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freebsd-dev/contrib/ntp/ntpd/ntp_proto.c
Cy Schubert 767173cec2 MFV r362565: 
Update 4.2.8p14 --> 4.2.8p15

Summary: Systems that use a CMAC algorithm in ntp.keys will not release
a bit of memory on each packet that uses a CMAC keyid, eventually causing
ntpd to run out of memory and fail. The CMAC cleanup from
https://bugs.ntp.org/3447, part of ntp-4.2.8p11, introduced a bug whereby
the CMAC data structure was no longer completely removed.

MFC after:	3 days
Security:	NTP Bug 3661
2020-06-24 01:51:05 +00:00

5423 lines
151 KiB
C
Raw Blame History

/*
* ntp_proto.c - NTP version 4 protocol machinery
*
* ATTENTION: Get approval from Harlan on all changes to this file!
* (Harlan will be discussing these changes with Dave Mills.)
*
*/
#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 "ntp_leapsec.h"
#include "ntp_psl.h"
#include "refidsmear.h"
#include "lib_strbuf.h"
#include <stdio.h>
#ifdef HAVE_LIBSCF_H
#include <libscf.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
/* [Bug 3031] define automatic broadcastdelay cutoff preset */
#ifndef BDELAY_DEFAULT
# define BDELAY_DEFAULT (-0.050)
#endif
#define SRVFUZ_SHIFT 6 /* 64 seconds */
#define SRVRSP_FUZZ(x) \
do { \
x.l_uf &= 0; \
x.l_ui &= ~((1 << SRVFUZ_SHIFT) - 1U); \
} while(0)
/*
* This macro defines the authentication state. If x is 1 authentication
* is required; otherwise it is optional.
*/
#define AUTH(x, y) ((x) ? (y) == AUTH_OK \
: (y) == AUTH_OK || (y) == AUTH_NONE)
typedef enum
auth_state {
AUTH_UNKNOWN = -1, /* Unknown */
AUTH_NONE, /* authentication not required */
AUTH_OK, /* authentication OK */
AUTH_ERROR, /* authentication error */
AUTH_CRYPTO /* crypto_NAK */
} auth_code;
/*
* Set up Kiss Code values
*/
typedef enum
kiss_codes {
NOKISS, /* No Kiss Code */
RATEKISS, /* Rate limit Kiss Code */
DENYKISS, /* Deny Kiss */
RSTRKISS, /* Restricted Kiss */
XKISS /* Experimental Kiss */
} kiss_code;
typedef enum
nak_error_codes {
NONAK, /* No NAK seen */
INVALIDNAK, /* NAK cannot be used */
VALIDNAK /* NAK is valid */
} nak_code;
/*
* traffic shaping parameters
*/
#define NTP_IBURST 6 /* packets in iburst */
#define RESP_DELAY 1 /* refclock burst delay (s) */
/*
* pool soliciting restriction duration (s)
*/
#define POOL_SOLICIT_WINDOW 8
/*
* flag bits propagated from pool to individual peers
*/
#define POOL_FLAG_PMASK (FLAG_IBURST | FLAG_NOSELECT)
/*
* peer_select groups statistics for a peer used by clock_select() and
* clock_cluster().
*/
typedef struct peer_select_tag {
struct peer * peer;
double synch; /* sync distance */
double error; /* jitter */
double seljit; /* selection jitter */
} peer_select;
/*
* System variables are declared here. Unless specified otherwise, all
* times are in seconds.
*/
u_char sys_leap; /* system leap indicator, use set_sys_leap() to change this */
u_char xmt_leap; /* leap indicator sent in client requests, set up by set_sys_leap() */
u_char sys_stratum; /* system stratum */
s_char sys_precision; /* local clock precision (log2 s) */
double sys_rootdelay; /* roundtrip delay to root (primary source) */
double sys_rootdisp; /* dispersion to root (primary source) */
double prev_rootdisp; /* previous root dispersion */
double p2_rootdisp; /* previous previous root dispersion */
u_int32 sys_refid; /* reference id (network byte order) */
l_fp sys_reftime; /* last update time */
l_fp prev_reftime; /* previous sys_reftime */
l_fp p2_reftime; /* previous previous sys_reftime */
u_long prev_time; /* "current_time" when saved prev_time */
u_long p2_time; /* previous prev_time */
struct peer *sys_peer; /* current peer */
#ifdef LEAP_SMEAR
struct leap_smear_info leap_smear;
#endif
int leap_sec_in_progress;
/*
* 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 */
static int leap_vote_ins; /* leap consensus for insert */
static int leap_vote_del; /* leap consensus for delete */
keyid_t sys_private; /* private value for session seed */
int sys_manycastserver; /* respond to manycast client pkts */
int ntp_mode7; /* respond to ntpdc (mode7) */
int peer_ntpdate; /* active peers in ntpdate mode */
int sys_survivors; /* truest of the truechimers */
char *sys_ident = NULL; /* identity scheme */
/*
* TOS and multicast mapping stuff
*/
int sys_floor = 0; /* cluster stratum floor */
u_char sys_bcpollbstep = 0; /* Broadcast Poll backstep gate */
int sys_ceiling = STRATUM_UNSPEC - 1; /* 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_orphwait = NTP_ORPHWAIT; /* orphan wait */
int sys_beacon = BEACON; /* manycast beacon interval */
u_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 */
/*
* Mechanism knobs: how soon do we peer_clear() or unpeer()?
*
* The default way is "on-receipt". If this was a packet from a
* well-behaved source, on-receipt will offer the fastest recovery.
* If this was from a DoS attack, the default way makes it easier
* for a bad-guy to DoS us. So look and see what bites you harder
* and choose according to your environment.
*/
int peer_clear_digest_early = 1; /* bad digest (TEST5) and Autokey */
int unpeer_crypto_early = 1; /* bad crypto (TEST9) */
int unpeer_crypto_nak_early = 1; /* crypto_NAK (TEST5) */
int unpeer_digest_early = 1; /* bad digest (TEST5) */
int dynamic_interleave = DYNAMIC_INTERLEAVE; /* Bug 2978 mitigation */
int kiss_code_check(u_char hisleap, u_char hisstratum, u_char hismode, u_int32 refid);
nak_code valid_NAK (struct peer *peer, struct recvbuf *rbufp, u_char hismode);
static double root_distance (struct peer *);
static void clock_combine (peer_select *, int, int);
static void peer_xmit (struct peer *);
static void fast_xmit (struct recvbuf *, int, keyid_t, int);
static void pool_xmit (struct peer *);
static void clock_update (struct peer *);
static void measure_precision(void);
static double measure_tick_fuzz(void);
static int local_refid (struct peer *);
static int peer_unfit (struct peer *);
#ifdef AUTOKEY
static int group_test (char *, char *);
#endif /* AUTOKEY */
#ifdef WORKER
void pool_name_resolved (int, int, void *, const char *,
const char *, const struct addrinfo *,
const struct addrinfo *);
#endif /* WORKER */
const char * amtoa (int am);
void
set_sys_leap(
u_char new_sys_leap
)
{
sys_leap = new_sys_leap;
xmt_leap = sys_leap;
/*
* Under certain conditions we send faked leap bits to clients, so
* eventually change xmt_leap below, but never change LEAP_NOTINSYNC.
*/
if (xmt_leap != LEAP_NOTINSYNC) {
if (leap_sec_in_progress) {
/* always send "not sync" */
xmt_leap = LEAP_NOTINSYNC;
}
#ifdef LEAP_SMEAR
else {
/*
* If leap smear is enabled in general we must
* never send a leap second warning to clients,
* so make sure we only send "in sync".
*/
if (leap_smear.enabled)
xmt_leap = LEAP_NOWARNING;
}
#endif /* LEAP_SMEAR */
}
}
/*
* Kiss Code check
*/
int
kiss_code_check(
u_char hisleap,
u_char hisstratum,
u_char hismode,
u_int32 refid
)
{
if ( hismode == MODE_SERVER
&& hisleap == LEAP_NOTINSYNC
&& hisstratum == STRATUM_UNSPEC) {
if(memcmp(&refid,"RATE", 4) == 0) {
return (RATEKISS);
} else if(memcmp(&refid,"DENY", 4) == 0) {
return (DENYKISS);
} else if(memcmp(&refid,"RSTR", 4) == 0) {
return (RSTRKISS);
} else if(memcmp(&refid,"X", 1) == 0) {
return (XKISS);
}
}
return (NOKISS);
}
/*
* Check that NAK is valid
*/
nak_code
valid_NAK(
struct peer *peer,
struct recvbuf *rbufp,
u_char hismode
)
{
int base_packet_length = MIN_V4_PKT_LEN;
int remainder_size;
struct pkt * rpkt;
int keyid;
l_fp p_org; /* origin timestamp */
const l_fp * myorg; /* selected peer origin */
/*
* Check to see if there is something beyond the basic packet
*/
if (rbufp->recv_length == base_packet_length) {
return NONAK;
}
remainder_size = rbufp->recv_length - base_packet_length;
/*
* Is this a potential NAK?
*/
if (remainder_size != 4) {
return NONAK;
}
/*
* Only server responses can contain NAK's
*/
if (hismode != MODE_SERVER &&
hismode != MODE_ACTIVE &&
hismode != MODE_PASSIVE
) {
return INVALIDNAK;
}
/*
* Make sure that the extra field in the packet is all zeros
*/
rpkt = &rbufp->recv_pkt;
keyid = ntohl(((u_int32 *)rpkt)[base_packet_length / 4]);
if (keyid != 0) {
return INVALIDNAK;
}
/*
* During the first few packets of the autokey dance there will
* not (yet) be a keyid, but in this case FLAG_SKEY is set.
* So the NAK is invalid if either there's no peer, or
* if the keyid is 0 and FLAG_SKEY is not set.
*/
if (!peer || (!peer->keyid && !(peer->flags & FLAG_SKEY))) {
return INVALIDNAK;
}
/*
* The ORIGIN must match, or this cannot be a valid NAK, either.
*/
if (FLAG_LOOPNONCE & peer->flags) {
myorg = &peer->nonce;
} else {
if (peer->flip > 0) {
myorg = &peer->borg;
} else {
myorg = &peer->aorg;
}
}
NTOHL_FP(&rpkt->org, &p_org);
if (L_ISZERO(&p_org) ||
L_ISZERO( myorg) ||
!L_ISEQU(&p_org, myorg)) {
return INVALIDNAK;
}
/* If we ever passed all that checks, we should be safe. Well,
* as safe as we can ever be with an unauthenticated crypto-nak.
*/
return VALIDNAK;
}
/*
* transmit - transmit procedure called by poll timeout
*/
void
transmit(
struct peer *peer /* peer structure pointer */
)
{
u_char hpoll;
/*
* The polling state machine. There are two kinds of machines,
* those that never expect a reply (broadcast and manycast
* server modes) and those that do (all other modes). The dance
* is intricate...
*/
hpoll = peer->hpoll;
/*
* If we haven't received anything (even if unsync) since last
* send, reset ppoll.
*/
if (peer->outdate > peer->timelastrec && !peer->reach)
peer->ppoll = peer->maxpoll;
/*
* In broadcast mode the poll interval is never changed from
* minpoll.
*/
if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) {
peer->outdate = current_time;
poll_update(peer, hpoll, 0);
if (sys_leap != LEAP_NOTINSYNC)
peer_xmit(peer);
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 sys_minclock
* associations turn up. In this case additional better servers
* are dragged in and preempt the existing ones. Once every
* sys_beacon seconds we are to transmit unconditionally, but
* this code is not quite right -- peer->unreach counts polls
* and is being compared with sys_beacon, so the beacons happen
* every sys_beacon polls.
*/
if (peer->cast_flags & MDF_ACAST) {
peer->outdate = current_time;
poll_update(peer, hpoll, 0);
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++;
return;
}
/*
* Pool associations transmit unicast solicitations when there
* are less than a hard limit of 2 * sys_maxclock associations,
* and either less than sys_minclock survivors or less than
* sys_maxclock associations. The hard limit prevents unbounded
* growth in associations if the system clock or network quality
* result in survivor count dipping below sys_minclock often.
* This was observed testing with pool, where sys_maxclock == 12
* resulted in 60 associations without the hard limit. A
* similar hard limit on manycastclient ephemeral associations
* may be appropriate.
*/
if (peer->cast_flags & MDF_POOL) {
peer->outdate = current_time;
poll_update(peer, hpoll, 0);
if ( (peer_associations <= 2 * sys_maxclock)
&& ( peer_associations < sys_maxclock
|| sys_survivors < sys_minclock))
pool_xmit(peer);
return;
}
/*
* In unicast modes the dance is much more intricate. It is
* designed 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) {
/*
* Here the peer is unreachable. If it was
* previously reachable raise a trap. Send a
* burst if enabled.
*/
clock_filter(peer, 0., 0., MAXDISPERSE);
if (oreach) {
peer_unfit(peer);
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. Reset unreach
* for persistent and ephemeral associations.
* Unreach is also reset for survivors in
* clock_select().
*/
hpoll = sys_poll;
if (!(peer->flags & FLAG_PREEMPT))
peer->unreach = 0;
if ( (peer->flags & FLAG_BURST)
&& peer->retry == 0
&& !peer_unfit(peer))
peer->retry = NTP_RETRY;
}
/*
* Watch for timeout. If ephemeral, toss the rascal;
* otherwise, bump the poll interval. Note the
* poll_update() routine will clamp it to maxpoll.
* If preemptible and we have more peers than maxclock,
* and this peer has the minimum score of preemptibles,
* demobilize.
*/
if (peer->unreach >= NTP_UNREACH) {
hpoll++;
/* ephemeral: no FLAG_CONFIG nor FLAG_PREEMPT */
if (!(peer->flags & (FLAG_CONFIG | FLAG_PREEMPT))) {
report_event(PEVNT_RESTART, peer, "timeout");
peer_clear(peer, "TIME");
unpeer(peer);
return;
}
if ( (peer->flags & FLAG_PREEMPT)
&& (peer_associations > sys_maxclock)
&& score_all(peer)) {
report_event(PEVNT_RESTART, peer, "timeout");
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");
if (!msyslog_term)
printf(
"ntpd: no servers found\n");
exit (0);
}
}
}
}
if (peer->retry > 0)
peer->retry--;
/*
* Do not transmit if in broadcast client mode.
*/
poll_update(peer, hpoll, (peer->hmode == MODE_CLIENT));
if (peer->hmode != MODE_BCLIENT)
peer_xmit(peer);
return;
}
const char *
amtoa(
int am
)
{
char *bp;
switch(am) {
case AM_ERR: return "AM_ERR";
case AM_NOMATCH: return "AM_NOMATCH";
case AM_PROCPKT: return "AM_PROCPKT";
case AM_BCST: return "AM_BCST";
case AM_FXMIT: return "AM_FXMIT";
case AM_MANYCAST: return "AM_MANYCAST";
case AM_NEWPASS: return "AM_NEWPASS";
case AM_NEWBCL: return "AM_NEWBCL";
case AM_POSSBCL: return "AM_POSSBCL";
default:
LIB_GETBUF(bp);
snprintf(bp, LIB_BUFLENGTH, "AM_#%d", am);
return bp;
}
}
/*
* 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 */
u_char hisversion; /* packet version */
u_char hisleap; /* packet leap indicator */
u_char hismode; /* packet mode */
u_char hisstratum; /* packet stratum */
r4addr r4a; /* address restrictions */
u_short restrict_mask; /* restrict bits */
const char *hm_str; /* hismode string */
const char *am_str; /* association match string */
int kissCode = NOKISS; /* Kiss Code */
int has_mac; /* length of MAC field */
int authlen; /* offset of MAC field */
auth_code is_authentic = AUTH_UNKNOWN; /* Was AUTH_NONE */
nak_code crypto_nak_test; /* result of crypto-NAK check */
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 AUTOKEY
char hostname[NTP_MAXSTRLEN + 1];
char *groupname = NULL;
struct autokey *ap; /* autokey structure pointer */
int rval; /* cookie snatcher */
keyid_t pkeyid = 0, tkeyid = 0; /* key IDs */
#endif /* AUTOKEY */
#ifdef HAVE_NTP_SIGND
static unsigned char zero_key[16];
#endif /* HAVE_NTP_SIGND */
/*
* Note that there are many places we do not call record_raw_stats().
*
* We only want to call it *after* we've sent a response, or perhaps
* when we've decided to drop a packet.
*/
/*
* 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. Likewise the mimimum packet size
* of 2 bytes (for mode 6/7) must be checked first.
*/
sys_received++;
if (0 == SRCPORT(&rbufp->recv_srcadr) || rbufp->recv_length < 2) {
sys_badlength++;
return; /* bogus port / length */
}
restrictions(&rbufp->recv_srcadr, &r4a);
restrict_mask = r4a.rflags;
pkt = &rbufp->recv_pkt;
hisversion = PKT_VERSION(pkt->li_vn_mode);
hismode = (int)PKT_MODE(pkt->li_vn_mode);
if (restrict_mask & RES_IGNORE) {
DPRINTF(2, ("receive: drop: RES_IGNORE\n"));
sys_restricted++;
return; /* ignore everything */
}
if (hismode == MODE_PRIVATE) {
if (!ntp_mode7 || (restrict_mask & RES_NOQUERY)) {
DPRINTF(2, ("receive: drop: RES_NOQUERY\n"));
sys_restricted++;
return; /* no query private */
}
process_private(rbufp, ((restrict_mask &
RES_NOMODIFY) == 0));
return;
}
if (hismode == MODE_CONTROL) {
if (restrict_mask & RES_NOQUERY) {
DPRINTF(2, ("receive: drop: RES_NOQUERY\n"));
sys_restricted++;
return; /* no query control */
}
process_control(rbufp, restrict_mask);
return;
}
if (restrict_mask & RES_DONTSERVE) {
DPRINTF(2, ("receive: drop: RES_DONTSERVE\n"));
sys_restricted++;
return; /* no time serve */
}
/* If we arrive here, we should have a standard NTP packet. We
* check that the minimum size is available and fetch some more
* items from the packet once we can be sure they are indeed
* there.
*/
if (rbufp->recv_length < LEN_PKT_NOMAC) {
sys_badlength++;
return; /* bogus length */
}
hisleap = PKT_LEAP(pkt->li_vn_mode);
hisstratum = PKT_TO_STRATUM(pkt->stratum);
INSIST(0 != hisstratum); /* paranoia check PKT_TO_STRATUM result */
DPRINTF(1, ("receive: at %ld %s<-%s ippeerlimit %d mode %d iflags %s "
"restrict %s org %#010x.%08x xmt %#010x.%08x\n",
current_time, stoa(&rbufp->dstadr->sin),
stoa(&rbufp->recv_srcadr), r4a.ippeerlimit, hismode,
build_iflags(rbufp->dstadr->flags),
build_rflags(restrict_mask),
ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
/*
* This is for testing. If restricted drop ten percent of
* surviving packets.
*/
if (restrict_mask & RES_FLAKE) {
if ((double)ntp_random() / 0x7fffffff < .1) {
DPRINTF(2, ("receive: drop: RES_FLAKE\n"));
sys_restricted++;
return; /* no flakeway */
}
}
/*
** Format Layer Checks
**
** Validate the packet format. The packet size, packet header,
** and any extension field lengths are checked. We identify
** the beginning of the MAC, to identify the upper limit of
** of the hash computation.
**
** In case of a format layer check violation, the packet is
** discarded with no further processing.
*/
/*
* 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 {
DPRINTF(2, ("receive: drop: RES_VERSION\n"));
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 {
DPRINTF(2, ("receive: drop: MODE_UNSPEC\n"));
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.
*
* Note the above description is lame. We should/could also check
* the two bytes that make up the EF type and subtype, and then
* check the two bytes that tell us the EF length. A legacy MAC
* has a 4 byte keyID, and for conforming symmetric keys its value
* must be <= 64k, meaning the top two bytes will always be zero.
* Since the EF Type of 0 is reserved/unused, there's no way a
* conforming legacy MAC could ever be misinterpreted as an EF.
*
* There is more, but this isn't the place to document it.
*/
authlen = LEN_PKT_NOMAC;
has_mac = rbufp->recv_length - authlen;
while (has_mac > 0) {
u_int32 len;
#ifdef AUTOKEY
u_int32 hostlen;
struct exten *ep;
#endif /*AUTOKEY */
if (has_mac % 4 != 0 || has_mac < (int)MIN_MAC_LEN) {
DPRINTF(2, ("receive: drop: bad post-packet length\n"));
sys_badlength++;
return; /* bad length */
}
/*
* This next test is clearly wrong - it needlessly
* prohibits short EFs (which don't yet exist)
*/
if (has_mac <= (int)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
|| (int)len + authlen > rbufp->recv_length) {
DPRINTF(2, ("receive: drop: bad EF length\n"));
sys_badlength++;
return; /* bad length */
}
#ifdef AUTOKEY
/*
* Extract calling group name for later. If
* sys_groupname is non-NULL, there must be
* a group name provided to elicit a response.
*/
if ( (opcode & 0x3fff0000) == CRYPTO_ASSOC
&& sys_groupname != NULL) {
ep = (struct exten *)&((u_int32 *)pkt)[authlen / 4];
hostlen = ntohl(ep->vallen);
if ( hostlen >= sizeof(hostname)
|| hostlen > len -
offsetof(struct exten, pkt)) {
DPRINTF(2, ("receive: drop: bad autokey hostname length\n"));
sys_badlength++;
return; /* bad length */
}
memcpy(hostname, &ep->pkt, hostlen);
hostname[hostlen] = '\0';
groupname = strchr(hostname, '@');
if (groupname == NULL) {
DPRINTF(2, ("receive: drop: empty autokey groupname\n"));
sys_declined++;
return;
}
groupname++;
}
#endif /* AUTOKEY */
authlen += len;
has_mac -= len;
}
}
/*
* If has_mac is < 0 we had a malformed packet.
*/
if (has_mac < 0) {
DPRINTF(2, ("receive: drop: post-packet under-read\n"));
sys_badlength++;
return; /* bad length */
}
/*
** Packet Data Verification Layer
**
** This layer verifies the packet data content. If
** authentication is required, a MAC must be present.
** If a MAC is present, it must validate.
** Crypto-NAK? Look - a shiny thing!
**
** If authentication fails, we're done.
*/
/*
* If authentication is explicitly required, a MAC must be present.
*/
if (restrict_mask & RES_DONTTRUST && has_mac == 0) {
DPRINTF(2, ("receive: drop: RES_DONTTRUST\n"));
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.
* RES_LIMITED and RES_KOD will be cleared in the returned
* restrict_mask unless one or both actions are warranted.
*/
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) {
if (MODE_SERVER == hismode) {
DPRINTF(1, ("Possibly self-induced rate limiting of MODE_SERVER from %s\n",
stoa(&rbufp->recv_srcadr)));
} else {
DPRINTF(2, ("receive: drop: RES_KOD\n"));
}
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
* digest 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);
hm_str = modetoa(hismode);
am_str = amtoa(retcode);
/*
* 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.
*/
crypto_nak_test = valid_NAK(peer, rbufp, hismode);
/*
* Drop any invalid crypto-NAKs
*/
if (crypto_nak_test == INVALIDNAK) {
report_event(PEVNT_AUTH, peer, "Invalid_NAK");
if (0 != peer) {
peer->badNAK++;
}
msyslog(LOG_ERR, "Invalid-NAK error at %ld %s<-%s",
current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr));
return;
}
if (has_mac == 0) {
restrict_mask &= ~RES_MSSNTP;
is_authentic = AUTH_NONE; /* not required */
DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org %#010x.%08x xmt %#010x.%08x NOMAC\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
authlen,
ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
} else if (crypto_nak_test == VALIDNAK) {
restrict_mask &= ~RES_MSSNTP;
is_authentic = AUTH_CRYPTO; /* crypto-NAK */
DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org %#010x.%08x xmt %#010x.%08x CRYPTONAK\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
skeyid, authlen + has_mac, is_authentic,
ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
#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;
DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org %#010x.%08x xmt %#010x.%08x SIGND\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
authlen,
ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
#endif /* HAVE_NTP_SIGND */
} else {
/*
* has_mac is not 0
* Not a VALID_NAK
* Not an MS-SNTP SIGND packet
*
* So there is a MAC here.
*/
restrict_mask &= ~RES_MSSNTP;
#ifdef AUTOKEY
/*
* 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 < (int)MAX_MD5_LEN) {
DPRINTF(2, ("receive: drop: MD5 digest too short\n"));
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_CHOOSE(&rbufp->recv_srcadr)) {
DPRINTF(2, ("receive: drop: BCAST from wildcard\n"));
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 > (int)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 /* AUTOKEY */
/*
* 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 AUTOKEY
if (crypto_flags && skeyid > NTP_MAXKEY)
authtrust(skeyid, 0);
#endif /* AUTOKEY */
DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org %#010x.%08x xmt %#010x.%08x MAC\n",
current_time, stoa(dstadr_sin),
stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
skeyid, authlen + has_mac, is_authentic,
ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
}
/*
* Bug 3454:
*
* Now come at this from a different perspective:
* - If we expect a MAC and it's not there, we drop it.
* - If we expect one keyID and get another, we drop it.
* - If we have a MAC ahd it hasn't been validated yet, try.
* - if the provided MAC doesn't validate, we drop it.
*
* There might be more to this.
*/
if (0 != peer && 0 != peer->keyid) {
/* Should we msyslog() any of these? */
/*
* This should catch:
* - no keyID where one is expected,
* - different keyID than what we expect.
*/
if (peer->keyid != skeyid) {
DPRINTF(2, ("receive: drop: Wanted keyID %d, got %d from %s\n",
peer->keyid, skeyid,
stoa(&rbufp->recv_srcadr)));
sys_restricted++;
return; /* drop: access denied */
}
/*
* if has_mac != 0 ...
* - If it has not yet been validated, do so.
* (under what circumstances might that happen?)
* - if missing or bad MAC, log and drop.
*/
if (0 != has_mac) {
if (is_authentic == AUTH_UNKNOWN) {
/* How can this happen? */
DPRINTF(2, ("receive: 3454 check: AUTH_UNKNOWN from %s\n",
stoa(&rbufp->recv_srcadr)));
if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen,
has_mac)) {
/* MAC invalid or not found */
is_authentic = AUTH_ERROR;
} else {
is_authentic = AUTH_OK;
}
}
if (is_authentic != AUTH_OK) {
DPRINTF(2, ("receive: drop: missing or bad MAC from %s\n",
stoa(&rbufp->recv_srcadr)));
sys_restricted++;
return; /* drop: access denied */
}
}
}
/**/
/*
** On-Wire Protocol Layer
**
** Verify protocol operations consistent with the on-wire protocol.
** The protocol discards bogus and duplicate packets as well as
** minimizes disruptions doe to protocol restarts and dropped
** packets. The operations are controlled by two timestamps:
** the transmit timestamp saved in the client state variables,
** and the origin timestamp in the server packet header. The
** comparison of these two timestamps is called the loopback test.
** The transmit timestamp functions as a nonce to verify that the
** response corresponds to the original request. The transmit
** timestamp also serves to discard replays of the most recent
** packet. Upon failure of either test, the packet is discarded
** with no further action.
*/
/*
* 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.
*/
DPRINTF(1, ("receive: MATCH_ASSOC dispatch: mode %d/%s:%s \n",
hismode, hm_str, am_str));
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.
*
* There are cases here where we do not call record_raw_stats().
*/
case AM_FXMIT:
/*
* If authentication OK, send a server reply; otherwise,
* send a crypto-NAK.
*/
if (!(rbufp->dstadr->flags & INT_MCASTOPEN)) {
/* HMS: would be nice to log FAST_XMIT|BADAUTH|RESTRICTED */
record_raw_stats(&rbufp->recv_srcadr,
&rbufp->dstadr->sin,
&p_org, &p_rec, &p_xmt, &rbufp->recv_time,
PKT_LEAP(pkt->li_vn_mode),
PKT_VERSION(pkt->li_vn_mode),
PKT_MODE(pkt->li_vn_mode),
PKT_TO_STRATUM(pkt->stratum),
pkt->ppoll,
pkt->precision,
FPTOD(NTOHS_FP(pkt->rootdelay)),
FPTOD(NTOHS_FP(pkt->rootdisp)),
pkt->refid,
rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten);
if (AUTH(restrict_mask & RES_DONTTRUST,
is_authentic)) {
/* Bug 3596: Do we want to fuzz the reftime? */
fast_xmit(rbufp, MODE_SERVER, skeyid,
restrict_mask);
} else if (is_authentic == AUTH_ERROR) {
/* Bug 3596: Do we want to fuzz the reftime? */
fast_xmit(rbufp, MODE_SERVER, 0,
restrict_mask);
sys_badauth++;
} else {
DPRINTF(2, ("receive: AM_FXMIT drop: !mcast restricted\n"));
sys_restricted++;
}
return; /* hooray */
}
/*
* This must be manycast. Do not respond if not
* configured as a manycast server.
*/
if (!sys_manycastserver) {
DPRINTF(2, ("receive: AM_FXMIT drop: Not manycastserver\n"));
sys_restricted++;
return; /* not enabled */
}
#ifdef AUTOKEY
/*
* Do not respond if not the same group.
*/
if (group_test(groupname, NULL)) {
DPRINTF(2, ("receive: AM_FXMIT drop: empty groupname\n"));
sys_declined++;
return;
}
#endif /* AUTOKEY */
/*
* 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 + 1
|| (!sys_cohort && sys_stratum == hisstratum + 1)
|| rbufp->dstadr->addr_refid == pkt->refid) {
DPRINTF(2, ("receive: sys leap: %0x, sys_stratum %d > hisstratum+1 %d, !sys_cohort %d && sys_stratum == hisstratum+1, loop refid %#x == pkt refid %#x\n", sys_leap, sys_stratum, hisstratum + 1, !sys_cohort, rbufp->dstadr->addr_refid, pkt->refid));
DPRINTF(2, ("receive: AM_FXMIT drop: LEAP_NOTINSYNC || stratum || loop\n"));
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)) {
record_raw_stats(&rbufp->recv_srcadr,
&rbufp->dstadr->sin,
&p_org, &p_rec, &p_xmt, &rbufp->recv_time,
PKT_LEAP(pkt->li_vn_mode),
PKT_VERSION(pkt->li_vn_mode),
PKT_MODE(pkt->li_vn_mode),
PKT_TO_STRATUM(pkt->stratum),
pkt->ppoll,
pkt->precision,
FPTOD(NTOHS_FP(pkt->rootdelay)),
FPTOD(NTOHS_FP(pkt->rootdisp)),
pkt->refid,
rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten);
/* Bug 3596: Do we want to fuzz the reftime? */
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 (for
* manycastclient) or to a unicast address (for pool). 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 manycastclient or pool
* association is found, we mobilize a client association and
* copy pertinent variables from the manycastclient or pool
* 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.
*
* There are cases here where we do not call record_raw_stats().
*/
case AM_MANYCAST:
#ifdef AUTOKEY
/*
* Do not respond if not the same group.
*/
if (group_test(groupname, NULL)) {
DPRINTF(2, ("receive: AM_MANYCAST drop: empty groupname\n"));
sys_declined++;
return;
}
#endif /* AUTOKEY */
if ((peer2 = findmanycastpeer(rbufp)) == NULL) {
DPRINTF(2, ("receive: AM_MANYCAST drop: No manycast peer\n"));
sys_restricted++;
return; /* not enabled */
}
if (!AUTH( (!(peer2->cast_flags & MDF_POOL)
&& sys_authenticate)
|| (restrict_mask & (RES_NOPEER |
RES_DONTTRUST)), is_authentic)
/* MC: RES_NOEPEER? */
) {
DPRINTF(2, ("receive: AM_MANYCAST drop: bad auth || (NOPEER|DONTTRUST)\n"));
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) {
DPRINTF(2, ("receive: AM_MANYCAST drop: unsync/stratum\n"));
sys_declined++;
return; /* no help */
}
peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr,
r4a.ippeerlimit, MODE_CLIENT, hisversion,
peer2->minpoll, peer2->maxpoll,
(FLAG_PREEMPT | (POOL_FLAG_PMASK & peer2->flags)),
(MDF_UCAST | MDF_UCLNT), 0, skeyid, sys_ident);
if (NULL == peer) {
DPRINTF(2, ("receive: AM_MANYCAST drop: duplicate\n"));
sys_declined++;
return; /* ignore duplicate */
}
/*
* After each ephemeral pool association is spun,
* accelerate the next poll for the pool solicitor so
* the pool will fill promptly.
*/
if (peer2->cast_flags & MDF_POOL)
peer2->nextdate = current_time + 1;
/*
* Further processing of the solicitation response would
* simply detect its origin timestamp as bogus for the
* brand-new association (it matches the prototype
* association) and tinker with peer->nextdate delaying
* first sync.
*/
return; /* solicitation response handled */
/*
* 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.
*
* There are cases here where we do not call record_raw_stats().
*/
case AM_NEWBCL:
#ifdef AUTOKEY
/*
* Do not respond if not the same group.
*/
if (group_test(groupname, sys_ident)) {
DPRINTF(2, ("receive: AM_NEWBCL drop: groupname mismatch\n"));
sys_declined++;
return;
}
#endif /* AUTOKEY */
if (sys_bclient == 0) {
DPRINTF(2, ("receive: AM_NEWBCL drop: not a bclient\n"));
sys_restricted++;
return; /* not enabled */
}
if (!AUTH(sys_authenticate | (restrict_mask &
(RES_NOPEER | RES_DONTTRUST)), is_authentic)
/* NEWBCL: RES_NOEPEER? */
) {
DPRINTF(2, ("receive: AM_NEWBCL drop: AUTH failed\n"));
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) {
DPRINTF(2, ("receive: AM_NEWBCL drop: Unsync or bad stratum\n"));
sys_declined++;
return; /* no help */
}
#ifdef AUTOKEY
/*
* Do not respond if Autokey and the opcode is not a
* CRYPTO_ASSOC response with association ID.
*/
if ( crypto_flags && skeyid > NTP_MAXKEY
&& (opcode & 0xffff0000) != (CRYPTO_ASSOC | CRYPTO_RESP)) {
DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not CRYPTO_ASSOC\n"));
sys_declined++;
return; /* protocol error */
}
#endif /* AUTOKEY */
/*
* 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 > 0.0) {
#ifdef AUTOKEY
/*
* If a two-way exchange is not possible,
* neither is Autokey.
*/
if (crypto_flags && skeyid > NTP_MAXKEY) {
sys_restricted++;
DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not 2-way\n"));
return; /* no autokey */
}
#endif /* AUTOKEY */
/*
* Do not execute the volley. Start out in
* broadcast client mode.
*/
peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep,
r4a.ippeerlimit, MODE_BCLIENT, hisversion,
pkt->ppoll, pkt->ppoll,
FLAG_PREEMPT, MDF_BCLNT, 0, skeyid, sys_ident);
if (NULL == peer) {
DPRINTF(2, ("receive: AM_NEWBCL drop: duplicate\n"));
sys_restricted++;
return; /* ignore duplicate */
} else {
peer->delay = sys_bdelay;
peer->bxmt = p_xmt;
}
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, NULL, match_ep,
r4a.ippeerlimit, MODE_CLIENT, hisversion,
pkt->ppoll, pkt->ppoll,
FLAG_BC_VOL | FLAG_IBURST | FLAG_PREEMPT, MDF_BCLNT,
0, skeyid, sys_ident);
if (NULL == peer) {
DPRINTF(2, ("receive: AM_NEWBCL drop: empty newpeer() failed\n"));
sys_restricted++;
return; /* ignore duplicate */
}
peer->bxmt = p_xmt;
#ifdef AUTOKEY
if (skeyid > NTP_MAXKEY)
crypto_recv(peer, rbufp);
#endif /* AUTOKEY */
return; /* hooray */
/*
* This is the first packet received from a potential ephemeral
* symmetric active peer. First, deal with broken Windows clients.
* Then, if NOEPEER is enabled, drop it. If the packet meets our
* authenticty requirements and is the first he sent, mobilize
* a passive association.
* Otherwise, kiss the frog.
*
* There are cases here where we do not call record_raw_stats().
*/
case AM_NEWPASS:
DEBUG_REQUIRE(MODE_ACTIVE == hismode);
#ifdef AUTOKEY
/*
* Do not respond if not the same group.
*/
if (group_test(groupname, sys_ident)) {
DPRINTF(2, ("receive: AM_NEWPASS drop: Autokey group mismatch\n"));
sys_declined++;
return;
}
#endif /* AUTOKEY */
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 */
}
/* HMS: Why is this next set of lines a feature? */
if (is_authentic == AUTH_ERROR) {
fast_xmit(rbufp, MODE_PASSIVE, 0,
restrict_mask);
sys_restricted++;
return;
}
if (restrict_mask & RES_NOEPEER) {
DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n"));
sys_declined++;
return;
}
/* [Bug 2941]
* If we got here, the packet isn't part of an
* existing association, either isn't correctly
* authenticated or it is but we are refusing
* ephemeral peer requests, and it didn't meet
* either of the previous two special cases so we
* should just drop it on the floor. For example,
* crypto-NAKs (is_authentic == AUTH_CRYPTO)
* will make it this far. This is just
* debug-printed and not logged to avoid log
* flooding.
*/
DPRINTF(2, ("receive: at %ld refusing to mobilize passive association"
" with unknown peer %s mode %d/%s:%s keyid %08x len %d auth %d\n",
current_time, stoa(&rbufp->recv_srcadr),
hismode, hm_str, am_str, skeyid,
(authlen + has_mac), is_authentic));
sys_declined++;
return;
}
if (restrict_mask & RES_NOEPEER) {
DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n"));
sys_declined++;
return;
}
/*
* Do not respond if synchronized and if stratum is
* 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. It also means
* we will spin an ephemeral association in response to
* MODE_ACTIVE KoDs, which will time out eventually.
*/
if ( hisleap != LEAP_NOTINSYNC
&& (hisstratum < sys_floor || hisstratum >= sys_ceiling)) {
DPRINTF(2, ("receive: AM_NEWPASS drop: Remote stratum (%d) out of range\n",
hisstratum));
sys_declined++;
return; /* no help */
}
/*
* The message is correctly authenticated and allowed.
* Mobilize a symmetric passive association, if we won't
* exceed the ippeerlimit.
*/
if ((peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr,
r4a.ippeerlimit, MODE_PASSIVE, hisversion,
pkt->ppoll, NTP_MAXDPOLL, 0, MDF_UCAST, 0,
skeyid, sys_ident)) == NULL) {
DPRINTF(2, ("receive: AM_NEWPASS drop: newpeer() failed\n"));
sys_declined++;
return; /* ignore duplicate */
}
break;
/*
* Process regular packet. Nothing special.
*
* There are cases here where we do not call record_raw_stats().
*/
case AM_PROCPKT:
#ifdef AUTOKEY
/*
* Do not respond if not the same group.
*/
if (group_test(groupname, peer->ident)) {
DPRINTF(2, ("receive: AM_PROCPKT drop: Autokey group mismatch\n"));
sys_declined++;
return;
}
#endif /* AUTOKEY */
if (MODE_BROADCAST == hismode) {
int bail = 0;
l_fp tdiff;
u_long deadband;
DPRINTF(2, ("receive: PROCPKT/BROADCAST: prev pkt %ld seconds ago, ppoll: %d, %d secs\n",
(current_time - peer->timelastrec),
peer->ppoll, (1 << peer->ppoll)
));
/* Things we can check:
*
* Did the poll interval change?
* Is the poll interval in the packet in-range?
* Did this packet arrive too soon?
* Is the timestamp in this packet monotonic
* with respect to the previous packet?
*/
/* This is noteworthy, not error-worthy */
if (pkt->ppoll != peer->ppoll) {
msyslog(LOG_INFO, "receive: broadcast poll from %s changed from %u to %u",
stoa(&rbufp->recv_srcadr),
peer->ppoll, pkt->ppoll);
}
/* This is error-worthy */
if ( pkt->ppoll < peer->minpoll
|| pkt->ppoll > peer->maxpoll) {
msyslog(LOG_INFO, "receive: broadcast poll of %u from %s is out-of-range (%d to %d)!",
pkt->ppoll, stoa(&rbufp->recv_srcadr),
peer->minpoll, peer->maxpoll);
++bail;
}
/* too early? worth an error, too!
*
* [Bug 3113] Ensure that at least one poll
* interval has elapsed since the last **clean**
* packet was received. We limit the check to
* **clean** packets to prevent replayed packets
* and incorrectly authenticated packets, which
* we'll discard, from being used to create a
* denial of service condition.
*/
deadband = (1u << pkt->ppoll);
if (FLAG_BC_VOL & peer->flags)
deadband -= 3; /* allow greater fuzz after volley */
if ((current_time - peer->timereceived) < deadband) {
msyslog(LOG_INFO, "receive: broadcast packet from %s arrived after %lu, not %lu seconds!",
stoa(&rbufp->recv_srcadr),
(current_time - peer->timereceived),
deadband);
++bail;
}
/* Alert if time from the server is non-monotonic.
*
* [Bug 3114] is about Broadcast mode replay DoS.
*
* Broadcast mode *assumes* a trusted network.
* Even so, it's nice to be robust in the face
* of attacks.
*
* If we get an authenticated broadcast packet
* with an "earlier" timestamp, it means one of
* two things:
*
* - the broadcast server had a backward step.
*
* - somebody is trying a replay attack.
*
* deadband: By default, we assume the broadcast
* network is trustable, so we take our accepted
* broadcast packets as we receive them. But
* some folks might want to take additional poll
* delays before believing a backward step.
*/
if (sys_bcpollbstep) {
/* pkt->ppoll or peer->ppoll ? */
deadband = (1u << pkt->ppoll)
* sys_bcpollbstep + 2;
} else {
deadband = 0;
}
if (L_ISZERO(&peer->bxmt)) {
tdiff.l_ui = tdiff.l_uf = 0;
} else {
tdiff = p_xmt;
L_SUB(&tdiff, &peer->bxmt);
}
if ( tdiff.l_i < 0
&& (current_time - peer->timereceived) < deadband)
{
msyslog(LOG_INFO, "receive: broadcast packet from %s contains non-monotonic timestamp: %#010x.%08x -> %#010x.%08x",
stoa(&rbufp->recv_srcadr),
peer->bxmt.l_ui, peer->bxmt.l_uf,
p_xmt.l_ui, p_xmt.l_uf
);
++bail;
}
if (bail) {
DPRINTF(2, ("receive: AM_PROCPKT drop: bail\n"));
peer->timelastrec = current_time;
sys_declined++;
return;
}
}
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 legitimate and this packet an
* attempt to deny service, just ignore it.
*/
case AM_ERR:
DPRINTF(2, ("receive: AM_ERR drop.\n"));
sys_declined++;
return;
/*
* For everything else there is the bit bucket.
*/
default:
DPRINTF(2, ("receive: default drop.\n"));
sys_declined++;
return;
}
#ifdef AUTOKEY
/*
* 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))) {
DPRINTF(2, ("receive: drop: Autokey but wrong/bad auth\n"));
sys_badauth++;
return;
}
#endif /* AUTOKEY */
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.
*
* A KoD packet we pay attention to cannot have a 0 transmit
* timestamp.
*/
kissCode = kiss_code_check(hisleap, hisstratum, hismode, pkt->refid);
if (L_ISZERO(&p_xmt)) {
peer->flash |= TEST3; /* unsynch */
if (kissCode != NOKISS) { /* KoD packet */
peer->bogusorg++; /* for TEST2 or TEST3 */
msyslog(LOG_INFO,
"receive: Unexpected zero transmit timestamp in KoD from %s",
ntoa(&peer->srcadr));
return;
}
/*
* If the transmit timestamp duplicates our previous one, the
* packet is a replay. This prevents the bad guys from replaying
* the most recent packet, authenticated or not.
*/
} else if ( ((FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->nonce, &p_xmt))
|| (!(FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->xmt, &p_xmt))
) {
DPRINTF(2, ("receive: drop: Duplicate xmit\n"));
peer->flash |= TEST1; /* duplicate */
peer->oldpkt++;
return;
/*
* If this is a broadcast mode packet, make sure hisstratum
* is appropriate. Don't do anything else here - we wait to
* see if this is an interleave broadcast packet until after
* we've validated the MAC that SHOULD be provided.
*
* hisstratum cannot be 0 - see assertion above.
* If hisstratum is 15, then we'll advertise as UNSPEC but
* at least we'll be able to sync with the broadcast server.
*/
} else if (hismode == MODE_BROADCAST) {
/* 0 is unexpected too, and impossible */
if (STRATUM_UNSPEC <= hisstratum) {
/* Is this a ++sys_declined or ??? */
msyslog(LOG_INFO,
"receive: Unexpected stratum (%d) in broadcast from %s",
hisstratum, ntoa(&peer->srcadr));
return;
}
/*
* Basic KoD validation checking:
*
* KoD packets are a mixed-blessing. Forged KoD packets
* are DoS attacks. There are rare situations where we might
* get a valid KoD response, though. Since KoD packets are
* a special case that complicate the checks we do next, we
* handle the basic KoD checks here.
*
* Note that we expect the incoming KoD packet to have its
* (nonzero) org, rec, and xmt timestamps set to the xmt timestamp
* that we have previously sent out. Watch interleave mode.
*/
} else if (kissCode != NOKISS) {
DEBUG_INSIST(!L_ISZERO(&p_xmt));
if ( L_ISZERO(&p_org) /* We checked p_xmt above */
|| L_ISZERO(&p_rec)) {
peer->bogusorg++;
msyslog(LOG_INFO,
"receive: KoD packet from %s has a zero org or rec timestamp. Ignoring.",
ntoa(&peer->srcadr));
return;
}
if ( !L_ISEQU(&p_xmt, &p_org)
|| !L_ISEQU(&p_xmt, &p_rec)) {
peer->bogusorg++;
msyslog(LOG_INFO,
"receive: KoD packet from %s has inconsistent xmt/org/rec timestamps. Ignoring.",
ntoa(&peer->srcadr));
return;
}
/* Be conservative */
if (peer->flip == 0 && !L_ISEQU(&p_org, &peer->aorg)) {
peer->bogusorg++;
msyslog(LOG_INFO,
"receive: flip 0 KoD origin timestamp %#010x.%08x from %s does not match %#010x.%08x - ignoring.",
p_org.l_ui, p_org.l_uf,
ntoa(&peer->srcadr),
peer->aorg.l_ui, peer->aorg.l_uf);
return;
} else if (peer->flip == 1 && !L_ISEQU(&p_org, &peer->borg)) {
peer->bogusorg++;
msyslog(LOG_INFO,
"receive: flip 1 KoD origin timestamp %#010x.%08x from %s does not match interleave %#010x.%08x - ignoring.",
p_org.l_ui, p_org.l_uf,
ntoa(&peer->srcadr),
peer->borg.l_ui, peer->borg.l_uf);
return;
}
/*
* Basic mode checks:
*
* If there is no origin timestamp, it's either an initial packet
* or we've already received a response to our query. Of course,
* should 'aorg' be all-zero because this really was the original
* transmit timestamp, we'll ignore this reply. There is a window
* of one nanosecond once every 136 years' time where this is
* possible. We currently ignore this situation, as a completely
* zero timestamp is (quietly?) disallowed.
*
* Otherwise, check for bogus packet in basic mode.
* If it is bogus, switch to interleaved mode and resynchronize,
* but only after confirming the packet is not bogus in
* symmetric interleaved mode.
*
* This could also mean somebody is forging packets claiming to
* be from us, attempting to cause our server to KoD us.
*
* We have earlier asserted that hisstratum cannot be 0.
* If hisstratum is STRATUM_UNSPEC, it means he's not sync'd.
*/
/* XXX: FLAG_LOOPNONCE */
DEBUG_INSIST(0 == (FLAG_LOOPNONCE & peer->flags));
} else if (peer->flip == 0) {
if (0) {
} else if (L_ISZERO(&p_org)) {
const char *action;
#ifdef BUG3361
msyslog(LOG_INFO,
"receive: BUG 3361: Clearing peer->aorg ");
L_CLR(&peer->aorg);
/* Clear peer->nonce, too? */
#endif
/**/
switch (hismode) {
/* We allow 0org for: */
case UCHAR_MAX:
action = "Allow";
break;
/* We disallow 0org for: */
case MODE_UNSPEC:
case MODE_ACTIVE:
case MODE_PASSIVE:
case MODE_CLIENT:
case MODE_SERVER:
case MODE_BROADCAST:
action = "Drop";
peer->bogusorg++;
peer->flash |= TEST2; /* bogus */
break;
default:
action = ""; /* for cranky compilers / MSVC */
INSIST(!"receive(): impossible hismode");
break;
}
/**/
msyslog(LOG_INFO,
"receive: %s 0 origin timestamp from %s@%s xmt %#010x.%08x",
action, hm_str, ntoa(&peer->srcadr),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf));
} else if (!L_ISEQU(&p_org, &peer->aorg)) {
/* are there cases here where we should bail? */
/* Should we set TEST2 if we decide to try xleave? */
peer->bogusorg++;
peer->flash |= TEST2; /* bogus */
msyslog(LOG_INFO,
"receive: Unexpected origin timestamp %#010x.%08x does not match aorg %#010x.%08x from %s@%s xmt %#010x.%08x",
ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
peer->aorg.l_ui, peer->aorg.l_uf,
hm_str, ntoa(&peer->srcadr),
ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf));
if ( !L_ISZERO(&peer->dst)
&& L_ISEQU(&p_org, &peer->dst)) {
/* Might be the start of an interleave */
if (dynamic_interleave) {
peer->flip = 1;
report_event(PEVNT_XLEAVE, peer, NULL);
} else {
msyslog(LOG_INFO,
"receive: Dynamic interleave from %s@%s denied",
hm_str, ntoa(&peer->srcadr));
}
}
} else {
L_CLR(&peer->aorg);
/* XXX: FLAG_LOOPNONCE */
}
/*
* 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, duplicated or crossed. If
* found, flip and resynchronize.
*/
} else if ( !L_ISZERO(&peer->dst)
&& !L_ISEQU(&p_org, &peer->dst)) {
DPRINTF(2, ("receive: drop: Bogus packet in interleaved symmetric mode\n"));
peer->bogusorg++;
peer->flags |= FLAG_XBOGUS;
peer->flash |= TEST2; /* bogus */
#ifdef BUG3453
return; /* Bogus packet, we are done */
#endif
}
/**/
/*
* 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 (crypto_nak_test == VALIDNAK) {
report_event(PEVNT_AUTH, peer, "crypto_NAK");
peer->flash |= TEST5; /* bad auth */
peer->badauth++;
if (peer->flags & FLAG_PREEMPT) {
if (unpeer_crypto_nak_early) {
unpeer(peer);
}
DPRINTF(2, ("receive: drop: PREEMPT crypto_NAK\n"));
return;
}
#ifdef AUTOKEY
if (peer->crypto) {
peer_clear(peer, "AUTH");
}
#endif /* AUTOKEY */
DPRINTF(2, ("receive: drop: crypto_NAK\n"));
return;
/*
* If the digest fails or it's missing for authenticated
* associations, 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(peer->keyid || has_mac ||
(restrict_mask & RES_DONTTRUST), is_authentic)) {
if (peer->flash & PKT_TEST_MASK) {
msyslog(LOG_INFO,
"receive: Bad auth in packet with bad timestamps from %s denied - spoof?",
ntoa(&peer->srcadr));
return;
}
report_event(PEVNT_AUTH, peer, "digest");
peer->flash |= TEST5; /* bad auth */
peer->badauth++;
if ( has_mac
&& ( hismode == MODE_ACTIVE
|| hismode == MODE_PASSIVE))
fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask);
if (peer->flags & FLAG_PREEMPT) {
if (unpeer_digest_early) {
unpeer(peer);
}
}
#ifdef AUTOKEY
else if (peer_clear_digest_early && peer->crypto) {
peer_clear(peer, "AUTH");
}
#endif /* AUTOKEY */
DPRINTF(2, ("receive: drop: Bad or missing AUTH\n"));
return;
}
/*
* For broadcast packets:
*
* HMS: This next line never made much sense to me, even
* when it was up higher:
* If an initial volley, bail out now and let the
* client do its stuff.
*
* If the packet has not failed authentication, then
* - if the origin timestamp is nonzero this is an
* interleaved broadcast, so restart the protocol.
* - else, this is not an interleaved broadcast packet.
*/
if (hismode == MODE_BROADCAST) {
if ( is_authentic == AUTH_OK
|| is_authentic == AUTH_NONE) {
if (!L_ISZERO(&p_org)) {
if (!(peer->flags & FLAG_XB)) {
msyslog(LOG_INFO,
"receive: Broadcast server at %s is in interleave mode",
ntoa(&peer->srcadr));
peer->flags |= FLAG_XB;
peer->aorg = p_xmt;
peer->borg = rbufp->recv_time;
report_event(PEVNT_XLEAVE, peer, NULL);
return;
}
} else if (peer->flags & FLAG_XB) {
msyslog(LOG_INFO,
"receive: Broadcast server at %s is no longer in interleave mode",
ntoa(&peer->srcadr));
peer->flags &= ~FLAG_XB;
}
} else {
msyslog(LOG_INFO,
"receive: Bad broadcast auth (%d) from %s",
is_authentic, ntoa(&peer->srcadr));
}
/*
* Now that we know the packet is correctly authenticated,
* update peer->bxmt.
*/
peer->bxmt = p_xmt;
}
/*
** 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;
/*
* 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 maximum and advance the headway to give the sender some
* headroom. Very intricate.
*/
/*
* Check for any kiss codes. Note this is only used when a server
* responds to a packet request.
*/
/*
* Check to see if this is a RATE Kiss Code
* Currently this kiss code will accept whatever poll
* rate that the server sends
*/
peer->ppoll = max(peer->minpoll, pkt->ppoll);
if (kissCode == RATEKISS) {
peer->selbroken++; /* Increment the KoD count */
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, 0);
return; /* kiss-o'-death */
}
if (kissCode != NOKISS) {
peer->selbroken++; /* Increment the KoD count */
return; /* Drop any other kiss code packets */
}
/*
* XXX
*/
/*
* If:
* - this is a *cast (uni-, broad-, or m-) server packet
* - and it's symmetric-key authenticated
* then see if the sender's IP is trusted for this keyid.
* If it is, great - nothing special to do here.
* Otherwise, we should report and bail.
*
* Autokey-authenticated packets are accepted.
*/
switch (hismode) {
case MODE_SERVER: /* server mode */
case MODE_BROADCAST: /* broadcast mode */
case MODE_ACTIVE: /* symmetric active mode */
case MODE_PASSIVE: /* symmetric passive mode */
if ( is_authentic == AUTH_OK
&& skeyid
&& skeyid <= NTP_MAXKEY
&& !authistrustedip(skeyid, &peer->srcadr)) {
report_event(PEVNT_AUTH, peer, "authIP");
peer->badauth++;
return;
}
break;
case MODE_CLIENT: /* client mode */
#if 0 /* At this point, MODE_CONTROL is overloaded by MODE_BCLIENT */
case MODE_CONTROL: /* control mode */
#endif
case MODE_PRIVATE: /* private mode */
case MODE_BCLIENT: /* broadcast client mode */
break;
case MODE_UNSPEC: /* unspecified (old version) */
default:
msyslog(LOG_INFO,
"receive: Unexpected mode (%d) in packet from %s",
hismode, ntoa(&peer->srcadr));
break;
}
/*
* That was hard and I am sweaty, but the packet is squeaky
* clean. Get on with real work.
*/
peer->timereceived = current_time;
peer->timelastrec = current_time;
if (is_authentic == AUTH_OK)
peer->flags |= FLAG_AUTHENTIC;
else
peer->flags &= ~FLAG_AUTHENTIC;
#ifdef AUTOKEY
/*
* 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 autokey 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) {
if (unpeer_crypto_early) {
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
* refresh certificates and leapseconds values.
*/
if (current_time > peer->refresh) {
report_event(PEVNT_RESTART, peer,
"crypto refresh");
peer_clear(peer, "TIME");
return;
}
}
#endif /* AUTOKEY */
/*
* 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. Leave if the packet is not good.
*/
process_packet(peer, pkt, rbufp->recv_length);
if (peer->flash & PKT_TEST_MASK)
return;
/* [bug 3592] Update poll. Ideally this should not happen in a
* receive branch, but too much is going on here... at least we
* do it only if the packet was good!
*/
poll_update(peer, peer->hpoll, (peer->hmode == MODE_CLIENT));
/*
* 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 < (1U << min(peer->ppoll,
peer->hpoll)) / 2)
peer->nextdate++;
else
peer->nextdate--;
}
}
/*
* process_packet - Packet Procedure, a la Section 3.4.4 of RFC-1305
* 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, pversion, pstratum;
char statstr[NTP_MAXSTRLEN];
#ifdef ASSYM
int itemp;
double etemp, ftemp, td;
#endif /* ASSYM */
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);
pversion = PKT_VERSION(pkt->li_vn_mode);
pstratum = PKT_TO_STRATUM(pkt->stratum);
/*
* 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++;
DPRINTF(1, ("packet: flash header %04x\n",
peer->flash));
/* [Bug 3592] do *not* update poll on bad packets! */
return;
}
/*
* update stats, now that we really handle this packet:
*/
sys_processed++;
peer->processed++;
/*
* 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,
pleap, pversion, pmode, pstratum, pkt->ppoll, pkt->precision,
p_del, p_disp, pkt->refid,
len - MIN_V4_PKT_LEN, (u_char *)&pkt->exten);
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;
}
/*
* 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.) {
snprintf(statstr, sizeof(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.) {
/* drop all if in the initial volley */
if (FLAG_BC_VOL & peer->flags)
goto bcc_init_volley_fail;
snprintf(statstr, sizeof(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.
* [Bug 3031] Don't keep this peer when the delay
* calculation gives reason to suspect clock steps.
* This is assumed for delays > 50ms.
*/
if (FLAG_BC_VOL & peer->flags) {
peer->flags &= ~FLAG_BC_VOL;
peer->delay = fabs(peer->offset - p_offset) * 2;
DPRINTF(2, ("broadcast volley: initial delay=%.6f\n",
peer->delay));
if (peer->delay > fabs(sys_bdelay)) {
bcc_init_volley_fail:
DPRINTF(2, ("%s", "broadcast volley: initial delay exceeds limit\n"));
unpeer(peer);
return;
}
}
peer->nextdate = current_time + (1u << peer->ppoll) - 2u;
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_del = max(p_del, LOGTOD(sys_precision));
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;
DPRINTF(2, ("packet: t21 %.9lf %d t34 %.9lf %d\n", peer->t21,
peer->t21_bytes, peer->t34, peer->t34_bytes));
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;
DPRINTF(2, ("packet: del %.6lf r21 %.1lf r34 %.1lf %.6lf\n",
p_del, peer->r21 / 1e3, peer->r34 / 1e3,
td));
}
#endif /* ASSYM */
/*
* That was awesome. Now hand off to the clock filter.
*/
clock_filter(peer, p_offset + peer->bias, 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 AUTOKEY
if (peer->flags & FLAG_SKEY) {
if (!(~peer->crypto & CRYPTO_FLAG_ALL))
peer->hmode = MODE_BCLIENT;
} else {
peer->hmode = MODE_BCLIENT;
}
#else /* !AUTOKEY follows */
peer->hmode = MODE_BCLIENT;
#endif /* !AUTOKEY */
}
}
/*
* 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, 0);
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);
/*
* Root Dispersion (E) is defined (in RFC 5905) as:
*
* E = p.epsilon_r + p.epsilon + p.psi + PHI*(s.t - p.t) + |THETA|
*
* where:
* p.epsilon_r is the PollProc's root dispersion
* p.epsilon is the PollProc's dispersion
* p.psi is the PollProc's jitter
* THETA is the combined offset
*
* NB: Think Hard about where these numbers come from and
* what they mean. When did peer->update happen? Has anything
* interesting happened since then? What values are the most
* defensible? Why?
*
* DLM thinks this equation is probably the best of all worse choices.
*/
dtemp = peer->rootdisp
+ peer->disp
+ sys_jitter
+ clock_phi * (current_time - peer->update)
+ fabs(sys_offset);
p2_rootdisp = prev_rootdisp;
prev_rootdisp = sys_rootdisp;
if (dtemp > sys_mindisp)
sys_rootdisp = dtemp;
else
sys_rootdisp = sys_mindisp;
sys_rootdelay = peer->delay + peer->rootdelay;
p2_reftime = prev_reftime;
p2_time = prev_time;
prev_reftime = sys_reftime;
prev_time = current_time + 64 + (rand() & 0x3f); /* 64-127 s */
sys_reftime = peer->dst;
DPRINTF(1, ("clock_update: at %lu sample %lu associd %d\n",
current_time, peer->epoch, peer->associd));
/*
* 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();
set_sys_leap(LEAP_NOTINSYNC);
sys_stratum = STRATUM_UNSPEC;
memcpy(&sys_refid, "STEP", 4);
sys_rootdelay = 0;
p2_rootdisp = 0;
prev_rootdisp = 0;
sys_rootdisp = 0;
L_CLR(&p2_reftime); /* Should we clear p2_reftime? */
L_CLR(&prev_reftime); /* Should we clear prev_reftime? */
L_CLR(&sys_reftime);
sys_jitter = LOGTOD(sys_precision);
leapsec_reset_frame();
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) {
set_sys_leap(LEAP_NOWARNING);
#ifdef AUTOKEY
if (crypto_flags)
crypto_update();
#endif /* AUTOKEY */
/*
* If our parent process is waiting for the
* first clock sync, send them home satisfied.
*/
#ifdef HAVE_WORKING_FORK
if (daemon_pipe[1] != -1) {
write(daemon_pipe[1], "S\n", 2);
close(daemon_pipe[1]);
daemon_pipe[1] = -1;
DPRINTF(1, ("notified parent --wait-sync is done\n"));
}
#endif /* HAVE_WORKING_FORK */
}
/*
* If there is no leap second pending and the number of
* survivor leap bits is greater than half the number of
* survivors, try to schedule a leap for the end of the
* current month. (This only works if no leap second for
* that range is in the table, so doing this more than
* once is mostly harmless.)
*/
if (leapsec == LSPROX_NOWARN) {
if ( leap_vote_ins > leap_vote_del
&& leap_vote_ins > sys_survivors / 2) {
get_systime(&now);
leapsec_add_dyn(TRUE, now.l_ui, NULL);
}
if ( leap_vote_del > leap_vote_ins
&& leap_vote_del > sys_survivors / 2) {
get_systime(&now);
leapsec_add_dyn(FALSE, now.l_ui, NULL);
}
}
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 */
u_char mpoll,
u_char skewpoll
)
{
u_long next, utemp, limit;
u_char hpoll;
/*
* 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.
*
* Clamp the poll interval between minpoll and maxpoll.
*/
hpoll = max(min(peer->maxpoll, mpoll), peer->minpoll);
#ifdef AUTOKEY
/*
* 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 /* AUTOKEY */
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 pending 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.
*/
utemp = current_time + max(peer->throttle - (NTP_SHIFT - 1) *
(1 << peer->minpoll), ntp_minpkt);
/*[Bug 3592] avoid unlimited postpone of next poll */
limit = (2u << hpoll);
if (limit > 64)
limit -= (limit >> 2);
limit += peer->outdate;
if (limit < current_time)
limit = current_time;
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 AUTOKEY
/*
* 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 + ntp_minpkt != utemp)
peer->nextdate = utemp;
} else {
peer->nextdate = utemp;
}
#endif /* AUTOKEY */
/*
* 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
hpoll = min(peer->ppoll, peer->hpoll);
#ifdef REFCLOCK
if (peer->flags & FLAG_REFCLOCK)
next = 1 << hpoll;
else
#endif /* REFCLOCK */
next = ((0x1000UL | (ntp_random() & 0x0ff)) <<
hpoll) >> 12;
next += peer->outdate;
/* XXX: bug3596: Deal with poll skew list? */
if (skewpoll) {
psl_item psi;
if (0 == get_pollskew(hpoll, &psi)) {
int sub = psi.sub;
int qty = psi.qty;
int msk = psi.msk;
int val;
if ( 0 != sub
|| 0 != qty) {
do {
val = ntp_random() & msk;
} while (val > qty);
next -= sub;
next += val;
}
} else {
/* get_pollskew() already logged this */
}
}
if (next > utemp)
peer->nextdate = next;
else
peer->nextdate = utemp;
if (peer->throttle > (1 << peer->minpoll))
peer->nextdate += ntp_minpkt;
}
/*[Bug 3592] avoid unlimited postpone of next poll */
if (peer->nextdate > limit) {
DPRINTF(1, ("poll_update: clamp reached; limit %lu next %lu\n",
limit, peer->nextdate));
peer->nextdate = limit;
}
DPRINTF(2, ("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));
}
/*
* peer_clear - clear peer filter registers. See Section 3.4.8 of the
* spec.
*/
void
peer_clear(
struct peer *peer, /* peer structure */
const char *ident /* tally lights */
)
{
u_char u;
l_fp bxmt = peer->bxmt; /* bcast clients retain this! */
#ifdef AUTOKEY
/*
* 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 /* AUTOKEY */
/*
* Clear all values, including the optional crypto values above.
*/
memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO(peer));
peer->ppoll = peer->maxpoll;
peer->hpoll = peer->minpoll;
peer->disp = MAXDISPERSE;
peer->flash = peer_unfit(peer);
peer->jitter = LOGTOD(sys_precision);
/* Don't throw away our broadcast replay protection */
if (peer->hmode == MODE_BCLIENT)
peer->bxmt = bxmt;
/*
* If interleave mode, initialize the alternate origin switch.
*/
if (peer->flags & FLAG_XLEAVE)
peer->flip = 1;
for (u = 0; u < NTP_SHIFT; u++) {
peer->filter_order[u] = u;
peer->filter_disp[u] = MAXDISPERSE;
}
#ifdef REFCLOCK
if (!(peer->flags & FLAG_REFCLOCK)) {
#endif
peer->leap = LEAP_NOTINSYNC;
peer->stratum = STRATUM_UNSPEC;
memcpy(&peer->refid, ident, 4);
#ifdef REFCLOCK
} else {
/* Clear refclock sample filter */
peer->procptr->codeproc = 0;
peer->procptr->coderecv = 0;
}
#endif
/*
* During initialization use the association count to spread out
* the polls at one-second intervals. Passive associations'
* first poll is delayed by the "discard minimum" to avoid rate
* limiting. Other post-startup new or cleared associations
* randomize the first poll over the minimum poll interval to
* avoid implosion.
*/
peer->nextdate = peer->update = peer->outdate = current_time;
if (initializing) {
peer->nextdate += peer_associations;
} else if (MODE_PASSIVE == peer->hmode) {
peer->nextdate += ntp_minpkt;
} else {
peer->nextdate += ntp_random() % peer->minpoll;
}
#ifdef AUTOKEY
peer->refresh = current_time + (1 << NTP_REFRESH);
#endif /* AUTOKEY */
DPRINTF(1, ("peer_clear: at %ld next %ld associd %d refid %s\n",
current_time, peer->nextdate, peer->associd,
ident));
}
/*
* 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] >
(u_long)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 has stabilized, sort the samples by distance.
*/
if (freq_cnt == 0) {
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) {
DPRINTF(2, ("clock_filter: old sample %lu\n", current_time -
peer->filter_epoch[k]));
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);
DPRINTF(1, ("clock_filter: n %d off %.6f del %.6f dsp %.6f jit %.6f\n",
m, peer->offset, peer->delay, peer->disp,
peer->jitter));
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, nl2;
int allow;
int speer;
double d, e, f, g;
double high, low;
double speermet;
double lastresort_dist = MAXDISPERSE;
double orphmet = 2.0 * U_INT32_MAX; /* 2x is greater than */
struct endpoint endp;
struct peer *osys_peer;
struct peer *sys_prefer = NULL; /* prefer peer */
struct peer *typesystem = NULL;
struct peer *typelastresort = NULL;
struct peer *typeorphan = NULL;
#ifdef REFCLOCK
struct peer *typeacts = NULL;
struct peer *typelocal = NULL;
struct peer *typepps = NULL;
#endif /* REFCLOCK */
static struct endpoint *endpoint = NULL;
static int *indx = NULL;
static peer_select *peers = NULL;
static u_int endpoint_size = 0;
static u_int peers_size = 0;
static u_int indx_size = 0;
size_t octets;
/*
* Initialize and create endpoint, index and peer lists big
* enough to handle all associations.
*/
osys_peer = sys_peer;
sys_survivors = 0;
#ifdef LOCKCLOCK
set_sys_leap(LEAP_NOTINSYNC);
sys_stratum = STRATUM_UNSPEC;
memcpy(&sys_refid, "DOWN", 4);
#endif /* LOCKCLOCK */
/*
* Allocate dynamic space depending on the number of
* associations.
*/
nlist = 1;
for (peer = peer_list; peer != NULL; peer = peer->p_link)
nlist++;
endpoint_size = ALIGNED_SIZE(nlist * 2 * sizeof(*endpoint));
peers_size = ALIGNED_SIZE(nlist * sizeof(*peers));
indx_size = ALIGNED_SIZE(nlist * 2 * sizeof(*indx));
octets = endpoint_size + peers_size + indx_size;
endpoint = erealloc(endpoint, octets);
peers = INC_ALIGNED_PTR(endpoint, endpoint_size);
indx = INC_ALIGNED_PTR(peers, peers_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 = nl2 = 0; /* none yet */
for (peer = peer_list; peer != NULL; peer = peer->p_link) {
peer->new_status = CTL_PST_SEL_REJECT;
/*
* Leave the island immediately if the peer is
* unfit to synchronize.
*/
if (peer_unfit(peer)) {
continue;
}
/*
* If we have never been synchronised, look for any peer
* which has ever been synchronised and pick the one which
* has the lowest root distance. This can be used as a last
* resort if all else fails. Once we get an initial sync
* with this peer, sys_reftime gets set and so this
* function becomes disabled.
*/
if (L_ISZERO(&sys_reftime)) {
d = root_distance(peer);
if (!L_ISZERO(&peer->reftime) && d < lastresort_dist) {
typelastresort = peer;
lastresort_dist = d;
}
}
/*
* 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 ( current_time > orphwait
&& typelocal == NULL)
typelocal = peer;
continue;
case REFCLK_ACTS:
if ( current_time > orphwait
&& 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;
f = root_distance(peer);
peers[nlist].peer = peer;
peers[nlist].error = peer->jitter;
peers[nlist].synch = f;
nlist++;
/*
* Insert each interval endpoint on the unsorted
* endpoint[] list.
*/
e = peer->offset;
endpoint[nl2].type = -1; /* lower end */
endpoint[nl2].val = e - f;
nl2++;
endpoint[nl2].type = 1; /* upper end */
endpoint[nl2].val = e + f;
nl2++;
}
/*
* Construct sorted indx[] of endpoint[] indexes ordered by
* offset.
*/
for (i = 0; i < nl2; i++)
indx[i] = i;
for (i = 0; i < nl2; i++) {
endp = endpoint[indx[i]];
e = endp.val;
k = i;
for (j = i + 1; j < nl2; j++) {
endp = endpoint[indx[j]];
if (endp.val < e) {
e = endp.val;
k = j;
}
}
if (k != i) {
j = indx[k];
indx[k] = indx[i];
indx[i] = j;
}
}
for (i = 0; i < nl2; i++)
DPRINTF(3, ("select: endpoint %2d %.6f\n",
endpoint[indx[i]].type, endpoint[indx[i]].val));
/*
* 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++) {
/*
* Bound the interval (low, high) as the smallest
* interval containing points from the most sources.
*/
n = 0;
for (i = 0; i < nl2; i++) {
low = endpoint[indx[i]].val;
n -= endpoint[indx[i]].type;
if (n >= nlist - allow)
break;
}
n = 0;
for (j = nl2 - 1; j >= 0; j--) {
high = endpoint[indx[j]].val;
n += endpoint[indx[j]].type;
if (n >= nlist - allow)
break;
}
/*
* 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. Whittle candidate list of 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.
*
* We assert the correct time is contained in the interval, but
* the best offset estimate for the interval might not be
* contained in the interval. For this purpose, a truechimer is
* defined as the midpoint of an interval that overlaps the
* intersection interval.
*/
j = 0;
for (i = 0; i < nlist; i++) {
double h;
peer = peers[i].peer;
h = peers[i].synch;
if (( high <= low
|| peer->offset + h < low
|| peer->offset - h > 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;
if (!(peer->flags & FLAG_TSTAMP_PPS))
continue;
}
#endif /* REFCLOCK */
if (j != i)
peers[j] = peers[i];
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) {
peers[0].error = 0;
peers[0].synch = sys_mindisp;
#ifdef REFCLOCK
if (typeacts != NULL) {
peers[0].peer = typeacts;
nlist = 1;
} else if (typelocal != NULL) {
peers[0].peer = typelocal;
nlist = 1;
} else
#endif /* REFCLOCK */
if (typeorphan != NULL) {
peers[0].peer = typeorphan;
nlist = 1;
} else if (typelastresort != NULL) {
peers[0].peer = typelastresort;
nlist = 1;
}
}
/*
* Mark the candidates at this point as truechimers.
*/
for (i = 0; i < nlist; i++) {
peers[i].peer->new_status = CTL_PST_SEL_SELCAND;
DPRINTF(2, ("select: survivor %s %f\n",
stoa(&peers[i].peer->srcadr), peers[i].synch));
}
/*
* Now, vote outliers off the island by select jitter weighted
* by root distance. Continue voting as long as there are more
* than sys_minclock survivors and the select jitter of the peer
* with the worst metric is greater than the minimum peer
* jitter. Stop if we are about to discard a TRUE or PREFER
* peer, who of course have the immunity idol.
*/
while (1) {
d = 1e9;
e = -1e9;
g = 0;
k = 0;
for (i = 0; i < nlist; i++) {
if (peers[i].error < d)
d = peers[i].error;
peers[i].seljit = 0;
if (nlist > 1) {
f = 0;
for (j = 0; j < nlist; j++)
f += DIFF(peers[j].peer->offset,
peers[i].peer->offset);
peers[i].seljit = SQRT(f / (nlist - 1));
}
if (peers[i].seljit * peers[i].synch > e) {
g = peers[i].seljit;
e = peers[i].seljit * peers[i].synch;
k = i;
}
}
g = max(g, LOGTOD(sys_precision));
if ( nlist <= max(1, sys_minclock)
|| g <= d
|| ((FLAG_TRUE | FLAG_PREFER) & peers[k].peer->flags))
break;
DPRINTF(3, ("select: drop %s seljit %.6f jit %.6f\n",
ntoa(&peers[k].peer->srcadr), g, d));
if (nlist > sys_maxclock)
peers[k].peer->new_status = CTL_PST_SEL_EXCESS;
for (j = k + 1; j < nlist; j++)
peers[j - 1] = peers[j];
nlist--;
}
/*
* What remains is a list usually not greater than sys_minclock
* peers. Note that unsynchronized peers cannot survive this
* far. Count and mark these survivors.
*
* 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.
*
* Choose the system peer using a hybrid metric composed of the
* selection jitter scaled by the root distance augmented by
* stratum scaled by sys_mindisp (.001 by default). The goal of
* the small stratum factor is to avoid clockhop between a
* reference clock and a network peer which has a refclock and
* is using an older ntpd, which does not floor sys_rootdisp at
* sys_mindisp.
*
* In contrast, ntpd 4.2.6 and earlier used stratum primarily
* in selecting the system peer, using a weight of 1 second of
* additional root distance per stratum. This heavy bias is no
* longer appropriate, as the scaled root distance provides a
* more rational metric carrying the cumulative error budget.
*/
e = 1e9;
speer = 0;
leap_vote_ins = 0;
leap_vote_del = 0;
for (i = 0; i < nlist; i++) {
peer = peers[i].peer;
peer->unreach = 0;
peer->new_status = CTL_PST_SEL_SYNCCAND;
sys_survivors++;
if (peer->leap == LEAP_ADDSECOND) {
if (peer->flags & FLAG_REFCLOCK)
leap_vote_ins = nlist;
else if (leap_vote_ins < nlist)
leap_vote_ins++;
}
if (peer->leap == LEAP_DELSECOND) {
if (peer->flags & FLAG_REFCLOCK)
leap_vote_del = nlist;
else if (leap_vote_del < nlist)
leap_vote_del++;
}
if (peer->flags & FLAG_PREFER)
sys_prefer = peer;
speermet = peers[i].seljit * peers[i].synch +
peer->stratum * sys_mindisp;
if (speermet < e) {
e = speermet;
speer = i;
}
}
/*
* Unless there are at least sys_misane survivors, leave the
* building dark. Otherwise, do a clockhop dance. Ordinarily,
* use the selected survivor speer. However, if the current
* system peer is not speer, stay with the current system peer
* as long as it doesn't get too old or too ugly.
*/
if (nlist > 0 && nlist >= sys_minsane) {
double x;
typesystem = peers[speer].peer;
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;
DPRINTF(1, ("select: clockhop %d %.6f %.6f\n",
j, x, sys_clockhop));
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(peers, sys_survivors, speer);
} else {
typesystem = sys_prefer;
sys_clockhop = 0;
typesystem->new_status = CTL_PST_SEL_SYSPEER;
sys_offset = typesystem->offset;
sys_jitter = typesystem->jitter;
}
DPRINTF(1, ("select: combine offset %.9f jitter %.9f\n",
sys_offset, sys_jitter));
}
#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;
DPRINTF(1, ("select: pps offset %.9f jitter %.9f\n",
sys_offset, sys_jitter));
}
#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) {
orphwait = current_time + sys_orphwait;
report_event(EVNT_NOPEER, NULL, NULL);
}
sys_peer = NULL;
for (peer = peer_list; peer != NULL; peer = peer->p_link)
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 (peer = peer_list; peer != NULL; peer = peer->p_link)
peer->status = peer->new_status;
clock_update(typesystem);
}
static void
clock_combine(
peer_select * peers, /* survivor list */
int npeers, /* number of survivors */
int syspeer /* index of sys.peer */
)
{
int i;
double x, y, z, w;
y = z = w = 0;
for (i = 0; i < npeers; i++) {
x = 1. / peers[i].synch;
y += x;
z += x * peers[i].peer->offset;
w += x * DIFF(peers[i].peer->offset,
peers[syspeer].peer->offset);
}
sys_offset = z / y;
sys_jitter = SQRT(w / y + SQUARE(peers[syspeer].seljit));
}
/*
* root_distance - compute synchronization distance from peer to root
*/
static double
root_distance(
struct peer *peer /* peer structure pointer */
)
{
double dtemp;
/*
* Root Distance (LAMBDA) is defined as:
* (delta + DELTA)/2 + epsilon + EPSILON + D
*
* where:
* delta is the round-trip delay
* DELTA is the root delay
* epsilon is the peer dispersion
* + (15 usec each second)
* EPSILON is the root dispersion
* D is sys_jitter
*
* NB: Think hard about why we are using these values, and what
* the alternatives are, and the various pros/cons.
*
* DLM thinks these are probably the best choices from any of the
* other worse choices.
*/
dtemp = (peer->delay + peer->rootdelay) / 2
+ peer->disp
+ clock_phi * (current_time - peer->update)
+ peer->rootdisp
+ peer->jitter;
/*
* 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.
*/
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 */
size_t 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));
/* Use sys_reftime for peer exchanges */
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;
if (
#ifdef AUTOKEY
!(peer->flags & FLAG_SKEY) &&
#endif /* !AUTOKEY */
peer->keyid == 0) {
/*
* 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 >= sys_ttlmax) ? sys_ttlmax : 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);
DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d len %zu xmt %#010x.%08x\n",
current_time,
peer->dstadr ? stoa(&peer->dstadr->sin) : "-",
stoa(&peer->srcadr), peer->hmode, sendlen,
xmt_tx.l_ui, xmt_tx.l_uf));
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 AUTOKEY
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, hostval.ptr);
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, hostval.ptr);
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, hostval.ptr);
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, hostval.ptr);
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 > (int)LEN_PKT_NOMAC) {
session_key(&peer->dstadr->sin, &peer->srcadr,
xkeyid, 0, 2);
}
}
#endif /* AUTOKEY */
/*
* 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 AUTOKEY
if (xkeyid > NTP_MAXKEY)
authtrust(xkeyid, 0);
#endif /* AUTOKEY */
if (sendlen > sizeof(xpkt)) {
msyslog(LOG_ERR, "peer_xmit: buffer overflow %zu", sendlen);
exit (-1);
}
peer->t21_bytes = sendlen;
sendpkt(&peer->srcadr, peer->dstadr,
sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : 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 AUTOKEY
DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu index %d\n",
current_time, latoa(peer->dstadr),
ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen,
peer->keynumber));
#else /* !AUTOKEY follows */
DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu\n",
current_time, peer->dstadr ?
ntoa(&peer->dstadr->sin) : "-",
ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen));
#endif /* !AUTOKEY */
return;
}
#ifdef LEAP_SMEAR
static void
leap_smear_add_offs(
l_fp *t,
l_fp *t_recv
)
{
L_ADD(t, &leap_smear.offset);
/*
** XXX: Should the smear be added to the root dispersion?
*/
return;
}
#endif /* LEAP_SMEAR */
/*
* 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 */ /* XXX: HMS: really? */
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;
size_t sendlen;
#ifdef AUTOKEY
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);
xpkt.precision = rpkt->precision;
memcpy(&xpkt.refid, "RATE", 4);
xpkt.rootdelay = rpkt->rootdelay;
xpkt.rootdisp = rpkt->rootdisp;
xpkt.reftime = rpkt->reftime;
xpkt.org = rpkt->xmt;
xpkt.rec = rpkt->xmt;
xpkt.xmt = rpkt->xmt;
/*
* This is a normal packet. Use the system variables.
*/
} else {
double this_rootdisp;
l_fp this_ref_time;
#ifdef LEAP_SMEAR
/*
* Make copies of the variables which can be affected by smearing.
*/
l_fp this_recv_time;
#endif
/*
* If we are inside the leap smear interval we add
* the current smear offset to:
* - the packet receive time,
* - the packet transmit time,
* - and eventually to the reftime to make sure the
* reftime isn't later than the transmit/receive times.
*/
xpkt.li_vn_mode = PKT_LI_VN_MODE(xmt_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));
/*
** Server Response Fuzzing
**
** Which values do we want to use for reftime and rootdisp?
*/
if ( MODE_SERVER == xmode
&& RES_SRVRSPFUZ & flags) {
if (current_time < p2_time) {
this_ref_time = p2_reftime;
this_rootdisp = p2_rootdisp;
} else if (current_time < prev_time) {
this_ref_time = prev_reftime;
this_rootdisp = prev_rootdisp;
} else {
this_ref_time = sys_reftime;
this_rootdisp = sys_rootdisp;
}
SRVRSP_FUZZ(this_ref_time);
} else {
this_ref_time = sys_reftime;
this_rootdisp = sys_rootdisp;
}
/*
** ROOT DISPERSION
*/
xpkt.rootdisp = HTONS_FP(DTOUFP(this_rootdisp));
/*
** REFTIME
*/
#ifdef LEAP_SMEAR
if (leap_smear.in_progress) {
/* adjust the reftime by the same amount as the
* leap smear, as we don't want to risk the
* reftime being later than the transmit time.
*/
leap_smear_add_offs(&this_ref_time, NULL);
}
#endif
HTONL_FP(&this_ref_time, &xpkt.reftime);
/*
** REFID
*/
#ifdef LEAP_SMEAR
if (leap_smear.in_progress) {
xpkt.refid = convertLFPToRefID(leap_smear.offset);
DPRINTF(2, ("fast_xmit: leap_smear.in_progress: refid %8x, smear %s\n",
ntohl(xpkt.refid),
lfptoa(&leap_smear.offset, 8)
));
}
#endif
/*
** ORIGIN
*/
xpkt.org = rpkt->xmt;
/*
** RECEIVE
*/
#ifdef LEAP_SMEAR
this_recv_time = rbufp->recv_time;
if (leap_smear.in_progress)
leap_smear_add_offs(&this_recv_time, NULL);
HTONL_FP(&this_recv_time, &xpkt.rec);
#else
HTONL_FP(&rbufp->recv_time, &xpkt.rec);
#endif
/*
** TRANSMIT
*/
get_systime(&xmt_tx);
#ifdef LEAP_SMEAR
if (leap_smear.in_progress)
leap_smear_add_offs(&xmt_tx, &this_recv_time);
#endif
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);
DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d len %lu\n",
current_time, stoa(&rbufp->dstadr->sin),
stoa(&rbufp->recv_srcadr), xmode,
(u_long)sendlen));
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 AUTOKEY
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 ((size_t)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 /* AUTOKEY */
get_systime(&xmt_tx);
sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
#ifdef AUTOKEY
if (xkeyid > NTP_MAXKEY)
authtrust(xkeyid, 0);
#endif /* AUTOKEY */
sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen);
get_systime(&xmt_ty);
L_SUB(&xmt_ty, &xmt_tx);
sys_authdelay = xmt_ty;
DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d keyid %08x len %lu\n",
current_time, ntoa(&rbufp->dstadr->sin),
ntoa(&rbufp->recv_srcadr), xmode, xkeyid,
(u_long)sendlen));
}
/*
* pool_xmit - resolve hostname or send unicast solicitation for pool.
*/
static void
pool_xmit(
struct peer *pool /* pool solicitor association */
)
{
#ifdef WORKER
struct pkt xpkt; /* transmit packet structure */
struct addrinfo hints;
int rc;
struct interface * lcladr;
sockaddr_u * rmtadr;
r4addr r4a;
u_short restrict_mask;
struct peer * p;
l_fp xmt_tx;
DEBUG_REQUIRE(pool);
if (NULL == pool->ai) {
if (pool->addrs != NULL) {
/* free() is used with copy_addrinfo_list() */
free(pool->addrs);
pool->addrs = NULL;
}
ZERO(hints);
hints.ai_family = AF(&pool->srcadr);
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
/* ignore getaddrinfo_sometime() errors, we will retry */
rc = getaddrinfo_sometime(
pool->hostname,
"ntp",
&hints,
0, /* no retry */
&pool_name_resolved,
(void *)(intptr_t)pool->associd);
if (!rc)
DPRINTF(1, ("pool DNS lookup %s started\n",
pool->hostname));
else
msyslog(LOG_ERR,
"unable to start pool DNS %s: %m",
pool->hostname);
return;
}
do {
/* copy_addrinfo_list ai_addr points to a sockaddr_u */
rmtadr = (sockaddr_u *)(void *)pool->ai->ai_addr;
pool->ai = pool->ai->ai_next;
p = findexistingpeer(rmtadr, NULL, NULL, MODE_CLIENT, 0, NULL);
} while (p != NULL && pool->ai != NULL);
if (p != NULL)
return; /* out of addresses, re-query DNS next poll */
restrictions(rmtadr, &r4a);
restrict_mask = r4a.rflags;
if (RES_FLAGS & restrict_mask)
restrict_source(rmtadr, 0,
current_time + POOL_SOLICIT_WINDOW + 1);
lcladr = findinterface(rmtadr);
memset(&xpkt, 0, sizeof(xpkt));
xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, pool->version,
MODE_CLIENT);
xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
xpkt.ppoll = pool->hpoll;
xpkt.precision = sys_precision;
xpkt.refid = sys_refid;
xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp));
/* Bug 3596: What are the pros/cons of using sys_reftime here? */
HTONL_FP(&sys_reftime, &xpkt.reftime);
/* HMS: the following is better done after the ntp_random() calls */
get_systime(&xmt_tx);
pool->aorg = xmt_tx;
if (FLAG_LOOPNONCE & pool->flags) {
l_fp nonce;
do {
nonce.l_ui = ntp_random();
} while (0 == nonce.l_ui);
do {
nonce.l_uf = ntp_random();
} while (0 == nonce.l_uf);
pool->nonce = nonce;
HTONL_FP(&nonce, &xpkt.xmt);
} else {
L_CLR(&pool->nonce);
HTONL_FP(&xmt_tx, &xpkt.xmt);
}
sendpkt(rmtadr, lcladr,
sys_ttl[(pool->ttl >= sys_ttlmax) ? sys_ttlmax : pool->ttl],
&xpkt, LEN_PKT_NOMAC);
pool->sent++;
pool->throttle += (1 << pool->minpoll) - 2;
DPRINTF(1, ("pool_xmit: at %ld %s->%s pool\n",
current_time, latoa(lcladr), stoa(rmtadr)));
msyslog(LOG_INFO, "Soliciting pool server %s", stoa(rmtadr));
#endif /* WORKER */
}
#ifdef AUTOKEY
/*
* group_test - test if this is the same group
*
* host assoc return action
* none none 0 mobilize *
* none group 0 mobilize *
* group none 0 mobilize *
* group group 1 mobilize
* group different 1 ignore
* * ignore if notrust
*/
int
group_test(
char *grp,
char *ident
)
{
if (grp == NULL)
return (0);
if (strcmp(grp, sys_groupname) == 0)
return (0);
if (ident == NULL)
return (1);
if (strcmp(grp, ident) == 0)
return (0);
return (1);
}
#endif /* AUTOKEY */
#ifdef WORKER
void
pool_name_resolved(
int rescode,
int gai_errno,
void * context,
const char * name,
const char * service,
const struct addrinfo * hints,
const struct addrinfo * res
)
{
struct peer * pool; /* pool solicitor association */
associd_t assoc;
if (rescode) {
msyslog(LOG_ERR,
"error resolving pool %s: %s (%d)",
name, gai_strerror(rescode), rescode);
return;
}
assoc = (associd_t)(intptr_t)context;
pool = findpeerbyassoc(assoc);
if (NULL == pool) {
msyslog(LOG_ERR,
"Could not find assoc %u for pool DNS %s",
assoc, name);
return;
}
DPRINTF(1, ("pool DNS %s completed\n", name));
pool->addrs = copy_addrinfo_list(res);
pool->ai = pool->addrs;
pool_xmit(pool);
}
#endif /* WORKER */
#ifdef AUTOKEY
/*
* 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;
DPRINTF(1, ("key_expire: at %lu associd %d\n", current_time,
peer->associd));
}
#endif /* AUTOKEY */
/*
* 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 20e-9 /* minimum clock increment (s) */
#define MAXSTEP 1 /* maximum clock increment (s) */
#define MINCHANGES 12 /* minimum number of step samples */
#define MAXLOOPS ((int)(1. / MINSTEP)) /* avoid infinite loop */
/*
* 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, and to tolerate underlying system clocks which
* ensure each reading is strictly greater than prior readings while
* using an underlying stepping (not interpolated) clock.
*
* sys_tick and sys_precision represent the time to read the clock for
* systems with high-precision clocks, and the tick interval or step
* size for lower-precision stepping clocks.
*
* This routine also measures the time to read the clock on stepping
* system clocks by counting the number of readings between changes of
* the underlying clock. With either type of clock, the minimum time
* to read the clock is saved as sys_fuzz, and used to ensure the
* get_systime() readings always increase and are fuzzed below sys_fuzz.
*/
void
measure_precision(void)
{
/*
* With sys_fuzz set to zero, get_systime() fuzzing of low bits
* is effectively disabled. trunc_os_clock is FALSE to disable
* get_ostime() simulation of a low-precision system clock.
*/
set_sys_fuzz(0.);
trunc_os_clock = FALSE;
measured_tick = measure_tick_fuzz();
set_sys_tick_precision(measured_tick);
msyslog(LOG_INFO, "proto: precision = %.3f usec (%d)",
sys_tick * 1e6, sys_precision);
if (sys_fuzz < sys_tick) {
msyslog(LOG_NOTICE, "proto: fuzz beneath %.3f usec",
sys_fuzz * 1e6);
}
}
/*
* measure_tick_fuzz()
*
* measures the minimum time to read the clock (stored in sys_fuzz)
* and returns the tick, the larger of the minimum increment observed
* between successive clock readings and the time to read the clock.
*/
double
measure_tick_fuzz(void)
{
l_fp minstep; /* MINSTEP as l_fp */
l_fp val; /* current seconds fraction */
l_fp last; /* last seconds fraction */
l_fp ldiff; /* val - last */
double tick; /* computed tick value */
double diff;
long repeats;
long max_repeats;
int changes;
int i; /* log2 precision */
tick = MAXSTEP;
max_repeats = 0;
repeats = 0;
changes = 0;
DTOLFP(MINSTEP, &minstep);
get_systime(&last);
for (i = 0; i < MAXLOOPS && changes < MINCHANGES; i++) {
get_systime(&val);
ldiff = val;
L_SUB(&ldiff, &last);
last = val;
if (L_ISGT(&ldiff, &minstep)) {
max_repeats = max(repeats, max_repeats);
repeats = 0;
changes++;
LFPTOD(&ldiff, diff);
tick = min(diff, tick);
} else {
repeats++;
}
}
if (changes < MINCHANGES) {
msyslog(LOG_ERR, "Fatal error: precision could not be measured (MINSTEP too large?)");
exit(1);
}
if (0 == max_repeats) {
set_sys_fuzz(tick);
} else {
set_sys_fuzz(tick / max_repeats);
}
return tick;
}
void
set_sys_tick_precision(
double tick
)
{
int i;
if (tick > 1.) {
msyslog(LOG_ERR,
"unsupported tick %.3f > 1s ignored", tick);
return;
}
if (tick < measured_tick) {
msyslog(LOG_ERR,
"proto: tick %.3f less than measured tick %.3f, ignored",
tick, measured_tick);
return;
} else if (tick > measured_tick) {
trunc_os_clock = TRUE;
msyslog(LOG_NOTICE,
"proto: truncating system clock to multiples of %.9f",
tick);
}
sys_tick = tick;
/*
* Find the nearest power of two.
*/
for (i = 0; tick <= 1; i--)
tick *= 2;
if (tick - 1 > 1 - tick / 2)
i++;
sys_precision = (s_char)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.
*/
set_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;
measure_precision();
get_systime(&dummy);
sys_survivors = 0;
sys_manycastserver = 0;
sys_bclient = 0;
sys_bdelay = BDELAY_DEFAULT; /*[Bug 3031] delay cutoff */
sys_authenticate = 1;
sys_stattime = current_time;
orphwait = current_time + sys_orphwait;
proto_clr_stats();
for (i = 0; i < MAX_TTL; ++i)
sys_ttl[i] = (u_char)((i * 256) / MAX_TTL);
sys_ttlmax = (MAX_TTL - 1);
hardpps_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) */
select_loop(value);
break;
case PROTO_MONITOR: /* monitoring (monitor) */
if (value)
mon_start(MON_ON);
else {
mon_stop(MON_ON);
if (mon_enabled)
msyslog(LOG_WARNING,
"restrict: 'monitor' cannot be disabled while 'limited' is enabled");
}
break;
case PROTO_NTP: /* NTP discipline (ntp) */
ntp_enable = value;
break;
case PROTO_MODE7: /* mode7 management (ntpdc) */
ntp_mode7 = value;
break;
case PROTO_PPS: /* PPS discipline (pps) */
hardpps_enable = value;
break;
case PROTO_FILEGEN: /* statistics (stats) */
stats_control = value;
break;
/*
* tos command - arguments are double, sometimes cast to int
*/
case PROTO_BCPOLLBSTEP: /* Broadcast Poll Backstep gate (bcpollbstep) */
sys_bcpollbstep = (u_char)dvalue;
break;
case PROTO_BEACON: /* manycast beacon (beacon) */
sys_beacon = (int)dvalue;
break;
case PROTO_BROADDELAY: /* default broadcast delay (bdelay) */
sys_bdelay = (dvalue ? dvalue : BDELAY_DEFAULT);
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_ORPHWAIT: /* orphan wait (orphwait) */
orphwait -= sys_orphwait;
sys_orphwait = (dvalue >= 1) ? (int)dvalue : NTP_ORPHWAIT;
orphwait += sys_orphwait;
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;
/*
* Peer_clear Early policy choices
*/
case PROTO_PCEDIGEST: /* Digest */
peer_clear_digest_early = value;
break;
/*
* Unpeer Early policy choices
*/
case PROTO_UECRYPTO: /* Crypto */
unpeer_crypto_early = value;
break;
case PROTO_UECRYPTONAK: /* Crypto_NAK */
unpeer_crypto_nak_early = value;
break;
case PROTO_UEDIGEST: /* Digest */
unpeer_digest_early = value;
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;
sys_kodsent = 0;
sys_lamport = 0;
sys_tsrounding = 0;
}
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