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;
223 /* when to send new query (if p_fd == -1)
224 * or when receive times out (if p_fd >= 0): */
227 uint32_t lastpkt_refid;
228 uint8_t lastpkt_status;
229 uint8_t lastpkt_stratum;
230 uint8_t reachable_bits;
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
282 /* refid: 32-bit code identifying the particular server or reference clock
283 * in stratum 0 packets this is a four-character ASCII string,
284 * called the kiss code, used for debugging and monitoring
285 * in stratum 1 packets this is a four-character ASCII string
286 * assigned to the reference clock by IANA. Example: "GPS "
287 * in stratum 2+ packets, it's IPv4 address or 4 first bytes
288 * of MD5 hash of IPv6
292 /* precision is defined as the larger of the resolution and time to
293 * read the clock, in log2 units. For instance, the precision of a
294 * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
295 * system clock hardware representation is to the nanosecond.
297 * Delays, jitters of various kinds are clamped down to precision.
299 * If precision_sec is too large, discipline_jitter gets clamped to it
300 * and if offset is smaller than discipline_jitter * POLLADJ_GATE, poll
301 * interval grows even though we really can benefit from staying at
302 * smaller one, collecting non-lagged datapoits and correcting offset.
303 * (Lagged datapoits exist when poll_exp is large but we still have
304 * systematic offset error - the time distance between datapoints
305 * is significant and older datapoints have smaller offsets.
306 * This makes our offset estimation a bit smaller than reality)
307 * Due to this effect, setting G_precision_sec close to
308 * STEP_THRESHOLD isn't such a good idea - offsets may grow
309 * too big and we will step. I observed it with -6.
311 * OTOH, setting precision_sec far too small would result in futile
312 * attempts to syncronize to an unachievable precision.
314 * -6 is 1/64 sec, -7 is 1/128 sec and so on.
315 * -8 is 1/256 ~= 0.003906 (worked well for me --vda)
316 * -9 is 1/512 ~= 0.001953 (let's try this for some time)
318 #define G_precision_exp -9
320 * G_precision_exp is used only for construction outgoing packets.
321 * It's ok to set G_precision_sec to a slightly different value
322 * (One which is "nicer looking" in logs).
323 * Exact value would be (1.0 / (1 << (- G_precision_exp))):
325 #define G_precision_sec 0.002
327 /* Bool. After set to 1, never goes back to 0: */
328 smallint initial_poll_complete;
330 #define STATE_NSET 0 /* initial state, "nothing is set" */
331 //#define STATE_FSET 1 /* frequency set from file */
332 #define STATE_SPIK 2 /* spike detected */
333 //#define STATE_FREQ 3 /* initial frequency */
334 #define STATE_SYNC 4 /* clock synchronized (normal operation) */
335 uint8_t discipline_state; // doc calls it c.state
336 uint8_t poll_exp; // s.poll
337 int polladj_count; // c.count
338 long kernel_freq_drift;
339 peer_t *last_update_peer;
340 double last_update_offset; // c.last
341 double last_update_recv_time; // s.t
342 double discipline_jitter; // c.jitter
343 /* Since we only compare it with ints, can simplify code
344 * by not making this variable floating point:
346 unsigned offset_to_jitter_ratio;
347 //double cluster_offset; // s.offset
348 //double cluster_jitter; // s.jitter
349 #if !USING_KERNEL_PLL_LOOP
350 double discipline_freq_drift; // c.freq
351 /* Maybe conditionally calculate wander? it's used only for logging */
352 double discipline_wander; // c.wander
355 #define G (*ptr_to_globals)
357 static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
360 #define VERB1 if (MAX_VERBOSE && G.verbose)
361 #define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
362 #define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
363 #define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
364 #define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
367 static double LOG2D(int a)
370 return 1.0 / (1UL << -a);
373 static ALWAYS_INLINE double SQUARE(double x)
377 static ALWAYS_INLINE double MAXD(double a, double b)
383 static ALWAYS_INLINE double MIND(double a, double b)
389 static NOINLINE double my_SQRT(double X)
396 double Xhalf = X * 0.5;
398 /* Fast and good approximation to 1/sqrt(X), black magic */
400 /*v.i = 0x5f3759df - (v.i >> 1);*/
401 v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
402 invsqrt = v.f; /* better than 0.2% accuracy */
404 /* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
405 * f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
407 * f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
408 * x1 = x0 - (X*x0*x0*x0/2 - x0/2) = 1.5*x0 - X*x0*x0*x0/2 = x0*(1.5 - (X/2)*x0*x0)
410 invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
411 /* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
412 /* With 4 iterations, more than half results will be exact,
413 * at 6th iterations result stabilizes with about 72% results exact.
414 * We are well satisfied with 0.05% accuracy.
417 return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
419 static ALWAYS_INLINE double SQRT(double X)
421 /* If this arch doesn't use IEEE 754 floats, fall back to using libm */
422 if (sizeof(float) != 4)
425 /* This avoids needing libm, saves about 0.5k on x86-32 */
433 gettimeofday(&tv, NULL); /* never fails */
434 G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
439 d_to_tv(double d, struct timeval *tv)
441 tv->tv_sec = (long)d;
442 tv->tv_usec = (d - tv->tv_sec) * 1000000;
446 lfp_to_d(l_fixedpt_t lfp)
449 lfp.int_partl = ntohl(lfp.int_partl);
450 lfp.fractionl = ntohl(lfp.fractionl);
451 ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
455 sfp_to_d(s_fixedpt_t sfp)
458 sfp.int_parts = ntohs(sfp.int_parts);
459 sfp.fractions = ntohs(sfp.fractions);
460 ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
463 #if ENABLE_FEATURE_NTPD_SERVER
468 lfp.int_partl = (uint32_t)d;
469 lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
470 lfp.int_partl = htonl(lfp.int_partl);
471 lfp.fractionl = htonl(lfp.fractionl);
478 sfp.int_parts = (uint16_t)d;
479 sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
480 sfp.int_parts = htons(sfp.int_parts);
481 sfp.fractions = htons(sfp.fractions);
487 dispersion(const datapoint_t *dp)
489 return dp->d_dispersion + FREQ_TOLERANCE * (G.cur_time - dp->d_recv_time);
493 root_distance(peer_t *p)
495 /* The root synchronization distance is the maximum error due to
496 * all causes of the local clock relative to the primary server.
497 * It is defined as half the total delay plus total dispersion
500 return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2
501 + p->lastpkt_rootdisp
502 + p->filter_dispersion
503 + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time)
508 set_next(peer_t *p, unsigned t)
510 p->next_action_time = G.cur_time + t;
514 * Peer clock filter and its helpers
517 filter_datapoints(peer_t *p)
524 /* Simulations have shown that use of *averaged* offset for p->filter_offset
525 * is in fact worse than simply using last received one: with large poll intervals
526 * (>= 2048) averaging code uses offset values which are outdated by hours,
527 * and time/frequency correction goes totally wrong when fed essentially bogus offsets.
530 double minoff, maxoff, w;
531 double x = x; /* for compiler */
532 double oldest_off = oldest_off;
533 double oldest_age = oldest_age;
534 double newest_off = newest_off;
535 double newest_age = newest_age;
537 fdp = p->filter_datapoint;
539 minoff = maxoff = fdp[0].d_offset;
540 for (i = 1; i < NUM_DATAPOINTS; i++) {
541 if (minoff > fdp[i].d_offset)
542 minoff = fdp[i].d_offset;
543 if (maxoff < fdp[i].d_offset)
544 maxoff = fdp[i].d_offset;
547 idx = p->datapoint_idx; /* most recent datapoint's index */
549 * Drop two outliers and take weighted average of the rest:
550 * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
551 * we use older6/32, not older6/64 since sum of weights should be 1:
552 * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
558 * filter_dispersion = \ -------------
565 for (i = 0; i < NUM_DATAPOINTS; i++) {
567 bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
570 fdp[idx].d_dispersion, dispersion(&fdp[idx]),
571 G.cur_time - fdp[idx].d_recv_time,
572 (minoff == fdp[idx].d_offset || maxoff == fdp[idx].d_offset)
573 ? " (outlier by offset)" : ""
577 sum += dispersion(&fdp[idx]) / (2 << i);
579 if (minoff == fdp[idx].d_offset) {
580 minoff -= 1; /* so that we don't match it ever again */
582 if (maxoff == fdp[idx].d_offset) {
585 oldest_off = fdp[idx].d_offset;
586 oldest_age = G.cur_time - fdp[idx].d_recv_time;
589 newest_off = oldest_off;
590 newest_age = oldest_age;
597 idx = (idx - 1) & (NUM_DATAPOINTS - 1);
599 p->filter_dispersion = sum;
600 wavg += x; /* add another older6/64 to form older6/32 */
601 /* Fix systematic underestimation with large poll intervals.
602 * Imagine that we still have a bit of uncorrected drift,
603 * and poll interval is big (say, 100 sec). Offsets form a progression:
604 * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
605 * The algorithm above drops 0.0 and 0.7 as outliers,
606 * and then we have this estimation, ~25% off from 0.7:
607 * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
609 x = oldest_age - newest_age;
611 x = newest_age / x; /* in above example, 100 / (600 - 100) */
612 if (x < 1) { /* paranoia check */
613 x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
617 p->filter_offset = wavg;
621 fdp = p->filter_datapoint;
622 idx = p->datapoint_idx; /* most recent datapoint's index */
624 /* filter_offset: simply use the most recent value */
625 p->filter_offset = fdp[idx].d_offset;
629 * filter_dispersion = \ -------------
636 for (i = 0; i < NUM_DATAPOINTS; i++) {
637 sum += dispersion(&fdp[idx]) / (2 << i);
638 wavg += fdp[idx].d_offset;
639 idx = (idx - 1) & (NUM_DATAPOINTS - 1);
641 wavg /= NUM_DATAPOINTS;
642 p->filter_dispersion = sum;
645 /* +----- -----+ ^ 1/2
649 * filter_jitter = | --- * / (avg-offset_j) |
653 * where n is the number of valid datapoints in the filter (n > 1);
654 * if filter_jitter < precision then filter_jitter = precision
657 for (i = 0; i < NUM_DATAPOINTS; i++) {
658 sum += SQUARE(wavg - fdp[i].d_offset);
660 sum = SQRT(sum / NUM_DATAPOINTS);
661 p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
663 VERB3 bb_error_msg("filter offset:%+f disp:%f jitter:%f",
665 p->filter_dispersion,
670 reset_peer_stats(peer_t *p, double offset)
673 bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
675 for (i = 0; i < NUM_DATAPOINTS; i++) {
677 p->filter_datapoint[i].d_recv_time += offset;
678 if (p->filter_datapoint[i].d_offset != 0) {
679 p->filter_datapoint[i].d_offset -= offset;
680 //bb_error_msg("p->filter_datapoint[%d].d_offset %f -> %f",
682 // p->filter_datapoint[i].d_offset + offset,
683 // p->filter_datapoint[i].d_offset);
686 p->filter_datapoint[i].d_recv_time = G.cur_time;
687 p->filter_datapoint[i].d_offset = 0;
688 p->filter_datapoint[i].d_dispersion = MAXDISP;
692 p->lastpkt_recv_time += offset;
694 p->reachable_bits = 0;
695 p->lastpkt_recv_time = G.cur_time;
697 filter_datapoints(p); /* recalc p->filter_xxx */
698 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
706 p = xzalloc(sizeof(*p));
707 p->p_lsa = xhost2sockaddr(s, 123);
708 p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
710 p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
711 p->next_action_time = G.cur_time; /* = set_next(p, 0); */
712 reset_peer_stats(p, 16 * STEP_THRESHOLD);
714 llist_add_to(&G.ntp_peers, p);
720 const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
721 msg_t *msg, ssize_t len)
727 ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
729 ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
732 bb_perror_msg("send failed");
739 send_query_to_peer(peer_t *p)
741 /* Why do we need to bind()?
742 * See what happens when we don't bind:
744 * socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
745 * setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
746 * gettimeofday({1259071266, 327885}, NULL) = 0
747 * sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
748 * ^^^ we sent it from some source port picked by kernel.
749 * time(NULL) = 1259071266
750 * write(2, "ntpd: entering poll 15 secs\n", 28) = 28
751 * poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
752 * recv(3, "yyy", 68, MSG_DONTWAIT) = 48
753 * ^^^ this recv will receive packets to any local port!
755 * Uncomment this and use strace to see it in action:
757 #define PROBE_LOCAL_ADDR /* { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } */
761 len_and_sockaddr *local_lsa;
763 family = p->p_lsa->u.sa.sa_family;
764 p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
765 /* local_lsa has "null" address and port 0 now.
766 * bind() ensures we have a *particular port* selected by kernel
767 * and remembered in p->p_fd, thus later recv(p->p_fd)
768 * receives only packets sent to this port.
771 xbind(fd, &local_lsa->u.sa, local_lsa->len);
773 #if ENABLE_FEATURE_IPV6
774 if (family == AF_INET)
776 setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
780 /* Emit message _before_ attempted send. Think of a very short
781 * roundtrip networks: we need to go back to recv loop ASAP,
782 * to reduce delay. Printing messages after send works against that.
784 VERB1 bb_error_msg("sending query to %s", p->p_dotted);
787 * Send out a random 64-bit number as our transmit time. The NTP
788 * server will copy said number into the originate field on the
789 * response that it sends us. This is totally legal per the SNTP spec.
791 * The impact of this is two fold: we no longer send out the current
792 * system time for the world to see (which may aid an attacker), and
793 * it gives us a (not very secure) way of knowing that we're not
794 * getting spoofed by an attacker that can't capture our traffic
795 * but can spoof packets from the NTP server we're communicating with.
797 * Save the real transmit timestamp locally.
799 p->p_xmt_msg.m_xmttime.int_partl = random();
800 p->p_xmt_msg.m_xmttime.fractionl = random();
801 p->p_xmttime = gettime1900d();
803 if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
804 &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
808 set_next(p, RETRY_INTERVAL);
812 p->reachable_bits <<= 1;
813 set_next(p, RESPONSE_INTERVAL);
817 /* Note that there is no provision to prevent several run_scripts
818 * to be done in quick succession. In fact, it happens rather often
819 * if initial syncronization results in a step.
820 * You will see "step" and then "stratum" script runs, sometimes
821 * as close as only 0.002 seconds apart.
822 * Script should be ready to deal with this.
824 static void run_script(const char *action, double offset)
827 char *env1, *env2, *env3, *env4;
832 argv[0] = (char*) G.script_name;
833 argv[1] = (char*) action;
836 VERB1 bb_error_msg("executing '%s %s'", G.script_name, action);
838 env1 = xasprintf("%s=%u", "stratum", G.stratum);
840 env2 = xasprintf("%s=%ld", "freq_drift_ppm", G.kernel_freq_drift);
842 env3 = xasprintf("%s=%u", "poll_interval", 1 << G.poll_exp);
844 env4 = xasprintf("%s=%f", "offset", offset);
846 /* Other items of potential interest: selected peer,
847 * rootdelay, reftime, rootdisp, refid, ntp_status,
848 * last_update_offset, last_update_recv_time, discipline_jitter,
849 * how many peers have reachable_bits = 0?
852 /* Don't want to wait: it may run hwclock --systohc, and that
853 * may take some time (seconds): */
854 /*spawn_and_wait(argv);*/
858 unsetenv("freq_drift_ppm");
859 unsetenv("poll_interval");
866 G.last_script_run = G.cur_time;
870 step_time(double offset)
874 struct timeval tvc, tvn;
875 char buf[sizeof("yyyy-mm-dd hh:mm:ss") + /*paranoia:*/ 4];
878 gettimeofday(&tvc, NULL); /* never fails */
879 dtime = tvc.tv_sec + (1.0e-6 * tvc.tv_usec) + offset;
880 d_to_tv(dtime, &tvn);
881 if (settimeofday(&tvn, NULL) == -1)
882 bb_perror_msg_and_die("settimeofday");
886 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
887 bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
890 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
891 bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
893 /* Correct various fields which contain time-relative values: */
895 /* p->lastpkt_recv_time, p->next_action_time and such: */
896 for (item = G.ntp_peers; item != NULL; item = item->link) {
897 peer_t *pp = (peer_t *) item->data;
898 reset_peer_stats(pp, offset);
899 //bb_error_msg("offset:%+f pp->next_action_time:%f -> %f",
900 // offset, pp->next_action_time, pp->next_action_time + offset);
901 pp->next_action_time += offset;
904 G.cur_time += offset;
905 G.last_update_recv_time += offset;
906 G.last_script_run += offset;
911 * Selection and clustering, and their helpers
917 double opt_rd; /* optimization */
920 compare_point_edge(const void *aa, const void *bb)
922 const point_t *a = aa;
923 const point_t *b = bb;
924 if (a->edge < b->edge) {
927 return (a->edge > b->edge);
934 compare_survivor_metric(const void *aa, const void *bb)
936 const survivor_t *a = aa;
937 const survivor_t *b = bb;
938 if (a->metric < b->metric) {
941 return (a->metric > b->metric);
944 fit(peer_t *p, double rd)
946 if ((p->reachable_bits & (p->reachable_bits-1)) == 0) {
947 /* One or zero bits in reachable_bits */
948 VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
951 #if 0 /* we filter out such packets earlier */
952 if ((p->lastpkt_status & LI_ALARM) == LI_ALARM
953 || p->lastpkt_stratum >= MAXSTRAT
955 VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
959 /* rd is root_distance(p) */
960 if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
961 VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
965 // /* Do we have a loop? */
966 // if (p->refid == p->dstaddr || p->refid == s.refid)
971 select_and_cluster(void)
976 int size = 3 * G.peer_cnt;
977 /* for selection algorithm */
979 unsigned num_points, num_candidates;
981 unsigned num_falsetickers;
982 /* for cluster algorithm */
983 survivor_t survivor[size];
984 unsigned num_survivors;
990 if (G.initial_poll_complete) while (item != NULL) {
993 p = (peer_t *) item->data;
994 rd = root_distance(p);
995 offset = p->filter_offset;
1001 VERB4 bb_error_msg("interval: [%f %f %f] %s",
1007 point[num_points].p = p;
1008 point[num_points].type = -1;
1009 point[num_points].edge = offset - rd;
1010 point[num_points].opt_rd = rd;
1012 point[num_points].p = p;
1013 point[num_points].type = 0;
1014 point[num_points].edge = offset;
1015 point[num_points].opt_rd = rd;
1017 point[num_points].p = p;
1018 point[num_points].type = 1;
1019 point[num_points].edge = offset + rd;
1020 point[num_points].opt_rd = rd;
1024 num_candidates = num_points / 3;
1025 if (num_candidates == 0) {
1026 VERB3 bb_error_msg("no valid datapoints, no peer selected");
1029 //TODO: sorting does not seem to be done in reference code
1030 qsort(point, num_points, sizeof(point[0]), compare_point_edge);
1032 /* Start with the assumption that there are no falsetickers.
1033 * Attempt to find a nonempty intersection interval containing
1034 * the midpoints of all truechimers.
1035 * If a nonempty interval cannot be found, increase the number
1036 * of assumed falsetickers by one and try again.
1037 * If a nonempty interval is found and the number of falsetickers
1038 * is less than the number of truechimers, a majority has been found
1039 * and the midpoint of each truechimer represents
1040 * the candidates available to the cluster algorithm.
1042 num_falsetickers = 0;
1045 unsigned num_midpoints = 0;
1050 for (i = 0; i < num_points; i++) {
1052 * if (point[i].type == -1) c++;
1053 * if (point[i].type == 1) c--;
1054 * and it's simpler to do it this way:
1057 if (c >= num_candidates - num_falsetickers) {
1058 /* If it was c++ and it got big enough... */
1059 low = point[i].edge;
1062 if (point[i].type == 0)
1066 for (i = num_points-1; i >= 0; i--) {
1068 if (c >= num_candidates - num_falsetickers) {
1069 high = point[i].edge;
1072 if (point[i].type == 0)
1075 /* If the number of midpoints is greater than the number
1076 * of allowed falsetickers, the intersection contains at
1077 * least one truechimer with no midpoint - bad.
1078 * Also, interval should be nonempty.
1080 if (num_midpoints <= num_falsetickers && low < high)
1083 if (num_falsetickers * 2 >= num_candidates) {
1084 VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected",
1085 num_falsetickers, num_candidates);
1089 VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
1090 low, high, num_candidates, num_falsetickers);
1094 /* Construct a list of survivors (p, metric)
1095 * from the chime list, where metric is dominated
1096 * first by stratum and then by root distance.
1097 * All other things being equal, this is the order of preference.
1100 for (i = 0; i < num_points; i++) {
1101 if (point[i].edge < low || point[i].edge > high)
1104 survivor[num_survivors].p = p;
1105 /* x.opt_rd == root_distance(p); */
1106 survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + point[i].opt_rd;
1107 VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s",
1108 num_survivors, survivor[num_survivors].metric, p->p_dotted);
1111 /* There must be at least MIN_SELECTED survivors to satisfy the
1112 * correctness assertions. Ordinarily, the Byzantine criteria
1113 * require four survivors, but for the demonstration here, one
1116 if (num_survivors < MIN_SELECTED) {
1117 VERB3 bb_error_msg("num_survivors %d < %d, no peer selected",
1118 num_survivors, MIN_SELECTED);
1122 //looks like this is ONLY used by the fact that later we pick survivor[0].
1123 //we can avoid sorting then, just find the minimum once!
1124 qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric);
1126 /* For each association p in turn, calculate the selection
1127 * jitter p->sjitter as the square root of the sum of squares
1128 * (p->offset - q->offset) over all q associations. The idea is
1129 * to repeatedly discard the survivor with maximum selection
1130 * jitter until a termination condition is met.
1133 unsigned max_idx = max_idx;
1134 double max_selection_jitter = max_selection_jitter;
1135 double min_jitter = min_jitter;
1137 if (num_survivors <= MIN_CLUSTERED) {
1138 VERB3 bb_error_msg("num_survivors %d <= %d, not discarding more",
1139 num_survivors, MIN_CLUSTERED);
1143 /* To make sure a few survivors are left
1144 * for the clustering algorithm to chew on,
1145 * we stop if the number of survivors
1146 * is less than or equal to MIN_CLUSTERED (3).
1148 for (i = 0; i < num_survivors; i++) {
1149 double selection_jitter_sq;
1152 if (i == 0 || p->filter_jitter < min_jitter)
1153 min_jitter = p->filter_jitter;
1155 selection_jitter_sq = 0;
1156 for (j = 0; j < num_survivors; j++) {
1157 peer_t *q = survivor[j].p;
1158 selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
1160 if (i == 0 || selection_jitter_sq > max_selection_jitter) {
1161 max_selection_jitter = selection_jitter_sq;
1164 VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
1165 i, selection_jitter_sq);
1167 max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
1168 VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
1169 max_idx, max_selection_jitter, min_jitter);
1171 /* If the maximum selection jitter is less than the
1172 * minimum peer jitter, then tossing out more survivors
1173 * will not lower the minimum peer jitter, so we might
1176 if (max_selection_jitter < min_jitter) {
1177 VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
1178 max_selection_jitter, min_jitter, num_survivors);
1182 /* Delete survivor[max_idx] from the list
1183 * and go around again.
1185 VERB5 bb_error_msg("dropping survivor %d", max_idx);
1187 while (max_idx < num_survivors) {
1188 survivor[max_idx] = survivor[max_idx + 1];
1194 /* Combine the offsets of the clustering algorithm survivors
1195 * using a weighted average with weight determined by the root
1196 * distance. Compute the selection jitter as the weighted RMS
1197 * difference between the first survivor and the remaining
1198 * survivors. In some cases the inherent clock jitter can be
1199 * reduced by not using this algorithm, especially when frequent
1200 * clockhopping is involved. bbox: thus we don't do it.
1204 for (i = 0; i < num_survivors; i++) {
1206 x = root_distance(p);
1208 z += p->filter_offset / x;
1209 w += SQUARE(p->filter_offset - survivor[0].p->filter_offset) / x;
1211 //G.cluster_offset = z / y;
1212 //G.cluster_jitter = SQRT(w / y);
1215 /* Pick the best clock. If the old system peer is on the list
1216 * and at the same stratum as the first survivor on the list,
1217 * then don't do a clock hop. Otherwise, select the first
1218 * survivor on the list as the new system peer.
1221 if (G.last_update_peer
1222 && G.last_update_peer->lastpkt_stratum <= p->lastpkt_stratum
1224 /* Starting from 1 is ok here */
1225 for (i = 1; i < num_survivors; i++) {
1226 if (G.last_update_peer == survivor[i].p) {
1227 VERB4 bb_error_msg("keeping old synced peer");
1228 p = G.last_update_peer;
1233 G.last_update_peer = p;
1235 VERB3 bb_error_msg("selected peer %s filter_offset:%+f age:%f",
1238 G.cur_time - p->lastpkt_recv_time
1245 * Local clock discipline and its helpers
1248 set_new_values(int disc_state, double offset, double recv_time)
1250 /* Enter new state and set state variables. Note we use the time
1251 * of the last clock filter sample, which must be earlier than
1254 VERB3 bb_error_msg("disc_state=%d last update offset=%f recv_time=%f",
1255 disc_state, offset, recv_time);
1256 G.discipline_state = disc_state;
1257 G.last_update_offset = offset;
1258 G.last_update_recv_time = recv_time;
1260 /* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
1262 update_local_clock(peer_t *p)
1266 /* Note: can use G.cluster_offset instead: */
1267 double offset = p->filter_offset;
1268 double recv_time = p->lastpkt_recv_time;
1270 #if !USING_KERNEL_PLL_LOOP
1273 double since_last_update;
1274 double etemp, dtemp;
1276 abs_offset = fabs(offset);
1279 /* If needed, -S script can do it by looking at $offset
1280 * env var and killing parent */
1281 /* If the offset is too large, give up and go home */
1282 if (abs_offset > PANIC_THRESHOLD) {
1283 bb_error_msg_and_die("offset %f far too big, exiting", offset);
1287 /* If this is an old update, for instance as the result
1288 * of a system peer change, avoid it. We never use
1289 * an old sample or the same sample twice.
1291 if (recv_time <= G.last_update_recv_time) {
1292 VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it",
1293 G.last_update_recv_time, recv_time);
1294 return 0; /* "leave poll interval as is" */
1297 /* Clock state machine transition function. This is where the
1298 * action is and defines how the system reacts to large time
1299 * and frequency errors.
1301 since_last_update = recv_time - G.reftime;
1302 #if !USING_KERNEL_PLL_LOOP
1305 #if USING_INITIAL_FREQ_ESTIMATION
1306 if (G.discipline_state == STATE_FREQ) {
1307 /* Ignore updates until the stepout threshold */
1308 if (since_last_update < WATCH_THRESHOLD) {
1309 VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
1310 WATCH_THRESHOLD - since_last_update);
1311 return 0; /* "leave poll interval as is" */
1313 # if !USING_KERNEL_PLL_LOOP
1314 freq_drift = (offset - G.last_update_offset) / since_last_update;
1319 /* There are two main regimes: when the
1320 * offset exceeds the step threshold and when it does not.
1322 if (abs_offset > STEP_THRESHOLD) {
1323 switch (G.discipline_state) {
1325 /* The first outlyer: ignore it, switch to SPIK state */
1326 VERB3 bb_error_msg("offset:%+f - spike detected", offset);
1327 G.discipline_state = STATE_SPIK;
1328 return -1; /* "decrease poll interval" */
1331 /* Ignore succeeding outlyers until either an inlyer
1332 * is found or the stepout threshold is exceeded.
1334 if (since_last_update < WATCH_THRESHOLD) {
1335 VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains",
1336 WATCH_THRESHOLD - since_last_update);
1337 return -1; /* "decrease poll interval" */
1339 /* fall through: we need to step */
1342 /* Step the time and clamp down the poll interval.
1344 * In NSET state an initial frequency correction is
1345 * not available, usually because the frequency file has
1346 * not yet been written. Since the time is outside the
1347 * capture range, the clock is stepped. The frequency
1348 * will be set directly following the stepout interval.
1350 * In FSET state the initial frequency has been set
1351 * from the frequency file. Since the time is outside
1352 * the capture range, the clock is stepped immediately,
1353 * rather than after the stepout interval. Guys get
1354 * nervous if it takes 17 minutes to set the clock for
1357 * In SPIK state the stepout threshold has expired and
1358 * the phase is still above the step threshold. Note
1359 * that a single spike greater than the step threshold
1360 * is always suppressed, even at the longer poll
1363 VERB3 bb_error_msg("stepping time by %+f; poll_exp=MINPOLL", offset);
1365 if (option_mask32 & OPT_q) {
1366 /* We were only asked to set time once. Done. */
1370 G.polladj_count = 0;
1371 G.poll_exp = MINPOLL;
1372 G.stratum = MAXSTRAT;
1374 run_script("step", offset);
1376 #if USING_INITIAL_FREQ_ESTIMATION
1377 if (G.discipline_state == STATE_NSET) {
1378 set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
1379 return 1; /* "ok to increase poll interval" */
1382 abs_offset = offset = 0;
1383 set_new_values(STATE_SYNC, offset, recv_time);
1385 } else { /* abs_offset <= STEP_THRESHOLD */
1387 if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
1388 VERB3 bb_error_msg("small offset:%+f, disabling burst mode", offset);
1389 G.polladj_count = 0;
1390 G.poll_exp = MINPOLL;
1393 /* Compute the clock jitter as the RMS of exponentially
1394 * weighted offset differences. Used by the poll adjust code.
1396 etemp = SQUARE(G.discipline_jitter);
1397 dtemp = SQUARE(offset - G.last_update_offset);
1398 G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
1400 switch (G.discipline_state) {
1402 if (option_mask32 & OPT_q) {
1403 /* We were only asked to set time once.
1404 * The clock is precise enough, no need to step.
1408 #if USING_INITIAL_FREQ_ESTIMATION
1409 /* This is the first update received and the frequency
1410 * has not been initialized. The first thing to do
1411 * is directly measure the oscillator frequency.
1413 set_new_values(STATE_FREQ, offset, recv_time);
1415 set_new_values(STATE_SYNC, offset, recv_time);
1417 VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
1418 return 0; /* "leave poll interval as is" */
1420 #if 0 /* this is dead code for now */
1422 /* This is the first update and the frequency
1423 * has been initialized. Adjust the phase, but
1424 * don't adjust the frequency until the next update.
1426 set_new_values(STATE_SYNC, offset, recv_time);
1427 /* freq_drift remains 0 */
1431 #if USING_INITIAL_FREQ_ESTIMATION
1433 /* since_last_update >= WATCH_THRESHOLD, we waited enough.
1434 * Correct the phase and frequency and switch to SYNC state.
1435 * freq_drift was already estimated (see code above)
1437 set_new_values(STATE_SYNC, offset, recv_time);
1442 #if !USING_KERNEL_PLL_LOOP
1443 /* Compute freq_drift due to PLL and FLL contributions.
1445 * The FLL and PLL frequency gain constants
1446 * depend on the poll interval and Allan
1447 * intercept. The FLL is not used below one-half
1448 * the Allan intercept. Above that the loop gain
1449 * increases in steps to 1 / AVG.
1451 if ((1 << G.poll_exp) > ALLAN / 2) {
1452 etemp = FLL - G.poll_exp;
1455 freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp);
1457 /* For the PLL the integration interval
1458 * (numerator) is the minimum of the update
1459 * interval and poll interval. This allows
1460 * oversampling, but not undersampling.
1462 etemp = MIND(since_last_update, (1 << G.poll_exp));
1463 dtemp = (4 * PLL) << G.poll_exp;
1464 freq_drift += offset * etemp / SQUARE(dtemp);
1466 set_new_values(STATE_SYNC, offset, recv_time);
1469 if (G.stratum != p->lastpkt_stratum + 1) {
1470 G.stratum = p->lastpkt_stratum + 1;
1471 run_script("stratum", offset);
1475 if (G.discipline_jitter < G_precision_sec)
1476 G.discipline_jitter = G_precision_sec;
1477 G.offset_to_jitter_ratio = abs_offset / G.discipline_jitter;
1479 G.reftime = G.cur_time;
1480 G.ntp_status = p->lastpkt_status;
1481 G.refid = p->lastpkt_refid;
1482 G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
1483 dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(G.cluster_jitter));
1484 dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time) + abs_offset, MINDISP);
1485 G.rootdisp = p->lastpkt_rootdisp + dtemp;
1486 VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted);
1488 /* We are in STATE_SYNC now, but did not do adjtimex yet.
1489 * (Any other state does not reach this, they all return earlier)
1490 * By this time, freq_drift and offset are set
1491 * to values suitable for adjtimex.
1493 #if !USING_KERNEL_PLL_LOOP
1494 /* Calculate the new frequency drift and frequency stability (wander).
1495 * Compute the clock wander as the RMS of exponentially weighted
1496 * frequency differences. This is not used directly, but can,
1497 * along with the jitter, be a highly useful monitoring and
1500 dtemp = G.discipline_freq_drift + freq_drift;
1501 G.discipline_freq_drift = MAXD(MIND(MAXDRIFT, dtemp), -MAXDRIFT);
1502 etemp = SQUARE(G.discipline_wander);
1503 dtemp = SQUARE(dtemp);
1504 G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
1506 VERB3 bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
1507 G.discipline_freq_drift,
1508 (long)(G.discipline_freq_drift * 65536e6),
1510 G.discipline_wander);
1513 memset(&tmx, 0, sizeof(tmx));
1514 if (adjtimex(&tmx) < 0)
1515 bb_perror_msg_and_die("adjtimex");
1516 bb_error_msg("p adjtimex freq:%ld offset:%+ld status:0x%x tc:%ld",
1517 tmx.freq, tmx.offset, tmx.status, tmx.constant);
1520 memset(&tmx, 0, sizeof(tmx));
1522 //doesn't work, offset remains 0 (!) in kernel:
1523 //ntpd: set adjtimex freq:1786097 tmx.offset:77487
1524 //ntpd: prev adjtimex freq:1786097 tmx.offset:0
1525 //ntpd: cur adjtimex freq:1786097 tmx.offset:0
1526 tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET;
1527 /* 65536 is one ppm */
1528 tmx.freq = G.discipline_freq_drift * 65536e6;
1530 tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
1531 tmx.offset = (offset * 1000000); /* usec */
1532 tmx.status = STA_PLL;
1533 if (G.ntp_status & LI_PLUSSEC)
1534 tmx.status |= STA_INS;
1535 if (G.ntp_status & LI_MINUSSEC)
1536 tmx.status |= STA_DEL;
1538 tmx.constant = G.poll_exp - 4;
1540 * The below if statement should be unnecessary, but...
1541 * It looks like Linux kernel's PLL is far too gentle in changing
1542 * tmx.freq in response to clock offset. Offset keeps growing
1543 * and eventually we fall back to smaller poll intervals.
1544 * We can make correction more agressive (about x2) by supplying
1545 * PLL time constant which is one less than the real one.
1546 * To be on a safe side, let's do it only if offset is significantly
1547 * larger than jitter.
1549 if (tmx.constant > 0 && G.offset_to_jitter_ratio >= TIMECONST_HACK_GATE)
1552 //tmx.esterror = (uint32_t)(clock_jitter * 1e6);
1553 //tmx.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
1554 rc = adjtimex(&tmx);
1556 bb_perror_msg_and_die("adjtimex");
1557 /* NB: here kernel returns constant == G.poll_exp, not == G.poll_exp - 4.
1558 * Not sure why. Perhaps it is normal.
1560 VERB3 bb_error_msg("adjtimex:%d freq:%ld offset:%+ld status:0x%x",
1561 rc, tmx.freq, tmx.offset, tmx.status);
1562 G.kernel_freq_drift = tmx.freq / 65536;
1563 VERB2 bb_error_msg("update from:%s offset:%+f jitter:%f clock drift:%+.3fppm tc:%d",
1564 p->p_dotted, offset, G.discipline_jitter, (double)tmx.freq / 65536, (int)tmx.constant);
1566 return 1; /* "ok to increase poll interval" */
1571 * We've got a new reply packet from a peer, process it
1575 retry_interval(void)
1577 /* Local problem, want to retry soon */
1578 unsigned interval, r;
1579 interval = RETRY_INTERVAL;
1581 interval += r % (unsigned)(RETRY_INTERVAL / 4);
1582 VERB3 bb_error_msg("chose retry interval:%u", interval);
1586 poll_interval(int exponent)
1588 unsigned interval, r;
1589 exponent = G.poll_exp + exponent;
1592 interval = 1 << exponent;
1594 interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
1595 VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
1598 static NOINLINE void
1599 recv_and_process_peer_pkt(peer_t *p)
1604 double T1, T2, T3, T4;
1606 datapoint_t *datapoint;
1609 /* We can recvfrom here and check from.IP, but some multihomed
1610 * ntp servers reply from their *other IP*.
1611 * TODO: maybe we should check at least what we can: from.port == 123?
1613 size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
1615 bb_perror_msg("recv(%s) error", p->p_dotted);
1616 if (errno == EHOSTUNREACH || errno == EHOSTDOWN
1617 || errno == ENETUNREACH || errno == ENETDOWN
1618 || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
1621 //TODO: always do this?
1622 interval = retry_interval();
1623 goto set_next_and_close_sock;
1628 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1629 bb_error_msg("malformed packet received from %s", p->p_dotted);
1633 if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
1634 || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
1639 if ((msg.m_status & LI_ALARM) == LI_ALARM
1640 || msg.m_stratum == 0
1641 || msg.m_stratum > NTP_MAXSTRATUM
1643 // TODO: stratum 0 responses may have commands in 32-bit m_refid field:
1644 // "DENY", "RSTR" - peer does not like us at all
1645 // "RATE" - peer is overloaded, reduce polling freq
1646 interval = poll_interval(0);
1647 bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
1648 goto set_next_and_close_sock;
1651 // /* Verify valid root distance */
1652 // if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
1653 // return; /* invalid header values */
1655 p->lastpkt_status = msg.m_status;
1656 p->lastpkt_stratum = msg.m_stratum;
1657 p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
1658 p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
1659 p->lastpkt_refid = msg.m_refid;
1662 * From RFC 2030 (with a correction to the delay math):
1664 * Timestamp Name ID When Generated
1665 * ------------------------------------------------------------
1666 * Originate Timestamp T1 time request sent by client
1667 * Receive Timestamp T2 time request received by server
1668 * Transmit Timestamp T3 time reply sent by server
1669 * Destination Timestamp T4 time reply received by client
1671 * The roundtrip delay and local clock offset are defined as
1673 * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
1676 T2 = lfp_to_d(msg.m_rectime);
1677 T3 = lfp_to_d(msg.m_xmttime);
1680 p->lastpkt_recv_time = T4;
1682 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
1683 p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
1684 datapoint = &p->filter_datapoint[p->datapoint_idx];
1685 datapoint->d_recv_time = T4;
1686 datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
1687 /* The delay calculation is a special case. In cases where the
1688 * server and client clocks are running at different rates and
1689 * with very fast networks, the delay can appear negative. In
1690 * order to avoid violating the Principle of Least Astonishment,
1691 * the delay is clamped not less than the system precision.
1693 p->lastpkt_delay = (T4 - T1) - (T3 - T2);
1694 if (p->lastpkt_delay < G_precision_sec)
1695 p->lastpkt_delay = G_precision_sec;
1696 datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
1697 if (!p->reachable_bits) {
1698 /* 1st datapoint ever - replicate offset in every element */
1700 for (i = 0; i < NUM_DATAPOINTS; i++) {
1701 p->filter_datapoint[i].d_offset = datapoint->d_offset;
1705 p->reachable_bits |= 1;
1706 if ((MAX_VERBOSE && G.verbose) || (option_mask32 & OPT_w)) {
1707 bb_error_msg("reply from %s: offset:%+f delay:%f status:0x%02x strat:%d refid:0x%08x rootdelay:%f reach:0x%02x",
1709 datapoint->d_offset,
1714 p->lastpkt_rootdelay,
1716 /* not shown: m_ppoll, m_precision_exp, m_rootdisp,
1717 * m_reftime, m_orgtime, m_rectime, m_xmttime
1722 /* Muck with statictics and update the clock */
1723 filter_datapoints(p);
1724 q = select_and_cluster();
1728 if (!(option_mask32 & OPT_w)) {
1729 rc = update_local_clock(q);
1730 /* If drift is dangerously large, immediately
1731 * drop poll interval one step down.
1733 if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) {
1734 VERB3 bb_error_msg("offset:%+f > POLLDOWN_OFFSET", q->filter_offset);
1739 /* else: no peer selected, rc = -1: we want to poll more often */
1742 /* Adjust the poll interval by comparing the current offset
1743 * with the clock jitter. If the offset is less than
1744 * the clock jitter times a constant, then the averaging interval
1745 * is increased, otherwise it is decreased. A bit of hysteresis
1746 * helps calm the dance. Works best using burst mode.
1748 if (rc > 0 && G.offset_to_jitter_ratio <= POLLADJ_GATE) {
1749 /* was += G.poll_exp but it is a bit
1750 * too optimistic for my taste at high poll_exp's */
1751 G.polladj_count += MINPOLL;
1752 if (G.polladj_count > POLLADJ_LIMIT) {
1753 G.polladj_count = 0;
1754 if (G.poll_exp < MAXPOLL) {
1756 VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
1757 G.discipline_jitter, G.poll_exp);
1760 VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count);
1763 G.polladj_count -= G.poll_exp * 2;
1764 if (G.polladj_count < -POLLADJ_LIMIT || G.poll_exp >= BIGPOLL) {
1766 G.polladj_count = 0;
1767 if (G.poll_exp > MINPOLL) {
1771 /* Correct p->next_action_time in each peer
1772 * which waits for sending, so that they send earlier.
1773 * Old pp->next_action_time are on the order
1774 * of t + (1 << old_poll_exp) + small_random,
1775 * we simply need to subtract ~half of that.
1777 for (item = G.ntp_peers; item != NULL; item = item->link) {
1778 peer_t *pp = (peer_t *) item->data;
1780 pp->next_action_time -= (1 << G.poll_exp);
1782 VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
1783 G.discipline_jitter, G.poll_exp);
1786 VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count);
1791 /* Decide when to send new query for this peer */
1792 interval = poll_interval(0);
1794 set_next_and_close_sock:
1795 set_next(p, interval);
1796 /* We do not expect any more packets from this peer for now.
1797 * Closing the socket informs kernel about it.
1798 * We open a new socket when we send a new query.
1806 #if ENABLE_FEATURE_NTPD_SERVER
1807 static NOINLINE void
1808 recv_and_process_client_pkt(void /*int fd*/)
1812 len_and_sockaddr *to;
1813 struct sockaddr *from;
1815 uint8_t query_status;
1816 l_fixedpt_t query_xmttime;
1818 to = get_sock_lsa(G.listen_fd);
1819 from = xzalloc(to->len);
1821 size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
1822 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1825 if (errno == EAGAIN)
1827 bb_perror_msg_and_die("recv");
1829 addr = xmalloc_sockaddr2dotted_noport(from);
1830 bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
1835 query_status = msg.m_status;
1836 query_xmttime = msg.m_xmttime;
1838 /* Build a reply packet */
1839 memset(&msg, 0, sizeof(msg));
1840 msg.m_status = G.stratum < MAXSTRAT ? G.ntp_status : LI_ALARM;
1841 msg.m_status |= (query_status & VERSION_MASK);
1842 msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
1843 MODE_SERVER : MODE_SYM_PAS;
1844 msg.m_stratum = G.stratum;
1845 msg.m_ppoll = G.poll_exp;
1846 msg.m_precision_exp = G_precision_exp;
1847 /* this time was obtained between poll() and recv() */
1848 msg.m_rectime = d_to_lfp(G.cur_time);
1849 msg.m_xmttime = d_to_lfp(gettime1900d()); /* this instant */
1850 if (G.peer_cnt == 0) {
1851 /* we have no peers: "stratum 1 server" mode. reftime = our own time */
1852 G.reftime = G.cur_time;
1854 msg.m_reftime = d_to_lfp(G.reftime);
1855 msg.m_orgtime = query_xmttime;
1856 msg.m_rootdelay = d_to_sfp(G.rootdelay);
1857 //simple code does not do this, fix simple code!
1858 msg.m_rootdisp = d_to_sfp(G.rootdisp);
1859 //version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
1860 msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3;
1862 /* We reply from the local address packet was sent to,
1863 * this makes to/from look swapped here: */
1864 do_sendto(G.listen_fd,
1865 /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
1874 /* Upstream ntpd's options:
1876 * -4 Force DNS resolution of host names to the IPv4 namespace.
1877 * -6 Force DNS resolution of host names to the IPv6 namespace.
1878 * -a Require cryptographic authentication for broadcast client,
1879 * multicast client and symmetric passive associations.
1880 * This is the default.
1881 * -A Do not require cryptographic authentication for broadcast client,
1882 * multicast client and symmetric passive associations.
1883 * This is almost never a good idea.
1884 * -b Enable the client to synchronize to broadcast servers.
1886 * Specify the name and path of the configuration file,
1887 * default /etc/ntp.conf
1888 * -d Specify debugging mode. This option may occur more than once,
1889 * with each occurrence indicating greater detail of display.
1891 * Specify debugging level directly.
1893 * Specify the name and path of the frequency file.
1894 * This is the same operation as the "driftfile FILE"
1895 * configuration command.
1896 * -g Normally, ntpd exits with a message to the system log
1897 * if the offset exceeds the panic threshold, which is 1000 s
1898 * by default. This option allows the time to be set to any value
1899 * without restriction; however, this can happen only once.
1900 * If the threshold is exceeded after that, ntpd will exit
1901 * with a message to the system log. This option can be used
1902 * with the -q and -x options. See the tinker command for other options.
1904 * Chroot the server to the directory jaildir. This option also implies
1905 * that the server attempts to drop root privileges at startup
1906 * (otherwise, chroot gives very little additional security).
1907 * You may need to also specify a -u option.
1909 * Specify the name and path of the symmetric key file,
1910 * default /etc/ntp/keys. This is the same operation
1911 * as the "keys FILE" configuration command.
1913 * Specify the name and path of the log file. The default
1914 * is the system log file. This is the same operation as
1915 * the "logfile FILE" configuration command.
1916 * -L Do not listen to virtual IPs. The default is to listen.
1918 * -N To the extent permitted by the operating system,
1919 * run the ntpd at the highest priority.
1921 * Specify the name and path of the file used to record the ntpd
1922 * process ID. This is the same operation as the "pidfile FILE"
1923 * configuration command.
1925 * To the extent permitted by the operating system,
1926 * run the ntpd at the specified priority.
1927 * -q Exit the ntpd just after the first time the clock is set.
1928 * This behavior mimics that of the ntpdate program, which is
1929 * to be retired. The -g and -x options can be used with this option.
1930 * Note: The kernel time discipline is disabled with this option.
1932 * Specify the default propagation delay from the broadcast/multicast
1933 * server to this client. This is necessary only if the delay
1934 * cannot be computed automatically by the protocol.
1936 * Specify the directory path for files created by the statistics
1937 * facility. This is the same operation as the "statsdir DIR"
1938 * configuration command.
1940 * Add a key number to the trusted key list. This option can occur
1943 * Specify a user, and optionally a group, to switch to.
1946 * Add a system variable listed by default.
1947 * -x Normally, the time is slewed if the offset is less than the step
1948 * threshold, which is 128 ms by default, and stepped if above
1949 * the threshold. This option sets the threshold to 600 s, which is
1950 * well within the accuracy window to set the clock manually.
1951 * Note: since the slew rate of typical Unix kernels is limited
1952 * to 0.5 ms/s, each second of adjustment requires an amortization
1953 * interval of 2000 s. Thus, an adjustment as much as 600 s
1954 * will take almost 14 days to complete. This option can be used
1955 * with the -g and -q options. See the tinker command for other options.
1956 * Note: The kernel time discipline is disabled with this option.
1959 /* By doing init in a separate function we decrease stack usage
1962 static NOINLINE void ntp_init(char **argv)
1970 bb_error_msg_and_die(bb_msg_you_must_be_root);
1972 /* Set some globals */
1973 G.stratum = MAXSTRAT;
1975 G.poll_exp = BURSTPOLL; /* speeds up initial sync */
1976 G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
1980 opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
1981 opts = getopt32(argv,
1983 "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
1985 "46aAbgL", /* compat, ignored */
1986 &peers, &G.script_name, &G.verbose);
1987 if (!(opts & (OPT_p|OPT_l)))
1989 // if (opts & OPT_x) /* disable stepping, only slew is allowed */
1990 // G.time_was_stepped = 1;
1993 add_peers(llist_pop(&peers));
1995 /* -l but no peers: "stratum 1 server" mode */
1998 if (!(opts & OPT_n)) {
1999 bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
2000 logmode = LOGMODE_NONE;
2002 #if ENABLE_FEATURE_NTPD_SERVER
2005 G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
2006 socket_want_pktinfo(G.listen_fd);
2007 setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
2010 /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
2012 setpriority(PRIO_PROCESS, 0, -15);
2014 /* If network is up, syncronization occurs in ~10 seconds.
2015 * We give "ntpd -q" 10 seconds to get first reply,
2016 * then another 50 seconds to finish syncing.
2018 * I tested ntpd 4.2.6p1 and apparently it never exits
2019 * (will try forever), but it does not feel right.
2020 * The goal of -q is to act like ntpdate: set time
2021 * after a reasonably small period of polling, or fail.
2024 option_mask32 |= OPT_qq;
2041 int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
2042 int ntpd_main(int argc UNUSED_PARAM, char **argv)
2050 memset(&G, 0, sizeof(G));
2051 SET_PTR_TO_GLOBALS(&G);
2055 /* If ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
2056 cnt = G.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
2057 idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
2058 pfd = xzalloc(sizeof(pfd[0]) * cnt);
2060 /* Countdown: we never sync before we sent INITIAL_SAMPLES+1
2061 * packets to each peer.
2062 * NB: if some peer is not responding, we may end up sending
2063 * fewer packets to it and more to other peers.
2064 * NB2: sync usually happens using INITIAL_SAMPLES packets,
2065 * since last reply does not come back instantaneously.
2067 cnt = G.peer_cnt * (INITIAL_SAMPLES + 1);
2069 while (!bb_got_signal) {
2075 /* Nothing between here and poll() blocks for any significant time */
2077 nextaction = G.cur_time + 3600;
2080 #if ENABLE_FEATURE_NTPD_SERVER
2081 if (G.listen_fd != -1) {
2082 pfd[0].fd = G.listen_fd;
2083 pfd[0].events = POLLIN;
2087 /* Pass over peer list, send requests, time out on receives */
2088 for (item = G.ntp_peers; item != NULL; item = item->link) {
2089 peer_t *p = (peer_t *) item->data;
2091 if (p->next_action_time <= G.cur_time) {
2092 if (p->p_fd == -1) {
2093 /* Time to send new req */
2095 G.initial_poll_complete = 1;
2097 send_query_to_peer(p);
2099 /* Timed out waiting for reply */
2102 timeout = poll_interval(-2); /* -2: try a bit sooner */
2103 bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
2104 p->p_dotted, p->reachable_bits, timeout);
2105 set_next(p, timeout);
2109 if (p->next_action_time < nextaction)
2110 nextaction = p->next_action_time;
2113 /* Wait for reply from this peer */
2114 pfd[i].fd = p->p_fd;
2115 pfd[i].events = POLLIN;
2121 timeout = nextaction - G.cur_time;
2124 timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
2126 /* Here we may block */
2128 if (i > (ENABLE_FEATURE_NTPD_SERVER && G.listen_fd != -1)) {
2129 /* We wait for at least one reply.
2130 * Poll for it, without wasting time for message.
2131 * Since replies often come under 1 second, this also
2132 * reduces clutter in logs.
2134 nfds = poll(pfd, i, 1000);
2140 bb_error_msg("poll:%us sockets:%u interval:%us", timeout, i, 1 << G.poll_exp);
2142 nfds = poll(pfd, i, timeout * 1000);
2144 gettime1900d(); /* sets G.cur_time */
2146 if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
2147 /* Useful for updating battery-backed RTC and such */
2148 run_script("periodic", G.last_update_offset);
2149 gettime1900d(); /* sets G.cur_time */
2154 /* Process any received packets */
2156 #if ENABLE_FEATURE_NTPD_SERVER
2157 if (G.listen_fd != -1) {
2158 if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
2160 recv_and_process_client_pkt(/*G.listen_fd*/);
2161 gettime1900d(); /* sets G.cur_time */
2166 for (; nfds != 0 && j < i; j++) {
2167 if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
2169 * At init, alarm was set to 10 sec.
2170 * Now we did get a reply.
2171 * Increase timeout to 50 seconds to finish syncing.
2173 if (option_mask32 & OPT_qq) {
2174 option_mask32 &= ~OPT_qq;
2178 recv_and_process_peer_pkt(idx2peer[j]);
2179 gettime1900d(); /* sets G.cur_time */
2182 } /* while (!bb_got_signal) */
2184 kill_myself_with_sig(bb_got_signal);
2192 /*** openntpd-4.6 uses only adjtime, not adjtimex ***/
2194 /*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/
2198 direct_freq(double fp_offset)
2202 * If the kernel is enabled, we need the residual offset to
2203 * calculate the frequency correction.
2205 if (pll_control && kern_enable) {
2206 memset(&ntv, 0, sizeof(ntv));
2209 clock_offset = ntv.offset / 1e9;
2210 #else /* STA_NANO */
2211 clock_offset = ntv.offset / 1e6;
2212 #endif /* STA_NANO */
2213 drift_comp = FREQTOD(ntv.freq);
2215 #endif /* KERNEL_PLL */
2216 set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp);
2222 set_freq(double freq) /* frequency update */
2230 * If the kernel is enabled, update the kernel frequency.
2232 if (pll_control && kern_enable) {
2233 memset(&ntv, 0, sizeof(ntv));
2234 ntv.modes = MOD_FREQUENCY;
2235 ntv.freq = DTOFREQ(drift_comp);
2237 snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6);
2238 report_event(EVNT_FSET, NULL, tbuf);
2240 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2241 report_event(EVNT_FSET, NULL, tbuf);
2243 #else /* KERNEL_PLL */
2244 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2245 report_event(EVNT_FSET, NULL, tbuf);
2246 #endif /* KERNEL_PLL */
2255 * This code segment works when clock adjustments are made using
2256 * precision time kernel support and the ntp_adjtime() system
2257 * call. This support is available in Solaris 2.6 and later,
2258 * Digital Unix 4.0 and later, FreeBSD, Linux and specially
2259 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
2260 * DECstation 5000/240 and Alpha AXP, additional kernel
2261 * modifications provide a true microsecond clock and nanosecond
2262 * clock, respectively.
2264 * Important note: The kernel discipline is used only if the
2265 * step threshold is less than 0.5 s, as anything higher can
2266 * lead to overflow problems. This might occur if some misguided
2267 * lad set the step threshold to something ridiculous.
2269 if (pll_control && kern_enable) {
2271 #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST)
2274 * We initialize the structure for the ntp_adjtime()
2275 * system call. We have to convert everything to
2276 * microseconds or nanoseconds first. Do not update the
2277 * system variables if the ext_enable flag is set. In
2278 * this case, the external clock driver will update the
2279 * variables, which will be read later by the local
2280 * clock driver. Afterwards, remember the time and
2281 * frequency offsets for jitter and stability values and
2282 * to update the frequency file.
2284 memset(&ntv, 0, sizeof(ntv));
2286 ntv.modes = MOD_STATUS;
2289 ntv.modes = MOD_BITS | MOD_NANO;
2290 #else /* STA_NANO */
2291 ntv.modes = MOD_BITS;
2292 #endif /* STA_NANO */
2293 if (clock_offset < 0)
2298 ntv.offset = (int32)(clock_offset * 1e9 + dtemp);
2299 ntv.constant = sys_poll;
2300 #else /* STA_NANO */
2301 ntv.offset = (int32)(clock_offset * 1e6 + dtemp);
2302 ntv.constant = sys_poll - 4;
2303 #endif /* STA_NANO */
2304 ntv.esterror = (u_int32)(clock_jitter * 1e6);
2305 ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
2306 ntv.status = STA_PLL;
2309 * Enable/disable the PPS if requested.
2312 if (!(pll_status & STA_PPSTIME))
2313 report_event(EVNT_KERN,
2314 NULL, "PPS enabled");
2315 ntv.status |= STA_PPSTIME | STA_PPSFREQ;
2317 if (pll_status & STA_PPSTIME)
2318 report_event(EVNT_KERN,
2319 NULL, "PPS disabled");
2320 ntv.status &= ~(STA_PPSTIME |
2323 if (sys_leap == LEAP_ADDSECOND)
2324 ntv.status |= STA_INS;
2325 else if (sys_leap == LEAP_DELSECOND)
2326 ntv.status |= STA_DEL;
2330 * Pass the stuff to the kernel. If it squeals, turn off
2331 * the pps. In any case, fetch the kernel offset,
2332 * frequency and jitter.
2334 if (ntp_adjtime(&ntv) == TIME_ERROR) {
2335 if (!(ntv.status & STA_PPSSIGNAL))
2336 report_event(EVNT_KERN, NULL,
2339 pll_status = ntv.status;
2341 clock_offset = ntv.offset / 1e9;
2342 #else /* STA_NANO */
2343 clock_offset = ntv.offset / 1e6;
2344 #endif /* STA_NANO */
2345 clock_frequency = FREQTOD(ntv.freq);
2348 * If the kernel PPS is lit, monitor its performance.
2350 if (ntv.status & STA_PPSTIME) {
2352 clock_jitter = ntv.jitter / 1e9;
2353 #else /* STA_NANO */
2354 clock_jitter = ntv.jitter / 1e6;
2355 #endif /* STA_NANO */
2358 #if defined(STA_NANO) && NTP_API == 4
2360 * If the TAI changes, update the kernel TAI.
2362 if (loop_tai != sys_tai) {
2364 ntv.modes = MOD_TAI;
2365 ntv.constant = sys_tai;
2368 #endif /* STA_NANO */
2370 #endif /* KERNEL_PLL */