1 /* $NetBSD: ntp_proto.c,v 1.20 2024/08/18 20:47:17 christos Exp $ */
2
3 /*
4 * ntp_proto.c - NTP version 4 protocol machinery
5 *
6 * ATTENTION: Get approval from Harlan on all changes to this file!
7 * (Harlan will be discussing these changes with Dave Mills.)
8 *
9 */
10 #ifdef HAVE_CONFIG_H
11 #include <config.h>
12 #endif
13
14 #include "ntpd.h"
15 #include "ntp_stdlib.h"
16 #include "ntp_unixtime.h"
17 #include "ntp_control.h"
18 #include "ntp_string.h"
19 #include "ntp_leapsec.h"
20 #include "ntp_psl.h"
21 #include "refidsmear.h"
22
23 #include <stdio.h>
24 #ifdef HAVE_LIBSCF_H
25 #include <libscf.h>
26 #endif
27 #ifdef HAVE_UNISTD_H
28 #include <unistd.h>
29 #endif
30
31 /* [Bug 3031] define automatic broadcastdelay cutoff preset */
32 #ifndef BDELAY_DEFAULT
33 # define BDELAY_DEFAULT (-0.050)
34 #endif
35
36 #define SRVFUZ_SHIFT 6 /* 64 seconds */
37 #define SRVRSP_FUZZ(x) \
38 do { \
39 x.l_uf = 0; \
40 x.l_ui &= ~((1 << SRVFUZ_SHIFT) - 1U); \
41 } while (FALSE)
42
43 /*
44 * This macro defines the authentication state. If x is 1 authentication
45 * is required; otherwise it is optional.
46 */
47 #define AUTH(x, y) ((x) ? (y) == AUTH_OK \
48 : (y) == AUTH_OK || (y) == AUTH_NONE)
49
50 typedef enum
51 auth_state {
52 AUTH_UNKNOWN = -1, /* Unknown */
53 AUTH_NONE, /* authentication not required */
54 AUTH_OK, /* authentication OK */
55 AUTH_ERROR, /* authentication error */
56 AUTH_CRYPTO /* crypto_NAK */
57 } auth_code;
58
59 /*
60 * Set up Kiss Code values
61 */
62
63 typedef enum
64 kiss_codes {
65 NOKISS, /* No Kiss Code */
66 RATEKISS, /* Rate limit Kiss Code */
67 DENYKISS, /* Deny Kiss */
68 RSTRKISS, /* Restricted Kiss */
69 XKISS /* Experimental Kiss */
70 } kiss_code;
71
72 typedef enum
73 nak_error_codes {
74 NONAK, /* No NAK seen */
75 INVALIDNAK, /* NAK cannot be used */
76 VALIDNAK /* NAK is valid */
77 } nak_code;
78
79 /*
80 * traffic shaping parameters
81 */
82 #define NTP_IBURST 6 /* packets in iburst */
83 #define RESP_DELAY 1 /* refclock burst delay (s) */
84
85 /*
86 * pool soliciting restriction duration (s)
87 */
88 #define POOL_SOLICIT_WINDOW 8
89
90 /*
91 * flag bits propagated from pool/manycast to individual peers
92 */
93 #define POOL_FLAG_PMASK (FLAG_IBURST | FLAG_NOSELECT)
94
95 /*
96 * peer_select groups statistics for a peer used by clock_select() and
97 * clock_cluster().
98 */
99 typedef struct peer_select_tag {
100 struct peer * peer;
101 double synch; /* sync distance */
102 double error; /* jitter */
103 double seljit; /* selection jitter */
104 } peer_select;
105
106 /*
107 * System variables are declared here. Unless specified otherwise, all
108 * times are in seconds.
109 */
110 u_char sys_leap; /* system leap indicator, use set_sys_leap() to change this */
111 u_char xmt_leap; /* leap indicator sent in client requests, set up by set_sys_leap() */
112 u_char sys_stratum; /* system stratum */
113 s_char sys_precision; /* local clock precision (log2 s) */
114 double sys_rootdelay; /* roundtrip delay to root (primary source) */
115 double sys_rootdisp; /* dispersion to root (primary source) */
116 double prev_rootdisp; /* previous root dispersion */
117 double p2_rootdisp; /* previous previous root dispersion */
118 u_int32 sys_refid; /* reference id (network byte order) */
119 l_fp sys_reftime; /* last update time */
120 l_fp prev_reftime; /* previous sys_reftime */
121 l_fp p2_reftime; /* previous previous sys_reftime */
122 u_long prev_time; /* "current_time" when saved prev_time */
123 u_long p2_time; /* previous prev_time */
124 struct peer *sys_peer; /* current peer */
125
126 #ifdef LEAP_SMEAR
127 struct leap_smear_info leap_smear;
128 #endif
129 int leap_sec_in_progress;
130
131 /*
132 * Rate controls. Leaky buckets are used to throttle the packet
133 * transmission rates in order to protect busy servers such as at NIST
134 * and USNO. There is a counter for each association and another for KoD
135 * packets. The association counter decrements each second, but not
136 * below zero. Each time a packet is sent the counter is incremented by
137 * a configurable value representing the average interval between
138 * packets. A packet is delayed as long as the counter is greater than
139 * zero. Note this does not affect the time value computations.
140 */
141 /*
142 * Nonspecified system state variables
143 */
144 int sys_bclient; /* broadcast client enable */
145 int sys_mclient; /* multicast client enable */
146 double sys_bdelay; /* broadcast client default delay */
147 int sys_authenticate; /* requre authentication for config */
148 l_fp sys_authdelay; /* authentication delay */
149 double sys_offset; /* current local clock offset */
150 double sys_mindisp = MINDISPERSE; /* minimum distance (s) */
151 double sys_maxdist = MAXDISTANCE; /* selection threshold */
152 double sys_jitter; /* system jitter */
153 u_long sys_epoch; /* last clock update time */
154 static double sys_clockhop; /* clockhop threshold */
155 static int leap_vote_ins; /* leap consensus for insert */
156 static int leap_vote_del; /* leap consensus for delete */
157 keyid_t sys_private; /* private value for session seed */
158 int sys_manycastserver; /* respond to manycast client pkts */
159 int ntp_mode7; /* respond to ntpdc (mode7) */
160 int peer_ntpdate; /* active peers in ntpdate mode */
161 int sys_survivors; /* truest of the truechimers */
162 char *sys_ident = NULL; /* identity scheme */
163
164 /*
165 * TOS and multicast mapping stuff
166 */
167 int sys_floor = 0; /* cluster stratum floor */
168 u_char sys_bcpollbstep = 0; /* Broadcast Poll backstep gate */
169 int sys_ceiling = STRATUM_UNSPEC - 1; /* cluster stratum ceiling */
170 int sys_minsane = 1; /* minimum candidates */
171 int sys_minclock = NTP_MINCLOCK; /* minimum candidates */
172 int sys_maxclock = NTP_MAXCLOCK; /* maximum candidates */
173 int sys_cohort = 0; /* cohort switch */
174 int sys_orphan = STRATUM_UNSPEC + 1; /* orphan stratum */
175 int sys_orphwait = NTP_ORPHWAIT; /* orphan wait */
176 int sys_beacon = BEACON; /* manycast beacon interval */
177 u_int sys_ttlmax; /* max ttl mapping vector index */
178 u_char sys_ttl[MAX_TTL]; /* ttl mapping vector */
179
180 /*
181 * Statistics counters - first the good, then the bad
182 */
183 u_long sys_stattime; /* elapsed time */
184 u_long sys_received; /* packets received */
185 u_long sys_processed; /* packets for this host */
186 u_long sys_newversion; /* current version */
187 u_long sys_oldversion; /* old version */
188 u_long sys_restricted; /* access denied */
189 u_long sys_badlength; /* bad length or format */
190 u_long sys_badauth; /* bad authentication */
191 u_long sys_declined; /* declined */
192 u_long sys_limitrejected; /* rate exceeded */
193 u_long sys_kodsent; /* KoD sent */
194
195 /*
196 * Mechanism knobs: how soon do we peer_clear() or unpeer()?
197 *
198 * The default way is "on-receipt". If this was a packet from a
199 * well-behaved source, on-receipt will offer the fastest recovery.
200 * If this was from a DoS attack, the default way makes it easier
201 * for a bad-guy to DoS us. So look and see what bites you harder
202 * and choose according to your environment.
203 */
204 int peer_clear_digest_early = 1; /* bad digest (TEST5) and Autokey */
205 int unpeer_crypto_early = 1; /* bad crypto (TEST9) */
206 int unpeer_crypto_nak_early = 1; /* crypto_NAK (TEST5) */
207 int unpeer_digest_early = 1; /* bad digest (TEST5) */
208
209 int dynamic_interleave = DYNAMIC_INTERLEAVE; /* Bug 2978 mitigation */
210
211 int kiss_code_check(u_char hisleap, u_char hisstratum, u_char hismode, u_int32 refid);
212 nak_code valid_NAK (struct peer *peer, struct recvbuf *rbufp, u_char hismode);
213 static double root_distance (struct peer *);
214 static void clock_combine (peer_select *, int, int);
215 static void peer_xmit (struct peer *);
216 static void fast_xmit (struct recvbuf *, int, keyid_t, int);
217 static void pool_xmit (struct peer *);
218 static void clock_update (struct peer *);
219 static void measure_precision(void);
220 static double measure_tick_fuzz(void);
221 static int local_refid (struct peer *);
222 static int peer_unfit (struct peer *);
223 #ifdef AUTOKEY
224 static int group_test (char *, char *);
225 #endif /* AUTOKEY */
226 #ifdef WORKER
227 void pool_name_resolved (int, int, void *, const char *,
228 const char *, const struct addrinfo *,
229 const struct addrinfo *);
230 #endif /* WORKER */
231
232 const char * amtoa (int am);
233
234
235 void
set_sys_leap(u_char new_sys_leap)236 set_sys_leap(
237 u_char new_sys_leap
238 )
239 {
240 sys_leap = new_sys_leap;
241 xmt_leap = sys_leap;
242
243 /*
244 * Under certain conditions we send faked leap bits to clients, so
245 * eventually change xmt_leap below, but never change LEAP_NOTINSYNC.
246 */
247 if (xmt_leap != LEAP_NOTINSYNC) {
248 if (leap_sec_in_progress) {
249 /* always send "not sync" */
250 xmt_leap = LEAP_NOTINSYNC;
251 }
252 #ifdef LEAP_SMEAR
253 else {
254 /*
255 * If leap smear is enabled in general we must
256 * never send a leap second warning to clients,
257 * so make sure we only send "in sync".
258 */
259 if (leap_smear.enabled)
260 xmt_leap = LEAP_NOWARNING;
261 }
262 #endif /* LEAP_SMEAR */
263 }
264 }
265
266
267 /*
268 * Kiss Code check
269 */
270 int
kiss_code_check(u_char hisleap,u_char hisstratum,u_char hismode,u_int32 refid)271 kiss_code_check(
272 u_char hisleap,
273 u_char hisstratum,
274 u_char hismode,
275 u_int32 refid
276 )
277 {
278
279 if ( hismode == MODE_SERVER
280 && hisleap == LEAP_NOTINSYNC
281 && hisstratum == STRATUM_UNSPEC) {
282 if(memcmp(&refid,"RATE", 4) == 0) {
283 return (RATEKISS);
284 } else if(memcmp(&refid,"DENY", 4) == 0) {
285 return (DENYKISS);
286 } else if(memcmp(&refid,"RSTR", 4) == 0) {
287 return (RSTRKISS);
288 } else if(memcmp(&refid,"X", 1) == 0) {
289 return (XKISS);
290 }
291 }
292 return (NOKISS);
293 }
294
295
296 /*
297 * Check that NAK is valid
298 */
299 nak_code
valid_NAK(struct peer * peer,struct recvbuf * rbufp,u_char hismode)300 valid_NAK(
301 struct peer *peer,
302 struct recvbuf *rbufp,
303 u_char hismode
304 )
305 {
306 int base_packet_length = MIN_V4_PKT_LEN;
307 int remainder_size;
308 struct pkt * rpkt;
309 int keyid;
310 l_fp p_org; /* origin timestamp */
311 const l_fp * myorg; /* selected peer origin */
312
313 /*
314 * Check to see if there is something beyond the basic packet
315 */
316 if (rbufp->recv_length == base_packet_length) {
317 return NONAK;
318 }
319
320 remainder_size = rbufp->recv_length - base_packet_length;
321 /*
322 * Is this a potential NAK?
323 */
324 if (remainder_size != 4) {
325 return NONAK;
326 }
327
328 /*
329 * Only server responses can contain NAK's
330 */
331
332 if (hismode != MODE_SERVER &&
333 hismode != MODE_ACTIVE &&
334 hismode != MODE_PASSIVE
335 ) {
336 return INVALIDNAK;
337 }
338
339 /*
340 * Make sure that the extra field in the packet is all zeros
341 */
342 rpkt = &rbufp->recv_pkt;
343 keyid = ntohl(((u_int32 *)rpkt)[base_packet_length / 4]);
344 if (keyid != 0) {
345 return INVALIDNAK;
346 }
347
348 /*
349 * During the first few packets of the autokey dance there will
350 * not (yet) be a keyid, but in this case FLAG_SKEY is set.
351 * So the NAK is invalid if either there's no peer, or
352 * if the keyid is 0 and FLAG_SKEY is not set.
353 */
354 if (!peer || (!peer->keyid && !(peer->flags & FLAG_SKEY))) {
355 return INVALIDNAK;
356 }
357
358 /*
359 * The ORIGIN must match, or this cannot be a valid NAK, either.
360 */
361
362 if (FLAG_LOOPNONCE & peer->flags) {
363 myorg = &peer->nonce;
364 } else {
365 if (peer->flip > 0) {
366 myorg = &peer->borg;
367 } else {
368 myorg = &peer->aorg;
369 }
370 }
371
372 NTOHL_FP(&rpkt->org, &p_org);
373
374 if (L_ISZERO(&p_org) ||
375 L_ISZERO( myorg) ||
376 !L_ISEQU(&p_org, myorg)) {
377 return INVALIDNAK;
378 }
379
380 /* If we ever passed all that checks, we should be safe. Well,
381 * as safe as we can ever be with an unauthenticated crypto-nak.
382 */
383 return VALIDNAK;
384 }
385
386
387 /*
388 * transmit - transmit procedure called by poll timeout
389 */
390 void
transmit(struct peer * peer)391 transmit(
392 struct peer *peer /* peer structure pointer */
393 )
394 {
395 u_char hpoll;
396
397 /*
398 * The polling state machine. There are two kinds of machines,
399 * those that never expect a reply (broadcast and manycast
400 * server modes) and those that do (all other modes). The dance
401 * is intricate...
402 */
403 hpoll = peer->hpoll;
404
405 /*
406 * If we haven't received anything (even if unsync) since last
407 * send, reset ppoll.
408 */
409 if (peer->outdate > peer->timelastrec && !peer->reach)
410 peer->ppoll = peer->maxpoll;
411
412 /*
413 * In broadcast mode the poll interval is never changed from
414 * minpoll.
415 */
416 if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) {
417 peer->outdate = current_time;
418 poll_update(peer, hpoll, 0);
419 if (sys_leap != LEAP_NOTINSYNC)
420 peer_xmit(peer);
421 return;
422 }
423
424 /*
425 * In manycast mode we start with unity ttl. The ttl is
426 * increased by one for each poll until either sys_maxclock
427 * servers have been found or the maximum ttl is reached. When
428 * sys_maxclock servers are found we stop polling until one or
429 * more servers have timed out or until less than sys_minclock
430 * associations turn up. In this case additional better servers
431 * are dragged in and preempt the existing ones. Once every
432 * sys_beacon seconds we are to transmit unconditionally, but
433 * this code is not quite right -- peer->unreach counts polls
434 * and is being compared with sys_beacon, so the beacons happen
435 * every sys_beacon polls.
436 */
437 if (peer->cast_flags & MDF_ACAST) {
438 peer->outdate = current_time;
439 poll_update(peer, hpoll, 0);
440 if (peer->unreach > sys_beacon) {
441 peer->unreach = 0;
442 peer->ttl = 0;
443 peer_xmit(peer);
444 } else if ( sys_survivors < sys_minclock
445 || peer_associations < sys_maxclock) {
446 if (peer->ttl < sys_ttlmax)
447 peer->ttl++;
448 peer_xmit(peer);
449 }
450 peer->unreach++;
451 return;
452 }
453
454 /*
455 * Pool associations transmit unicast solicitations when there
456 * are less than a hard limit of 2 * sys_maxclock associations,
457 * and either less than sys_minclock survivors or less than
458 * sys_maxclock associations. The hard limit prevents unbounded
459 * growth in associations if the system clock or network quality
460 * result in survivor count dipping below sys_minclock often.
461 * This was observed testing with pool, where sys_maxclock == 12
462 * resulted in 60 associations without the hard limit. A
463 * similar hard limit on manycastclient ephemeral associations
464 * may be appropriate.
465 */
466 if (peer->cast_flags & MDF_POOL) {
467 peer->outdate = current_time;
468 poll_update(peer, hpoll, 0);
469 if ( (peer_associations <= 2 * sys_maxclock)
470 && ( peer_associations < sys_maxclock
471 || sys_survivors < sys_minclock))
472 pool_xmit(peer);
473 return;
474 }
475
476 /* [Bug 3851] drop pool servers which can no longer be reached. */
477 if (MDF_PCLNT & peer->cast_flags) {
478 if ( (IS_IPV6(&peer->srcadr) && !nonlocal_v6_addr_up)
479 || !nonlocal_v4_addr_up) {
480 unpeer(peer);
481 return;
482 }
483 }
484
485 /*
486 * In unicast modes the dance is much more intricate. It is
487 * designed to back off whenever possible to minimize network
488 * traffic.
489 */
490 if (peer->burst == 0) {
491 u_char oreach;
492
493 /*
494 * Update the reachability status. If not heard for
495 * three consecutive polls, stuff infinity in the clock
496 * filter.
497 */
498 oreach = peer->reach;
499 peer->outdate = current_time;
500 peer->unreach++;
501 peer->reach <<= 1;
502 if (!peer->reach) {
503
504 /*
505 * Here the peer is unreachable. If it was
506 * previously reachable raise a trap. Send a
507 * burst if enabled.
508 */
509 clock_filter(peer, 0., 0., MAXDISPERSE);
510 if (oreach) {
511 peer_unfit(peer);
512 report_event(PEVNT_UNREACH, peer, NULL);
513 }
514 if ( (peer->flags & FLAG_IBURST)
515 && peer->retry == 0)
516 peer->retry = NTP_RETRY;
517 } else {
518
519 /*
520 * Here the peer is reachable. Send a burst if
521 * enabled and the peer is fit. Reset unreach
522 * for persistent and ephemeral associations.
523 * Unreach is also reset for survivors in
524 * clock_select().
525 */
526 hpoll = sys_poll;
527 if (!(peer->flags & FLAG_PREEMPT))
528 peer->unreach = 0;
529 if ( (peer->flags & FLAG_BURST)
530 && peer->retry == 0
531 && !peer_unfit(peer))
532 peer->retry = NTP_RETRY;
533 }
534
535 /*
536 * Watch for timeout. If ephemeral, toss the rascal;
537 * otherwise, bump the poll interval. Note the
538 * poll_update() routine will clamp it to maxpoll.
539 * If preemptible and we have more peers than maxclock,
540 * and this peer has the minimum score of preemptibles,
541 * demobilize.
542 */
543 if (peer->unreach >= NTP_UNREACH) {
544 hpoll++;
545 /* ephemeral: no FLAG_CONFIG nor FLAG_PREEMPT */
546 if (!(peer->flags & (FLAG_CONFIG | FLAG_PREEMPT))) {
547 report_event(PEVNT_RESTART, peer, "timeout");
548 peer_clear(peer, "TIME");
549 unpeer(peer);
550 return;
551 }
552 if ( (peer->flags & FLAG_PREEMPT)
553 && (peer_associations > sys_maxclock)
554 && score_all(peer)) {
555 report_event(PEVNT_RESTART, peer, "timeout");
556 peer_clear(peer, "TIME");
557 unpeer(peer);
558 return;
559 }
560 }
561 } else {
562 peer->burst--;
563 if (peer->burst == 0) {
564
565 /*
566 * If ntpdate mode and the clock has not been
567 * set and all peers have completed the burst,
568 * we declare a successful failure.
569 */
570 if (mode_ntpdate) {
571 peer_ntpdate--;
572 if (peer_ntpdate == 0) {
573 msyslog(LOG_NOTICE,
574 "ntpd: no servers found");
575 if (!msyslog_term)
576 printf(
577 "ntpd: no servers found\n");
578 exit (0);
579 }
580 }
581 }
582 }
583 if (peer->retry > 0)
584 peer->retry--;
585
586 /*
587 * Do not transmit if in broadcast client mode.
588 */
589 poll_update(peer, hpoll, (peer->hmode == MODE_CLIENT));
590 if (peer->hmode != MODE_BCLIENT)
591 peer_xmit(peer);
592
593 return;
594 }
595
596
597 #ifdef DEBUG
598 const char *
amtoa(int am)599 amtoa(
600 int am
601 )
602 {
603 char *bp;
604
605 switch(am) {
606 case AM_ERR: return "AM_ERR";
607 case AM_NOMATCH: return "AM_NOMATCH";
608 case AM_PROCPKT: return "AM_PROCPKT";
609 case AM_BCST: return "AM_BCST";
610 case AM_FXMIT: return "AM_FXMIT";
611 case AM_MANYCAST: return "AM_MANYCAST";
612 case AM_NEWPASS: return "AM_NEWPASS";
613 case AM_NEWBCL: return "AM_NEWBCL";
614 case AM_POSSBCL: return "AM_POSSBCL";
615 default:
616 LIB_GETBUF(bp);
617 snprintf(bp, LIB_BUFLENGTH, "AM_#%d", am);
618 return bp;
619 }
620 }
621 #endif /* DEBUG */
622
623
624 /*
625 * receive - receive procedure called for each packet received
626 */
627 void
receive(struct recvbuf * rbufp)628 receive(
629 struct recvbuf *rbufp
630 )
631 {
632 register struct peer *peer; /* peer structure pointer */
633 register struct pkt *pkt; /* receive packet pointer */
634 u_char hisversion; /* packet version */
635 u_char hisleap; /* packet leap indicator */
636 u_char hismode; /* packet mode */
637 u_char hisstratum; /* packet stratum */
638 r4addr r4a; /* address restrictions */
639 u_short restrict_mask; /* restrict bits */
640 const char *hm_str; /* hismode string */
641 int kissCode = NOKISS; /* Kiss Code */
642 int has_mac; /* length of MAC field */
643 int authlen; /* offset of MAC field */
644 auth_code is_authentic = AUTH_UNKNOWN; /* Was AUTH_NONE */
645 nak_code crypto_nak_test; /* result of crypto-NAK check */
646 int retcode = AM_NOMATCH; /* match code */
647 keyid_t skeyid = 0; /* key IDs */
648 u_int32 opcode = 0; /* extension field opcode */
649 sockaddr_u *dstadr_sin; /* active runway */
650 u_char cast_flags; /* MDF_* flags for newpeer() */
651 struct peer *peer2; /* aux peer structure pointer */
652 endpt *match_ep; /* newpeer() local address */
653 l_fp p_org; /* origin timestamp */
654 l_fp p_rec; /* receive timestamp */
655 l_fp p_xmt; /* transmit timestamp */
656 #ifdef DEBUG
657 const char *am_str; /* association match string */
658 #endif
659 #ifdef AUTOKEY
660 char hostname[NTP_MAXSTRLEN + 1];
661 char *groupname = NULL;
662 struct autokey *ap; /* autokey structure pointer */
663 int rval; /* cookie snatcher */
664 keyid_t pkeyid = 0, tkeyid = 0; /* key IDs */
665 #endif /* AUTOKEY */
666 #ifdef HAVE_NTP_SIGND
667 static unsigned char zero_key[16];
668 #endif /* HAVE_NTP_SIGND */
669
670 /*
671 * Note that there are many places we do not call record_raw_stats().
672 *
673 * We only want to call it *after* we've sent a response, or perhaps
674 * when we've decided to drop a packet.
675 */
676
677 /*
678 * Monitor the packet and get restrictions. Note that the packet
679 * length for control and private mode packets must be checked
680 * by the service routines. Some restrictions have to be handled
681 * later in order to generate a kiss-o'-death packet.
682 */
683 /*
684 * Bogus port check is before anything, since it probably
685 * reveals a clogging attack. Likewise the mimimum packet size
686 * of 2 bytes (for mode 6/7) must be checked first.
687 */
688 sys_received++;
689 if (0 == SRCPORT(&rbufp->recv_srcadr) || rbufp->recv_length < 2) {
690 sys_badlength++;
691 return; /* bogus port / length */
692 }
693 restrictions(&rbufp->recv_srcadr, &r4a);
694 restrict_mask = r4a.rflags;
695
696 pkt = &rbufp->recv_pkt;
697 hisversion = PKT_VERSION(pkt->li_vn_mode);
698 hismode = (int)PKT_MODE(pkt->li_vn_mode);
699
700 if (restrict_mask & RES_IGNORE) {
701 DPRINTF(2, ("receive: drop: RES_IGNORE\n"));
702 sys_restricted++;
703 return; /* ignore everything */
704 }
705 if (hismode == MODE_PRIVATE) {
706 if (!ntp_mode7 || (restrict_mask & RES_NOQUERY)) {
707 DPRINTF(2, ("receive: drop: !mode7 or RES_NOQUERY\n"));
708 sys_restricted++;
709 return; /* no query private */
710 }
711 process_private(rbufp, !(RES_NOMODIFY & restrict_mask));
712 return;
713 }
714 if (hismode == MODE_CONTROL) {
715 if (restrict_mask & RES_NOQUERY) {
716 DPRINTF(2, ("receive: drop: RES_NOQUERY\n"));
717 sys_restricted++;
718 return; /* no query control */
719 }
720 process_control(rbufp, restrict_mask);
721 return;
722 }
723 if (restrict_mask & RES_DONTSERVE) {
724 DPRINTF(2, ("receive: drop: RES_DONTSERVE\n"));
725 sys_restricted++;
726 return; /* no time serve */
727 }
728
729
730 /* If we arrive here, we should have a standard NTP packet. We
731 * check that the minimum size is available and fetch some more
732 * items from the packet once we can be sure they are indeed
733 * there.
734 */
735 if ((size_t)rbufp->recv_length < LEN_PKT_NOMAC) {
736 sys_badlength++;
737 return; /* bogus length */
738 }
739
740 hisleap = PKT_LEAP(pkt->li_vn_mode);
741 hisstratum = PKT_TO_STRATUM(pkt->stratum);
742 DEBUG_INSIST(0 != hisstratum); /* paranoia check PKT_TO_STRATUM result */
743 /* TODO: this should be in a unit test */
744 DPRINTF(1, ("receive: at %ld %s<-%s ippeerlimit %d mode %d iflags %s "
745 "restrict %s org 0x%x.%08x xmt 0x%x.%08x\n",
746 current_time, stoa(&rbufp->dstadr->sin),
747 stoa(&rbufp->recv_srcadr), r4a.ippeerlimit, hismode,
748 iflags_str(rbufp->dstadr->flags),
749 rflags_str(restrict_mask),
750 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
751 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
752
753 /*
754 * This is for testing. If restricted drop ten percent of
755 * surviving packets.
756 */
757 if (restrict_mask & RES_FLAKE) {
758 if (ntp_uurandom() < .1) {
759 DPRINTF(2, ("receive: drop: RES_FLAKE\n"));
760 sys_restricted++;
761 return; /* no flakeway */
762 }
763 }
764
765 /*
766 ** Format Layer Checks
767 **
768 ** Validate the packet format. The packet size, packet header,
769 ** and any extension field lengths are checked. We identify
770 ** the beginning of the MAC, to identify the upper limit of
771 ** of the hash computation.
772 **
773 ** In case of a format layer check violation, the packet is
774 ** discarded with no further processing.
775 */
776
777 /*
778 * Version check must be after the query packets, since they
779 * intentionally use an early version.
780 */
781 if (hisversion == NTP_VERSION) {
782 sys_newversion++; /* new version */
783 } else if ( !(restrict_mask & RES_VERSION)
784 && hisversion >= NTP_OLDVERSION) {
785 sys_oldversion++; /* previous version */
786 } else {
787 DPRINTF(2, ("receive: drop: RES_VERSION\n"));
788 sys_badlength++;
789 return; /* old version */
790 }
791
792 /*
793 * Figure out his mode and validate the packet. This has some
794 * legacy raunch that probably should be removed. In very early
795 * NTP versions mode 0 was equivalent to what later versions
796 * would interpret as client mode.
797 */
798 if (hismode == MODE_UNSPEC) {
799 if (hisversion == NTP_OLDVERSION) {
800 hismode = MODE_CLIENT;
801 } else {
802 DPRINTF(2, ("receive: drop: MODE_UNSPEC\n"));
803 sys_badlength++;
804 return; /* invalid mode */
805 }
806 }
807
808 /*
809 * Validate the poll interval in the packet.
810 * 0 probably indicates a data-minimized packet.
811 * A valid poll interval is required for RATEKISS, where
812 * a value of 0 is not allowed. We check for this below.
813 *
814 * There might be arguments against this check. If you have
815 * any of these arguments, please let us know.
816 *
817 * At this point, the packet cannot be a mode[67] packet.
818 */
819 if ( pkt->ppoll
820 && ( (NTP_MINPOLL > pkt->ppoll)
821 || (NTP_MAXPOLL < pkt->ppoll)
822 )
823 ) {
824 #ifdef BUG3870
825 DPRINTF(2, ("receive: drop: Invalid ppoll (%d) from %s\n",
826 pkt->ppoll, stoa(&rbufp->recv_srcadr)));
827 sys_badlength++;
828 return; /* invalid packet poll */
829 #else
830 DPRINTF(2, ("receive: info: Invalid ppoll (%d) from %s\n",
831 pkt->ppoll, stoa(&rbufp->recv_srcadr)));
832 #endif
833 }
834
835 /*
836 * Parse the extension field if present. We figure out whether
837 * an extension field is present by measuring the MAC size. If
838 * the number of words following the packet header is 0, no MAC
839 * is present and the packet is not authenticated. If 1, the
840 * packet is a crypto-NAK; if 3, the packet is authenticated
841 * with DES; if 5, the packet is authenticated with MD5; if 6,
842 * the packet is authenticated with SHA. If 2 or * 4, the packet
843 * is a runt and discarded forthwith. If greater than 6, an
844 * extension field is present, so we subtract the length of the
845 * field and go around again.
846 *
847 * Note the above description is lame. We should/could also check
848 * the two bytes that make up the EF type and subtype, and then
849 * check the two bytes that tell us the EF length. A legacy MAC
850 * has a 4 byte keyID, and for conforming symmetric keys its value
851 * must be <= 64k, meaning the top two bytes will always be zero.
852 * Since the EF Type of 0 is reserved/unused, there's no way a
853 * conforming legacy MAC could ever be misinterpreted as an EF.
854 *
855 * There is more, but this isn't the place to document it.
856 */
857
858 authlen = LEN_PKT_NOMAC;
859 has_mac = rbufp->recv_length - authlen;
860 while (has_mac > 0) {
861 u_int32 len;
862 #ifdef AUTOKEY
863 u_int32 hostlen;
864 struct exten *ep;
865 #endif /*AUTOKEY */
866
867 if (has_mac % 4 != 0 || has_mac < (int)MIN_MAC_LEN) {
868 DPRINTF(2, ("receive: drop: bad post-packet length\n"));
869 sys_badlength++;
870 return; /* bad length */
871 }
872 /*
873 * This next test is clearly wrong - it needlessly
874 * prohibits short EFs (which don't yet exist)
875 */
876 if (has_mac <= (int)MAX_MAC_LEN) {
877 skeyid = ntohl(((u_int32 *)pkt)[authlen / 4]);
878 break;
879
880 } else {
881 opcode = ntohl(((u_int32 *)pkt)[authlen / 4]);
882 len = opcode & 0xffff;
883 if ( len % 4 != 0
884 || len < 4
885 || (int)len + authlen > rbufp->recv_length) {
886 DPRINTF(2, ("receive: drop: bad EF length\n"));
887 sys_badlength++;
888 return; /* bad length */
889 }
890 #ifdef AUTOKEY
891 /*
892 * Extract calling group name for later. If
893 * sys_groupname is non-NULL, there must be
894 * a group name provided to elicit a response.
895 */
896 if ( (opcode & 0x3fff0000) == CRYPTO_ASSOC
897 && sys_groupname != NULL) {
898 ep = (struct exten *)&((u_int32 *)pkt)[authlen / 4];
899 hostlen = ntohl(ep->vallen);
900 if ( hostlen >= sizeof(hostname)
901 || hostlen > len -
902 offsetof(struct exten, pkt)) {
903 DPRINTF(2, ("receive: drop: bad autokey hostname length\n"));
904 sys_badlength++;
905 return; /* bad length */
906 }
907 memcpy(hostname, &ep->pkt, hostlen);
908 hostname[hostlen] = '\0';
909 groupname = strchr(hostname, '@');
910 if (groupname == NULL) {
911 DPRINTF(2, ("receive: drop: empty autokey groupname\n"));
912 sys_declined++;
913 return;
914 }
915 groupname++;
916 }
917 #endif /* AUTOKEY */
918 authlen += len;
919 has_mac -= len;
920 }
921 }
922
923 /*
924 * If has_mac is < 0 we had a malformed packet.
925 */
926 if (has_mac < 0) {
927 DPRINTF(2, ("receive: drop: post-packet under-read\n"));
928 sys_badlength++;
929 return; /* bad length */
930 }
931
932 /*
933 ** Packet Data Verification Layer
934 **
935 ** This layer verifies the packet data content. If
936 ** authentication is required, a MAC must be present.
937 ** If a MAC is present, it must validate.
938 ** Crypto-NAK? Look - a shiny thing!
939 **
940 ** If authentication fails, we're done.
941 */
942
943 /*
944 * If authentication is explicitly required, a MAC must be present.
945 */
946 if (restrict_mask & RES_DONTTRUST && has_mac == 0) {
947 DPRINTF(2, ("receive: drop: RES_DONTTRUST\n"));
948 sys_restricted++;
949 return; /* access denied */
950 }
951
952 /*
953 * Update the MRU list and finger the cloggers. It can be a
954 * little expensive, so turn it off for production use.
955 * RES_LIMITED and RES_KOD will be cleared in the returned
956 * restrict_mask unless one or both actions are warranted.
957 */
958 restrict_mask = ntp_monitor(rbufp, restrict_mask);
959 if (restrict_mask & RES_LIMITED) {
960 sys_limitrejected++;
961 if ( !(restrict_mask & RES_KOD)
962 || MODE_BROADCAST == hismode
963 || MODE_SERVER == hismode) {
964 if (MODE_SERVER == hismode) {
965 DPRINTF(1, ("Possibly self-induced rate limiting of MODE_SERVER from %s\n",
966 stoa(&rbufp->recv_srcadr)));
967 } else {
968 DPRINTF(2, ("receive: drop: RES_KOD\n"));
969 }
970 return; /* rate exceeded */
971 }
972 if (hismode == MODE_CLIENT) {
973 fast_xmit(rbufp, MODE_SERVER, skeyid,
974 restrict_mask);
975 } else {
976 fast_xmit(rbufp, MODE_ACTIVE, skeyid,
977 restrict_mask);
978 }
979 return; /* rate exceeded */
980 }
981 restrict_mask &= ~RES_KOD;
982
983 /*
984 * We have tossed out as many buggy packets as possible early in
985 * the game to reduce the exposure to a clogging attack. Now we
986 * have to burn some cycles to find the association and
987 * authenticate the packet if required. Note that we burn only
988 * digest cycles, again to reduce exposure. There may be no
989 * matching association and that's okay.
990 *
991 * More on the autokey mambo. Normally the local interface is
992 * found when the association was mobilized with respect to a
993 * designated remote address. We assume packets arriving from
994 * the remote address arrive via this interface and the local
995 * address used to construct the autokey is the unicast address
996 * of the interface. However, if the sender is a broadcaster,
997 * the interface broadcast address is used instead.
998 * Notwithstanding this technobabble, if the sender is a
999 * multicaster, the broadcast address is null, so we use the
1000 * unicast address anyway. Don't ask.
1001 */
1002
1003 peer = findpeer(rbufp, hismode, &retcode);
1004 dstadr_sin = &rbufp->dstadr->sin;
1005 NTOHL_FP(&pkt->org, &p_org);
1006 NTOHL_FP(&pkt->rec, &p_rec);
1007 NTOHL_FP(&pkt->xmt, &p_xmt);
1008 hm_str = modetoa(hismode);
1009 #ifdef DEBUG
1010 am_str = amtoa(retcode);
1011 #endif
1012
1013 /*
1014 * Authentication is conditioned by three switches:
1015 *
1016 * NOPEER (RES_NOPEER) do not mobilize an association unless
1017 * authenticated
1018 * NOTRUST (RES_DONTTRUST) do not allow access unless
1019 * authenticated (implies NOPEER)
1020 * enable (sys_authenticate) master NOPEER switch, by default
1021 * on
1022 *
1023 * The NOPEER and NOTRUST can be specified on a per-client basis
1024 * using the restrict command. The enable switch if on implies
1025 * NOPEER for all clients. There are four outcomes:
1026 *
1027 * NONE The packet has no MAC.
1028 * OK the packet has a MAC and authentication succeeds
1029 * ERROR the packet has a MAC and authentication fails
1030 * CRYPTO crypto-NAK. The MAC has four octets only.
1031 *
1032 * Note: The AUTH(x, y) macro is used to filter outcomes. If x
1033 * is zero, acceptable outcomes of y are NONE and OK. If x is
1034 * one, the only acceptable outcome of y is OK.
1035 */
1036 crypto_nak_test = valid_NAK(peer, rbufp, hismode);
1037
1038 /*
1039 * Drop any invalid crypto-NAKs
1040 */
1041 if (crypto_nak_test == INVALIDNAK) {
1042 report_event(PEVNT_AUTH, peer, "Invalid_NAK");
1043 if (0 != peer) {
1044 peer->badNAK++;
1045 }
1046 msyslog(LOG_ERR, "Invalid-NAK error at %ld %s<-%s",
1047 current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr));
1048 return;
1049 }
1050
1051 if (has_mac == 0) {
1052 restrict_mask &= ~RES_MSSNTP;
1053 is_authentic = AUTH_NONE; /* not required */
1054 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org 0x%x.%08x xmt 0x%x.%08x NOMAC\n",
1055 current_time, stoa(dstadr_sin),
1056 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
1057 authlen,
1058 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
1059 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
1060 } else if (crypto_nak_test == VALIDNAK) {
1061 restrict_mask &= ~RES_MSSNTP;
1062 is_authentic = AUTH_CRYPTO; /* crypto-NAK */
1063 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org 0x%x.%08x xmt 0x%x.%08x CRYPTONAK\n",
1064 current_time, stoa(dstadr_sin),
1065 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
1066 skeyid, authlen + has_mac, is_authentic,
1067 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
1068 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
1069
1070 #ifdef HAVE_NTP_SIGND
1071 /*
1072 * If the signature is 20 bytes long, the last 16 of
1073 * which are zero, then this is a Microsoft client
1074 * wanting AD-style authentication of the server's
1075 * reply.
1076 *
1077 * This is described in Microsoft's WSPP docs, in MS-SNTP:
1078 * http://msdn.microsoft.com/en-us/library/cc212930.aspx
1079 */
1080 } else if ( has_mac == MAX_MD5_LEN
1081 && (restrict_mask & RES_MSSNTP)
1082 && (retcode == AM_FXMIT || retcode == AM_NEWPASS)
1083 && (memcmp(zero_key, (char *)pkt + authlen + 4,
1084 MAX_MD5_LEN - 4) == 0)) {
1085 is_authentic = AUTH_NONE;
1086 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org %x.%08x xmt %x.%08x SIGND\n",
1087 current_time, stoa(dstadr_sin),
1088 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
1089 authlen,
1090 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
1091 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
1092 #endif /* HAVE_NTP_SIGND */
1093
1094 } else {
1095 /*
1096 * has_mac is not 0
1097 * Not a VALID_NAK
1098 * Not an MS-SNTP SIGND packet
1099 *
1100 * So there is a MAC here.
1101 */
1102
1103 restrict_mask &= ~RES_MSSNTP;
1104 #ifdef AUTOKEY
1105 /*
1106 * For autokey modes, generate the session key
1107 * and install in the key cache. Use the socket
1108 * broadcast or unicast address as appropriate.
1109 */
1110 if (crypto_flags && skeyid > NTP_MAXKEY) {
1111
1112 /*
1113 * More on the autokey dance (AKD). A cookie is
1114 * constructed from public and private values.
1115 * For broadcast packets, the cookie is public
1116 * (zero). For packets that match no
1117 * association, the cookie is hashed from the
1118 * addresses and private value. For server
1119 * packets, the cookie was previously obtained
1120 * from the server. For symmetric modes, the
1121 * cookie was previously constructed using an
1122 * agreement protocol; however, should PKI be
1123 * unavailable, we construct a fake agreement as
1124 * the EXOR of the peer and host cookies.
1125 *
1126 * hismode ephemeral persistent
1127 * =======================================
1128 * active 0 cookie#
1129 * passive 0% cookie#
1130 * client sys cookie 0%
1131 * server 0% sys cookie
1132 * broadcast 0 0
1133 *
1134 * # if unsync, 0
1135 * % can't happen
1136 */
1137 if (has_mac < (int)MAX_MD5_LEN) {
1138 DPRINTF(2, ("receive: drop: MD5 digest too short\n"));
1139 sys_badauth++;
1140 return;
1141 }
1142 if (hismode == MODE_BROADCAST) {
1143
1144 /*
1145 * For broadcaster, use the interface
1146 * broadcast address when available;
1147 * otherwise, use the unicast address
1148 * found when the association was
1149 * mobilized. However, if this is from
1150 * the wildcard interface, game over.
1151 */
1152 if ( crypto_flags
1153 && rbufp->dstadr ==
1154 ANY_INTERFACE_CHOOSE(&rbufp->recv_srcadr)) {
1155 DPRINTF(2, ("receive: drop: BCAST from wildcard\n"));
1156 sys_restricted++;
1157 return; /* no wildcard */
1158 }
1159 pkeyid = 0;
1160 if (!SOCK_UNSPEC(&rbufp->dstadr->bcast))
1161 dstadr_sin =
1162 &rbufp->dstadr->bcast;
1163 } else if (peer == NULL) {
1164 pkeyid = session_key(
1165 &rbufp->recv_srcadr, dstadr_sin, 0,
1166 sys_private, 0);
1167 } else {
1168 pkeyid = peer->pcookie;
1169 }
1170
1171 /*
1172 * The session key includes both the public
1173 * values and cookie. In case of an extension
1174 * field, the cookie used for authentication
1175 * purposes is zero. Note the hash is saved for
1176 * use later in the autokey mambo.
1177 */
1178 if (authlen > (int)LEN_PKT_NOMAC && pkeyid != 0) {
1179 session_key(&rbufp->recv_srcadr,
1180 dstadr_sin, skeyid, 0, 2);
1181 tkeyid = session_key(
1182 &rbufp->recv_srcadr, dstadr_sin,
1183 skeyid, pkeyid, 0);
1184 } else {
1185 tkeyid = session_key(
1186 &rbufp->recv_srcadr, dstadr_sin,
1187 skeyid, pkeyid, 2);
1188 }
1189
1190 }
1191 #endif /* AUTOKEY */
1192
1193 /*
1194 * Compute the cryptosum. Note a clogging attack may
1195 * succeed in bloating the key cache. If an autokey,
1196 * purge it immediately, since we won't be needing it
1197 * again. If the packet is authentic, it can mobilize an
1198 * association. Note that there is no key zero.
1199 */
1200 if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen,
1201 has_mac))
1202 is_authentic = AUTH_ERROR;
1203 else
1204 is_authentic = AUTH_OK;
1205 #ifdef AUTOKEY
1206 if (crypto_flags && skeyid > NTP_MAXKEY)
1207 authtrust(skeyid, 0);
1208 #endif /* AUTOKEY */
1209 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org 0x%x.%08x xmt 0x%x.%08x MAC\n",
1210 current_time, stoa(dstadr_sin),
1211 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str,
1212 skeyid, authlen + has_mac, is_authentic,
1213 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
1214 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)));
1215 }
1216
1217
1218 /*
1219 * Bug 3454:
1220 *
1221 * Now come at this from a different perspective:
1222 * - If we expect a MAC and it's not there, we drop it.
1223 * - If we expect one keyID and get another, we drop it.
1224 * - If we have a MAC ahd it hasn't been validated yet, try.
1225 * - if the provided MAC doesn't validate, we drop it.
1226 *
1227 * There might be more to this.
1228 */
1229 if (0 != peer && 0 != peer->keyid) {
1230 /* Should we msyslog() any of these? */
1231
1232 /*
1233 * This should catch:
1234 * - no keyID where one is expected,
1235 * - different keyID than what we expect.
1236 */
1237 if (peer->keyid != skeyid) {
1238 DPRINTF(2, ("receive: drop: Wanted keyID %d, got %d from %s\n",
1239 peer->keyid, skeyid,
1240 stoa(&rbufp->recv_srcadr)));
1241 sys_restricted++;
1242 return; /* drop: access denied */
1243 }
1244
1245 /*
1246 * if has_mac != 0 ...
1247 * - If it has not yet been validated, do so.
1248 * (under what circumstances might that happen?)
1249 * - if missing or bad MAC, log and drop.
1250 */
1251 if (0 != has_mac) {
1252 if (is_authentic == AUTH_UNKNOWN) {
1253 /* How can this happen? */
1254 DPRINTF(2, ("receive: 3454 check: AUTH_UNKNOWN from %s\n",
1255 stoa(&rbufp->recv_srcadr)));
1256 if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen,
1257 has_mac)) {
1258 /* MAC invalid or not found */
1259 is_authentic = AUTH_ERROR;
1260 } else {
1261 is_authentic = AUTH_OK;
1262 }
1263 }
1264 if (is_authentic != AUTH_OK) {
1265 DPRINTF(2, ("receive: drop: missing or bad MAC from %s\n",
1266 stoa(&rbufp->recv_srcadr)));
1267 sys_restricted++;
1268 return; /* drop: access denied */
1269 }
1270 }
1271 }
1272 /**/
1273
1274 /*
1275 ** On-Wire Protocol Layer
1276 **
1277 ** Verify protocol operations consistent with the on-wire protocol.
1278 ** The protocol discards bogus and duplicate packets as well as
1279 ** minimizes disruptions doe to protocol restarts and dropped
1280 ** packets. The operations are controlled by two timestamps:
1281 ** the transmit timestamp saved in the client state variables,
1282 ** and the origin timestamp in the server packet header. The
1283 ** comparison of these two timestamps is called the loopback test.
1284 ** The transmit timestamp functions as a nonce to verify that the
1285 ** response corresponds to the original request. The transmit
1286 ** timestamp also serves to discard replays of the most recent
1287 ** packet. Upon failure of either test, the packet is discarded
1288 ** with no further action.
1289 */
1290
1291 /*
1292 * The association matching rules are implemented by a set of
1293 * routines and an association table. A packet matching an
1294 * association is processed by the peer process for that
1295 * association. If there are no errors, an ephemeral association
1296 * is mobilized: a broadcast packet mobilizes a broadcast client
1297 * aassociation; a manycast server packet mobilizes a manycast
1298 * client association; a symmetric active packet mobilizes a
1299 * symmetric passive association.
1300 */
1301 DPRINTF(1, ("receive: MATCH_ASSOC dispatch: mode %d/%s:%s \n",
1302 hismode, hm_str, am_str));
1303 switch (retcode) {
1304
1305 /*
1306 * This is a client mode packet not matching any association. If
1307 * an ordinary client, simply toss a server mode packet back
1308 * over the fence. If a manycast client, we have to work a
1309 * little harder.
1310 *
1311 * There are cases here where we do not call record_raw_stats().
1312 */
1313 case AM_FXMIT:
1314
1315 /*
1316 * If authentication OK, send a server reply; otherwise,
1317 * send a crypto-NAK.
1318 */
1319 if (!(rbufp->dstadr->flags & INT_MCASTOPEN)) {
1320 /* HMS: would be nice to log FAST_XMIT|BADAUTH|RESTRICTED */
1321 record_raw_stats(&rbufp->recv_srcadr,
1322 &rbufp->dstadr->sin,
1323 &p_org, &p_rec, &p_xmt, &rbufp->recv_time,
1324 PKT_LEAP(pkt->li_vn_mode),
1325 PKT_VERSION(pkt->li_vn_mode),
1326 PKT_MODE(pkt->li_vn_mode),
1327 PKT_TO_STRATUM(pkt->stratum),
1328 pkt->ppoll,
1329 pkt->precision,
1330 FPTOD(NTOHS_FP(pkt->rootdelay)),
1331 FPTOD(NTOHS_FP(pkt->rootdisp)),
1332 pkt->refid,
1333 rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten);
1334
1335 if (AUTH(restrict_mask & RES_DONTTRUST,
1336 is_authentic)) {
1337 /* Bug 3596: Do we want to fuzz the reftime? */
1338 fast_xmit(rbufp, MODE_SERVER, skeyid,
1339 restrict_mask);
1340 } else if (is_authentic == AUTH_ERROR) {
1341 /* Bug 3596: Do we want to fuzz the reftime? */
1342 fast_xmit(rbufp, MODE_SERVER, 0,
1343 restrict_mask);
1344 sys_badauth++;
1345 } else {
1346 DPRINTF(2, ("receive: AM_FXMIT drop: !mcast restricted\n"));
1347 sys_restricted++;
1348 }
1349
1350 return; /* hooray */
1351 }
1352
1353 /*
1354 * This must be manycast. Do not respond if not
1355 * configured as a manycast server.
1356 */
1357 if (!sys_manycastserver) {
1358 DPRINTF(2, ("receive: AM_FXMIT drop: Not manycastserver\n"));
1359 sys_restricted++;
1360 return; /* not enabled */
1361 }
1362
1363 #ifdef AUTOKEY
1364 /*
1365 * Do not respond if not the same group.
1366 */
1367 if (group_test(groupname, NULL)) {
1368 DPRINTF(2, ("receive: AM_FXMIT drop: empty groupname\n"));
1369 sys_declined++;
1370 return;
1371 }
1372 #endif /* AUTOKEY */
1373
1374 /*
1375 * Do not respond if we are not synchronized or our
1376 * stratum is greater than the manycaster or the
1377 * manycaster has already synchronized to us.
1378 */
1379 if ( sys_leap == LEAP_NOTINSYNC
1380 || sys_stratum >= hisstratum
1381 || (!sys_cohort && sys_stratum == hisstratum + 1)
1382 || rbufp->dstadr->addr_refid == pkt->refid
1383 # ifdef WORDS_BIGENDIAN /* see local_refid() comment */
1384 || ( IS_IPV6(&rbufp->dstadr->sin)
1385 &&rbufp->dstadr->old_refid == pkt->refid)
1386 # endif
1387 ) {
1388 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));
1389 DPRINTF(2, ("receive: AM_FXMIT drop: LEAP_NOTINSYNC || stratum || loop\n"));
1390 sys_declined++;
1391 return; /* no help */
1392 }
1393
1394 /*
1395 * Do not respond if the packet came into an IPv6 link-local
1396 * address on an interface where we also have a usable
1397 * global address, to avoid duplicate associations.
1398 */
1399 if (INT_LL_OF_GLOB & rbufp->dstadr->flags) {
1400 DPRINTF(2, ("receive: declining manycast solicitation on link-local IPv6\n"));
1401 sys_declined++;
1402 return;
1403 }
1404
1405 /*
1406 * Respond only if authentication succeeds. Don't do a
1407 * crypto-NAK, as that would not be useful.
1408 */
1409 if (AUTH(restrict_mask & RES_DONTTRUST, is_authentic)) {
1410 record_raw_stats(&rbufp->recv_srcadr,
1411 &rbufp->dstadr->sin,
1412 &p_org, &p_rec, &p_xmt, &rbufp->recv_time,
1413 PKT_LEAP(pkt->li_vn_mode),
1414 PKT_VERSION(pkt->li_vn_mode),
1415 PKT_MODE(pkt->li_vn_mode),
1416 PKT_TO_STRATUM(pkt->stratum),
1417 pkt->ppoll,
1418 pkt->precision,
1419 FPTOD(NTOHS_FP(pkt->rootdelay)),
1420 FPTOD(NTOHS_FP(pkt->rootdisp)),
1421 pkt->refid,
1422 rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten);
1423
1424 /* Bug 3596: Do we want to fuzz the reftime? */
1425 fast_xmit(rbufp, MODE_SERVER, skeyid,
1426 restrict_mask);
1427 }
1428 return; /* hooray */
1429
1430 /*
1431 * This is a server mode packet returned in response to a client
1432 * mode packet sent to a multicast group address (for
1433 * manycastclient) or to a unicast address (for pool). The
1434 * origin timestamp is a good nonce to reliably associate the
1435 * reply with what was sent. If there is no match, that's
1436 * curious and could be an intruder attempting to clog, so we
1437 * just ignore it.
1438 *
1439 * If the packet is authentic and the manycastclient or pool
1440 * association is found, we mobilize a client association and
1441 * copy pertinent variables from the manycastclient or pool
1442 * association to the new client association. If not, just
1443 * ignore the packet.
1444 *
1445 * There is an implosion hazard at the manycast client, since
1446 * the manycast servers send the server packet immediately. If
1447 * the guy is already here, don't fire up a duplicate.
1448 *
1449 * There are cases here where we do not call record_raw_stats().
1450 */
1451 case AM_MANYCAST:
1452
1453 #ifdef AUTOKEY
1454 /*
1455 * Do not respond if not the same group.
1456 */
1457 if (group_test(groupname, NULL)) {
1458 DPRINTF(2, ("receive: AM_MANYCAST drop: empty groupname\n"));
1459 sys_declined++;
1460 return;
1461 }
1462 #endif /* AUTOKEY */
1463 /* Do not spin up duplicate manycast associations */
1464 if (INT_LL_OF_GLOB & rbufp->dstadr->flags) {
1465 DPRINTF(2, ("receive: AM_MANYCAST drop: link-local server\n"));
1466 sys_declined++;
1467 return;
1468 }
1469 if ((peer2 = findmanycastpeer(rbufp)) == NULL) {
1470 DPRINTF(2, ("receive: AM_MANYCAST drop: No manycast peer\n"));
1471 sys_restricted++;
1472 return; /* not enabled */
1473 }
1474 if (!AUTH( (!(peer2->cast_flags & MDF_POOL)
1475 && sys_authenticate)
1476 || (restrict_mask & (RES_NOPEER |
1477 RES_DONTTRUST)), is_authentic)
1478 /* MC: RES_NOEPEER? */
1479 ) {
1480 DPRINTF(2, ("receive: AM_MANYCAST drop: bad auth || (NOPEER|DONTTRUST)\n"));
1481 sys_restricted++;
1482 return; /* access denied */
1483 }
1484
1485 /*
1486 * Do not respond if unsynchronized or stratum is below
1487 * the floor or at or above the ceiling.
1488 */
1489 if ( hisleap == LEAP_NOTINSYNC
1490 || hisstratum < sys_floor
1491 || hisstratum >= sys_ceiling) {
1492 DPRINTF(2, ("receive: AM_MANYCAST drop: unsync/stratum\n"));
1493 sys_declined++;
1494 return; /* no help */
1495 }
1496 cast_flags = MDF_UCAST;
1497 if (MDF_POOL & peer2->cast_flags) {
1498 cast_flags |= MDF_PCLNT;
1499 }
1500 peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr,
1501 r4a.ippeerlimit, MODE_CLIENT, hisversion,
1502 peer2->minpoll, peer2->maxpoll,
1503 (FLAG_PREEMPT | (POOL_FLAG_PMASK & peer2->flags)),
1504 cast_flags, 0, skeyid, sys_ident);
1505 if (NULL == peer) {
1506 DPRINTF(2, ("receive: AM_MANYCAST drop: duplicate\n"));
1507 sys_declined++;
1508 return; /* ignore duplicate */
1509 }
1510
1511 /*
1512 * After each ephemeral pool association is spun,
1513 * accelerate the next poll for the pool solicitor so
1514 * the pool will fill promptly.
1515 */
1516 if (peer2->cast_flags & MDF_POOL)
1517 peer2->nextdate = current_time + 1;
1518
1519 /*
1520 * Further processing of the solicitation response would
1521 * simply detect its origin timestamp as bogus for the
1522 * brand-new association (it matches the prototype
1523 * association) and tinker with peer->nextdate delaying
1524 * first sync.
1525 */
1526 return; /* solicitation response handled */
1527
1528 /*
1529 * This is the first packet received from a broadcast server. If
1530 * the packet is authentic and we are enabled as broadcast
1531 * client, mobilize a broadcast client association. We don't
1532 * kiss any frogs here.
1533 *
1534 * There are cases here where we do not call record_raw_stats().
1535 */
1536 case AM_NEWBCL:
1537
1538 #ifdef AUTOKEY
1539 /*
1540 * Do not respond if not the same group.
1541 */
1542 if (group_test(groupname, sys_ident)) {
1543 DPRINTF(2, ("receive: AM_NEWBCL drop: groupname mismatch\n"));
1544 sys_declined++;
1545 return;
1546 }
1547 #endif /* AUTOKEY */
1548 if (!sys_bclient && !sys_mclient) {
1549 DPRINTF(2, ("receive: AM_NEWBCL drop: not a bclient/mclient\n"));
1550 sys_restricted++;
1551 return; /* not enabled */
1552 }
1553 if (!AUTH(sys_authenticate | (restrict_mask &
1554 (RES_NOPEER | RES_DONTTRUST)), is_authentic)
1555 /* NEWBCL: RES_NOEPEER? */
1556 ) {
1557 DPRINTF(2, ("receive: AM_NEWBCL drop: AUTH failed\n"));
1558 sys_restricted++;
1559 return; /* access denied */
1560 }
1561
1562 /*
1563 * Do not respond if unsynchronized or stratum is below
1564 * the floor or at or above the ceiling.
1565 */
1566 if ( hisleap == LEAP_NOTINSYNC
1567 || hisstratum < sys_floor
1568 || hisstratum >= sys_ceiling) {
1569 DPRINTF(2, ("receive: AM_NEWBCL drop: Unsync or bad stratum\n"));
1570 sys_declined++;
1571 return; /* no help */
1572 }
1573
1574 #ifdef AUTOKEY
1575 /*
1576 * Do not respond if Autokey and the opcode is not a
1577 * CRYPTO_ASSOC response with association ID.
1578 */
1579 if ( crypto_flags && skeyid > NTP_MAXKEY
1580 && (opcode & 0xffff0000) != (CRYPTO_ASSOC | CRYPTO_RESP)) {
1581 DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not CRYPTO_ASSOC\n"));
1582 sys_declined++;
1583 return; /* protocol error */
1584 }
1585 #endif /* AUTOKEY */
1586
1587 /*
1588 * Broadcasts received via a multicast address may
1589 * arrive after a unicast volley has begun
1590 * with the same remote address. newpeer() will not
1591 * find duplicate associations on other local endpoints
1592 * if a non-NULL endpoint is supplied. multicastclient
1593 * ephemeral associations are unique across all local
1594 * endpoints.
1595 */
1596 if (!(INT_MCASTOPEN & rbufp->dstadr->flags))
1597 match_ep = rbufp->dstadr;
1598 else
1599 match_ep = NULL;
1600
1601 /*
1602 * Determine whether to execute the initial volley.
1603 */
1604 if (sys_bdelay > 0.0) {
1605 #ifdef AUTOKEY
1606 /*
1607 * If a two-way exchange is not possible,
1608 * neither is Autokey.
1609 */
1610 if (crypto_flags && skeyid > NTP_MAXKEY) {
1611 sys_restricted++;
1612 DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not 2-way\n"));
1613 return; /* no autokey */
1614 }
1615 #endif /* AUTOKEY */
1616
1617 /*
1618 * Do not execute the volley. Start out in
1619 * broadcast client mode.
1620 */
1621 peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep,
1622 r4a.ippeerlimit, MODE_BCLIENT, hisversion,
1623 pkt->ppoll, pkt->ppoll,
1624 FLAG_PREEMPT, MDF_BCLNT, 0, skeyid, sys_ident);
1625 if (NULL == peer) {
1626 DPRINTF(2, ("receive: AM_NEWBCL drop: duplicate\n"));
1627 sys_restricted++;
1628 return; /* ignore duplicate */
1629
1630 } else {
1631 peer->delay = sys_bdelay;
1632 peer->bxmt = p_xmt;
1633 }
1634 break;
1635 }
1636
1637 /*
1638 * Execute the initial volley in order to calibrate the
1639 * propagation delay and run the Autokey protocol.
1640 *
1641 * Note that the minpoll is taken from the broadcast
1642 * packet, normally 6 (64 s) and that the poll interval
1643 * is fixed at this value.
1644 */
1645 peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep,
1646 r4a.ippeerlimit, MODE_CLIENT, hisversion,
1647 pkt->ppoll, pkt->ppoll,
1648 FLAG_BC_VOL | FLAG_IBURST | FLAG_PREEMPT, MDF_BCLNT,
1649 0, skeyid, sys_ident);
1650 if (NULL == peer) {
1651 DPRINTF(2, ("receive: AM_NEWBCL drop: empty newpeer() failed\n"));
1652 sys_restricted++;
1653 return; /* ignore duplicate */
1654 }
1655 peer->bxmt = p_xmt;
1656 #ifdef AUTOKEY
1657 if (skeyid > NTP_MAXKEY)
1658 crypto_recv(peer, rbufp);
1659 #endif /* AUTOKEY */
1660
1661 return; /* hooray */
1662
1663 /*
1664 * This is the first packet received from a potential ephemeral
1665 * symmetric active peer. First, deal with broken Windows clients.
1666 * Then, if NOEPEER is enabled, drop it. If the packet meets our
1667 * authenticty requirements and is the first he sent, mobilize
1668 * a passive association.
1669 * Otherwise, kiss the frog.
1670 *
1671 * There are cases here where we do not call record_raw_stats().
1672 */
1673 case AM_NEWPASS:
1674
1675 DEBUG_REQUIRE(MODE_ACTIVE == hismode);
1676
1677 #ifdef AUTOKEY
1678 /*
1679 * Do not respond if not the same group.
1680 */
1681 if (group_test(groupname, sys_ident)) {
1682 DPRINTF(2, ("receive: AM_NEWPASS drop: Autokey group mismatch\n"));
1683 sys_declined++;
1684 return;
1685 }
1686 #endif /* AUTOKEY */
1687 if (!AUTH(sys_authenticate | (restrict_mask &
1688 (RES_NOPEER | RES_DONTTRUST)), is_authentic)
1689 ) {
1690 /*
1691 * If authenticated but cannot mobilize an
1692 * association, send a symmetric passive
1693 * response without mobilizing an association.
1694 * This is for drat broken Windows clients. See
1695 * Microsoft KB 875424 for preferred workaround.
1696 */
1697 if (AUTH(restrict_mask & RES_DONTTRUST,
1698 is_authentic)) {
1699 fast_xmit(rbufp, MODE_PASSIVE, skeyid,
1700 restrict_mask);
1701 return; /* hooray */
1702 }
1703 /* HMS: Why is this next set of lines a feature? */
1704 if (is_authentic == AUTH_ERROR) {
1705 fast_xmit(rbufp, MODE_PASSIVE, 0,
1706 restrict_mask);
1707 sys_restricted++;
1708 return;
1709 }
1710
1711 if (restrict_mask & RES_NOEPEER) {
1712 DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n"));
1713 sys_declined++;
1714 return;
1715 }
1716
1717 /* [Bug 2941]
1718 * If we got here, the packet isn't part of an
1719 * existing association, either isn't correctly
1720 * authenticated or it is but we are refusing
1721 * ephemeral peer requests, and it didn't meet
1722 * either of the previous two special cases so we
1723 * should just drop it on the floor. For example,
1724 * crypto-NAKs (is_authentic == AUTH_CRYPTO)
1725 * will make it this far. This is just
1726 * debug-printed and not logged to avoid log
1727 * flooding.
1728 */
1729 DPRINTF(2, ("receive: at %ld refusing to mobilize passive association"
1730 " with unknown peer %s mode %d/%s:%s keyid %08x len %d auth %d\n",
1731 current_time, stoa(&rbufp->recv_srcadr),
1732 hismode, hm_str, am_str, skeyid,
1733 (authlen + has_mac), is_authentic));
1734 sys_declined++;
1735 return;
1736 }
1737
1738 if (restrict_mask & RES_NOEPEER) {
1739 DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n"));
1740 sys_declined++;
1741 return;
1742 }
1743
1744 /*
1745 * Do not respond if synchronized and if stratum is
1746 * below the floor or at or above the ceiling. Note,
1747 * this allows an unsynchronized peer to synchronize to
1748 * us. It would be very strange if he did and then was
1749 * nipped, but that could only happen if we were
1750 * operating at the top end of the range. It also means
1751 * we will spin an ephemeral association in response to
1752 * MODE_ACTIVE KoDs, which will time out eventually.
1753 */
1754 if ( hisleap != LEAP_NOTINSYNC
1755 && (hisstratum < sys_floor || hisstratum >= sys_ceiling)) {
1756 DPRINTF(2, ("receive: AM_NEWPASS drop: Remote stratum (%d) out of range\n",
1757 hisstratum));
1758 sys_declined++;
1759 return; /* no help */
1760 }
1761
1762 /*
1763 * The message is correctly authenticated and allowed.
1764 * Mobilize a symmetric passive association, if we won't
1765 * exceed the ippeerlimit.
1766 */
1767 if ((peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr,
1768 r4a.ippeerlimit, MODE_PASSIVE, hisversion,
1769 pkt->ppoll, NTP_MAXDPOLL, 0, MDF_UCAST, 0,
1770 skeyid, sys_ident)) == NULL) {
1771 DPRINTF(2, ("receive: AM_NEWPASS drop: newpeer() failed\n"));
1772 sys_declined++;
1773 return; /* ignore duplicate */
1774 }
1775 break;
1776
1777
1778 /*
1779 * Process regular packet. Nothing special.
1780 *
1781 * There are cases here where we do not call record_raw_stats().
1782 */
1783 case AM_PROCPKT:
1784
1785 #ifdef AUTOKEY
1786 /*
1787 * Do not respond if not the same group.
1788 */
1789 if (group_test(groupname, peer->ident)) {
1790 DPRINTF(2, ("receive: AM_PROCPKT drop: Autokey group mismatch\n"));
1791 sys_declined++;
1792 return;
1793 }
1794 #endif /* AUTOKEY */
1795
1796 if (MODE_BROADCAST == hismode) {
1797 int bail = 0;
1798 l_fp tdiff;
1799 u_long deadband;
1800
1801 DPRINTF(2, ("receive: PROCPKT/BROADCAST: prev pkt %ld seconds ago, ppoll: %d, %d secs\n",
1802 (current_time - peer->timelastrec),
1803 peer->ppoll, (1 << peer->ppoll)
1804 ));
1805 /* Things we can check:
1806 *
1807 * Did the poll interval change?
1808 * Is the poll interval in the packet in-range?
1809 * Did this packet arrive too soon?
1810 * Is the timestamp in this packet monotonic
1811 * with respect to the previous packet?
1812 */
1813
1814 /* This is noteworthy, not error-worthy */
1815 if (pkt->ppoll != peer->ppoll) {
1816 msyslog(LOG_INFO, "receive: broadcast poll from %s changed from %u to %u",
1817 stoa(&rbufp->recv_srcadr),
1818 peer->ppoll, pkt->ppoll);
1819 }
1820
1821 /* This is error-worthy */
1822 if ( pkt->ppoll < peer->minpoll
1823 || pkt->ppoll > peer->maxpoll) {
1824 msyslog(LOG_INFO, "receive: broadcast poll of %u from %s is out-of-range (%d to %d)!",
1825 pkt->ppoll, stoa(&rbufp->recv_srcadr),
1826 peer->minpoll, peer->maxpoll);
1827 ++bail;
1828 }
1829
1830 /* too early? worth an error, too!
1831 *
1832 * [Bug 3113] Ensure that at least one poll
1833 * interval has elapsed since the last **clean**
1834 * packet was received. We limit the check to
1835 * **clean** packets to prevent replayed packets
1836 * and incorrectly authenticated packets, which
1837 * we'll discard, from being used to create a
1838 * denial of service condition.
1839 */
1840 deadband = (1u << pkt->ppoll);
1841 if (FLAG_BC_VOL & peer->flags)
1842 deadband -= 3; /* allow greater fuzz after volley */
1843 if ((current_time - peer->timereceived) < deadband) {
1844 msyslog(LOG_INFO, "receive: broadcast packet from %s arrived after %lu, not %lu seconds!",
1845 stoa(&rbufp->recv_srcadr),
1846 (current_time - peer->timereceived),
1847 deadband);
1848 ++bail;
1849 }
1850
1851 /* Alert if time from the server is non-monotonic.
1852 *
1853 * [Bug 3114] is about Broadcast mode replay DoS.
1854 *
1855 * Broadcast mode *assumes* a trusted network.
1856 * Even so, it's nice to be robust in the face
1857 * of attacks.
1858 *
1859 * If we get an authenticated broadcast packet
1860 * with an "earlier" timestamp, it means one of
1861 * two things:
1862 *
1863 * - the broadcast server had a backward step.
1864 *
1865 * - somebody is trying a replay attack.
1866 *
1867 * deadband: By default, we assume the broadcast
1868 * network is trustable, so we take our accepted
1869 * broadcast packets as we receive them. But
1870 * some folks might want to take additional poll
1871 * delays before believing a backward step.
1872 */
1873 if (sys_bcpollbstep) {
1874 /* pkt->ppoll or peer->ppoll ? */
1875 deadband = (1u << pkt->ppoll)
1876 * sys_bcpollbstep + 2;
1877 } else {
1878 deadband = 0;
1879 }
1880
1881 if (L_ISZERO(&peer->bxmt)) {
1882 tdiff.l_ui = tdiff.l_uf = 0;
1883 } else {
1884 tdiff = p_xmt;
1885 L_SUB(&tdiff, &peer->bxmt);
1886 }
1887 if ( tdiff.l_i < 0
1888 && (current_time - peer->timereceived) < deadband)
1889 {
1890 msyslog(LOG_INFO, "receive: broadcast packet from %s contains non-monotonic timestamp: 0x%x.%08x -> 0x%x.%08x",
1891 stoa(&rbufp->recv_srcadr),
1892 peer->bxmt.l_ui, peer->bxmt.l_uf,
1893 p_xmt.l_ui, p_xmt.l_uf
1894 );
1895 ++bail;
1896 }
1897
1898 if (bail) {
1899 DPRINTF(2, ("receive: AM_PROCPKT drop: bail\n"));
1900 peer->timelastrec = current_time;
1901 sys_declined++;
1902 return;
1903 }
1904 }
1905
1906 break;
1907
1908 /*
1909 * A passive packet matches a passive association. This is
1910 * usually the result of reconfiguring a client on the fly. As
1911 * this association might be legitimate and this packet an
1912 * attempt to deny service, just ignore it.
1913 */
1914 case AM_ERR:
1915 DPRINTF(2, ("receive: AM_ERR drop.\n"));
1916 sys_declined++;
1917 return;
1918
1919 /*
1920 * For everything else there is the bit bucket.
1921 */
1922 default:
1923 DPRINTF(2, ("receive: default drop.\n"));
1924 sys_declined++;
1925 return;
1926 }
1927
1928 #ifdef AUTOKEY
1929 /*
1930 * If the association is configured for Autokey, the packet must
1931 * have a public key ID; if not, the packet must have a
1932 * symmetric key ID.
1933 */
1934 if ( is_authentic != AUTH_CRYPTO
1935 && ( ((peer->flags & FLAG_SKEY) && skeyid <= NTP_MAXKEY)
1936 || (!(peer->flags & FLAG_SKEY) && skeyid > NTP_MAXKEY))) {
1937 DPRINTF(2, ("receive: drop: Autokey but wrong/bad auth\n"));
1938 sys_badauth++;
1939 return;
1940 }
1941 #endif /* AUTOKEY */
1942
1943 peer->received++;
1944 peer->flash &= ~PKT_TEST_MASK;
1945 if (peer->flags & FLAG_XBOGUS) {
1946 peer->flags &= ~FLAG_XBOGUS;
1947 peer->flash |= TEST3;
1948 }
1949
1950 /*
1951 * Next comes a rigorous schedule of timestamp checking. If the
1952 * transmit timestamp is zero, the server has not initialized in
1953 * interleaved modes or is horribly broken.
1954 *
1955 * A KoD packet we pay attention to cannot have a 0 transmit
1956 * timestamp.
1957 */
1958
1959 kissCode = kiss_code_check(hisleap, hisstratum, hismode, pkt->refid);
1960
1961 if (L_ISZERO(&p_xmt)) {
1962 peer->flash |= TEST3; /* unsynch */
1963 if (kissCode != NOKISS) { /* KoD packet */
1964 peer->bogusorg++; /* for TEST2 or TEST3 */
1965 msyslog(LOG_INFO,
1966 "receive: Unexpected zero transmit timestamp in KoD from %s",
1967 ntoa(&peer->srcadr));
1968 return;
1969 }
1970
1971 /*
1972 * If the transmit timestamp duplicates our previous one, the
1973 * packet is a replay. This prevents the bad guys from replaying
1974 * the most recent packet, authenticated or not.
1975 */
1976 } else if ( ((FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->nonce, &p_xmt))
1977 || (!(FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->xmt, &p_xmt))
1978 ) {
1979 DPRINTF(2, ("receive: drop: Duplicate xmit\n"));
1980 peer->flash |= TEST1; /* duplicate */
1981 peer->oldpkt++;
1982 return;
1983
1984 /*
1985 * If this is a broadcast mode packet, make sure hisstratum
1986 * is appropriate. Don't do anything else here - we wait to
1987 * see if this is an interleave broadcast packet until after
1988 * we've validated the MAC that SHOULD be provided.
1989 *
1990 * hisstratum cannot be 0 - see assertion above.
1991 * If hisstratum is 15, then we'll advertise as UNSPEC but
1992 * at least we'll be able to sync with the broadcast server.
1993 */
1994 } else if (hismode == MODE_BROADCAST) {
1995 /* 0 is unexpected too, and impossible */
1996 if (STRATUM_UNSPEC <= hisstratum) {
1997 /* Is this a ++sys_declined or ??? */
1998 msyslog(LOG_INFO,
1999 "receive: Unexpected stratum (%d) in broadcast from %s",
2000 hisstratum, ntoa(&peer->srcadr));
2001 return;
2002 }
2003
2004 /*
2005 * Basic KoD validation checking:
2006 *
2007 * KoD packets are a mixed-blessing. Forged KoD packets
2008 * are DoS attacks. There are rare situations where we might
2009 * get a valid KoD response, though. Since KoD packets are
2010 * a special case that complicate the checks we do next, we
2011 * handle the basic KoD checks here.
2012 *
2013 * Note that we expect the incoming KoD packet to have its
2014 * (nonzero) org, rec, and xmt timestamps set to the xmt timestamp
2015 * that we have previously sent out. Watch interleave mode.
2016 */
2017 } else if (kissCode != NOKISS) {
2018 DEBUG_INSIST(!L_ISZERO(&p_xmt));
2019 if ( L_ISZERO(&p_org) /* We checked p_xmt above */
2020 || L_ISZERO(&p_rec)) {
2021 peer->bogusorg++;
2022 msyslog(LOG_INFO,
2023 "receive: KoD packet from %s has a zero org or rec timestamp. Ignoring.",
2024 ntoa(&peer->srcadr));
2025 return;
2026 }
2027
2028 if ( !L_ISEQU(&p_xmt, &p_org)
2029 || !L_ISEQU(&p_xmt, &p_rec)) {
2030 peer->bogusorg++;
2031 msyslog(LOG_INFO,
2032 "receive: KoD packet from %s has inconsistent xmt/org/rec timestamps. Ignoring.",
2033 ntoa(&peer->srcadr));
2034 return;
2035 }
2036
2037 /* Be conservative */
2038 if (peer->flip == 0 && !L_ISEQU(&p_org, &peer->aorg)) {
2039 peer->bogusorg++;
2040 msyslog(LOG_INFO,
2041 "receive: flip 0 KoD origin timestamp 0x%x.%08x from %s does not match 0x%x.%08x - ignoring.",
2042 p_org.l_ui, p_org.l_uf,
2043 ntoa(&peer->srcadr),
2044 peer->aorg.l_ui, peer->aorg.l_uf);
2045 return;
2046 } else if (peer->flip == 1 && !L_ISEQU(&p_org, &peer->borg)) {
2047 peer->bogusorg++;
2048 msyslog(LOG_INFO,
2049 "receive: flip 1 KoD origin timestamp 0x%x.%08x from %s does not match interleave 0x%x.%08x - ignoring.",
2050 p_org.l_ui, p_org.l_uf,
2051 ntoa(&peer->srcadr),
2052 peer->borg.l_ui, peer->borg.l_uf);
2053 return;
2054 }
2055
2056 /*
2057 * Basic mode checks:
2058 *
2059 * If there is no origin timestamp, it's either an initial
2060 * packet or we've already received a response to our query.
2061 * Of course, should 'aorg' be all-zero because this really
2062 * was the original transmit timestamp, we'll ignore this
2063 * reply. There is a window of one nanosecond once every
2064 * 136 years' time where this is possible. We currently
2065 * ignore this situation, as a completely zero timestamp
2066 * is (quietly?) disallowed.
2067 *
2068 * Otherwise, check for bogus packet in basic mode.
2069 * If it is bogus, switch to interleaved mode and
2070 * resynchronize, but only after confirming the packet is
2071 * not bogus in symmetric interleaved mode.
2072 *
2073 * This could also mean somebody is forging packets claiming
2074 * to be from us, attempting to cause our server to KoD us.
2075 *
2076 * We have earlier asserted that hisstratum cannot be 0.
2077 * If hisstratum is STRATUM_UNSPEC, it means he's not sync'd.
2078 */
2079
2080 /* XXX: FLAG_LOOPNONCE */
2081 DEBUG_INSIST(0 == (FLAG_LOOPNONCE & peer->flags));
2082
2083 if (RATEKISS == kissCode) {
2084 msyslog(LOG_INFO, "RATE KoD from %s poll %u",
2085 ntoa(&peer->srcadr), 1u << pkt->ppoll);
2086 } else {
2087 msyslog(LOG_INFO, "KoD %s from %s",
2088 refid_str(pkt->refid, -1),
2089 ntoa(&peer->srcadr));
2090 }
2091 } else if (peer->flip == 0) {
2092 if (0) {
2093 } else if (L_ISZERO(&p_org)) {
2094 const char *action;
2095
2096 #ifdef BUG3361
2097 msyslog(LOG_INFO,
2098 "receive: BUG 3361: Clearing peer->aorg ");
2099 L_CLR(&peer->aorg);
2100 /* Clear peer->nonce, too? */
2101 #endif
2102 /**/
2103 switch (hismode) {
2104 /* We allow 0org for: */
2105 case UCHAR_MAX:
2106 action = "Allow";
2107 break;
2108 /* We disallow 0org for: */
2109 case MODE_UNSPEC:
2110 case MODE_ACTIVE:
2111 case MODE_PASSIVE:
2112 case MODE_CLIENT:
2113 case MODE_SERVER:
2114 case MODE_BROADCAST:
2115 action = "Drop";
2116 peer->bogusorg++;
2117 peer->flash |= TEST2; /* bogus */
2118 break;
2119 default:
2120 action = ""; /* for cranky compilers / MSVC */
2121 INSIST(!"receive(): impossible hismode");
2122 break;
2123 }
2124 /**/
2125 msyslog(LOG_INFO,
2126 "receive: %s 0 origin timestamp from %s@%s xmt 0x%x.%08x",
2127 action, hm_str, ntoa(&peer->srcadr),
2128 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf));
2129 } else if ( L_ISZERO(&peer->aorg) && MODE_CLIENT != hismode
2130 && !memcmp("STEP", &peer->refid, 4)) {
2131 /* response came in just after we stepped clock, normal */
2132 } else if (!L_ISEQU(&p_org, &peer->aorg)) {
2133 /* are there cases here where we should bail? */
2134 /* Should we set TEST2 if we decide to try xleave? */
2135 peer->bogusorg++;
2136 peer->flash |= TEST2; /* bogus */
2137 msyslog(LOG_INFO,
2138 "duplicate or replay: org 0x%x.%08x does not match 0x%x.%08x from %s@%s",
2139 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf),
2140 peer->aorg.l_ui, peer->aorg.l_uf,
2141 hm_str, ntoa(&peer->srcadr));
2142 if ( !L_ISZERO(&peer->dst)
2143 && L_ISEQU(&p_org, &peer->dst)) {
2144 /* Might be the start of an interleave */
2145 if (dynamic_interleave) {
2146 peer->flip = 1;
2147 report_event(PEVNT_XLEAVE, peer, NULL);
2148 } else {
2149 msyslog(LOG_INFO,
2150 "receive: Dynamic interleave from %s@%s denied",
2151 hm_str, ntoa(&peer->srcadr));
2152 }
2153 }
2154 } else {
2155 L_CLR(&peer->aorg);
2156 /* XXX: FLAG_LOOPNONCE */
2157 }
2158
2159 /*
2160 * Check for valid nonzero timestamp fields.
2161 */
2162 } else if ( L_ISZERO(&p_org)
2163 || L_ISZERO(&p_rec)
2164 || L_ISZERO(&peer->dst)) {
2165 peer->flash |= TEST3; /* unsynch */
2166
2167 /*
2168 * Check for bogus packet in interleaved symmetric mode. This
2169 * can happen if a packet is lost, duplicated or crossed. If
2170 * found, flip and resynchronize.
2171 */
2172 } else if ( !L_ISZERO(&peer->dst)
2173 && !L_ISEQU(&p_org, &peer->dst)) {
2174 DPRINTF(2, ("receive: drop: Bogus packet in interleaved symmetric mode\n"));
2175 peer->bogusorg++;
2176 peer->flags |= FLAG_XBOGUS;
2177 peer->flash |= TEST2; /* bogus */
2178 #ifdef BUG3453
2179 return; /* Bogus packet, we are done */
2180 #endif
2181 }
2182
2183 /**/
2184
2185 /*
2186 * If this is a crypto_NAK, the server cannot authenticate a
2187 * client packet. The server might have just changed keys. Clear
2188 * the association and restart the protocol.
2189 */
2190 if (crypto_nak_test == VALIDNAK) {
2191 report_event(PEVNT_AUTH, peer, "crypto_NAK");
2192 peer->flash |= TEST5; /* bad auth */
2193 peer->badauth++;
2194 if (peer->flags & FLAG_PREEMPT) {
2195 if (unpeer_crypto_nak_early) {
2196 unpeer(peer);
2197 }
2198 DPRINTF(2, ("receive: drop: PREEMPT crypto_NAK\n"));
2199 return;
2200 }
2201 #ifdef AUTOKEY
2202 if (peer->crypto) {
2203 peer_clear(peer, "AUTH");
2204 }
2205 #endif /* AUTOKEY */
2206 DPRINTF(2, ("receive: drop: crypto_NAK\n"));
2207 return;
2208
2209 /*
2210 * If the digest fails or it's missing for authenticated
2211 * associations, the client cannot authenticate a server
2212 * reply to a client packet previously sent. The loopback check
2213 * is designed to avoid a bait-and-switch attack, which was
2214 * possible in past versions. If symmetric modes, return a
2215 * crypto-NAK. The peer should restart the protocol.
2216 */
2217 } else if (!AUTH(peer->keyid || has_mac ||
2218 (restrict_mask & RES_DONTTRUST), is_authentic)) {
2219
2220 if (peer->flash & PKT_TEST_MASK) {
2221 msyslog(LOG_INFO,
2222 "receive: Bad auth in packet with bad timestamps from %s denied - spoof?",
2223 ntoa(&peer->srcadr));
2224 return;
2225 }
2226
2227 report_event(PEVNT_AUTH, peer, "digest");
2228 peer->flash |= TEST5; /* bad auth */
2229 peer->badauth++;
2230 if ( has_mac
2231 && ( hismode == MODE_ACTIVE
2232 || hismode == MODE_PASSIVE))
2233 fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask);
2234 if (peer->flags & FLAG_PREEMPT) {
2235 if (unpeer_digest_early) {
2236 unpeer(peer);
2237 }
2238 }
2239 #ifdef AUTOKEY
2240 else if (peer_clear_digest_early && peer->crypto) {
2241 peer_clear(peer, "AUTH");
2242 }
2243 #endif /* AUTOKEY */
2244 DPRINTF(2, ("receive: drop: Bad or missing AUTH\n"));
2245 return;
2246 }
2247
2248 /*
2249 * For broadcast packets:
2250 *
2251 * HMS: This next line never made much sense to me, even
2252 * when it was up higher:
2253 * If an initial volley, bail out now and let the
2254 * client do its stuff.
2255 *
2256 * If the packet has not failed authentication, then
2257 * - if the origin timestamp is nonzero this is an
2258 * interleaved broadcast, so restart the protocol.
2259 * - else, this is not an interleaved broadcast packet.
2260 */
2261 if (hismode == MODE_BROADCAST) {
2262 if ( is_authentic == AUTH_OK
2263 || is_authentic == AUTH_NONE) {
2264 if (!L_ISZERO(&p_org)) {
2265 if (!(peer->flags & FLAG_XB)) {
2266 msyslog(LOG_INFO,
2267 "receive: Broadcast server at %s is in interleave mode",
2268 ntoa(&peer->srcadr));
2269 peer->flags |= FLAG_XB;
2270 peer->aorg = p_xmt;
2271 peer->borg = rbufp->recv_time;
2272 report_event(PEVNT_XLEAVE, peer, NULL);
2273 return;
2274 }
2275 } else if (peer->flags & FLAG_XB) {
2276 msyslog(LOG_INFO,
2277 "receive: Broadcast server at %s is no longer in interleave mode",
2278 ntoa(&peer->srcadr));
2279 peer->flags &= ~FLAG_XB;
2280 }
2281 } else {
2282 msyslog(LOG_INFO,
2283 "receive: Bad broadcast auth (%d) from %s",
2284 is_authentic, ntoa(&peer->srcadr));
2285 }
2286
2287 /*
2288 * Now that we know the packet is correctly authenticated,
2289 * update peer->bxmt.
2290 */
2291 peer->bxmt = p_xmt;
2292 }
2293
2294
2295 /*
2296 ** Update the state variables.
2297 */
2298 if (peer->flip == 0) {
2299 if (hismode != MODE_BROADCAST)
2300 peer->rec = p_xmt;
2301 peer->dst = rbufp->recv_time;
2302 }
2303 peer->xmt = p_xmt;
2304
2305 /*
2306 * Set the peer ppoll to the maximum of the packet ppoll and the
2307 * peer minpoll. If a kiss-o'-death, set the peer minpoll to
2308 * this maximum and advance the headway to give the sender some
2309 * headroom. Very intricate.
2310 */
2311
2312 /*
2313 * Check for any kiss codes. Note this is only used when a server
2314 * responds to a packet request.
2315 */
2316
2317 /*
2318 * Check to see if this is a RATE Kiss Code
2319 * Currently this kiss code will accept whatever valid poll
2320 * rate that the server sends
2321 */
2322 if ( (NTP_MINPOLL > pkt->ppoll)
2323 || (NTP_MAXPOLL < pkt->ppoll)
2324 ) {
2325 DPRINTF(2, ("RATEKISS: Invalid ppoll (%d) from %s\n",
2326 pkt->ppoll, stoa(&rbufp->recv_srcadr)));
2327 sys_badlength++;
2328 return; /* invalid packet poll */
2329 }
2330 peer->ppoll = max(peer->minpoll, pkt->ppoll);
2331 if (kissCode == RATEKISS) {
2332 peer->selbroken++; /* Increment the KoD count */
2333 report_event(PEVNT_RATE, peer, NULL);
2334 if (pkt->ppoll > peer->minpoll)
2335 peer->minpoll = peer->ppoll;
2336 peer->burst = peer->retry = 0;
2337 peer->throttle = (NTP_SHIFT + 1) * (1 << peer->minpoll);
2338 poll_update(peer, pkt->ppoll, 0);
2339 return; /* kiss-o'-death */
2340 }
2341 if (kissCode != NOKISS) {
2342 peer->selbroken++; /* Increment the KoD count */
2343 return; /* Drop any other kiss code packets */
2344 }
2345
2346
2347 /*
2348 * XXX
2349 */
2350
2351
2352 /*
2353 * If:
2354 * - this is a *cast (uni-, broad-, or m-) server packet
2355 * - and it's symmetric-key authenticated
2356 * then see if the sender's IP is trusted for this keyid.
2357 * If it is, great - nothing special to do here.
2358 * Otherwise, we should report and bail.
2359 *
2360 * Autokey-authenticated packets are accepted.
2361 */
2362
2363 switch (hismode) {
2364 case MODE_SERVER: /* server mode */
2365 case MODE_BROADCAST: /* broadcast mode */
2366 case MODE_ACTIVE: /* symmetric active mode */
2367 case MODE_PASSIVE: /* symmetric passive mode */
2368 if ( is_authentic == AUTH_OK
2369 && skeyid
2370 && skeyid <= NTP_MAXKEY
2371 && !authistrustedip(skeyid, &peer->srcadr)) {
2372 report_event(PEVNT_AUTH, peer, "authIP");
2373 peer->badauth++;
2374 return;
2375 }
2376 break;
2377
2378 case MODE_CLIENT: /* client mode */
2379 #if 0 /* At this point, MODE_CONTROL is overloaded by MODE_BCLIENT */
2380 case MODE_CONTROL: /* control mode */
2381 #endif
2382 case MODE_PRIVATE: /* private mode */
2383 case MODE_BCLIENT: /* broadcast client mode */
2384 break;
2385
2386 case MODE_UNSPEC: /* unspecified (old version) */
2387 default:
2388 msyslog(LOG_INFO,
2389 "receive: Unexpected mode (%d) in packet from %s",
2390 hismode, ntoa(&peer->srcadr));
2391 break;
2392 }
2393
2394
2395 /*
2396 * That was hard and I am sweaty, but the packet is squeaky
2397 * clean. Get on with real work.
2398 */
2399 peer->timereceived = current_time;
2400 peer->timelastrec = current_time;
2401 if (is_authentic == AUTH_OK)
2402 peer->flags |= FLAG_AUTHENTIC;
2403 else
2404 peer->flags &= ~FLAG_AUTHENTIC;
2405
2406 #ifdef AUTOKEY
2407 /*
2408 * More autokey dance. The rules of the cha-cha are as follows:
2409 *
2410 * 1. If there is no key or the key is not auto, do nothing.
2411 *
2412 * 2. If this packet is in response to the one just previously
2413 * sent or from a broadcast server, do the extension fields.
2414 * Otherwise, assume bogosity and bail out.
2415 *
2416 * 3. If an extension field contains a verified signature, it is
2417 * self-authenticated and we sit the dance.
2418 *
2419 * 4. If this is a server reply, check only to see that the
2420 * transmitted key ID matches the received key ID.
2421 *
2422 * 5. Check to see that one or more hashes of the current key ID
2423 * matches the previous key ID or ultimate original key ID
2424 * obtained from the broadcaster or symmetric peer. If no
2425 * match, sit the dance and call for new autokey values.
2426 *
2427 * In case of crypto error, fire the orchestra, stop dancing and
2428 * restart the protocol.
2429 */
2430 if (peer->flags & FLAG_SKEY) {
2431 /*
2432 * Decrement remaining autokey hashes. This isn't
2433 * perfect if a packet is lost, but results in no harm.
2434 */
2435 ap = (struct autokey *)peer->recval.ptr;
2436 if (ap != NULL) {
2437 if (ap->seq > 0)
2438 ap->seq--;
2439 }
2440 peer->flash |= TEST8;
2441 rval = crypto_recv(peer, rbufp);
2442 if (rval == XEVNT_OK) {
2443 peer->unreach = 0;
2444 } else {
2445 if (rval == XEVNT_ERR) {
2446 report_event(PEVNT_RESTART, peer,
2447 "crypto error");
2448 peer_clear(peer, "CRYP");
2449 peer->flash |= TEST9; /* bad crypt */
2450 if (peer->flags & FLAG_PREEMPT) {
2451 if (unpeer_crypto_early) {
2452 unpeer(peer);
2453 }
2454 }
2455 }
2456 return;
2457 }
2458
2459 /*
2460 * If server mode, verify the receive key ID matches
2461 * the transmit key ID.
2462 */
2463 if (hismode == MODE_SERVER) {
2464 if (skeyid == peer->keyid)
2465 peer->flash &= ~TEST8;
2466
2467 /*
2468 * If an extension field is present, verify only that it
2469 * has been correctly signed. We don't need a sequence
2470 * check here, but the sequence continues.
2471 */
2472 } else if (!(peer->flash & TEST8)) {
2473 peer->pkeyid = skeyid;
2474
2475 /*
2476 * Now the fun part. Here, skeyid is the current ID in
2477 * the packet, pkeyid is the ID in the last packet and
2478 * tkeyid is the hash of skeyid. If the autokey values
2479 * have not been received, this is an automatic error.
2480 * If so, check that the tkeyid matches pkeyid. If not,
2481 * hash tkeyid and try again. If the number of hashes
2482 * exceeds the number remaining in the sequence, declare
2483 * a successful failure and refresh the autokey values.
2484 */
2485 } else if (ap != NULL) {
2486 int i;
2487
2488 for (i = 0; ; i++) {
2489 if ( tkeyid == peer->pkeyid
2490 || tkeyid == ap->key) {
2491 peer->flash &= ~TEST8;
2492 peer->pkeyid = skeyid;
2493 ap->seq -= i;
2494 break;
2495 }
2496 if (i > ap->seq) {
2497 peer->crypto &=
2498 ~CRYPTO_FLAG_AUTO;
2499 break;
2500 }
2501 tkeyid = session_key(
2502 &rbufp->recv_srcadr, dstadr_sin,
2503 tkeyid, pkeyid, 0);
2504 }
2505 if (peer->flash & TEST8)
2506 report_event(PEVNT_AUTH, peer, "keylist");
2507 }
2508 if (!(peer->crypto & CRYPTO_FLAG_PROV)) /* test 9 */
2509 peer->flash |= TEST8; /* bad autokey */
2510
2511 /*
2512 * The maximum lifetime of the protocol is about one
2513 * week before restarting the Autokey protocol to
2514 * refresh certificates and leapseconds values.
2515 */
2516 if (current_time > peer->refresh) {
2517 report_event(PEVNT_RESTART, peer,
2518 "crypto refresh");
2519 peer_clear(peer, "TIME");
2520 return;
2521 }
2522 }
2523 #endif /* AUTOKEY */
2524
2525 /*
2526 * The dance is complete and the flash bits have been lit. Toss
2527 * the packet over the fence for processing, which may light up
2528 * more flashers. Leave if the packet is not good.
2529 */
2530 process_packet(peer, pkt, rbufp->recv_length);
2531 /* Bug 2734: TEST3 prevents initial interleave sync */
2532 if ((~TEST3 & peer->flash) & PKT_TEST_MASK) {
2533 return;
2534 }
2535
2536 /* [bug 3592] Update poll. Ideally this should not happen in a
2537 * receive branch, but too much is going on here... at least we
2538 * do it only if the packet was good!
2539 */
2540 poll_update(peer, peer->hpoll, (peer->hmode == MODE_CLIENT));
2541
2542 /*
2543 * In interleaved mode update the state variables. Also adjust the
2544 * transmit phase to avoid crossover.
2545 */
2546 if (peer->flip != 0) {
2547 peer->rec = p_rec;
2548 peer->dst = rbufp->recv_time;
2549 if (peer->nextdate - current_time < (1U << min(peer->ppoll,
2550 peer->hpoll)) / 2)
2551 peer->nextdate++;
2552 else
2553 peer->nextdate--;
2554 }
2555 }
2556
2557
2558 /*
2559 * process_packet - Packet Procedure, a la Section 3.4.4 of RFC-1305
2560 * Or almost, at least. If we're in here we have a reasonable
2561 * expectation that we will be having a long term
2562 * relationship with this host.
2563 */
2564 void
process_packet(register struct peer * peer,register struct pkt * pkt,u_int len)2565 process_packet(
2566 register struct peer *peer,
2567 register struct pkt *pkt,
2568 u_int len
2569 )
2570 {
2571 double t34, t21;
2572 double p_offset, p_del, p_disp;
2573 l_fp p_rec, p_xmt, p_org, p_reftime, ci;
2574 u_char pmode, pleap, pversion, pstratum;
2575 #ifdef ASSYM
2576 int itemp;
2577 double etemp, ftemp, td;
2578 #endif /* ASSYM */
2579
2580 p_del = FPTOD(NTOHS_FP(pkt->rootdelay));
2581 p_offset = 0;
2582 p_disp = FPTOD(NTOHS_FP(pkt->rootdisp));
2583 NTOHL_FP(&pkt->reftime, &p_reftime);
2584 NTOHL_FP(&pkt->org, &p_org);
2585 NTOHL_FP(&pkt->rec, &p_rec);
2586 NTOHL_FP(&pkt->xmt, &p_xmt);
2587 pmode = PKT_MODE(pkt->li_vn_mode);
2588 pleap = PKT_LEAP(pkt->li_vn_mode);
2589 pversion = PKT_VERSION(pkt->li_vn_mode);
2590 pstratum = PKT_TO_STRATUM(pkt->stratum);
2591
2592 /*
2593 * Verify the server is synchronized; that is, the leap bits,
2594 * stratum and root distance are valid.
2595 */
2596 if ( pleap == LEAP_NOTINSYNC /* test 6 */
2597 || pstratum < sys_floor || pstratum >= sys_ceiling)
2598 peer->flash |= TEST6; /* bad synch or strat */
2599 if (p_del / 2 + p_disp >= MAXDISPERSE) /* test 7 */
2600 peer->flash |= TEST7; /* bad header */
2601
2602 /*
2603 * If any tests fail at this point, the packet is discarded.
2604 * Note that some flashers may have already been set in the
2605 * receive() routine.
2606 */
2607 if (peer->flash & PKT_TEST_MASK) {
2608 peer->seldisptoolarge++;
2609 DPRINTF(1, ("packet: flash header %04x\n",
2610 peer->flash));
2611 /* [Bug 3592] do *not* update poll on bad packets! */
2612 return;
2613 }
2614
2615 /*
2616 * update stats, now that we really handle this packet:
2617 */
2618 sys_processed++;
2619 peer->processed++;
2620
2621 /*
2622 * Capture the header values in the client/peer association..
2623 */
2624 record_raw_stats(&peer->srcadr,
2625 peer->dstadr ? &peer->dstadr->sin : NULL,
2626 &p_org, &p_rec, &p_xmt, &peer->dst,
2627 pleap, pversion, pmode, pstratum, pkt->ppoll, pkt->precision,
2628 p_del, p_disp, pkt->refid,
2629 len - MIN_V4_PKT_LEN, (u_char *)&pkt->exten);
2630 peer->leap = pleap;
2631 peer->stratum = min(pstratum, STRATUM_UNSPEC);
2632 peer->pmode = pmode;
2633 peer->precision = pkt->precision;
2634 peer->rootdelay = p_del;
2635 peer->rootdisp = p_disp;
2636 peer->refid = pkt->refid; /* network byte order */
2637 peer->reftime = p_reftime;
2638
2639 /*
2640 * First, if either burst mode is armed, enable the burst.
2641 * Compute the headway for the next packet and delay if
2642 * necessary to avoid exceeding the threshold.
2643 */
2644 if (peer->retry > 0) {
2645 peer->retry = 0;
2646 if (peer->reach)
2647 peer->burst = min(1 << (peer->hpoll -
2648 peer->minpoll), NTP_SHIFT) - 1;
2649 else
2650 peer->burst = NTP_IBURST - 1;
2651 if (peer->burst > 0)
2652 peer->nextdate = current_time;
2653 }
2654
2655 /*
2656 * If the peer was previously unreachable, raise a trap. In any
2657 * case, mark it reachable.
2658 */
2659 if (!peer->reach) {
2660 report_event(PEVNT_REACH, peer, NULL);
2661 peer->timereachable = current_time;
2662 }
2663 peer->reach |= 1;
2664
2665 /*
2666 * For a client/server association, calculate the clock offset,
2667 * roundtrip delay and dispersion. The equations are reordered
2668 * from the spec for more efficient use of temporaries. For a
2669 * broadcast association, offset the last measurement by the
2670 * computed delay during the client/server volley. Note the
2671 * computation of dispersion includes the system precision plus
2672 * that due to the frequency error since the origin time.
2673 *
2674 * It is very important to respect the hazards of overflow. The
2675 * only permitted operation on raw timestamps is subtraction,
2676 * where the result is a signed quantity spanning from 68 years
2677 * in the past to 68 years in the future. To avoid loss of
2678 * precision, these calculations are done using 64-bit integer
2679 * arithmetic. However, the offset and delay calculations are
2680 * sums and differences of these first-order differences, which
2681 * if done using 64-bit integer arithmetic, would be valid over
2682 * only half that span. Since the typical first-order
2683 * differences are usually very small, they are converted to 64-
2684 * bit doubles and all remaining calculations done in floating-
2685 * double arithmetic. This preserves the accuracy while
2686 * retaining the 68-year span.
2687 *
2688 * There are three interleaving schemes, basic, interleaved
2689 * symmetric and interleaved broadcast. The timestamps are
2690 * idioscyncratically different. See the onwire briefing/white
2691 * paper at www.eecis.udel.edu/~mills for details.
2692 *
2693 * Interleaved symmetric mode
2694 * t1 = peer->aorg/borg, t2 = peer->rec, t3 = p_xmt,
2695 * t4 = peer->dst
2696 */
2697 if (peer->flip != 0) {
2698 ci = p_xmt; /* t3 - t4 */
2699 L_SUB(&ci, &peer->dst);
2700 LFPTOD(&ci, t34);
2701 ci = p_rec; /* t2 - t1 */
2702 if (peer->flip > 0)
2703 L_SUB(&ci, &peer->borg);
2704 else
2705 L_SUB(&ci, &peer->aorg);
2706 LFPTOD(&ci, t21);
2707 p_del = t21 - t34;
2708 p_offset = (t21 + t34) / 2.;
2709 if (p_del < 0 || p_del > 1.) {
2710 mprintf_event(PEVNT_XERR, peer,
2711 "t21 %.9f t34 %.9f", t21, t34);
2712 return;
2713 }
2714
2715 /*
2716 * Broadcast modes
2717 */
2718 } else if (peer->pmode == MODE_BROADCAST) {
2719
2720 /*
2721 * Interleaved broadcast mode. Use interleaved timestamps.
2722 * t1 = peer->borg, t2 = p_org, t3 = p_org, t4 = aorg
2723 */
2724 if (peer->flags & FLAG_XB) {
2725 ci = p_org; /* delay */
2726 L_SUB(&ci, &peer->aorg);
2727 LFPTOD(&ci, t34);
2728 ci = p_org; /* t2 - t1 */
2729 L_SUB(&ci, &peer->borg);
2730 LFPTOD(&ci, t21);
2731 peer->aorg = p_xmt;
2732 peer->borg = peer->dst;
2733 if (t34 < 0 || t34 > 1.) {
2734 /* drop all if in the initial volley */
2735 if (FLAG_BC_VOL & peer->flags)
2736 goto bcc_init_volley_fail;
2737 mprintf_event(PEVNT_XERR, peer,
2738 "offset %.9f delay %.9f",
2739 t21, t34);
2740 return;
2741 }
2742 p_offset = t21;
2743 peer->xleave = t34;
2744
2745 /*
2746 * Basic broadcast - use direct timestamps.
2747 * t3 = p_xmt, t4 = peer->dst
2748 */
2749 } else {
2750 ci = p_xmt; /* t3 - t4 */
2751 L_SUB(&ci, &peer->dst);
2752 LFPTOD(&ci, t34);
2753 p_offset = t34;
2754 }
2755
2756 /*
2757 * When calibration is complete and the clock is
2758 * synchronized, the bias is calculated as the difference
2759 * between the unicast timestamp and the broadcast
2760 * timestamp. This works for both basic and interleaved
2761 * modes.
2762 * [Bug 3031] Don't keep this peer when the delay
2763 * calculation gives reason to suspect clock steps.
2764 * This is assumed for delays > 50ms.
2765 */
2766 if (FLAG_BC_VOL & peer->flags) {
2767 peer->flags &= ~FLAG_BC_VOL;
2768 peer->delay = fabs(peer->offset - p_offset) * 2;
2769 DPRINTF(2, ("broadcast volley: initial delay=%.6f\n",
2770 peer->delay));
2771 if (peer->delay > fabs(sys_bdelay)) {
2772 bcc_init_volley_fail:
2773 DPRINTF(2, ("%s", "broadcast volley: initial delay exceeds limit\n"));
2774 unpeer(peer);
2775 return;
2776 }
2777 }
2778 peer->nextdate = current_time + (1u << peer->ppoll) - 2u;
2779 p_del = peer->delay;
2780 p_offset += p_del / 2;
2781
2782
2783 /*
2784 * Basic mode, otherwise known as the old fashioned way.
2785 *
2786 * t1 = p_org, t2 = p_rec, t3 = p_xmt, t4 = peer->dst
2787 */
2788 } else {
2789 ci = p_xmt; /* t3 - t4 */
2790 L_SUB(&ci, &peer->dst);
2791 LFPTOD(&ci, t34);
2792 ci = p_rec; /* t2 - t1 */
2793 L_SUB(&ci, &p_org);
2794 LFPTOD(&ci, t21);
2795 p_del = fabs(t21 - t34);
2796 p_offset = (t21 + t34) / 2.;
2797 }
2798 p_del = max(p_del, LOGTOD(sys_precision));
2799 p_disp = LOGTOD(sys_precision) + LOGTOD(peer->precision) +
2800 clock_phi * p_del;
2801
2802 #if ASSYM
2803 /*
2804 * This code calculates the outbound and inbound data rates by
2805 * measuring the differences between timestamps at different
2806 * packet lengths. This is helpful in cases of large asymmetric
2807 * delays commonly experienced on deep space communication
2808 * links.
2809 */
2810 if (peer->t21_last > 0 && peer->t34_bytes > 0) {
2811 itemp = peer->t21_bytes - peer->t21_last;
2812 if (itemp > 25) {
2813 etemp = t21 - peer->t21;
2814 if (fabs(etemp) > 1e-6) {
2815 ftemp = itemp / etemp;
2816 if (ftemp > 1000.)
2817 peer->r21 = ftemp;
2818 }
2819 }
2820 itemp = len - peer->t34_bytes;
2821 if (itemp > 25) {
2822 etemp = -t34 - peer->t34;
2823 if (fabs(etemp) > 1e-6) {
2824 ftemp = itemp / etemp;
2825 if (ftemp > 1000.)
2826 peer->r34 = ftemp;
2827 }
2828 }
2829 }
2830
2831 /*
2832 * The following section compensates for different data rates on
2833 * the outbound (d21) and inbound (t34) directions. To do this,
2834 * it finds t such that r21 * t - r34 * (d - t) = 0, where d is
2835 * the roundtrip delay. Then it calculates the correction as a
2836 * fraction of d.
2837 */
2838 peer->t21 = t21;
2839 peer->t21_last = peer->t21_bytes;
2840 peer->t34 = -t34;
2841 peer->t34_bytes = len;
2842 DPRINTF(2, ("packet: t21 %.9lf %d t34 %.9lf %d\n", peer->t21,
2843 peer->t21_bytes, peer->t34, peer->t34_bytes));
2844 if (peer->r21 > 0 && peer->r34 > 0 && p_del > 0) {
2845 if (peer->pmode != MODE_BROADCAST)
2846 td = (peer->r34 / (peer->r21 + peer->r34) -
2847 .5) * p_del;
2848 else
2849 td = 0;
2850
2851 /*
2852 * Unfortunately, in many cases the errors are
2853 * unacceptable, so for the present the rates are not
2854 * used. In future, we might find conditions where the
2855 * calculations are useful, so this should be considered
2856 * a work in progress.
2857 */
2858 t21 -= td;
2859 t34 -= td;
2860 DPRINTF(2, ("packet: del %.6lf r21 %.1lf r34 %.1lf %.6lf\n",
2861 p_del, peer->r21 / 1e3, peer->r34 / 1e3,
2862 td));
2863 }
2864 #endif /* ASSYM */
2865
2866 /*
2867 * That was awesome. Now hand off to the clock filter.
2868 */
2869 clock_filter(peer, p_offset + peer->bias, p_del, p_disp);
2870
2871 /*
2872 * If we are in broadcast calibrate mode, return to broadcast
2873 * client mode when the client is fit and the autokey dance is
2874 * complete.
2875 */
2876 if ( (FLAG_BC_VOL & peer->flags)
2877 && MODE_CLIENT == peer->hmode
2878 && !(TEST11 & peer_unfit(peer))) { /* distance exceeded */
2879 #ifdef AUTOKEY
2880 if (peer->flags & FLAG_SKEY) {
2881 if (!(~peer->crypto & CRYPTO_FLAG_ALL))
2882 peer->hmode = MODE_BCLIENT;
2883 } else {
2884 peer->hmode = MODE_BCLIENT;
2885 }
2886 #else /* !AUTOKEY follows */
2887 peer->hmode = MODE_BCLIENT;
2888 #endif /* !AUTOKEY */
2889 }
2890 }
2891
2892
2893 /*
2894 * clock_update - Called at system process update intervals.
2895 */
2896 static void
clock_update(struct peer * peer)2897 clock_update(
2898 struct peer *peer /* peer structure pointer */
2899 )
2900 {
2901 double dtemp;
2902 l_fp now;
2903 #ifdef HAVE_LIBSCF_H
2904 char *fmri;
2905 #endif /* HAVE_LIBSCF_H */
2906
2907 /*
2908 * Update the system state variables. We do this very carefully,
2909 * as the poll interval might need to be clamped differently.
2910 */
2911 sys_peer = peer;
2912 sys_epoch = peer->epoch;
2913 if (sys_poll < peer->minpoll)
2914 sys_poll = peer->minpoll;
2915 if (sys_poll > peer->maxpoll)
2916 sys_poll = peer->maxpoll;
2917 poll_update(peer, sys_poll, 0);
2918 sys_stratum = min(peer->stratum + 1, STRATUM_UNSPEC);
2919 if ( peer->stratum == STRATUM_REFCLOCK
2920 || peer->stratum == STRATUM_UNSPEC)
2921 sys_refid = peer->refid;
2922 else
2923 sys_refid = addr2refid(&peer->srcadr);
2924 /*
2925 * Root Dispersion (E) is defined (in RFC 5905) as:
2926 *
2927 * E = p.epsilon_r + p.epsilon + p.psi + PHI*(s.t - p.t) + |THETA|
2928 *
2929 * where:
2930 * p.epsilon_r is the PollProc's root dispersion
2931 * p.epsilon is the PollProc's dispersion
2932 * p.psi is the PollProc's jitter
2933 * THETA is the combined offset
2934 *
2935 * NB: Think Hard about where these numbers come from and
2936 * what they mean. When did peer->update happen? Has anything
2937 * interesting happened since then? What values are the most
2938 * defensible? Why?
2939 *
2940 * DLM thinks this equation is probably the best of all worse choices.
2941 */
2942 dtemp = peer->rootdisp
2943 + peer->disp
2944 + sys_jitter
2945 + clock_phi * (current_time - peer->update)
2946 + fabs(sys_offset);
2947
2948 p2_rootdisp = prev_rootdisp;
2949 prev_rootdisp = sys_rootdisp;
2950 if (dtemp > sys_mindisp)
2951 sys_rootdisp = dtemp;
2952 else
2953 sys_rootdisp = sys_mindisp;
2954
2955 sys_rootdelay = peer->delay + peer->rootdelay;
2956
2957 p2_reftime = prev_reftime;
2958 p2_time = prev_time;
2959
2960 prev_reftime = sys_reftime;
2961 prev_time = current_time + 64 + (rand() & 0x3f); /* 64-127 s */
2962
2963 sys_reftime = peer->dst;
2964
2965 DPRINTF(1, ("clock_update: at %lu sample %lu associd %d\n",
2966 current_time, peer->epoch, peer->associd));
2967
2968 /*
2969 * Comes now the moment of truth. Crank the clock discipline and
2970 * see what comes out.
2971 */
2972 switch (local_clock(peer, sys_offset)) {
2973
2974 /*
2975 * Clock exceeds panic threshold. Life as we know it ends.
2976 */
2977 case -1:
2978 msyslog(LOG_ERR, "Clock offset exceeds panic threshold.");
2979 #ifdef HAVE_LIBSCF_H
2980 /*
2981 * For Solaris enter the maintenance mode.
2982 */
2983 if ((fmri = getenv("SMF_FMRI")) != NULL) {
2984 if (smf_maintain_instance(fmri, 0) < 0) {
2985 msyslog(LOG_ERR, "smf_maintain_instance: %s",
2986 scf_strerror(scf_error()));
2987 exit(1);
2988 }
2989 /*
2990 * Sleep until SMF kills us.
2991 */
2992 msyslog(LOG_ERR, "%s placed into maintenance. "
2993 "Set system clock by hand before clearing.",
2994 fmri);
2995 for (;;)
2996 pause();
2997 }
2998 #endif /* HAVE_LIBSCF_H */
2999 msyslog(LOG_ERR, "Set system clock by hand.");
3000 exit (-1);
3001 /* not reached */
3002
3003 /*
3004 * Clock was stepped. Flush all time values of all peers.
3005 */
3006 case 2:
3007 clear_all();
3008 set_sys_leap(LEAP_NOTINSYNC);
3009 sys_stratum = STRATUM_UNSPEC;
3010 memcpy(&sys_refid, "STEP", 4);
3011 sys_rootdelay = 0;
3012 p2_rootdisp = 0;
3013 prev_rootdisp = 0;
3014 sys_rootdisp = 0;
3015 L_CLR(&p2_reftime); /* Should we clear p2_reftime? */
3016 L_CLR(&prev_reftime); /* Should we clear prev_reftime? */
3017 L_CLR(&sys_reftime);
3018 sys_jitter = LOGTOD(sys_precision);
3019 leapsec_reset_frame();
3020 break;
3021
3022 /*
3023 * Clock was slewed. Handle the leapsecond stuff.
3024 */
3025 case 1:
3026
3027 /*
3028 * If this is the first time the clock is set, reset the
3029 * leap bits. If crypto, the timer will goose the setup
3030 * process.
3031 */
3032 if (sys_leap == LEAP_NOTINSYNC) {
3033 set_sys_leap(LEAP_NOWARNING);
3034 #ifdef AUTOKEY
3035 if (crypto_flags)
3036 crypto_update();
3037 #endif /* AUTOKEY */
3038
3039 }
3040
3041 /*
3042 * If there is no leap second pending and the number of
3043 * survivor leap bits is greater than half the number of
3044 * survivors, try to schedule a leap for the end of the
3045 * current month. (This only works if no leap second for
3046 * that range is in the table, so doing this more than
3047 * once is mostly harmless.)
3048 */
3049 if (leapsec == LSPROX_NOWARN) {
3050 if ( leap_vote_ins > leap_vote_del
3051 && leap_vote_ins > sys_survivors / 2) {
3052 get_systime(&now);
3053 leapsec_add_dyn(TRUE, now.l_ui, NULL);
3054 }
3055 if ( leap_vote_del > leap_vote_ins
3056 && leap_vote_del > sys_survivors / 2) {
3057 get_systime(&now);
3058 leapsec_add_dyn(FALSE, now.l_ui, NULL);
3059 }
3060 }
3061 break;
3062
3063 /*
3064 * Popcorn spike or step threshold exceeded. Pretend it never
3065 * happened.
3066 */
3067 default:
3068 break;
3069 }
3070 }
3071
3072
3073 /*
3074 * poll_update - update peer poll interval
3075 */
3076 void
poll_update(struct peer * peer,u_char mpoll,u_char skewpoll)3077 poll_update(
3078 struct peer *peer, /* peer structure pointer */
3079 u_char mpoll,
3080 u_char skewpoll
3081 )
3082 {
3083 u_long next, utemp, limit;
3084 u_char hpoll;
3085
3086 /*
3087 * This routine figures out when the next poll should be sent.
3088 * That turns out to be wickedly complicated. One problem is
3089 * that sometimes the time for the next poll is in the past when
3090 * the poll interval is reduced. We watch out for races here
3091 * between the receive process and the poll process.
3092 *
3093 * Clamp the poll interval between minpoll and maxpoll.
3094 */
3095 hpoll = max(min(peer->maxpoll, mpoll), peer->minpoll);
3096
3097 #ifdef AUTOKEY
3098 /*
3099 * If during the crypto protocol the poll interval has changed,
3100 * the lifetimes in the key list are probably bogus. Purge the
3101 * the key list and regenerate it later.
3102 */
3103 if ((peer->flags & FLAG_SKEY) && hpoll != peer->hpoll)
3104 key_expire(peer);
3105 #endif /* AUTOKEY */
3106 peer->hpoll = hpoll;
3107
3108 /*
3109 * There are three variables important for poll scheduling, the
3110 * current time (current_time), next scheduled time (nextdate)
3111 * and the earliest time (utemp). The earliest time is 2 s
3112 * seconds, but could be more due to rate management. When
3113 * sending in a burst, use the earliest time. When not in a
3114 * burst but with a reply pending, send at the earliest time
3115 * unless the next scheduled time has not advanced. This can
3116 * only happen if multiple replies are pending in the same
3117 * response interval. Otherwise, send at the later of the next
3118 * scheduled time and the earliest time.
3119 *
3120 * Now we figure out if there is an override. If a burst is in
3121 * progress and we get called from the receive process, just
3122 * slink away. If called from the poll process, delay 1 s for a
3123 * reference clock, otherwise 2 s.
3124 */
3125 utemp = current_time + max(peer->throttle - (NTP_SHIFT - 1) *
3126 (1 << peer->minpoll), ntp_minpkt);
3127
3128 /*[Bug 3592] avoid unlimited postpone of next poll */
3129 limit = (2u << hpoll);
3130 if (limit > 64)
3131 limit -= (limit >> 2);
3132 limit += peer->outdate;
3133 if (limit < current_time)
3134 limit = current_time;
3135
3136 if (peer->burst > 0) {
3137 if (peer->nextdate > current_time)
3138 return;
3139 #ifdef REFCLOCK
3140 else if (peer->flags & FLAG_REFCLOCK)
3141 peer->nextdate = current_time + RESP_DELAY;
3142 #endif /* REFCLOCK */
3143 else
3144 peer->nextdate = utemp;
3145
3146 #ifdef AUTOKEY
3147 /*
3148 * If a burst is not in progress and a crypto response message
3149 * is pending, delay 2 s, but only if this is a new interval.
3150 */
3151 } else if (peer->cmmd != NULL) {
3152 if (peer->nextdate > current_time) {
3153 if (peer->nextdate + ntp_minpkt != utemp)
3154 peer->nextdate = utemp;
3155 } else {
3156 peer->nextdate = utemp;
3157 }
3158 #endif /* AUTOKEY */
3159
3160 /*
3161 * The ordinary case. If a retry, use minpoll; if unreachable,
3162 * use host poll; otherwise, use the minimum of host and peer
3163 * polls; In other words, oversampling is okay but
3164 * understampling is evil. Use the maximum of this value and the
3165 * headway. If the average headway is greater than the headway
3166 * threshold, increase the headway by the minimum interval.
3167 */
3168 } else {
3169 if (peer->retry > 0)
3170 hpoll = peer->minpoll;
3171 else
3172 hpoll = min(peer->ppoll, peer->hpoll);
3173 #ifdef REFCLOCK
3174 if (peer->flags & FLAG_REFCLOCK)
3175 next = 1 << hpoll;
3176 else
3177 #endif /* REFCLOCK */
3178 next = ((0x1000UL | (ntp_random() & 0x0ff)) <<
3179 hpoll) >> 12;
3180 next += peer->outdate;
3181 /* XXX: bug3596: Deal with poll skew list? */
3182 if (skewpoll) {
3183 psl_item psi;
3184
3185 if (0 == get_pollskew(hpoll, &psi)) {
3186 int sub = psi.sub;
3187 int qty = psi.qty;
3188 int msk = psi.msk;
3189 int val;
3190
3191 if ( 0 != sub
3192 || 0 != qty) {
3193 do {
3194 val = ntp_random() & msk;
3195 } while (val > qty);
3196
3197 next -= sub;
3198 next += val;
3199 }
3200 } else {
3201 /* get_pollskew() already logged this */
3202 }
3203 }
3204 if (next > utemp)
3205 peer->nextdate = next;
3206 else
3207 peer->nextdate = utemp;
3208 if (peer->throttle > (1 << peer->minpoll))
3209 peer->nextdate += ntp_minpkt;
3210 }
3211
3212 /*[Bug 3592] avoid unlimited postpone of next poll */
3213 if (peer->nextdate > limit) {
3214 DPRINTF(1, ("poll_update: clamp reached; limit %lu next %lu\n",
3215 limit, peer->nextdate));
3216 peer->nextdate = limit;
3217 }
3218 DPRINTF(2, ("poll_update: at %lu %s poll %d burst %d retry %d head %d early %lu next %lu\n",
3219 current_time, ntoa(&peer->srcadr), peer->hpoll,
3220 peer->burst, peer->retry, peer->throttle,
3221 utemp - current_time, peer->nextdate -
3222 current_time));
3223 }
3224
3225
3226 /*
3227 * peer_clear - clear peer filter registers. See Section 3.4.8 of the
3228 * spec.
3229 */
3230 void
peer_clear(struct peer * peer,const char * ident)3231 peer_clear(
3232 struct peer *peer, /* peer structure */
3233 const char *ident /* tally lights */
3234 )
3235 {
3236 static u_long earliest;
3237 u_char u;
3238 l_fp bxmt = peer->bxmt; /* bcast clients retain this! */
3239
3240 #ifdef AUTOKEY
3241 /*
3242 * If cryptographic credentials have been acquired, toss them to
3243 * Valhalla. Note that autokeys are ephemeral, in that they are
3244 * tossed immediately upon use. Therefore, the keylist can be
3245 * purged anytime without needing to preserve random keys. Note
3246 * that, if the peer is purged, the cryptographic variables are
3247 * purged, too. This makes it much harder to sneak in some
3248 * unauthenticated data in the clock filter.
3249 */
3250 key_expire(peer);
3251 if (peer->iffval != NULL)
3252 BN_free(peer->iffval);
3253 value_free(&peer->cookval);
3254 value_free(&peer->recval);
3255 value_free(&peer->encrypt);
3256 value_free(&peer->sndval);
3257 if (peer->cmmd != NULL)
3258 free(peer->cmmd);
3259 if (peer->subject != NULL)
3260 free(peer->subject);
3261 if (peer->issuer != NULL)
3262 free(peer->issuer);
3263 #endif /* AUTOKEY */
3264
3265 /*
3266 * Clear all values, including the optional crypto values above.
3267 */
3268 memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO(peer));
3269 peer->ppoll = peer->maxpoll;
3270 peer->hpoll = peer->minpoll;
3271 peer->disp = MAXDISPERSE;
3272 peer->flash = peer_unfit(peer);
3273 peer->jitter = LOGTOD(sys_precision);
3274
3275 /* Don't throw away our broadcast replay protection */
3276 if (peer->hmode == MODE_BCLIENT)
3277 peer->bxmt = bxmt;
3278
3279 /*
3280 * If interleave mode, initialize the alternate origin switch.
3281 */
3282 if (peer->flags & FLAG_XLEAVE)
3283 peer->flip = 1;
3284 for (u = 0; u < NTP_SHIFT; u++) {
3285 peer->filter_order[u] = u;
3286 peer->filter_disp[u] = MAXDISPERSE;
3287 }
3288 #ifdef REFCLOCK
3289 if (!(peer->flags & FLAG_REFCLOCK)) {
3290 #endif
3291 peer->leap = LEAP_NOTINSYNC;
3292 peer->stratum = STRATUM_UNSPEC;
3293 memcpy(&peer->refid, ident, 4);
3294 #ifdef REFCLOCK
3295 } else {
3296 /* Clear refclock sample filter */
3297 peer->procptr->codeproc = 0;
3298 peer->procptr->coderecv = 0;
3299 }
3300 #endif
3301
3302 /*
3303 * During initialization use the association count to spread out
3304 * the polls at one-second intervals. Unconfigured associations'
3305 * first poll is delayed by the "discard minimum" plus 1 to avoid
3306 * rate limiting. Other post-startup new or cleared associations
3307 * randomize the first poll over the minimum poll interval to
3308 * avoid implosion.
3309 */
3310 peer->nextdate = peer->update = peer->outdate = current_time;
3311 if (initializing) {
3312 peer->nextdate += peer_associations;
3313 } else if (!(FLAG_CONFIG & peer->flags)) {
3314 peer->nextdate += ntp_minpkt + 1;
3315 /* space out manycastclient first polls */
3316 if (peer->nextdate < earliest) {
3317 peer->nextdate = earliest;
3318 }
3319 earliest = peer->nextdate + 1;
3320 } else {
3321 peer->nextdate += ntp_random() % (1 << peer->minpoll);
3322 }
3323 #ifdef AUTOKEY
3324 peer->refresh = current_time + (1 << NTP_REFRESH);
3325 #endif /* AUTOKEY */
3326 DPRINTF(1, ("peer_clear: at %ld next %ld associd %d refid %s\n",
3327 current_time, peer->nextdate, peer->associd,
3328 ident));
3329 }
3330
3331
3332 /*
3333 * clock_filter - add incoming clock sample to filter register and run
3334 * the filter procedure to find the best sample.
3335 */
3336 void
clock_filter(struct peer * peer,double sample_offset,double sample_delay,double sample_disp)3337 clock_filter(
3338 struct peer *peer, /* peer structure pointer */
3339 double sample_offset, /* clock offset */
3340 double sample_delay, /* roundtrip delay */
3341 double sample_disp /* dispersion */
3342 )
3343 {
3344 double dst[NTP_SHIFT]; /* distance vector */
3345 u_char ord[NTP_SHIFT]; /* index vector */
3346 short i, j;
3347 u_char k, m;
3348 double dtemp, etemp;
3349
3350 /*
3351 * A sample consists of the offset, delay, dispersion and epoch
3352 * of arrival. The offset and delay are determined by the on-
3353 * wire protocol. The dispersion grows from the last outbound
3354 * packet to the arrival of this one increased by the sum of the
3355 * peer precision and the system precision as required by the
3356 * error budget. First, shift the new arrival into the shift
3357 * register discarding the oldest one.
3358 */
3359 j = peer->filter_nextpt;
3360 peer->filter_offset[j] = sample_offset;
3361 peer->filter_delay[j] = sample_delay;
3362 peer->filter_disp[j] = sample_disp;
3363 peer->filter_epoch[j] = current_time;
3364 j = (j + 1) % NTP_SHIFT;
3365 peer->filter_nextpt = (u_char)j;
3366
3367 /*
3368 * Update dispersions since the last update and at the same
3369 * time initialize the distance and index lists. Since samples
3370 * become increasingly uncorrelated beyond the Allan intercept,
3371 * only under exceptional cases will an older sample be used.
3372 * Therefore, the distance list uses a compound metric. If the
3373 * dispersion is greater than the maximum dispersion, clamp the
3374 * distance at that value. If the time since the last update is
3375 * less than the Allan intercept use the delay; otherwise, use
3376 * the sum of the delay and dispersion.
3377 */
3378 dtemp = clock_phi * (current_time - peer->update);
3379 peer->update = current_time;
3380 for (i = NTP_SHIFT - 1; i >= 0; i--) {
3381 if (i != 0)
3382 peer->filter_disp[j] += dtemp;
3383 if (peer->filter_disp[j] >= MAXDISPERSE) {
3384 peer->filter_disp[j] = MAXDISPERSE;
3385 dst[i] = MAXDISPERSE;
3386 } else if (peer->update - peer->filter_epoch[j] >
3387 (u_long)ULOGTOD(allan_xpt)) {
3388 dst[i] = peer->filter_delay[j] +
3389 peer->filter_disp[j];
3390 } else {
3391 dst[i] = peer->filter_delay[j];
3392 }
3393 ord[i] = (u_char)j;
3394 j = (j + 1) % NTP_SHIFT;
3395 }
3396
3397 /*
3398 * If the clock has stabilized, sort the samples by distance.
3399 */
3400 if (freq_cnt == 0) {
3401 for (i = 1; i < NTP_SHIFT; i++) {
3402 for (j = 0; j < i; j++) {
3403 if (dst[j] > dst[i]) {
3404 k = ord[j];
3405 ord[j] = ord[i];
3406 ord[i] = k;
3407 etemp = dst[j];
3408 dst[j] = dst[i];
3409 dst[i] = etemp;
3410 }
3411 }
3412 }
3413 }
3414
3415 /*
3416 * Copy the index list to the association structure so ntpq
3417 * can see it later. Prune the distance list to leave only
3418 * samples less than the maximum dispersion, which disfavors
3419 * uncorrelated samples older than the Allan intercept. To
3420 * further improve the jitter estimate, of the remainder leave
3421 * only samples less than the maximum distance, but keep at
3422 * least two samples for jitter calculation.
3423 */
3424 m = 0;
3425 for (i = 0; i < NTP_SHIFT; i++) {
3426 peer->filter_order[i] = ord[i];
3427 if ( dst[i] >= MAXDISPERSE
3428 || (m >= 2 && dst[i] >= sys_maxdist))
3429 continue;
3430 m++;
3431 }
3432
3433 /*
3434 * Compute the dispersion and jitter. The dispersion is weighted
3435 * exponentially by NTP_FWEIGHT (0.5) so it is normalized close
3436 * to 1.0. The jitter is the RMS differences relative to the
3437 * lowest delay sample.
3438 */
3439 peer->disp = peer->jitter = 0;
3440 k = ord[0];
3441 for (i = NTP_SHIFT - 1; i >= 0; i--) {
3442 j = ord[i];
3443 peer->disp = NTP_FWEIGHT * ( peer->disp
3444 + peer->filter_disp[j]);
3445 if (i < m) {
3446 peer->jitter += DIFF(peer->filter_offset[j],
3447 peer->filter_offset[k]);
3448 }
3449 }
3450
3451 /*
3452 * If no acceptable samples remain in the shift register,
3453 * quietly tiptoe home leaving only the dispersion. Otherwise,
3454 * save the offset, delay and jitter. Note the jitter must not
3455 * be less than the precision.
3456 */
3457 if (0 == m) {
3458 clock_select();
3459 return;
3460 }
3461 etemp = fabs(peer->offset - peer->filter_offset[k]);
3462 peer->offset = peer->filter_offset[k];
3463 peer->delay = peer->filter_delay[k];
3464 if (m > 1) {
3465 peer->jitter /= m - 1;
3466 }
3467 peer->jitter = max(SQRT(peer->jitter), LOGTOD(sys_precision));
3468
3469 /*
3470 * If the the new sample and the current sample are both valid
3471 * and the difference between their offsets exceeds CLOCK_SGATE
3472 * (3) times the jitter and the interval between them is less
3473 * than twice the host poll interval, consider the new sample
3474 * a popcorn spike and ignore it.
3475 */
3476 if ( peer->disp < sys_maxdist
3477 && peer->filter_disp[k] < sys_maxdist
3478 && etemp > CLOCK_SGATE * peer->jitter
3479 && peer->filter_epoch[k] - peer->epoch
3480 < 2. * ULOGTOD(peer->hpoll)) {
3481 mprintf_event(PEVNT_POPCORN, peer, "%.9f s", etemp);
3482 return;
3483 }
3484
3485 /*
3486 * A new minimum sample is useful only if it is later than the
3487 * last one used. In this design the maximum lifetime of any
3488 * sample is not greater than NTP_SHIFT (8) times the poll
3489 * interval, so the maximum interval between minimum samples is
3490 * NTP_SHIFT packets.
3491 */
3492 if (peer->filter_epoch[k] <= peer->epoch) {
3493 DPRINTF(2, ("clock_filter: old sample %lu s\n",
3494 current_time - peer->filter_epoch[k]));
3495 return;
3496 }
3497 peer->epoch = peer->filter_epoch[k];
3498
3499 /*
3500 * The mitigated sample statistics are saved for later
3501 * processing. If not synchronized or not in a burst, tickle the
3502 * clock select algorithm.
3503 */
3504 record_peer_stats(&peer->srcadr, ctlpeerstatus(peer), peer->offset,
3505 peer->delay, peer->disp, peer->jitter);
3506 DPRINTF(1, ("clock_filter: n %hu off %.9f del %.9f dsp %.9f jit %.9f\n",
3507 (u_short)m, peer->offset, peer->delay, peer->disp,
3508 peer->jitter));
3509 if (0 == peer->burst || LEAP_NOTINSYNC == sys_leap) {
3510 clock_select();
3511 }
3512 }
3513
3514
3515 /*
3516 * clock_select - find the pick-of-the-litter clock
3517 *
3518 * LOCKCLOCK: (1) If the local clock is the prefer peer, it will always
3519 * be enabled, even if declared falseticker, (2) only the prefer peer
3520 * can be selected as the system peer, (3) if the external source is
3521 * down, the system leap bits are set to 11 and the stratum set to
3522 * infinity.
3523 */
3524 void
clock_select(void)3525 clock_select(void)
3526 {
3527 struct peer *peer;
3528 int i, j, k, n;
3529 int nlist, nl2;
3530 int allow;
3531 int speer;
3532 double d, e, f, g;
3533 double high, low;
3534 double speermet;
3535 double lastresort_dist = MAXDISPERSE;
3536 double orphmet = 2.0 * U_INT32_MAX; /* 2x is greater than */
3537 struct endpoint endp;
3538 struct peer *osys_peer;
3539 struct peer *sys_prefer = NULL; /* prefer peer */
3540 struct peer *typesystem = NULL;
3541 struct peer *typelastresort = NULL;
3542 struct peer *typeorphan = NULL;
3543 #ifdef REFCLOCK
3544 struct peer *typeacts = NULL;
3545 struct peer *typelocal = NULL;
3546 struct peer *typepps = NULL;
3547 #endif /* REFCLOCK */
3548 static struct endpoint *endpoint = NULL;
3549 static int *indx = NULL;
3550 static peer_select *peers = NULL;
3551 static u_int endpoint_size = 0;
3552 static u_int peers_size = 0;
3553 static u_int indx_size = 0;
3554 size_t octets;
3555
3556 /*
3557 * Initialize and create endpoint, index and peer lists big
3558 * enough to handle all associations.
3559 */
3560 osys_peer = sys_peer;
3561 sys_survivors = 0;
3562 #ifdef LOCKCLOCK
3563 set_sys_leap(LEAP_NOTINSYNC);
3564 sys_stratum = STRATUM_UNSPEC;
3565 memcpy(&sys_refid, "DOWN", 4);
3566 #endif /* LOCKCLOCK */
3567
3568 /*
3569 * Allocate dynamic space depending on the number of
3570 * associations.
3571 */
3572 nlist = 1;
3573 for (peer = peer_list; peer != NULL; peer = peer->p_link)
3574 nlist++;
3575 endpoint_size = ALIGNED_SIZE(nlist * 2 * sizeof(*endpoint));
3576 peers_size = ALIGNED_SIZE(nlist * sizeof(*peers));
3577 indx_size = ALIGNED_SIZE(nlist * 2 * sizeof(*indx));
3578 octets = endpoint_size + peers_size + indx_size;
3579 endpoint = erealloc(endpoint, octets);
3580 peers = INC_ALIGNED_PTR(endpoint, endpoint_size);
3581 indx = INC_ALIGNED_PTR(peers, peers_size);
3582
3583 /*
3584 * Initially, we populate the island with all the rifraff peers
3585 * that happen to be lying around. Those with seriously
3586 * defective clocks are immediately booted off the island. Then,
3587 * the falsetickers are culled and put to sea. The truechimers
3588 * remaining are subject to repeated rounds where the most
3589 * unpopular at each round is kicked off. When the population
3590 * has dwindled to sys_minclock, the survivors split a million
3591 * bucks and collectively crank the chimes.
3592 */
3593 nlist = nl2 = 0; /* none yet */
3594 for (peer = peer_list; peer != NULL; peer = peer->p_link) {
3595 peer->new_status = CTL_PST_SEL_REJECT;
3596
3597 /*
3598 * Leave the island immediately if the peer is
3599 * unfit to synchronize.
3600 */
3601 if (peer_unfit(peer)) {
3602 continue;
3603 }
3604
3605 /*
3606 * If we have never been synchronised, look for any peer
3607 * which has ever been synchronised and pick the one which
3608 * has the lowest root distance. This can be used as a last
3609 * resort if all else fails. Once we get an initial sync
3610 * with this peer, sys_reftime gets set and so this
3611 * function becomes disabled.
3612 */
3613 if (L_ISZERO(&sys_reftime)) {
3614 d = root_distance(peer);
3615 if (!L_ISZERO(&peer->reftime) && d < lastresort_dist) {
3616 typelastresort = peer;
3617 lastresort_dist = d;
3618 }
3619 }
3620
3621 /*
3622 * If this peer is an orphan parent, elect the
3623 * one with the lowest metric defined as the
3624 * IPv4 address or the first 64 bits of the
3625 * hashed IPv6 address. To ensure convergence
3626 * on the same selected orphan, consider as
3627 * well that this system may have the lowest
3628 * metric and be the orphan parent. If this
3629 * system wins, sys_peer will be NULL to trigger
3630 * orphan mode in timer().
3631 */
3632 if (peer->stratum == sys_orphan) {
3633 u_int32 localmet;
3634 u_int32 peermet;
3635
3636 if (peer->dstadr != NULL)
3637 localmet = ntohl(peer->dstadr->addr_refid);
3638 else
3639 localmet = U_INT32_MAX;
3640 peermet = ntohl(addr2refid(&peer->srcadr));
3641 if (peermet < localmet && peermet < orphmet) {
3642 typeorphan = peer;
3643 orphmet = peermet;
3644 }
3645 continue;
3646 }
3647
3648 /*
3649 * If this peer could have the orphan parent
3650 * as a synchronization ancestor, exclude it
3651 * from selection to avoid forming a
3652 * synchronization loop within the orphan mesh,
3653 * triggering stratum climb to infinity
3654 * instability. Peers at stratum higher than
3655 * the orphan stratum could have the orphan
3656 * parent in ancestry so are excluded.
3657 * See http://bugs.ntp.org/2050
3658 */
3659 if (peer->stratum > sys_orphan) {
3660 continue;
3661 }
3662 #ifdef REFCLOCK
3663 /*
3664 * The following are special cases. We deal
3665 * with them later.
3666 */
3667 if (!(peer->flags & FLAG_PREFER)) {
3668 switch (peer->refclktype) {
3669 case REFCLK_LOCALCLOCK:
3670 if ( current_time > orphwait
3671 && typelocal == NULL)
3672 typelocal = peer;
3673 continue;
3674
3675 case REFCLK_ACTS:
3676 if ( current_time > orphwait
3677 && typeacts == NULL)
3678 typeacts = peer;
3679 continue;
3680 }
3681 }
3682 #endif /* REFCLOCK */
3683
3684 /*
3685 * If we get this far, the peer can stay on the
3686 * island, but does not yet have the immunity
3687 * idol.
3688 */
3689 peer->new_status = CTL_PST_SEL_SANE;
3690 f = root_distance(peer);
3691 peers[nlist].peer = peer;
3692 peers[nlist].error = peer->jitter;
3693 peers[nlist].synch = f;
3694 nlist++;
3695
3696 /*
3697 * Insert each interval endpoint on the unsorted
3698 * endpoint[] list.
3699 */
3700 e = peer->offset;
3701 endpoint[nl2].type = -1; /* lower end */
3702 endpoint[nl2].val = e - f;
3703 nl2++;
3704 endpoint[nl2].type = 1; /* upper end */
3705 endpoint[nl2].val = e + f;
3706 nl2++;
3707 }
3708 /*
3709 * Construct sorted indx[] of endpoint[] indexes ordered by
3710 * offset.
3711 */
3712 for (i = 0; i < nl2; i++)
3713 indx[i] = i;
3714 for (i = 0; i < nl2; i++) {
3715 endp = endpoint[indx[i]];
3716 e = endp.val;
3717 k = i;
3718 for (j = i + 1; j < nl2; j++) {
3719 endp = endpoint[indx[j]];
3720 if (endp.val < e) {
3721 e = endp.val;
3722 k = j;
3723 }
3724 }
3725 if (k != i) {
3726 j = indx[k];
3727 indx[k] = indx[i];
3728 indx[i] = j;
3729 }
3730 }
3731 for (i = 0; i < nl2; i++)
3732 DPRINTF(3, ("select: endpoint %2d %.6f\n",
3733 endpoint[indx[i]].type, endpoint[indx[i]].val));
3734
3735 /*
3736 * This is the actual algorithm that cleaves the truechimers
3737 * from the falsetickers. The original algorithm was described
3738 * in Keith Marzullo's dissertation, but has been modified for
3739 * better accuracy.
3740 *
3741 * Briefly put, we first assume there are no falsetickers, then
3742 * scan the candidate list first from the low end upwards and
3743 * then from the high end downwards. The scans stop when the
3744 * number of intersections equals the number of candidates less
3745 * the number of falsetickers. If this doesn't happen for a
3746 * given number of falsetickers, we bump the number of
3747 * falsetickers and try again. If the number of falsetickers
3748 * becomes equal to or greater than half the number of
3749 * candidates, the Albanians have won the Byzantine wars and
3750 * correct synchronization is not possible.
3751 *
3752 * Here, nlist is the number of candidates and allow is the
3753 * number of falsetickers. Upon exit, the truechimers are the
3754 * survivors with offsets not less than low and not greater than
3755 * high. There may be none of them.
3756 */
3757 low = 1e9;
3758 high = -1e9;
3759 for (allow = 0; 2 * allow < nlist; allow++) {
3760
3761 /*
3762 * Bound the interval (low, high) as the smallest
3763 * interval containing points from the most sources.
3764 */
3765 n = 0;
3766 for (i = 0; i < nl2; i++) {
3767 low = endpoint[indx[i]].val;
3768 n -= endpoint[indx[i]].type;
3769 if (n >= nlist - allow)
3770 break;
3771 }
3772 n = 0;
3773 for (j = nl2 - 1; j >= 0; j--) {
3774 high = endpoint[indx[j]].val;
3775 n += endpoint[indx[j]].type;
3776 if (n >= nlist - allow)
3777 break;
3778 }
3779
3780 /*
3781 * If an interval containing truechimers is found, stop.
3782 * If not, increase the number of falsetickers and go
3783 * around again.
3784 */
3785 if (high > low)
3786 break;
3787 }
3788
3789 /*
3790 * Clustering algorithm. Whittle candidate list of falsetickers,
3791 * who leave the island immediately. The TRUE peer is always a
3792 * truechimer. We must leave at least one peer to collect the
3793 * million bucks.
3794 *
3795 * We assert the correct time is contained in the interval, but
3796 * the best offset estimate for the interval might not be
3797 * contained in the interval. For this purpose, a truechimer is
3798 * defined as the midpoint of an interval that overlaps the
3799 * intersection interval.
3800 */
3801 j = 0;
3802 for (i = 0; i < nlist; i++) {
3803 double h;
3804
3805 peer = peers[i].peer;
3806 h = peers[i].synch;
3807 if (( high <= low
3808 || peer->offset + h < low
3809 || peer->offset - h > high
3810 ) && !(peer->flags & FLAG_TRUE))
3811 continue;
3812
3813 #ifdef REFCLOCK
3814 /*
3815 * Eligible PPS peers must survive the intersection
3816 * algorithm. Use the first one found, but don't
3817 * include any of them in the cluster population.
3818 */
3819 if (peer->flags & FLAG_PPS) {
3820 if (typepps == NULL)
3821 typepps = peer;
3822 if (!(peer->flags & FLAG_TSTAMP_PPS))
3823 continue;
3824 }
3825 #endif /* REFCLOCK */
3826
3827 if (j != i)
3828 peers[j] = peers[i];
3829 j++;
3830 }
3831 nlist = j;
3832
3833 /*
3834 * If no survivors remain at this point, check if the modem
3835 * driver, local driver or orphan parent in that order. If so,
3836 * nominate the first one found as the only survivor.
3837 * Otherwise, give up and leave the island to the rats.
3838 */
3839 if (nlist == 0) {
3840 peers[0].error = 0;
3841 peers[0].synch = sys_mindisp;
3842 #ifdef REFCLOCK
3843 if (typeacts != NULL) {
3844 peers[0].peer = typeacts;
3845 nlist = 1;
3846 } else if (typelocal != NULL) {
3847 peers[0].peer = typelocal;
3848 nlist = 1;
3849 } else
3850 #endif /* REFCLOCK */
3851 if (typeorphan != NULL) {
3852 peers[0].peer = typeorphan;
3853 nlist = 1;
3854 } else if (typelastresort != NULL) {
3855 peers[0].peer = typelastresort;
3856 nlist = 1;
3857 }
3858 }
3859
3860 /*
3861 * Mark the candidates at this point as truechimers.
3862 */
3863 for (i = 0; i < nlist; i++) {
3864 peers[i].peer->new_status = CTL_PST_SEL_SELCAND;
3865 DPRINTF(2, ("select: survivor %s %f\n",
3866 stoa(&peers[i].peer->srcadr), peers[i].synch));
3867 }
3868
3869 /*
3870 * Now, vote outliers off the island by select jitter weighted
3871 * by root distance. Continue voting as long as there are more
3872 * than sys_minclock survivors and the select jitter of the peer
3873 * with the worst metric is greater than the minimum peer
3874 * jitter. Stop if we are about to discard a TRUE or PREFER
3875 * peer, who of course have the immunity idol.
3876 */
3877 while (1) {
3878 d = 1e9;
3879 e = -1e9;
3880 g = 0;
3881 k = 0;
3882 for (i = 0; i < nlist; i++) {
3883 if (peers[i].error < d)
3884 d = peers[i].error;
3885 peers[i].seljit = 0;
3886 if (nlist > 1) {
3887 f = 0;
3888 for (j = 0; j < nlist; j++)
3889 f += DIFF(peers[j].peer->offset,
3890 peers[i].peer->offset);
3891 peers[i].seljit = SQRT(f / (nlist - 1));
3892 }
3893 if (peers[i].seljit * peers[i].synch > e) {
3894 g = peers[i].seljit;
3895 e = peers[i].seljit * peers[i].synch;
3896 k = i;
3897 }
3898 }
3899 g = max(g, LOGTOD(sys_precision));
3900 if ( nlist <= max(1, sys_minclock)
3901 || g <= d
3902 || ((FLAG_TRUE | FLAG_PREFER) & peers[k].peer->flags))
3903 break;
3904
3905 DPRINTF(3, ("select: drop %s seljit %.9f jit %.9f\n",
3906 ntoa(&peers[k].peer->srcadr), g, d));
3907 if (nlist > sys_maxclock)
3908 peers[k].peer->new_status = CTL_PST_SEL_EXCESS;
3909 for (j = k + 1; j < nlist; j++)
3910 peers[j - 1] = peers[j];
3911 nlist--;
3912 }
3913
3914 /*
3915 * What remains is a list usually not greater than sys_minclock
3916 * peers. Note that unsynchronized peers cannot survive this
3917 * far. Count and mark these survivors.
3918 *
3919 * While at it, count the number of leap warning bits found.
3920 * This will be used later to vote the system leap warning bit.
3921 * If a leap warning bit is found on a reference clock, the vote
3922 * is always won.
3923 *
3924 * Choose the system peer using a hybrid metric composed of the
3925 * selection jitter scaled by the root distance augmented by
3926 * stratum scaled by sys_mindisp (.001 by default). The goal of
3927 * the small stratum factor is to avoid clockhop between a
3928 * reference clock and a network peer which has a refclock and
3929 * is using an older ntpd, which does not floor sys_rootdisp at
3930 * sys_mindisp.
3931 *
3932 * In contrast, ntpd 4.2.6 and earlier used stratum primarily
3933 * in selecting the system peer, using a weight of 1 second of
3934 * additional root distance per stratum. This heavy bias is no
3935 * longer appropriate, as the scaled root distance provides a
3936 * more rational metric carrying the cumulative error budget.
3937 */
3938 e = 1e9;
3939 speer = 0;
3940 leap_vote_ins = 0;
3941 leap_vote_del = 0;
3942 for (i = 0; i < nlist; i++) {
3943 peer = peers[i].peer;
3944 peer->unreach = 0;
3945 peer->new_status = CTL_PST_SEL_SYNCCAND;
3946 sys_survivors++;
3947 if (peer->leap == LEAP_ADDSECOND) {
3948 if (peer->flags & FLAG_REFCLOCK)
3949 leap_vote_ins = nlist;
3950 else if (leap_vote_ins < nlist)
3951 leap_vote_ins++;
3952 }
3953 if (peer->leap == LEAP_DELSECOND) {
3954 if (peer->flags & FLAG_REFCLOCK)
3955 leap_vote_del = nlist;
3956 else if (leap_vote_del < nlist)
3957 leap_vote_del++;
3958 }
3959 if (peer->flags & FLAG_PREFER)
3960 sys_prefer = peer;
3961 speermet = peers[i].seljit * peers[i].synch +
3962 peer->stratum * sys_mindisp;
3963 if (speermet < e) {
3964 e = speermet;
3965 speer = i;
3966 }
3967 }
3968
3969 /*
3970 * Unless there are at least sys_misane survivors, leave the
3971 * building dark. Otherwise, do a clockhop dance. Ordinarily,
3972 * use the selected survivor speer. However, if the current
3973 * system peer is not speer, stay with the current system peer
3974 * as long as it doesn't get too old or too ugly.
3975 */
3976 if (nlist > 0 && nlist >= sys_minsane) {
3977 double x;
3978
3979 typesystem = peers[speer].peer;
3980 if (osys_peer == NULL || osys_peer == typesystem) {
3981 sys_clockhop = 0;
3982 } else if ((x = fabs(typesystem->offset -
3983 osys_peer->offset)) < sys_mindisp) {
3984 if (0 == sys_clockhop)
3985 sys_clockhop = sys_mindisp;
3986 else
3987 sys_clockhop *= .5;
3988 DPRINTF(1, ("select: clockhop %d %.9f %.9f\n",
3989 j, x, sys_clockhop));
3990 if (x < sys_clockhop)
3991 typesystem = osys_peer;
3992 else
3993 sys_clockhop = 0;
3994 } else {
3995 sys_clockhop = 0;
3996 }
3997 }
3998
3999 /*
4000 * Mitigation rules of the game. We have the pick of the
4001 * litter in typesystem if any survivors are left. If
4002 * there is a prefer peer, use its offset and jitter.
4003 * Otherwise, use the combined offset and jitter of all kitters.
4004 */
4005 if (typesystem != NULL) {
4006 if (sys_prefer == NULL) {
4007 typesystem->new_status = CTL_PST_SEL_SYSPEER;
4008 clock_combine(peers, sys_survivors, speer);
4009 } else {
4010 typesystem = sys_prefer;
4011 sys_clockhop = 0;
4012 typesystem->new_status = CTL_PST_SEL_SYSPEER;
4013 sys_offset = typesystem->offset;
4014 sys_jitter = typesystem->jitter;
4015 }
4016 DPRINTF(1, ("select: combine offset %.9f jitter %.9f\n",
4017 sys_offset, sys_jitter));
4018 }
4019 #ifdef REFCLOCK
4020 /*
4021 * If a PPS driver is lit and the combined offset is less than
4022 * 0.4 s, select the driver as the PPS peer and use its offset
4023 * and jitter. However, if this is the atom driver, use it only
4024 * if there is a prefer peer or there are no survivors and none
4025 * are required.
4026 */
4027 if ( typepps != NULL
4028 && fabs(sys_offset) < 0.4
4029 && ( typepps->refclktype != REFCLK_ATOM_PPS
4030 || ( typepps->refclktype == REFCLK_ATOM_PPS
4031 && ( sys_prefer != NULL
4032 || (typesystem == NULL && sys_minsane == 0))))) {
4033 typesystem = typepps;
4034 sys_clockhop = 0;
4035 typesystem->new_status = CTL_PST_SEL_PPS;
4036 sys_offset = typesystem->offset;
4037 sys_jitter = typesystem->jitter;
4038 DPRINTF(1, ("select: pps offset %.9f jitter %.9f\n",
4039 sys_offset, sys_jitter));
4040 }
4041 #endif /* REFCLOCK */
4042
4043 /*
4044 * If there are no survivors at this point, there is no
4045 * system peer. If so and this is an old update, keep the
4046 * current statistics, but do not update the clock.
4047 */
4048 if (typesystem == NULL) {
4049 if (osys_peer != NULL) {
4050 orphwait = current_time + sys_orphwait;
4051 report_event(EVNT_NOPEER, NULL, NULL);
4052 }
4053 sys_peer = NULL;
4054 for (peer = peer_list; peer != NULL; peer = peer->p_link)
4055 peer->status = peer->new_status;
4056 return;
4057 }
4058
4059 /*
4060 * Do not use old data, as this may mess up the clock discipline
4061 * stability.
4062 */
4063 if (typesystem->epoch <= sys_epoch)
4064 return;
4065
4066 /*
4067 * We have found the alpha male. Wind the clock.
4068 */
4069 if (osys_peer != typesystem)
4070 report_event(PEVNT_NEWPEER, typesystem, NULL);
4071 for (peer = peer_list; peer != NULL; peer = peer->p_link)
4072 peer->status = peer->new_status;
4073 clock_update(typesystem);
4074 }
4075
4076
4077 static void
clock_combine(peer_select * peers,int npeers,int syspeer)4078 clock_combine(
4079 peer_select * peers, /* survivor list */
4080 int npeers, /* number of survivors */
4081 int syspeer /* index of sys.peer */
4082 )
4083 {
4084 int i;
4085 double x, y, z, w;
4086
4087 y = z = w = 0;
4088 for (i = 0; i < npeers; i++) {
4089 x = 1. / peers[i].synch;
4090 y += x;
4091 z += x * peers[i].peer->offset;
4092 w += x * DIFF(peers[i].peer->offset,
4093 peers[syspeer].peer->offset);
4094 }
4095 sys_offset = z / y;
4096 sys_jitter = SQRT(w / y + SQUARE(peers[syspeer].seljit));
4097 }
4098
4099
4100 /*
4101 * root_distance - compute synchronization distance from peer to root
4102 */
4103 static double
root_distance(struct peer * peer)4104 root_distance(
4105 struct peer *peer /* peer structure pointer */
4106 )
4107 {
4108 double dtemp;
4109
4110 /*
4111 * Root Distance (LAMBDA) is defined as:
4112 * (delta + DELTA)/2 + epsilon + EPSILON + D
4113 *
4114 * where:
4115 * delta is the round-trip delay
4116 * DELTA is the root delay
4117 * epsilon is the peer dispersion
4118 * + (15 usec each second)
4119 * EPSILON is the root dispersion
4120 * D is sys_jitter
4121 *
4122 * NB: Think hard about why we are using these values, and what
4123 * the alternatives are, and the various pros/cons.
4124 *
4125 * DLM thinks these are probably the best choices from any of the
4126 * other worse choices.
4127 */
4128 dtemp = (peer->delay + peer->rootdelay) / 2
4129 + peer->disp
4130 + clock_phi * (current_time - peer->update)
4131 + peer->rootdisp
4132 + peer->jitter;
4133 /*
4134 * Careful squeak here. The value returned must be greater than
4135 * the minimum root dispersion in order to avoid clockhop with
4136 * highly precise reference clocks. Note that the root distance
4137 * cannot exceed the sys_maxdist, as this is the cutoff by the
4138 * selection algorithm.
4139 */
4140 if (dtemp < sys_mindisp)
4141 dtemp = sys_mindisp;
4142 return (dtemp);
4143 }
4144
4145
4146 /*
4147 * peer_xmit - send packet for persistent association.
4148 */
4149 static void
peer_xmit(struct peer * peer)4150 peer_xmit(
4151 struct peer *peer /* peer structure pointer */
4152 )
4153 {
4154 struct pkt xpkt; /* transmit packet */
4155 size_t sendlen, authlen;
4156 keyid_t xkeyid = 0; /* transmit key ID */
4157 l_fp xmt_tx, xmt_ty;
4158
4159 if (!peer->dstadr) { /* can't send */
4160 return;
4161 }
4162 xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, peer->version,
4163 peer->hmode);
4164 xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
4165 xpkt.ppoll = peer->hpoll;
4166 xpkt.precision = sys_precision;
4167 xpkt.refid = sys_refid;
4168 xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
4169 xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp));
4170 /* Use sys_reftime for peer exchanges */
4171 HTONL_FP(&sys_reftime, &xpkt.reftime);
4172 HTONL_FP(&peer->rec, &xpkt.org);
4173 HTONL_FP(&peer->dst, &xpkt.rec);
4174
4175 /*
4176 * If the received packet contains a MAC, the transmitted packet
4177 * is authenticated and contains a MAC. If not, the transmitted
4178 * packet is not authenticated.
4179 *
4180 * It is most important when autokey is in use that the local
4181 * interface IP address be known before the first packet is
4182 * sent. Otherwise, it is not possible to compute a correct MAC
4183 * the recipient will accept. Thus, the I/O semantics have to do
4184 * a little more work. In particular, the wildcard interface
4185 * might not be usable.
4186 */
4187 sendlen = LEN_PKT_NOMAC;
4188 if (
4189 #ifdef AUTOKEY
4190 !(peer->flags & FLAG_SKEY) &&
4191 #endif /* !AUTOKEY */
4192 peer->keyid == 0) {
4193
4194 /*
4195 * Transmit a-priori timestamps
4196 */
4197 get_systime(&xmt_tx);
4198 if (peer->flip == 0) { /* basic mode */
4199 peer->aorg = xmt_tx;
4200 HTONL_FP(&xmt_tx, &xpkt.xmt);
4201 } else { /* interleaved modes */
4202 if (peer->hmode == MODE_BROADCAST) { /* bcst */
4203 HTONL_FP(&xmt_tx, &xpkt.xmt);
4204 if (peer->flip > 0)
4205 HTONL_FP(&peer->borg,
4206 &xpkt.org);
4207 else
4208 HTONL_FP(&peer->aorg,
4209 &xpkt.org);
4210 } else { /* symmetric */
4211 if (peer->flip > 0)
4212 HTONL_FP(&peer->borg,
4213 &xpkt.xmt);
4214 else
4215 HTONL_FP(&peer->aorg,
4216 &xpkt.xmt);
4217 }
4218 }
4219 peer->t21_bytes = sendlen;
4220 sendpkt(&peer->srcadr, peer->dstadr,
4221 sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : peer->ttl],
4222 &xpkt, sendlen);
4223 peer->sent++;
4224 peer->throttle += (1 << peer->minpoll) - 2;
4225
4226 /*
4227 * Capture a-posteriori timestamps
4228 */
4229 get_systime(&xmt_ty);
4230 if (peer->flip != 0) { /* interleaved modes */
4231 if (peer->flip > 0)
4232 peer->aorg = xmt_ty;
4233 else
4234 peer->borg = xmt_ty;
4235 peer->flip = -peer->flip;
4236 }
4237 L_SUB(&xmt_ty, &xmt_tx);
4238 LFPTOD(&xmt_ty, peer->xleave);
4239 DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d len %zu xmt 0x%x.%08x\n",
4240 current_time, latoa(peer->dstadr),
4241 stoa(&peer->srcadr), peer->hmode, sendlen,
4242 xmt_tx.l_ui, xmt_tx.l_uf));
4243 return;
4244 }
4245
4246 /*
4247 * Authentication is enabled, so the transmitted packet must be
4248 * authenticated. If autokey is enabled, fuss with the various
4249 * modes; otherwise, symmetric key cryptography is used.
4250 */
4251 #ifdef AUTOKEY
4252 if (peer->flags & FLAG_SKEY) {
4253 struct exten *exten; /* extension field */
4254
4255 /*
4256 * The Public Key Dance (PKD): Cryptographic credentials
4257 * are contained in extension fields, each including a
4258 * 4-octet length/code word followed by a 4-octet
4259 * association ID and optional additional data. Optional
4260 * data includes a 4-octet data length field followed by
4261 * the data itself. Request messages are sent from a
4262 * configured association; response messages can be sent
4263 * from a configured association or can take the fast
4264 * path without ever matching an association. Response
4265 * messages have the same code as the request, but have
4266 * a response bit and possibly an error bit set. In this
4267 * implementation, a message may contain no more than
4268 * one command and one or more responses.
4269 *
4270 * Cryptographic session keys include both a public and
4271 * a private componet. Request and response messages
4272 * using extension fields are always sent with the
4273 * private component set to zero. Packets without
4274 * extension fields indlude the private component when
4275 * the session key is generated.
4276 */
4277 while (1) {
4278
4279 /*
4280 * Allocate and initialize a keylist if not
4281 * already done. Then, use the list in inverse
4282 * order, discarding keys once used. Keep the
4283 * latest key around until the next one, so
4284 * clients can use client/server packets to
4285 * compute propagation delay.
4286 *
4287 * Note that once a key is used from the list,
4288 * it is retained in the key cache until the
4289 * next key is used. This is to allow a client
4290 * to retrieve the encrypted session key
4291 * identifier to verify authenticity.
4292 *
4293 * If for some reason a key is no longer in the
4294 * key cache, a birthday has happened or the key
4295 * has expired, so the pseudo-random sequence is
4296 * broken. In that case, purge the keylist and
4297 * regenerate it.
4298 */
4299 if (peer->keynumber == 0)
4300 make_keylist(peer, peer->dstadr);
4301 else
4302 peer->keynumber--;
4303 xkeyid = peer->keylist[peer->keynumber];
4304 if (authistrusted(xkeyid))
4305 break;
4306 else
4307 key_expire(peer);
4308 }
4309 peer->keyid = xkeyid;
4310 exten = NULL;
4311 switch (peer->hmode) {
4312
4313 /*
4314 * In broadcast server mode the autokey values are
4315 * required by the broadcast clients. Push them when a
4316 * new keylist is generated; otherwise, push the
4317 * association message so the client can request them at
4318 * other times.
4319 */
4320 case MODE_BROADCAST:
4321 if (peer->flags & FLAG_ASSOC)
4322 exten = crypto_args(peer, CRYPTO_AUTO |
4323 CRYPTO_RESP, peer->associd, NULL);
4324 else
4325 exten = crypto_args(peer, CRYPTO_ASSOC |
4326 CRYPTO_RESP, peer->associd, NULL);
4327 break;
4328
4329 /*
4330 * In symmetric modes the parameter, certificate,
4331 * identity, cookie and autokey exchanges are
4332 * required. The leapsecond exchange is optional. But, a
4333 * peer will not believe the other peer until the other
4334 * peer has synchronized, so the certificate exchange
4335 * might loop until then. If a peer finds a broken
4336 * autokey sequence, it uses the autokey exchange to
4337 * retrieve the autokey values. In any case, if a new
4338 * keylist is generated, the autokey values are pushed.
4339 */
4340 case MODE_ACTIVE:
4341 case MODE_PASSIVE:
4342
4343 /*
4344 * Parameter, certificate and identity.
4345 */
4346 if (!peer->crypto)
4347 exten = crypto_args(peer, CRYPTO_ASSOC,
4348 peer->associd, hostval.ptr);
4349 else if (!(peer->crypto & CRYPTO_FLAG_CERT))
4350 exten = crypto_args(peer, CRYPTO_CERT,
4351 peer->associd, peer->issuer);
4352 else if (!(peer->crypto & CRYPTO_FLAG_VRFY))
4353 exten = crypto_args(peer,
4354 crypto_ident(peer), peer->associd,
4355 NULL);
4356
4357 /*
4358 * Cookie and autokey. We request the cookie
4359 * only when the this peer and the other peer
4360 * are synchronized. But, this peer needs the
4361 * autokey values when the cookie is zero. Any
4362 * time we regenerate the key list, we offer the
4363 * autokey values without being asked. If for
4364 * some reason either peer finds a broken
4365 * autokey sequence, the autokey exchange is
4366 * used to retrieve the autokey values.
4367 */
4368 else if ( sys_leap != LEAP_NOTINSYNC
4369 && peer->leap != LEAP_NOTINSYNC
4370 && !(peer->crypto & CRYPTO_FLAG_COOK))
4371 exten = crypto_args(peer, CRYPTO_COOK,
4372 peer->associd, NULL);
4373 else if (!(peer->crypto & CRYPTO_FLAG_AUTO))
4374 exten = crypto_args(peer, CRYPTO_AUTO,
4375 peer->associd, NULL);
4376 else if ( peer->flags & FLAG_ASSOC
4377 && peer->crypto & CRYPTO_FLAG_SIGN)
4378 exten = crypto_args(peer, CRYPTO_AUTO |
4379 CRYPTO_RESP, peer->assoc, NULL);
4380
4381 /*
4382 * Wait for clock sync, then sign the
4383 * certificate and retrieve the leapsecond
4384 * values.
4385 */
4386 else if (sys_leap == LEAP_NOTINSYNC)
4387 break;
4388
4389 else if (!(peer->crypto & CRYPTO_FLAG_SIGN))
4390 exten = crypto_args(peer, CRYPTO_SIGN,
4391 peer->associd, hostval.ptr);
4392 else if (!(peer->crypto & CRYPTO_FLAG_LEAP))
4393 exten = crypto_args(peer, CRYPTO_LEAP,
4394 peer->associd, NULL);
4395 break;
4396
4397 /*
4398 * In client mode the parameter, certificate, identity,
4399 * cookie and sign exchanges are required. The
4400 * leapsecond exchange is optional. If broadcast client
4401 * mode the same exchanges are required, except that the
4402 * autokey exchange is substitutes for the cookie
4403 * exchange, since the cookie is always zero. If the
4404 * broadcast client finds a broken autokey sequence, it
4405 * uses the autokey exchange to retrieve the autokey
4406 * values.
4407 */
4408 case MODE_CLIENT:
4409
4410 /*
4411 * Parameter, certificate and identity.
4412 */
4413 if (!peer->crypto)
4414 exten = crypto_args(peer, CRYPTO_ASSOC,
4415 peer->associd, hostval.ptr);
4416 else if (!(peer->crypto & CRYPTO_FLAG_CERT))
4417 exten = crypto_args(peer, CRYPTO_CERT,
4418 peer->associd, peer->issuer);
4419 else if (!(peer->crypto & CRYPTO_FLAG_VRFY))
4420 exten = crypto_args(peer,
4421 crypto_ident(peer), peer->associd,
4422 NULL);
4423
4424 /*
4425 * Cookie and autokey. These are requests, but
4426 * we use the peer association ID with autokey
4427 * rather than our own.
4428 */
4429 else if (!(peer->crypto & CRYPTO_FLAG_COOK))
4430 exten = crypto_args(peer, CRYPTO_COOK,
4431 peer->associd, NULL);
4432 else if (!(peer->crypto & CRYPTO_FLAG_AUTO))
4433 exten = crypto_args(peer, CRYPTO_AUTO,
4434 peer->assoc, NULL);
4435
4436 /*
4437 * Wait for clock sync, then sign the
4438 * certificate and retrieve the leapsecond
4439 * values.
4440 */
4441 else if (sys_leap == LEAP_NOTINSYNC)
4442 break;
4443
4444 else if (!(peer->crypto & CRYPTO_FLAG_SIGN))
4445 exten = crypto_args(peer, CRYPTO_SIGN,
4446 peer->associd, hostval.ptr);
4447 else if (!(peer->crypto & CRYPTO_FLAG_LEAP))
4448 exten = crypto_args(peer, CRYPTO_LEAP,
4449 peer->associd, NULL);
4450 break;
4451 }
4452
4453 /*
4454 * Add a queued extension field if present. This is
4455 * always a request message, so the reply ID is already
4456 * in the message. If an error occurs, the error bit is
4457 * lit in the response.
4458 */
4459 if (peer->cmmd != NULL) {
4460 u_int32 temp32;
4461
4462 temp32 = CRYPTO_RESP;
4463 peer->cmmd->opcode |= htonl(temp32);
4464 sendlen += crypto_xmit(peer, &xpkt, NULL,
4465 sendlen, peer->cmmd, 0);
4466 free(peer->cmmd);
4467 peer->cmmd = NULL;
4468 }
4469
4470 /*
4471 * Add an extension field created above. All but the
4472 * autokey response message are request messages.
4473 */
4474 if (exten != NULL) {
4475 if (exten->opcode != 0)
4476 sendlen += crypto_xmit(peer, &xpkt,
4477 NULL, sendlen, exten, 0);
4478 free(exten);
4479 }
4480
4481 /*
4482 * Calculate the next session key. Since extension
4483 * fields are present, the cookie value is zero.
4484 */
4485 if (sendlen > (int)LEN_PKT_NOMAC) {
4486 session_key(&peer->dstadr->sin, &peer->srcadr,
4487 xkeyid, 0, 2);
4488 }
4489 }
4490 #endif /* AUTOKEY */
4491
4492 /*
4493 * Transmit a-priori timestamps
4494 */
4495 get_systime(&xmt_tx);
4496 if (peer->flip == 0) { /* basic mode */
4497 peer->aorg = xmt_tx;
4498 HTONL_FP(&xmt_tx, &xpkt.xmt);
4499 } else { /* interleaved modes */
4500 if (peer->hmode == MODE_BROADCAST) { /* bcst */
4501 HTONL_FP(&xmt_tx, &xpkt.xmt);
4502 if (peer->flip > 0)
4503 HTONL_FP(&peer->borg, &xpkt.org);
4504 else
4505 HTONL_FP(&peer->aorg, &xpkt.org);
4506 } else { /* symmetric */
4507 if (peer->flip > 0)
4508 HTONL_FP(&peer->borg, &xpkt.xmt);
4509 else
4510 HTONL_FP(&peer->aorg, &xpkt.xmt);
4511 }
4512 }
4513 xkeyid = peer->keyid;
4514 authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
4515 if (authlen == 0) {
4516 report_event(PEVNT_AUTH, peer, "no key");
4517 peer->flash |= TEST5; /* auth error */
4518 peer->badauth++;
4519 return;
4520 }
4521 sendlen += authlen;
4522 #ifdef AUTOKEY
4523 if (xkeyid > NTP_MAXKEY)
4524 authtrust(xkeyid, 0);
4525 #endif /* AUTOKEY */
4526 if (sendlen > sizeof(xpkt)) {
4527 msyslog(LOG_ERR, "peer_xmit: buffer overflow %u", (u_int)sendlen);
4528 exit(EX_SOFTWARE);
4529 }
4530 peer->t21_bytes = sendlen;
4531 sendpkt(&peer->srcadr, peer->dstadr,
4532 sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : peer->ttl],
4533 &xpkt, sendlen);
4534 peer->sent++;
4535 peer->throttle += (1 << peer->minpoll) - 2;
4536
4537 /*
4538 * Capture a-posteriori timestamps
4539 */
4540 get_systime(&xmt_ty);
4541 if (peer->flip != 0) { /* interleaved modes */
4542 if (peer->flip > 0)
4543 peer->aorg = xmt_ty;
4544 else
4545 peer->borg = xmt_ty;
4546 peer->flip = -peer->flip;
4547 }
4548 L_SUB(&xmt_ty, &xmt_tx);
4549 LFPTOD(&xmt_ty, peer->xleave);
4550 #ifdef AUTOKEY
4551 DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu index %d\n",
4552 current_time, latoa(peer->dstadr), stoa(&peer->srcadr),
4553 peer->hmode, xkeyid, sendlen, peer->keynumber));
4554 #else /* !AUTOKEY follows */
4555 DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu\n",
4556 current_time, peer->dstadr ?
4557 ntoa(&peer->dstadr->sin) : "-",
4558 ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen));
4559 #endif /* !AUTOKEY */
4560
4561 return;
4562 }
4563
4564
4565 #ifdef LEAP_SMEAR
4566
4567 static void
leap_smear_add_offs(l_fp * t,l_fp * t_recv)4568 leap_smear_add_offs(
4569 l_fp *t,
4570 l_fp *t_recv
4571 )
4572 {
4573
4574 L_ADD(t, &leap_smear.offset);
4575
4576 /*
4577 ** XXX: Should the smear be added to the root dispersion?
4578 */
4579
4580 return;
4581 }
4582
4583 #endif /* LEAP_SMEAR */
4584
4585
4586 /*
4587 * fast_xmit - Send packet for nonpersistent association. Note that
4588 * neither the source or destination can be a broadcast address.
4589 */
4590 static void
fast_xmit(struct recvbuf * rbufp,int xmode,keyid_t xkeyid,int flags)4591 fast_xmit(
4592 struct recvbuf* rbufp, /* receive packet pointer */
4593 int xmode, /* receive mode */ /* XXX: HMS: really? */
4594 keyid_t xkeyid, /* transmit key ID */
4595 int flags /* restrict mask */
4596 )
4597 {
4598 struct pkt xpkt; /* transmit packet structure */
4599 struct pkt* rpkt; /* receive packet structure */
4600 l_fp xmt_tx, xmt_ty;
4601 size_t sendlen;
4602 #ifdef AUTOKEY
4603 u_int32 temp32;
4604 #endif
4605
4606 /*
4607 * Initialize transmit packet header fields from the receive
4608 * buffer provided. We leave the fields intact as received, but
4609 * set the peer poll at the maximum of the receive peer poll and
4610 * the system minimum poll (ntp_minpoll). This is for KoD rate
4611 * control and not strictly specification compliant, but doesn't
4612 * break anything.
4613 */
4614 rpkt = &rbufp->recv_pkt;
4615 /*
4616 * If the packet was received on an endpoint open only on
4617 * a multicast address, the response needs to go out from
4618 * a unicast endpoint.
4619 */
4620 #ifndef MULTICAST_NONEWSOCKET
4621 if (rbufp->dstadr->flags & INT_MCASTOPEN) {
4622 rbufp->dstadr = findinterface(&rbufp->recv_srcadr);
4623 if (NULL == rbufp->dstadr ||
4624 ANY_INTERFACE_CHOOSE(&rbufp->recv_srcadr) /* wildcard */
4625 == rbufp->dstadr) {
4626 DPRINTF(2, ("No unicast local address found for"
4627 " reply to %s mcast.",
4628 stoa(&rbufp->recv_srcadr)));
4629 return;
4630 }
4631 }
4632 #endif
4633
4634 /*
4635 * If this is a kiss-o'-death (KoD) packet, show leap
4636 * unsynchronized, stratum zero, reference ID the four-character
4637 * kiss code and (???) system root delay. Note we don't reveal
4638 * the local time, so these packets can't be used for
4639 * synchronization.
4640 */
4641 if (flags & RES_KOD) {
4642 sys_kodsent++;
4643 xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC,
4644 PKT_VERSION(rpkt->li_vn_mode), xmode);
4645 xpkt.stratum = STRATUM_PKT_UNSPEC;
4646 xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll);
4647 xpkt.precision = rpkt->precision;
4648 memcpy(&xpkt.refid, "RATE", 4);
4649 xpkt.rootdelay = rpkt->rootdelay;
4650 xpkt.rootdisp = rpkt->rootdisp;
4651 xpkt.reftime = rpkt->reftime;
4652 xpkt.org = rpkt->xmt;
4653 xpkt.rec = rpkt->xmt;
4654 xpkt.xmt = rpkt->xmt;
4655
4656 /*
4657 * This is a normal packet. Use the system variables.
4658 */
4659 } else {
4660 double this_rootdisp;
4661 l_fp this_ref_time;
4662
4663 #ifdef LEAP_SMEAR
4664 /*
4665 * Make copies of the variables which can be affected by smearing.
4666 */
4667 l_fp this_recv_time;
4668 #endif
4669
4670 /*
4671 * If we are inside the leap smear interval we add
4672 * the current smear offset to:
4673 * - the packet receive time,
4674 * - the packet transmit time,
4675 * - and eventually to the reftime to make sure the
4676 * reftime isn't later than the transmit/receive times.
4677 */
4678 xpkt.li_vn_mode = PKT_LI_VN_MODE(xmt_leap,
4679 PKT_VERSION(rpkt->li_vn_mode), xmode);
4680
4681 xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
4682 xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll);
4683 xpkt.precision = sys_precision;
4684 xpkt.refid = sys_refid;
4685 xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
4686
4687 /*
4688 ** Server Response Fuzzing
4689 **
4690 ** Which values do we want to use for reftime and rootdisp?
4691 */
4692
4693 if ( MODE_SERVER == xmode
4694 && RES_SRVRSPFUZ & flags) {
4695 if (current_time < p2_time) {
4696 this_ref_time = p2_reftime;
4697 this_rootdisp = p2_rootdisp;
4698 } else if (current_time < prev_time) {
4699 this_ref_time = prev_reftime;
4700 this_rootdisp = prev_rootdisp;
4701 } else {
4702 this_ref_time = sys_reftime;
4703 this_rootdisp = sys_rootdisp;
4704 }
4705
4706 SRVRSP_FUZZ(this_ref_time);
4707 } else {
4708 this_ref_time = sys_reftime;
4709 this_rootdisp = sys_rootdisp;
4710 }
4711
4712 /*
4713 ** ROOT DISPERSION
4714 */
4715
4716 xpkt.rootdisp = HTONS_FP(DTOUFP(this_rootdisp));
4717
4718 /*
4719 ** REFTIME
4720 */
4721
4722 #ifdef LEAP_SMEAR
4723 if (leap_smear.in_progress) {
4724 /* adjust the reftime by the same amount as the
4725 * leap smear, as we don't want to risk the
4726 * reftime being later than the transmit time.
4727 */
4728 leap_smear_add_offs(&this_ref_time, NULL);
4729 }
4730 #endif
4731
4732 HTONL_FP(&this_ref_time, &xpkt.reftime);
4733
4734 /*
4735 ** REFID
4736 */
4737
4738 #ifdef LEAP_SMEAR
4739 if (leap_smear.in_progress) {
4740 xpkt.refid = convertLFPToRefID(leap_smear.offset);
4741 DPRINTF(2, ("fast_xmit: leap_smear.in_progress: refid %8x, smear %s\n",
4742 ntohl(xpkt.refid),
4743 lfptoa(&leap_smear.offset, 8)
4744 ));
4745 }
4746 #endif
4747
4748 /*
4749 ** ORIGIN
4750 */
4751
4752 xpkt.org = rpkt->xmt;
4753
4754 /*
4755 ** RECEIVE
4756 */
4757 #ifdef LEAP_SMEAR
4758 this_recv_time = rbufp->recv_time;
4759 if (leap_smear.in_progress)
4760 leap_smear_add_offs(&this_recv_time, NULL);
4761 HTONL_FP(&this_recv_time, &xpkt.rec);
4762 #else
4763 HTONL_FP(&rbufp->recv_time, &xpkt.rec);
4764 #endif
4765
4766 /*
4767 ** TRANSMIT
4768 */
4769
4770 get_systime(&xmt_tx);
4771 #ifdef LEAP_SMEAR
4772 if (leap_smear.in_progress)
4773 leap_smear_add_offs(&xmt_tx, &this_recv_time);
4774 #endif
4775 HTONL_FP(&xmt_tx, &xpkt.xmt);
4776 }
4777
4778 #ifdef HAVE_NTP_SIGND
4779 if (flags & RES_MSSNTP) {
4780 send_via_ntp_signd(rbufp, xmode, xkeyid, flags, &xpkt);
4781 return;
4782 }
4783 #endif /* HAVE_NTP_SIGND */
4784
4785 /*
4786 * If the received packet contains a MAC, the transmitted packet
4787 * is authenticated and contains a MAC. If not, the transmitted
4788 * packet is not authenticated.
4789 */
4790 sendlen = LEN_PKT_NOMAC;
4791 if ((size_t)rbufp->recv_length == sendlen) {
4792 sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt,
4793 sendlen);
4794 DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d len %lu\n",
4795 current_time, stoa(&rbufp->dstadr->sin),
4796 stoa(&rbufp->recv_srcadr), xmode,
4797 (u_long)sendlen));
4798 return;
4799 }
4800
4801 /*
4802 * The received packet contains a MAC, so the transmitted packet
4803 * must be authenticated. For symmetric key cryptography, use
4804 * the predefined and trusted symmetric keys to generate the
4805 * cryptosum. For autokey cryptography, use the server private
4806 * value to generate the cookie, which is unique for every
4807 * source-destination-key ID combination.
4808 */
4809 #ifdef AUTOKEY
4810 if (xkeyid > NTP_MAXKEY) {
4811 keyid_t cookie;
4812
4813 /*
4814 * The only way to get here is a reply to a legitimate
4815 * client request message, so the mode must be
4816 * MODE_SERVER. If an extension field is present, there
4817 * can be only one and that must be a command. Do what
4818 * needs, but with private value of zero so the poor
4819 * jerk can decode it. If no extension field is present,
4820 * use the cookie to generate the session key.
4821 */
4822 cookie = session_key(&rbufp->recv_srcadr,
4823 &rbufp->dstadr->sin, 0, sys_private, 0);
4824 if ((size_t)rbufp->recv_length > sendlen + MAX_MAC_LEN) {
4825 session_key(&rbufp->dstadr->sin,
4826 &rbufp->recv_srcadr, xkeyid, 0, 2);
4827 temp32 = CRYPTO_RESP;
4828 rpkt->exten[0] |= htonl(temp32);
4829 sendlen += crypto_xmit(NULL, &xpkt, rbufp,
4830 sendlen, (struct exten *)rpkt->exten,
4831 cookie);
4832 } else {
4833 session_key(&rbufp->dstadr->sin,
4834 &rbufp->recv_srcadr, xkeyid, cookie, 2);
4835 }
4836 }
4837 #endif /* AUTOKEY */
4838 get_systime(&xmt_tx);
4839 sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen);
4840 #ifdef AUTOKEY
4841 if (xkeyid > NTP_MAXKEY)
4842 authtrust(xkeyid, 0);
4843 #endif /* AUTOKEY */
4844 sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen);
4845 get_systime(&xmt_ty);
4846 L_SUB(&xmt_ty, &xmt_tx);
4847 sys_authdelay = xmt_ty;
4848 DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d keyid %08x len %lu\n",
4849 current_time, ntoa(&rbufp->dstadr->sin),
4850 ntoa(&rbufp->recv_srcadr), xmode, xkeyid,
4851 (u_long)sendlen));
4852 }
4853
4854
4855 /*
4856 * pool_xmit - resolve hostname or send unicast solicitation for pool.
4857 */
4858 static void
pool_xmit(struct peer * pool)4859 pool_xmit(
4860 struct peer *pool /* pool solicitor association */
4861 )
4862 {
4863 #ifdef WORKER
4864 struct pkt xpkt; /* transmit packet structure */
4865 struct addrinfo hints;
4866 int rc;
4867 endpt * lcladr;
4868 sockaddr_u * rmtadr;
4869 u_short af;
4870 struct peer * p;
4871 l_fp xmt_tx;
4872
4873 DEBUG_REQUIRE(pool);
4874 if (NULL == pool->ai) {
4875 if (pool->addrs != NULL) {
4876 /* free() is used with copy_addrinfo_list() */
4877 free(pool->addrs);
4878 pool->addrs = NULL;
4879 }
4880 af = AF(&pool->srcadr);
4881 if ( (AF_INET == af && !nonlocal_v4_addr_up)
4882 || (AF_INET6 == af && !nonlocal_v6_addr_up)
4883 || ( AF_UNSPEC == af
4884 && !nonlocal_v4_addr_up
4885 && !nonlocal_v6_addr_up)) {
4886
4887 /* POOL DNS query would be useless [Bug 3845] */
4888 return;
4889 }
4890 ZERO(hints);
4891 hints.ai_family = AF(&pool->srcadr);
4892 hints.ai_socktype = SOCK_DGRAM;
4893 hints.ai_protocol = IPPROTO_UDP;
4894 /* ignore getaddrinfo_sometime() errors, we will retry */
4895 rc = getaddrinfo_sometime(
4896 pool->hostname,
4897 "ntp",
4898 &hints,
4899 0, /* no retry */
4900 &pool_name_resolved,
4901 (void *)(intptr_t)pool->associd);
4902 if (!rc)
4903 DPRINTF(1, ("pool DNS lookup %s started\n",
4904 pool->hostname));
4905 else
4906 msyslog(LOG_ERR,
4907 "unable to start pool DNS %s: %m",
4908 pool->hostname);
4909 return;
4910 }
4911
4912 do {
4913 /* copy_addrinfo_list ai_addr points to a sockaddr_u */
4914 rmtadr = (sockaddr_u *)(void *)pool->ai->ai_addr;
4915 pool->ai = pool->ai->ai_next;
4916 /* do not solicit when hopeless [Bug 3845] */
4917 if ( (IS_IPV4(rmtadr) && !nonlocal_v4_addr_up)
4918 || (IS_IPV6(rmtadr) && !nonlocal_v6_addr_up)) {
4919 continue;
4920 }
4921 p = findexistingpeer(rmtadr, NULL, NULL, MODE_CLIENT, 0, NULL);
4922 } while (p != NULL && pool->ai != NULL);
4923 if (p != NULL) {
4924 return; /* out of addresses, re-query DNS next poll */
4925 }
4926 restrict_source(rmtadr, FALSE, 1 + POOL_SOLICIT_WINDOW);
4927 lcladr = findinterface(rmtadr);
4928 memset(&xpkt, 0, sizeof(xpkt));
4929 xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, pool->version,
4930 MODE_CLIENT);
4931 xpkt.stratum = STRATUM_TO_PKT(sys_stratum);
4932 xpkt.ppoll = pool->hpoll;
4933 xpkt.precision = sys_precision;
4934 xpkt.refid = sys_refid;
4935 xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay));
4936 xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp));
4937 /* Bug 3596: What are the pros/cons of using sys_reftime here? */
4938 HTONL_FP(&sys_reftime, &xpkt.reftime);
4939
4940 get_systime(&xmt_tx);
4941 pool->aorg = xmt_tx;
4942
4943 if (FLAG_LOOPNONCE & pool->flags) {
4944 l_fp nonce;
4945
4946 do {
4947 nonce.l_ui = ntp_random();
4948 } while (0 == nonce.l_ui);
4949 do {
4950 nonce.l_uf = ntp_random();
4951 } while (0 == nonce.l_uf);
4952 pool->nonce = nonce;
4953 HTONL_FP(&nonce, &xpkt.xmt);
4954 } else {
4955 L_CLR(&pool->nonce);
4956 HTONL_FP(&xmt_tx, &xpkt.xmt);
4957 }
4958 pool->sent++;
4959 pool->throttle += (1 << pool->minpoll) - 2;
4960 DPRINTF(1, ("pool_xmit: at %ld %s->%s pool\n",
4961 current_time, latoa(lcladr), stoa(rmtadr)));
4962 msyslog(LOG_INFO, "Soliciting pool server %s", stoa(rmtadr));
4963 sendpkt(rmtadr, lcladr,
4964 sys_ttl[(pool->ttl >= sys_ttlmax) ? sys_ttlmax : pool->ttl],
4965 &xpkt, LEN_PKT_NOMAC);
4966 #endif /* WORKER */
4967 }
4968
4969
4970 #ifdef AUTOKEY
4971 /*
4972 * group_test - test if this is the same group
4973 *
4974 * host assoc return action
4975 * none none 0 mobilize *
4976 * none group 0 mobilize *
4977 * group none 0 mobilize *
4978 * group group 1 mobilize
4979 * group different 1 ignore
4980 * * ignore if notrust
4981 */
4982 int
group_test(char * grp,char * ident)4983 group_test(
4984 char *grp,
4985 char *ident
4986 )
4987 {
4988 if (grp == NULL)
4989 return (0);
4990
4991 if (strcmp(grp, sys_groupname) == 0)
4992 return (0);
4993
4994 if (ident == NULL)
4995 return (1);
4996
4997 if (strcmp(grp, ident) == 0)
4998 return (0);
4999
5000 return (1);
5001 }
5002 #endif /* AUTOKEY */
5003
5004
5005 #ifdef WORKER
5006 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)5007 pool_name_resolved(
5008 int rescode,
5009 int gai_errno,
5010 void * context,
5011 const char * name,
5012 const char * service,
5013 const struct addrinfo * hints,
5014 const struct addrinfo * res
5015 )
5016 {
5017 struct peer * pool; /* pool solicitor association */
5018 associd_t assoc;
5019
5020 if (rescode) {
5021 msyslog(LOG_ERR,
5022 "error resolving pool %s: %s (%d)",
5023 name, gai_strerror(rescode), rescode);
5024 return;
5025 }
5026
5027 assoc = (associd_t)(intptr_t)context;
5028 pool = findpeerbyassoc(assoc);
5029 if (NULL == pool) {
5030 msyslog(LOG_ERR,
5031 "Could not find assoc %u for pool DNS %s",
5032 assoc, name);
5033 return;
5034 }
5035 DPRINTF(1, ("pool DNS %s completed\n", name));
5036 pool->addrs = copy_addrinfo_list(res);
5037 pool->ai = pool->addrs;
5038 pool_xmit(pool);
5039
5040 }
5041 #endif /* WORKER */
5042
5043
5044 #ifdef AUTOKEY
5045 /*
5046 * key_expire - purge the key list
5047 */
5048 void
key_expire(struct peer * peer)5049 key_expire(
5050 struct peer *peer /* peer structure pointer */
5051 )
5052 {
5053 int i;
5054
5055 if (peer->keylist != NULL) {
5056 for (i = 0; i <= peer->keynumber; i++)
5057 authtrust(peer->keylist[i], 0);
5058 free(peer->keylist);
5059 peer->keylist = NULL;
5060 }
5061 value_free(&peer->sndval);
5062 peer->keynumber = 0;
5063 peer->flags &= ~FLAG_ASSOC;
5064 DPRINTF(1, ("key_expire: at %lu associd %d\n", current_time,
5065 peer->associd));
5066 }
5067 #endif /* AUTOKEY */
5068
5069
5070 /*
5071 * local_refid(peer) - Check peer refid to avoid selecting peers
5072 * currently synced to this ntpd.
5073 * Note that until 4.2.8p18 and 4.3.1XX ntpd calculated the IPv6
5074 * refid differently on different-endian systems. It now calculates
5075 * the refid the same on both, the same way it did on little-endian
5076 * in the past. On big-endian systems, ntpd also calculates a
5077 * byte-swapped version of each of its IPv6 local addresses' refids,
5078 * as endpt.old_refid and also detects a loop when seeing it. This
5079 * ensures new BE ntpd will detect loops interoperating with older
5080 * BE ntpd, and keeps the more-common LE old ntpd code detecting
5081 * loops with IPv6 refids correctly. Thanks to Hal Murray for
5082 * the byte-swapping idea.
5083 */
5084 static int
local_refid(struct peer * p)5085 local_refid(
5086 struct peer * p
5087 )
5088 {
5089 endpt * unicast_ep;
5090
5091 if (p->dstadr != NULL && !(INT_MCASTIF & p->dstadr->flags))
5092 unicast_ep = p->dstadr;
5093 else
5094 unicast_ep = findinterface(&p->srcadr);
5095
5096 if (unicast_ep != NULL
5097 && ( p->refid == unicast_ep->addr_refid
5098 #ifdef WORDS_BIGENDIAN
5099 || ( IS_IPV6(&unicast_ep->sin)
5100 && p->refid == unicast_ep->old_refid)
5101 #endif
5102 )) {
5103 return TRUE;
5104 } else {
5105 return FALSE;
5106 }
5107 }
5108
5109
5110 /*
5111 * Determine if the peer is unfit for synchronization
5112 *
5113 * A peer is unfit for synchronization if
5114 * > TEST10 bad leap or stratum below floor or at or above ceiling
5115 * > TEST11 root distance exceeded for remote peer
5116 * > TEST12 a direct or indirect synchronization loop would form
5117 * > TEST13 unreachable or noselect
5118 */
5119 int /* FALSE if fit, TRUE if unfit */
peer_unfit(struct peer * peer)5120 peer_unfit(
5121 struct peer *peer /* peer structure pointer */
5122 )
5123 {
5124 int rval = 0;
5125
5126 /*
5127 * A stratum error occurs if (1) the server has never been
5128 * synchronized, (2) the server stratum is below the floor or
5129 * greater than or equal to the ceiling.
5130 */
5131 if ( peer->leap == LEAP_NOTINSYNC
5132 || peer->stratum < sys_floor
5133 || peer->stratum >= sys_ceiling) {
5134 rval |= TEST10; /* bad synch or stratum */
5135 }
5136
5137 /*
5138 * A distance error for a remote peer occurs if the root
5139 * distance is greater than or equal to the distance threshold
5140 * plus the increment due to one host poll interval.
5141 */
5142 if ( !(peer->flags & FLAG_REFCLOCK)
5143 && root_distance(peer) >= sys_maxdist
5144 + clock_phi * ULOGTOD(peer->hpoll)) {
5145 rval |= TEST11; /* distance exceeded */
5146 }
5147
5148 /*
5149 * A loop error occurs if the remote peer is synchronized to the
5150 * local peer or if the remote peer is synchronized to the same
5151 * server as the local peer but only if the remote peer is
5152 * neither a reference clock nor an orphan.
5153 */
5154 if (peer->stratum > 1 && local_refid(peer)) {
5155 rval |= TEST12; /* synchronization loop */
5156 }
5157
5158 /*
5159 * An unreachable error occurs if the server is unreachable or
5160 * the noselect bit is set.
5161 */
5162 if (!peer->reach || (peer->flags & FLAG_NOSELECT)) {
5163 rval |= TEST13; /* unreachable */
5164 }
5165
5166 peer->flash &= ~PEER_TEST_MASK;
5167 peer->flash |= rval;
5168 return (rval);
5169 }
5170
5171
5172 /*
5173 * Find the precision of this particular machine
5174 */
5175 #define MINSTEP 20e-9 /* minimum clock increment (s) */
5176 #define MAXSTEP 1 /* maximum clock increment (s) */
5177 #define MINCHANGES 12 /* minimum number of step samples */
5178 #define MAXLOOPS ((int)(1. / MINSTEP)) /* avoid infinite loop */
5179
5180 /*
5181 * This routine measures the system precision defined as the minimum of
5182 * a sequence of differences between successive readings of the system
5183 * clock. However, if a difference is less than MINSTEP, the clock has
5184 * been read more than once during a clock tick and the difference is
5185 * ignored. We set MINSTEP greater than zero in case something happens
5186 * like a cache miss, and to tolerate underlying system clocks which
5187 * ensure each reading is strictly greater than prior readings while
5188 * using an underlying stepping (not interpolated) clock.
5189 *
5190 * sys_tick and sys_precision represent the time to read the clock for
5191 * systems with high-precision clocks, and the tick interval or step
5192 * size for lower-precision stepping clocks.
5193 *
5194 * This routine also measures the time to read the clock on stepping
5195 * system clocks by counting the number of readings between changes of
5196 * the underlying clock. With either type of clock, the minimum time
5197 * to read the clock is saved as sys_fuzz, and used to ensure the
5198 * get_systime() readings always increase and are fuzzed below sys_fuzz.
5199 */
5200 void
measure_precision(void)5201 measure_precision(void)
5202 {
5203 /*
5204 * With sys_fuzz set to zero, get_systime() fuzzing of low bits
5205 * is effectively disabled. trunc_os_clock is FALSE to disable
5206 * get_ostime() simulation of a low-precision system clock.
5207 */
5208 set_sys_fuzz(0.);
5209 trunc_os_clock = FALSE;
5210 measured_tick = measure_tick_fuzz();
5211 set_sys_tick_precision(measured_tick);
5212 msyslog(LOG_INFO, "proto: precision = %.3f usec (%d)",
5213 sys_tick * 1e6, sys_precision);
5214 if (sys_fuzz < sys_tick) {
5215 msyslog(LOG_NOTICE, "proto: fuzz beneath %.3f usec",
5216 sys_fuzz * 1e6);
5217 }
5218 }
5219
5220
5221 /*
5222 * measure_tick_fuzz()
5223 *
5224 * measures the minimum time to read the clock (stored in sys_fuzz)
5225 * and returns the tick, the larger of the minimum increment observed
5226 * between successive clock readings and the time to read the clock.
5227 */
5228 double
measure_tick_fuzz(void)5229 measure_tick_fuzz(void)
5230 {
5231 l_fp minstep; /* MINSTEP as l_fp */
5232 l_fp val; /* current seconds fraction */
5233 l_fp last; /* last seconds fraction */
5234 l_fp ldiff; /* val - last */
5235 double tick; /* computed tick value */
5236 double diff;
5237 long repeats;
5238 long max_repeats;
5239 int changes;
5240 int i; /* log2 precision */
5241
5242 tick = MAXSTEP;
5243 max_repeats = 0;
5244 repeats = 0;
5245 changes = 0;
5246 DTOLFP(MINSTEP, &minstep);
5247 get_systime(&last);
5248 for (i = 0; i < MAXLOOPS && changes < MINCHANGES; i++) {
5249 get_systime(&val);
5250 ldiff = val;
5251 L_SUB(&ldiff, &last);
5252 last = val;
5253 if (L_ISGT(&ldiff, &minstep)) {
5254 max_repeats = max(repeats, max_repeats);
5255 repeats = 0;
5256 changes++;
5257 LFPTOD(&ldiff, diff);
5258 tick = min(diff, tick);
5259 } else {
5260 repeats++;
5261 }
5262 }
5263 if (changes < MINCHANGES) {
5264 msyslog(LOG_ERR, "Fatal error: precision could not be measured (MINSTEP too large?)");
5265 exit(1);
5266 }
5267
5268 if (0 == max_repeats) {
5269 set_sys_fuzz(tick);
5270 } else {
5271 set_sys_fuzz(tick / max_repeats);
5272 }
5273
5274 return tick;
5275 }
5276
5277
5278 void
set_sys_tick_precision(double tick)5279 set_sys_tick_precision(
5280 double tick
5281 )
5282 {
5283 int i;
5284
5285 if (tick > 1.) {
5286 msyslog(LOG_ERR,
5287 "unsupported tick %.3f > 1s ignored", tick);
5288 return;
5289 }
5290 if (tick < measured_tick) {
5291 msyslog(LOG_ERR,
5292 "proto: tick %.3f less than measured tick %.3f, ignored",
5293 tick, measured_tick);
5294 return;
5295 } else if (tick > measured_tick) {
5296 trunc_os_clock = TRUE;
5297 msyslog(LOG_NOTICE,
5298 "proto: truncating system clock to multiples of %.9f",
5299 tick);
5300 }
5301 sys_tick = tick;
5302
5303 /*
5304 * Find the nearest power of two.
5305 */
5306 for (i = 0; tick <= 1; i--)
5307 tick *= 2;
5308 if (tick - 1 > 1 - tick / 2)
5309 i++;
5310
5311 sys_precision = (s_char)i;
5312 }
5313
5314
5315 /*
5316 * init_proto - initialize the protocol module's data
5317 */
5318 void
init_proto(void)5319 init_proto(void)
5320 {
5321 l_fp dummy;
5322 int i;
5323
5324 /*
5325 * Fill in the sys_* stuff. Default is don't listen to
5326 * broadcasting, require authentication.
5327 */
5328 set_sys_leap(LEAP_NOTINSYNC);
5329 sys_stratum = STRATUM_UNSPEC;
5330 memcpy(&sys_refid, "INIT", 4);
5331 sys_peer = NULL;
5332 sys_rootdelay = 0;
5333 sys_rootdisp = 0;
5334 L_CLR(&sys_reftime);
5335 sys_jitter = 0;
5336 measure_precision();
5337 get_systime(&dummy);
5338 sys_survivors = 0;
5339 sys_manycastserver = 0;
5340 sys_bclient = 0;
5341 sys_mclient = 0;
5342 sys_bdelay = BDELAY_DEFAULT; /*[Bug 3031] delay cutoff */
5343 sys_authenticate = 1;
5344 sys_stattime = current_time;
5345 orphwait = current_time + sys_orphwait;
5346 proto_clr_stats();
5347 for (i = 0; i < MAX_TTL; ++i)
5348 sys_ttl[i] = (u_char)((i * 256) / MAX_TTL);
5349 sys_ttlmax = (MAX_TTL - 1);
5350 hardpps_enable = 0;
5351 stats_control = 1;
5352 }
5353
5354
5355 /*
5356 * proto_config - configure the protocol module
5357 */
5358 void
proto_config(int item,u_long value,double dvalue,sockaddr_u * svalue)5359 proto_config(
5360 int item,
5361 u_long value,
5362 double dvalue,
5363 sockaddr_u *svalue
5364 )
5365 {
5366 /*
5367 * Figure out what he wants to change, then do it
5368 */
5369 DPRINTF(2, ("proto_config: code %d value %lu dvalue %lf\n",
5370 item, value, dvalue));
5371
5372 switch (item) {
5373
5374 /*
5375 * enable and disable commands - arguments are Boolean.
5376 */
5377 case PROTO_AUTHENTICATE: /* authentication (auth) */
5378 sys_authenticate = value;
5379 break;
5380
5381 case PROTO_BROADCLIENT: /* broadcast client (bclient) */
5382 sys_bclient = (int)value;
5383 if (!sys_bclient)
5384 io_unsetbclient();
5385 else
5386 io_setbclient();
5387 break;
5388
5389 #ifdef REFCLOCK
5390 case PROTO_CAL: /* refclock calibrate (calibrate) */
5391 cal_enable = value;
5392 break;
5393 #endif /* REFCLOCK */
5394
5395 case PROTO_KERNEL: /* kernel discipline (kernel) */
5396 select_loop(value);
5397 break;
5398
5399 case PROTO_MONITOR: /* monitoring (monitor) */
5400 if (value)
5401 mon_start(MON_ON);
5402 else {
5403 mon_stop(MON_ON);
5404 if (mon_enabled)
5405 msyslog(LOG_WARNING,
5406 "restrict: 'monitor' cannot be disabled while 'limited' is enabled");
5407 }
5408 break;
5409
5410 case PROTO_NTP: /* NTP discipline (ntp) */
5411 ntp_enable = value;
5412 break;
5413
5414 case PROTO_MODE7: /* mode7 management (ntpdc) */
5415 ntp_mode7 = value;
5416 break;
5417
5418 case PROTO_PPS: /* PPS discipline (pps) */
5419 hardpps_enable = value;
5420 break;
5421
5422 case PROTO_FILEGEN: /* statistics (stats) */
5423 stats_control = value;
5424 break;
5425
5426 /*
5427 * tos command - arguments are double, sometimes cast to int
5428 */
5429
5430 case PROTO_BCPOLLBSTEP: /* Broadcast Poll Backstep gate (bcpollbstep) */
5431 sys_bcpollbstep = (u_char)dvalue;
5432 break;
5433
5434 case PROTO_BEACON: /* manycast beacon (beacon) */
5435 sys_beacon = (int)dvalue;
5436 break;
5437
5438 case PROTO_BROADDELAY: /* default broadcast delay (bdelay) */
5439 sys_bdelay = (dvalue ? dvalue : BDELAY_DEFAULT);
5440 break;
5441
5442 case PROTO_CEILING: /* stratum ceiling (ceiling) */
5443 sys_ceiling = (int)dvalue;
5444 break;
5445
5446 case PROTO_COHORT: /* cohort switch (cohort) */
5447 sys_cohort = (int)dvalue;
5448 break;
5449
5450 case PROTO_FLOOR: /* stratum floor (floor) */
5451 sys_floor = (int)dvalue;
5452 break;
5453
5454 case PROTO_MAXCLOCK: /* maximum candidates (maxclock) */
5455 sys_maxclock = (int)dvalue;
5456 break;
5457
5458 case PROTO_MAXDIST: /* select threshold (maxdist) */
5459 sys_maxdist = dvalue;
5460 break;
5461
5462 case PROTO_CALLDELAY: /* modem call delay (mdelay) */
5463 break; /* NOT USED */
5464
5465 case PROTO_MINCLOCK: /* minimum candidates (minclock) */
5466 sys_minclock = (int)dvalue;
5467 break;
5468
5469 case PROTO_MINDISP: /* minimum distance (mindist) */
5470 sys_mindisp = dvalue;
5471 break;
5472
5473 case PROTO_MINSANE: /* minimum survivors (minsane) */
5474 sys_minsane = (int)dvalue;
5475 break;
5476
5477 case PROTO_ORPHAN: /* orphan stratum (orphan) */
5478 sys_orphan = (int)dvalue;
5479 break;
5480
5481 case PROTO_ORPHWAIT: /* orphan wait (orphwait) */
5482 orphwait -= sys_orphwait;
5483 sys_orphwait = (dvalue >= 1) ? (int)dvalue : NTP_ORPHWAIT;
5484 orphwait += sys_orphwait;
5485 break;
5486
5487 /*
5488 * Miscellaneous commands
5489 */
5490 case PROTO_MULTICAST_ADD: /* add group address */
5491 if (svalue != NULL)
5492 io_multicast_add(svalue);
5493 sys_mclient = 1;
5494 break;
5495
5496 case PROTO_MULTICAST_DEL: /* delete group address */
5497 if (svalue != NULL)
5498 io_multicast_del(svalue);
5499 break;
5500
5501 /*
5502 * Peer_clear Early policy choices
5503 */
5504
5505 case PROTO_PCEDIGEST: /* Digest */
5506 peer_clear_digest_early = value;
5507 break;
5508
5509 /*
5510 * Unpeer Early policy choices
5511 */
5512
5513 case PROTO_UECRYPTO: /* Crypto */
5514 unpeer_crypto_early = value;
5515 break;
5516
5517 case PROTO_UECRYPTONAK: /* Crypto_NAK */
5518 unpeer_crypto_nak_early = value;
5519 break;
5520
5521 case PROTO_UEDIGEST: /* Digest */
5522 unpeer_digest_early = value;
5523 break;
5524
5525 default:
5526 msyslog(LOG_NOTICE,
5527 "proto: unsupported option %d", item);
5528 }
5529 }
5530
5531
5532 /*
5533 * proto_clr_stats - clear protocol stat counters
5534 */
5535 void
proto_clr_stats(void)5536 proto_clr_stats(void)
5537 {
5538 sys_stattime = current_time;
5539 sys_received = 0;
5540 sys_processed = 0;
5541 sys_newversion = 0;
5542 sys_oldversion = 0;
5543 sys_declined = 0;
5544 sys_restricted = 0;
5545 sys_badlength = 0;
5546 sys_badauth = 0;
5547 sys_limitrejected = 0;
5548 sys_kodsent = 0;
5549 sys_lamport = 0;
5550 sys_tsrounding = 0;
5551 }
5552