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 #define BIGPOLL 10 /* drop to lower poll at any trouble (10: 17 min) */
111 #define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h). std ntpd uses 17 */
112 /* Actively lower poll when we see such big offsets.
113 * With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively
114 * if offset increases over ~0.04 sec */
115 #define POLLDOWN_OFFSET (STEP_THRESHOLD / 3)
116 #define MINDISP 0.01 /* minimum dispersion (sec) */
117 #define MAXDISP 16 /* maximum dispersion (sec) */
118 #define MAXSTRAT 16 /* maximum stratum (infinity metric) */
119 #define MAXDIST 1 /* distance threshold (sec) */
120 #define MIN_SELECTED 1 /* minimum intersection survivors */
121 #define MIN_CLUSTERED 3 /* minimum cluster survivors */
123 #define MAXDRIFT 0.000500 /* frequency drift we can correct (500 PPM) */
125 /* Poll-adjust threshold.
126 * When we see that offset is small enough compared to discipline jitter,
127 * we grow a counter: += MINPOLL. When it goes over POLLADJ_LIMIT,
128 * we poll_exp++. If offset isn't small, counter -= poll_exp*2,
129 * and when it goes below -POLLADJ_LIMIT, we poll_exp--
130 * (bumped from 30 to 40 since otherwise I often see poll_exp going *2* steps down)
132 #define POLLADJ_LIMIT 40
133 /* If offset < POLLADJ_GATE * discipline_jitter, then we can increase
134 * poll interval (we think we can't improve timekeeping
135 * by staying at smaller poll).
137 #define POLLADJ_GATE 4
138 /* Compromise Allan intercept (sec). doc uses 1500, std ntpd uses 512 */
142 /* FLL loop gain [why it depends on MAXPOLL??] */
143 #define FLL (MAXPOLL + 1)
144 /* Parameter averaging constant */
153 NTP_MSGSIZE_NOAUTH = 48,
154 NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
157 MODE_MASK = (7 << 0),
158 VERSION_MASK = (7 << 3),
162 /* Leap Second Codes (high order two bits of m_status) */
163 LI_NOWARNING = (0 << 6), /* no warning */
164 LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
165 LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
166 LI_ALARM = (3 << 6), /* alarm condition */
169 MODE_RES0 = 0, /* reserved */
170 MODE_SYM_ACT = 1, /* symmetric active */
171 MODE_SYM_PAS = 2, /* symmetric passive */
172 MODE_CLIENT = 3, /* client */
173 MODE_SERVER = 4, /* server */
174 MODE_BROADCAST = 5, /* broadcast */
175 MODE_RES1 = 6, /* reserved for NTP control message */
176 MODE_RES2 = 7, /* reserved for private use */
179 //TODO: better base selection
180 #define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
182 #define NUM_DATAPOINTS 8
195 uint8_t m_status; /* status of local clock and leap info */
197 uint8_t m_ppoll; /* poll value */
198 int8_t m_precision_exp;
199 s_fixedpt_t m_rootdelay;
200 s_fixedpt_t m_rootdisp;
202 l_fixedpt_t m_reftime;
203 l_fixedpt_t m_orgtime;
204 l_fixedpt_t m_rectime;
205 l_fixedpt_t m_xmttime;
207 uint8_t m_digest[NTP_DIGESTSIZE];
217 len_and_sockaddr *p_lsa;
219 /* when to send new query (if p_fd == -1)
220 * or when receive times out (if p_fd >= 0): */
223 uint32_t lastpkt_refid;
224 uint8_t lastpkt_status;
225 uint8_t lastpkt_stratum;
226 uint8_t reachable_bits;
227 double next_action_time;
229 double lastpkt_recv_time;
230 double lastpkt_delay;
231 double lastpkt_rootdelay;
232 double lastpkt_rootdisp;
233 /* produced by filter algorithm: */
234 double filter_offset;
235 double filter_dispersion;
236 double filter_jitter;
237 datapoint_t filter_datapoint[NUM_DATAPOINTS];
238 /* last sent packet: */
243 #define USING_KERNEL_PLL_LOOP 1
244 #define USING_INITIAL_FREQ_ESTIMATION 0
251 /* Insert new options above this line. */
252 /* Non-compat options: */
256 OPT_l = (1 << 7) * ENABLE_FEATURE_NTPD_SERVER,
257 /* We hijack some bits for other purposes */
263 /* total round trip delay to currently selected reference clock */
265 /* reference timestamp: time when the system clock was last set or corrected */
267 /* total dispersion to currently selected reference clock */
270 double last_script_run;
273 #if ENABLE_FEATURE_NTPD_SERVER
278 /* refid: 32-bit code identifying the particular server or reference clock
279 * in stratum 0 packets this is a four-character ASCII string,
280 * called the kiss code, used for debugging and monitoring
281 * in stratum 1 packets this is a four-character ASCII string
282 * assigned to the reference clock by IANA. Example: "GPS "
283 * in stratum 2+ packets, it's IPv4 address or 4 first bytes
284 * of MD5 hash of IPv6
288 /* precision is defined as the larger of the resolution and time to
289 * read the clock, in log2 units. For instance, the precision of a
290 * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
291 * system clock hardware representation is to the nanosecond.
293 * Delays, jitters of various kinds are clamped down to precision.
295 * If precision_sec is too large, discipline_jitter gets clamped to it
296 * and if offset is smaller than discipline_jitter * POLLADJ_GATE, poll
297 * interval grows even though we really can benefit from staying at
298 * smaller one, collecting non-lagged datapoits and correcting offset.
299 * (Lagged datapoits exist when poll_exp is large but we still have
300 * systematic offset error - the time distance between datapoints
301 * is significant and older datapoints have smaller offsets.
302 * This makes our offset estimation a bit smaller than reality)
303 * Due to this effect, setting G_precision_sec close to
304 * STEP_THRESHOLD isn't such a good idea - offsets may grow
305 * too big and we will step. I observed it with -6.
307 * OTOH, setting precision_sec far too small would result in futile
308 * attempts to syncronize to an unachievable precision.
310 * -6 is 1/64 sec, -7 is 1/128 sec and so on.
311 * -8 is 1/256 ~= 0.003906 (worked well for me --vda)
312 * -9 is 1/512 ~= 0.001953 (let's try this for some time)
314 #define G_precision_exp -9
316 * G_precision_exp is used only for construction outgoing packets.
317 * It's ok to set G_precision_sec to a slightly different value
318 * (One which is "nicer looking" in logs).
319 * Exact value would be (1.0 / (1 << (- G_precision_exp))):
321 #define G_precision_sec 0.002
323 /* Bool. After set to 1, never goes back to 0: */
324 smallint initial_poll_complete;
326 #define STATE_NSET 0 /* initial state, "nothing is set" */
327 //#define STATE_FSET 1 /* frequency set from file */
328 #define STATE_SPIK 2 /* spike detected */
329 //#define STATE_FREQ 3 /* initial frequency */
330 #define STATE_SYNC 4 /* clock synchronized (normal operation) */
331 uint8_t discipline_state; // doc calls it c.state
332 uint8_t poll_exp; // s.poll
333 int polladj_count; // c.count
334 long kernel_freq_drift;
335 peer_t *last_update_peer;
336 double last_update_offset; // c.last
337 double last_update_recv_time; // s.t
338 double discipline_jitter; // c.jitter
339 //double cluster_offset; // s.offset
340 //double cluster_jitter; // s.jitter
341 #if !USING_KERNEL_PLL_LOOP
342 double discipline_freq_drift; // c.freq
343 /* Maybe conditionally calculate wander? it's used only for logging */
344 double discipline_wander; // c.wander
347 #define G (*ptr_to_globals)
349 static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
352 #define VERB1 if (MAX_VERBOSE && G.verbose)
353 #define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
354 #define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
355 #define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
356 #define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
359 static double LOG2D(int a)
362 return 1.0 / (1UL << -a);
365 static ALWAYS_INLINE double SQUARE(double x)
369 static ALWAYS_INLINE double MAXD(double a, double b)
375 static ALWAYS_INLINE double MIND(double a, double b)
381 static NOINLINE double my_SQRT(double X)
388 double Xhalf = X * 0.5;
390 /* Fast and good approximation to 1/sqrt(X), black magic */
392 /*v.i = 0x5f3759df - (v.i >> 1);*/
393 v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
394 invsqrt = v.f; /* better than 0.2% accuracy */
396 /* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
397 * f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
399 * f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
400 * x1 = x0 - (X*x0*x0*x0/2 - x0/2) = 1.5*x0 - X*x0*x0*x0/2 = x0*(1.5 - (X/2)*x0*x0)
402 invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
403 /* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
404 /* With 4 iterations, more than half results will be exact,
405 * at 6th iterations result stabilizes with about 72% results exact.
406 * We are well satisfied with 0.05% accuracy.
409 return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
411 static ALWAYS_INLINE double SQRT(double X)
413 /* If this arch doesn't use IEEE 754 floats, fall back to using libm */
414 if (sizeof(float) != 4)
417 /* This avoids needing libm, saves about 0.5k on x86-32 */
425 gettimeofday(&tv, NULL); /* never fails */
426 G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
431 d_to_tv(double d, struct timeval *tv)
433 tv->tv_sec = (long)d;
434 tv->tv_usec = (d - tv->tv_sec) * 1000000;
438 lfp_to_d(l_fixedpt_t lfp)
441 lfp.int_partl = ntohl(lfp.int_partl);
442 lfp.fractionl = ntohl(lfp.fractionl);
443 ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
447 sfp_to_d(s_fixedpt_t sfp)
450 sfp.int_parts = ntohs(sfp.int_parts);
451 sfp.fractions = ntohs(sfp.fractions);
452 ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
455 #if ENABLE_FEATURE_NTPD_SERVER
460 lfp.int_partl = (uint32_t)d;
461 lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
462 lfp.int_partl = htonl(lfp.int_partl);
463 lfp.fractionl = htonl(lfp.fractionl);
470 sfp.int_parts = (uint16_t)d;
471 sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
472 sfp.int_parts = htons(sfp.int_parts);
473 sfp.fractions = htons(sfp.fractions);
479 dispersion(const datapoint_t *dp)
481 return dp->d_dispersion + FREQ_TOLERANCE * (G.cur_time - dp->d_recv_time);
485 root_distance(peer_t *p)
487 /* The root synchronization distance is the maximum error due to
488 * all causes of the local clock relative to the primary server.
489 * It is defined as half the total delay plus total dispersion
492 return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2
493 + p->lastpkt_rootdisp
494 + p->filter_dispersion
495 + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time)
500 set_next(peer_t *p, unsigned t)
502 p->next_action_time = G.cur_time + t;
506 * Peer clock filter and its helpers
509 filter_datapoints(peer_t *p)
513 double minoff, maxoff, wavg, sum, w;
514 double x = x; /* for compiler */
515 double oldest_off = oldest_off;
516 double oldest_age = oldest_age;
517 double newest_off = newest_off;
518 double newest_age = newest_age;
520 minoff = maxoff = p->filter_datapoint[0].d_offset;
521 for (i = 1; i < NUM_DATAPOINTS; i++) {
522 if (minoff > p->filter_datapoint[i].d_offset)
523 minoff = p->filter_datapoint[i].d_offset;
524 if (maxoff < p->filter_datapoint[i].d_offset)
525 maxoff = p->filter_datapoint[i].d_offset;
528 idx = p->datapoint_idx; /* most recent datapoint */
530 * Drop two outliers and take weighted average of the rest:
531 * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
532 * we use older6/32, not older6/64 since sum of weights should be 1:
533 * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
539 * filter_dispersion = \ -------------
546 for (i = 0; i < NUM_DATAPOINTS; i++) {
548 bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
550 p->filter_datapoint[idx].d_offset,
551 p->filter_datapoint[idx].d_dispersion, dispersion(&p->filter_datapoint[idx]),
552 G.cur_time - p->filter_datapoint[idx].d_recv_time,
553 (minoff == p->filter_datapoint[idx].d_offset || maxoff == p->filter_datapoint[idx].d_offset)
554 ? " (outlier by offset)" : ""
558 sum += dispersion(&p->filter_datapoint[idx]) / (2 << i);
560 if (minoff == p->filter_datapoint[idx].d_offset) {
561 minoff -= 1; /* so that we don't match it ever again */
563 if (maxoff == p->filter_datapoint[idx].d_offset) {
566 oldest_off = p->filter_datapoint[idx].d_offset;
567 oldest_age = G.cur_time - p->filter_datapoint[idx].d_recv_time;
570 newest_off = oldest_off;
571 newest_age = oldest_age;
578 idx = (idx - 1) & (NUM_DATAPOINTS - 1);
580 p->filter_dispersion = sum;
581 wavg += x; /* add another older6/64 to form older6/32 */
582 /* Fix systematic underestimation with large poll intervals.
583 * Imagine that we still have a bit of uncorrected drift,
584 * and poll interval is big (say, 100 sec). Offsets form a progression:
585 * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
586 * The algorithm above drops 0.0 and 0.7 as outliers,
587 * and then we have this estimation, ~25% off from 0.7:
588 * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
590 x = oldest_age - newest_age;
592 x = newest_age / x; /* in above example, 100 / (600 - 100) */
593 if (x < 1) { /* paranoia check */
594 x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
598 p->filter_offset = wavg;
600 /* +----- -----+ ^ 1/2
604 * filter_jitter = | --- * / (avg-offset_j) |
608 * where n is the number of valid datapoints in the filter (n > 1);
609 * if filter_jitter < precision then filter_jitter = precision
612 for (i = 0; i < NUM_DATAPOINTS; i++) {
613 sum += SQUARE(wavg - p->filter_datapoint[i].d_offset);
615 sum = SQRT(sum / NUM_DATAPOINTS);
616 p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
618 VERB3 bb_error_msg("filter offset:%+f(corr:%e) disp:%f jitter:%f",
620 p->filter_dispersion,
625 reset_peer_stats(peer_t *p, double offset)
628 bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
630 for (i = 0; i < NUM_DATAPOINTS; i++) {
632 p->filter_datapoint[i].d_recv_time += offset;
633 if (p->filter_datapoint[i].d_offset != 0) {
634 p->filter_datapoint[i].d_offset -= offset;
635 //bb_error_msg("p->filter_datapoint[%d].d_offset %f -> %f",
637 // p->filter_datapoint[i].d_offset + offset,
638 // p->filter_datapoint[i].d_offset);
641 p->filter_datapoint[i].d_recv_time = G.cur_time;
642 p->filter_datapoint[i].d_offset = 0;
643 p->filter_datapoint[i].d_dispersion = MAXDISP;
647 p->lastpkt_recv_time += offset;
649 p->reachable_bits = 0;
650 p->lastpkt_recv_time = G.cur_time;
652 filter_datapoints(p); /* recalc p->filter_xxx */
653 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
661 p = xzalloc(sizeof(*p));
662 p->p_lsa = xhost2sockaddr(s, 123);
663 p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
665 p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
666 p->next_action_time = G.cur_time; /* = set_next(p, 0); */
667 reset_peer_stats(p, 16 * STEP_THRESHOLD);
669 llist_add_to(&G.ntp_peers, p);
675 const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
676 msg_t *msg, ssize_t len)
682 ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
684 ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
687 bb_perror_msg("send failed");
694 send_query_to_peer(peer_t *p)
696 /* Why do we need to bind()?
697 * See what happens when we don't bind:
699 * socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
700 * setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
701 * gettimeofday({1259071266, 327885}, NULL) = 0
702 * sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
703 * ^^^ we sent it from some source port picked by kernel.
704 * time(NULL) = 1259071266
705 * write(2, "ntpd: entering poll 15 secs\n", 28) = 28
706 * poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
707 * recv(3, "yyy", 68, MSG_DONTWAIT) = 48
708 * ^^^ this recv will receive packets to any local port!
710 * Uncomment this and use strace to see it in action:
712 #define PROBE_LOCAL_ADDR /* { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } */
716 len_and_sockaddr *local_lsa;
718 family = p->p_lsa->u.sa.sa_family;
719 p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
720 /* local_lsa has "null" address and port 0 now.
721 * bind() ensures we have a *particular port* selected by kernel
722 * and remembered in p->p_fd, thus later recv(p->p_fd)
723 * receives only packets sent to this port.
726 xbind(fd, &local_lsa->u.sa, local_lsa->len);
728 #if ENABLE_FEATURE_IPV6
729 if (family == AF_INET)
731 setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
736 * Send out a random 64-bit number as our transmit time. The NTP
737 * server will copy said number into the originate field on the
738 * response that it sends us. This is totally legal per the SNTP spec.
740 * The impact of this is two fold: we no longer send out the current
741 * system time for the world to see (which may aid an attacker), and
742 * it gives us a (not very secure) way of knowing that we're not
743 * getting spoofed by an attacker that can't capture our traffic
744 * but can spoof packets from the NTP server we're communicating with.
746 * Save the real transmit timestamp locally.
748 p->p_xmt_msg.m_xmttime.int_partl = random();
749 p->p_xmt_msg.m_xmttime.fractionl = random();
750 p->p_xmttime = gettime1900d();
752 if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
753 &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
757 set_next(p, RETRY_INTERVAL);
761 p->reachable_bits <<= 1;
762 VERB1 bb_error_msg("sent query to %s", p->p_dotted);
763 set_next(p, RESPONSE_INTERVAL);
767 /* Note that there is no provision to prevent several run_scripts
768 * to be done in quick succession. In fact, it happens rather often
769 * if initial syncronization results in a step.
770 * You will see "step" and then "stratum" script runs, sometimes
771 * as close as only 0.002 seconds apart.
772 * Script should be ready to deal with this.
774 static void run_script(const char *action, double offset)
777 char *env1, *env2, *env3, *env4;
782 argv[0] = (char*) G.script_name;
783 argv[1] = (char*) action;
786 VERB1 bb_error_msg("executing '%s %s'", G.script_name, action);
788 env1 = xasprintf("%s=%u", "stratum", G.stratum);
790 env2 = xasprintf("%s=%ld", "freq_drift_ppm", G.kernel_freq_drift);
792 env3 = xasprintf("%s=%u", "poll_interval", 1 << G.poll_exp);
794 env4 = xasprintf("%s=%f", "offset", offset);
796 /* Other items of potential interest: selected peer,
797 * rootdelay, reftime, rootdisp, refid, ntp_status,
798 * last_update_offset, last_update_recv_time, discipline_jitter,
799 * how many peers have reachable_bits = 0?
802 /* Don't want to wait: it may run hwclock --systohc, and that
803 * may take some time (seconds): */
804 /*spawn_and_wait(argv);*/
808 unsetenv("freq_drift_ppm");
809 unsetenv("poll_interval");
816 G.last_script_run = G.cur_time;
820 step_time(double offset)
824 struct timeval tvc, tvn;
825 char buf[sizeof("yyyy-mm-dd hh:mm:ss") + /*paranoia:*/ 4];
828 gettimeofday(&tvc, NULL); /* never fails */
829 dtime = tvc.tv_sec + (1.0e-6 * tvc.tv_usec) + offset;
830 d_to_tv(dtime, &tvn);
831 if (settimeofday(&tvn, NULL) == -1)
832 bb_perror_msg_and_die("settimeofday");
836 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
837 bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
840 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
841 bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
843 /* Correct various fields which contain time-relative values: */
845 /* p->lastpkt_recv_time, p->next_action_time and such: */
846 for (item = G.ntp_peers; item != NULL; item = item->link) {
847 peer_t *pp = (peer_t *) item->data;
848 reset_peer_stats(pp, offset);
849 //bb_error_msg("offset:%+f pp->next_action_time:%f -> %f",
850 // offset, pp->next_action_time, pp->next_action_time + offset);
851 pp->next_action_time += offset;
854 G.cur_time += offset;
855 G.last_update_recv_time += offset;
856 G.last_script_run += offset;
861 * Selection and clustering, and their helpers
867 double opt_rd; /* optimization */
870 compare_point_edge(const void *aa, const void *bb)
872 const point_t *a = aa;
873 const point_t *b = bb;
874 if (a->edge < b->edge) {
877 return (a->edge > b->edge);
884 compare_survivor_metric(const void *aa, const void *bb)
886 const survivor_t *a = aa;
887 const survivor_t *b = bb;
888 if (a->metric < b->metric) {
891 return (a->metric > b->metric);
894 fit(peer_t *p, double rd)
896 if ((p->reachable_bits & (p->reachable_bits-1)) == 0) {
897 /* One or zero bits in reachable_bits */
898 VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
901 #if 0 /* we filter out such packets earlier */
902 if ((p->lastpkt_status & LI_ALARM) == LI_ALARM
903 || p->lastpkt_stratum >= MAXSTRAT
905 VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
909 /* rd is root_distance(p) */
910 if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
911 VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
915 // /* Do we have a loop? */
916 // if (p->refid == p->dstaddr || p->refid == s.refid)
921 select_and_cluster(void)
926 int size = 3 * G.peer_cnt;
927 /* for selection algorithm */
929 unsigned num_points, num_candidates;
931 unsigned num_falsetickers;
932 /* for cluster algorithm */
933 survivor_t survivor[size];
934 unsigned num_survivors;
940 if (G.initial_poll_complete) while (item != NULL) {
943 p = (peer_t *) item->data;
944 rd = root_distance(p);
945 offset = p->filter_offset;
951 VERB4 bb_error_msg("interval: [%f %f %f] %s",
957 point[num_points].p = p;
958 point[num_points].type = -1;
959 point[num_points].edge = offset - rd;
960 point[num_points].opt_rd = rd;
962 point[num_points].p = p;
963 point[num_points].type = 0;
964 point[num_points].edge = offset;
965 point[num_points].opt_rd = rd;
967 point[num_points].p = p;
968 point[num_points].type = 1;
969 point[num_points].edge = offset + rd;
970 point[num_points].opt_rd = rd;
974 num_candidates = num_points / 3;
975 if (num_candidates == 0) {
976 VERB3 bb_error_msg("no valid datapoints, no peer selected");
979 //TODO: sorting does not seem to be done in reference code
980 qsort(point, num_points, sizeof(point[0]), compare_point_edge);
982 /* Start with the assumption that there are no falsetickers.
983 * Attempt to find a nonempty intersection interval containing
984 * the midpoints of all truechimers.
985 * If a nonempty interval cannot be found, increase the number
986 * of assumed falsetickers by one and try again.
987 * If a nonempty interval is found and the number of falsetickers
988 * is less than the number of truechimers, a majority has been found
989 * and the midpoint of each truechimer represents
990 * the candidates available to the cluster algorithm.
992 num_falsetickers = 0;
995 unsigned num_midpoints = 0;
1000 for (i = 0; i < num_points; i++) {
1002 * if (point[i].type == -1) c++;
1003 * if (point[i].type == 1) c--;
1004 * and it's simpler to do it this way:
1007 if (c >= num_candidates - num_falsetickers) {
1008 /* If it was c++ and it got big enough... */
1009 low = point[i].edge;
1012 if (point[i].type == 0)
1016 for (i = num_points-1; i >= 0; i--) {
1018 if (c >= num_candidates - num_falsetickers) {
1019 high = point[i].edge;
1022 if (point[i].type == 0)
1025 /* If the number of midpoints is greater than the number
1026 * of allowed falsetickers, the intersection contains at
1027 * least one truechimer with no midpoint - bad.
1028 * Also, interval should be nonempty.
1030 if (num_midpoints <= num_falsetickers && low < high)
1033 if (num_falsetickers * 2 >= num_candidates) {
1034 VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected",
1035 num_falsetickers, num_candidates);
1039 VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
1040 low, high, num_candidates, num_falsetickers);
1044 /* Construct a list of survivors (p, metric)
1045 * from the chime list, where metric is dominated
1046 * first by stratum and then by root distance.
1047 * All other things being equal, this is the order of preference.
1050 for (i = 0; i < num_points; i++) {
1051 if (point[i].edge < low || point[i].edge > high)
1054 survivor[num_survivors].p = p;
1055 /* x.opt_rd == root_distance(p); */
1056 survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + point[i].opt_rd;
1057 VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s",
1058 num_survivors, survivor[num_survivors].metric, p->p_dotted);
1061 /* There must be at least MIN_SELECTED survivors to satisfy the
1062 * correctness assertions. Ordinarily, the Byzantine criteria
1063 * require four survivors, but for the demonstration here, one
1066 if (num_survivors < MIN_SELECTED) {
1067 VERB3 bb_error_msg("num_survivors %d < %d, no peer selected",
1068 num_survivors, MIN_SELECTED);
1072 //looks like this is ONLY used by the fact that later we pick survivor[0].
1073 //we can avoid sorting then, just find the minimum once!
1074 qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric);
1076 /* For each association p in turn, calculate the selection
1077 * jitter p->sjitter as the square root of the sum of squares
1078 * (p->offset - q->offset) over all q associations. The idea is
1079 * to repeatedly discard the survivor with maximum selection
1080 * jitter until a termination condition is met.
1083 unsigned max_idx = max_idx;
1084 double max_selection_jitter = max_selection_jitter;
1085 double min_jitter = min_jitter;
1087 if (num_survivors <= MIN_CLUSTERED) {
1088 VERB3 bb_error_msg("num_survivors %d <= %d, not discarding more",
1089 num_survivors, MIN_CLUSTERED);
1093 /* To make sure a few survivors are left
1094 * for the clustering algorithm to chew on,
1095 * we stop if the number of survivors
1096 * is less than or equal to MIN_CLUSTERED (3).
1098 for (i = 0; i < num_survivors; i++) {
1099 double selection_jitter_sq;
1102 if (i == 0 || p->filter_jitter < min_jitter)
1103 min_jitter = p->filter_jitter;
1105 selection_jitter_sq = 0;
1106 for (j = 0; j < num_survivors; j++) {
1107 peer_t *q = survivor[j].p;
1108 selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
1110 if (i == 0 || selection_jitter_sq > max_selection_jitter) {
1111 max_selection_jitter = selection_jitter_sq;
1114 VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
1115 i, selection_jitter_sq);
1117 max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
1118 VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
1119 max_idx, max_selection_jitter, min_jitter);
1121 /* If the maximum selection jitter is less than the
1122 * minimum peer jitter, then tossing out more survivors
1123 * will not lower the minimum peer jitter, so we might
1126 if (max_selection_jitter < min_jitter) {
1127 VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
1128 max_selection_jitter, min_jitter, num_survivors);
1132 /* Delete survivor[max_idx] from the list
1133 * and go around again.
1135 VERB5 bb_error_msg("dropping survivor %d", max_idx);
1137 while (max_idx < num_survivors) {
1138 survivor[max_idx] = survivor[max_idx + 1];
1144 /* Combine the offsets of the clustering algorithm survivors
1145 * using a weighted average with weight determined by the root
1146 * distance. Compute the selection jitter as the weighted RMS
1147 * difference between the first survivor and the remaining
1148 * survivors. In some cases the inherent clock jitter can be
1149 * reduced by not using this algorithm, especially when frequent
1150 * clockhopping is involved. bbox: thus we don't do it.
1154 for (i = 0; i < num_survivors; i++) {
1156 x = root_distance(p);
1158 z += p->filter_offset / x;
1159 w += SQUARE(p->filter_offset - survivor[0].p->filter_offset) / x;
1161 //G.cluster_offset = z / y;
1162 //G.cluster_jitter = SQRT(w / y);
1165 /* Pick the best clock. If the old system peer is on the list
1166 * and at the same stratum as the first survivor on the list,
1167 * then don't do a clock hop. Otherwise, select the first
1168 * survivor on the list as the new system peer.
1171 if (G.last_update_peer
1172 && G.last_update_peer->lastpkt_stratum <= p->lastpkt_stratum
1174 /* Starting from 1 is ok here */
1175 for (i = 1; i < num_survivors; i++) {
1176 if (G.last_update_peer == survivor[i].p) {
1177 VERB4 bb_error_msg("keeping old synced peer");
1178 p = G.last_update_peer;
1183 G.last_update_peer = p;
1185 VERB3 bb_error_msg("selected peer %s filter_offset:%+f age:%f",
1188 G.cur_time - p->lastpkt_recv_time
1195 * Local clock discipline and its helpers
1198 set_new_values(int disc_state, double offset, double recv_time)
1200 /* Enter new state and set state variables. Note we use the time
1201 * of the last clock filter sample, which must be earlier than
1204 VERB3 bb_error_msg("disc_state=%d last update offset=%f recv_time=%f",
1205 disc_state, offset, recv_time);
1206 G.discipline_state = disc_state;
1207 G.last_update_offset = offset;
1208 G.last_update_recv_time = recv_time;
1210 /* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
1212 update_local_clock(peer_t *p)
1216 /* Note: can use G.cluster_offset instead: */
1217 double offset = p->filter_offset;
1218 double recv_time = p->lastpkt_recv_time;
1220 #if !USING_KERNEL_PLL_LOOP
1223 double since_last_update;
1224 double etemp, dtemp;
1226 abs_offset = fabs(offset);
1229 /* If needed, -S script can do it by looking at $offset
1230 * env var and killing parent */
1231 /* If the offset is too large, give up and go home */
1232 if (abs_offset > PANIC_THRESHOLD) {
1233 bb_error_msg_and_die("offset %f far too big, exiting", offset);
1237 /* If this is an old update, for instance as the result
1238 * of a system peer change, avoid it. We never use
1239 * an old sample or the same sample twice.
1241 if (recv_time <= G.last_update_recv_time) {
1242 VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it",
1243 G.last_update_recv_time, recv_time);
1244 return 0; /* "leave poll interval as is" */
1247 /* Clock state machine transition function. This is where the
1248 * action is and defines how the system reacts to large time
1249 * and frequency errors.
1251 since_last_update = recv_time - G.reftime;
1252 #if !USING_KERNEL_PLL_LOOP
1255 #if USING_INITIAL_FREQ_ESTIMATION
1256 if (G.discipline_state == STATE_FREQ) {
1257 /* Ignore updates until the stepout threshold */
1258 if (since_last_update < WATCH_THRESHOLD) {
1259 VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
1260 WATCH_THRESHOLD - since_last_update);
1261 return 0; /* "leave poll interval as is" */
1263 # if !USING_KERNEL_PLL_LOOP
1264 freq_drift = (offset - G.last_update_offset) / since_last_update;
1269 /* There are two main regimes: when the
1270 * offset exceeds the step threshold and when it does not.
1272 if (abs_offset > STEP_THRESHOLD) {
1273 switch (G.discipline_state) {
1275 /* The first outlyer: ignore it, switch to SPIK state */
1276 VERB3 bb_error_msg("offset:%+f - spike detected", offset);
1277 G.discipline_state = STATE_SPIK;
1278 return -1; /* "decrease poll interval" */
1281 /* Ignore succeeding outlyers until either an inlyer
1282 * is found or the stepout threshold is exceeded.
1284 if (since_last_update < WATCH_THRESHOLD) {
1285 VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains",
1286 WATCH_THRESHOLD - since_last_update);
1287 return -1; /* "decrease poll interval" */
1289 /* fall through: we need to step */
1292 /* Step the time and clamp down the poll interval.
1294 * In NSET state an initial frequency correction is
1295 * not available, usually because the frequency file has
1296 * not yet been written. Since the time is outside the
1297 * capture range, the clock is stepped. The frequency
1298 * will be set directly following the stepout interval.
1300 * In FSET state the initial frequency has been set
1301 * from the frequency file. Since the time is outside
1302 * the capture range, the clock is stepped immediately,
1303 * rather than after the stepout interval. Guys get
1304 * nervous if it takes 17 minutes to set the clock for
1307 * In SPIK state the stepout threshold has expired and
1308 * the phase is still above the step threshold. Note
1309 * that a single spike greater than the step threshold
1310 * is always suppressed, even at the longer poll
1313 VERB3 bb_error_msg("stepping time by %+f; poll_exp=MINPOLL", offset);
1315 if (option_mask32 & OPT_q) {
1316 /* We were only asked to set time once. Done. */
1320 G.polladj_count = 0;
1321 G.poll_exp = MINPOLL;
1322 G.stratum = MAXSTRAT;
1324 run_script("step", offset);
1326 #if USING_INITIAL_FREQ_ESTIMATION
1327 if (G.discipline_state == STATE_NSET) {
1328 set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
1329 return 1; /* "ok to increase poll interval" */
1332 set_new_values(STATE_SYNC, /*offset:*/ 0, recv_time);
1334 } else { /* abs_offset <= STEP_THRESHOLD */
1336 if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
1337 VERB3 bb_error_msg("small offset:%+f, disabling burst mode", offset);
1338 G.polladj_count = 0;
1339 G.poll_exp = MINPOLL;
1342 /* Compute the clock jitter as the RMS of exponentially
1343 * weighted offset differences. Used by the poll adjust code.
1345 etemp = SQUARE(G.discipline_jitter);
1346 dtemp = SQUARE(offset - G.last_update_offset);
1347 G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
1348 if (G.discipline_jitter < G_precision_sec)
1349 G.discipline_jitter = G_precision_sec;
1350 VERB3 bb_error_msg("discipline jitter=%f", G.discipline_jitter);
1352 switch (G.discipline_state) {
1354 if (option_mask32 & OPT_q) {
1355 /* We were only asked to set time once.
1356 * The clock is precise enough, no need to step.
1360 #if USING_INITIAL_FREQ_ESTIMATION
1361 /* This is the first update received and the frequency
1362 * has not been initialized. The first thing to do
1363 * is directly measure the oscillator frequency.
1365 set_new_values(STATE_FREQ, offset, recv_time);
1367 set_new_values(STATE_SYNC, offset, recv_time);
1369 VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
1370 return 0; /* "leave poll interval as is" */
1372 #if 0 /* this is dead code for now */
1374 /* This is the first update and the frequency
1375 * has been initialized. Adjust the phase, but
1376 * don't adjust the frequency until the next update.
1378 set_new_values(STATE_SYNC, offset, recv_time);
1379 /* freq_drift remains 0 */
1383 #if USING_INITIAL_FREQ_ESTIMATION
1385 /* since_last_update >= WATCH_THRESHOLD, we waited enough.
1386 * Correct the phase and frequency and switch to SYNC state.
1387 * freq_drift was already estimated (see code above)
1389 set_new_values(STATE_SYNC, offset, recv_time);
1394 #if !USING_KERNEL_PLL_LOOP
1395 /* Compute freq_drift due to PLL and FLL contributions.
1397 * The FLL and PLL frequency gain constants
1398 * depend on the poll interval and Allan
1399 * intercept. The FLL is not used below one-half
1400 * the Allan intercept. Above that the loop gain
1401 * increases in steps to 1 / AVG.
1403 if ((1 << G.poll_exp) > ALLAN / 2) {
1404 etemp = FLL - G.poll_exp;
1407 freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp);
1409 /* For the PLL the integration interval
1410 * (numerator) is the minimum of the update
1411 * interval and poll interval. This allows
1412 * oversampling, but not undersampling.
1414 etemp = MIND(since_last_update, (1 << G.poll_exp));
1415 dtemp = (4 * PLL) << G.poll_exp;
1416 freq_drift += offset * etemp / SQUARE(dtemp);
1418 set_new_values(STATE_SYNC, offset, recv_time);
1421 if (G.stratum != p->lastpkt_stratum + 1) {
1422 G.stratum = p->lastpkt_stratum + 1;
1423 run_script("stratum", offset);
1427 G.reftime = G.cur_time;
1428 G.ntp_status = p->lastpkt_status;
1429 G.refid = p->lastpkt_refid;
1430 G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
1431 dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(G.cluster_jitter));
1432 dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time) + abs_offset, MINDISP);
1433 G.rootdisp = p->lastpkt_rootdisp + dtemp;
1434 VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted);
1436 /* We are in STATE_SYNC now, but did not do adjtimex yet.
1437 * (Any other state does not reach this, they all return earlier)
1438 * By this time, freq_drift and G.last_update_offset are set
1439 * to values suitable for adjtimex.
1441 #if !USING_KERNEL_PLL_LOOP
1442 /* Calculate the new frequency drift and frequency stability (wander).
1443 * Compute the clock wander as the RMS of exponentially weighted
1444 * frequency differences. This is not used directly, but can,
1445 * along with the jitter, be a highly useful monitoring and
1448 dtemp = G.discipline_freq_drift + freq_drift;
1449 G.discipline_freq_drift = MAXD(MIND(MAXDRIFT, dtemp), -MAXDRIFT);
1450 etemp = SQUARE(G.discipline_wander);
1451 dtemp = SQUARE(dtemp);
1452 G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
1454 VERB3 bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
1455 G.discipline_freq_drift,
1456 (long)(G.discipline_freq_drift * 65536e6),
1458 G.discipline_wander);
1461 memset(&tmx, 0, sizeof(tmx));
1462 if (adjtimex(&tmx) < 0)
1463 bb_perror_msg_and_die("adjtimex");
1464 VERB3 bb_error_msg("p adjtimex freq:%ld offset:%+ld constant:%ld status:0x%x",
1465 tmx.freq, tmx.offset, tmx.constant, tmx.status);
1468 memset(&tmx, 0, sizeof(tmx));
1470 //doesn't work, offset remains 0 (!) in kernel:
1471 //ntpd: set adjtimex freq:1786097 tmx.offset:77487
1472 //ntpd: prev adjtimex freq:1786097 tmx.offset:0
1473 //ntpd: cur adjtimex freq:1786097 tmx.offset:0
1474 tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET;
1475 /* 65536 is one ppm */
1476 tmx.freq = G.discipline_freq_drift * 65536e6;
1477 tmx.offset = G.last_update_offset * 1000000; /* usec */
1479 tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
1480 tmx.offset = (G.last_update_offset * 1000000); /* usec */
1481 /* + (G.last_update_offset < 0 ? -0.5 : 0.5) - too small to bother */
1482 tmx.status = STA_PLL;
1483 if (G.ntp_status & LI_PLUSSEC)
1484 tmx.status |= STA_INS;
1485 if (G.ntp_status & LI_MINUSSEC)
1486 tmx.status |= STA_DEL;
1487 tmx.constant = G.poll_exp - 4;
1488 //tmx.esterror = (u_int32)(clock_jitter * 1e6);
1489 //tmx.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
1490 rc = adjtimex(&tmx);
1492 bb_perror_msg_and_die("adjtimex");
1493 /* NB: here kernel returns constant == G.poll_exp, not == G.poll_exp - 4.
1494 * Not sure why. Perhaps it is normal.
1496 VERB3 bb_error_msg("adjtimex:%d freq:%ld offset:%+ld constant:%ld status:0x%x",
1497 rc, tmx.freq, tmx.offset, tmx.constant, tmx.status);
1500 /* always gives the same output as above msg */
1501 memset(&tmx, 0, sizeof(tmx));
1502 if (adjtimex(&tmx) < 0)
1503 bb_perror_msg_and_die("adjtimex");
1504 VERB3 bb_error_msg("c adjtimex freq:%ld offset:%+ld constant:%ld status:0x%x",
1505 tmx.freq, tmx.offset, tmx.constant, tmx.status);
1508 G.kernel_freq_drift = tmx.freq / 65536;
1509 VERB2 bb_error_msg("update peer:%s, offset:%+f, jitter:%f, clock drift:%+ld ppm",
1510 p->p_dotted, G.last_update_offset, G.discipline_jitter, G.kernel_freq_drift);
1512 return 1; /* "ok to increase poll interval" */
1517 * We've got a new reply packet from a peer, process it
1521 retry_interval(void)
1523 /* Local problem, want to retry soon */
1524 unsigned interval, r;
1525 interval = RETRY_INTERVAL;
1527 interval += r % (unsigned)(RETRY_INTERVAL / 4);
1528 VERB3 bb_error_msg("chose retry interval:%u", interval);
1532 poll_interval(int exponent)
1534 unsigned interval, r;
1535 exponent = G.poll_exp + exponent;
1538 interval = 1 << exponent;
1540 interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
1541 VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
1544 static NOINLINE void
1545 recv_and_process_peer_pkt(peer_t *p)
1550 double T1, T2, T3, T4;
1552 datapoint_t *datapoint;
1555 /* We can recvfrom here and check from.IP, but some multihomed
1556 * ntp servers reply from their *other IP*.
1557 * TODO: maybe we should check at least what we can: from.port == 123?
1559 size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
1561 bb_perror_msg("recv(%s) error", p->p_dotted);
1562 if (errno == EHOSTUNREACH || errno == EHOSTDOWN
1563 || errno == ENETUNREACH || errno == ENETDOWN
1564 || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
1567 //TODO: always do this?
1568 interval = retry_interval();
1569 goto set_next_and_close_sock;
1574 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1575 bb_error_msg("malformed packet received from %s", p->p_dotted);
1579 if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
1580 || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
1585 if ((msg.m_status & LI_ALARM) == LI_ALARM
1586 || msg.m_stratum == 0
1587 || msg.m_stratum > NTP_MAXSTRATUM
1589 // TODO: stratum 0 responses may have commands in 32-bit m_refid field:
1590 // "DENY", "RSTR" - peer does not like us at all
1591 // "RATE" - peer is overloaded, reduce polling freq
1592 interval = poll_interval(0);
1593 bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
1594 goto set_next_and_close_sock;
1597 // /* Verify valid root distance */
1598 // if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
1599 // return; /* invalid header values */
1601 p->lastpkt_status = msg.m_status;
1602 p->lastpkt_stratum = msg.m_stratum;
1603 p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
1604 p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
1605 p->lastpkt_refid = msg.m_refid;
1608 * From RFC 2030 (with a correction to the delay math):
1610 * Timestamp Name ID When Generated
1611 * ------------------------------------------------------------
1612 * Originate Timestamp T1 time request sent by client
1613 * Receive Timestamp T2 time request received by server
1614 * Transmit Timestamp T3 time reply sent by server
1615 * Destination Timestamp T4 time reply received by client
1617 * The roundtrip delay and local clock offset are defined as
1619 * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
1622 T2 = lfp_to_d(msg.m_rectime);
1623 T3 = lfp_to_d(msg.m_xmttime);
1626 p->lastpkt_recv_time = T4;
1628 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
1629 p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
1630 datapoint = &p->filter_datapoint[p->datapoint_idx];
1631 datapoint->d_recv_time = T4;
1632 datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
1633 /* The delay calculation is a special case. In cases where the
1634 * server and client clocks are running at different rates and
1635 * with very fast networks, the delay can appear negative. In
1636 * order to avoid violating the Principle of Least Astonishment,
1637 * the delay is clamped not less than the system precision.
1639 p->lastpkt_delay = (T4 - T1) - (T3 - T2);
1640 if (p->lastpkt_delay < G_precision_sec)
1641 p->lastpkt_delay = G_precision_sec;
1642 datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
1643 if (!p->reachable_bits) {
1644 /* 1st datapoint ever - replicate offset in every element */
1646 for (i = 1; i < NUM_DATAPOINTS; i++) {
1647 p->filter_datapoint[i].d_offset = datapoint->d_offset;
1651 p->reachable_bits |= 1;
1652 if ((MAX_VERBOSE && G.verbose) || (option_mask32 & OPT_w)) {
1653 bb_error_msg("reply from %s: reach 0x%02x offset %+f delay %f status 0x%02x strat %d refid 0x%08x rootdelay %f",
1656 datapoint->d_offset,
1661 p->lastpkt_rootdelay
1662 /* not shown: m_ppoll, m_precision_exp, m_rootdisp,
1663 * m_reftime, m_orgtime, m_rectime, m_xmttime
1668 /* Muck with statictics and update the clock */
1669 filter_datapoints(p);
1670 q = select_and_cluster();
1674 if (!(option_mask32 & OPT_w)) {
1675 rc = update_local_clock(q);
1676 /* If drift is dangerously large, immediately
1677 * drop poll interval one step down.
1679 if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) {
1680 VERB3 bb_error_msg("offset:%+f > POLLDOWN_OFFSET", q->filter_offset);
1685 /* else: no peer selected, rc = -1: we want to poll more often */
1688 /* Adjust the poll interval by comparing the current offset
1689 * with the clock jitter. If the offset is less than
1690 * the clock jitter times a constant, then the averaging interval
1691 * is increased, otherwise it is decreased. A bit of hysteresis
1692 * helps calm the dance. Works best using burst mode.
1695 bb_error_msg("offset:%+f POLLADJ_GATE*discipline_jitter:%f poll:%s",
1696 q->filter_offset, POLLADJ_GATE * G.discipline_jitter,
1697 fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter
1701 if (rc > 0 && fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter) {
1702 /* was += G.poll_exp but it is a bit
1703 * too optimistic for my taste at high poll_exp's */
1704 G.polladj_count += MINPOLL;
1705 if (G.polladj_count > POLLADJ_LIMIT) {
1706 G.polladj_count = 0;
1707 if (G.poll_exp < MAXPOLL) {
1709 VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
1710 G.discipline_jitter, G.poll_exp);
1713 VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count);
1716 G.polladj_count -= G.poll_exp * 2;
1717 if (G.polladj_count < -POLLADJ_LIMIT || G.poll_exp >= BIGPOLL) {
1719 G.polladj_count = 0;
1720 if (G.poll_exp > MINPOLL) {
1724 /* Correct p->next_action_time in each peer
1725 * which waits for sending, so that they send earlier.
1726 * Old pp->next_action_time are on the order
1727 * of t + (1 << old_poll_exp) + small_random,
1728 * we simply need to subtract ~half of that.
1730 for (item = G.ntp_peers; item != NULL; item = item->link) {
1731 peer_t *pp = (peer_t *) item->data;
1733 pp->next_action_time -= (1 << G.poll_exp);
1735 VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
1736 G.discipline_jitter, G.poll_exp);
1739 VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count);
1744 /* Decide when to send new query for this peer */
1745 interval = poll_interval(0);
1747 set_next_and_close_sock:
1748 set_next(p, interval);
1749 /* We do not expect any more packets from this peer for now.
1750 * Closing the socket informs kernel about it.
1751 * We open a new socket when we send a new query.
1759 #if ENABLE_FEATURE_NTPD_SERVER
1760 static NOINLINE void
1761 recv_and_process_client_pkt(void /*int fd*/)
1765 len_and_sockaddr *to;
1766 struct sockaddr *from;
1768 uint8_t query_status;
1769 l_fixedpt_t query_xmttime;
1771 to = get_sock_lsa(G.listen_fd);
1772 from = xzalloc(to->len);
1774 size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
1775 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1778 if (errno == EAGAIN)
1780 bb_perror_msg_and_die("recv");
1782 addr = xmalloc_sockaddr2dotted_noport(from);
1783 bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
1788 query_status = msg.m_status;
1789 query_xmttime = msg.m_xmttime;
1791 /* Build a reply packet */
1792 memset(&msg, 0, sizeof(msg));
1793 msg.m_status = G.stratum < MAXSTRAT ? G.ntp_status : LI_ALARM;
1794 msg.m_status |= (query_status & VERSION_MASK);
1795 msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
1796 MODE_SERVER : MODE_SYM_PAS;
1797 msg.m_stratum = G.stratum;
1798 msg.m_ppoll = G.poll_exp;
1799 msg.m_precision_exp = G_precision_exp;
1800 /* this time was obtained between poll() and recv() */
1801 msg.m_rectime = d_to_lfp(G.cur_time);
1802 msg.m_xmttime = d_to_lfp(gettime1900d()); /* this instant */
1803 if (G.peer_cnt == 0) {
1804 /* we have no peers: "stratum 1 server" mode. reftime = our own time */
1805 G.reftime = G.cur_time;
1807 msg.m_reftime = d_to_lfp(G.reftime);
1808 msg.m_orgtime = query_xmttime;
1809 msg.m_rootdelay = d_to_sfp(G.rootdelay);
1810 //simple code does not do this, fix simple code!
1811 msg.m_rootdisp = d_to_sfp(G.rootdisp);
1812 //version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
1813 msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3;
1815 /* We reply from the local address packet was sent to,
1816 * this makes to/from look swapped here: */
1817 do_sendto(G.listen_fd,
1818 /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
1827 /* Upstream ntpd's options:
1829 * -4 Force DNS resolution of host names to the IPv4 namespace.
1830 * -6 Force DNS resolution of host names to the IPv6 namespace.
1831 * -a Require cryptographic authentication for broadcast client,
1832 * multicast client and symmetric passive associations.
1833 * This is the default.
1834 * -A Do not require cryptographic authentication for broadcast client,
1835 * multicast client and symmetric passive associations.
1836 * This is almost never a good idea.
1837 * -b Enable the client to synchronize to broadcast servers.
1839 * Specify the name and path of the configuration file,
1840 * default /etc/ntp.conf
1841 * -d Specify debugging mode. This option may occur more than once,
1842 * with each occurrence indicating greater detail of display.
1844 * Specify debugging level directly.
1846 * Specify the name and path of the frequency file.
1847 * This is the same operation as the "driftfile FILE"
1848 * configuration command.
1849 * -g Normally, ntpd exits with a message to the system log
1850 * if the offset exceeds the panic threshold, which is 1000 s
1851 * by default. This option allows the time to be set to any value
1852 * without restriction; however, this can happen only once.
1853 * If the threshold is exceeded after that, ntpd will exit
1854 * with a message to the system log. This option can be used
1855 * with the -q and -x options. See the tinker command for other options.
1857 * Chroot the server to the directory jaildir. This option also implies
1858 * that the server attempts to drop root privileges at startup
1859 * (otherwise, chroot gives very little additional security).
1860 * You may need to also specify a -u option.
1862 * Specify the name and path of the symmetric key file,
1863 * default /etc/ntp/keys. This is the same operation
1864 * as the "keys FILE" configuration command.
1866 * Specify the name and path of the log file. The default
1867 * is the system log file. This is the same operation as
1868 * the "logfile FILE" configuration command.
1869 * -L Do not listen to virtual IPs. The default is to listen.
1871 * -N To the extent permitted by the operating system,
1872 * run the ntpd at the highest priority.
1874 * Specify the name and path of the file used to record the ntpd
1875 * process ID. This is the same operation as the "pidfile FILE"
1876 * configuration command.
1878 * To the extent permitted by the operating system,
1879 * run the ntpd at the specified priority.
1880 * -q Exit the ntpd just after the first time the clock is set.
1881 * This behavior mimics that of the ntpdate program, which is
1882 * to be retired. The -g and -x options can be used with this option.
1883 * Note: The kernel time discipline is disabled with this option.
1885 * Specify the default propagation delay from the broadcast/multicast
1886 * server to this client. This is necessary only if the delay
1887 * cannot be computed automatically by the protocol.
1889 * Specify the directory path for files created by the statistics
1890 * facility. This is the same operation as the "statsdir DIR"
1891 * configuration command.
1893 * Add a key number to the trusted key list. This option can occur
1896 * Specify a user, and optionally a group, to switch to.
1899 * Add a system variable listed by default.
1900 * -x Normally, the time is slewed if the offset is less than the step
1901 * threshold, which is 128 ms by default, and stepped if above
1902 * the threshold. This option sets the threshold to 600 s, which is
1903 * well within the accuracy window to set the clock manually.
1904 * Note: since the slew rate of typical Unix kernels is limited
1905 * to 0.5 ms/s, each second of adjustment requires an amortization
1906 * interval of 2000 s. Thus, an adjustment as much as 600 s
1907 * will take almost 14 days to complete. This option can be used
1908 * with the -g and -q options. See the tinker command for other options.
1909 * Note: The kernel time discipline is disabled with this option.
1912 /* By doing init in a separate function we decrease stack usage
1915 static NOINLINE void ntp_init(char **argv)
1923 bb_error_msg_and_die(bb_msg_you_must_be_root);
1925 /* Set some globals */
1926 G.stratum = MAXSTRAT;
1928 G.poll_exp = BURSTPOLL; /* speeds up initial sync */
1929 G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
1933 opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
1934 opts = getopt32(argv,
1936 "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
1938 "46aAbgL", /* compat, ignored */
1939 &peers, &G.script_name, &G.verbose);
1940 if (!(opts & (OPT_p|OPT_l)))
1942 // if (opts & OPT_x) /* disable stepping, only slew is allowed */
1943 // G.time_was_stepped = 1;
1946 add_peers(llist_pop(&peers));
1948 /* -l but no peers: "stratum 1 server" mode */
1951 if (!(opts & OPT_n)) {
1952 bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
1953 logmode = LOGMODE_NONE;
1955 #if ENABLE_FEATURE_NTPD_SERVER
1958 G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
1959 socket_want_pktinfo(G.listen_fd);
1960 setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
1963 /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
1965 setpriority(PRIO_PROCESS, 0, -15);
1967 /* If network is up, syncronization occurs in ~10 seconds.
1968 * We give "ntpd -q" 10 seconds to get first reply,
1969 * then another 50 seconds to finish syncing.
1971 * I tested ntpd 4.2.6p1 and apparently it never exits
1972 * (will try forever), but it does not feel right.
1973 * The goal of -q is to act like ntpdate: set time
1974 * after a reasonably small period of polling, or fail.
1977 option_mask32 |= OPT_qq;
1994 int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
1995 int ntpd_main(int argc UNUSED_PARAM, char **argv)
2003 memset(&G, 0, sizeof(G));
2004 SET_PTR_TO_GLOBALS(&G);
2008 /* If ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
2009 cnt = G.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
2010 idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
2011 pfd = xzalloc(sizeof(pfd[0]) * cnt);
2013 /* Countdown: we never sync before we sent INITIAL_SAMPLES+1
2014 * packets to each peer.
2015 * NB: if some peer is not responding, we may end up sending
2016 * fewer packets to it and more to other peers.
2017 * NB2: sync usually happens using INITIAL_SAMPLES packets,
2018 * since last reply does not come back instantaneously.
2020 cnt = G.peer_cnt * (INITIAL_SAMPLES + 1);
2022 while (!bb_got_signal) {
2028 /* Nothing between here and poll() blocks for any significant time */
2030 nextaction = G.cur_time + 3600;
2033 #if ENABLE_FEATURE_NTPD_SERVER
2034 if (G.listen_fd != -1) {
2035 pfd[0].fd = G.listen_fd;
2036 pfd[0].events = POLLIN;
2040 /* Pass over peer list, send requests, time out on receives */
2041 for (item = G.ntp_peers; item != NULL; item = item->link) {
2042 peer_t *p = (peer_t *) item->data;
2044 if (p->next_action_time <= G.cur_time) {
2045 if (p->p_fd == -1) {
2046 /* Time to send new req */
2048 G.initial_poll_complete = 1;
2050 send_query_to_peer(p);
2052 /* Timed out waiting for reply */
2055 timeout = poll_interval(-2); /* -2: try a bit sooner */
2056 bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
2057 p->p_dotted, p->reachable_bits, timeout);
2058 set_next(p, timeout);
2062 if (p->next_action_time < nextaction)
2063 nextaction = p->next_action_time;
2066 /* Wait for reply from this peer */
2067 pfd[i].fd = p->p_fd;
2068 pfd[i].events = POLLIN;
2074 timeout = nextaction - G.cur_time;
2077 timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
2079 /* Here we may block */
2080 VERB2 bb_error_msg("poll %us, sockets:%u, poll interval:%us", timeout, i, 1 << G.poll_exp);
2081 nfds = poll(pfd, i, timeout * 1000);
2082 gettime1900d(); /* sets G.cur_time */
2084 if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
2085 /* Useful for updating battery-backed RTC and such */
2086 run_script("periodic", G.last_update_offset);
2087 gettime1900d(); /* sets G.cur_time */
2092 /* Process any received packets */
2094 #if ENABLE_FEATURE_NTPD_SERVER
2095 if (G.listen_fd != -1) {
2096 if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
2098 recv_and_process_client_pkt(/*G.listen_fd*/);
2099 gettime1900d(); /* sets G.cur_time */
2104 for (; nfds != 0 && j < i; j++) {
2105 if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
2107 * At init, alarm was set to 10 sec.
2108 * Now we did get a reply.
2109 * Increase timeout to 50 seconds to finish syncing.
2111 if (option_mask32 & OPT_qq) {
2112 option_mask32 &= ~OPT_qq;
2116 recv_and_process_peer_pkt(idx2peer[j]);
2117 gettime1900d(); /* sets G.cur_time */
2120 } /* while (!bb_got_signal) */
2122 kill_myself_with_sig(bb_got_signal);
2130 /*** openntpd-4.6 uses only adjtime, not adjtimex ***/
2132 /*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/
2136 direct_freq(double fp_offset)
2140 * If the kernel is enabled, we need the residual offset to
2141 * calculate the frequency correction.
2143 if (pll_control && kern_enable) {
2144 memset(&ntv, 0, sizeof(ntv));
2147 clock_offset = ntv.offset / 1e9;
2148 #else /* STA_NANO */
2149 clock_offset = ntv.offset / 1e6;
2150 #endif /* STA_NANO */
2151 drift_comp = FREQTOD(ntv.freq);
2153 #endif /* KERNEL_PLL */
2154 set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp);
2160 set_freq(double freq) /* frequency update */
2168 * If the kernel is enabled, update the kernel frequency.
2170 if (pll_control && kern_enable) {
2171 memset(&ntv, 0, sizeof(ntv));
2172 ntv.modes = MOD_FREQUENCY;
2173 ntv.freq = DTOFREQ(drift_comp);
2175 snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6);
2176 report_event(EVNT_FSET, NULL, tbuf);
2178 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2179 report_event(EVNT_FSET, NULL, tbuf);
2181 #else /* KERNEL_PLL */
2182 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2183 report_event(EVNT_FSET, NULL, tbuf);
2184 #endif /* KERNEL_PLL */
2193 * This code segment works when clock adjustments are made using
2194 * precision time kernel support and the ntp_adjtime() system
2195 * call. This support is available in Solaris 2.6 and later,
2196 * Digital Unix 4.0 and later, FreeBSD, Linux and specially
2197 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
2198 * DECstation 5000/240 and Alpha AXP, additional kernel
2199 * modifications provide a true microsecond clock and nanosecond
2200 * clock, respectively.
2202 * Important note: The kernel discipline is used only if the
2203 * step threshold is less than 0.5 s, as anything higher can
2204 * lead to overflow problems. This might occur if some misguided
2205 * lad set the step threshold to something ridiculous.
2207 if (pll_control && kern_enable) {
2209 #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST)
2212 * We initialize the structure for the ntp_adjtime()
2213 * system call. We have to convert everything to
2214 * microseconds or nanoseconds first. Do not update the
2215 * system variables if the ext_enable flag is set. In
2216 * this case, the external clock driver will update the
2217 * variables, which will be read later by the local
2218 * clock driver. Afterwards, remember the time and
2219 * frequency offsets for jitter and stability values and
2220 * to update the frequency file.
2222 memset(&ntv, 0, sizeof(ntv));
2224 ntv.modes = MOD_STATUS;
2227 ntv.modes = MOD_BITS | MOD_NANO;
2228 #else /* STA_NANO */
2229 ntv.modes = MOD_BITS;
2230 #endif /* STA_NANO */
2231 if (clock_offset < 0)
2236 ntv.offset = (int32)(clock_offset * 1e9 + dtemp);
2237 ntv.constant = sys_poll;
2238 #else /* STA_NANO */
2239 ntv.offset = (int32)(clock_offset * 1e6 + dtemp);
2240 ntv.constant = sys_poll - 4;
2241 #endif /* STA_NANO */
2242 ntv.esterror = (u_int32)(clock_jitter * 1e6);
2243 ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
2244 ntv.status = STA_PLL;
2247 * Enable/disable the PPS if requested.
2250 if (!(pll_status & STA_PPSTIME))
2251 report_event(EVNT_KERN,
2252 NULL, "PPS enabled");
2253 ntv.status |= STA_PPSTIME | STA_PPSFREQ;
2255 if (pll_status & STA_PPSTIME)
2256 report_event(EVNT_KERN,
2257 NULL, "PPS disabled");
2258 ntv.status &= ~(STA_PPSTIME |
2261 if (sys_leap == LEAP_ADDSECOND)
2262 ntv.status |= STA_INS;
2263 else if (sys_leap == LEAP_DELSECOND)
2264 ntv.status |= STA_DEL;
2268 * Pass the stuff to the kernel. If it squeals, turn off
2269 * the pps. In any case, fetch the kernel offset,
2270 * frequency and jitter.
2272 if (ntp_adjtime(&ntv) == TIME_ERROR) {
2273 if (!(ntv.status & STA_PPSSIGNAL))
2274 report_event(EVNT_KERN, NULL,
2277 pll_status = ntv.status;
2279 clock_offset = ntv.offset / 1e9;
2280 #else /* STA_NANO */
2281 clock_offset = ntv.offset / 1e6;
2282 #endif /* STA_NANO */
2283 clock_frequency = FREQTOD(ntv.freq);
2286 * If the kernel PPS is lit, monitor its performance.
2288 if (ntv.status & STA_PPSTIME) {
2290 clock_jitter = ntv.jitter / 1e9;
2291 #else /* STA_NANO */
2292 clock_jitter = ntv.jitter / 1e6;
2293 #endif /* STA_NANO */
2296 #if defined(STA_NANO) && NTP_API == 4
2298 * If the TAI changes, update the kernel TAI.
2300 if (loop_tai != sys_tai) {
2302 ntv.modes = MOD_TAI;
2303 ntv.constant = sys_tai;
2306 #endif /* STA_NANO */
2308 #endif /* KERNEL_PLL */