2 * NTP client/server, based on OpenNTPD 3.9p1
4 * Author: Adam Tkac <vonsch@gmail.com>
6 * Licensed under GPLv2, see file LICENSE in this source tree.
8 * Parts of OpenNTPD clock syncronization code is replaced by
9 * code which is based on ntp-4.2.6, whuch carries the following
12 ***********************************************************************
14 * Copyright (c) University of Delaware 1992-2009 *
16 * Permission to use, copy, modify, and distribute this software and *
17 * its documentation for any purpose with or without fee is hereby *
18 * granted, provided that the above copyright notice appears in all *
19 * copies and that both the copyright notice and this permission *
20 * notice appear in supporting documentation, and that the name *
21 * University of Delaware not be used in advertising or publicity *
22 * pertaining to distribution of the software without specific, *
23 * written prior permission. The University of Delaware makes no *
24 * representations about the suitability this software for any *
25 * purpose. It is provided "as is" without express or implied *
28 ***********************************************************************
31 //usage:#define ntpd_trivial_usage
32 //usage: "[-dnqNw"IF_FEATURE_NTPD_SERVER("l")"] [-S PROG] [-p PEER]..."
33 //usage:#define ntpd_full_usage "\n\n"
34 //usage: "NTP client/server\n"
35 //usage: "\n -d Verbose"
36 //usage: "\n -n Do not daemonize"
37 //usage: "\n -q Quit after clock is set"
38 //usage: "\n -N Run at high priority"
39 //usage: "\n -w Do not set time (only query peers), implies -n"
40 //usage: IF_FEATURE_NTPD_SERVER(
41 //usage: "\n -l Run as server on port 123"
43 //usage: "\n -S PROG Run PROG after stepping time, stratum change, and every 11 mins"
44 //usage: "\n -p PEER Obtain time from PEER (may be repeated)"
48 #include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
49 #include <sys/timex.h>
50 #ifndef IPTOS_LOWDELAY
51 # define IPTOS_LOWDELAY 0x10
54 # error "Sorry, your kernel has to support IP_PKTINFO"
58 /* Verbosity control (max level of -dddd options accepted).
59 * max 5 is very talkative (and bloated). 2 is non-bloated,
60 * production level setting.
65 /* High-level description of the algorithm:
67 * We start running with very small poll_exp, BURSTPOLL,
68 * in order to quickly accumulate INITIAL_SAMPLES datapoints
69 * for each peer. Then, time is stepped if the offset is larger
70 * than STEP_THRESHOLD, otherwise it isn't; anyway, we enlarge
71 * poll_exp to MINPOLL and enter frequency measurement step:
72 * we collect new datapoints but ignore them for WATCH_THRESHOLD
73 * seconds. After WATCH_THRESHOLD seconds we look at accumulated
74 * offset and estimate frequency drift.
76 * (frequency measurement step seems to not be strictly needed,
77 * it is conditionally disabled with USING_INITIAL_FREQ_ESTIMATION
80 * After this, we enter "steady state": we collect a datapoint,
81 * we select the best peer, if this datapoint is not a new one
82 * (IOW: if this datapoint isn't for selected peer), sleep
83 * and collect another one; otherwise, use its offset to update
84 * frequency drift, if offset is somewhat large, reduce poll_exp,
85 * otherwise increase poll_exp.
87 * If offset is larger than STEP_THRESHOLD, which shouldn't normally
88 * happen, we assume that something "bad" happened (computer
89 * was hibernated, someone set totally wrong date, etc),
90 * then the time is stepped, all datapoints are discarded,
91 * and we go back to steady state.
94 #define RETRY_INTERVAL 5 /* on error, retry in N secs */
95 #define RESPONSE_INTERVAL 15 /* wait for reply up to N secs */
96 #define INITIAL_SAMPLES 4 /* how many samples do we want for init */
98 /* Clock discipline parameters and constants */
100 /* Step threshold (sec). std ntpd uses 0.128.
101 * Using exact power of 2 (1/8) results in smaller code */
102 #define STEP_THRESHOLD 0.125
103 #define WATCH_THRESHOLD 128 /* stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */
104 /* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */
105 //UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */
107 #define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */
108 #define BURSTPOLL 0 /* initial poll */
109 #define MINPOLL 5 /* minimum poll interval. std ntpd uses 6 (6: 64 sec) */
110 /* If offset > discipline_jitter * POLLADJ_GATE, and poll interval is >= 2^BIGPOLL,
111 * then it is decreased _at once_. (If < 2^BIGPOLL, it will be decreased _eventually_).
113 #define BIGPOLL 10 /* 2^10 sec ~= 17 min */
114 #define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h). std ntpd uses 17 */
115 /* Actively lower poll when we see such big offsets.
116 * With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively
117 * if offset increases over ~0.04 sec */
118 #define POLLDOWN_OFFSET (STEP_THRESHOLD / 3)
119 #define MINDISP 0.01 /* minimum dispersion (sec) */
120 #define MAXDISP 16 /* maximum dispersion (sec) */
121 #define MAXSTRAT 16 /* maximum stratum (infinity metric) */
122 #define MAXDIST 1 /* distance threshold (sec) */
123 #define MIN_SELECTED 1 /* minimum intersection survivors */
124 #define MIN_CLUSTERED 3 /* minimum cluster survivors */
126 #define MAXDRIFT 0.000500 /* frequency drift we can correct (500 PPM) */
128 /* Poll-adjust threshold.
129 * When we see that offset is small enough compared to discipline jitter,
130 * we grow a counter: += MINPOLL. When counter goes over POLLADJ_LIMIT,
131 * we poll_exp++. If offset isn't small, counter -= poll_exp*2,
132 * and when it goes below -POLLADJ_LIMIT, we poll_exp--.
133 * (Bumped from 30 to 40 since otherwise I often see poll_exp going *2* steps down)
135 #define POLLADJ_LIMIT 40
136 /* If offset < discipline_jitter * POLLADJ_GATE, then we decide to increase
137 * poll interval (we think we can't improve timekeeping
138 * by staying at smaller poll).
140 #define POLLADJ_GATE 4
141 #define TIMECONST_HACK_GATE 2
142 /* Compromise Allan intercept (sec). doc uses 1500, std ntpd uses 512 */
146 /* FLL loop gain [why it depends on MAXPOLL??] */
147 #define FLL (MAXPOLL + 1)
148 /* Parameter averaging constant */
157 NTP_MSGSIZE_NOAUTH = 48,
158 NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
161 MODE_MASK = (7 << 0),
162 VERSION_MASK = (7 << 3),
166 /* Leap Second Codes (high order two bits of m_status) */
167 LI_NOWARNING = (0 << 6), /* no warning */
168 LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
169 LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
170 LI_ALARM = (3 << 6), /* alarm condition */
173 MODE_RES0 = 0, /* reserved */
174 MODE_SYM_ACT = 1, /* symmetric active */
175 MODE_SYM_PAS = 2, /* symmetric passive */
176 MODE_CLIENT = 3, /* client */
177 MODE_SERVER = 4, /* server */
178 MODE_BROADCAST = 5, /* broadcast */
179 MODE_RES1 = 6, /* reserved for NTP control message */
180 MODE_RES2 = 7, /* reserved for private use */
183 //TODO: better base selection
184 #define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
186 #define NUM_DATAPOINTS 8
199 uint8_t m_status; /* status of local clock and leap info */
201 uint8_t m_ppoll; /* poll value */
202 int8_t m_precision_exp;
203 s_fixedpt_t m_rootdelay;
204 s_fixedpt_t m_rootdisp;
206 l_fixedpt_t m_reftime;
207 l_fixedpt_t m_orgtime;
208 l_fixedpt_t m_rectime;
209 l_fixedpt_t m_xmttime;
211 uint8_t m_digest[NTP_DIGESTSIZE];
221 len_and_sockaddr *p_lsa;
225 uint32_t lastpkt_refid;
226 uint8_t lastpkt_status;
227 uint8_t lastpkt_stratum;
228 uint8_t reachable_bits;
229 /* when to send new query (if p_fd == -1)
230 * or when receive times out (if p_fd >= 0): */
231 double next_action_time;
233 double lastpkt_recv_time;
234 double lastpkt_delay;
235 double lastpkt_rootdelay;
236 double lastpkt_rootdisp;
237 /* produced by filter algorithm: */
238 double filter_offset;
239 double filter_dispersion;
240 double filter_jitter;
241 datapoint_t filter_datapoint[NUM_DATAPOINTS];
242 /* last sent packet: */
247 #define USING_KERNEL_PLL_LOOP 1
248 #define USING_INITIAL_FREQ_ESTIMATION 0
255 /* Insert new options above this line. */
256 /* Non-compat options: */
260 OPT_l = (1 << 7) * ENABLE_FEATURE_NTPD_SERVER,
261 /* We hijack some bits for other purposes */
267 /* total round trip delay to currently selected reference clock */
269 /* reference timestamp: time when the system clock was last set or corrected */
271 /* total dispersion to currently selected reference clock */
274 double last_script_run;
277 #if ENABLE_FEATURE_NTPD_SERVER
279 # define G_listen_fd (G.listen_fd)
281 # define G_listen_fd (-1)
285 /* refid: 32-bit code identifying the particular server or reference clock
286 * in stratum 0 packets this is a four-character ASCII string,
287 * called the kiss code, used for debugging and monitoring
288 * in stratum 1 packets this is a four-character ASCII string
289 * assigned to the reference clock by IANA. Example: "GPS "
290 * in stratum 2+ packets, it's IPv4 address or 4 first bytes
291 * of MD5 hash of IPv6
295 /* precision is defined as the larger of the resolution and time to
296 * read the clock, in log2 units. For instance, the precision of a
297 * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
298 * system clock hardware representation is to the nanosecond.
300 * Delays, jitters of various kinds are clamped down to precision.
302 * If precision_sec is too large, discipline_jitter gets clamped to it
303 * and if offset is smaller than discipline_jitter * POLLADJ_GATE, poll
304 * interval grows even though we really can benefit from staying at
305 * smaller one, collecting non-lagged datapoits and correcting offset.
306 * (Lagged datapoits exist when poll_exp is large but we still have
307 * systematic offset error - the time distance between datapoints
308 * is significant and older datapoints have smaller offsets.
309 * This makes our offset estimation a bit smaller than reality)
310 * Due to this effect, setting G_precision_sec close to
311 * STEP_THRESHOLD isn't such a good idea - offsets may grow
312 * too big and we will step. I observed it with -6.
314 * OTOH, setting precision_sec far too small would result in futile
315 * attempts to syncronize to an unachievable precision.
317 * -6 is 1/64 sec, -7 is 1/128 sec and so on.
318 * -8 is 1/256 ~= 0.003906 (worked well for me --vda)
319 * -9 is 1/512 ~= 0.001953 (let's try this for some time)
321 #define G_precision_exp -9
323 * G_precision_exp is used only for construction outgoing packets.
324 * It's ok to set G_precision_sec to a slightly different value
325 * (One which is "nicer looking" in logs).
326 * Exact value would be (1.0 / (1 << (- G_precision_exp))):
328 #define G_precision_sec 0.002
330 /* Bool. After set to 1, never goes back to 0: */
331 smallint initial_poll_complete;
333 #define STATE_NSET 0 /* initial state, "nothing is set" */
334 //#define STATE_FSET 1 /* frequency set from file */
335 #define STATE_SPIK 2 /* spike detected */
336 //#define STATE_FREQ 3 /* initial frequency */
337 #define STATE_SYNC 4 /* clock synchronized (normal operation) */
338 uint8_t discipline_state; // doc calls it c.state
339 uint8_t poll_exp; // s.poll
340 int polladj_count; // c.count
341 long kernel_freq_drift;
342 peer_t *last_update_peer;
343 double last_update_offset; // c.last
344 double last_update_recv_time; // s.t
345 double discipline_jitter; // c.jitter
346 /* Since we only compare it with ints, can simplify code
347 * by not making this variable floating point:
349 unsigned offset_to_jitter_ratio;
350 //double cluster_offset; // s.offset
351 //double cluster_jitter; // s.jitter
352 #if !USING_KERNEL_PLL_LOOP
353 double discipline_freq_drift; // c.freq
354 /* Maybe conditionally calculate wander? it's used only for logging */
355 double discipline_wander; // c.wander
358 #define G (*ptr_to_globals)
360 static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
363 #define VERB1 if (MAX_VERBOSE && G.verbose)
364 #define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
365 #define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
366 #define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
367 #define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
370 static double LOG2D(int a)
373 return 1.0 / (1UL << -a);
376 static ALWAYS_INLINE double SQUARE(double x)
380 static ALWAYS_INLINE double MAXD(double a, double b)
386 static ALWAYS_INLINE double MIND(double a, double b)
392 static NOINLINE double my_SQRT(double X)
399 double Xhalf = X * 0.5;
401 /* Fast and good approximation to 1/sqrt(X), black magic */
403 /*v.i = 0x5f3759df - (v.i >> 1);*/
404 v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
405 invsqrt = v.f; /* better than 0.2% accuracy */
407 /* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
408 * f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
410 * f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
411 * x1 = x0 - (X*x0*x0*x0/2 - x0/2) = 1.5*x0 - X*x0*x0*x0/2 = x0*(1.5 - (X/2)*x0*x0)
413 invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
414 /* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
415 /* With 4 iterations, more than half results will be exact,
416 * at 6th iterations result stabilizes with about 72% results exact.
417 * We are well satisfied with 0.05% accuracy.
420 return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
422 static ALWAYS_INLINE double SQRT(double X)
424 /* If this arch doesn't use IEEE 754 floats, fall back to using libm */
425 if (sizeof(float) != 4)
428 /* This avoids needing libm, saves about 0.5k on x86-32 */
436 gettimeofday(&tv, NULL); /* never fails */
437 G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
442 d_to_tv(double d, struct timeval *tv)
444 tv->tv_sec = (long)d;
445 tv->tv_usec = (d - tv->tv_sec) * 1000000;
449 lfp_to_d(l_fixedpt_t lfp)
452 lfp.int_partl = ntohl(lfp.int_partl);
453 lfp.fractionl = ntohl(lfp.fractionl);
454 ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
458 sfp_to_d(s_fixedpt_t sfp)
461 sfp.int_parts = ntohs(sfp.int_parts);
462 sfp.fractions = ntohs(sfp.fractions);
463 ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
466 #if ENABLE_FEATURE_NTPD_SERVER
471 lfp.int_partl = (uint32_t)d;
472 lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
473 lfp.int_partl = htonl(lfp.int_partl);
474 lfp.fractionl = htonl(lfp.fractionl);
481 sfp.int_parts = (uint16_t)d;
482 sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
483 sfp.int_parts = htons(sfp.int_parts);
484 sfp.fractions = htons(sfp.fractions);
490 dispersion(const datapoint_t *dp)
492 return dp->d_dispersion + FREQ_TOLERANCE * (G.cur_time - dp->d_recv_time);
496 root_distance(peer_t *p)
498 /* The root synchronization distance is the maximum error due to
499 * all causes of the local clock relative to the primary server.
500 * It is defined as half the total delay plus total dispersion
503 return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2
504 + p->lastpkt_rootdisp
505 + p->filter_dispersion
506 + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time)
511 set_next(peer_t *p, unsigned t)
513 p->next_action_time = G.cur_time + t;
517 * Peer clock filter and its helpers
520 filter_datapoints(peer_t *p)
527 /* Simulations have shown that use of *averaged* offset for p->filter_offset
528 * is in fact worse than simply using last received one: with large poll intervals
529 * (>= 2048) averaging code uses offset values which are outdated by hours,
530 * and time/frequency correction goes totally wrong when fed essentially bogus offsets.
533 double minoff, maxoff, w;
534 double x = x; /* for compiler */
535 double oldest_off = oldest_off;
536 double oldest_age = oldest_age;
537 double newest_off = newest_off;
538 double newest_age = newest_age;
540 fdp = p->filter_datapoint;
542 minoff = maxoff = fdp[0].d_offset;
543 for (i = 1; i < NUM_DATAPOINTS; i++) {
544 if (minoff > fdp[i].d_offset)
545 minoff = fdp[i].d_offset;
546 if (maxoff < fdp[i].d_offset)
547 maxoff = fdp[i].d_offset;
550 idx = p->datapoint_idx; /* most recent datapoint's index */
552 * Drop two outliers and take weighted average of the rest:
553 * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
554 * we use older6/32, not older6/64 since sum of weights should be 1:
555 * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
561 * filter_dispersion = \ -------------
568 for (i = 0; i < NUM_DATAPOINTS; i++) {
570 bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
573 fdp[idx].d_dispersion, dispersion(&fdp[idx]),
574 G.cur_time - fdp[idx].d_recv_time,
575 (minoff == fdp[idx].d_offset || maxoff == fdp[idx].d_offset)
576 ? " (outlier by offset)" : ""
580 sum += dispersion(&fdp[idx]) / (2 << i);
582 if (minoff == fdp[idx].d_offset) {
583 minoff -= 1; /* so that we don't match it ever again */
585 if (maxoff == fdp[idx].d_offset) {
588 oldest_off = fdp[idx].d_offset;
589 oldest_age = G.cur_time - fdp[idx].d_recv_time;
592 newest_off = oldest_off;
593 newest_age = oldest_age;
600 idx = (idx - 1) & (NUM_DATAPOINTS - 1);
602 p->filter_dispersion = sum;
603 wavg += x; /* add another older6/64 to form older6/32 */
604 /* Fix systematic underestimation with large poll intervals.
605 * Imagine that we still have a bit of uncorrected drift,
606 * and poll interval is big (say, 100 sec). Offsets form a progression:
607 * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
608 * The algorithm above drops 0.0 and 0.7 as outliers,
609 * and then we have this estimation, ~25% off from 0.7:
610 * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
612 x = oldest_age - newest_age;
614 x = newest_age / x; /* in above example, 100 / (600 - 100) */
615 if (x < 1) { /* paranoia check */
616 x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
620 p->filter_offset = wavg;
624 fdp = p->filter_datapoint;
625 idx = p->datapoint_idx; /* most recent datapoint's index */
627 /* filter_offset: simply use the most recent value */
628 p->filter_offset = fdp[idx].d_offset;
632 * filter_dispersion = \ -------------
639 for (i = 0; i < NUM_DATAPOINTS; i++) {
640 sum += dispersion(&fdp[idx]) / (2 << i);
641 wavg += fdp[idx].d_offset;
642 idx = (idx - 1) & (NUM_DATAPOINTS - 1);
644 wavg /= NUM_DATAPOINTS;
645 p->filter_dispersion = sum;
648 /* +----- -----+ ^ 1/2
652 * filter_jitter = | --- * / (avg-offset_j) |
656 * where n is the number of valid datapoints in the filter (n > 1);
657 * if filter_jitter < precision then filter_jitter = precision
660 for (i = 0; i < NUM_DATAPOINTS; i++) {
661 sum += SQUARE(wavg - fdp[i].d_offset);
663 sum = SQRT(sum / NUM_DATAPOINTS);
664 p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
666 VERB3 bb_error_msg("filter offset:%+f disp:%f jitter:%f",
668 p->filter_dispersion,
673 reset_peer_stats(peer_t *p, double offset)
676 bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
678 for (i = 0; i < NUM_DATAPOINTS; i++) {
680 p->filter_datapoint[i].d_recv_time += offset;
681 if (p->filter_datapoint[i].d_offset != 0) {
682 p->filter_datapoint[i].d_offset -= offset;
683 //bb_error_msg("p->filter_datapoint[%d].d_offset %f -> %f",
685 // p->filter_datapoint[i].d_offset + offset,
686 // p->filter_datapoint[i].d_offset);
689 p->filter_datapoint[i].d_recv_time = G.cur_time;
690 p->filter_datapoint[i].d_offset = 0;
691 p->filter_datapoint[i].d_dispersion = MAXDISP;
695 p->lastpkt_recv_time += offset;
697 p->reachable_bits = 0;
698 p->lastpkt_recv_time = G.cur_time;
700 filter_datapoints(p); /* recalc p->filter_xxx */
701 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
709 p = xzalloc(sizeof(*p));
710 p->p_lsa = xhost2sockaddr(s, 123);
711 p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
713 p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
714 p->next_action_time = G.cur_time; /* = set_next(p, 0); */
715 reset_peer_stats(p, 16 * STEP_THRESHOLD);
717 llist_add_to(&G.ntp_peers, p);
723 const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
724 msg_t *msg, ssize_t len)
730 ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
732 ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
735 bb_perror_msg("send failed");
742 send_query_to_peer(peer_t *p)
744 /* Why do we need to bind()?
745 * See what happens when we don't bind:
747 * socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
748 * setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
749 * gettimeofday({1259071266, 327885}, NULL) = 0
750 * sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
751 * ^^^ we sent it from some source port picked by kernel.
752 * time(NULL) = 1259071266
753 * write(2, "ntpd: entering poll 15 secs\n", 28) = 28
754 * poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
755 * recv(3, "yyy", 68, MSG_DONTWAIT) = 48
756 * ^^^ this recv will receive packets to any local port!
758 * Uncomment this and use strace to see it in action:
760 #define PROBE_LOCAL_ADDR /* { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } */
764 len_and_sockaddr *local_lsa;
766 family = p->p_lsa->u.sa.sa_family;
767 p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
768 /* local_lsa has "null" address and port 0 now.
769 * bind() ensures we have a *particular port* selected by kernel
770 * and remembered in p->p_fd, thus later recv(p->p_fd)
771 * receives only packets sent to this port.
774 xbind(fd, &local_lsa->u.sa, local_lsa->len);
776 #if ENABLE_FEATURE_IPV6
777 if (family == AF_INET)
779 setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
783 /* Emit message _before_ attempted send. Think of a very short
784 * roundtrip networks: we need to go back to recv loop ASAP,
785 * to reduce delay. Printing messages after send works against that.
787 VERB1 bb_error_msg("sending query to %s", p->p_dotted);
790 * Send out a random 64-bit number as our transmit time. The NTP
791 * server will copy said number into the originate field on the
792 * response that it sends us. This is totally legal per the SNTP spec.
794 * The impact of this is two fold: we no longer send out the current
795 * system time for the world to see (which may aid an attacker), and
796 * it gives us a (not very secure) way of knowing that we're not
797 * getting spoofed by an attacker that can't capture our traffic
798 * but can spoof packets from the NTP server we're communicating with.
800 * Save the real transmit timestamp locally.
802 p->p_xmt_msg.m_xmttime.int_partl = random();
803 p->p_xmt_msg.m_xmttime.fractionl = random();
804 p->p_xmttime = gettime1900d();
806 if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
807 &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
811 set_next(p, RETRY_INTERVAL);
815 p->reachable_bits <<= 1;
816 set_next(p, RESPONSE_INTERVAL);
820 /* Note that there is no provision to prevent several run_scripts
821 * to be done in quick succession. In fact, it happens rather often
822 * if initial syncronization results in a step.
823 * You will see "step" and then "stratum" script runs, sometimes
824 * as close as only 0.002 seconds apart.
825 * Script should be ready to deal with this.
827 static void run_script(const char *action, double offset)
830 char *env1, *env2, *env3, *env4;
835 argv[0] = (char*) G.script_name;
836 argv[1] = (char*) action;
839 VERB1 bb_error_msg("executing '%s %s'", G.script_name, action);
841 env1 = xasprintf("%s=%u", "stratum", G.stratum);
843 env2 = xasprintf("%s=%ld", "freq_drift_ppm", G.kernel_freq_drift);
845 env3 = xasprintf("%s=%u", "poll_interval", 1 << G.poll_exp);
847 env4 = xasprintf("%s=%f", "offset", offset);
849 /* Other items of potential interest: selected peer,
850 * rootdelay, reftime, rootdisp, refid, ntp_status,
851 * last_update_offset, last_update_recv_time, discipline_jitter,
852 * how many peers have reachable_bits = 0?
855 /* Don't want to wait: it may run hwclock --systohc, and that
856 * may take some time (seconds): */
857 /*spawn_and_wait(argv);*/
861 unsetenv("freq_drift_ppm");
862 unsetenv("poll_interval");
869 G.last_script_run = G.cur_time;
873 step_time(double offset)
877 struct timeval tvc, tvn;
878 char buf[sizeof("yyyy-mm-dd hh:mm:ss") + /*paranoia:*/ 4];
881 gettimeofday(&tvc, NULL); /* never fails */
882 dtime = tvc.tv_sec + (1.0e-6 * tvc.tv_usec) + offset;
883 d_to_tv(dtime, &tvn);
884 if (settimeofday(&tvn, NULL) == -1)
885 bb_perror_msg_and_die("settimeofday");
889 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
890 bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
893 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
894 bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
896 /* Correct various fields which contain time-relative values: */
899 G.cur_time += offset;
900 G.last_update_recv_time += offset;
901 G.last_script_run += offset;
903 /* p->lastpkt_recv_time, p->next_action_time and such: */
904 for (item = G.ntp_peers; item != NULL; item = item->link) {
905 peer_t *pp = (peer_t *) item->data;
906 reset_peer_stats(pp, offset);
907 //bb_error_msg("offset:%+f pp->next_action_time:%f -> %f",
908 // offset, pp->next_action_time, pp->next_action_time + offset);
909 pp->next_action_time += offset;
911 /* We wait for reply from this peer too.
912 * But due to step we are doing, reply's data is no longer
913 * useful (in fact, it'll be bogus). Stop waiting for it.
917 set_next(pp, RETRY_INTERVAL);
924 * Selection and clustering, and their helpers
930 double opt_rd; /* optimization */
933 compare_point_edge(const void *aa, const void *bb)
935 const point_t *a = aa;
936 const point_t *b = bb;
937 if (a->edge < b->edge) {
940 return (a->edge > b->edge);
947 compare_survivor_metric(const void *aa, const void *bb)
949 const survivor_t *a = aa;
950 const survivor_t *b = bb;
951 if (a->metric < b->metric) {
954 return (a->metric > b->metric);
957 fit(peer_t *p, double rd)
959 if ((p->reachable_bits & (p->reachable_bits-1)) == 0) {
960 /* One or zero bits in reachable_bits */
961 VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
964 #if 0 /* we filter out such packets earlier */
965 if ((p->lastpkt_status & LI_ALARM) == LI_ALARM
966 || p->lastpkt_stratum >= MAXSTRAT
968 VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
972 /* rd is root_distance(p) */
973 if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
974 VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
978 // /* Do we have a loop? */
979 // if (p->refid == p->dstaddr || p->refid == s.refid)
984 select_and_cluster(void)
989 int size = 3 * G.peer_cnt;
990 /* for selection algorithm */
992 unsigned num_points, num_candidates;
994 unsigned num_falsetickers;
995 /* for cluster algorithm */
996 survivor_t survivor[size];
997 unsigned num_survivors;
1003 if (G.initial_poll_complete) while (item != NULL) {
1006 p = (peer_t *) item->data;
1007 rd = root_distance(p);
1008 offset = p->filter_offset;
1014 VERB4 bb_error_msg("interval: [%f %f %f] %s",
1020 point[num_points].p = p;
1021 point[num_points].type = -1;
1022 point[num_points].edge = offset - rd;
1023 point[num_points].opt_rd = rd;
1025 point[num_points].p = p;
1026 point[num_points].type = 0;
1027 point[num_points].edge = offset;
1028 point[num_points].opt_rd = rd;
1030 point[num_points].p = p;
1031 point[num_points].type = 1;
1032 point[num_points].edge = offset + rd;
1033 point[num_points].opt_rd = rd;
1037 num_candidates = num_points / 3;
1038 if (num_candidates == 0) {
1039 VERB3 bb_error_msg("no valid datapoints, no peer selected");
1042 //TODO: sorting does not seem to be done in reference code
1043 qsort(point, num_points, sizeof(point[0]), compare_point_edge);
1045 /* Start with the assumption that there are no falsetickers.
1046 * Attempt to find a nonempty intersection interval containing
1047 * the midpoints of all truechimers.
1048 * If a nonempty interval cannot be found, increase the number
1049 * of assumed falsetickers by one and try again.
1050 * If a nonempty interval is found and the number of falsetickers
1051 * is less than the number of truechimers, a majority has been found
1052 * and the midpoint of each truechimer represents
1053 * the candidates available to the cluster algorithm.
1055 num_falsetickers = 0;
1058 unsigned num_midpoints = 0;
1063 for (i = 0; i < num_points; i++) {
1065 * if (point[i].type == -1) c++;
1066 * if (point[i].type == 1) c--;
1067 * and it's simpler to do it this way:
1070 if (c >= num_candidates - num_falsetickers) {
1071 /* If it was c++ and it got big enough... */
1072 low = point[i].edge;
1075 if (point[i].type == 0)
1079 for (i = num_points-1; i >= 0; i--) {
1081 if (c >= num_candidates - num_falsetickers) {
1082 high = point[i].edge;
1085 if (point[i].type == 0)
1088 /* If the number of midpoints is greater than the number
1089 * of allowed falsetickers, the intersection contains at
1090 * least one truechimer with no midpoint - bad.
1091 * Also, interval should be nonempty.
1093 if (num_midpoints <= num_falsetickers && low < high)
1096 if (num_falsetickers * 2 >= num_candidates) {
1097 VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected",
1098 num_falsetickers, num_candidates);
1102 VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
1103 low, high, num_candidates, num_falsetickers);
1107 /* Construct a list of survivors (p, metric)
1108 * from the chime list, where metric is dominated
1109 * first by stratum and then by root distance.
1110 * All other things being equal, this is the order of preference.
1113 for (i = 0; i < num_points; i++) {
1114 if (point[i].edge < low || point[i].edge > high)
1117 survivor[num_survivors].p = p;
1118 /* x.opt_rd == root_distance(p); */
1119 survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + point[i].opt_rd;
1120 VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s",
1121 num_survivors, survivor[num_survivors].metric, p->p_dotted);
1124 /* There must be at least MIN_SELECTED survivors to satisfy the
1125 * correctness assertions. Ordinarily, the Byzantine criteria
1126 * require four survivors, but for the demonstration here, one
1129 if (num_survivors < MIN_SELECTED) {
1130 VERB3 bb_error_msg("num_survivors %d < %d, no peer selected",
1131 num_survivors, MIN_SELECTED);
1135 //looks like this is ONLY used by the fact that later we pick survivor[0].
1136 //we can avoid sorting then, just find the minimum once!
1137 qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric);
1139 /* For each association p in turn, calculate the selection
1140 * jitter p->sjitter as the square root of the sum of squares
1141 * (p->offset - q->offset) over all q associations. The idea is
1142 * to repeatedly discard the survivor with maximum selection
1143 * jitter until a termination condition is met.
1146 unsigned max_idx = max_idx;
1147 double max_selection_jitter = max_selection_jitter;
1148 double min_jitter = min_jitter;
1150 if (num_survivors <= MIN_CLUSTERED) {
1151 VERB3 bb_error_msg("num_survivors %d <= %d, not discarding more",
1152 num_survivors, MIN_CLUSTERED);
1156 /* To make sure a few survivors are left
1157 * for the clustering algorithm to chew on,
1158 * we stop if the number of survivors
1159 * is less than or equal to MIN_CLUSTERED (3).
1161 for (i = 0; i < num_survivors; i++) {
1162 double selection_jitter_sq;
1165 if (i == 0 || p->filter_jitter < min_jitter)
1166 min_jitter = p->filter_jitter;
1168 selection_jitter_sq = 0;
1169 for (j = 0; j < num_survivors; j++) {
1170 peer_t *q = survivor[j].p;
1171 selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
1173 if (i == 0 || selection_jitter_sq > max_selection_jitter) {
1174 max_selection_jitter = selection_jitter_sq;
1177 VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
1178 i, selection_jitter_sq);
1180 max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
1181 VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
1182 max_idx, max_selection_jitter, min_jitter);
1184 /* If the maximum selection jitter is less than the
1185 * minimum peer jitter, then tossing out more survivors
1186 * will not lower the minimum peer jitter, so we might
1189 if (max_selection_jitter < min_jitter) {
1190 VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
1191 max_selection_jitter, min_jitter, num_survivors);
1195 /* Delete survivor[max_idx] from the list
1196 * and go around again.
1198 VERB5 bb_error_msg("dropping survivor %d", max_idx);
1200 while (max_idx < num_survivors) {
1201 survivor[max_idx] = survivor[max_idx + 1];
1207 /* Combine the offsets of the clustering algorithm survivors
1208 * using a weighted average with weight determined by the root
1209 * distance. Compute the selection jitter as the weighted RMS
1210 * difference between the first survivor and the remaining
1211 * survivors. In some cases the inherent clock jitter can be
1212 * reduced by not using this algorithm, especially when frequent
1213 * clockhopping is involved. bbox: thus we don't do it.
1217 for (i = 0; i < num_survivors; i++) {
1219 x = root_distance(p);
1221 z += p->filter_offset / x;
1222 w += SQUARE(p->filter_offset - survivor[0].p->filter_offset) / x;
1224 //G.cluster_offset = z / y;
1225 //G.cluster_jitter = SQRT(w / y);
1228 /* Pick the best clock. If the old system peer is on the list
1229 * and at the same stratum as the first survivor on the list,
1230 * then don't do a clock hop. Otherwise, select the first
1231 * survivor on the list as the new system peer.
1234 if (G.last_update_peer
1235 && G.last_update_peer->lastpkt_stratum <= p->lastpkt_stratum
1237 /* Starting from 1 is ok here */
1238 for (i = 1; i < num_survivors; i++) {
1239 if (G.last_update_peer == survivor[i].p) {
1240 VERB4 bb_error_msg("keeping old synced peer");
1241 p = G.last_update_peer;
1246 G.last_update_peer = p;
1248 VERB3 bb_error_msg("selected peer %s filter_offset:%+f age:%f",
1251 G.cur_time - p->lastpkt_recv_time
1258 * Local clock discipline and its helpers
1261 set_new_values(int disc_state, double offset, double recv_time)
1263 /* Enter new state and set state variables. Note we use the time
1264 * of the last clock filter sample, which must be earlier than
1267 VERB3 bb_error_msg("disc_state=%d last update offset=%f recv_time=%f",
1268 disc_state, offset, recv_time);
1269 G.discipline_state = disc_state;
1270 G.last_update_offset = offset;
1271 G.last_update_recv_time = recv_time;
1273 /* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
1275 update_local_clock(peer_t *p)
1279 /* Note: can use G.cluster_offset instead: */
1280 double offset = p->filter_offset;
1281 double recv_time = p->lastpkt_recv_time;
1283 #if !USING_KERNEL_PLL_LOOP
1286 double since_last_update;
1287 double etemp, dtemp;
1289 abs_offset = fabs(offset);
1292 /* If needed, -S script can do it by looking at $offset
1293 * env var and killing parent */
1294 /* If the offset is too large, give up and go home */
1295 if (abs_offset > PANIC_THRESHOLD) {
1296 bb_error_msg_and_die("offset %f far too big, exiting", offset);
1300 /* If this is an old update, for instance as the result
1301 * of a system peer change, avoid it. We never use
1302 * an old sample or the same sample twice.
1304 if (recv_time <= G.last_update_recv_time) {
1305 VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it",
1306 G.last_update_recv_time, recv_time);
1307 return 0; /* "leave poll interval as is" */
1310 /* Clock state machine transition function. This is where the
1311 * action is and defines how the system reacts to large time
1312 * and frequency errors.
1314 since_last_update = recv_time - G.reftime;
1315 #if !USING_KERNEL_PLL_LOOP
1318 #if USING_INITIAL_FREQ_ESTIMATION
1319 if (G.discipline_state == STATE_FREQ) {
1320 /* Ignore updates until the stepout threshold */
1321 if (since_last_update < WATCH_THRESHOLD) {
1322 VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
1323 WATCH_THRESHOLD - since_last_update);
1324 return 0; /* "leave poll interval as is" */
1326 # if !USING_KERNEL_PLL_LOOP
1327 freq_drift = (offset - G.last_update_offset) / since_last_update;
1332 /* There are two main regimes: when the
1333 * offset exceeds the step threshold and when it does not.
1335 if (abs_offset > STEP_THRESHOLD) {
1336 switch (G.discipline_state) {
1338 /* The first outlyer: ignore it, switch to SPIK state */
1339 VERB3 bb_error_msg("offset:%+f - spike detected", offset);
1340 G.discipline_state = STATE_SPIK;
1341 return -1; /* "decrease poll interval" */
1344 /* Ignore succeeding outlyers until either an inlyer
1345 * is found or the stepout threshold is exceeded.
1347 if (since_last_update < WATCH_THRESHOLD) {
1348 VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains",
1349 WATCH_THRESHOLD - since_last_update);
1350 return -1; /* "decrease poll interval" */
1352 /* fall through: we need to step */
1355 /* Step the time and clamp down the poll interval.
1357 * In NSET state an initial frequency correction is
1358 * not available, usually because the frequency file has
1359 * not yet been written. Since the time is outside the
1360 * capture range, the clock is stepped. The frequency
1361 * will be set directly following the stepout interval.
1363 * In FSET state the initial frequency has been set
1364 * from the frequency file. Since the time is outside
1365 * the capture range, the clock is stepped immediately,
1366 * rather than after the stepout interval. Guys get
1367 * nervous if it takes 17 minutes to set the clock for
1370 * In SPIK state the stepout threshold has expired and
1371 * the phase is still above the step threshold. Note
1372 * that a single spike greater than the step threshold
1373 * is always suppressed, even at the longer poll
1376 VERB3 bb_error_msg("stepping time by %+f; poll_exp=MINPOLL", offset);
1378 if (option_mask32 & OPT_q) {
1379 /* We were only asked to set time once. Done. */
1383 G.polladj_count = 0;
1384 G.poll_exp = MINPOLL;
1385 G.stratum = MAXSTRAT;
1387 run_script("step", offset);
1389 #if USING_INITIAL_FREQ_ESTIMATION
1390 if (G.discipline_state == STATE_NSET) {
1391 set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
1392 return 1; /* "ok to increase poll interval" */
1395 abs_offset = offset = 0;
1396 set_new_values(STATE_SYNC, offset, recv_time);
1398 } else { /* abs_offset <= STEP_THRESHOLD */
1400 if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
1401 VERB3 bb_error_msg("small offset:%+f, disabling burst mode", offset);
1402 G.polladj_count = 0;
1403 G.poll_exp = MINPOLL;
1406 /* Compute the clock jitter as the RMS of exponentially
1407 * weighted offset differences. Used by the poll adjust code.
1409 etemp = SQUARE(G.discipline_jitter);
1410 dtemp = SQUARE(offset - G.last_update_offset);
1411 G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
1413 switch (G.discipline_state) {
1415 if (option_mask32 & OPT_q) {
1416 /* We were only asked to set time once.
1417 * The clock is precise enough, no need to step.
1421 #if USING_INITIAL_FREQ_ESTIMATION
1422 /* This is the first update received and the frequency
1423 * has not been initialized. The first thing to do
1424 * is directly measure the oscillator frequency.
1426 set_new_values(STATE_FREQ, offset, recv_time);
1428 set_new_values(STATE_SYNC, offset, recv_time);
1430 VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
1431 return 0; /* "leave poll interval as is" */
1433 #if 0 /* this is dead code for now */
1435 /* This is the first update and the frequency
1436 * has been initialized. Adjust the phase, but
1437 * don't adjust the frequency until the next update.
1439 set_new_values(STATE_SYNC, offset, recv_time);
1440 /* freq_drift remains 0 */
1444 #if USING_INITIAL_FREQ_ESTIMATION
1446 /* since_last_update >= WATCH_THRESHOLD, we waited enough.
1447 * Correct the phase and frequency and switch to SYNC state.
1448 * freq_drift was already estimated (see code above)
1450 set_new_values(STATE_SYNC, offset, recv_time);
1455 #if !USING_KERNEL_PLL_LOOP
1456 /* Compute freq_drift due to PLL and FLL contributions.
1458 * The FLL and PLL frequency gain constants
1459 * depend on the poll interval and Allan
1460 * intercept. The FLL is not used below one-half
1461 * the Allan intercept. Above that the loop gain
1462 * increases in steps to 1 / AVG.
1464 if ((1 << G.poll_exp) > ALLAN / 2) {
1465 etemp = FLL - G.poll_exp;
1468 freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp);
1470 /* For the PLL the integration interval
1471 * (numerator) is the minimum of the update
1472 * interval and poll interval. This allows
1473 * oversampling, but not undersampling.
1475 etemp = MIND(since_last_update, (1 << G.poll_exp));
1476 dtemp = (4 * PLL) << G.poll_exp;
1477 freq_drift += offset * etemp / SQUARE(dtemp);
1479 set_new_values(STATE_SYNC, offset, recv_time);
1482 if (G.stratum != p->lastpkt_stratum + 1) {
1483 G.stratum = p->lastpkt_stratum + 1;
1484 run_script("stratum", offset);
1488 if (G.discipline_jitter < G_precision_sec)
1489 G.discipline_jitter = G_precision_sec;
1490 G.offset_to_jitter_ratio = abs_offset / G.discipline_jitter;
1492 G.reftime = G.cur_time;
1493 G.ntp_status = p->lastpkt_status;
1494 G.refid = p->lastpkt_refid;
1495 G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
1496 dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(G.cluster_jitter));
1497 dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time) + abs_offset, MINDISP);
1498 G.rootdisp = p->lastpkt_rootdisp + dtemp;
1499 VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted);
1501 /* We are in STATE_SYNC now, but did not do adjtimex yet.
1502 * (Any other state does not reach this, they all return earlier)
1503 * By this time, freq_drift and offset are set
1504 * to values suitable for adjtimex.
1506 #if !USING_KERNEL_PLL_LOOP
1507 /* Calculate the new frequency drift and frequency stability (wander).
1508 * Compute the clock wander as the RMS of exponentially weighted
1509 * frequency differences. This is not used directly, but can,
1510 * along with the jitter, be a highly useful monitoring and
1513 dtemp = G.discipline_freq_drift + freq_drift;
1514 G.discipline_freq_drift = MAXD(MIND(MAXDRIFT, dtemp), -MAXDRIFT);
1515 etemp = SQUARE(G.discipline_wander);
1516 dtemp = SQUARE(dtemp);
1517 G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
1519 VERB3 bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
1520 G.discipline_freq_drift,
1521 (long)(G.discipline_freq_drift * 65536e6),
1523 G.discipline_wander);
1526 memset(&tmx, 0, sizeof(tmx));
1527 if (adjtimex(&tmx) < 0)
1528 bb_perror_msg_and_die("adjtimex");
1529 bb_error_msg("p adjtimex freq:%ld offset:%+ld status:0x%x tc:%ld",
1530 tmx.freq, tmx.offset, tmx.status, tmx.constant);
1533 memset(&tmx, 0, sizeof(tmx));
1535 //doesn't work, offset remains 0 (!) in kernel:
1536 //ntpd: set adjtimex freq:1786097 tmx.offset:77487
1537 //ntpd: prev adjtimex freq:1786097 tmx.offset:0
1538 //ntpd: cur adjtimex freq:1786097 tmx.offset:0
1539 tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET;
1540 /* 65536 is one ppm */
1541 tmx.freq = G.discipline_freq_drift * 65536e6;
1543 tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
1544 tmx.offset = (offset * 1000000); /* usec */
1545 tmx.status = STA_PLL;
1546 if (G.ntp_status & LI_PLUSSEC)
1547 tmx.status |= STA_INS;
1548 if (G.ntp_status & LI_MINUSSEC)
1549 tmx.status |= STA_DEL;
1551 tmx.constant = G.poll_exp - 4;
1553 * The below if statement should be unnecessary, but...
1554 * It looks like Linux kernel's PLL is far too gentle in changing
1555 * tmx.freq in response to clock offset. Offset keeps growing
1556 * and eventually we fall back to smaller poll intervals.
1557 * We can make correction more agressive (about x2) by supplying
1558 * PLL time constant which is one less than the real one.
1559 * To be on a safe side, let's do it only if offset is significantly
1560 * larger than jitter.
1562 if (tmx.constant > 0 && G.offset_to_jitter_ratio >= TIMECONST_HACK_GATE)
1565 //tmx.esterror = (uint32_t)(clock_jitter * 1e6);
1566 //tmx.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
1567 rc = adjtimex(&tmx);
1569 bb_perror_msg_and_die("adjtimex");
1570 /* NB: here kernel returns constant == G.poll_exp, not == G.poll_exp - 4.
1571 * Not sure why. Perhaps it is normal.
1573 VERB3 bb_error_msg("adjtimex:%d freq:%ld offset:%+ld status:0x%x",
1574 rc, tmx.freq, tmx.offset, tmx.status);
1575 G.kernel_freq_drift = tmx.freq / 65536;
1576 VERB2 bb_error_msg("update from:%s offset:%+f jitter:%f clock drift:%+.3fppm tc:%d",
1577 p->p_dotted, offset, G.discipline_jitter, (double)tmx.freq / 65536, (int)tmx.constant);
1579 return 1; /* "ok to increase poll interval" */
1584 * We've got a new reply packet from a peer, process it
1588 retry_interval(void)
1590 /* Local problem, want to retry soon */
1591 unsigned interval, r;
1592 interval = RETRY_INTERVAL;
1594 interval += r % (unsigned)(RETRY_INTERVAL / 4);
1595 VERB3 bb_error_msg("chose retry interval:%u", interval);
1599 poll_interval(int exponent)
1601 unsigned interval, r;
1602 exponent = G.poll_exp + exponent;
1605 interval = 1 << exponent;
1607 interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
1608 VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
1611 static NOINLINE void
1612 recv_and_process_peer_pkt(peer_t *p)
1617 double T1, T2, T3, T4;
1619 datapoint_t *datapoint;
1622 /* We can recvfrom here and check from.IP, but some multihomed
1623 * ntp servers reply from their *other IP*.
1624 * TODO: maybe we should check at least what we can: from.port == 123?
1626 size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
1628 bb_perror_msg("recv(%s) error", p->p_dotted);
1629 if (errno == EHOSTUNREACH || errno == EHOSTDOWN
1630 || errno == ENETUNREACH || errno == ENETDOWN
1631 || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
1634 //TODO: always do this?
1635 interval = retry_interval();
1636 goto set_next_and_ret;
1641 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1642 bb_error_msg("malformed packet received from %s", p->p_dotted);
1646 if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
1647 || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
1649 /* Somebody else's packet */
1653 /* We do not expect any more packets from this peer for now.
1654 * Closing the socket informs kernel about it.
1655 * We open a new socket when we send a new query.
1660 if ((msg.m_status & LI_ALARM) == LI_ALARM
1661 || msg.m_stratum == 0
1662 || msg.m_stratum > NTP_MAXSTRATUM
1664 // TODO: stratum 0 responses may have commands in 32-bit m_refid field:
1665 // "DENY", "RSTR" - peer does not like us at all
1666 // "RATE" - peer is overloaded, reduce polling freq
1667 interval = poll_interval(0);
1668 bb_error_msg("reply from %s: peer is unsynced, next query in %us", p->p_dotted, interval);
1669 goto set_next_and_ret;
1672 // /* Verify valid root distance */
1673 // if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
1674 // return; /* invalid header values */
1676 p->lastpkt_status = msg.m_status;
1677 p->lastpkt_stratum = msg.m_stratum;
1678 p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
1679 p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
1680 p->lastpkt_refid = msg.m_refid;
1683 * From RFC 2030 (with a correction to the delay math):
1685 * Timestamp Name ID When Generated
1686 * ------------------------------------------------------------
1687 * Originate Timestamp T1 time request sent by client
1688 * Receive Timestamp T2 time request received by server
1689 * Transmit Timestamp T3 time reply sent by server
1690 * Destination Timestamp T4 time reply received by client
1692 * The roundtrip delay and local clock offset are defined as
1694 * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
1697 T2 = lfp_to_d(msg.m_rectime);
1698 T3 = lfp_to_d(msg.m_xmttime);
1701 p->lastpkt_recv_time = T4;
1703 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
1704 p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
1705 datapoint = &p->filter_datapoint[p->datapoint_idx];
1706 datapoint->d_recv_time = T4;
1707 datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
1708 /* The delay calculation is a special case. In cases where the
1709 * server and client clocks are running at different rates and
1710 * with very fast networks, the delay can appear negative. In
1711 * order to avoid violating the Principle of Least Astonishment,
1712 * the delay is clamped not less than the system precision.
1714 p->lastpkt_delay = (T4 - T1) - (T3 - T2);
1715 if (p->lastpkt_delay < G_precision_sec)
1716 p->lastpkt_delay = G_precision_sec;
1717 datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
1718 if (!p->reachable_bits) {
1719 /* 1st datapoint ever - replicate offset in every element */
1721 for (i = 0; i < NUM_DATAPOINTS; i++) {
1722 p->filter_datapoint[i].d_offset = datapoint->d_offset;
1726 p->reachable_bits |= 1;
1727 if ((MAX_VERBOSE && G.verbose) || (option_mask32 & OPT_w)) {
1728 bb_error_msg("reply from %s: offset:%+f delay:%f status:0x%02x strat:%d refid:0x%08x rootdelay:%f reach:0x%02x",
1730 datapoint->d_offset,
1735 p->lastpkt_rootdelay,
1737 /* not shown: m_ppoll, m_precision_exp, m_rootdisp,
1738 * m_reftime, m_orgtime, m_rectime, m_xmttime
1743 /* Muck with statictics and update the clock */
1744 filter_datapoints(p);
1745 q = select_and_cluster();
1749 if (!(option_mask32 & OPT_w)) {
1750 rc = update_local_clock(q);
1751 /* If drift is dangerously large, immediately
1752 * drop poll interval one step down.
1754 if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) {
1755 VERB3 bb_error_msg("offset:%+f > POLLDOWN_OFFSET", q->filter_offset);
1760 /* else: no peer selected, rc = -1: we want to poll more often */
1763 /* Adjust the poll interval by comparing the current offset
1764 * with the clock jitter. If the offset is less than
1765 * the clock jitter times a constant, then the averaging interval
1766 * is increased, otherwise it is decreased. A bit of hysteresis
1767 * helps calm the dance. Works best using burst mode.
1769 if (rc > 0 && G.offset_to_jitter_ratio <= POLLADJ_GATE) {
1770 /* was += G.poll_exp but it is a bit
1771 * too optimistic for my taste at high poll_exp's */
1772 G.polladj_count += MINPOLL;
1773 if (G.polladj_count > POLLADJ_LIMIT) {
1774 G.polladj_count = 0;
1775 if (G.poll_exp < MAXPOLL) {
1777 VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
1778 G.discipline_jitter, G.poll_exp);
1781 VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count);
1784 G.polladj_count -= G.poll_exp * 2;
1785 if (G.polladj_count < -POLLADJ_LIMIT || G.poll_exp >= BIGPOLL) {
1787 G.polladj_count = 0;
1788 if (G.poll_exp > MINPOLL) {
1792 /* Correct p->next_action_time in each peer
1793 * which waits for sending, so that they send earlier.
1794 * Old pp->next_action_time are on the order
1795 * of t + (1 << old_poll_exp) + small_random,
1796 * we simply need to subtract ~half of that.
1798 for (item = G.ntp_peers; item != NULL; item = item->link) {
1799 peer_t *pp = (peer_t *) item->data;
1801 pp->next_action_time -= (1 << G.poll_exp);
1803 VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
1804 G.discipline_jitter, G.poll_exp);
1807 VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count);
1812 /* Decide when to send new query for this peer */
1813 interval = poll_interval(0);
1816 set_next(p, interval);
1819 #if ENABLE_FEATURE_NTPD_SERVER
1820 static NOINLINE void
1821 recv_and_process_client_pkt(void /*int fd*/)
1825 len_and_sockaddr *to;
1826 struct sockaddr *from;
1828 uint8_t query_status;
1829 l_fixedpt_t query_xmttime;
1831 to = get_sock_lsa(G_listen_fd);
1832 from = xzalloc(to->len);
1834 size = recv_from_to(G_listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
1835 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1838 if (errno == EAGAIN)
1840 bb_perror_msg_and_die("recv");
1842 addr = xmalloc_sockaddr2dotted_noport(from);
1843 bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
1848 query_status = msg.m_status;
1849 query_xmttime = msg.m_xmttime;
1851 /* Build a reply packet */
1852 memset(&msg, 0, sizeof(msg));
1853 msg.m_status = G.stratum < MAXSTRAT ? G.ntp_status : LI_ALARM;
1854 msg.m_status |= (query_status & VERSION_MASK);
1855 msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
1856 MODE_SERVER : MODE_SYM_PAS;
1857 msg.m_stratum = G.stratum;
1858 msg.m_ppoll = G.poll_exp;
1859 msg.m_precision_exp = G_precision_exp;
1860 /* this time was obtained between poll() and recv() */
1861 msg.m_rectime = d_to_lfp(G.cur_time);
1862 msg.m_xmttime = d_to_lfp(gettime1900d()); /* this instant */
1863 if (G.peer_cnt == 0) {
1864 /* we have no peers: "stratum 1 server" mode. reftime = our own time */
1865 G.reftime = G.cur_time;
1867 msg.m_reftime = d_to_lfp(G.reftime);
1868 msg.m_orgtime = query_xmttime;
1869 msg.m_rootdelay = d_to_sfp(G.rootdelay);
1870 //simple code does not do this, fix simple code!
1871 msg.m_rootdisp = d_to_sfp(G.rootdisp);
1872 //version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
1873 msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3;
1875 /* We reply from the local address packet was sent to,
1876 * this makes to/from look swapped here: */
1877 do_sendto(G_listen_fd,
1878 /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
1887 /* Upstream ntpd's options:
1889 * -4 Force DNS resolution of host names to the IPv4 namespace.
1890 * -6 Force DNS resolution of host names to the IPv6 namespace.
1891 * -a Require cryptographic authentication for broadcast client,
1892 * multicast client and symmetric passive associations.
1893 * This is the default.
1894 * -A Do not require cryptographic authentication for broadcast client,
1895 * multicast client and symmetric passive associations.
1896 * This is almost never a good idea.
1897 * -b Enable the client to synchronize to broadcast servers.
1899 * Specify the name and path of the configuration file,
1900 * default /etc/ntp.conf
1901 * -d Specify debugging mode. This option may occur more than once,
1902 * with each occurrence indicating greater detail of display.
1904 * Specify debugging level directly.
1906 * Specify the name and path of the frequency file.
1907 * This is the same operation as the "driftfile FILE"
1908 * configuration command.
1909 * -g Normally, ntpd exits with a message to the system log
1910 * if the offset exceeds the panic threshold, which is 1000 s
1911 * by default. This option allows the time to be set to any value
1912 * without restriction; however, this can happen only once.
1913 * If the threshold is exceeded after that, ntpd will exit
1914 * with a message to the system log. This option can be used
1915 * with the -q and -x options. See the tinker command for other options.
1917 * Chroot the server to the directory jaildir. This option also implies
1918 * that the server attempts to drop root privileges at startup
1919 * (otherwise, chroot gives very little additional security).
1920 * You may need to also specify a -u option.
1922 * Specify the name and path of the symmetric key file,
1923 * default /etc/ntp/keys. This is the same operation
1924 * as the "keys FILE" configuration command.
1926 * Specify the name and path of the log file. The default
1927 * is the system log file. This is the same operation as
1928 * the "logfile FILE" configuration command.
1929 * -L Do not listen to virtual IPs. The default is to listen.
1931 * -N To the extent permitted by the operating system,
1932 * run the ntpd at the highest priority.
1934 * Specify the name and path of the file used to record the ntpd
1935 * process ID. This is the same operation as the "pidfile FILE"
1936 * configuration command.
1938 * To the extent permitted by the operating system,
1939 * run the ntpd at the specified priority.
1940 * -q Exit the ntpd just after the first time the clock is set.
1941 * This behavior mimics that of the ntpdate program, which is
1942 * to be retired. The -g and -x options can be used with this option.
1943 * Note: The kernel time discipline is disabled with this option.
1945 * Specify the default propagation delay from the broadcast/multicast
1946 * server to this client. This is necessary only if the delay
1947 * cannot be computed automatically by the protocol.
1949 * Specify the directory path for files created by the statistics
1950 * facility. This is the same operation as the "statsdir DIR"
1951 * configuration command.
1953 * Add a key number to the trusted key list. This option can occur
1956 * Specify a user, and optionally a group, to switch to.
1959 * Add a system variable listed by default.
1960 * -x Normally, the time is slewed if the offset is less than the step
1961 * threshold, which is 128 ms by default, and stepped if above
1962 * the threshold. This option sets the threshold to 600 s, which is
1963 * well within the accuracy window to set the clock manually.
1964 * Note: since the slew rate of typical Unix kernels is limited
1965 * to 0.5 ms/s, each second of adjustment requires an amortization
1966 * interval of 2000 s. Thus, an adjustment as much as 600 s
1967 * will take almost 14 days to complete. This option can be used
1968 * with the -g and -q options. See the tinker command for other options.
1969 * Note: The kernel time discipline is disabled with this option.
1972 /* By doing init in a separate function we decrease stack usage
1975 static NOINLINE void ntp_init(char **argv)
1983 bb_error_msg_and_die(bb_msg_you_must_be_root);
1985 /* Set some globals */
1986 G.stratum = MAXSTRAT;
1988 G.poll_exp = BURSTPOLL; /* speeds up initial sync */
1989 G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
1993 opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
1994 opts = getopt32(argv,
1996 "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
1998 "46aAbgL", /* compat, ignored */
1999 &peers, &G.script_name, &G.verbose);
2000 if (!(opts & (OPT_p|OPT_l)))
2002 // if (opts & OPT_x) /* disable stepping, only slew is allowed */
2003 // G.time_was_stepped = 1;
2006 add_peers(llist_pop(&peers));
2008 /* -l but no peers: "stratum 1 server" mode */
2011 if (!(opts & OPT_n)) {
2012 bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
2013 logmode = LOGMODE_NONE;
2015 #if ENABLE_FEATURE_NTPD_SERVER
2018 G_listen_fd = create_and_bind_dgram_or_die(NULL, 123);
2019 socket_want_pktinfo(G_listen_fd);
2020 setsockopt(G_listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
2023 /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
2025 setpriority(PRIO_PROCESS, 0, -15);
2027 /* If network is up, syncronization occurs in ~10 seconds.
2028 * We give "ntpd -q" 10 seconds to get first reply,
2029 * then another 50 seconds to finish syncing.
2031 * I tested ntpd 4.2.6p1 and apparently it never exits
2032 * (will try forever), but it does not feel right.
2033 * The goal of -q is to act like ntpdate: set time
2034 * after a reasonably small period of polling, or fail.
2037 option_mask32 |= OPT_qq;
2054 int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
2055 int ntpd_main(int argc UNUSED_PARAM, char **argv)
2063 memset(&G, 0, sizeof(G));
2064 SET_PTR_TO_GLOBALS(&G);
2068 /* If ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
2069 cnt = G.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
2070 idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
2071 pfd = xzalloc(sizeof(pfd[0]) * cnt);
2073 /* Countdown: we never sync before we sent INITIAL_SAMPLES+1
2074 * packets to each peer.
2075 * NB: if some peer is not responding, we may end up sending
2076 * fewer packets to it and more to other peers.
2077 * NB2: sync usually happens using INITIAL_SAMPLES packets,
2078 * since last reply does not come back instantaneously.
2080 cnt = G.peer_cnt * (INITIAL_SAMPLES + 1);
2082 while (!bb_got_signal) {
2088 /* Nothing between here and poll() blocks for any significant time */
2090 nextaction = G.cur_time + 3600;
2093 #if ENABLE_FEATURE_NTPD_SERVER
2094 if (G_listen_fd != -1) {
2095 pfd[0].fd = G_listen_fd;
2096 pfd[0].events = POLLIN;
2100 /* Pass over peer list, send requests, time out on receives */
2101 for (item = G.ntp_peers; item != NULL; item = item->link) {
2102 peer_t *p = (peer_t *) item->data;
2104 if (p->next_action_time <= G.cur_time) {
2105 if (p->p_fd == -1) {
2106 /* Time to send new req */
2108 G.initial_poll_complete = 1;
2110 send_query_to_peer(p);
2112 /* Timed out waiting for reply */
2115 timeout = poll_interval(-2); /* -2: try a bit sooner */
2116 bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
2117 p->p_dotted, p->reachable_bits, timeout);
2118 set_next(p, timeout);
2122 if (p->next_action_time < nextaction)
2123 nextaction = p->next_action_time;
2126 /* Wait for reply from this peer */
2127 pfd[i].fd = p->p_fd;
2128 pfd[i].events = POLLIN;
2134 timeout = nextaction - G.cur_time;
2137 timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
2139 /* Here we may block */
2141 if (i > (ENABLE_FEATURE_NTPD_SERVER && G_listen_fd != -1)) {
2142 /* We wait for at least one reply.
2143 * Poll for it, without wasting time for message.
2144 * Since replies often come under 1 second, this also
2145 * reduces clutter in logs.
2147 nfds = poll(pfd, i, 1000);
2153 bb_error_msg("poll:%us sockets:%u interval:%us", timeout, i, 1 << G.poll_exp);
2155 nfds = poll(pfd, i, timeout * 1000);
2157 gettime1900d(); /* sets G.cur_time */
2159 if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
2160 /* Useful for updating battery-backed RTC and such */
2161 run_script("periodic", G.last_update_offset);
2162 gettime1900d(); /* sets G.cur_time */
2167 /* Process any received packets */
2169 #if ENABLE_FEATURE_NTPD_SERVER
2170 if (G.listen_fd != -1) {
2171 if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
2173 recv_and_process_client_pkt(/*G.listen_fd*/);
2174 gettime1900d(); /* sets G.cur_time */
2179 for (; nfds != 0 && j < i; j++) {
2180 if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
2182 * At init, alarm was set to 10 sec.
2183 * Now we did get a reply.
2184 * Increase timeout to 50 seconds to finish syncing.
2186 if (option_mask32 & OPT_qq) {
2187 option_mask32 &= ~OPT_qq;
2191 recv_and_process_peer_pkt(idx2peer[j]);
2192 gettime1900d(); /* sets G.cur_time */
2195 } /* while (!bb_got_signal) */
2197 kill_myself_with_sig(bb_got_signal);
2205 /*** openntpd-4.6 uses only adjtime, not adjtimex ***/
2207 /*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/
2211 direct_freq(double fp_offset)
2215 * If the kernel is enabled, we need the residual offset to
2216 * calculate the frequency correction.
2218 if (pll_control && kern_enable) {
2219 memset(&ntv, 0, sizeof(ntv));
2222 clock_offset = ntv.offset / 1e9;
2223 #else /* STA_NANO */
2224 clock_offset = ntv.offset / 1e6;
2225 #endif /* STA_NANO */
2226 drift_comp = FREQTOD(ntv.freq);
2228 #endif /* KERNEL_PLL */
2229 set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp);
2235 set_freq(double freq) /* frequency update */
2243 * If the kernel is enabled, update the kernel frequency.
2245 if (pll_control && kern_enable) {
2246 memset(&ntv, 0, sizeof(ntv));
2247 ntv.modes = MOD_FREQUENCY;
2248 ntv.freq = DTOFREQ(drift_comp);
2250 snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6);
2251 report_event(EVNT_FSET, NULL, tbuf);
2253 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2254 report_event(EVNT_FSET, NULL, tbuf);
2256 #else /* KERNEL_PLL */
2257 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2258 report_event(EVNT_FSET, NULL, tbuf);
2259 #endif /* KERNEL_PLL */
2268 * This code segment works when clock adjustments are made using
2269 * precision time kernel support and the ntp_adjtime() system
2270 * call. This support is available in Solaris 2.6 and later,
2271 * Digital Unix 4.0 and later, FreeBSD, Linux and specially
2272 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
2273 * DECstation 5000/240 and Alpha AXP, additional kernel
2274 * modifications provide a true microsecond clock and nanosecond
2275 * clock, respectively.
2277 * Important note: The kernel discipline is used only if the
2278 * step threshold is less than 0.5 s, as anything higher can
2279 * lead to overflow problems. This might occur if some misguided
2280 * lad set the step threshold to something ridiculous.
2282 if (pll_control && kern_enable) {
2284 #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST)
2287 * We initialize the structure for the ntp_adjtime()
2288 * system call. We have to convert everything to
2289 * microseconds or nanoseconds first. Do not update the
2290 * system variables if the ext_enable flag is set. In
2291 * this case, the external clock driver will update the
2292 * variables, which will be read later by the local
2293 * clock driver. Afterwards, remember the time and
2294 * frequency offsets for jitter and stability values and
2295 * to update the frequency file.
2297 memset(&ntv, 0, sizeof(ntv));
2299 ntv.modes = MOD_STATUS;
2302 ntv.modes = MOD_BITS | MOD_NANO;
2303 #else /* STA_NANO */
2304 ntv.modes = MOD_BITS;
2305 #endif /* STA_NANO */
2306 if (clock_offset < 0)
2311 ntv.offset = (int32)(clock_offset * 1e9 + dtemp);
2312 ntv.constant = sys_poll;
2313 #else /* STA_NANO */
2314 ntv.offset = (int32)(clock_offset * 1e6 + dtemp);
2315 ntv.constant = sys_poll - 4;
2316 #endif /* STA_NANO */
2317 ntv.esterror = (u_int32)(clock_jitter * 1e6);
2318 ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
2319 ntv.status = STA_PLL;
2322 * Enable/disable the PPS if requested.
2325 if (!(pll_status & STA_PPSTIME))
2326 report_event(EVNT_KERN,
2327 NULL, "PPS enabled");
2328 ntv.status |= STA_PPSTIME | STA_PPSFREQ;
2330 if (pll_status & STA_PPSTIME)
2331 report_event(EVNT_KERN,
2332 NULL, "PPS disabled");
2333 ntv.status &= ~(STA_PPSTIME |
2336 if (sys_leap == LEAP_ADDSECOND)
2337 ntv.status |= STA_INS;
2338 else if (sys_leap == LEAP_DELSECOND)
2339 ntv.status |= STA_DEL;
2343 * Pass the stuff to the kernel. If it squeals, turn off
2344 * the pps. In any case, fetch the kernel offset,
2345 * frequency and jitter.
2347 if (ntp_adjtime(&ntv) == TIME_ERROR) {
2348 if (!(ntv.status & STA_PPSSIGNAL))
2349 report_event(EVNT_KERN, NULL,
2352 pll_status = ntv.status;
2354 clock_offset = ntv.offset / 1e9;
2355 #else /* STA_NANO */
2356 clock_offset = ntv.offset / 1e6;
2357 #endif /* STA_NANO */
2358 clock_frequency = FREQTOD(ntv.freq);
2361 * If the kernel PPS is lit, monitor its performance.
2363 if (ntv.status & STA_PPSTIME) {
2365 clock_jitter = ntv.jitter / 1e9;
2366 #else /* STA_NANO */
2367 clock_jitter = ntv.jitter / 1e6;
2368 #endif /* STA_NANO */
2371 #if defined(STA_NANO) && NTP_API == 4
2373 * If the TAI changes, update the kernel TAI.
2375 if (loop_tai != sys_tai) {
2377 ntv.modes = MOD_TAI;
2378 ntv.constant = sys_tai;
2381 #endif /* STA_NANO */
2383 #endif /* KERNEL_PLL */