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 tarball for details.
9 #include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
10 #ifndef IPTOS_LOWDELAY
11 # define IPTOS_LOWDELAY 0x10
14 # error "Sorry, your kernel has to support IP_PKTINFO"
18 /* Sync to peers every N secs */
19 #define INTERVAL_QUERY_NORMAL 30
20 #define INTERVAL_QUERY_PATHETIC 60
21 #define INTERVAL_QUERY_AGRESSIVE 5
23 /* Bad if *less than* TRUSTLEVEL_BADPEER */
24 #define TRUSTLEVEL_BADPEER 6
25 #define TRUSTLEVEL_PATHETIC 2
26 #define TRUSTLEVEL_AGRESSIVE 8
27 #define TRUSTLEVEL_MAX 10
29 #define QSCALE_OFF_MIN 0.05
30 #define QSCALE_OFF_MAX 0.50
32 /* Single query might take n secs max */
33 #define QUERYTIME_MAX 15
34 /* Min offset for settime at start. "man ntpd" says it's 128 ms */
35 #define STEPTIME_MIN_OFFSET 0.128
49 NTP_MSGSIZE_NOAUTH = 48,
50 NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
54 uint8_t m_status; /* status of local clock and leap info */
55 uint8_t m_stratum; /* stratum level */
56 uint8_t m_ppoll; /* poll value */
58 s_fixedpt_t m_rootdelay;
59 s_fixedpt_t m_dispersion;
61 l_fixedpt_t m_reftime;
62 l_fixedpt_t m_orgtime;
63 l_fixedpt_t m_rectime;
64 l_fixedpt_t m_xmttime;
66 uint8_t m_digest[NTP_DIGESTSIZE];
72 /* Leap Second Codes (high order two bits of m_status) */
73 LI_NOWARNING = (0 << 6), /* no warning */
74 LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
75 LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
76 LI_ALARM = (3 << 6), /* alarm condition */
80 VERSION_MASK = (7 << 3),
85 MODE_RES0 = 0, /* reserved */
86 MODE_SYM_ACT = 1, /* symmetric active */
87 MODE_SYM_PAS = 2, /* symmetric passive */
88 MODE_CLIENT = 3, /* client */
89 MODE_SERVER = 4, /* server */
90 MODE_BROADCAST = 5, /* broadcast */
91 MODE_RES1 = 6, /* reserved for NTP control message */
92 MODE_RES2 = 7, /* reserved for private use */
95 #define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
100 //UNUSED: double o_error;
108 #define OFFSET_ARRAY_SIZE 8
110 len_and_sockaddr *lsa;
113 /* When to send new query (if fd == -1)
114 * or when receive times out (if fd >= 0): */
115 time_t next_action_time;
122 ntp_offset_t reply[OFFSET_ARRAY_SIZE];
130 /* Insert new options above this line. */
131 /* Non-compat options: */
133 OPT_l = (1 << 5) * ENABLE_FEATURE_NTPD_SERVER,
141 #if ENABLE_FEATURE_NTPD_SERVER
151 #define G_precision -6
154 uint8_t time_is_stepped;
155 uint8_t first_adj_done;
157 #define G (*ptr_to_globals)
160 static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
164 set_next(ntp_peer_t *p, unsigned t)
166 p->next_action_time = time(NULL) + t;
174 p = xzalloc(sizeof(*p));
178 p->msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
179 p->trustlevel = TRUSTLEVEL_PATHETIC;
180 p->next_action_time = time(NULL); /* = set_next(p, 0); */
182 llist_add_to(&G.ntp_peers, p);
190 gettimeofday(&tv, NULL); /* never fails */
191 return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970);
195 d_to_tv(double d, struct timeval *tv)
197 tv->tv_sec = (long)d;
198 tv->tv_usec = (d - tv->tv_sec) * 1000000;
202 lfp_to_d(l_fixedpt_t lfp)
205 lfp.int_partl = ntohl(lfp.int_partl);
206 lfp.fractionl = ntohl(lfp.fractionl);
207 ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
213 sfp_to_d(s_fixedpt_t sfp)
216 sfp.int_parts = ntohs(sfp.int_parts);
217 sfp.fractions = ntohs(sfp.fractions);
218 ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
223 #if ENABLE_FEATURE_NTPD_SERVER
228 lfp.int_partl = (uint32_t)d;
229 lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
230 lfp.int_partl = htonl(lfp.int_partl);
231 lfp.fractionl = htonl(lfp.fractionl);
239 sfp.int_parts = (uint16_t)d;
240 sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
241 sfp.int_parts = htons(sfp.int_parts);
242 sfp.fractions = htons(sfp.fractions);
250 unsigned interval, r;
251 interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN;
252 r = (unsigned)random() % (unsigned)(interval / 10);
253 return (interval + r);
258 const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
259 ntp_msg_t *msg, ssize_t len)
265 ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
267 ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
270 bb_perror_msg("send failed");
277 send_query_to_peer(ntp_peer_t *p)
279 // Why do we need to bind()?
280 // See what happens when we don't bind:
282 // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
283 // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
284 // gettimeofday({1259071266, 327885}, NULL) = 0
285 // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
286 // ^^^ we sent it from some source port picked by kernel.
287 // time(NULL) = 1259071266
288 // write(2, "ntpd: entering poll 15 secs\n", 28) = 28
289 // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
290 // recv(3, "yyy", 68, MSG_DONTWAIT) = 48
291 // ^^^ this recv will receive packets to any local port!
293 // Uncomment this and use strace to see it in action:
294 #define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); }
298 len_and_sockaddr *local_lsa;
300 //TODO: big ntpd uses all IPs, not just 1st, do we need to mimic that?
301 //TODO: periodically re-resolve DNS names?
303 p->lsa = host2sockaddr(p->hostname, 123);
305 set_next(p, INTERVAL_QUERY_PATHETIC);
308 p->dotted = xmalloc_sockaddr2dotted_noport(&p->lsa->u.sa);
311 family = p->lsa->u.sa.sa_family;
312 p->fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
313 /* local_lsa has "null" address and port 0 now.
314 * bind() ensures we have a *particular port* selected by kernel
315 * and remembered in p->fd, thus later recv(p->fd)
316 * receives only packets sent to this port.
319 xbind(fd, &local_lsa->u.sa, local_lsa->len);
321 #if ENABLE_FEATURE_IPV6
322 if (family == AF_INET)
324 setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
329 * Send out a random 64-bit number as our transmit time. The NTP
330 * server will copy said number into the originate field on the
331 * response that it sends us. This is totally legal per the SNTP spec.
333 * The impact of this is two fold: we no longer send out the current
334 * system time for the world to see (which may aid an attacker), and
335 * it gives us a (not very secure) way of knowing that we're not
336 * getting spoofed by an attacker that can't capture our traffic
337 * but can spoof packets from the NTP server we're communicating with.
339 * Save the real transmit timestamp locally.
342 p->msg.m_xmttime.int_partl = random();
343 p->msg.m_xmttime.fractionl = random();
344 p->xmttime = gettime1900d();
346 if (do_sendto(p->fd, /*from:*/ NULL, /*to:*/ &p->lsa->u.sa, /*addrlen:*/ p->lsa->len,
347 &p->msg, NTP_MSGSIZE_NOAUTH) == -1
351 set_next(p, INTERVAL_QUERY_PATHETIC);
356 bb_error_msg("sent query to %s", p->dotted);
357 set_next(p, QUERYTIME_MAX);
363 /* Time is stepped only once, when the first packet from a peer is received.
366 step_time_once(double offset)
373 if (G.time_is_stepped)
375 G.time_is_stepped = 1;
377 /* if the offset is small, don't step, slew (later) */
378 if (offset < STEPTIME_MIN_OFFSET && offset > -STEPTIME_MIN_OFFSET)
381 gettimeofday(&tv, NULL); /* never fails */
383 offset += 1.0e-6 * tv.tv_usec;
384 d_to_tv(offset, &tv);
386 if (settimeofday(&tv, NULL) == -1)
387 bb_perror_msg_and_die("settimeofday");
390 strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
392 bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
394 for (item = G.ntp_peers; item != NULL; item = item->link) {
395 ntp_peer_t *p = (ntp_peer_t *) item->data;
396 p->next_action_time -= offset;
400 if (option_mask32 & OPT_q)
405 /* Time is periodically slewed when we collect enough
409 compare_offsets(const void *aa, const void *bb)
411 const ntp_peer_t *const *a = aa;
412 const ntp_peer_t *const *b = bb;
413 if ((*a)->update.o_offset < (*b)->update.o_offset)
415 return ((*a)->update.o_offset > (*b)->update.o_offset);
418 updated_scale(double offset)
422 if (offset > QSCALE_OFF_MAX)
424 if (offset < QSCALE_OFF_MIN)
425 return QSCALE_OFF_MAX / QSCALE_OFF_MIN;
426 return QSCALE_OFF_MAX / offset;
432 double offset_median;
436 ntp_peer_t **peers = xzalloc(sizeof(peers[0]) * G.peer_cnt);
437 unsigned goodpeer_cnt = 0;
440 for (item = G.ntp_peers; item != NULL; item = item->link) {
441 ntp_peer_t *p = (ntp_peer_t *) item->data;
442 if (p->trustlevel < TRUSTLEVEL_BADPEER)
444 if (!p->update.o_good) {
448 peers[goodpeer_cnt++] = p;
451 if (goodpeer_cnt == 0) {
456 qsort(peers, goodpeer_cnt, sizeof(peers[0]), compare_offsets);
458 middle = goodpeer_cnt / 2;
459 if (middle != 0 && (goodpeer_cnt & 1) == 0) {
460 offset_median = (peers[middle-1]->update.o_offset + peers[middle]->update.o_offset) / 2;
461 G.rootdelay = (peers[middle-1]->update.o_delay + peers[middle]->update.o_delay) / 2;
462 G.stratum = 1 + MAX(peers[middle-1]->update.o_stratum, peers[middle]->update.o_stratum);
464 offset_median = peers[middle]->update.o_offset;
465 G.rootdelay = peers[middle]->update.o_delay;
466 G.stratum = 1 + peers[middle]->update.o_stratum;
468 G.leap = peers[middle]->update.o_leap;
469 G.refid4 = peers[middle]->update.o_refid4;
471 #if ENABLE_FEATURE_IPV6
472 peers[middle]->lsa->u.sa.sa_family != AF_INET ?
475 peers[middle]->lsa->u.sin.sin_addr.s_addr;
478 //TODO: if (offset_median > BIG) step_time(offset_median)?
480 G.scale = updated_scale(offset_median);
482 bb_error_msg("adjusting clock by %fs, our stratum is %u, time scale %u",
483 offset_median, G.stratum, G.scale);
486 d_to_tv(offset_median, &tv);
487 if (adjtime(&tv, &tv) == -1)
488 bb_perror_msg_and_die("adjtime failed");
490 bb_error_msg("old adjust: %d.%06u", (int)tv.tv_sec, (unsigned)tv.tv_usec);
492 if (G.first_adj_done) {
493 uint8_t synced = (tv.tv_sec == 0 && tv.tv_usec == 0);
494 if (synced != G.synced) {
496 bb_error_msg("clock is %ssynced", synced ? "" : "un");
499 G.first_adj_done = 1;
501 G.reftime = gettime1900d();
504 for (item = G.ntp_peers; item != NULL; item = item->link) {
505 ntp_peer_t *p = (ntp_peer_t *) item->data;
506 p->update.o_good = 0;
511 update_peer_data(ntp_peer_t *p)
514 * Find the offset which arrived with the lowest delay.
515 * Use that as the peer update.
516 * Invalidate it and all older ones.
522 for (i = 0; i < OFFSET_ARRAY_SIZE; i++) {
523 if (p->reply[i].o_good) {
525 if (best < 0 || p->reply[i].o_delay < p->reply[best].o_delay)
530 if (good < 8) //FIXME: was it meant to be OFFSET_ARRAY_SIZE, not 8?
533 memcpy(&p->update, &p->reply[best], sizeof(p->update));
536 for (i = 0; i < OFFSET_ARRAY_SIZE; i++)
537 if (p->reply[i].o_rcvd <= p->reply[best].o_rcvd)
538 p->reply[i].o_good = 0;
542 scale_interval(unsigned requested)
544 unsigned interval, r;
545 interval = requested * G.scale;
546 r = (unsigned)random() % (unsigned)(MAX(5, interval / 10));
547 return (interval + r);
550 recv_and_process_peer_pkt(ntp_peer_t *p)
554 double T1, T2, T3, T4;
556 ntp_offset_t *offset;
558 /* We can recvfrom here and check from.IP, but some multihomed
559 * ntp servers reply from their *other IP*.
560 * TODO: maybe we should check at least what we can: from.port == 123?
562 size = recv(p->fd, &msg, sizeof(msg), MSG_DONTWAIT);
564 bb_perror_msg("recv(%s) error", p->dotted);
565 if (errno == EHOSTUNREACH || errno == EHOSTDOWN
566 || errno == ENETUNREACH || errno == ENETDOWN
567 || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
570 //TODO: always do this?
571 set_next(p, error_interval());
577 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
578 bb_error_msg("malformed packet received from %s", p->dotted);
582 if (msg.m_orgtime.int_partl != p->msg.m_xmttime.int_partl
583 || msg.m_orgtime.fractionl != p->msg.m_xmttime.fractionl
588 if ((msg.m_status & LI_ALARM) == LI_ALARM
589 || msg.m_stratum == 0
590 || msg.m_stratum > NTP_MAXSTRATUM
592 interval = error_interval();
593 bb_error_msg("reply from %s: not synced, next query in %us", p->dotted, interval);
598 * From RFC 2030 (with a correction to the delay math):
600 * Timestamp Name ID When Generated
601 * ------------------------------------------------------------
602 * Originate Timestamp T1 time request sent by client
603 * Receive Timestamp T2 time request received by server
604 * Transmit Timestamp T3 time reply sent by server
605 * Destination Timestamp T4 time reply received by client
607 * The roundtrip delay d and local clock offset t are defined as
609 * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2.
614 T2 = lfp_to_d(msg.m_rectime);
615 T3 = lfp_to_d(msg.m_xmttime);
617 offset = &p->reply[p->shift];
619 offset->o_offset = ((T2 - T1) + (T3 - T4)) / 2;
620 offset->o_delay = (T4 - T1) - (T3 - T2);
621 if (offset->o_delay < 0) {
622 bb_error_msg("reply from %s: negative delay %f", p->dotted, offset->o_delay);
623 interval = error_interval();
624 set_next(p, interval);
627 //UNUSED: offset->o_error = (T2 - T1) - (T3 - T4);
628 offset->o_rcvd = time(NULL); /* can use (time_t)(T4 - OFFSET_1900_1970) too */
631 offset->o_leap = (msg.m_status & LI_MASK);
632 //UNUSED: offset->o_precision = msg.m_precision;
633 //UNUSED: offset->o_rootdelay = sfp_to_d(msg.m_rootdelay);
634 //UNUSED: offset->o_rootdispersion = sfp_to_d(msg.m_dispersion);
635 //UNUSED: offset->o_refid = ntohl(msg.m_refid);
636 offset->o_refid4 = msg.m_xmttime.fractionl;
637 //UNUSED: offset->o_reftime = lfp_to_d(msg.m_reftime);
638 //UNUSED: offset->o_poll = msg.m_ppoll;
639 offset->o_stratum = msg.m_stratum;
641 if (p->trustlevel < TRUSTLEVEL_PATHETIC)
642 interval = scale_interval(INTERVAL_QUERY_PATHETIC);
643 else if (p->trustlevel < TRUSTLEVEL_AGRESSIVE)
644 interval = scale_interval(INTERVAL_QUERY_AGRESSIVE);
646 interval = scale_interval(INTERVAL_QUERY_NORMAL);
648 set_next(p, interval);
650 /* every received reply which we do not discard increases trust */
651 if (p->trustlevel < TRUSTLEVEL_MAX) {
653 if (p->trustlevel == TRUSTLEVEL_BADPEER)
654 bb_error_msg("peer %s now valid", p->dotted);
658 bb_error_msg("reply from %s: offset %f delay %f, next query in %us", p->dotted,
659 offset->o_offset, offset->o_delay, interval);
662 //TODO: do it after all peers had a chance to return at least one reply?
663 step_time_once(offset->o_offset);
666 if (p->shift >= OFFSET_ARRAY_SIZE)
670 /* We do not expect any more packets from this peer for now.
671 * Closing the socket informs kernel about it.
672 * We open a new socket when we send a new query.
680 #if ENABLE_FEATURE_NTPD_SERVER
682 recv_and_process_client_pkt(void /*int fd*/)
687 len_and_sockaddr *to;
688 struct sockaddr *from;
690 uint8_t query_status;
692 l_fixedpt_t query_xmttime;
694 to = get_sock_lsa(G.listen_fd);
695 from = xzalloc(to->len);
697 size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
698 if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
703 bb_perror_msg_and_die("recv");
705 addr = xmalloc_sockaddr2dotted_noport(from);
706 bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
711 query_status = msg.m_status;
712 query_ppoll = msg.m_ppoll;
713 query_xmttime = msg.m_xmttime;
715 /* Build a reply packet */
716 memset(&msg, 0, sizeof(msg));
717 msg.m_status = G.synced ? G.leap : LI_ALARM;
718 msg.m_status |= (query_status & VERSION_MASK);
719 msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
720 MODE_SERVER : MODE_SYM_PAS;
721 msg.m_stratum = G.stratum;
722 msg.m_ppoll = query_ppoll;
723 msg.m_precision = G_precision;
724 rectime = gettime1900d();
725 msg.m_xmttime = msg.m_rectime = d_to_lfp(rectime);
726 msg.m_reftime = d_to_lfp(G.reftime);
727 //msg.m_xmttime = d_to_lfp(gettime1900d()); // = msg.m_rectime
728 msg.m_orgtime = query_xmttime;
729 msg.m_rootdelay = d_to_sfp(G.rootdelay);
730 version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
731 msg.m_refid = (version > (3 << VERSION_SHIFT)) ? G.refid4 : G.refid;
733 /* We reply from the local address packet was sent to,
734 * this makes to/from look swapped here: */
735 do_sendto(G.listen_fd,
736 /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
745 /* Upstream ntpd's options:
747 * -4 Force DNS resolution of host names to the IPv4 namespace.
748 * -6 Force DNS resolution of host names to the IPv6 namespace.
749 * -a Require cryptographic authentication for broadcast client,
750 * multicast client and symmetric passive associations.
751 * This is the default.
752 * -A Do not require cryptographic authentication for broadcast client,
753 * multicast client and symmetric passive associations.
754 * This is almost never a good idea.
755 * -b Enable the client to synchronize to broadcast servers.
757 * Specify the name and path of the configuration file,
758 * default /etc/ntp.conf
759 * -d Specify debugging mode. This option may occur more than once,
760 * with each occurrence indicating greater detail of display.
762 * Specify debugging level directly.
764 * Specify the name and path of the frequency file.
765 * This is the same operation as the "driftfile FILE"
766 * configuration command.
767 * -g Normally, ntpd exits with a message to the system log
768 * if the offset exceeds the panic threshold, which is 1000 s
769 * by default. This option allows the time to be set to any value
770 * without restriction; however, this can happen only once.
771 * If the threshold is exceeded after that, ntpd will exit
772 * with a message to the system log. This option can be used
773 * with the -q and -x options. See the tinker command for other options.
775 * Chroot the server to the directory jaildir. This option also implies
776 * that the server attempts to drop root privileges at startup
777 * (otherwise, chroot gives very little additional security).
778 * You may need to also specify a -u option.
780 * Specify the name and path of the symmetric key file,
781 * default /etc/ntp/keys. This is the same operation
782 * as the "keys FILE" configuration command.
784 * Specify the name and path of the log file. The default
785 * is the system log file. This is the same operation as
786 * the "logfile FILE" configuration command.
787 * -L Do not listen to virtual IPs. The default is to listen.
789 * -N To the extent permitted by the operating system,
790 * run the ntpd at the highest priority.
792 * Specify the name and path of the file used to record the ntpd
793 * process ID. This is the same operation as the "pidfile FILE"
794 * configuration command.
796 * To the extent permitted by the operating system,
797 * run the ntpd at the specified priority.
798 * -q Exit the ntpd just after the first time the clock is set.
799 * This behavior mimics that of the ntpdate program, which is
800 * to be retired. The -g and -x options can be used with this option.
801 * Note: The kernel time discipline is disabled with this option.
803 * Specify the default propagation delay from the broadcast/multicast
804 * server to this client. This is necessary only if the delay
805 * cannot be computed automatically by the protocol.
807 * Specify the directory path for files created by the statistics
808 * facility. This is the same operation as the "statsdir DIR"
809 * configuration command.
811 * Add a key number to the trusted key list. This option can occur
814 * Specify a user, and optionally a group, to switch to.
817 * Add a system variable listed by default.
818 * -x Normally, the time is slewed if the offset is less than the step
819 * threshold, which is 128 ms by default, and stepped if above
820 * the threshold. This option sets the threshold to 600 s, which is
821 * well within the accuracy window to set the clock manually.
822 * Note: since the slew rate of typical Unix kernels is limited
823 * to 0.5 ms/s, each second of adjustment requires an amortization
824 * interval of 2000 s. Thus, an adjustment as much as 600 s
825 * will take almost 14 days to complete. This option can be used
826 * with the -g and -q options. See the tinker command for other options.
827 * Note: The kernel time discipline is disabled with this option.
830 /* By doing init in a separate function we decrease stack usage
833 static NOINLINE void ntp_init(char **argv)
841 bb_error_msg_and_die(bb_msg_you_must_be_root);
844 opt_complementary = "dd:p::"; /* d: counter, p: list */
845 opts = getopt32(argv,
847 "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
849 "46aAbgL", /* compat, ignored */
851 if (!(opts & (OPT_p|OPT_l)))
853 if (opts & OPT_x) /* disable stepping, only slew is allowed */
854 G.time_is_stepped = 1;
856 add_peers(llist_pop(&peers));
857 if (!(opts & OPT_n)) {
858 bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
859 logmode = LOGMODE_NONE;
861 #if ENABLE_FEATURE_NTPD_SERVER
864 G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
865 socket_want_pktinfo(G.listen_fd);
866 setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
869 /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
871 setpriority(PRIO_PROCESS, 0, -15);
873 /* Set some globals */
875 /* With constant b = 100, G.precision is also constant -6.
876 * Uncomment this and you'll see */
882 /* We can use sys_clock_getres but assuming 10ms tick should be fine */
883 clock_getres(CLOCK_REALTIME, &tp);
885 tp.tv_nsec = 10000000;
886 b = 1000000000 / tp.tv_nsec; /* convert to Hz */
888 b = 100; /* b = 1000000000/10000000 = 100 */
892 //G.precision = prec;
893 bb_error_msg("G.precision:%d", prec); /* -6 */
898 bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo);
899 bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN);
902 int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
903 int ntpd_main(int argc UNUSED_PARAM, char **argv)
907 ntp_peer_t **idx2peer;
909 memset(&g, 0, sizeof(g));
910 SET_PTR_TO_GLOBALS(&g);
915 unsigned cnt = g.peer_cnt;
916 /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
917 idx2peer = xzalloc(sizeof(void *) * (cnt + ENABLE_FEATURE_NTPD_SERVER));
918 pfd = xzalloc(sizeof(pfd[0]) * (cnt + ENABLE_FEATURE_NTPD_SERVER));
921 while (!bb_got_signal) {
924 unsigned sent_cnt, trial_cnt;
926 time_t cur_time, nextaction;
928 /* Nothing between here and poll() blocks for any significant time */
930 cur_time = time(NULL);
931 nextaction = cur_time + 3600;
934 #if ENABLE_FEATURE_NTPD_SERVER
935 if (g.listen_fd != -1) {
936 pfd[0].fd = g.listen_fd;
937 pfd[0].events = POLLIN;
941 /* Pass over peer list, send requests, time out on receives */
942 sent_cnt = trial_cnt = 0;
943 for (item = g.ntp_peers; item != NULL; item = item->link) {
944 ntp_peer_t *p = (ntp_peer_t *) item->data;
946 /* Overflow-safe "if (p->next_action_time <= cur_time) ..." */
947 if ((int)(cur_time - p->next_action_time) >= 0) {
949 /* Time to send new req */
951 if (send_query_to_peer(p) == 0)
954 /* Timed out waiting for reply */
957 timeout = error_interval();
958 bb_error_msg("timed out waiting for %s, "
959 "next query in %us", p->dotted, timeout);
960 if (p->trustlevel >= TRUSTLEVEL_BADPEER) {
962 if (p->trustlevel < TRUSTLEVEL_BADPEER)
963 bb_error_msg("peer %s now invalid", p->dotted);
965 set_next(p, timeout);
969 if (p->next_action_time < nextaction)
970 nextaction = p->next_action_time;
973 /* Wait for reply from this peer */
975 pfd[i].events = POLLIN;
981 if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0)
982 step_time_once(0); /* no good peers, don't wait */
984 timeout = nextaction - cur_time;
988 /* Here we may block */
990 bb_error_msg("poll %us, sockets:%u", timeout, i);
991 nfds = poll(pfd, i, timeout * 1000);
995 /* Process any received packets */
997 #if ENABLE_FEATURE_NTPD_SERVER
998 if (g.listen_fd != -1) {
999 if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
1001 recv_and_process_client_pkt(/*g.listen_fd*/);
1006 for (; nfds != 0 && j < i; j++) {
1007 if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
1009 recv_and_process_peer_pkt(idx2peer[j]);
1012 } /* while (!bb_got_signal) */
1014 kill_myself_with_sig(bb_got_signal);