Sort the samples only if the
* samples are not too old and the delay is meaningful.
*/
skewmax = 0;
for (n = 0; n < NTP_SHIFT && sample_delay; n++) {
for (j = 0; j < n && skewmax <
CLOCK_MAXSEC; j++) {
if (distance[j] > distance[n]) {
s_fp ftmp;
ftmp = distance[n];
k = ord[n];
distance[n] = distance[j];
ord[n] = ord[j];
distance[j] = ftmp;
ord[j] = k;
}
}
skewmax += (1 << peer->hpoll);
}
peer->filter_nextpt++;
if (peer->filter_nextpt >= NTP_SHIFT)
peer->filter_nextpt = 0;
/*
* We compute the dispersion as per the spec. Note that, to make
* things simple, both the l_fp and s_fp offsets are retained
* and that the s_fp could be nonsense if the l_fp is greater
* than about 32000 s. However, the sanity checks in
* ntp_loopfilter() require the l_fp offset to be less than 1000
* s anyway, so not to worry.
*/
if (peer->filter_error[ord[0]] >= NTP_MAXDISPERSE) {
peer->dispersion = NTP_MAXDISPERSE;
} else {
s_fp d;
u_fp y;
peer->delay = peer->filter_delay[ord[0]];
peer->offset = peer->filter_offset[ord[0]];
peer->soffset = LFPTOFP(&peer->offset);
peer->dispersion = peer->filter_error[ord[0]];
y = 0;
for (i = NTP_SHIFT - 1; i > 0; i--) {
if (peer->filter_error[ord[i]] >=
NTP_MAXDISPERSE)
d = NTP_MAXDISPERSE;
else {
d = peer->filter_soffset[ord[i]] -
peer->filter_soffset[ord[0]];
if (d < 0)
d = -d;
if (d > NTP_MAXDISPERSE)
d = NTP_MAXDISPERSE;
}
/*
* XXX This *knows* NTP_FILTER is 1/2
*/
y = ((u_fp)d + y) >> 1;
}
peer->dispersion += y;
/*
* Calculate synchronization distance backdated to
* sys_lastselect (clock_select will fix it). We know
* NTP_SKEWFACTOR == 16.
*/
d = peer->delay;
if (d < 0)
d = -d;
d += peer->rootdelay;
peer->synch = (d >> 1) + peer->rootdispersion +
peer->dispersion - (sys_clock - sys_lastselect);
}
}
/*
* clock_select - find the pick-of-the-litter clock
*/
void
clock_select()
{
register struct peer *peer;
register int i;
register int nlist, nl3;
register s_fp d, e;
register int j;
register int n;
register int allow, found, k;
s_fp low = 0x7fffffff;
s_fp high = -0x7ffffff;
u_fp 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;
static int *index;
static struct peer **peer_list;
static int endpoint_size = 0, index_size = 0, peer_list_size = 0;
#ifdef DEBUG
if (debug > 1)
printf("clock_select()\n");
#endif
/*
* Initizialize. If a prefer peer does not survive this thing,
* the pps_update switch will remain zero.
*/
pps_update = 0;
nlist = 0;
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 NTP_MAXLIST peers which
* are most likely to succeed. We run through the list
* doing the sanity checks and trying to insert anyone who
* looks okay. We are at all times aware that we should
* only keep samples from the top two strata and we only need
* NTP_MAXLIST of them.
*/
nlist = nl3 = 0; /* none yet */
for (n = 0; n < HASH_SIZE; n++) {
for (peer = peer_hash[n]; peer != 0; peer = peer->next) {
/*
* Clear peer selection stats
*/
peer->was_sane = 0;
peer->correct = 0;
peer->candidate = 0;
peer->select = 0;
peer->flags &= ~FLAG_SYSPEER;
/*
* Update synch distance (NTP_SKEWFACTOR == 16).
* Note synch distance check instead of spec
* dispersion check. Naughty.
*/
peer->synch += (sys_clock - sys_lastselect);
if (peer->reach == 0)
continue; /* unreachable */
if (peer->stratum > 1 && peer->refid ==
peer->dstadr->sin.sin_addr.s_addr)
continue; /* sync loop */
if (peer->stratum >= NTP_MAXSTRATUM ||
peer->stratum > sys_stratum)
continue; /* bad stratum */
if (peer->dispersion >= NTP_MAXDISTANCE) {
peer->seldisptoolarge++;
continue; /* too noisy or broken */
}
if (peer->org.l_ui < peer->reftime.l_ui) {
peer->selbroken++;
continue; /* very broken host */
}
/*
* 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) {
typelocal = peer;
if (!(peer->flags & FLAG_PREFER))
continue; /* no local clock */
}
if (peer->refclktype == REFCLK_NIST_ACTS) {
typeacts = peer;
if (!(peer->flags & FLAG_PREFER))
continue; /* no acts */
}
/*
* If we get this far, we assume the peer is
* acceptable.
*/
peer->was_sane = 1;
peer_list[nlist++] = peer;
/*
* Insert each interval endpoint on the sorted
* list.
*/
e = peer->soffset + peer->synch; /* Upper end */
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 -= peer->synch; /* 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 -= peer->synch; /* 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;
}
}
sys_lastselect = sys_clock;
#ifdef DEBUG
if (debug > 2)
for (i = 0; i < nl3; i++)
printf("select: endpoint %2d %s\n",
endpoint[index[i]].type,
fptoa(endpoint[index[i]].val, 6));
#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->was_sane = 1;
peer_list[0] = typeacts;
nlist = 1;
} else if (typelocal != 0) {
typelocal->was_sane = 1;
peer_list[0] = typelocal;
nlist = 1;
} else {
if (sys_peer != 0)
report_event(EVNT_PEERSTCHG,
(struct peer *)0);
sys_peer = 0;
sys_stratum = STRATUM_UNSPEC;
return;
}
}
#ifdef DEBUG
if (debug > 2)
printf("select: low %s high %s\n", fptoa(low, 6),
fptoa(high, 6));
#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 && (peer->soffset < low || high <
peer->soffset))
continue;
peer->correct = 1;
d = peer->synch + ((u_long)peer->stratum <<
NTP_DISPFACTOR);
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 > 2)
for (i = 0; i < nlist; i++)
printf("select: candidate %s cdist %s\n",
ntoa(&peer_list[i]->srcadr),
fptoa(synch[i], 6));
#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 preferred peer.
*/
for (i = 0; i < nlist; i++) {
peer = peer_list[i];
peer->candidate = i + 1;
error[i] = peer_list[i]->rootdispersion +
peer_list[i]->dispersion +
(sys_clock - peer_list[i]->update);
}
while (1) {
u_fp maxd = 0;
e = error[0];
for (k = i = nlist - 1; i >= 0; i--) {
u_fp sdisp = 0;
for (j = nlist - 1; j > 0; j--) {
d = peer_list[i]->soffset
- peer_list[j]->soffset;
if (d < 0)
d = -d;
sdisp += d;
sdisp = ((sdisp >> 1) + sdisp) >> 1;
}
peer_list[i]->selectdisp = sdisp;
if (sdisp > maxd) {
maxd = sdisp;
k = i;
}
if (error[i] < e)
e = error[i];
}
if (nlist <= NTP_MINCLOCK || maxd <= e ||
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: survivor %s offset %s, cdist %s\n",
ntoa(&peer_list[i]->srcadr),
lfptoa(&peer_list[i]->offset, 6),
fptoa(synch[i], 5));
}
#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]->select = i + 1;
peer_list[i]->flags |= FLAG_SYSPEER;
poll_update(peer_list[i], peer_list[i]->hpoll,
POLL_RANDOMCHANGE);
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 (typeprefer->soffset >= -CLOCK_MAX_FP &&
typeprefer->soffset < CLOCK_MAX_FP)
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 acts
* peers (type REFCLK_NIST_ATOM 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 == typelocal || typeprefer ==
typeacts || !typepps)) {
sys_peer = typeprefer;
sys_peer->selectdisp = 0;
sys_offset = sys_peer->offset;
#ifdef DEBUG
if (debug)
printf("select: prefer offset %s\n",
lfptoa(&sys_offset, 6));
#endif
} else if (typepps) {
sys_peer = typepps;
sys_peer->selectdisp = 0;
sys_offset = sys_peer->offset;
#ifdef DEBUG
if (debug)
printf("select: pps offset %s\n",
lfptoa(&sys_offset, 6));
#endif
} else {
if (!typesystem)
sys_peer = peer_list[0];
clock_combine(peer_list, nlist);
#ifdef DEBUG
if (debug)
printf("select: combine offset %s\n",
lfptoa(&sys_offset, 6));
#endif
}
/*
* If we got a new system peer from all of this, report the
* event and clamp the system poll interval.
*/
if (osys_peer != sys_peer) {
sys_poll = sys_peer->minpoll;
report_event(EVNT_PEERSTCHG, (struct peer *)0);
}
}
/*
* clock_combine - combine offsets from selected peers
*
* Note: this routine uses only those peers at the lowest stratum.
* Strictly speaking, this is at variance with the spec.
*/
void
clock_combine(peers, npeers)
struct peer **peers;
int npeers;
{
register int i, j, k;
register u_fp a, b, d;
u_fp synch[NTP_MAXCLOCK];
l_fp coffset[NTP_MAXCLOCK];
l_fp diff;
/*
* Sort the offsets by synch distance.
*/
k = 0;
for (i = 0; i < npeers; i++) {
if (peers[i]->stratum > sys_peer->stratum)
continue;
d = peers[i]->synch;
for (j = k; j > 0; j--) {
if (synch[j - 1] <= d)
break;
synch[j] = synch[j - 1];
coffset[j] = coffset[j - 1];
}
synch[j] = d;
coffset[j] = peers[i]->offset;
k++;
}
/*
* Succesively combine the two offsets with the highest
* distance and enter the result into the sorted list.
*/
for (i = k - 2; i >= 0; i--) {
/*
* The possible weights for the most distant offset
* are 1/2, 1/4, 1/8 and zero. We combine the synch
* distances as if they were variances of the offsets;
* the given weights allow us to stay within 16/15 of
* the optimum combined variance at each step, and
* within 8/7 on any series.
*
* The breakeven points for the weigths are found
* where the smaller distance is 3/8, 3/16 and 1/16
* of the sum, respectively.
*/
d = synch[i];
a = (d + synch[i + 1]) >> 2; /* (d1+d2)/4 */
b = a>>1; /* (d1+d2)/8 */
if (d <= (b>>1)) /* d1 <= (d1+d2)/16 */
/*
* Below 1/16, no combination is done,
* we just drop the distant offset.
*/
continue;
/*
* The offsets are combined by shifting their
* difference the appropriate number of times and
* adding it back in.
*/
diff = coffset[i + 1];
L_SUB(&diff, &coffset[i]);
L_RSHIFT(&diff);
if (d >= a + b) { /* d1 >= 3(d1+d2)/8 */
/*
* Above 3/8, the weight is 1/2, and the
* combined distance is (d1+d2)/4
*/
d = a;
} else {
a >>= 2; /* (d1+d2)/16 */
L_RSHIFT(&diff);
if (d >= a + b) { /* d1 >= 3(d1+d2)/16 */
/*
* Between 3/16 and 3/8, the weight
* is 1/4, and the combined distance
* is (9d1+d2)/16 = d1/2 + (d1+d2)/16
*/
d = (d>>1) + a;
} else {
/*
* Between 1/16 and 3/16, the weight
* is 1/8, and the combined distance
* is (49d1+d2)/64 = 3d1/4+(d1+d2)/64
* (We know d > a, so the shift is safe).
*/
L_RSHIFT(&diff);
d -= (d - a)>>2;
}
}
/*
* Now we can make the combined offset and insert it
* in the list.
*/
L_ADD(&diff, &coffset[i]);
for (j = i; j > 0; j--) {
if (d >= synch[j - 1])
break;
synch[j] = synch[j - 1];
coffset[j] = coffset[j - 1];
}
synch[j] = d;
coffset[j] = diff;
}
/*
* The result is put where clock_update() can find it.
*/
sys_offset = coffset[0];
}
/*
* fast_xmit - fast path send for stateless (non-)associations
*/
void
fast_xmit(rbufp, rmode, authentic)
struct recvbuf *rbufp;
int rmode;
int authentic;
{
struct pkt xpkt;
register struct pkt *rpkt;
u_char xmode;
u_short xkey = 0;
int docrypt = 0;
l_fp xmt_ts;
u_fp precision;
#ifdef DEBUG
if (debug > 1)
printf("fast_xmit(%s, %d)\n", ntoa(&rbufp->recv_srcadr), rmode);
#endif
/*
* Make up new packet and send it quick
*/
rpkt = &rbufp->recv_pkt;
if (rmode == MODE_ACTIVE)
xmode = MODE_PASSIVE;
else
xmode = MODE_SERVER;
if (rbufp->recv_length >= LEN_PKT_MAC) {
docrypt = rbufp->recv_length - LEN_PKT_NOMAC;
if (authentic)
xkey = ntohl(rpkt->keyid);
}
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 = max(NTP_MINPOLL, rpkt->ppoll);
xpkt.precision = sys_precision;
xpkt.rootdelay = HTONS_FP(sys_rootdelay);
precision = FP_SECOND >> -(int)sys_precision;
if (precision == 0)
precision = 1;
xpkt.rootdispersion = HTONS_FP(sys_rootdispersion +
precision + LFPTOFP(&sys_refskew));
xpkt.refid = sys_refid;
HTONL_FP(&sys_reftime, &xpkt.reftime);
xpkt.org = rpkt->xmt;
HTONL_FP(&rbufp->recv_time, &xpkt.rec);
/*
* If we are encrypting, do it. Else don't. Easy.
*/
if (docrypt) {
int maclen;
xpkt.keyid = htonl(xkey);
auth1crypt(xkey, (U_LONG *)&xpkt, LEN_PKT_NOMAC);
get_systime(&xmt_ts);
L_ADDUF(&xmt_ts, sys_authdelay);
HTONL_FP(&xmt_ts, &xpkt.xmt);
maclen = auth2crypt(xkey, (U_LONG *)&xpkt, LEN_PKT_NOMAC);
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, -9, &xpkt,
LEN_PKT_NOMAC + maclen);
} else {
/*
* Get xmt timestamp, then send it without mac field
*/
get_systime(&xmt_ts);
HTONL_FP(&xmt_ts, &xpkt.xmt);
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, -10, &xpkt,
LEN_PKT_NOMAC);
}
}
/*
* 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 (ys) */
#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()
{
struct timeval tp;
struct timezone tzp;
long last;
int i;
long diff;
long val;
long usec;
usec = 0;
val = MAXSTEP;
GETTIMEOFDAY(&tp, &tzp);
last = tp.tv_usec;
for (i = 0; i < MINLOOPS && usec < HUSECS;) {
GETTIMEOFDAY(&tp, &tzp);
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;
}
}
syslog(LOG_INFO, "precision = %d 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()
{
l_fp dummy;
/*
* Fill in the sys_* stuff. Default is don't listen to
* broadcasting, don't 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_refskew.l_i = NTP_MAXSKEW; sys_refskew.l_f = 0;
sys_peer = 0;
sys_poll = NTP_MINPOLL;
get_systime(&dummy);
sys_lastselect = sys_clock;
sys_bclient = 0;
sys_bdelay = DEFBROADDELAY;
sys_authenticate = 0;
sys_authdelay = DEFAUTHDELAY;
sys_stattime = 0;
sys_badstratum = 0;
sys_oldversionpkt = 0;
sys_newversionpkt = 0;
sys_badlength = 0;
sys_unknownversion = 0;
sys_processed = 0;
sys_badauth = 0;
/*
* Default these to enable
*/
pll_enable = 1;
stats_control = 1;
}
/*
* proto_config - configure the protocol module
*/
void
proto_config(item, value)
int item;
u_long value;
{
/*
* Figure out what he wants to change, then do it
*/
switch (item) {
case PROTO_PLL:
/*
* Turn on/off pll clock correction
*/
pll_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
*/
sys_bclient = 1;
io_multicast_add(value);
break;
case PROTO_MULTICAST_DEL:
/*
* Delete multicast group address
*/
sys_bclient = 1;
io_multicast_del(value);
break;
case PROTO_PRECISION:
/*
* Set system precision
*/
sys_precision = (s_char)value;
break;
case PROTO_BROADDELAY:
/*
* Set default broadcast delay (s_fp)
*/
if (sys_bdelay < 0)
sys_bdelay = -(-value >> 16);
else
sys_bdelay = value >> 16;
break;
case PROTO_AUTHENTICATE:
/*
* Specify the use of authenticated data
*/
sys_authenticate = (int)value;
break;
case PROTO_AUTHDELAY:
/*
* Set authentication delay (l_fp fraction)
*/
sys_authdelay = value;
break;
default:
/*
* Log this error
*/
syslog(LOG_ERR, "proto_config: illegal item %d, value %ld",
item, value);
break;
}
}
/*
* proto_clr_stats - clear protocol stat counters
*/
void
proto_clr_stats()
{
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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