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 of MD5 hash of IPv6
287 /* precision is defined as the larger of the resolution and time to
288 * read the clock, in log2 units. For instance, the precision of a
289 * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
290 * system clock hardware representation is to the nanosecond.
292 * Delays, jitters of various kinds are clamper down to precision.
294 * If precision_sec is too large, discipline_jitter gets clamped to it
295 * and if offset is much smaller than discipline_jitter, poll interval
296 * grows even though we really can benefit from staying at smaller one,
297 * collecting non-lagged datapoits and correcting the offset.
298 * (Lagged datapoits exist when poll_exp is large but we still have
299 * systematic offset error - the time distance between datapoints
300 * is significat and older datapoints have smaller offsets.
301 * This makes our offset estimation a bit smaller than reality)
302 * Due to this effect, setting G_precision_sec close to
303 * STEP_THRESHOLD isn't such a good idea - offsets may grow
304 * too big and we will step. I observed it with -6.
306 * OTOH, setting precision too small would result in futile attempts
307 * to syncronize to the unachievable precision.
309 * -6 is 1/64 sec, -7 is 1/128 sec and so on.
311 #define G_precision_exp -8
312 #define G_precision_sec (1.0 / (1 << (- G_precision_exp)))
314 /* Bool. After set to 1, never goes back to 0: */
315 smallint initial_poll_complete;
317 #define STATE_NSET 0 /* initial state, "nothing is set" */
318 //#define STATE_FSET 1 /* frequency set from file */
319 #define STATE_SPIK 2 /* spike detected */
320 //#define STATE_FREQ 3 /* initial frequency */
321 #define STATE_SYNC 4 /* clock synchronized (normal operation) */
322 uint8_t discipline_state; // doc calls it c.state
323 uint8_t poll_exp; // s.poll
324 int polladj_count; // c.count
325 long kernel_freq_drift;
326 peer_t *last_update_peer;
327 double last_update_offset; // c.last
328 double last_update_recv_time; // s.t
329 double discipline_jitter; // c.jitter
330 //double cluster_offset; // s.offset
331 //double cluster_jitter; // s.jitter
332 #if !USING_KERNEL_PLL_LOOP
333 double discipline_freq_drift; // c.freq
334 /* Maybe conditionally calculate wander? it's used only for logging */
335 double discipline_wander; // c.wander
338 #define G (*ptr_to_globals)
340 static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
343 #define VERB1 if (MAX_VERBOSE && G.verbose)
344 #define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
345 #define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
346 #define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
347 #define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
350 static double LOG2D(int a)
353 return 1.0 / (1UL << -a);
356 static ALWAYS_INLINE double SQUARE(double x)
360 static ALWAYS_INLINE double MAXD(double a, double b)
366 static ALWAYS_INLINE double MIND(double a, double b)
372 static NOINLINE double my_SQRT(double X)
379 double Xhalf = X * 0.5;
381 /* Fast and good approximation to 1/sqrt(X), black magic */
383 /*v.i = 0x5f3759df - (v.i >> 1);*/
384 v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
385 invsqrt = v.f; /* better than 0.2% accuracy */
387 /* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
388 * f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
390 * f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
391 * x1 = x0 - (X*x0*x0*x0/2 - x0/2) = 1.5*x0 - X*x0*x0*x0/2 = x0*(1.5 - (X/2)*x0*x0)
393 invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
394 /* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
395 /* With 4 iterations, more than half results will be exact,
396 * at 6th iterations result stabilizes with about 72% results exact.
397 * We are well satisfied with 0.05% accuracy.
400 return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
402 static ALWAYS_INLINE double SQRT(double X)
404 /* If this arch doesn't use IEEE 754 floats, fall back to using libm */
405 if (sizeof(float) != 4)
408 /* This avoids needing libm, saves about 0.5k on x86-32 */
416 gettimeofday(&tv, NULL); /* never fails */
417 G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
422 d_to_tv(double d, struct timeval *tv)
424 tv->tv_sec = (long)d;
425 tv->tv_usec = (d - tv->tv_sec) * 1000000;
429 lfp_to_d(l_fixedpt_t lfp)
432 lfp.int_partl = ntohl(lfp.int_partl);
433 lfp.fractionl = ntohl(lfp.fractionl);
434 ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
438 sfp_to_d(s_fixedpt_t sfp)
441 sfp.int_parts = ntohs(sfp.int_parts);
442 sfp.fractions = ntohs(sfp.fractions);
443 ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
446 #if ENABLE_FEATURE_NTPD_SERVER
451 lfp.int_partl = (uint32_t)d;
452 lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
453 lfp.int_partl = htonl(lfp.int_partl);
454 lfp.fractionl = htonl(lfp.fractionl);
461 sfp.int_parts = (uint16_t)d;
462 sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
463 sfp.int_parts = htons(sfp.int_parts);
464 sfp.fractions = htons(sfp.fractions);
470 dispersion(const datapoint_t *dp)
472 return dp->d_dispersion + FREQ_TOLERANCE * (G.cur_time - dp->d_recv_time);
476 root_distance(peer_t *p)
478 /* The root synchronization distance is the maximum error due to
479 * all causes of the local clock relative to the primary server.
480 * It is defined as half the total delay plus total dispersion
483 return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2
484 + p->lastpkt_rootdisp
485 + p->filter_dispersion
486 + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time)
491 set_next(peer_t *p, unsigned t)
493 p->next_action_time = G.cur_time + t;
497 * Peer clock filter and its helpers
500 filter_datapoints(peer_t *p)
504 double minoff, maxoff, wavg, sum, w;
505 double x = x; /* for compiler */
506 double oldest_off = oldest_off;
507 double oldest_age = oldest_age;
508 double newest_off = newest_off;
509 double newest_age = newest_age;
511 minoff = maxoff = p->filter_datapoint[0].d_offset;
512 for (i = 1; i < NUM_DATAPOINTS; i++) {
513 if (minoff > p->filter_datapoint[i].d_offset)
514 minoff = p->filter_datapoint[i].d_offset;
515 if (maxoff < p->filter_datapoint[i].d_offset)
516 maxoff = p->filter_datapoint[i].d_offset;
519 idx = p->datapoint_idx; /* most recent datapoint */
521 * Drop two outliers and take weighted average of the rest:
522 * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
523 * we use older6/32, not older6/64 since sum of weights should be 1:
524 * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
530 * filter_dispersion = \ -------------
537 for (i = 0; i < NUM_DATAPOINTS; i++) {
539 bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
541 p->filter_datapoint[idx].d_offset,
542 p->filter_datapoint[idx].d_dispersion, dispersion(&p->filter_datapoint[idx]),
543 G.cur_time - p->filter_datapoint[idx].d_recv_time,
544 (minoff == p->filter_datapoint[idx].d_offset || maxoff == p->filter_datapoint[idx].d_offset)
545 ? " (outlier by offset)" : ""
549 sum += dispersion(&p->filter_datapoint[idx]) / (2 << i);
551 if (minoff == p->filter_datapoint[idx].d_offset) {
552 minoff -= 1; /* so that we don't match it ever again */
554 if (maxoff == p->filter_datapoint[idx].d_offset) {
557 oldest_off = p->filter_datapoint[idx].d_offset;
558 oldest_age = G.cur_time - p->filter_datapoint[idx].d_recv_time;
561 newest_off = oldest_off;
562 newest_age = oldest_age;
569 idx = (idx - 1) & (NUM_DATAPOINTS - 1);
571 p->filter_dispersion = sum;
572 wavg += x; /* add another older6/64 to form older6/32 */
573 /* Fix systematic underestimation with large poll intervals.
574 * Imagine that we still have a bit of uncorrected drift,
575 * and poll interval is big (say, 100 sec). Offsets form a progression:
576 * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
577 * The algorithm above drops 0.0 and 0.7 as outliers,
578 * and then we have this estimation, ~25% off from 0.7:
579 * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
581 x = oldest_age - newest_age;
583 x = newest_age / x; /* in above example, 100 / (600 - 100) */
584 if (x < 1) { /* paranoia check */
585 x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
589 p->filter_offset = wavg;
591 /* +----- -----+ ^ 1/2
595 * filter_jitter = | --- * / (avg-offset_j) |
599 * where n is the number of valid datapoints in the filter (n > 1);
600 * if filter_jitter < precision then filter_jitter = precision
603 for (i = 0; i < NUM_DATAPOINTS; i++) {
604 sum += SQUARE(wavg - p->filter_datapoint[i].d_offset);
606 sum = SQRT(sum / NUM_DATAPOINTS);
607 p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
609 VERB3 bb_error_msg("filter offset:%+f(corr:%e) disp:%f jitter:%f",
611 p->filter_dispersion,
616 reset_peer_stats(peer_t *p, double offset)
619 bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
621 for (i = 0; i < NUM_DATAPOINTS; i++) {
623 p->filter_datapoint[i].d_recv_time += offset;
624 if (p->filter_datapoint[i].d_offset != 0) {
625 p->filter_datapoint[i].d_offset -= offset;
626 //bb_error_msg("p->filter_datapoint[%d].d_offset %f -> %f",
628 // p->filter_datapoint[i].d_offset + offset,
629 // p->filter_datapoint[i].d_offset);
632 p->filter_datapoint[i].d_recv_time = G.cur_time;
633 p->filter_datapoint[i].d_offset = 0;
634 p->filter_datapoint[i].d_dispersion = MAXDISP;
638 p->lastpkt_recv_time += offset;
640 p->reachable_bits = 0;
641 p->lastpkt_recv_time = G.cur_time;
643 filter_datapoints(p); /* recalc p->filter_xxx */
644 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
652 p = xzalloc(sizeof(*p));
653 p->p_lsa = xhost2sockaddr(s, 123);
654 p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
656 p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
657 p->next_action_time = G.cur_time; /* = set_next(p, 0); */
658 reset_peer_stats(p, 16 * STEP_THRESHOLD);
660 llist_add_to(&G.ntp_peers, p);
666 const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
667 msg_t *msg, ssize_t len)
673 ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
675 ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
678 bb_perror_msg("send failed");
685 send_query_to_peer(peer_t *p)
687 /* Why do we need to bind()?
688 * See what happens when we don't bind:
690 * socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
691 * setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
692 * gettimeofday({1259071266, 327885}, NULL) = 0
693 * sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
694 * ^^^ we sent it from some source port picked by kernel.
695 * time(NULL) = 1259071266
696 * write(2, "ntpd: entering poll 15 secs\n", 28) = 28
697 * poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
698 * recv(3, "yyy", 68, MSG_DONTWAIT) = 48
699 * ^^^ this recv will receive packets to any local port!
701 * Uncomment this and use strace to see it in action:
703 #define PROBE_LOCAL_ADDR /* { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } */
707 len_and_sockaddr *local_lsa;
709 family = p->p_lsa->u.sa.sa_family;
710 p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
711 /* local_lsa has "null" address and port 0 now.
712 * bind() ensures we have a *particular port* selected by kernel
713 * and remembered in p->p_fd, thus later recv(p->p_fd)
714 * receives only packets sent to this port.
717 xbind(fd, &local_lsa->u.sa, local_lsa->len);
719 #if ENABLE_FEATURE_IPV6
720 if (family == AF_INET)
722 setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
727 * Send out a random 64-bit number as our transmit time. The NTP
728 * server will copy said number into the originate field on the
729 * response that it sends us. This is totally legal per the SNTP spec.
731 * The impact of this is two fold: we no longer send out the current
732 * system time for the world to see (which may aid an attacker), and
733 * it gives us a (not very secure) way of knowing that we're not
734 * getting spoofed by an attacker that can't capture our traffic
735 * but can spoof packets from the NTP server we're communicating with.
737 * Save the real transmit timestamp locally.
739 p->p_xmt_msg.m_xmttime.int_partl = random();
740 p->p_xmt_msg.m_xmttime.fractionl = random();
741 p->p_xmttime = gettime1900d();
743 if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
744 &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
748 set_next(p, RETRY_INTERVAL);
752 p->reachable_bits <<= 1;
753 VERB1 bb_error_msg("sent query to %s", p->p_dotted);
754 set_next(p, RESPONSE_INTERVAL);
758 /* Note that there is no provision to prevent several run_scripts
759 * to be done in quick succession. In fact, it happens rather often
760 * if initial syncronization results in a step.
761 * You will see "step" and then "stratum" script runs, sometimes
762 * as close as only 0.002 seconds apart.
763 * Script should be ready to deal with this.
765 static void run_script(const char *action, double offset)
768 char *env1, *env2, *env3, *env4;
773 argv[0] = (char*) G.script_name;
774 argv[1] = (char*) action;
777 VERB1 bb_error_msg("executing '%s %s'", G.script_name, action);
779 env1 = xasprintf("%s=%u", "stratum", G.stratum);
781 env2 = xasprintf("%s=%ld", "freq_drift_ppm", G.kernel_freq_drift);
783 env3 = xasprintf("%s=%u", "poll_interval", 1 << G.poll_exp);
785 env4 = xasprintf("%s=%f", "offset", offset);
787 /* Other items of potential interest: selected peer,
788 * rootdelay, reftime, rootdisp, refid, ntp_status,
789 * last_update_offset, last_update_recv_time, discipline_jitter,
790 * how many peers have reachable_bits = 0?
793 /* Don't want to wait: it may run hwclock --systohc, and that
794 * may take some time (seconds): */
795 /*spawn_and_wait(argv);*/
799 unsetenv("freq_drift_ppm");
800 unsetenv("poll_interval");
807 G.last_script_run = G.cur_time;
811 step_time(double offset)
815 struct timeval tvc, tvn;
816 char buf[sizeof("yyyy-mm-dd hh:mm:ss") + /*paranoia:*/ 4];
819 gettimeofday(&tvc, NULL); /* never fails */
820 dtime = tvc.tv_sec + (1.0e-6 * tvc.tv_usec) + offset;
821 d_to_tv(dtime, &tvn);
822 if (settimeofday(&tvn, NULL) == -1)
823 bb_perror_msg_and_die("settimeofday");
827 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
828 bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
831 strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
832 bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
834 /* Correct various fields which contain time-relative values: */
836 /* p->lastpkt_recv_time, p->next_action_time and such: */
837 for (item = G.ntp_peers; item != NULL; item = item->link) {
838 peer_t *pp = (peer_t *) item->data;
839 reset_peer_stats(pp, offset);
840 //bb_error_msg("offset:%+f pp->next_action_time:%f -> %f",
841 // offset, pp->next_action_time, pp->next_action_time + offset);
842 pp->next_action_time += offset;
845 G.cur_time += offset;
846 G.last_update_recv_time += offset;
847 G.last_script_run += offset;
852 * Selection and clustering, and their helpers
858 double opt_rd; /* optimization */
861 compare_point_edge(const void *aa, const void *bb)
863 const point_t *a = aa;
864 const point_t *b = bb;
865 if (a->edge < b->edge) {
868 return (a->edge > b->edge);
875 compare_survivor_metric(const void *aa, const void *bb)
877 const survivor_t *a = aa;
878 const survivor_t *b = bb;
879 if (a->metric < b->metric) {
882 return (a->metric > b->metric);
885 fit(peer_t *p, double rd)
887 if ((p->reachable_bits & (p->reachable_bits-1)) == 0) {
888 /* One or zero bits in reachable_bits */
889 VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
892 #if 0 /* we filter out such packets earlier */
893 if ((p->lastpkt_status & LI_ALARM) == LI_ALARM
894 || p->lastpkt_stratum >= MAXSTRAT
896 VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
900 /* rd is root_distance(p) */
901 if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
902 VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
906 // /* Do we have a loop? */
907 // if (p->refid == p->dstaddr || p->refid == s.refid)
912 select_and_cluster(void)
917 int size = 3 * G.peer_cnt;
918 /* for selection algorithm */
920 unsigned num_points, num_candidates;
922 unsigned num_falsetickers;
923 /* for cluster algorithm */
924 survivor_t survivor[size];
925 unsigned num_survivors;
931 if (G.initial_poll_complete) while (item != NULL) {
934 p = (peer_t *) item->data;
935 rd = root_distance(p);
936 offset = p->filter_offset;
942 VERB4 bb_error_msg("interval: [%f %f %f] %s",
948 point[num_points].p = p;
949 point[num_points].type = -1;
950 point[num_points].edge = offset - rd;
951 point[num_points].opt_rd = rd;
953 point[num_points].p = p;
954 point[num_points].type = 0;
955 point[num_points].edge = offset;
956 point[num_points].opt_rd = rd;
958 point[num_points].p = p;
959 point[num_points].type = 1;
960 point[num_points].edge = offset + rd;
961 point[num_points].opt_rd = rd;
965 num_candidates = num_points / 3;
966 if (num_candidates == 0) {
967 VERB3 bb_error_msg("no valid datapoints, no peer selected");
970 //TODO: sorting does not seem to be done in reference code
971 qsort(point, num_points, sizeof(point[0]), compare_point_edge);
973 /* Start with the assumption that there are no falsetickers.
974 * Attempt to find a nonempty intersection interval containing
975 * the midpoints of all truechimers.
976 * If a nonempty interval cannot be found, increase the number
977 * of assumed falsetickers by one and try again.
978 * If a nonempty interval is found and the number of falsetickers
979 * is less than the number of truechimers, a majority has been found
980 * and the midpoint of each truechimer represents
981 * the candidates available to the cluster algorithm.
983 num_falsetickers = 0;
986 unsigned num_midpoints = 0;
991 for (i = 0; i < num_points; i++) {
993 * if (point[i].type == -1) c++;
994 * if (point[i].type == 1) c--;
995 * and it's simpler to do it this way:
998 if (c >= num_candidates - num_falsetickers) {
999 /* If it was c++ and it got big enough... */
1000 low = point[i].edge;
1003 if (point[i].type == 0)
1007 for (i = num_points-1; i >= 0; i--) {
1009 if (c >= num_candidates - num_falsetickers) {
1010 high = point[i].edge;
1013 if (point[i].type == 0)
1016 /* If the number of midpoints is greater than the number
1017 * of allowed falsetickers, the intersection contains at
1018 * least one truechimer with no midpoint - bad.
1019 * Also, interval should be nonempty.
1021 if (num_midpoints <= num_falsetickers && low < high)
1024 if (num_falsetickers * 2 >= num_candidates) {
1025 VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected",
1026 num_falsetickers, num_candidates);
1030 VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
1031 low, high, num_candidates, num_falsetickers);
1035 /* Construct a list of survivors (p, metric)
1036 * from the chime list, where metric is dominated
1037 * first by stratum and then by root distance.
1038 * All other things being equal, this is the order of preference.
1041 for (i = 0; i < num_points; i++) {
1042 if (point[i].edge < low || point[i].edge > high)
1045 survivor[num_survivors].p = p;
1046 /* x.opt_rd == root_distance(p); */
1047 survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + point[i].opt_rd;
1048 VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s",
1049 num_survivors, survivor[num_survivors].metric, p->p_dotted);
1052 /* There must be at least MIN_SELECTED survivors to satisfy the
1053 * correctness assertions. Ordinarily, the Byzantine criteria
1054 * require four survivors, but for the demonstration here, one
1057 if (num_survivors < MIN_SELECTED) {
1058 VERB3 bb_error_msg("num_survivors %d < %d, no peer selected",
1059 num_survivors, MIN_SELECTED);
1063 //looks like this is ONLY used by the fact that later we pick survivor[0].
1064 //we can avoid sorting then, just find the minimum once!
1065 qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric);
1067 /* For each association p in turn, calculate the selection
1068 * jitter p->sjitter as the square root of the sum of squares
1069 * (p->offset - q->offset) over all q associations. The idea is
1070 * to repeatedly discard the survivor with maximum selection
1071 * jitter until a termination condition is met.
1074 unsigned max_idx = max_idx;
1075 double max_selection_jitter = max_selection_jitter;
1076 double min_jitter = min_jitter;
1078 if (num_survivors <= MIN_CLUSTERED) {
1079 VERB3 bb_error_msg("num_survivors %d <= %d, not discarding more",
1080 num_survivors, MIN_CLUSTERED);
1084 /* To make sure a few survivors are left
1085 * for the clustering algorithm to chew on,
1086 * we stop if the number of survivors
1087 * is less than or equal to MIN_CLUSTERED (3).
1089 for (i = 0; i < num_survivors; i++) {
1090 double selection_jitter_sq;
1093 if (i == 0 || p->filter_jitter < min_jitter)
1094 min_jitter = p->filter_jitter;
1096 selection_jitter_sq = 0;
1097 for (j = 0; j < num_survivors; j++) {
1098 peer_t *q = survivor[j].p;
1099 selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
1101 if (i == 0 || selection_jitter_sq > max_selection_jitter) {
1102 max_selection_jitter = selection_jitter_sq;
1105 VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
1106 i, selection_jitter_sq);
1108 max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
1109 VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
1110 max_idx, max_selection_jitter, min_jitter);
1112 /* If the maximum selection jitter is less than the
1113 * minimum peer jitter, then tossing out more survivors
1114 * will not lower the minimum peer jitter, so we might
1117 if (max_selection_jitter < min_jitter) {
1118 VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
1119 max_selection_jitter, min_jitter, num_survivors);
1123 /* Delete survivor[max_idx] from the list
1124 * and go around again.
1126 VERB5 bb_error_msg("dropping survivor %d", max_idx);
1128 while (max_idx < num_survivors) {
1129 survivor[max_idx] = survivor[max_idx + 1];
1135 /* Combine the offsets of the clustering algorithm survivors
1136 * using a weighted average with weight determined by the root
1137 * distance. Compute the selection jitter as the weighted RMS
1138 * difference between the first survivor and the remaining
1139 * survivors. In some cases the inherent clock jitter can be
1140 * reduced by not using this algorithm, especially when frequent
1141 * clockhopping is involved. bbox: thus we don't do it.
1145 for (i = 0; i < num_survivors; i++) {
1147 x = root_distance(p);
1149 z += p->filter_offset / x;
1150 w += SQUARE(p->filter_offset - survivor[0].p->filter_offset) / x;
1152 //G.cluster_offset = z / y;
1153 //G.cluster_jitter = SQRT(w / y);
1156 /* Pick the best clock. If the old system peer is on the list
1157 * and at the same stratum as the first survivor on the list,
1158 * then don't do a clock hop. Otherwise, select the first
1159 * survivor on the list as the new system peer.
1162 if (G.last_update_peer
1163 && G.last_update_peer->lastpkt_stratum <= p->lastpkt_stratum
1165 /* Starting from 1 is ok here */
1166 for (i = 1; i < num_survivors; i++) {
1167 if (G.last_update_peer == survivor[i].p) {
1168 VERB4 bb_error_msg("keeping old synced peer");
1169 p = G.last_update_peer;
1174 G.last_update_peer = p;
1176 VERB3 bb_error_msg("selected peer %s filter_offset:%+f age:%f",
1179 G.cur_time - p->lastpkt_recv_time
1186 * Local clock discipline and its helpers
1189 set_new_values(int disc_state, double offset, double recv_time)
1191 /* Enter new state and set state variables. Note we use the time
1192 * of the last clock filter sample, which must be earlier than
1195 VERB3 bb_error_msg("disc_state=%d last update offset=%f recv_time=%f",
1196 disc_state, offset, recv_time);
1197 G.discipline_state = disc_state;
1198 G.last_update_offset = offset;
1199 G.last_update_recv_time = recv_time;
1201 /* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
1203 update_local_clock(peer_t *p)
1207 /* Note: can use G.cluster_offset instead: */
1208 double offset = p->filter_offset;
1209 double recv_time = p->lastpkt_recv_time;
1211 #if !USING_KERNEL_PLL_LOOP
1214 double since_last_update;
1215 double etemp, dtemp;
1217 abs_offset = fabs(offset);
1220 /* If needed, -S script can do it by looking at $offset
1221 * env var and killing parent */
1222 /* If the offset is too large, give up and go home */
1223 if (abs_offset > PANIC_THRESHOLD) {
1224 bb_error_msg_and_die("offset %f far too big, exiting", offset);
1228 /* If this is an old update, for instance as the result
1229 * of a system peer change, avoid it. We never use
1230 * an old sample or the same sample twice.
1232 if (recv_time <= G.last_update_recv_time) {
1233 VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it",
1234 G.last_update_recv_time, recv_time);
1235 return 0; /* "leave poll interval as is" */
1238 /* Clock state machine transition function. This is where the
1239 * action is and defines how the system reacts to large time
1240 * and frequency errors.
1242 since_last_update = recv_time - G.reftime;
1243 #if !USING_KERNEL_PLL_LOOP
1246 #if USING_INITIAL_FREQ_ESTIMATION
1247 if (G.discipline_state == STATE_FREQ) {
1248 /* Ignore updates until the stepout threshold */
1249 if (since_last_update < WATCH_THRESHOLD) {
1250 VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
1251 WATCH_THRESHOLD - since_last_update);
1252 return 0; /* "leave poll interval as is" */
1254 # if !USING_KERNEL_PLL_LOOP
1255 freq_drift = (offset - G.last_update_offset) / since_last_update;
1260 /* There are two main regimes: when the
1261 * offset exceeds the step threshold and when it does not.
1263 if (abs_offset > STEP_THRESHOLD) {
1264 switch (G.discipline_state) {
1266 /* The first outlyer: ignore it, switch to SPIK state */
1267 VERB3 bb_error_msg("offset:%+f - spike detected", offset);
1268 G.discipline_state = STATE_SPIK;
1269 return -1; /* "decrease poll interval" */
1272 /* Ignore succeeding outlyers until either an inlyer
1273 * is found or the stepout threshold is exceeded.
1275 if (since_last_update < WATCH_THRESHOLD) {
1276 VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains",
1277 WATCH_THRESHOLD - since_last_update);
1278 return -1; /* "decrease poll interval" */
1280 /* fall through: we need to step */
1283 /* Step the time and clamp down the poll interval.
1285 * In NSET state an initial frequency correction is
1286 * not available, usually because the frequency file has
1287 * not yet been written. Since the time is outside the
1288 * capture range, the clock is stepped. The frequency
1289 * will be set directly following the stepout interval.
1291 * In FSET state the initial frequency has been set
1292 * from the frequency file. Since the time is outside
1293 * the capture range, the clock is stepped immediately,
1294 * rather than after the stepout interval. Guys get
1295 * nervous if it takes 17 minutes to set the clock for
1298 * In SPIK state the stepout threshold has expired and
1299 * the phase is still above the step threshold. Note
1300 * that a single spike greater than the step threshold
1301 * is always suppressed, even at the longer poll
1304 VERB3 bb_error_msg("stepping time by %+f; poll_exp=MINPOLL", offset);
1306 if (option_mask32 & OPT_q) {
1307 /* We were only asked to set time once. Done. */
1311 G.polladj_count = 0;
1312 G.poll_exp = MINPOLL;
1313 G.stratum = MAXSTRAT;
1315 run_script("step", offset);
1317 #if USING_INITIAL_FREQ_ESTIMATION
1318 if (G.discipline_state == STATE_NSET) {
1319 set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
1320 return 1; /* "ok to increase poll interval" */
1323 set_new_values(STATE_SYNC, /*offset:*/ 0, recv_time);
1325 } else { /* abs_offset <= STEP_THRESHOLD */
1327 if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
1328 VERB3 bb_error_msg("small offset:%+f, disabling burst mode", offset);
1329 G.polladj_count = 0;
1330 G.poll_exp = MINPOLL;
1333 /* Compute the clock jitter as the RMS of exponentially
1334 * weighted offset differences. Used by the poll adjust code.
1336 etemp = SQUARE(G.discipline_jitter);
1337 dtemp = SQUARE(MAXD(fabs(offset - G.last_update_offset), G_precision_sec));
1338 G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
1339 VERB3 bb_error_msg("discipline jitter=%f", G.discipline_jitter);
1341 switch (G.discipline_state) {
1343 if (option_mask32 & OPT_q) {
1344 /* We were only asked to set time once.
1345 * The clock is precise enough, no need to step.
1349 #if USING_INITIAL_FREQ_ESTIMATION
1350 /* This is the first update received and the frequency
1351 * has not been initialized. The first thing to do
1352 * is directly measure the oscillator frequency.
1354 set_new_values(STATE_FREQ, offset, recv_time);
1356 set_new_values(STATE_SYNC, offset, recv_time);
1358 VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
1359 return 0; /* "leave poll interval as is" */
1361 #if 0 /* this is dead code for now */
1363 /* This is the first update and the frequency
1364 * has been initialized. Adjust the phase, but
1365 * don't adjust the frequency until the next update.
1367 set_new_values(STATE_SYNC, offset, recv_time);
1368 /* freq_drift remains 0 */
1372 #if USING_INITIAL_FREQ_ESTIMATION
1374 /* since_last_update >= WATCH_THRESHOLD, we waited enough.
1375 * Correct the phase and frequency and switch to SYNC state.
1376 * freq_drift was already estimated (see code above)
1378 set_new_values(STATE_SYNC, offset, recv_time);
1383 #if !USING_KERNEL_PLL_LOOP
1384 /* Compute freq_drift due to PLL and FLL contributions.
1386 * The FLL and PLL frequency gain constants
1387 * depend on the poll interval and Allan
1388 * intercept. The FLL is not used below one-half
1389 * the Allan intercept. Above that the loop gain
1390 * increases in steps to 1 / AVG.
1392 if ((1 << G.poll_exp) > ALLAN / 2) {
1393 etemp = FLL - G.poll_exp;
1396 freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp);
1398 /* For the PLL the integration interval
1399 * (numerator) is the minimum of the update
1400 * interval and poll interval. This allows
1401 * oversampling, but not undersampling.
1403 etemp = MIND(since_last_update, (1 << G.poll_exp));
1404 dtemp = (4 * PLL) << G.poll_exp;
1405 freq_drift += offset * etemp / SQUARE(dtemp);
1407 set_new_values(STATE_SYNC, offset, recv_time);
1410 if (G.stratum != p->lastpkt_stratum + 1) {
1411 G.stratum = p->lastpkt_stratum + 1;
1412 run_script("stratum", offset);
1416 G.reftime = G.cur_time;
1417 G.ntp_status = p->lastpkt_status;
1418 G.refid = p->lastpkt_refid;
1419 G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
1420 dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(G.cluster_jitter));
1421 dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time) + abs_offset, MINDISP);
1422 G.rootdisp = p->lastpkt_rootdisp + dtemp;
1423 VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted);
1425 /* We are in STATE_SYNC now, but did not do adjtimex yet.
1426 * (Any other state does not reach this, they all return earlier)
1427 * By this time, freq_drift and G.last_update_offset are set
1428 * to values suitable for adjtimex.
1430 #if !USING_KERNEL_PLL_LOOP
1431 /* Calculate the new frequency drift and frequency stability (wander).
1432 * Compute the clock wander as the RMS of exponentially weighted
1433 * frequency differences. This is not used directly, but can,
1434 * along with the jitter, be a highly useful monitoring and
1437 dtemp = G.discipline_freq_drift + freq_drift;
1438 G.discipline_freq_drift = MAXD(MIND(MAXDRIFT, dtemp), -MAXDRIFT);
1439 etemp = SQUARE(G.discipline_wander);
1440 dtemp = SQUARE(dtemp);
1441 G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
1443 VERB3 bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
1444 G.discipline_freq_drift,
1445 (long)(G.discipline_freq_drift * 65536e6),
1447 G.discipline_wander);
1450 memset(&tmx, 0, sizeof(tmx));
1451 if (adjtimex(&tmx) < 0)
1452 bb_perror_msg_and_die("adjtimex");
1453 VERB3 bb_error_msg("p adjtimex freq:%ld offset:%+ld constant:%ld status:0x%x",
1454 tmx.freq, tmx.offset, tmx.constant, tmx.status);
1457 memset(&tmx, 0, sizeof(tmx));
1459 //doesn't work, offset remains 0 (!) in kernel:
1460 //ntpd: set adjtimex freq:1786097 tmx.offset:77487
1461 //ntpd: prev adjtimex freq:1786097 tmx.offset:0
1462 //ntpd: cur adjtimex freq:1786097 tmx.offset:0
1463 tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET;
1464 /* 65536 is one ppm */
1465 tmx.freq = G.discipline_freq_drift * 65536e6;
1466 tmx.offset = G.last_update_offset * 1000000; /* usec */
1468 tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
1469 tmx.offset = (G.last_update_offset * 1000000); /* usec */
1470 /* + (G.last_update_offset < 0 ? -0.5 : 0.5) - too small to bother */
1471 tmx.status = STA_PLL;
1472 if (G.ntp_status & LI_PLUSSEC)
1473 tmx.status |= STA_INS;
1474 if (G.ntp_status & LI_MINUSSEC)
1475 tmx.status |= STA_DEL;
1476 tmx.constant = G.poll_exp - 4;
1477 //tmx.esterror = (u_int32)(clock_jitter * 1e6);
1478 //tmx.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
1479 rc = adjtimex(&tmx);
1481 bb_perror_msg_and_die("adjtimex");
1482 /* NB: here kernel returns constant == G.poll_exp, not == G.poll_exp - 4.
1483 * Not sure why. Perhaps it is normal.
1485 VERB3 bb_error_msg("adjtimex:%d freq:%ld offset:%+ld constant:%ld status:0x%x",
1486 rc, tmx.freq, tmx.offset, tmx.constant, tmx.status);
1489 /* always gives the same output as above msg */
1490 memset(&tmx, 0, sizeof(tmx));
1491 if (adjtimex(&tmx) < 0)
1492 bb_perror_msg_and_die("adjtimex");
1493 VERB3 bb_error_msg("c adjtimex freq:%ld offset:%+ld constant:%ld status:0x%x",
1494 tmx.freq, tmx.offset, tmx.constant, tmx.status);
1497 G.kernel_freq_drift = tmx.freq / 65536;
1498 VERB2 bb_error_msg("update peer:%s, offset:%+f, clock drift:%+ld ppm",
1499 p->p_dotted, G.last_update_offset, G.kernel_freq_drift);
1501 return 1; /* "ok to increase poll interval" */
1506 * We've got a new reply packet from a peer, process it
1510 retry_interval(void)
1512 /* Local problem, want to retry soon */
1513 unsigned interval, r;
1514 interval = RETRY_INTERVAL;
1516 interval += r % (unsigned)(RETRY_INTERVAL / 4);
1517 VERB3 bb_error_msg("chose retry interval:%u", interval);
1521 poll_interval(int exponent)
1523 unsigned interval, r;
1524 exponent = G.poll_exp + exponent;
1527 interval = 1 << exponent;
1529 interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
1530 VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
1533 static NOINLINE void
1534 recv_and_process_peer_pkt(peer_t *p)
1539 double T1, T2, T3, T4;
1541 datapoint_t *datapoint;
1544 /* We can recvfrom here and check from.IP, but some multihomed
1545 * ntp servers reply from their *other IP*.
1546 * TODO: maybe we should check at least what we can: from.port == 123?
1548 size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
1550 bb_perror_msg("recv(%s) error", p->p_dotted);
1551 if (errno == EHOSTUNREACH || errno == EHOSTDOWN
1552 || errno == ENETUNREACH || errno == ENETDOWN
1553 || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
1556 //TODO: always do this?
1557 interval = retry_interval();
1558 goto set_next_and_close_sock;
1563 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1564 bb_error_msg("malformed packet received from %s", p->p_dotted);
1568 if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
1569 || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
1574 if ((msg.m_status & LI_ALARM) == LI_ALARM
1575 || msg.m_stratum == 0
1576 || msg.m_stratum > NTP_MAXSTRATUM
1578 // TODO: stratum 0 responses may have commands in 32-bit m_refid field:
1579 // "DENY", "RSTR" - peer does not like us at all
1580 // "RATE" - peer is overloaded, reduce polling freq
1581 interval = poll_interval(0);
1582 bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
1583 goto set_next_and_close_sock;
1586 // /* Verify valid root distance */
1587 // if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
1588 // return; /* invalid header values */
1590 p->lastpkt_status = msg.m_status;
1591 p->lastpkt_stratum = msg.m_stratum;
1592 p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
1593 p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
1594 p->lastpkt_refid = msg.m_refid;
1597 * From RFC 2030 (with a correction to the delay math):
1599 * Timestamp Name ID When Generated
1600 * ------------------------------------------------------------
1601 * Originate Timestamp T1 time request sent by client
1602 * Receive Timestamp T2 time request received by server
1603 * Transmit Timestamp T3 time reply sent by server
1604 * Destination Timestamp T4 time reply received by client
1606 * The roundtrip delay and local clock offset are defined as
1608 * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
1611 T2 = lfp_to_d(msg.m_rectime);
1612 T3 = lfp_to_d(msg.m_xmttime);
1615 p->lastpkt_recv_time = T4;
1617 VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
1618 p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
1619 datapoint = &p->filter_datapoint[p->datapoint_idx];
1620 datapoint->d_recv_time = T4;
1621 datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
1622 /* The delay calculation is a special case. In cases where the
1623 * server and client clocks are running at different rates and
1624 * with very fast networks, the delay can appear negative. In
1625 * order to avoid violating the Principle of Least Astonishment,
1626 * the delay is clamped not less than the system precision.
1628 p->lastpkt_delay = (T4 - T1) - (T3 - T2);
1629 if (p->lastpkt_delay < G_precision_sec)
1630 p->lastpkt_delay = G_precision_sec;
1631 datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
1632 if (!p->reachable_bits) {
1633 /* 1st datapoint ever - replicate offset in every element */
1635 for (i = 1; i < NUM_DATAPOINTS; i++) {
1636 p->filter_datapoint[i].d_offset = datapoint->d_offset;
1640 p->reachable_bits |= 1;
1641 if ((MAX_VERBOSE && G.verbose) || (option_mask32 & OPT_w)) {
1642 bb_error_msg("reply from %s: reach 0x%02x offset %+f delay %f status 0x%02x strat %d refid 0x%08x rootdelay %f",
1645 datapoint->d_offset,
1650 p->lastpkt_rootdelay
1651 /* not shown: m_ppoll, m_precision_exp, m_rootdisp,
1652 * m_reftime, m_orgtime, m_rectime, m_xmttime
1657 /* Muck with statictics and update the clock */
1658 filter_datapoints(p);
1659 q = select_and_cluster();
1663 if (!(option_mask32 & OPT_w)) {
1664 rc = update_local_clock(q);
1665 /* If drift is dangerously large, immediately
1666 * drop poll interval one step down.
1668 if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) {
1669 VERB3 bb_error_msg("offset:%+f > POLLDOWN_OFFSET", q->filter_offset);
1674 /* else: no peer selected, rc = -1: we want to poll more often */
1677 /* Adjust the poll interval by comparing the current offset
1678 * with the clock jitter. If the offset is less than
1679 * the clock jitter times a constant, then the averaging interval
1680 * is increased, otherwise it is decreased. A bit of hysteresis
1681 * helps calm the dance. Works best using burst mode.
1684 bb_error_msg("offset:%+f POLLADJ_GATE*discipline_jitter:%f poll:%s",
1685 q->filter_offset, POLLADJ_GATE * G.discipline_jitter,
1686 fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter
1690 if (rc > 0 && fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter) {
1691 /* was += G.poll_exp but it is a bit
1692 * too optimistic for my taste at high poll_exp's */
1693 G.polladj_count += MINPOLL;
1694 if (G.polladj_count > POLLADJ_LIMIT) {
1695 G.polladj_count = 0;
1696 if (G.poll_exp < MAXPOLL) {
1698 VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
1699 G.discipline_jitter, G.poll_exp);
1702 VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count);
1705 G.polladj_count -= G.poll_exp * 2;
1706 if (G.polladj_count < -POLLADJ_LIMIT || G.poll_exp >= BIGPOLL) {
1708 G.polladj_count = 0;
1709 if (G.poll_exp > MINPOLL) {
1713 /* Correct p->next_action_time in each peer
1714 * which waits for sending, so that they send earlier.
1715 * Old pp->next_action_time are on the order
1716 * of t + (1 << old_poll_exp) + small_random,
1717 * we simply need to subtract ~half of that.
1719 for (item = G.ntp_peers; item != NULL; item = item->link) {
1720 peer_t *pp = (peer_t *) item->data;
1722 pp->next_action_time -= (1 << G.poll_exp);
1724 VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
1725 G.discipline_jitter, G.poll_exp);
1728 VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count);
1733 /* Decide when to send new query for this peer */
1734 interval = poll_interval(0);
1736 set_next_and_close_sock:
1737 set_next(p, interval);
1738 /* We do not expect any more packets from this peer for now.
1739 * Closing the socket informs kernel about it.
1740 * We open a new socket when we send a new query.
1748 #if ENABLE_FEATURE_NTPD_SERVER
1749 static NOINLINE void
1750 recv_and_process_client_pkt(void /*int fd*/)
1754 len_and_sockaddr *to;
1755 struct sockaddr *from;
1757 uint8_t query_status;
1758 l_fixedpt_t query_xmttime;
1760 to = get_sock_lsa(G.listen_fd);
1761 from = xzalloc(to->len);
1763 size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
1764 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
1767 if (errno == EAGAIN)
1769 bb_perror_msg_and_die("recv");
1771 addr = xmalloc_sockaddr2dotted_noport(from);
1772 bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
1777 query_status = msg.m_status;
1778 query_xmttime = msg.m_xmttime;
1780 /* Build a reply packet */
1781 memset(&msg, 0, sizeof(msg));
1782 msg.m_status = G.stratum < MAXSTRAT ? G.ntp_status : LI_ALARM;
1783 msg.m_status |= (query_status & VERSION_MASK);
1784 msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
1785 MODE_SERVER : MODE_SYM_PAS;
1786 msg.m_stratum = G.stratum;
1787 msg.m_ppoll = G.poll_exp;
1788 msg.m_precision_exp = G_precision_exp;
1789 /* this time was obtained between poll() and recv() */
1790 msg.m_rectime = d_to_lfp(G.cur_time);
1791 msg.m_xmttime = d_to_lfp(gettime1900d()); /* this instant */
1792 if (G.peer_cnt == 0) {
1793 /* we have no peers: "stratum 1 server" mode. reftime = our own time */
1794 G.reftime = G.cur_time;
1796 msg.m_reftime = d_to_lfp(G.reftime);
1797 msg.m_orgtime = query_xmttime;
1798 msg.m_rootdelay = d_to_sfp(G.rootdelay);
1799 //simple code does not do this, fix simple code!
1800 msg.m_rootdisp = d_to_sfp(G.rootdisp);
1801 //version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
1802 msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3;
1804 /* We reply from the local address packet was sent to,
1805 * this makes to/from look swapped here: */
1806 do_sendto(G.listen_fd,
1807 /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
1816 /* Upstream ntpd's options:
1818 * -4 Force DNS resolution of host names to the IPv4 namespace.
1819 * -6 Force DNS resolution of host names to the IPv6 namespace.
1820 * -a Require cryptographic authentication for broadcast client,
1821 * multicast client and symmetric passive associations.
1822 * This is the default.
1823 * -A Do not require cryptographic authentication for broadcast client,
1824 * multicast client and symmetric passive associations.
1825 * This is almost never a good idea.
1826 * -b Enable the client to synchronize to broadcast servers.
1828 * Specify the name and path of the configuration file,
1829 * default /etc/ntp.conf
1830 * -d Specify debugging mode. This option may occur more than once,
1831 * with each occurrence indicating greater detail of display.
1833 * Specify debugging level directly.
1835 * Specify the name and path of the frequency file.
1836 * This is the same operation as the "driftfile FILE"
1837 * configuration command.
1838 * -g Normally, ntpd exits with a message to the system log
1839 * if the offset exceeds the panic threshold, which is 1000 s
1840 * by default. This option allows the time to be set to any value
1841 * without restriction; however, this can happen only once.
1842 * If the threshold is exceeded after that, ntpd will exit
1843 * with a message to the system log. This option can be used
1844 * with the -q and -x options. See the tinker command for other options.
1846 * Chroot the server to the directory jaildir. This option also implies
1847 * that the server attempts to drop root privileges at startup
1848 * (otherwise, chroot gives very little additional security).
1849 * You may need to also specify a -u option.
1851 * Specify the name and path of the symmetric key file,
1852 * default /etc/ntp/keys. This is the same operation
1853 * as the "keys FILE" configuration command.
1855 * Specify the name and path of the log file. The default
1856 * is the system log file. This is the same operation as
1857 * the "logfile FILE" configuration command.
1858 * -L Do not listen to virtual IPs. The default is to listen.
1860 * -N To the extent permitted by the operating system,
1861 * run the ntpd at the highest priority.
1863 * Specify the name and path of the file used to record the ntpd
1864 * process ID. This is the same operation as the "pidfile FILE"
1865 * configuration command.
1867 * To the extent permitted by the operating system,
1868 * run the ntpd at the specified priority.
1869 * -q Exit the ntpd just after the first time the clock is set.
1870 * This behavior mimics that of the ntpdate program, which is
1871 * to be retired. The -g and -x options can be used with this option.
1872 * Note: The kernel time discipline is disabled with this option.
1874 * Specify the default propagation delay from the broadcast/multicast
1875 * server to this client. This is necessary only if the delay
1876 * cannot be computed automatically by the protocol.
1878 * Specify the directory path for files created by the statistics
1879 * facility. This is the same operation as the "statsdir DIR"
1880 * configuration command.
1882 * Add a key number to the trusted key list. This option can occur
1885 * Specify a user, and optionally a group, to switch to.
1888 * Add a system variable listed by default.
1889 * -x Normally, the time is slewed if the offset is less than the step
1890 * threshold, which is 128 ms by default, and stepped if above
1891 * the threshold. This option sets the threshold to 600 s, which is
1892 * well within the accuracy window to set the clock manually.
1893 * Note: since the slew rate of typical Unix kernels is limited
1894 * to 0.5 ms/s, each second of adjustment requires an amortization
1895 * interval of 2000 s. Thus, an adjustment as much as 600 s
1896 * will take almost 14 days to complete. This option can be used
1897 * with the -g and -q options. See the tinker command for other options.
1898 * Note: The kernel time discipline is disabled with this option.
1901 /* By doing init in a separate function we decrease stack usage
1904 static NOINLINE void ntp_init(char **argv)
1912 bb_error_msg_and_die(bb_msg_you_must_be_root);
1914 /* Set some globals */
1915 G.stratum = MAXSTRAT;
1917 G.poll_exp = BURSTPOLL; /* speeds up initial sync */
1918 G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
1922 opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
1923 opts = getopt32(argv,
1925 "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
1927 "46aAbgL", /* compat, ignored */
1928 &peers, &G.script_name, &G.verbose);
1929 if (!(opts & (OPT_p|OPT_l)))
1931 // if (opts & OPT_x) /* disable stepping, only slew is allowed */
1932 // G.time_was_stepped = 1;
1935 add_peers(llist_pop(&peers));
1937 /* -l but no peers: "stratum 1 server" mode */
1940 if (!(opts & OPT_n)) {
1941 bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
1942 logmode = LOGMODE_NONE;
1944 #if ENABLE_FEATURE_NTPD_SERVER
1947 G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
1948 socket_want_pktinfo(G.listen_fd);
1949 setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
1952 /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
1954 setpriority(PRIO_PROCESS, 0, -15);
1956 /* If network is up, syncronization occurs in ~10 seconds.
1957 * We give "ntpd -q" 10 seconds to get first reply,
1958 * then another 50 seconds to finish syncing.
1960 * I tested ntpd 4.2.6p1 and apparently it never exits
1961 * (will try forever), but it does not feel right.
1962 * The goal of -q is to act like ntpdate: set time
1963 * after a reasonably small period of polling, or fail.
1966 option_mask32 |= OPT_qq;
1983 int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
1984 int ntpd_main(int argc UNUSED_PARAM, char **argv)
1992 memset(&G, 0, sizeof(G));
1993 SET_PTR_TO_GLOBALS(&G);
1997 /* If ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
1998 cnt = G.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
1999 idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
2000 pfd = xzalloc(sizeof(pfd[0]) * cnt);
2002 /* Countdown: we never sync before we sent INITIAL_SAMPLES+1
2003 * packets to each peer.
2004 * NB: if some peer is not responding, we may end up sending
2005 * fewer packets to it and more to other peers.
2006 * NB2: sync usually happens using INITIAL_SAMPLES packets,
2007 * since last reply does not come back instantaneously.
2009 cnt = G.peer_cnt * (INITIAL_SAMPLES + 1);
2011 while (!bb_got_signal) {
2017 /* Nothing between here and poll() blocks for any significant time */
2019 nextaction = G.cur_time + 3600;
2022 #if ENABLE_FEATURE_NTPD_SERVER
2023 if (G.listen_fd != -1) {
2024 pfd[0].fd = G.listen_fd;
2025 pfd[0].events = POLLIN;
2029 /* Pass over peer list, send requests, time out on receives */
2030 for (item = G.ntp_peers; item != NULL; item = item->link) {
2031 peer_t *p = (peer_t *) item->data;
2033 if (p->next_action_time <= G.cur_time) {
2034 if (p->p_fd == -1) {
2035 /* Time to send new req */
2037 G.initial_poll_complete = 1;
2039 send_query_to_peer(p);
2041 /* Timed out waiting for reply */
2044 timeout = poll_interval(-2); /* -2: try a bit sooner */
2045 bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
2046 p->p_dotted, p->reachable_bits, timeout);
2047 set_next(p, timeout);
2051 if (p->next_action_time < nextaction)
2052 nextaction = p->next_action_time;
2055 /* Wait for reply from this peer */
2056 pfd[i].fd = p->p_fd;
2057 pfd[i].events = POLLIN;
2063 timeout = nextaction - G.cur_time;
2066 timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
2068 /* Here we may block */
2069 VERB2 bb_error_msg("poll %us, sockets:%u, poll interval:%us", timeout, i, 1 << G.poll_exp);
2070 nfds = poll(pfd, i, timeout * 1000);
2071 gettime1900d(); /* sets G.cur_time */
2073 if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
2074 /* Useful for updating battery-backed RTC and such */
2075 run_script("periodic", G.last_update_offset);
2076 gettime1900d(); /* sets G.cur_time */
2081 /* Process any received packets */
2083 #if ENABLE_FEATURE_NTPD_SERVER
2084 if (G.listen_fd != -1) {
2085 if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
2087 recv_and_process_client_pkt(/*G.listen_fd*/);
2088 gettime1900d(); /* sets G.cur_time */
2093 for (; nfds != 0 && j < i; j++) {
2094 if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
2096 * At init, alarm was set to 10 sec.
2097 * Now we did get a reply.
2098 * Increase timeout to 50 seconds to finish syncing.
2100 if (option_mask32 & OPT_qq) {
2101 option_mask32 &= ~OPT_qq;
2105 recv_and_process_peer_pkt(idx2peer[j]);
2106 gettime1900d(); /* sets G.cur_time */
2109 } /* while (!bb_got_signal) */
2111 kill_myself_with_sig(bb_got_signal);
2119 /*** openntpd-4.6 uses only adjtime, not adjtimex ***/
2121 /*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/
2125 direct_freq(double fp_offset)
2129 * If the kernel is enabled, we need the residual offset to
2130 * calculate the frequency correction.
2132 if (pll_control && kern_enable) {
2133 memset(&ntv, 0, sizeof(ntv));
2136 clock_offset = ntv.offset / 1e9;
2137 #else /* STA_NANO */
2138 clock_offset = ntv.offset / 1e6;
2139 #endif /* STA_NANO */
2140 drift_comp = FREQTOD(ntv.freq);
2142 #endif /* KERNEL_PLL */
2143 set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp);
2149 set_freq(double freq) /* frequency update */
2157 * If the kernel is enabled, update the kernel frequency.
2159 if (pll_control && kern_enable) {
2160 memset(&ntv, 0, sizeof(ntv));
2161 ntv.modes = MOD_FREQUENCY;
2162 ntv.freq = DTOFREQ(drift_comp);
2164 snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6);
2165 report_event(EVNT_FSET, NULL, tbuf);
2167 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2168 report_event(EVNT_FSET, NULL, tbuf);
2170 #else /* KERNEL_PLL */
2171 snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
2172 report_event(EVNT_FSET, NULL, tbuf);
2173 #endif /* KERNEL_PLL */
2182 * This code segment works when clock adjustments are made using
2183 * precision time kernel support and the ntp_adjtime() system
2184 * call. This support is available in Solaris 2.6 and later,
2185 * Digital Unix 4.0 and later, FreeBSD, Linux and specially
2186 * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
2187 * DECstation 5000/240 and Alpha AXP, additional kernel
2188 * modifications provide a true microsecond clock and nanosecond
2189 * clock, respectively.
2191 * Important note: The kernel discipline is used only if the
2192 * step threshold is less than 0.5 s, as anything higher can
2193 * lead to overflow problems. This might occur if some misguided
2194 * lad set the step threshold to something ridiculous.
2196 if (pll_control && kern_enable) {
2198 #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST)
2201 * We initialize the structure for the ntp_adjtime()
2202 * system call. We have to convert everything to
2203 * microseconds or nanoseconds first. Do not update the
2204 * system variables if the ext_enable flag is set. In
2205 * this case, the external clock driver will update the
2206 * variables, which will be read later by the local
2207 * clock driver. Afterwards, remember the time and
2208 * frequency offsets for jitter and stability values and
2209 * to update the frequency file.
2211 memset(&ntv, 0, sizeof(ntv));
2213 ntv.modes = MOD_STATUS;
2216 ntv.modes = MOD_BITS | MOD_NANO;
2217 #else /* STA_NANO */
2218 ntv.modes = MOD_BITS;
2219 #endif /* STA_NANO */
2220 if (clock_offset < 0)
2225 ntv.offset = (int32)(clock_offset * 1e9 + dtemp);
2226 ntv.constant = sys_poll;
2227 #else /* STA_NANO */
2228 ntv.offset = (int32)(clock_offset * 1e6 + dtemp);
2229 ntv.constant = sys_poll - 4;
2230 #endif /* STA_NANO */
2231 ntv.esterror = (u_int32)(clock_jitter * 1e6);
2232 ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
2233 ntv.status = STA_PLL;
2236 * Enable/disable the PPS if requested.
2239 if (!(pll_status & STA_PPSTIME))
2240 report_event(EVNT_KERN,
2241 NULL, "PPS enabled");
2242 ntv.status |= STA_PPSTIME | STA_PPSFREQ;
2244 if (pll_status & STA_PPSTIME)
2245 report_event(EVNT_KERN,
2246 NULL, "PPS disabled");
2247 ntv.status &= ~(STA_PPSTIME |
2250 if (sys_leap == LEAP_ADDSECOND)
2251 ntv.status |= STA_INS;
2252 else if (sys_leap == LEAP_DELSECOND)
2253 ntv.status |= STA_DEL;
2257 * Pass the stuff to the kernel. If it squeals, turn off
2258 * the pps. In any case, fetch the kernel offset,
2259 * frequency and jitter.
2261 if (ntp_adjtime(&ntv) == TIME_ERROR) {
2262 if (!(ntv.status & STA_PPSSIGNAL))
2263 report_event(EVNT_KERN, NULL,
2266 pll_status = ntv.status;
2268 clock_offset = ntv.offset / 1e9;
2269 #else /* STA_NANO */
2270 clock_offset = ntv.offset / 1e6;
2271 #endif /* STA_NANO */
2272 clock_frequency = FREQTOD(ntv.freq);
2275 * If the kernel PPS is lit, monitor its performance.
2277 if (ntv.status & STA_PPSTIME) {
2279 clock_jitter = ntv.jitter / 1e9;
2280 #else /* STA_NANO */
2281 clock_jitter = ntv.jitter / 1e6;
2282 #endif /* STA_NANO */
2285 #if defined(STA_NANO) && NTP_API == 4
2287 * If the TAI changes, update the kernel TAI.
2289 if (loop_tai != sys_tai) {
2291 ntv.modes = MOD_TAI;
2292 ntv.constant = sys_tai;
2295 #endif /* STA_NANO */
2297 #endif /* KERNEL_PLL */