/*
* ntp_proto.c - NTP version 4 protocol machinery
*
* ATTENTION: Get approval from Dave Mills on all changes to this file!
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "ntpd.h"
#include "ntp_stdlib.h"
#include "ntp_unixtime.h"
#include "ntp_control.h"
#include "ntp_string.h"
#include <stdio.h>
#ifdef HAVE_LIBSCF_H
#include <libscf.h>
#include <unistd.h>
#endif /* HAVE_LIBSCF_H */
#if defined(VMS) && defined(VMS_LOCALUNIT) /*wjm*/
#include "ntp_refclock.h"
#endif
/*
* This macro defines the authentication state. If x is 1 authentication
* is required; othewise it is optional.
*/
#define AUTH(x, y) ((x) ? (y) == AUTH_OK : (y) == AUTH_OK || \
(y) == AUTH_NONE)
#define AUTH_NONE 0 /* authentication not required */
#define AUTH_OK 1 /* authentication OK */
#define AUTH_ERROR 2 /* authentication error */
#define AUTH_CRYPTO 3 /* crypto_NAK */
/*
* traffic shaping parameters
*/
#define NTP_IBURST 6 /* packets in iburst */
#define RESP_DELAY 1 /* refclock burst delay (s) */
/*
* System variables are declared here. Unless specified otherwise, all
* times are in seconds.
*/
u_char sys_leap; /* system leap indicator */
u_char sys_stratum; /* system stratum */
s_char sys_precision; /* local clock precision (log2 s) */
double sys_rootdelay; /* roundtrip delay to primary source */
double sys_rootdisp; /* dispersion to primary source */
u_int32 sys_refid; /* reference id (network byte order) */
l_fp sys_reftime; /* last update time */
struct peer *sys_peer; /* current peer */
/*
* Rate controls. Leaky buckets are used to throttle the packet
* transmission rates in order to protect busy servers such as at NIST
* and USNO. There is a counter for each association and another for KoD
* packets. The association counter decrements each second, but not
* below zero. Each time a packet is sent the counter is incremented by
* a configurable value representing the average interval between
* packets. A packet is delayed as long as the counter is greater than
* zero. Note this does not affect the time value computations.
*/
/*
* Nonspecified system state variables
*/
int sys_bclient; /* broadcast client enable */
double sys_bdelay; /* broadcast client default delay */
int sys_authenticate; /* requre authentication for config */
l_fp sys_authdelay; /* authentication delay */
double sys_offset; /* current local clock offset */
double sys_mindisp = MINDISPERSE; /* minimum distance (s) */
double sys_maxdist = MAXDISTANCE; /* selection threshold */
double sys_jitter; /* system jitter */
u_long sys_epoch; /* last clock update time */
static double sys_clockhop; /* clockhop threshold */
int leap_tai; /* TAI at next next leap */
u_long leap_sec; /* next scheduled leap from file */
u_long leap_peers; /* next scheduled leap from peers */
u_long leap_expire; /* leap information expiration */
static int leap_vote; /* leap consensus */
keyid_t sys_private; /* private value for session seed */
int sys_manycastserver; /* respond to manycast client pkts */
int peer_ntpdate; /* active peers in ntpdate mode */
int sys_survivors; /* truest of the truechimers */
/*
* TOS and multicast mapping stuff
*/
int sys_floor = 0; /* cluster stratum floor */
int sys_ceiling = STRATUM_UNSPEC; /* cluster stratum ceiling */
int sys_minsane = 1; /* minimum candidates */
int sys_minclock = NTP_MINCLOCK; /* minimum candidates */
int sys_maxclock = NTP_MAXCLOCK; /* maximum candidates */
int sys_cohort = 0; /* cohort switch */
int sys_orphan = STRATUM_UNSPEC + 1; /* orphan stratum */
int sys_beacon = BEACON; /* manycast beacon interval */
int sys_ttlmax; /* max ttl mapping vector index */
u_char sys_ttl[MAX_TTL]; /* ttl mapping vector */
/*
* Statistics counters - first the good, then the bad
*/
u_long sys_stattime; /* elapsed time */
u_long sys_received; /* packets received */
u_long sys_processed; /* packets for this host */
u_long sys_newversion; /* current version */
u_long sys_oldversion; /* old version */
u_long sys_restricted; /* access denied */
u_long sys_badlength; /* bad length or format */
u_long sys_badauth; /* bad authentication */
u_long sys_declined; /* declined */
u_long sys_limitrejected; /* rate exceeded */
u_long sys_kodsent; /* KoD sent */
static double root_distance (struct peer *);
static void clock_combine (struct peer **, int);
static void peer_xmit (struct peer *);
static void fast_xmit (struct recvbuf *, int, keyid_t,
int);
static void clock_update (struct peer *);
static int default_get_precision (void);
static int local_refid (struct peer *);
static int peer_unfit (struct peer *);
/*
* transmit - transmit procedure called by poll timeout
*/
void
transmit(
struct peer *peer /* peer structure pointer */
)
{
int hpoll;
/*
* The polling state machine. There are two kinds of machines,
* those that never expect a reply (broadcast and manycast
* server modes) and those that do (all other modes). The dance
* is intricate...
*/
hpoll = peer->hpoll;
/*
* In broadcast mode the poll interval is never changed from
* minpoll.
*/
if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) {
peer->outdate = current_time;
if (sys_leap != LEAP_NOTINSYNC)
peer_xmit(peer);
poll_update(peer, hpoll);
return;
}
/*
* In manycast mode we start with unity ttl. The ttl is
* increased by one for each poll until either sys_maxclock
* servers have been found or the maximum ttl is reached. When
* sys_maxclock servers are found we stop polling until one or
* more servers have timed out or until less than minpoll
* associations turn up. In this case additional better servers
* are dragged in and preempt the existing ones.
*/
if (peer->cast_flags & MDF_ACAST) {
peer->outdate = current_time;
if (peer->unreach > sys_beacon) {
peer->unreach = 0;
peer->ttl = 0;
peer_xmit(peer);
} else if (sys_survivors < sys_minclock ||
peer_associations < sys_maxclock) {
if (peer->ttl < sys_ttlmax)
peer->ttl++;
peer_xmit(peer);
}
peer->unreach++;
poll_update(peer, hpoll);
return;
}
/*
* In unicast modes the dance is much more intricate. It is
* desigmed to back off whenever possible to minimize network
* traffic.
*/
if (peer->burst == 0) {
u_char oreach;
/*
* Update the reachability status. If not heard for
* three consecutive polls, stuff infinity in the clock
* filter.
*/
oreach = peer->reach;
peer->outdate = current_time;
peer->unreach++;
peer->reach <<= 1;
if (!(peer->reach & 0x0f))
clock_filter(peer, 0., 0., MAXDISPERSE);
if (!peer->reach) {
/*
* Here the peer is unreachable. If it was
* previously reachable raise a trap. Send a
* burst if enabled.
*/
if (oreach)
report_event(PEVNT_UNREACH, peer, NULL);
if ((peer->flags & FLAG_IBURST) &&
peer->retry == 0)
peer->retry = NTP_RETRY;
} else {
/*
* Here the peer is reachable. Send a burst if
* enabled and the peer is fit.
*/
hpoll = sys_poll;
if (!(peer->flags & FLAG_PREEMPT &&
peer->hmode == MODE_CLIENT))
peer->unreach = 0;
if ((peer->flags & FLAG_BURST) && peer->retry ==
0 && !peer_unfit(peer))
peer->retry = NTP_RETRY;
}
/*
* Watch for timeout. If preemptable, toss the rascal;
* otherwise, bump the poll interval. Note the
* poll_update() routine will clamp it to maxpoll.
*/
if (peer->unreach >= NTP_UNREACH) {
hpoll++;
if (peer->flags & FLAG_PREEMPT) {
report_event(PEVNT_RESTART, peer,
"timeout");
if (peer->hmode != MODE_CLIENT) {
peer_clear(peer, "TIME");
unpeer(peer);
return;
}
if (peer_associations > sys_maxclock &&
score_all(peer)) {
peer_clear(peer, "TIME");
unpeer(peer);
return;
}
}
}
} else {
peer->burst--;
if (peer->burst == 0) {
/*
* If ntpdate mode and the clock has not been
* set and all peers have completed the burst,
* we declare a successful failure.
*/
if (mode_ntpdate) {
peer_ntpdate--;
if (peer_ntpdate == 0) {
msyslog(LOG_NOTICE,
"ntpd: no servers found");
printf(
"ntpd: no servers found\n");
exit (0);
}
}
}
}
if (peer->retry > 0)
peer->retry--;
/*
* Do not transmit if in broadcast client mode.
*/
if (peer->hmode != MODE_BCLIENT)
peer_xmit(peer);
poll_update(peer, hpoll);
}
/*
* receive - receive procedure called for each packet received
*/
void
receive(
struct recvbuf *rbufp
)
{
register struct peer *peer; /* peer structure pointer */
register struct pkt *pkt; /* receive packet pointer */
int hisversion; /* packet version */
int hisleap; /* packet leap indicator */
int hismode; /* packet mode */
int hisstratum; /* packet stratum */
int restrict_mask; /* restrict bits */
int has_mac; /* length of MAC field */
int authlen; /* offset of MAC field */
int is_authentic = 0; /* cryptosum ok */
int retcode = AM_NOMATCH; /* match code */
keyid_t skeyid = 0; /* key IDs */
u_int32 opcode = 0; /* extension field opcode */
sockaddr_u *dstadr_sin; /* active runway */
struct peer *peer2; /* aux peer structure pointer */
endpt * match_ep; /* newpeer() local address */
l_fp p_org; /* origin timestamp */
l_fp p_rec; /* receive timestamp */
l_fp p_xmt; /* transmit timestamp */
#ifdef OPENSSL
struct autokey *ap; /* autokey structure pointer */
int rval; /* cookie snatcher */
keyid_t pkeyid = 0, tkeyid = 0; /* key IDs */
#endif /* OPENSSL */
#ifdef HAVE_NTP_SIGND
static unsigned char zero_key[16];
#endif /* HAVE_NTP_SIGND */
/*
* Monitor the packet and get restrictions. Note that the packet
* length for control and private mode packets must be checked
* by the service routines. Some restrictions have to be handled
* later in order to generate a kiss-o'-death packet.
*/
/*
* Bogus port check is before anything, since it probably
* reveals a clogging attack.
*/
sys_received++;
if (SRCPORT(&rbufp->recv_srcadr) < NTP_PORT) {
sys_badlength++;
return; /* bogus port */
}
restrict_mask = restrictions(&rbufp->recv_srcadr);
#ifdef DEBUG
if (debug > 1)
printf("receive: at %ld %s<-%s flags %x restrict %03x\n",
current_time, stoa(&rbufp->dstadr->sin),
stoa(&rbufp->recv_srcadr),
rbufp->dstadr->flags, restrict_mask);
#endif
pkt = &rbufp->recv_pkt;
hisversion = PKT_VERSION(pkt->li_vn_mode);
hisleap = PKT_LEAP(pkt->li_vn_mode);
hismode = (int)PKT_MODE(pkt->li_vn_mode);
hisstratum = PKT_TO_STRATUM(pkt->stratum);
if (restrict_mask & RES_IGNORE) {
sys_restricted++;
return; /* ignore everything */
}
if (hismode == MODE_PRIVATE) {
if (restrict_mask & RES_NOQUERY) {
sys_restricted++;
return; /* no query private */
}
process_private(rbufp, ((restrict_mask &
RES_NOMODIFY) == 0));
return;
}
if (hismode == MODE_CONTROL) {
if (restrict_mask & RES_NOQUERY) {
sys_restricted++;
return; /* no query control */
}
process_control(rbufp, restrict_mask);
return;
}
if (restrict_mask & RES_DONTSERVE) {
sys_restricted++;
return; /* no time serve */
}
/*
* This is for testing. If restricted drop ten percent of
* surviving packets.
*/
if (restrict_mask & RES_TIMEOUT) {
if ((double)ntp_random() / 0x7fffffff < .1) {
sys_restricted++;
return; /* no flakeway */
}
}
/*
* Version check must be after the query packets, since they
* intentionally use an early version.
*/
if (hisversion == NTP_VERSION) {
sys_newversion++; /* new version */
} else if (!(restrict_mask & RES_VERSION) && hisversion >=
NTP_OLDVERSION) {
sys_oldversion++; /* previous version */
} else {
sys_badlength++;
return; /* old version */
}
/*
* Figure out his mode and validate the packet. This has some
* legacy raunch that probably should be removed. In very early
* NTP versions mode 0 was equivalent to what later versions
* would interpret as client mode.
*/
if (hismode == MODE_UNSPEC) {
if (hisversion == NTP_OLDVERSION) {
hismode = MODE_CLIENT;
} else {
sys_badlength++;
return; /* invalid mode */
}
}
/*
* Parse the extension field if present. We figure out whether
* an extension field is present by measuring the MAC size. If
* the number of words following the packet header is 0, no MAC
* is present and the packet is not authenticated. If 1, the
* packet is a crypto-NAK; if 3, the packet is authenticated
* with DES; if 5, the packet is authenticated with MD5; if 6,
* the packet is authenticated with SHA. If 2 or * 4, the packet
* is a runt and discarded forthwith. If greater than 6, an
* extension field is present, so we subtract the length of the
* field and go around again.
*/
authlen = LEN_PKT_NOMAC;
has_mac = rbufp->recv_length - authlen;
while (has_mac != 0) {
u_int32 len;
if (has_mac % 4 != 0 || has_mac < MIN_MAC_LEN) {
sys_badlength++;
return; /* bad length */
}
if (has_mac <= MAX_MAC_LEN) {
skeyid = ntohl(((u_int32 *)pkt)[authlen / 4]);
break;
} else {
opcode = ntohl(((u_int32 *)pkt)[authlen / 4]);
len = opcode & 0xffff;
if (len % 4 != 0 || len < 4 || len + authlen >
rbufp->recv_length) {
sys_badlength++;
return; /* bad length */
}
authlen += len;
has_mac -= len;
}
}
/*
* If authentication required, a MAC must be present.
*/
if (restrict_mask & RES_DONTTRUST && has_mac == 0) {
sys_restricted++;
return; /* access denied */
}
/*
* Update the MRU list and finger the cloggers. It can be a
* little expensive, so turn it off for production use.
*/
restrict_mask = ntp_monitor(rbufp, restrict_mask);
if (restrict_mask & RES_LIMITED) {
sys_limitrejected++;
if (!(restrict_mask & RES_KOD) || MODE_BROADCAST ==
hismode || MODE_SERVER == hismode)
return; /* rate exceeded */
if (hismode == MODE_CLIENT)
fast_xmit(rbufp, MODE_SERVER, skeyid,
restrict_mask);
else
fast_xmit(rbufp, MODE_ACTIVE, skeyid,
restrict_mask);
return; /* rate exceeded */
}
restrict_mask &= ~RES_KOD;
/*
* We have tossed out as many buggy packets as possible early in
* the game to reduce the exposure to a clogging attack. now we
* have to burn some cycles to find the association and
* authenticate the packet if required. Note that we burn only
* MD5 cycles, again to reduce exposure. There may be no
* matching association and that's okay.
*
* More on the autokey mambo. Normally the local interface is
* found when the association was mobilized with respect to a
* designated remote address. We assume packets arriving from
* the remote address arrive via this interface and the local
* address used to construct the autokey is the unicast address
* of the interface. However, if the sender is a broadcaster,
* the interface broadcast address is used instead.
* Notwithstanding this technobabble, if the sender is a
* multicaster, the broadcast address is null, so we use the
* unicast address anyway. Don't ask.
*/
peer = findpeer(rbufp, hismode, &retcode);
dstadr_sin = &rbufp->dstadr->sin;
NTOHL_FP(&pkt->org, &p_org);
NTOHL_FP(&pkt->rec, &p_rec);
NTOHL_FP(&pkt->xmt, &p_xmt);
/*
* Authentication is conditioned by three switches:
*
* NOPEER (RES_NOPEER) do not mobilize an association unless
* authenticated
* NOTRUST (RES_DONTTRUST) do not allow access unless
* authenticated (implies NOPEER)
* enable (sys_authenticate) master NOPEER switch, by default
* on
*
* The NOPEER and NOTRUST can be specified on a per-client basis
* using the restrict command. The enable switch if on implies
* NOPEER for all clients. There are four outcomes:
*
* NONE The packet has no MAC.
* OK the packet has a MAC and authentication succeeds
* ERROR the packet has a MAC and authentication fails
* CRYPTO crypto-NAK. The MAC has four octets only.
*
* Note: The AUTH(x, y) macro is used to filter outcomes. If x
* is zero, acceptable outcomes of y are NONE and OK. If x is
* one, the only acceptable outcome of y is OK.
*/
if (has_mac == 0) {
restrict_mask &= ~RES_MSSNTP;
is_authentic = AUTH_NONE; /* not required */
#ifdef DEBUG
if (debug)
printf(
"receive: at %ld %s<-%s mode %d len %d\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode,
authlen);
#endif
} else if (has_mac == 4) {
restrict_mask &= ~RES_MSSNTP;
is_authentic = AUTH_CRYPTO; /* crypto-NAK */
#ifdef DEBUG
if (debug)
printf(
"receive: at %ld %s<-%s mode %d keyid %08x len %d auth %d\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode, skeyid,
authlen + has_mac, is_authentic);
#endif
#ifdef HAVE_NTP_SIGND
/*
* If the signature is 20 bytes long, the last 16 of
* which are zero, then this is a Microsoft client
* wanting AD-style authentication of the server's
* reply.
*
* This is described in Microsoft's WSPP docs, in MS-SNTP:
* http://msdn.microsoft.com/en-us/library/cc212930.aspx
*/
} else if (has_mac == MAX_MD5_LEN && (restrict_mask & RES_MSSNTP) &&
(retcode == AM_FXMIT || retcode == AM_NEWPASS) &&
(memcmp(zero_key, (char *)pkt + authlen + 4, MAX_MD5_LEN - 4) ==
0)) {
is_authentic = AUTH_NONE;
#endif /* HAVE_NTP_SIGND */
} else {
restrict_mask &= ~RES_MSSNTP;
#ifdef OPENSSL
/*
* For autokey modes, generate the session key
* and install in the key cache. Use the socket
* broadcast or unicast address as appropriate.
*/
if (crypto_flags && skeyid > NTP_MAXKEY) {
/*
* More on the autokey dance (AKD). A cookie is
* constructed from public and private values.
* For broadcast packets, the cookie is public
* (zero). For packets that match no
* association, the cookie is hashed from the
* addresses and private value. For server
* packets, the cookie was previously obtained
* from the server. For symmetric modes, the
* cookie was previously constructed using an
* agreement protocol; however, should PKI be
* unavailable, we construct a fake agreement as
* the EXOR of the peer and host cookies.
*
* hismode ephemeral persistent
* =======================================
* active 0 cookie#
* passive 0% cookie#
* client sys cookie 0%
* server 0% sys cookie
* broadcast 0 0
*
* # if unsync, 0
* % can't happen
*/
if (has_mac < MAX_MD5_LEN) {
sys_badauth++;
return;
}
if (hismode == MODE_BROADCAST) {
/*
* For broadcaster, use the interface
* broadcast address when available;
* otherwise, use the unicast address
* found when the association was
* mobilized. However, if this is from
* the wildcard interface, game over.
*/
if (crypto_flags && rbufp->dstadr ==
any_interface) {
sys_restricted++;
return; /* no wildcard */
}
pkeyid = 0;
if (!SOCK_UNSPEC(&rbufp->dstadr->bcast))
dstadr_sin =
&rbufp->dstadr->bcast;
} else if (peer == NULL) {
pkeyid = session_key(
&rbufp->recv_srcadr, dstadr_sin, 0,
sys_private, 0);
} else {
pkeyid = peer->pcookie;
}
/*
* The session key includes both the public
* values and cookie. In case of an extension
* field, the cookie used for authentication
* purposes is zero. Note the hash is saved for
* use later in the autokey mambo.
*/
if (authlen > LEN_PKT_NOMAC && pkeyid != 0) {
session_key(&rbufp->recv_srcadr,
dstadr_sin, skeyid, 0, 2);
tkeyid = session_key(
&rbufp->recv_srcadr, dstadr_sin,
skeyid, pkeyid, 0);
} else {
tkeyid = session_key(
&rbufp->recv_srcadr, dstadr_sin,
skeyid, pkeyid, 2);
}
}
#endif /* OPENSSL */
/*
* Compute the cryptosum. Note a clogging attack may
* succeed in bloating the key cache. If an autokey,
* purge it immediately, since we won't be needing it
* again. If the packet is authentic, it can mobilize an
* association. Note that there is no key zero.
*/
if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen,
has_mac))
is_authentic = AUTH_ERROR;
else
is_authentic = AUTH_OK;
#ifdef OPENSSL
if (crypto_flags && skeyid > NTP_MAXKEY)
authtrust(skeyid, 0);
#endif /* OPENSSL */
#ifdef DEBUG
if (debug)
printf(
"receive: at %ld %s<-%s mode %d keyid %08x len %d auth %d\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode, skeyid,
authlen + has_mac, is_authentic);
#endif
}
/*
* The association matching rules are implemented by a set of
* routines and an association table. A packet matching an
* association is processed by the peer process for that
* association. If there are no errors, an ephemeral association
* is mobilized: a broadcast packet mobilizes a broadcast client
* aassociation; a manycast server packet mobilizes a manycast
* client association; a symmetric active packet mobilizes a
* symmetric passive association.
*/
switch (retcode) {
/*
* This is a client mode packet not matching any association. If
* an ordinary client, simply toss a server mode packet back
* over the fence. If a manycast client, we have to work a
* little harder.
*/
case AM_FXMIT:
/*
* If authentication OK, send a server reply; otherwise,
* send a crypto-NAK.
*/
if (!(rbufp->dstadr->flags & INT_MCASTOPEN)) {
if (AUTH(restrict_mask & RES_DONTTRUST,
is_authentic)) {
fast_xmit(rbufp, MODE_SERVER, skeyid,
restrict_mask);
} else if (is_authentic == AUTH_ERROR) {
fast_xmit(rbufp, MODE_SERVER, 0,
restrict_mask);
sys_badauth++;
} else {
sys_restricted++;
}
return; /* hooray */
}
/*
* This must be manycast. Do not respond if not
* configured as a manycast server.
*/
if (!sys_manycastserver) {
sys_restricted++;
return; /* not enabled */
}
/*
* Do not respond if we are not synchronized or our
* stratum is greater than the manycaster or the
* manycaster has already synchronized to us.
*/
if (sys_leap == LEAP_NOTINSYNC || sys_stratum >=
hisstratum || (!sys_cohort && sys_stratum ==
hisstratum + 1) || rbufp->dstadr->addr_refid ==
pkt->refid) {
sys_declined++;
return; /* no help */
}
/*
* Respond only if authentication succeeds. Don't do a
* crypto-NAK, as that would not be useful.
*/
if (AUTH(restrict_mask & RES_DONTTRUST, is_authentic))
fast_xmit(rbufp, MODE_SERVER, skeyid,
restrict_mask);
return; /* hooray */
/*
* This is a server mode packet returned in response to a client
* mode packet sent to a multicast group address. The origin
* timestamp is a good nonce to reliably associate the reply
* with what was sent. If there is no match, that's curious and
* could be an intruder attempting to clog, so we just ignore
* it.
*
* If the packet is authentic and the manycast association is
* found, we mobilize a client association and copy pertinent
* variables from the manycast association to the new client
* association. If not, just ignore the packet.
*
* There is an implosion hazard at the manycast client, since
* the manycast servers send the server packet immediately. If
* the guy is already here, don't fire up a duplicate.
*/
case AM_MANYCAST:
if (!AUTH(sys_authenticate | (restrict_mask &
(RES_NOPEER | RES_DONTTRUST)), is_authentic)) {
sys_restricted++;
return; /* access denied */
}
/*
* Do not respond if unsynchronized or stratum is below
* the floor or at or above the ceiling.
*/
if (hisleap == LEAP_NOTINSYNC || hisstratum <
sys_floor || hisstratum >= sys_ceiling) {
sys_declined++;
return; /* no help */
}
if ((peer2 = findmanycastpeer(rbufp)) == NULL) {
sys_restricted++;
return; /* not enabled */
}
if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr,
MODE_CLIENT, hisversion, NTP_MINDPOLL, NTP_MAXDPOLL,
FLAG_PREEMPT, MDF_UCAST | MDF_ACLNT, 0, skeyid)) ==
NULL) {
sys_declined++;
return; /* ignore duplicate */
}
/*
* We don't need these, but it warms the billboards.
*/
if (peer2->flags & FLAG_IBURST)
peer->flags |= FLAG_IBURST;
peer->minpoll = peer2->minpoll;
peer->maxpoll = peer2->maxpoll;
break;
/*
* This is the first packet received from a broadcast server. If
* the packet is authentic and we are enabled as broadcast
* client, mobilize a broadcast client association. We don't
* kiss any frogs here.
*/
case AM_NEWBCL:
if (sys_bclient == 0) {
sys_restricted++;
return; /* not enabled */
}
if (!AUTH(sys_authenticate | (restrict_mask &
(RES_NOPEER | RES_DONTTRUST)), is_authentic)) {
sys_restricted++;
return; /* access denied */
}
/*
* Do not respond if unsynchronized or stratum is below
* the floor or at or above the ceiling.
*/
if (hisleap == LEAP_NOTINSYNC || hisstratum <
sys_floor || hisstratum >= sys_ceiling) {
sys_declined++;
return; /* no help */
}
#ifdef OPENSSL
/*
* Do not respond if Autokey and the opcode is not a
* CRYPTO_ASSOC response with associationn ID.
*/
if (crypto_flags && skeyid > NTP_MAXKEY && (opcode &
0xffff0000) != (CRYPTO_ASSOC | CRYPTO_RESP)) {
sys_declined++;
return; /* protocol error */
}
#endif /* OPENSSL */
/*
* Broadcasts received via a multicast address may
* arrive after a unicast volley has begun
* with the same remote address. newpeer() will not
* find duplicate associations on other local endpoints
* if a non-NULL endpoint is supplied. multicastclient
* ephemeral associations are unique across all local
* endpoints.
*/
if (!(INT_MCASTOPEN & rbufp->dstadr->flags))
match_ep = rbufp->dstadr;
else
match_ep = NULL;
/*
* Determine whether to execute the initial volley.
*/
if (sys_bdelay != 0) {
#ifdef OPENSSL
/*
* If a two-way exchange is not possible,
* neither is Autokey.
*/
if (crypto_flags && skeyid > NTP_MAXKEY) {
sys_restricted++;
return; /* no autokey */
}
#endif /* OPENSSL */
/*
* Do not execute the volley. Start out in
* broadcast client mode.
*/
peer = newpeer(&rbufp->recv_srcadr, match_ep,
MODE_BCLIENT, hisversion, pkt->ppoll,
pkt->ppoll, FLAG_PREEMPT, MDF_BCLNT, 0,
skeyid);
if (NULL == peer) {
sys_restricted++;
return; /* ignore duplicate */
} else {
peer->delay = sys_bdelay;
peer->bias = -sys_bdelay / 2.;
}
break;
}
/*
* Execute the initial volley in order to calibrate the
* propagation delay and run the Autokey protocol.
*
* Note that the minpoll is taken from the broadcast
* packet, normally 6 (64 s) and that the poll interval
* is fixed at this value.
*/
peer = newpeer(&rbufp->recv_srcadr, match_ep,
MODE_CLIENT, hisversion, pkt->ppoll, pkt->ppoll,
FLAG_BC_VOL | FLAG_IBURST | FLAG_PREEMPT, MDF_BCLNT,
0, skeyid);
if (NULL == peer) {
sys_restricted++;
return; /* ignore duplicate */
}
#ifdef OPENSSL
if (skeyid > NTP_MAXKEY)
crypto_recv(peer, rbufp);
#endif /* OPENSSL */
return; /* hooray */
/*
* This is the first packet received from a symmetric active
* peer. If the packet is authentic and the first he sent,
* mobilize a passive association. If not, kiss the frog.
*/
case AM_NEWPASS:
if (!AUTH(sys_authenticate | (restrict_mask &
(RES_NOPEER | RES_DONTTRUST)), is_authentic)) {
/*
* If authenticated but cannot mobilize an
* association, send a symmetric passive
* response without mobilizing an association.
* This is for drat broken Windows clients. See
* Microsoft KB 875424 for preferred workaround.
*/
if (AUTH(restrict_mask & RES_DONTTRUST,
is_authentic)) {
fast_xmit(rbufp, MODE_PASSIVE, skeyid,
restrict_mask);
return; /* hooray */
}
if (is_authentic == AUTH_ERROR) {
fast_xmit(rbufp, MODE_ACTIVE, 0,
restrict_mask);
sys_restricted++;
}
}
/*
* Do not respond if synchronized and stratum is either
* below the floor or at or above the ceiling. Note,
* this allows an unsynchronized peer to synchronize to
* us. It would be very strange if he did and then was
* nipped, but that could only happen if we were
* operating at the top end of the range.
*/
if (hisleap != LEAP_NOTINSYNC && (hisstratum <
sys_floor || hisstratum >= sys_ceiling)) {
sys_declined++;
return; /* no help */
}
/*
* The message is correctly authenticated and
* allowed. Mobiliae a symmetric passive association.
*/
if ((peer = newpeer(&rbufp->recv_srcadr,
rbufp->dstadr, MODE_PASSIVE, hisversion, pkt->ppoll,
NTP_MAXDPOLL, FLAG_PREEMPT, MDF_UCAST, 0,
skeyid)) == NULL) {
sys_declined++;
return; /* ignore duplicate */
}
break;
/*
* Process regular packet. Nothing special.
*/
case AM_PROCPKT:
break;
/*
* A passive packet matches a passive association. This is
* usually the result of reconfiguring a client on the fly. As
* this association might be legitamate and this packet an
* attempt to deny service, just ignore it.
*/
case AM_ERR:
sys_declined++;
return;
/*
* For everything else there is the bit bucket.
*/
default:
sys_declined++;
return;
}
#ifdef OPENSSL
/*
* If the association is configured for Autokey, the packet must
* have a public key ID; if not, the packet must have a
* symmetric key ID.
*/
if (is_authentic != AUTH_CRYPTO && (((peer->flags &
FLAG_SKEY) && skeyid <= NTP_MAXKEY) || (!(peer->flags &
FLAG_SKEY) && skeyid > NTP_MAXKEY))) {
sys_badauth++;
return;
}
#endif /* OPENSSL */
peer->received++;
peer->flash &= ~PKT_TEST_MASK;
if (peer->flags & FLAG_XBOGUS) {
peer->flags &= ~FLAG_XBOGUS;
peer->flash |= TEST3;
}
/*
* Next comes a rigorous schedule of timestamp checking. If the
* transmit timestamp is zero, the server has not initialized in
* interleaved modes or is horribly broken.
*/
if (L_ISZERO(&p_xmt)) {
peer->flash |= TEST3; /* unsynch */
/*
* If the transmit timestamp duplicates a previous one, the
* packet is a replay. This prevents the bad guys from replaying
* the most recent packet, authenticated or not.
*/
} else if (L_ISEQU(&peer->xmt, &p_xmt)) {
peer->flash |= TEST1; /* duplicate */
peer->oldpkt++;
return;
/*
* If this is a broadcast mode packet, skip further checking. If
* an intial volley, bail out now and let the client do its
* stuff. If the origin timestamp is nonzero, this is an
* interleaved broadcast. so restart the protocol.
*/
} else if (hismode == MODE_BROADCAST) {
if (!L_ISZERO(&p_org) && !(peer->flags & FLAG_XB)) {
peer->flags |= FLAG_XB;
peer->aorg = p_xmt;
peer->borg = rbufp->recv_time;
report_event(PEVNT_XLEAVE, peer, NULL);
return;
}
/*
* Check for bogus packet in basic mode. If found, switch to
* interleaved mode and resynchronize, but only after confirming
* the packet is not bogus in symmetric interleaved mode.
*/
} else if (peer->flip == 0) {
if (!L_ISEQU(&p_org, &peer->aorg)) {
peer->bogusorg++;
peer->flash |= TEST2; /* bogus */
if (!L_ISZERO(&peer->dst) && L_ISEQU(&p_org,
&peer->dst)) {
peer->flip = 1;
report_event(PEVNT_XLEAVE, peer, NULL);
}
} else {
L_CLR(&peer->aorg);
}
/*
* Check for valid nonzero timestamp fields.
*/
} else if (L_ISZERO(&p_org) || L_ISZERO(&p_rec) ||
L_ISZERO(&peer->dst)) {
peer->flash |= TEST3; /* unsynch */
/*
* Check for bogus packet in interleaved symmetric mode. This
* can happen if a packet is lost, duplicat or crossed. If
* found, flip and resynchronize.
*/
} else if (!L_ISZERO(&peer->dst) && !L_ISEQU(&p_org,
&peer->dst)) {
peer->bogusorg++;
peer->flags |= FLAG_XBOGUS;
peer->flash |= TEST2; /* bogus */
}
/*
* Update the state variables.
*/
if (peer->flip == 0) {
if (hismode != MODE_BROADCAST)
peer->rec = p_xmt;
peer->dst = rbufp->recv_time;
}
peer->xmt = p_xmt;
/*
* If this is a crypto_NAK, the server cannot authenticate a
* client packet. The server might have just changed keys. Clear
* the association and restart the protocol.
*/
if (is_authentic == AUTH_CRYPTO) {
report_event(PEVNT_AUTH, peer, "crypto_NAK");
peer->flash |= TEST5; /* bad auth */
peer->badauth++;
if (peer->flags & FLAG_PREEMPT) {
unpeer(peer);
return;
}
#ifdef OPENSSL
if (peer->crypto)
peer_clear(peer, "AUTH");
#endif /* OPENSSL */
return;
/*
* If the digest fails, the client cannot authenticate a server
* reply to a client packet previously sent. The loopback check
* is designed to avoid a bait-and-switch attack, which was
* possible in past versions. If symmetric modes, return a
* crypto-NAK. The peer should restart the protocol.
*/
} else if (!AUTH(has_mac || (restrict_mask & RES_DONTTRUST),
is_authentic)) {
report_event(PEVNT_AUTH, peer, "digest");
peer->flash |= TEST5; /* bad auth */
peer->badauth++;
if (hismode == MODE_ACTIVE || hismode == MODE_PASSIVE)
fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask);
if (peer->flags & FLAG_PREEMPT) {
unpeer(peer);
return;
}
#ifdef OPENSSL
if (peer->crypto)
peer_clear(peer, "AUTH");
#endif /* OPENSSL */
return;
}
/*
* Set the peer ppoll to the maximum of the packet ppoll and the
* peer minpoll. If a kiss-o'-death, set the peer minpoll to
* this maximumn and advance the headway to give the sender some
* headroom. Very intricate.
*/
peer->ppoll = max(peer->minpoll, pkt->ppoll);
if (hismode == MODE_SERVER && hisleap == LEAP_NOTINSYNC &&
hisstratum == STRATUM_UNSPEC && memcmp(&pkt->refid,
"RATE", 4) == 0) {
peer->selbroken++;
report_event(PEVNT_RATE, peer, NULL);
if (pkt->ppoll > peer->minpoll)
peer->minpoll = peer->ppoll;
peer->burst = peer->retry = 0;
peer->throttle = (NTP_SHIFT + 1) * (1 << peer->minpoll);
poll_update(peer, pkt->ppoll);
return; /* kiss-o'-death */
}
/*
* That was hard and I am sweaty, but the packet is squeaky
* clean. Get on with real work.
*/
peer->timereceived = current_time;
if (is_authentic == AUTH_OK)
peer->flags |= FLAG_AUTHENTIC;
else
peer->flags &= ~FLAG_AUTHENTIC;
#ifdef OPENSSL
/*
* More autokey dance. The rules of the cha-cha are as follows:
*
* 1. If there is no key or the key is not auto, do nothing.
*
* 2. If this packet is in response to the one just previously
* sent or from a broadcast server, do the extension fields.
* Otherwise, assume bogosity and bail out.
*
* 3. If an extension field contains a verified signature, it is
* self-authenticated and we sit the dance.
*
* 4. If this is a server reply, check only to see that the
* transmitted key ID matches the received key ID.
*
* 5. Check to see that one or more hashes of the current key ID
* matches the previous key ID or ultimate original key ID
* obtained from the broadcaster or symmetric peer. If no
* match, sit the dance and call for new autokey values.
*
* In case of crypto error, fire the orchestra, stop dancing and
* restart the protocol.
*/
if (peer->flags & FLAG_SKEY) {
/*
* Decrement remaining audokey hashes. This isn't
* perfect if a packet is lost, but results in no harm.
*/
ap = (struct autokey *)peer->recval.ptr;
if (ap != NULL) {
if (ap->seq > 0)
ap->seq--;
}
peer->flash |= TEST8;
rval = crypto_recv(peer, rbufp);
if (rval == XEVNT_OK) {
peer->unreach = 0;
} else {
if (rval == XEVNT_ERR) {
report_event(PEVNT_RESTART, peer,
"crypto error");
peer_clear(peer, "CRYP");
peer->flash |= TEST9; /* bad crypt */
if (peer->flags & FLAG_PREEMPT)
unpeer(peer);
}
return;
}
/*
* If server mode, verify the receive key ID matches
* the transmit key ID.
*/
if (hismode == MODE_SERVER) {
if (skeyid == peer->keyid)
peer->flash &= ~TEST8;
/*
* If an extension field is present, verify only that it
* has been correctly signed. We don't need a sequence
* check here, but the sequence continues.
*/
} else if (!(peer->flash & TEST8)) {
peer->pkeyid = skeyid;
/*
* Now the fun part. Here, skeyid is the current ID in
* the packet, pkeyid is the ID in the last packet and
* tkeyid is the hash of skeyid. If the autokey values
* have not been received, this is an automatic error.
* If so, check that the tkeyid matches pkeyid. If not,
* hash tkeyid and try again. If the number of hashes
* exceeds the number remaining in the sequence, declare
* a successful failure and refresh the autokey values.
*/
} else if (ap != NULL) {
int i;
for (i = 0; ; i++) {
if (tkeyid == peer->pkeyid ||
tkeyid == ap->key) {
peer->flash &= ~TEST8;
peer->pkeyid = skeyid;
ap->seq -= i;
break;
}
if (i > ap->seq) {
peer->crypto &=
~CRYPTO_FLAG_AUTO;
break;
}
tkeyid = session_key(
&rbufp->recv_srcadr, dstadr_sin,
tkeyid, pkeyid, 0);
}
if (peer->flash & TEST8)
report_event(PEVNT_AUTH, peer, "keylist");
}
if (!(peer->crypto & CRYPTO_FLAG_PROV)) /* test 9 */
peer->flash |= TEST8; /* bad autokey */
/*
* The maximum lifetime of the protocol is about one
* week before restarting the Autokey protocol to
* refreshed certificates and leapseconds values.
*/
if (current_time > peer->refresh) {
report_event(PEVNT_RESTART, peer,
"crypto refresh");
peer_clear(peer, "TIME");
return;
}
}
#endif /* OPENSSL */
/*
* The dance is complete and the flash bits have been lit. Toss
* the packet over the fence for processing, which may light up
* more flashers.
*/
process_packet(peer, pkt, rbufp->recv_length);
/*
* In interleaved mode update the state variables. Also adjust the
* transmit phase to avoid crossover.
*/
if (peer->flip != 0) {
peer->rec = p_rec;
peer->dst = rbufp->recv_time;
if (peer->nextdate - current_time < (1 << min(peer->ppoll,
peer->hpoll)) / 2)
peer->nextdate++;
else
peer->nextdate--;
}
}
/*
* process_packet - Packet Procedure, a la Section 3.4.4 of the
* specification. Or almost, at least. If we're in here we have a
* reasonable expectation that we will be having a long term
* relationship with this host.
*/
void
process_packet(
register struct peer *peer,
register struct pkt *pkt,
u_int len
)
{
double t34, t21;
double p_offset, p_del, p_disp;
l_fp p_rec, p_xmt, p_org, p_reftime, ci;
u_char pmode, pleap, pstratum;
char statstr[NTP_MAXSTRLEN];
#ifdef ASSYM
int itemp;
double etemp, ftemp, td;
#endif /* ASSYM */
sys_processed++;
peer->processed++;
p_del = FPTOD(NTOHS_FP(pkt->rootdelay));
p_offset = 0;
p_disp = FPTOD(NTOHS_FP(pkt->rootdisp));
NTOHL_FP(&pkt->reftime, &p_reftime);
NTOHL_FP(&pkt->org, &p_org);
NTOHL_FP(&pkt->rec, &p_rec);
NTOHL_FP(&pkt->xmt, &p_xmt);
pmode = PKT_MODE(pkt->li_vn_mode);
pleap = PKT_LEAP(pkt->li_vn_mode);
pstratum = PKT_TO_STRATUM(pkt->stratum);
/*
* Capture the header values in the client/peer association..
*/
record_raw_stats(&peer->srcadr, peer->dstadr ?
&peer->dstadr->sin : NULL, &p_org, &p_rec, &p_xmt,
&peer->dst);
peer->leap = pleap;
peer->stratum = min(pstratum, STRATUM_UNSPEC);
peer->pmode = pmode;
peer->precision = pkt->precision;
peer->rootdelay = p_del;
peer->rootdisp = p_disp;
peer->refid = pkt->refid; /* network byte order */
peer->reftime = p_reftime;
/*
* First, if either burst mode is armed, enable the burst.
* Compute the headway for the next packet and delay if
* necessary to avoid exceeding the threshold.
*/
if (peer->retry > 0) {
peer->retry = 0;
if (peer->reach)
peer->burst = min(1 << (peer->hpoll -
peer->minpoll), NTP_SHIFT) - 1;
else
peer->burst = NTP_IBURST - 1;
if (peer->burst > 0)
peer->nextdate = current_time;
}
poll_update(peer, peer->hpoll);
/*
* Verify the server is synchronized; that is, the leap bits,
* stratum and root distance are valid.
*/
if (pleap == LEAP_NOTINSYNC || /* test 6 */
pstratum < sys_floor || pstratum >= sys_ceiling)
peer->flash |= TEST6; /* bad synch or strat */
if (p_del / 2 + p_disp >= MAXDISPERSE) /* test 7 */
peer->flash |= TEST7; /* bad header */
/*
* If any tests fail at this point, the packet is discarded.
* Note that some flashers may have already been set in the
* receive() routine.
*/
if (peer->flash & PKT_TEST_MASK) {
peer->seldisptoolarge++;
#ifdef DEBUG
if (debug)
printf("packet: flash header %04x\n",
peer->flash);
#endif
return;
}
/*
* If the peer was previously unreachable, raise a trap. In any
* case, mark it reachable.
*/
if (!peer->reach) {
report_event(PEVNT_REACH, peer, NULL);
peer->timereachable = current_time;
}
peer->reach |= 1;
/*
* For a client/server association, calculate the clock offset,
* roundtrip delay and dispersion. The equations are reordered
* from the spec for more efficient use of temporaries. For a
* broadcast association, offset the last measurement by the
* computed delay during the client/server volley. Note the
* computation of dispersion includes the system precision plus
* that due to the frequency error since the origin time.
*
* It is very important to respect the hazards of overflow. The
* only permitted operation on raw timestamps is subtraction,
* where the result is a signed quantity spanning from 68 years
* in the past to 68 years in the future. To avoid loss of
* precision, these calculations are done using 64-bit integer
* arithmetic. However, the offset and delay calculations are
* sums and differences of these first-order differences, which
* if done using 64-bit integer arithmetic, would be valid over
* only half that span. Since the typical first-order
* differences are usually very small, they are converted to 64-
* bit doubles and all remaining calculations done in floating-
* double arithmetic. This preserves the accuracy while
* retaining the 68-year span.
*
* There are three interleaving schemes, basic, interleaved
* symmetric and interleaved broadcast. The timestamps are
* idioscyncratically different. See the onwire briefing/white
* paper at www.eecis.udel.edu/~mills for details.
*
* Interleaved symmetric mode
* t1 = peer->aorg/borg, t2 = peer->rec, t3 = p_xmt,
* t4 = peer->dst
*/
if (peer->flip != 0) {
ci = p_xmt; /* t3 - t4 */
L_SUB(&ci, &peer->dst);
LFPTOD(&ci, t34);
ci = p_rec; /* t2 - t1 */
if (peer->flip > 0)
L_SUB(&ci, &peer->borg);
else
L_SUB(&ci, &peer->aorg);
LFPTOD(&ci, t21);
p_del = t21 - t34;
p_offset = (t21 + t34) / 2.;
if (p_del < 0 || p_del > 1.) {
sprintf(statstr, "t21 %.6f t34 %.6f", t21, t34);
report_event(PEVNT_XERR, peer, statstr);
return;
}
/*
* Broadcast modes
*/
} else if (peer->pmode == MODE_BROADCAST) {
/*
* Interleaved broadcast mode. Use interleaved timestamps.
* t1 = peer->borg, t2 = p_org, t3 = p_org, t4 = aorg
*/
if (peer->flags & FLAG_XB) {
ci = p_org; /* delay */
L_SUB(&ci, &peer->aorg);
LFPTOD(&ci, t34);
ci = p_org; /* t2 - t1 */
L_SUB(&ci, &peer->borg);
LFPTOD(&ci, t21);
peer->aorg = p_xmt;
peer->borg = peer->dst;
if (t34 < 0 || t34 > 1.) {
sprintf(statstr,
"offset %.6f delay %.6f", t21, t34);
report_event(PEVNT_XERR, peer, statstr);
return;
}
p_offset = t21;
peer->xleave = t34;
/*
* Basic broadcast - use direct timestamps.
* t3 = p_xmt, t4 = peer->dst
*/
} else {
ci = p_xmt; /* t3 - t4 */
L_SUB(&ci, &peer->dst);
LFPTOD(&ci, t34);
p_offset = t34;
}
/*
* When calibration is complete and the clock is
* synchronized, the bias is calculated as the difference
* between the unicast timestamp and the broadcast
* timestamp. This works for both basic and interleaved
* modes.
*/
if (FLAG_BC_VOL & peer->flags) {
peer->flags &= ~FLAG_BC_VOL;
peer->delay = (peer->offset - p_offset) * 2;
}
p_del = peer->delay;
p_offset += p_del / 2;
/*
* Basic mode, otherwise known as the old fashioned way.
*
* t1 = p_org, t2 = p_rec, t3 = p_xmt, t4 = peer->dst
*/
} else {
ci = p_xmt; /* t3 - t4 */
L_SUB(&ci, &peer->dst);
LFPTOD(&ci, t34);
ci = p_rec; /* t2 - t1 */
L_SUB(&ci, &p_org);
LFPTOD(&ci, t21);
p_del = fabs(t21 - t34);
p_offset = (t21 + t34) / 2.;
}
p_offset += peer->bias;
p_disp = LOGTOD(sys_precision) + LOGTOD(peer->precision) +
clock_phi * p_del;
#if ASSYM
/*
* This code calculates the outbound and inbound data rates by
* measuring the differences between timestamps at different
* packet lengths. This is helpful in cases of large asymmetric
* delays commonly experienced on deep space communication
* links.
*/
if (peer->t21_last > 0 && peer->t34_bytes > 0) {
itemp = peer->t21_bytes - peer->t21_last;
if (itemp > 25) {
etemp = t21 - peer->t21;
if (fabs(etemp) > 1e-6) {
ftemp = itemp / etemp;
if (ftemp > 1000.)
peer->r21 = ftemp;
}
}
itemp = len - peer->t34_bytes;
if (itemp > 25) {
etemp = -t34 - peer->t34;
if (fabs(etemp) > 1e-6) {
ftemp = itemp / etemp;
if (ftemp > 1000.)
peer->r34 = ftemp;
}
}
}
/*
* The following section compensates for different data rates on
* the outbound (d21) and inbound (t34) directions. To do this,
* it finds t such that r21 * t - r34 * (d - t) = 0, where d is
* the roundtrip delay. Then it calculates the correction as a
* fraction of d.
*/
peer->t21 = t21;
peer->t21_last = peer->t21_bytes;
peer->t34 = -t34;
peer->t34_bytes = len;
#ifdef DEBUG
if (debug > 1)
printf("packet: t21 %.9lf %d t34 %.9lf %d\n", peer->t21,
peer->t21_bytes, peer->t34, peer->t34_bytes);
#endif
if (peer->r21 > 0 && peer->r34 > 0 && p_del > 0) {
if (peer->pmode != MODE_BROADCAST)
td = (peer->r34 / (peer->r21 + peer->r34) -
.5) * p_del;
else
td = 0;
/*
* Unfortunately, in many cases the errors are
* unacceptable, so for the present the rates are not
* used. In future, we might find conditions where the
* calculations are useful, so this should be considered
* a work in progress.
*/
t21 -= td;
t34 -= td;
#ifdef DEBUG
if (debug > 1)
printf("packet: del %.6lf r21 %.1lf r34 %.1lf %.6lf\n",
p_del, peer->r21 / 1e3, peer->r34 / 1e3,
td);
#endif
}
#endif /* ASSYM */
/*
* That was awesome. Now hand off to the clock filter.
*/
clock_filter(peer, p_offset, p_del, p_disp);
/*
* If we are in broadcast calibrate mode, return to broadcast
* client mode when the client is fit and the autokey dance is
* complete.
*/
if ((FLAG_BC_VOL & peer->flags) && MODE_CLIENT == peer->hmode &&
!(TEST11 & peer_unfit(peer))) { /* distance exceeded */
#ifdef OPENSSL
if (peer->flags & FLAG_SKEY) {
if (!(~peer->crypto & CRYPTO_FLAG_ALL))
peer->hmode = MODE_BCLIENT;
} else {
peer->hmode = MODE_BCLIENT;
}
#else /* OPENSSL */
peer->hmode = MODE_BCLIENT;
#endif /* OPENSSL */
}
}
/*
* clock_update - Called at system process update intervals.
*/
static void
clock_update(
struct peer *peer /* peer structure pointer */
)
{
double dtemp;
l_fp now;
#ifdef HAVE_LIBSCF_H
char *fmri;
#endif /* HAVE_LIBSCF_H */
/*
* Update the system state variables. We do this very carefully,
* as the poll interval might need to be clamped differently.
*/
sys_peer = peer;
sys_epoch = peer->epoch;
if (sys_poll < peer->minpoll)
sys_poll = peer->minpoll;
if (sys_poll > peer->maxpoll)
sys_poll = peer->maxpoll;
poll_update(peer, sys_poll);
sys_stratum = min(peer->stratum + 1, STRATUM_UNSPEC);
if (peer->stratum == STRATUM_REFCLOCK ||
peer->stratum == STRATUM_UNSPEC)
sys_refid = peer->refid;
else
sys_refid = addr2refid(&peer->srcadr);
dtemp = sys_jitter + fabs(sys_offset) + peer->disp +
(peer->delay + peer->rootdelay) / 2 + clock_phi *
(current_time - peer->update);
sys_rootdisp = dtemp + peer->rootdisp;
sys_rootdelay = peer->delay + peer->rootdelay;
sys_reftime = peer->dst;
#ifdef DEBUG
if (debug)
printf(
"clock_update: at %lu sample %lu associd %d\n",
current_time, peer->epoch, peer->associd);
#endif
/*
* Comes now the moment of truth. Crank the clock discipline and
* see what comes out.
*/
switch (local_clock(peer, sys_offset)) {
/*
* Clock exceeds panic threshold. Life as we know it ends.
*/
case -1:
#ifdef HAVE_LIBSCF_H
/*
* For Solaris enter the maintenance mode.
*/
if ((fmri = getenv("SMF_FMRI")) != NULL) {
if (smf_maintain_instance(fmri, 0) < 0) {
printf("smf_maintain_instance: %s\n",
scf_strerror(scf_error()));
exit(1);
}
/*
* Sleep until SMF kills us.
*/
for (;;)
pause();
}
#endif /* HAVE_LIBSCF_H */
exit (-1);
/* not reached */
/*
* Clock was stepped. Flush all time values of all peers.
*/
case 2:
clear_all();
sys_leap = LEAP_NOTINSYNC;
sys_stratum = STRATUM_UNSPEC;
memcpy(&sys_refid, "STEP", 4);
sys_rootdelay = 0;
sys_rootdisp = 0;
L_CLR(&sys_reftime);
sys_jitter = LOGTOD(sys_precision);
leapsec = 0;
break;
/*
* Clock was slewed. Handle the leapsecond stuff.
*/
case 1:
/*
* If this is the first time the clock is set, reset the
* leap bits. If crypto, the timer will goose the setup
* process.
*/
if (sys_leap == LEAP_NOTINSYNC) {
sys_leap = LEAP_NOWARNING;
#ifdef OPENSSL
if (crypto_flags)
crypto_update();
#endif /* OPENSSL */
}
/*
* If the leapseconds values are from file or network
* and the leap is in the future, schedule a leap at the
* given epoch. Otherwise, if the number of survivor
* leap bits is greater than half the number of
* survivors, schedule a leap for the end of the current
* month.
*/
get_systime(&now);
if (leap_sec > 0) {
if (leap_sec > now.l_ui) {
sys_tai = leap_tai - 1;
if (leapsec == 0)
report_event(EVNT_ARMED, NULL,
NULL);
leapsec = leap_sec - now.l_ui;
} else {
sys_tai = leap_tai;
}
break;
} else if (leap_vote > sys_survivors / 2) {
leap_peers = now.l_ui + leap_month(now.l_ui);
if (leap_peers > now.l_ui) {
if (leapsec == 0)
report_event(PEVNT_ARMED, peer,
NULL);
leapsec = leap_peers - now.l_ui;
}
} else if (leapsec > 0) {
report_event(EVNT_DISARMED, NULL, NULL);
leapsec = 0;
}
break;
/*
* Popcorn spike or step threshold exceeded. Pretend it never
* happened.
*/
default:
break;
}
}
/*
* poll_update - update peer poll interval
*/
void
poll_update(
struct peer *peer, /* peer structure pointer */
int mpoll
)
{
int hpoll, minpkt;
u_long next, utemp;
/*
* This routine figures out when the next poll should be sent.
* That turns out to be wickedly complicated. One problem is
* that sometimes the time for the next poll is in the past when
* the poll interval is reduced. We watch out for races here
* between the receive process and the poll process.
*
* First, bracket the poll interval according to the type of
* association and options. If a fixed interval is configured,
* use minpoll. This primarily is for reference clocks, but
* works for any association. Otherwise, clamp the poll interval
* between minpoll and maxpoll.
*/
if (peer->cast_flags & MDF_BCLNT)
hpoll = peer->minpoll;
else
hpoll = max(min(peer->maxpoll, mpoll), peer->minpoll);
#ifdef OPENSSL
/*
* If during the crypto protocol the poll interval has changed,
* the lifetimes in the key list are probably bogus. Purge the
* the key list and regenerate it later.
*/
if ((peer->flags & FLAG_SKEY) && hpoll != peer->hpoll)
key_expire(peer);
#endif /* OPENSSL */
peer->hpoll = hpoll;
/*
* There are three variables important for poll scheduling, the
* current time (current_time), next scheduled time (nextdate)
* and the earliest time (utemp). The earliest time is 2 s
* seconds, but could be more due to rate management. When
* sending in a burst, use the earliest time. When not in a
* burst but with a reply pending, send at the earliest time
* unless the next scheduled time has not advanced. This can
* only happen if multiple replies are peinding in the same
* response interval. Otherwise, send at the later of the next
* scheduled time and the earliest time.
*
* Now we figure out if there is an override. If a burst is in
* progress and we get called from the receive process, just
* slink away. If called from the poll process, delay 1 s for a
* reference clock, otherwise 2 s.
*/
minpkt = 1 << ntp_minpkt;
utemp = current_time + max(peer->throttle - (NTP_SHIFT - 1) *
(1 << peer->minpoll), minpkt);
if (peer->burst > 0) {
if (peer->nextdate > current_time)
return;
#ifdef REFCLOCK
else if (peer->flags & FLAG_REFCLOCK)
peer->nextdate = current_time + RESP_DELAY;
#endif /* REFCLOCK */
else
peer->nextdate = utemp;
#ifdef OPENSSL
/*
* If a burst is not in progress and a crypto response message
* is pending, delay 2 s, but only if this is a new interval.
*/
} else if (peer->cmmd != NULL) {
if (peer->nextdate > current_time) {
if (peer->nextdate + minpkt != utemp)
peer->nextdate = utemp;
} else {
peer->nextdate = utemp;
}
#endif /* OPENSSL */
/*
* The ordinary case. If a retry, use minpoll; if unreachable,
* use host poll; otherwise, use the minimum of host and peer
* polls; In other words, oversampling is okay but
* understampling is evil. Use the maximum of this value and the
* headway. If the average headway is greater than the headway
* threshold, increase the headway by the minimum interval.
*/
} else {
if (peer->retry > 0)
hpoll = peer->minpoll;
else if (!(peer->reach))
hpoll = peer->hpoll;
else
hpoll = min(peer->ppoll, peer->hpoll);
#ifdef REFCLOCK
if (peer->flags & FLAG_REFCLOCK)
next = 1 << hpoll;
else
next = ((0x1000UL | (ntp_random() & 0x0ff)) <<
hpoll) >> 12;
#else /* REFCLOCK */
next = ((0x1000UL | (ntp_random() & 0x0ff)) << hpoll) >>
12;
#endif /* REFCLOCK */
next += peer->outdate;
if (next > utemp)
peer->nextdate = next;
else
peer->nextdate = utemp;
hpoll = peer->throttle - (1 << peer->minpoll);
if (hpoll > 0)
peer->nextdate += minpkt;
}
#ifdef DEBUG
if (debug > 1)
printf("poll_update: at %lu %s poll %d burst %d retry %d head %d early %lu next %lu\n",
current_time, ntoa(&peer->srcadr), peer->hpoll,
peer->burst, peer->retry, peer->throttle,
utemp - current_time, peer->nextdate -
current_time);
#endif
}
/*
* peer_clear - clear peer filter registers. See Section 3.4.8 of the
* spec.
*/
void
peer_clear(
struct peer *peer, /* peer structure */
char *ident /* tally lights */
)
{
int i;
#ifdef OPENSSL
/*
* If cryptographic credentials have been acquired, toss them to
* Valhalla. Note that autokeys are ephemeral, in that they are
* tossed immediately upon use. Therefore, the keylist can be
* purged anytime without needing to preserve random keys. Note
* that, if the peer is purged, the cryptographic variables are
* purged, too. This makes it much harder to sneak in some
* unauthenticated data in the clock filter.
*/
key_expire(peer);
if (peer->iffval != NULL)
BN_free(peer->iffval);
value_free(&peer->cookval);
value_free(&peer->recval);
value_free(&peer->encrypt);
value_free(&peer->sndval);
if (peer->cmmd != NULL)
free(peer->cmmd);
if (peer->subject != NULL)
free(peer->subject);
if (peer->issuer != NULL)
free(peer->issuer);
#endif /* OPENSSL */
/*
* Clear all values, including the optional crypto values above.
*/
memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO);
peer->ppoll = peer->maxpoll;
peer->hpoll = peer->minpoll;
peer->disp = MAXDISPERSE;
peer->flash = peer_unfit(peer);
peer->jitter = LOGTOD(sys_precision);
/*
* If interleave mode, initialize the alternate origin switch.
*/
if (peer->flags & FLAG_XLEAVE)
peer->flip = 1;
for (i = 0; i < NTP_SHIFT; i++) {
peer->filter_order[i] = i;
peer->filter_disp[i] = MAXDISPERSE;
}
#ifdef REFCLOCK
if (!(peer->flags & FLAG_REFCLOCK)) {
peer->leap = LEAP_NOTINSYNC;
peer->stratum = STRATUM_UNSPEC;
memcpy(&peer->refid, ident, 4);
}
#else
peer->leap = LEAP_NOTINSYNC;
peer->stratum = STRATUM_UNSPEC;
memcpy(&peer->refid, ident, 4);
#endif /* REFCLOCK */
/*
* During initialization use the association count to spread out
* the polls at one-second intervals. Otherwise, randomize over
* the minimum poll interval in order to avoid broadcast
* implosion.
*/
peer->nextdate = peer->update = peer->outdate = current_time;
if (initializing) {
peer->nextdate += peer_associations;
} else if (peer->hmode == MODE_PASSIVE) {
peer->nextdate += 1 << ntp_minpkt;
} else {
peer->nextdate += ntp_random() % peer_associations;
}
#ifdef OPENSSL
peer->refresh = current_time + (1 << NTP_REFRESH);
#endif /* OPENSSL */
#ifdef DEBUG
if (debug)
printf(
"peer_clear: at %ld next %ld associd %d refid %s\n",
current_time, peer->nextdate, peer->associd,
ident);
#endif
}
/*
* clock_filter - add incoming clock sample to filter register and run
* the filter procedure to find the best sample.
*/
void
clock_filter(
struct peer *peer, /* peer structure pointer */
double sample_offset, /* clock offset */
double sample_delay, /* roundtrip delay */
double sample_disp /* dispersion */
)
{
double dst[NTP_SHIFT]; /* distance vector */
int ord[NTP_SHIFT]; /* index vector */
int i, j, k, m;
double dtemp, etemp;
char tbuf[80];
/*
* A sample consists of the offset, delay, dispersion and epoch
* of arrival. The offset and delay are determined by the on-
* wire protocol. The dispersion grows from the last outbound
* packet to the arrival of this one increased by the sum of the
* peer precision and the system precision as required by the
* error budget. First, shift the new arrival into the shift
* register discarding the oldest one.
*/
j = peer->filter_nextpt;
peer->filter_offset[j] = sample_offset;
peer->filter_delay[j] = sample_delay;
peer->filter_disp[j] = sample_disp;
peer->filter_epoch[j] = current_time;
j = (j + 1) % NTP_SHIFT;
peer->filter_nextpt = j;
/*
* Update dispersions since the last update and at the same
* time initialize the distance and index lists. Since samples
* become increasingly uncorrelated beyond the Allan intercept,
* only under exceptional cases will an older sample be used.
* Therefore, the distance list uses a compound metric. If the
* dispersion is greater than the maximum dispersion, clamp the
* distance at that value. If the time since the last update is
* less than the Allan intercept use the delay; otherwise, use
* the sum of the delay and dispersion.
*/
dtemp = clock_phi * (current_time - peer->update);
peer->update = current_time;
for (i = NTP_SHIFT - 1; i >= 0; i--) {
if (i != 0)
peer->filter_disp[j] += dtemp;
if (peer->filter_disp[j] >= MAXDISPERSE) {
peer->filter_disp[j] = MAXDISPERSE;
dst[i] = MAXDISPERSE;
} else if (peer->update - peer->filter_epoch[j] >
ULOGTOD(allan_xpt)) {
dst[i] = peer->filter_delay[j] +
peer->filter_disp[j];
} else {
dst[i] = peer->filter_delay[j];
}
ord[i] = j;
j = (j + 1) % NTP_SHIFT;
}
/*
* If the clock discipline has stabilized, sort the samples by
* distance.
*/
if (sys_leap != LEAP_NOTINSYNC) {
for (i = 1; i < NTP_SHIFT; i++) {
for (j = 0; j < i; j++) {
if (dst[j] > dst[i]) {
k = ord[j];
ord[j] = ord[i];
ord[i] = k;
etemp = dst[j];
dst[j] = dst[i];
dst[i] = etemp;
}
}
}
}
/*
* Copy the index list to the association structure so ntpq
* can see it later. Prune the distance list to leave only
* samples less than the maximum dispersion, which disfavors
* uncorrelated samples older than the Allan intercept. To
* further improve the jitter estimate, of the remainder leave
* only samples less than the maximum distance, but keep at
* least two samples for jitter calculation.
*/
m = 0;
for (i = 0; i < NTP_SHIFT; i++) {
peer->filter_order[i] = (u_char) ord[i];
if (dst[i] >= MAXDISPERSE || (m >= 2 && dst[i] >=
sys_maxdist))
continue;
m++;
}
/*
* Compute the dispersion and jitter. The dispersion is weighted
* exponentially by NTP_FWEIGHT (0.5) so it is normalized close
* to 1.0. The jitter is the RMS differences relative to the
* lowest delay sample.
*/
peer->disp = peer->jitter = 0;
k = ord[0];
for (i = NTP_SHIFT - 1; i >= 0; i--) {
j = ord[i];
peer->disp = NTP_FWEIGHT * (peer->disp +
peer->filter_disp[j]);
if (i < m)
peer->jitter += DIFF(peer->filter_offset[j],
peer->filter_offset[k]);
}
/*
* If no acceptable samples remain in the shift register,
* quietly tiptoe home leaving only the dispersion. Otherwise,
* save the offset, delay and jitter. Note the jitter must not
* be less than the precision.
*/
if (m == 0) {
clock_select();
return;
}
etemp = fabs(peer->offset - peer->filter_offset[k]);
peer->offset = peer->filter_offset[k];
peer->delay = peer->filter_delay[k];
if (m > 1)
peer->jitter /= m - 1;
peer->jitter = max(SQRT(peer->jitter), LOGTOD(sys_precision));
/*
* If the the new sample and the current sample are both valid
* and the difference between their offsets exceeds CLOCK_SGATE
* (3) times the jitter and the interval between them is less
* than twice the host poll interval, consider the new sample
* a popcorn spike and ignore it.
*/
if (peer->disp < sys_maxdist && peer->filter_disp[k] <
sys_maxdist && etemp > CLOCK_SGATE * peer->jitter &&
peer->filter_epoch[k] - peer->epoch < 2. *
ULOGTOD(peer->hpoll)) {
snprintf(tbuf, sizeof(tbuf), "%.6f s", etemp);
report_event(PEVNT_POPCORN, peer, tbuf);
return;
}
/*
* A new minimum sample is useful only if it is later than the
* last one used. In this design the maximum lifetime of any
* sample is not greater than eight times the poll interval, so
* the maximum interval between minimum samples is eight
* packets.
*/
if (peer->filter_epoch[k] <= peer->epoch) {
#if DEBUG
if (debug)
printf("clock_filter: old sample %lu\n", current_time -
peer->filter_epoch[k]);
#endif
return;
}
peer->epoch = peer->filter_epoch[k];
/*
* The mitigated sample statistics are saved for later
* processing. If not synchronized or not in a burst, tickle the
* clock select algorithm.
*/
record_peer_stats(&peer->srcadr, ctlpeerstatus(peer),
peer->offset, peer->delay, peer->disp, peer->jitter);
#ifdef DEBUG
if (debug)
printf(
"clock_filter: n %d off %.6f del %.6f dsp %.6f jit %.6f\n",
m, peer->offset, peer->delay, peer->disp,
peer->jitter);
#endif
if (peer->burst == 0 || sys_leap == LEAP_NOTINSYNC)
clock_select();
}
/*
* clock_select - find the pick-of-the-litter clock
*
* LOCKCLOCK: (1) If the local clock is the prefer peer, it will always
* be enabled, even if declared falseticker, (2) only the prefer peer
* caN Be selected as the system peer, (3) if the external source is
* down, the system leap bits are set to 11 and the stratum set to
* infinity.
*/
void
clock_select(void)
{
struct peer *peer;
int i, j, k, n;
int nlist, nl3;
int allow, osurv;
double d, e, f, g;
double high, low;
double seljitter;
double synch[NTP_MAXASSOC], error[NTP_MAXASSOC];
double orphmet = 2.0 * U_INT32_MAX; /* 2x is greater than */
struct peer *osys_peer = NULL;
struct peer *sys_prefer = NULL; /* prefer peer */
struct peer *typesystem = NULL;
struct peer *typeorphan = NULL;
#ifdef REFCLOCK
struct peer *typeacts = NULL;
struct peer *typelocal = NULL;
struct peer *typepps = NULL;
#endif /* REFCLOCK */
static int list_alloc = 0;
static struct endpoint *endpoint = NULL;
static int *indx = NULL;
static struct peer **peer_list = NULL;
static u_int endpoint_size = 0;
static u_int indx_size = 0;
static u_int peer_list_size = 0;
/*
* Initialize and create endpoint, index and peer lists big
* enough to handle all associations.
*/
osys_peer = sys_peer;
osurv = sys_survivors;
sys_survivors = 0;
#ifdef LOCKCLOCK
sys_leap = LEAP_NOTINSYNC;
sys_stratum = STRATUM_UNSPEC;
memcpy(&sys_refid, "DOWN", 4);
#endif /* LOCKCLOCK */
nlist = 0;
for (n = 0; n < NTP_HASH_SIZE; n++)
nlist += peer_hash_count[n];
if (nlist > list_alloc) {
if (list_alloc > 0) {
free(endpoint);
free(indx);
free(peer_list);
}
while (list_alloc < nlist) {
list_alloc += 5;
endpoint_size += 5 * 3 * sizeof(*endpoint);
indx_size += 5 * 3 * sizeof(*indx);
peer_list_size += 5 * sizeof(*peer_list);
}
endpoint = (struct endpoint *)emalloc(endpoint_size);
indx = (int *)emalloc(indx_size);
peer_list = (struct peer **)emalloc(peer_list_size);
}
/*
* Initially, we populate the island with all the rifraff peers
* that happen to be lying around. Those with seriously
* defective clocks are immediately booted off the island. Then,
* the falsetickers are culled and put to sea. The truechimers
* remaining are subject to repeated rounds where the most
* unpopular at each round is kicked off. When the population
* has dwindled to sys_minclock, the survivors split a million
* bucks and collectively crank the chimes.
*/
nlist = nl3 = 0; /* none yet */
for (n = 0; n < NTP_HASH_SIZE; n++) {
for (peer = peer_hash[n]; peer != NULL; peer =
peer->next) {
peer->new_status = CTL_PST_SEL_REJECT;
/*
* Leave the island immediately if the peer is
* unfit to synchronize.
*/
if (peer_unfit(peer))
continue;
/*
* If this peer is an orphan parent, elect the
* one with the lowest metric defined as the
* IPv4 address or the first 64 bits of the
* hashed IPv6 address. To ensure convergence
* on the same selected orphan, consider as
* well that this system may have the lowest
* metric and be the orphan parent. If this
* system wins, sys_peer will be NULL to trigger
* orphan mode in timer().
*/
if (peer->stratum == sys_orphan) {
u_int32 localmet;
u_int32 peermet;
if (peer->dstadr != NULL)
localmet = ntohl(peer->dstadr->addr_refid);
else
localmet = U_INT32_MAX;
peermet = ntohl(addr2refid(&peer->srcadr));
if (peermet < localmet &&
peermet < orphmet) {
typeorphan = peer;
orphmet = peermet;
}
continue;
}
/*
* If this peer could have the orphan parent
* as a synchronization ancestor, exclude it
* from selection to avoid forming a
* synchronization loop within the orphan mesh,
* triggering stratum climb to infinity
* instability. Peers at stratum higher than
* the orphan stratum could have the orphan
* parent in ancestry so are excluded.
* See http://bugs.ntp.org/2050
*/
if (peer->stratum > sys_orphan)
continue;
#ifdef REFCLOCK
/*
* The following are special cases. We deal
* with them later.
*/
if (!(peer->flags & FLAG_PREFER)) {
switch (peer->refclktype) {
case REFCLK_LOCALCLOCK:
if (typelocal == NULL)
typelocal = peer;
continue;
case REFCLK_ACTS:
if (typeacts == NULL)
typeacts = peer;
continue;
}
}
#endif /* REFCLOCK */
/*
* If we get this far, the peer can stay on the
* island, but does not yet have the immunity
* idol.
*/
peer->new_status = CTL_PST_SEL_SANE;
peer_list[nlist++] = peer;
/*
* Insert each interval endpoint on the sorted
* list.
*/
e = peer->offset; /* Upper end */
f = root_distance(peer);
e = e + f;
for (i = nl3 - 1; i >= 0; i--) {
if (e >= endpoint[indx[i]].val)
break;
indx[i + 3] = indx[i];
}
indx[i + 3] = nl3;
endpoint[nl3].type = 1;
endpoint[nl3++].val = e;
e = e - f; /* Center point */
for (; i >= 0; i--) {
if (e >= endpoint[indx[i]].val)
break;
indx[i + 2] = indx[i];
}
indx[i + 2] = nl3;
endpoint[nl3].type = 0;
endpoint[nl3++].val = e;
e = e - f; /* Lower end */
for (; i >= 0; i--) {
if (e >= endpoint[indx[i]].val)
break;
indx[i + 1] = indx[i];
}
indx[i + 1] = nl3;
endpoint[nl3].type = -1;
endpoint[nl3++].val = e;
}
}
#ifdef DEBUG
if (debug > 2)
for (i = 0; i < nl3; i++)
printf("select: endpoint %2d %.6f\n",
endpoint[indx[i]].type,
endpoint[indx[i]].val);
#endif
/*
* This is the actual algorithm that cleaves the truechimers
* from the falsetickers. The original algorithm was described
* in Keith Marzullo's dissertation, but has been modified for
* better accuracy.
*
* Briefly put, we first assume there are no falsetickers, then
* scan the candidate list first from the low end upwards and
* then from the high end downwards. The scans stop when the
* number of intersections equals the number of candidates less
* the number of falsetickers. If this doesn't happen for a
* given number of falsetickers, we bump the number of
* falsetickers and try again. If the number of falsetickers
* becomes equal to or greater than half the number of
* candidates, the Albanians have won the Byzantine wars and
* correct synchronization is not possible.
*
* Here, nlist is the number of candidates and allow is the
* number of falsetickers. Upon exit, the truechimers are the
* survivors with offsets not less than low and not greater than
* high. There may be none of them.
*/
low = 1e9;
high = -1e9;
for (allow = 0; 2 * allow < nlist; allow++) {
int found;
/*
* Bound the interval (low, high) as the largest
* interval containing points from presumed truechimers.
*/
found = 0;
n = 0;
for (i = 0; i < nl3; i++) {
low = endpoint[indx[i]].val;
n -= endpoint[indx[i]].type;
if (n >= nlist - allow)
break;
if (endpoint[indx[i]].type == 0)
found++;
}
n = 0;
for (j = nl3 - 1; j >= 0; j--) {
high = endpoint[indx[j]].val;
n += endpoint[indx[j]].type;
if (n >= nlist - allow)
break;
if (endpoint[indx[j]].type == 0)
found++;
}
/*
* If the number of candidates found outside the
* interval is greater than the number of falsetickers,
* then at least one truechimer is outside the interval,
* so go around again. This is what makes this algorithm
* different than Marzullo's.
*/
if (found > allow)
continue;
/*
* If an interval containing truechimers is found, stop.
* If not, increase the number of falsetickers and go
* around again.
*/
if (high > low)
break;
}
/*
* Clustering algorithm. Construct candidate list in order first
* by stratum then by root distance, but keep only the best
* NTP_MAXASSOC of them. Scan the list to find falsetickers, who
* leave the island immediately. The TRUE peer is always a
* truechimer. We must leave at least one peer to collect the
* million bucks.
*/
j = 0;
for (i = 0; i < nlist; i++) {
peer = peer_list[i];
if (nlist > 1 && (peer->offset <= low || peer->offset >=
high) && !(peer->flags & FLAG_TRUE))
continue;
#ifdef REFCLOCK
/*
* Eligible PPS peers must survive the intersection
* algorithm. Use the first one found, but don't
* include any of them in the cluster population.
*/
if (peer->flags & FLAG_PPS) {
if (typepps == NULL)
typepps = peer;
continue;
}
#endif /* REFCLOCK */
/*
* The metric is the scaled root distance at the next
* poll interval plus the peer stratum.
*/
d = (root_distance(peer) + clock_phi * (peer->nextdate -
current_time)) / sys_maxdist + peer->stratum;
if (j >= NTP_MAXASSOC) {
if (d >= synch[j - 1])
continue;
else
j--;
}
for (k = j; k > 0; k--) {
if (d >= synch[k - 1])
break;
peer_list[k] = peer_list[k - 1];
error[k] = error[k - 1];
synch[k] = synch[k - 1];
}
peer_list[k] = peer;
error[k] = peer->jitter;
synch[k] = d;
j++;
}
nlist = j;
/*
* If no survivors remain at this point, check if the modem
* driver, local driver or orphan parent in that order. If so,
* nominate the first one found as the only survivor.
* Otherwise, give up and leave the island to the rats.
*/
if (nlist == 0) {
error[0] = 0;
synch[0] = 0;
#ifdef REFCLOCK
if (typeacts != NULL) {
peer_list[0] = typeacts;
nlist = 1;
} else if (typelocal != NULL) {
peer_list[0] = typelocal;
nlist = 1;
} else
#endif /* REFCLOCK */
if (typeorphan != NULL) {
peer_list[0] = typeorphan;
nlist = 1;
}
}
/*
* Mark the candidates at this point as truechimers.
*/
for (i = 0; i < nlist; i++) {
peer_list[i]->new_status = CTL_PST_SEL_SELCAND;
#ifdef DEBUG
if (debug > 1)
printf("select: survivor %s %f\n",
stoa(&peer_list[i]->srcadr), synch[i]);
#endif
}
/*
* Now, vote outlyers off the island by select jitter weighted
* by root distance. Continue voting as long as there are more
* than sys_minclock survivors and the minimum select jitter is
* greater than the maximum peer jitter. Stop if we are about to
* discard a TRUE or PREFER peer, who of course has the
* immunity idol.
*/
seljitter = 0;
while (1) {
d = 1e9;
e = -1e9;
f = g = 0;
k = 0;
for (i = 0; i < nlist; i++) {
if (error[i] < d)
d = error[i];
f = 0;
if (nlist > 1) {
for (j = 0; j < nlist; j++)
f += DIFF(peer_list[j]->offset,
peer_list[i]->offset);
f = SQRT(f / (nlist - 1));
}
if (f * synch[i] > e) {
g = f;
e = f * synch[i];
k = i;
}
}
f = max(f, LOGTOD(sys_precision));
if (nlist <= sys_minsane || nlist <= sys_minclock) {
break;
} else if (f <= d || peer_list[k]->flags &
(FLAG_TRUE | FLAG_PREFER)) {
seljitter = f;
break;
}
#ifdef DEBUG
if (debug > 2)
printf(
"select: drop %s seljit %.6f jit %.6f\n",
ntoa(&peer_list[k]->srcadr), g, d);
#endif
if (nlist > sys_maxclock)
peer_list[k]->new_status = CTL_PST_SEL_EXCESS;
for (j = k + 1; j < nlist; j++) {
peer_list[j - 1] = peer_list[j];
synch[j - 1] = synch[j];
error[j - 1] = error[j];
}
nlist--;
}
/*
* What remains is a list usually not greater than sys_minclock
* peers. Note that the head of the list is the system peer at
* the lowest stratum and that unsynchronized peers cannot
* survive this far.
*
* While at it, count the number of leap warning bits found.
* This will be used later to vote the system leap warning bit.
* If a leap warning bit is found on a reference clock, the vote
* is always won.
*/
leap_vote = 0;
for (i = 0; i < nlist; i++) {
peer = peer_list[i];
peer->unreach = 0;
peer->new_status = CTL_PST_SEL_SYNCCAND;
sys_survivors++;
if (peer->leap == LEAP_ADDSECOND) {
if (peer->flags & FLAG_REFCLOCK)
leap_vote = nlist;
else
leap_vote++;
}
if (peer->flags & FLAG_PREFER)
sys_prefer = peer;
}
/*
* Unless there are at least sys_misane survivors, leave the
* building dark. Otherwise, do a clockhop dance. Ordinarily,
* use the first survivor on the survivor list. However, if the
* last selection is not first on the list, use it as long as
* it doesn't get too old or too ugly.
*/
if (nlist > 0 && nlist >= sys_minsane) {
double x;
typesystem = peer_list[0];
if (osys_peer == NULL || osys_peer == typesystem) {
sys_clockhop = 0;
} else if ((x = fabs(typesystem->offset -
osys_peer->offset)) < sys_mindisp) {
if (sys_clockhop == 0)
sys_clockhop = sys_mindisp;
else
sys_clockhop *= .5;
#ifdef DEBUG
if (debug)
printf("select: clockhop %d %.6f %.6f\n",
j, x, sys_clockhop);
#endif
if (fabs(x) < sys_clockhop)
typesystem = osys_peer;
else
sys_clockhop = 0;
} else {
sys_clockhop = 0;
}
}
/*
* Mitigation rules of the game. We have the pick of the
* litter in typesystem if any survivors are left. If
* there is a prefer peer, use its offset and jitter.
* Otherwise, use the combined offset and jitter of all kitters.
*/
if (typesystem != NULL) {
if (sys_prefer == NULL) {
typesystem->new_status = CTL_PST_SEL_SYSPEER;
clock_combine(peer_list, sys_survivors);
sys_jitter = SQRT(SQUARE(sys_jitter) +
SQUARE(seljitter));
} else {
typesystem = sys_prefer;
sys_clockhop = 0;
typesystem->new_status = CTL_PST_SEL_SYSPEER;
sys_offset = typesystem->offset;
sys_jitter = typesystem->jitter;
}
#ifdef DEBUG
if (debug)
printf("select: combine offset %.9f jitter %.9f\n",
sys_offset, sys_jitter);
#endif
}
#ifdef REFCLOCK
/*
* If a PPS driver is lit and the combined offset is less than
* 0.4 s, select the driver as the PPS peer and use its offset
* and jitter. However, if this is the atom driver, use it only
* if there is a prefer peer or there are no survivors and none
* are required.
*/
if (typepps != NULL && fabs(sys_offset) < 0.4 &&
(typepps->refclktype != REFCLK_ATOM_PPS ||
(typepps->refclktype == REFCLK_ATOM_PPS && (sys_prefer !=
NULL || (typesystem == NULL && sys_minsane == 0))))) {
typesystem = typepps;
sys_clockhop = 0;
typesystem->new_status = CTL_PST_SEL_PPS;
sys_offset = typesystem->offset;
sys_jitter = typesystem->jitter;
#ifdef DEBUG
if (debug)
printf("select: pps offset %.9f jitter %.9f\n",
sys_offset, sys_jitter);
#endif
}
#endif /* REFCLOCK */
/*
* If there are no survivors at this point, there is no
* system peer. If so and this is an old update, keep the
* current statistics, but do not update the clock.
*/
if (typesystem == NULL) {
if (osys_peer != NULL)
report_event(EVNT_NOPEER, NULL, NULL);
sys_peer = NULL;
for (n = 0; n < NTP_HASH_SIZE; n++)
for (peer = peer_hash[n]; peer != NULL; peer =
peer->next)
peer->status = peer->new_status;
return;
}
/*
* Do not use old data, as this may mess up the clock discipline
* stability.
*/
if (typesystem->epoch <= sys_epoch)
return;
/*
* We have found the alpha male. Wind the clock.
*/
if (osys_peer != typesystem)
report_event(PEVNT_NEWPEER, typesystem, NULL);
for (n = 0; n < NTP_HASH_SIZE; n++)
for (peer = peer_hash[n]; peer != NULL; peer =
peer->next)
peer->status = peer->new_status;
clock_update(typesystem);
}
/*
* clock_combine - compute system offset and jitter from selected peers
*/
static void
clock_combine(
struct peer **peers, /* survivor list */
int npeers /* number of survivors */
)
{
int i;
double x, y, z, w;
y = z = w = 0;
for (i = 0; i < npeers; i++) {
x = root_distance(peers[i]);
y += 1. / x;
z += peers[i]->offset / x;
w += SQUARE(peers[i]->offset - peers[0]->offset) / x;
}
sys_offset = z / y;
sys_jitter = SQRT(w / y);
}
/*
* root_distance - compute synchronization distance from peer to root
*/
static double
root_distance(
struct peer *peer /* peer structure pointer */
)
{
double dtemp;
/*
* Careful squeak here. The value returned must be greater than
* the minimum root dispersion in order to avoid clockhop with
* highly precise reference clocks. Note that the root distance
* cannot exceed the sys_maxdist, as this is the cutoff by the
* selection algorithm.
*/
dtemp = (peer->delay + peer->rootdelay) / 2 + peer->disp +
peer->rootdisp + clock_phi * (current_time - peer->update) +
peer->jitter;
if (dtemp < sys_mindisp)
dtemp = sys_mindisp;
return (dtemp);
}
/*
* peer_xmit - send packet for persistent association.
*/
static void
peer_xmit(
struct peer *peer /* peer structure pointer */
)
{
struct pkt xpkt; /* transmit packet */
int sendlen, authlen;
keyid_t xkeyid = 0; /* transmit key ID */
l_fp xmt_tx, xmt_ty;
if (!peer->dstadr) /* drop peers without interface */
return;
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.refid = sys_refid;
xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp));
HTONL_FP(&sys_reftime, &xpkt.reftime);
HTONL_FP(&peer->rec, &xpkt.org);
HTONL_FP(&peer->dst, &xpkt.rec);
/*
* If the received packet contains a MAC, the transmitted packet
* is authenticated and contains a MAC. If not, the transmitted
* packet is not authenticated.
*
* It is most important when autokey is in use that the local
* interface IP address be known before the first packet is
* sent. Otherwise, it is not possible to compute a correct MAC
* the recipient will accept. Thus, the I/O semantics have to do
* a little more work. In particular, the wildcard interface
* might not be usable.
*/
sendlen = LEN_PKT_NOMAC;
#ifdef OPENSSL
if (!(peer->flags & FLAG_SKEY) && peer->keyid == 0) {
#else
if (peer->keyid == 0) {
#endif /* OPENSSL */
/*
* Transmit a-priori timestamps
*/
get_systime(&xmt_tx);
if (peer->flip == 0) { /* basic mode */
peer->aorg = xmt_tx;
HTONL_FP(&xmt_tx, &xpkt.xmt);
} else { /* interleaved modes */
if (peer->hmode == MODE_BROADCAST) { /* bcst */
HTONL_FP(&xmt_tx, &xpkt.xmt);
if (peer->flip > 0)
HTONL_FP(&peer->borg,
&xpkt.org);
else
HTONL_FP(&peer->aorg,
&xpkt.org);
} else { /* symmetric */
if (peer->flip > 0)
HTONL_FP(&peer->borg,
&xpkt.xmt);
else
HTONL_FP(&peer->aorg,
&xpkt.xmt);
}
}
peer->t21_bytes = sendlen;
sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl],
&xpkt, sendlen);
peer->sent++;
peer->throttle += (1 << peer->minpoll) - 2;
/*
* Capture a-posteriori timestamps
*/
get_systime(&xmt_ty);
if (peer->flip != 0) { /* interleaved modes */
if (peer->flip > 0)
peer->aorg = xmt_ty;
else
peer->borg = xmt_ty;
peer->flip = -peer->flip;
}
L_SUB(&xmt_ty, &xmt_tx);
LFPTOD(&xmt_ty, peer->xleave);
#ifdef DEBUG
if (debug)
printf("transmit: at %ld %s->%s mode %d len %d\n",
current_time, peer->dstadr ?
stoa(&peer->dstadr->sin) : "-",
stoa(&peer->srcadr), peer->hmode, sendlen);
#endif
return;
}
/*
* Authentication is enabled, so the transmitted packet must be
* authenticated. If autokey is enabled, fuss with the various
* modes; otherwise, symmetric key cryptography is used.
*/
#ifdef OPENSSL
if (peer->flags & FLAG_SKEY) {
struct exten *exten; /* extension field */
/*
* The Public Key Dance (PKD): Cryptographic credentials
* are contained in extension fields, each including a
* 4-octet length/code word followed by a 4-octet
* association ID and optional additional data. Optional
* data includes a 4-octet data length field followed by
* the data itself. Request messages are sent from a
* configured association; response messages can be sent
* from a configured association or can take the fast
* path without ever matching an association. Response
* messages have the same code as the request, but have
* a response bit and possibly an error bit set. In this
* implementation, a message may contain no more than
* one command and one or more responses.
*
* Cryptographic session keys include both a public and
* a private componet. Request and response messages
* using extension fields are always sent with the
* private component set to zero. Packets without
* extension fields indlude the private component when
* the session key is generated.
*/
while (1) {
/*
* Allocate and initialize a keylist if not
* already done. Then, use the list in inverse
* order, discarding keys once used. Keep the
* latest key around until the next one, so
* clients can use client/server packets to
* compute propagation delay.
*
* Note that once a key is used from the list,
* it is retained in the key cache until the
* next key is used. This is to allow a client
* to retrieve the encrypted session key
* identifier to verify authenticity.
*
* If for some reason a key is no longer in the
* key cache, a birthday has happened or the key
* has expired, so the pseudo-random sequence is
* broken. In that case, purge the keylist and
* regenerate it.
*/
if (peer->keynumber == 0)
make_keylist(peer, peer->dstadr);
else
peer->keynumber--;
xkeyid = peer->keylist[peer->keynumber];
if (authistrusted(xkeyid))
break;
else
key_expire(peer);
}
peer->keyid = xkeyid;
exten = NULL;
switch (peer->hmode) {
/*
* In broadcast server mode the autokey values are
* required by the broadcast clients. Push them when a
* new keylist is generated; otherwise, push the
* association message so the client can request them at
* other times.
*/
case MODE_BROADCAST:
if (peer->flags & FLAG_ASSOC)
exten = crypto_args(peer, CRYPTO_AUTO |
CRYPTO_RESP, peer->associd, NULL);
else
exten = crypto_args(peer, CRYPTO_ASSOC |
CRYPTO_RESP, peer->associd, NULL);
break;
/*
* In symmetric modes the parameter, certificate,
* identity, cookie and autokey exchanges are
* required. The leapsecond exchange is optional. But, a
* peer will not believe the other peer until the other
* peer has synchronized, so the certificate exchange
* might loop until then. If a peer finds a broken
* autokey sequence, it uses the autokey exchange to
* retrieve the autokey values. In any case, if a new
* keylist is generated, the autokey values are pushed.
*/
case MODE_ACTIVE:
case MODE_PASSIVE:
/*
* Parameter, certificate and identity.
*/
if (!peer->crypto)
exten = crypto_args(peer, CRYPTO_ASSOC,
peer->associd, sys_hostname);
else if (!(peer->crypto & CRYPTO_FLAG_CERT))
exten = crypto_args(peer, CRYPTO_CERT,
peer->associd, peer->issuer);
else if (!(peer->crypto & CRYPTO_FLAG_VRFY))
exten = crypto_args(peer,
crypto_ident(peer), peer->associd,
NULL);
/*
* Cookie and autokey. We request the cookie
* only when the this peer and the other peer
* are synchronized. But, this peer needs the
* autokey values when the cookie is zero. Any
* time we regenerate the key list, we offer the
* autokey values without being asked. If for
* some reason either peer finds a broken
* autokey sequence, the autokey exchange is
* used to retrieve the autokey values.
*/
else if (sys_leap != LEAP_NOTINSYNC &&
peer->leap != LEAP_NOTINSYNC &&
!(peer->crypto & CRYPTO_FLAG_COOK))
exten = crypto_args(peer, CRYPTO_COOK,
peer->associd, NULL);
else if (!(peer->crypto & CRYPTO_FLAG_AUTO))
exten = crypto_args(peer, CRYPTO_AUTO,
peer->associd, NULL);
else if (peer->flags & FLAG_ASSOC &&
peer->crypto & CRYPTO_FLAG_SIGN)
exten = crypto_args(peer, CRYPTO_AUTO |
CRYPTO_RESP, peer->assoc, NULL);
/*
* Wait for clock sync, then sign the
* certificate and retrieve the leapsecond
* values.
*/
else if (sys_leap == LEAP_NOTINSYNC)
break;
else if (!(peer->crypto & CRYPTO_FLAG_SIGN))
exten = crypto_args(peer, CRYPTO_SIGN,
peer->associd, sys_hostname);
else if (!(peer->crypto & CRYPTO_FLAG_LEAP))
exten = crypto_args(peer, CRYPTO_LEAP,
peer->associd, NULL);
break;
/*
* In client mode the parameter, certificate, identity,
* cookie and sign exchanges are required. The
* leapsecond exchange is optional. If broadcast client
* mode the same exchanges are required, except that the
* autokey exchange is substitutes for the cookie
* exchange, since the cookie is always zero. If the
* broadcast client finds a broken autokey sequence, it
* uses the autokey exchange to retrieve the autokey
* values.
*/
case MODE_CLIENT:
/*
* Parameter, certificate and identity.
*/
if (!peer->crypto)
exten = crypto_args(peer, CRYPTO_ASSOC,
peer->associd, sys_hostname);
else if (!(peer->crypto & CRYPTO_FLAG_CERT))
exten = crypto_args(peer, CRYPTO_CERT,
peer->associd, peer->issuer);
else if (!(peer->crypto & CRYPTO_FLAG_VRFY))
exten = crypto_args(peer,
crypto_ident(peer), peer->associd,
NULL);
/*
* Cookie and autokey. These are requests, but
* we use the peer association ID with autokey
* rather than our own.
*/
else if (!(peer->crypto & CRYPTO_FLAG_COOK))
exten = crypto_args(peer, CRYPTO_COOK,
peer->associd, NULL);
else if (!(peer->crypto & CRYPTO_FLAG_AUTO))
exten = crypto_args(peer, CRYPTO_AUTO,
peer->assoc, NULL);
/*
* Wait for clock sync, then sign the
* certificate and retrieve the leapsecond
* values.
*/
else if (sys_leap == LEAP_NOTINSYNC)
break;
else if (!(peer->crypto & CRYPTO_FLAG_SIGN))
exten = crypto_args(peer, CRYPTO_SIGN,
peer->associd, sys_hostname);
else if (!(peer->crypto & CRYPTO_FLAG_LEAP))
exten = crypto_args(peer, CRYPTO_LEAP,
peer->associd, NULL);
break;
}
/*
* Add a queued extension field if present. This is
* always a request message, so the reply ID is already
* in the message. If an error occurs, the error bit is
* lit in the response.
*/
if (peer->cmmd != NULL) {
u_int32 temp32;
temp32 = CRYPTO_RESP;
peer->cmmd->opcode |= htonl(temp32);
sendlen += crypto_xmit(peer, &xpkt, NULL,
sendlen, peer->cmmd, 0);
free(peer->cmmd);
peer->cmmd = NULL;
}
/*
* Add an extension field created above. All but the
* autokey response message are request messages.
*/
if (exten != NULL) {
if (exten->opcode != 0)
sendlen += crypto_xmit(peer, &xpkt,
NULL, sendlen, exten, 0);
free(exten);
}
/*
* Calculate the next session key. Since extension
* fields are present, the cookie value is zero.
*/
if (sendlen > LEN_PKT_NOMAC) {
session_key(&peer->dstadr->sin, &peer->srcadr,
xkeyid, 0, 2);
}
}
#endif /* OPENSSL */
/*
* Transmit a-priori timestamps
*/
get_systime(&xmt_tx);
if (peer->flip == 0) { /* basic mode */
peer->aorg = xmt_tx;
HTONL_FP(&xmt_tx, &xpkt.xmt);
} else { /* interleaved modes */
if (peer->hmode == MODE_BROADCAST) { /* bcst */
HTONL_FP(&xmt_tx, &xpkt.xmt);
if (peer->flip > 0)
HTONL_FP(&peer->borg, &xpkt.org);
else
HTONL_FP(&peer->aorg, &xpkt.org);
} else { /* symmetric */
if (peer->flip > 0)
HTONL_FP(&peer->borg, &xpkt.xmt);
else
HTONL_FP(&peer->aorg, &xpkt.xmt);
}
}
xkeyid = peer->keyid;
authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
if (authlen == 0) {
report_event(PEVNT_AUTH, peer, "no key");
peer->flash |= TEST5; /* auth error */
peer->badauth++;
return;
}
sendlen += authlen;
#ifdef OPENSSL
if (xkeyid > NTP_MAXKEY)
authtrust(xkeyid, 0);
#endif /* OPENSSL */
if (sendlen > sizeof(xpkt)) {
msyslog(LOG_ERR, "proto: buffer overflow %u", sendlen);
exit (-1);
}
peer->t21_bytes = sendlen;
sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl], &xpkt,
sendlen);
peer->sent++;
peer->throttle += (1 << peer->minpoll) - 2;
/*
* Capture a-posteriori timestamps
*/
get_systime(&xmt_ty);
if (peer->flip != 0) { /* interleaved modes */
if (peer->flip > 0)
peer->aorg = xmt_ty;
else
peer->borg = xmt_ty;
peer->flip = -peer->flip;
}
L_SUB(&xmt_ty, &xmt_tx);
LFPTOD(&xmt_ty, peer->xleave);
#ifdef OPENSSL
#ifdef DEBUG
if (debug)
printf("transmit: at %ld %s->%s mode %d keyid %08x len %d index %d\n",
current_time, peer->dstadr ?
ntoa(&peer->dstadr->sin) : "-",
ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen,
peer->keynumber);
#endif
#else /* OPENSSL */
#ifdef DEBUG
if (debug)
printf("transmit: at %ld %s->%s mode %d keyid %08x len %d\n",
current_time, peer->dstadr ?
ntoa(&peer->dstadr->sin) : "-",
ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen);
#endif
#endif /* OPENSSL */
}
/*
* fast_xmit - Send packet for nonpersistent association. Note that
* neither the source or destination can be a broadcast address.
*/
static void
fast_xmit(
struct recvbuf *rbufp, /* receive packet pointer */
int xmode, /* receive mode */
keyid_t xkeyid, /* transmit key ID */
int flags /* restrict mask */
)
{
struct pkt xpkt; /* transmit packet structure */
struct pkt *rpkt; /* receive packet structure */
l_fp xmt_tx, xmt_ty;
int sendlen;
#ifdef OPENSSL
u_int32 temp32;
#endif
/*
* Initialize transmit packet header fields from the receive
* buffer provided. We leave the fields intact as received, but
* set the peer poll at the maximum of the receive peer poll and
* the system minimum poll (ntp_minpoll). This is for KoD rate
* control and not strictly specification compliant, but doesn't
* break anything.
*
* If the gazinta was from a multicast address, the gazoutta
* must go out another way.
*/
rpkt = &rbufp->recv_pkt;
if (rbufp->dstadr->flags & INT_MCASTOPEN)
rbufp->dstadr = findinterface(&rbufp->recv_srcadr);
/*
* If this is a kiss-o'-death (KoD) packet, show leap
* unsynchronized, stratum zero, reference ID the four-character
* kiss code and system root delay. Note we don't reveal the
* local time, so these packets can't be used for
* synchronization.
*/
if (flags & RES_KOD) {
sys_kodsent++;
xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC,
PKT_VERSION(rpkt->li_vn_mode), xmode);
xpkt.stratum = STRATUM_PKT_UNSPEC;
xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll);
memcpy(&xpkt.refid, "RATE", 4);
xpkt.org = rpkt->xmt;
xpkt.rec = rpkt->xmt;
xpkt.xmt = rpkt->xmt;
/*
* This is a normal packet. Use the system variables.
*/
} else {
xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap,
PKT_VERSION(rpkt->li_vn_mode), xmode);
xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll);
xpkt.precision = sys_precision;
xpkt.refid = sys_refid;
xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp));
HTONL_FP(&sys_reftime, &xpkt.reftime);
xpkt.org = rpkt->xmt;
HTONL_FP(&rbufp->recv_time, &xpkt.rec);
get_systime(&xmt_tx);
HTONL_FP(&xmt_tx, &xpkt.xmt);
}
#ifdef HAVE_NTP_SIGND
if (flags & RES_MSSNTP) {
send_via_ntp_signd(rbufp, xmode, xkeyid, flags, &xpkt);
return;
}
#endif /* HAVE_NTP_SIGND */
/*
* If the received packet contains a MAC, the transmitted packet
* is authenticated and contains a MAC. If not, the transmitted
* packet is not authenticated.
*/
sendlen = LEN_PKT_NOMAC;
if (rbufp->recv_length == sendlen) {
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt,
sendlen);
#ifdef DEBUG
if (debug)
printf(
"transmit: at %ld %s->%s mode %d len %d\n",
current_time, stoa(&rbufp->dstadr->sin),
stoa(&rbufp->recv_srcadr), xmode, sendlen);
#endif
return;
}
/*
* The received packet contains a MAC, so the transmitted packet
* must be authenticated. For symmetric key cryptography, use
* the predefined and trusted symmetric keys to generate the
* cryptosum. For autokey cryptography, use the server private
* value to generate the cookie, which is unique for every
* source-destination-key ID combination.
*/
#ifdef OPENSSL
if (xkeyid > NTP_MAXKEY) {
keyid_t cookie;
/*
* The only way to get here is a reply to a legitimate
* client request message, so the mode must be
* MODE_SERVER. If an extension field is present, there
* can be only one and that must be a command. Do what
* needs, but with private value of zero so the poor
* jerk can decode it. If no extension field is present,
* use the cookie to generate the session key.
*/
cookie = session_key(&rbufp->recv_srcadr,
&rbufp->dstadr->sin, 0, sys_private, 0);
if (rbufp->recv_length > sendlen + MAX_MAC_LEN) {
session_key(&rbufp->dstadr->sin,
&rbufp->recv_srcadr, xkeyid, 0, 2);
temp32 = CRYPTO_RESP;
rpkt->exten[0] |= htonl(temp32);
sendlen += crypto_xmit(NULL, &xpkt, rbufp,
sendlen, (struct exten *)rpkt->exten,
cookie);
} else {
session_key(&rbufp->dstadr->sin,
&rbufp->recv_srcadr, xkeyid, cookie, 2);
}
}
#endif /* OPENSSL */
get_systime(&xmt_tx);
sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
#ifdef OPENSSL
if (xkeyid > NTP_MAXKEY)
authtrust(xkeyid, 0);
#endif /* OPENSSL */
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen);
get_systime(&xmt_ty);
L_SUB(&xmt_ty, &xmt_tx);
sys_authdelay = xmt_ty;
#ifdef DEBUG
if (debug)
printf(
"transmit: at %ld %s->%s mode %d keyid %08x len %d\n",
current_time, ntoa(&rbufp->dstadr->sin),
ntoa(&rbufp->recv_srcadr), xmode, xkeyid, sendlen);
#endif
}
#ifdef OPENSSL
/*
* key_expire - purge the key list
*/
void
key_expire(
struct peer *peer /* peer structure pointer */
)
{
int i;
if (peer->keylist != NULL) {
for (i = 0; i <= peer->keynumber; i++)
authtrust(peer->keylist[i], 0);
free(peer->keylist);
peer->keylist = NULL;
}
value_free(&peer->sndval);
peer->keynumber = 0;
peer->flags &= ~FLAG_ASSOC;
#ifdef DEBUG
if (debug)
printf("key_expire: at %lu associd %d\n", current_time,
peer->associd);
#endif
}
#endif /* OPENSSL */
/*
* local_refid(peer) - check peer refid to avoid selecting peers
* currently synced to this ntpd.
*/
static int
local_refid(
struct peer * p
)
{
endpt * unicast_ep;
if (p->dstadr != NULL && !(INT_MCASTIF & p->dstadr->flags))
unicast_ep = p->dstadr;
else
unicast_ep = findinterface(&p->srcadr);
if (unicast_ep != NULL && p->refid == unicast_ep->addr_refid)
return TRUE;
else
return FALSE;
}
/*
* Determine if the peer is unfit for synchronization
*
* A peer is unfit for synchronization if
* > TEST10 bad leap or stratum below floor or at or above ceiling
* > TEST11 root distance exceeded for remote peer
* > TEST12 a direct or indirect synchronization loop would form
* > TEST13 unreachable or noselect
*/
int /* FALSE if fit, TRUE if unfit */
peer_unfit(
struct peer *peer /* peer structure pointer */
)
{
int rval = 0;
/*
* A stratum error occurs if (1) the server has never been
* synchronized, (2) the server stratum is below the floor or
* greater than or equal to the ceiling.
*/
if (peer->leap == LEAP_NOTINSYNC || peer->stratum < sys_floor ||
peer->stratum >= sys_ceiling)
rval |= TEST10; /* bad synch or stratum */
/*
* A distance error for a remote peer occurs if the root
* distance is greater than or equal to the distance threshold
* plus the increment due to one host poll interval.
*/
if (!(peer->flags & FLAG_REFCLOCK) && root_distance(peer) >=
sys_maxdist + clock_phi * ULOGTOD(peer->hpoll))
rval |= TEST11; /* distance exceeded */
/*
* A loop error occurs if the remote peer is synchronized to the
* local peer or if the remote peer is synchronized to the same
* server as the local peer but only if the remote peer is
* neither a reference clock nor an orphan.
*/
if (peer->stratum > 1 && local_refid(peer))
rval |= TEST12; /* synchronization loop */
/*
* An unreachable error occurs if the server is unreachable or
* the noselect bit is set.
*/
if (!peer->reach || (peer->flags & FLAG_NOSELECT))
rval |= TEST13; /* unreachable */
peer->flash &= ~PEER_TEST_MASK;
peer->flash |= rval;
return (rval);
}
/*
* Find the precision of this particular machine
*/
#define MINSTEP 100e-9 /* minimum clock increment (s) */
#define MAXSTEP 20e-3 /* maximum clock increment (s) */
#define MINLOOPS 5 /* minimum number of step samples */
/*
* This routine measures the system precision defined as the minimum of
* a sequence of differences between successive readings of the system
* clock. However, if a difference is less than MINSTEP, the clock has
* been read more than once during a clock tick and the difference is
* ignored. We set MINSTEP greater than zero in case something happens
* like a cache miss.
*/
int
default_get_precision(void)
{
l_fp val; /* current seconds fraction */
l_fp last; /* last seconds fraction */
l_fp diff; /* difference */
double tick; /* computed tick value */
double dtemp; /* scratch */
int i; /* log2 precision */
/*
* Loop to find precision value in seconds.
*/
tick = MAXSTEP;
i = 0;
get_systime(&last);
while (1) {
get_systime(&val);
diff = val;
L_SUB(&diff, &last);
last = val;
LFPTOD(&diff, dtemp);
if (dtemp < MINSTEP)
continue;
if (dtemp < tick)
tick = dtemp;
if (++i >= MINLOOPS)
break;
}
sys_tick = tick;
/*
* Find the nearest power of two.
*/
msyslog(LOG_NOTICE, "proto: precision = %.3f usec", tick * 1e6);
for (i = 0; tick <= 1; i++)
tick *= 2;
if (tick - 1 > 1 - tick / 2)
i--;
return (-i);
}
/*
* init_proto - initialize the protocol module's data
*/
void
init_proto(void)
{
l_fp dummy;
int i;
/*
* Fill in the sys_* stuff. Default is don't listen to
* broadcasting, require authentication.
*/
sys_leap = LEAP_NOTINSYNC;
sys_stratum = STRATUM_UNSPEC;
memcpy(&sys_refid, "INIT", 4);
sys_peer = NULL;
sys_rootdelay = 0;
sys_rootdisp = 0;
L_CLR(&sys_reftime);
sys_jitter = 0;
sys_precision = (s_char)default_get_precision();
get_systime(&dummy);
sys_survivors = 0;
sys_manycastserver = 0;
sys_bclient = 0;
sys_bdelay = 0;
sys_authenticate = 1;
sys_stattime = current_time;
proto_clr_stats();
for (i = 0; i < MAX_TTL; i++) {
sys_ttl[i] = (u_char)((i * 256) / MAX_TTL);
sys_ttlmax = i;
}
pps_enable = 0;
stats_control = 1;
}
/*
* proto_config - configure the protocol module
*/
void
proto_config(
int item,
u_long value,
double dvalue,
sockaddr_u *svalue
)
{
/*
* Figure out what he wants to change, then do it
*/
DPRINTF(2, ("proto_config: code %d value %lu dvalue %lf\n",
item, value, dvalue));
switch (item) {
/*
* enable and disable commands - arguments are Boolean.
*/
case PROTO_AUTHENTICATE: /* authentication (auth) */
sys_authenticate = value;
break;
case PROTO_BROADCLIENT: /* broadcast client (bclient) */
sys_bclient = (int)value;
if (sys_bclient == 0)
io_unsetbclient();
else
io_setbclient();
break;
#ifdef REFCLOCK
case PROTO_CAL: /* refclock calibrate (calibrate) */
cal_enable = value;
break;
#endif /* REFCLOCK */
case PROTO_KERNEL: /* kernel discipline (kernel) */
kern_enable = value;
break;
case PROTO_MONITOR: /* monitoring (monitor) */
if (value)
mon_start(MON_ON);
else
mon_stop(MON_ON);
break;
case PROTO_NTP: /* NTP discipline (ntp) */
ntp_enable = value;
break;
case PROTO_PPS: /* PPS discipline (pps) */
pps_enable = value;
break;
case PROTO_FILEGEN: /* statistics (stats) */
stats_control = value;
break;
/*
* tos command - arguments are double, sometimes cast to int
*/
case PROTO_BEACON: /* manycast beacon (beacon) */
sys_beacon = (int)dvalue;
break;
case PROTO_BROADDELAY: /* default broadcast delay (bdelay) */
sys_bdelay = dvalue;
break;
case PROTO_CEILING: /* stratum ceiling (ceiling) */
sys_ceiling = (int)dvalue;
break;
case PROTO_COHORT: /* cohort switch (cohort) */
sys_cohort = (int)dvalue;
break;
case PROTO_FLOOR: /* stratum floor (floor) */
sys_floor = (int)dvalue;
break;
case PROTO_MAXCLOCK: /* maximum candidates (maxclock) */
sys_maxclock = (int)dvalue;
break;
case PROTO_MAXDIST: /* select threshold (maxdist) */
sys_maxdist = dvalue;
break;
case PROTO_CALLDELAY: /* modem call delay (mdelay) */
break; /* NOT USED */
case PROTO_MINCLOCK: /* minimum candidates (minclock) */
sys_minclock = (int)dvalue;
break;
case PROTO_MINDISP: /* minimum distance (mindist) */
sys_mindisp = dvalue;
break;
case PROTO_MINSANE: /* minimum survivors (minsane) */
sys_minsane = (int)dvalue;
break;
case PROTO_ORPHAN: /* orphan stratum (orphan) */
sys_orphan = (int)dvalue;
break;
case PROTO_ADJ: /* tick increment (tick) */
sys_tick = dvalue;
break;
/*
* Miscellaneous commands
*/
case PROTO_MULTICAST_ADD: /* add group address */
if (svalue != NULL)
io_multicast_add(svalue);
sys_bclient = 1;
break;
case PROTO_MULTICAST_DEL: /* delete group address */
if (svalue != NULL)
io_multicast_del(svalue);
break;
default:
msyslog(LOG_NOTICE,
"proto: unsupported option %d", item);
}
}
/*
* proto_clr_stats - clear protocol stat counters
*/
void
proto_clr_stats(void)
{
sys_stattime = current_time;
sys_received = 0;
sys_processed = 0;
sys_newversion = 0;
sys_oldversion = 0;
sys_declined = 0;
sys_restricted = 0;
sys_badlength = 0;
sys_badauth = 0;
sys_limitrejected = 0;
}
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