--- /dev/null
+/*
+ * NTP client/server, based on OpenNTPD 3.9p1
+ *
+ * Author: Adam Tkac <vonsch@gmail.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ *
+ * Parts of OpenNTPD clock syncronization code is replaced by
+ * code which is based on ntp-4.2.6. It carries the following
+ * copyright notice:
+ *
+ ***********************************************************************
+ * *
+ * Copyright (c) University of Delaware 1992-2009 *
+ * *
+ * Permission to use, copy, modify, and distribute this software and *
+ * its documentation for any purpose with or without fee is hereby *
+ * granted, provided that the above copyright notice appears in all *
+ * copies and that both the copyright notice and this permission *
+ * notice appear in supporting documentation, and that the name *
+ * University of Delaware not be used in advertising or publicity *
+ * pertaining to distribution of the software without specific, *
+ * written prior permission. The University of Delaware makes no *
+ * representations about the suitability this software for any *
+ * purpose. It is provided "as is" without express or implied *
+ * warranty. *
+ * *
+ ***********************************************************************
+ */
+#include "libbb.h"
+#include <math.h>
+#include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
+#include <sys/timex.h>
+#ifndef IPTOS_LOWDELAY
+# define IPTOS_LOWDELAY 0x10
+#endif
+#ifndef IP_PKTINFO
+# error "Sorry, your kernel has to support IP_PKTINFO"
+#endif
+
+
+#define RETRY_INTERVAL 5 /* on error, retry in N secs */
+#define QUERYTIME_MAX 15 /* wait for reply up to N secs */
+
+#define FREQ_TOLERANCE 15e-6 /* % frequency tolerance (15 PPM) */
+#define MINPOLL 4 /* % minimum poll interval (6: 64 s) */
+#define MAXPOLL 12 /* % maximum poll interval (12: 1.1h, 17: 36.4h) (was 17) */
+#define MINDISP 0.01 /* % minimum dispersion (s) */
+#define MAXDISP 16 /* maximum dispersion (s) */
+#define MAXSTRAT 16 /* maximum stratum (infinity metric) */
+#define MAXDIST 1 /* % distance threshold (s) */
+#define MIN_SELECTED 1 /* % minimum intersection survivors */
+#define MIN_CLUSTERED 3 /* % minimum cluster survivors */
+
+#define MAXFREQ 0.000500 /* frequency tolerance (500 PPM) */
+
+/* Clock discipline parameters and constants */
+#define STEP_THRESHOLD 0.128 /* step threshold (s) */
+#define WATCH_THRESHOLD 150 /* stepout threshold (s). std ntpd uses 900 (11 mins (!)) */
+/* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */
+#define PANIC_THRESHOLD 1000 /* panic threshold (s) */
+
+/* Poll-adjust threshold.
+ * When we see that offset is small enough compared to discipline jitter,
+ * we grow a counter: += poll_ext. When it goes over POLLADJ_LIMIT,
+ * we poll_ext++. If offset isn't small, counter -= poll_ext*2,
+ * and when it goes below -POLLADJ_LIMIT, we poll_ext--
+ */
+#define POLLADJ_LIMIT 30
+/* If offset < POLLADJ_GATE * discipline_jitter, then we can increase
+ * poll interval (we think we can't improve timekeeping
+ * by staying at smaller poll).
+ */
+#define POLLADJ_GATE 4
+/* Compromise Allan intercept (s). doc uses 1500, std ntpd uses 512 */
+#define ALLAN 512
+/* PLL loop gain */
+#define PLL 65536
+/* FLL loop gain [why it depends on MAXPOLL??] */
+#define FLL (MAXPOLL + 1)
+/* Parameter averaging constant */
+#define AVG 4
+
+/* Verbosity control (max level of -dddd options accepted).
+ * max 5 is very talkative (and bloated). 2 is non-bloated,
+ * production level setting.
+ */
+#define MAX_VERBOSE 2
+
+#define VERB1 if (MAX_VERBOSE && G.verbose)
+#define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
+#define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
+#define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
+#define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
+
+
+enum {
+ NTP_VERSION = 4,
+ NTP_MAXSTRATUM = 15,
+
+ NTP_DIGESTSIZE = 16,
+ NTP_MSGSIZE_NOAUTH = 48,
+ NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
+
+ /* Status Masks */
+ MODE_MASK = (7 << 0),
+ VERSION_MASK = (7 << 3),
+ VERSION_SHIFT = 3,
+ LI_MASK = (3 << 6),
+
+ /* Leap Second Codes (high order two bits of m_status) */
+ LI_NOWARNING = (0 << 6), /* no warning */
+ LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
+ LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
+ LI_ALARM = (3 << 6), /* alarm condition */
+
+ /* Mode values */
+ MODE_RES0 = 0, /* reserved */
+ MODE_SYM_ACT = 1, /* symmetric active */
+ MODE_SYM_PAS = 2, /* symmetric passive */
+ MODE_CLIENT = 3, /* client */
+ MODE_SERVER = 4, /* server */
+ MODE_BROADCAST = 5, /* broadcast */
+ MODE_RES1 = 6, /* reserved for NTP control message */
+ MODE_RES2 = 7, /* reserved for private use */
+};
+
+//TODO: better base selection
+#define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
+
+#define NUM_DATAPOINTS 8
+
+typedef struct {
+ uint32_t int_partl;
+ uint32_t fractionl;
+} l_fixedpt_t;
+
+typedef struct {
+ uint16_t int_parts;
+ uint16_t fractions;
+} s_fixedpt_t;
+
+typedef struct {
+ uint8_t m_status; /* status of local clock and leap info */
+ uint8_t m_stratum;
+ uint8_t m_ppoll; /* poll value */
+ int8_t m_precision_exp;
+ s_fixedpt_t m_rootdelay;
+ s_fixedpt_t m_rootdisp;
+ uint32_t m_refid;
+ l_fixedpt_t m_reftime;
+ l_fixedpt_t m_orgtime;
+ l_fixedpt_t m_rectime;
+ l_fixedpt_t m_xmttime;
+ uint32_t m_keyid;
+ uint8_t m_digest[NTP_DIGESTSIZE];
+} msg_t;
+
+typedef struct {
+ double d_recv_time;
+ double d_offset;
+ double d_dispersion;
+} datapoint_t;
+
+typedef struct {
+ len_and_sockaddr *p_lsa;
+ char *p_dotted;
+ /* when to send new query (if p_fd == -1)
+ * or when receive times out (if p_fd >= 0): */
+ time_t next_action_time;
+ int p_fd;
+ int datapoint_idx;
+ uint32_t lastpkt_refid;
+ uint8_t lastpkt_leap;
+ uint8_t lastpkt_stratum;
+ uint8_t p_reachable_bits;
+ double p_xmttime;
+ double lastpkt_recv_time;
+ double lastpkt_delay;
+ double lastpkt_rootdelay;
+ double lastpkt_rootdisp;
+ /* produced by filter algorithm: */
+ double filter_offset;
+ double filter_dispersion;
+ double filter_jitter;
+ datapoint_t filter_datapoint[NUM_DATAPOINTS];
+ /* last sent packet: */
+ msg_t p_xmt_msg;
+} peer_t;
+
+
+enum {
+ OPT_n = (1 << 0),
+ OPT_q = (1 << 1),
+ OPT_N = (1 << 2),
+ OPT_x = (1 << 3),
+ /* Insert new options above this line. */
+ /* Non-compat options: */
+ OPT_p = (1 << 4),
+ OPT_l = (1 << 5) * ENABLE_FEATURE_NTPD_SERVER,
+};
+
+struct globals {
+ /* total round trip delay to currently selected reference clock */
+ double rootdelay;
+ /* reference timestamp: time when the system clock was last set or corrected */
+ double reftime;
+ /* total dispersion to currently selected reference clock */
+ double rootdisp;
+ llist_t *ntp_peers;
+#if ENABLE_FEATURE_NTPD_SERVER
+ int listen_fd;
+#endif
+ unsigned verbose;
+ unsigned peer_cnt;
+ /* refid: 32-bit code identifying the particular server or reference clock
+ * in stratum 0 packets this is a four-character ASCII string,
+ * called the kiss code, used for debugging and monitoring
+ * in stratum 1 packets this is a four-character ASCII string
+ * assigned to the reference clock by IANA. Example: "GPS "
+ * in stratum 2+ packets, it's IPv4 address or 4 first bytes of MD5 hash of IPv6
+ */
+ uint32_t refid;
+ uint8_t leap;
+ /* precision is defined as the larger of the resolution and time to
+ * read the clock, in log2 units. For instance, the precision of a
+ * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
+ * system clock hardware representation is to the nanosecond.
+ *
+ * Delays, jitters of various kinds are clamper down to precision.
+ *
+ * If precision_sec is too large, discipline_jitter gets clamped to it
+ * and if offset is much smaller than discipline_jitter, poll interval
+ * grows even though we really can benefit from staying at smaller one,
+ * collecting non-lagged datapoits and correcting the offset.
+ * (Lagged datapoits exist when poll_exp is large but we still have
+ * systematic offset error - the time distance between datapoints
+ * is significat and older datapoints have smaller offsets.
+ * This makes our offset estimation a bit smaller than reality)
+ * Due to this effect, setting G_precision_sec close to
+ * STEP_THRESHOLD isn't such a good idea - offsets may grow
+ * too big and we will step. I observed it with -6.
+ *
+ * OTOH, setting precision too small would result in futile attempts
+ * to syncronize to the unachievable precision.
+ *
+ * -6 is 1/64 sec, -7 is 1/128 sec and so on.
+ */
+#define G_precision_exp -8
+#define G_precision_sec (1.0 / (1 << (- G_precision_exp)))
+ uint8_t stratum;
+ /* Bool. After set to 1, never goes back to 0: */
+//TODO: fix logic:
+// uint8_t time_was_stepped;
+ uint8_t adjtimex_was_done;
+
+ uint8_t discipline_state; // doc calls it c.state
+ uint8_t poll_exp; // s.poll
+ int polladj_count; // c.count
+ double discipline_jitter; // c.jitter
+ double last_update_offset; // c.last
+ double discipline_freq_drift; // c.freq
+//TODO: conditionally calculate wander? it's used only for logging
+ double discipline_wander; // c.wander
+ double last_update_recv_time; // s.t
+//TODO: add s.jitter - grep for it here and see clock_combine() in doc
+};
+#define G (*ptr_to_globals)
+
+static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
+
+
+static double LOG2D(int a)
+{
+ if (a < 0)
+ return 1.0 / (1UL << -a);
+ return 1UL << a;
+}
+static ALWAYS_INLINE double SQUARE(double x)
+{
+ return x * x;
+}
+static ALWAYS_INLINE double MAXD(double a, double b)
+{
+ if (a > b)
+ return a;
+ return b;
+}
+static ALWAYS_INLINE double MIND(double a, double b)
+{
+ if (a < b)
+ return a;
+ return b;
+}
+#define SQRT(x) (sqrt(x))
+
+static double
+gettime1900d(void)
+{
+ struct timeval tv;
+ gettimeofday(&tv, NULL); /* never fails */
+ return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970);
+}
+
+static void
+d_to_tv(double d, struct timeval *tv)
+{
+ tv->tv_sec = (long)d;
+ tv->tv_usec = (d - tv->tv_sec) * 1000000;
+}
+
+static double
+lfp_to_d(l_fixedpt_t lfp)
+{
+ double ret;
+ lfp.int_partl = ntohl(lfp.int_partl);
+ lfp.fractionl = ntohl(lfp.fractionl);
+ ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
+ return ret;
+}
+static double
+sfp_to_d(s_fixedpt_t sfp)
+{
+ double ret;
+ sfp.int_parts = ntohs(sfp.int_parts);
+ sfp.fractions = ntohs(sfp.fractions);
+ ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
+ return ret;
+}
+#if ENABLE_FEATURE_NTPD_SERVER
+static l_fixedpt_t
+d_to_lfp(double d)
+{
+ l_fixedpt_t lfp;
+ lfp.int_partl = (uint32_t)d;
+ lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
+ lfp.int_partl = htonl(lfp.int_partl);
+ lfp.fractionl = htonl(lfp.fractionl);
+ return lfp;
+}
+static s_fixedpt_t
+d_to_sfp(double d)
+{
+ s_fixedpt_t sfp;
+ sfp.int_parts = (uint16_t)d;
+ sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
+ sfp.int_parts = htons(sfp.int_parts);
+ sfp.fractions = htons(sfp.fractions);
+ return sfp;
+}
+#endif
+
+static double
+dispersion(const datapoint_t *dp, double t)
+{
+ return dp->d_dispersion + FREQ_TOLERANCE * (t - dp->d_recv_time);
+}
+
+static double
+root_distance(peer_t *p, double t)
+{
+ /* The root synchronization distance is the maximum error due to
+ * all causes of the local clock relative to the primary server.
+ * It is defined as half the total delay plus total dispersion
+ * plus peer jitter.
+ */
+ return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2
+ + p->lastpkt_rootdisp
+ + p->filter_dispersion
+ + FREQ_TOLERANCE * (t - p->lastpkt_recv_time)
+ + p->filter_jitter;
+}
+
+static void
+set_next(peer_t *p, unsigned t)
+{
+ p->next_action_time = time(NULL) + t;
+}
+
+/*
+ * Peer clock filter and its helpers
+ */
+static void
+filter_datapoints(peer_t *p, double t)
+{
+ int i, idx;
+ double minoff, maxoff, wavg, sum, w;
+ double x = x;
+
+ minoff = maxoff = p->filter_datapoint[0].d_offset;
+ for (i = 1; i < NUM_DATAPOINTS; i++) {
+ if (minoff > p->filter_datapoint[i].d_offset)
+ minoff = p->filter_datapoint[i].d_offset;
+ if (maxoff < p->filter_datapoint[i].d_offset)
+ maxoff = p->filter_datapoint[i].d_offset;
+ }
+
+ idx = p->datapoint_idx; /* most recent datapoint */
+ /* Average offset:
+ * Drop two outliers and take weighted average of the rest:
+ * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
+ * we use older6/32, not older6/64 since sum of weights should be 1:
+ * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
+ */
+ wavg = 0;
+ w = 0.5;
+ // n-1
+ // --- dispersion(i)
+ // filter_dispersion = \ -------------
+ // / (i+1)
+ // --- 2
+ // i=0
+ sum = 0;
+ for (i = 0; i < NUM_DATAPOINTS; i++) {
+ VERB4 {
+ bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
+ i,
+ p->filter_datapoint[idx].d_offset,
+ p->filter_datapoint[idx].d_dispersion, dispersion(&p->filter_datapoint[idx], t),
+ t - p->filter_datapoint[idx].d_recv_time,
+ (minoff == p->filter_datapoint[idx].d_offset || maxoff == p->filter_datapoint[idx].d_offset)
+ ? " (outlier by offset)" : ""
+ );
+ }
+
+ sum += dispersion(&p->filter_datapoint[idx], t) / (2 << i);
+
+ if (minoff == p->filter_datapoint[idx].d_offset) {
+ minoff -= 1;
+ } else
+ if (maxoff == p->filter_datapoint[idx].d_offset) {
+ maxoff += 1;
+ } else {
+ x = p->filter_datapoint[idx].d_offset * w;
+ wavg += x;
+ w /= 2;
+ }
+
+ idx = (idx - 1) & (NUM_DATAPOINTS - 1);
+ }
+ wavg += x; /* add another older6/64 to form older6/32 */
+ p->filter_offset = wavg;
+ p->filter_dispersion = sum;
+
+ // +----- -----+ ^ 1/2
+ // | n-1 |
+ // | --- |
+ // 1 | \ 2 |
+ // filter_jitter = --- * | / (avg-offset_j) |
+ // n | --- |
+ // | j=0 |
+ // +----- -----+
+ // where n is the number of valid datapoints in the filter (n > 1);
+ // if filter_jitter < precision then filter_jitter = precision
+ sum = 0;
+ for (i = 0; i < NUM_DATAPOINTS; i++) {
+ sum += SQUARE(wavg - p->filter_datapoint[i].d_offset);
+ }
+ sum = SQRT(sum) / NUM_DATAPOINTS;
+ p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
+
+ VERB3 bb_error_msg("filter offset:%f disp:%f jitter:%f",
+ p->filter_offset, p->filter_dispersion, p->filter_jitter);
+
+}
+
+static void
+reset_peer_stats(peer_t *p, double t, double offset)
+{
+ int i;
+ for (i = 0; i < NUM_DATAPOINTS; i++) {
+ if (offset < 16 * STEP_THRESHOLD) {
+ p->filter_datapoint[i].d_recv_time -= offset;
+ if (p->filter_datapoint[i].d_offset != 0) {
+ p->filter_datapoint[i].d_offset -= offset;
+ }
+ } else {
+ p->filter_datapoint[i].d_recv_time = t;
+ p->filter_datapoint[i].d_offset = 0;
+ p->filter_datapoint[i].d_dispersion = MAXDISP;
+ }
+ }
+ if (offset < 16 * STEP_THRESHOLD) {
+ p->lastpkt_recv_time -= offset;
+ } else {
+ p->p_reachable_bits = 0;
+ p->lastpkt_recv_time = t;
+ }
+ filter_datapoints(p, t); /* recalc p->filter_xxx */
+ p->next_action_time -= (time_t)offset;
+ VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
+}
+
+static void
+add_peers(char *s)
+{
+ peer_t *p;
+
+ p = xzalloc(sizeof(*p));
+ p->p_lsa = xhost2sockaddr(s, 123);
+ p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
+ p->p_fd = -1;
+ p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
+ p->next_action_time = time(NULL); /* = set_next(p, 0); */
+ reset_peer_stats(p, gettime1900d(), 16 * STEP_THRESHOLD);
+ /* Speed up initial sync: with small offsets from peers,
+ * 3 samples will sync
+ */
+ p->filter_datapoint[6].d_dispersion = 0;
+ p->filter_datapoint[7].d_dispersion = 0;
+
+ llist_add_to(&G.ntp_peers, p);
+ G.peer_cnt++;
+}
+
+static int
+do_sendto(int fd,
+ const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
+ msg_t *msg, ssize_t len)
+{
+ ssize_t ret;
+
+ errno = 0;
+ if (!from) {
+ ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
+ } else {
+ ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
+ }
+ if (ret != len) {
+ bb_perror_msg("send failed");
+ return -1;
+ }
+ return 0;
+}
+
+static int
+send_query_to_peer(peer_t *p)
+{
+ // Why do we need to bind()?
+ // See what happens when we don't bind:
+ //
+ // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
+ // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
+ // gettimeofday({1259071266, 327885}, NULL) = 0
+ // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
+ // ^^^ we sent it from some source port picked by kernel.
+ // time(NULL) = 1259071266
+ // write(2, "ntpd: entering poll 15 secs\n", 28) = 28
+ // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
+ // recv(3, "yyy", 68, MSG_DONTWAIT) = 48
+ // ^^^ this recv will receive packets to any local port!
+ //
+ // Uncomment this and use strace to see it in action:
+#define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); }
+
+ if (p->p_fd == -1) {
+ int fd, family;
+ len_and_sockaddr *local_lsa;
+
+ family = p->p_lsa->u.sa.sa_family;
+ p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
+ /* local_lsa has "null" address and port 0 now.
+ * bind() ensures we have a *particular port* selected by kernel
+ * and remembered in p->p_fd, thus later recv(p->p_fd)
+ * receives only packets sent to this port.
+ */
+ PROBE_LOCAL_ADDR
+ xbind(fd, &local_lsa->u.sa, local_lsa->len);
+ PROBE_LOCAL_ADDR
+#if ENABLE_FEATURE_IPV6
+ if (family == AF_INET)
+#endif
+ setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
+ free(local_lsa);
+ }
+
+ /*
+ * Send out a random 64-bit number as our transmit time. The NTP
+ * server will copy said number into the originate field on the
+ * response that it sends us. This is totally legal per the SNTP spec.
+ *
+ * The impact of this is two fold: we no longer send out the current
+ * system time for the world to see (which may aid an attacker), and
+ * it gives us a (not very secure) way of knowing that we're not
+ * getting spoofed by an attacker that can't capture our traffic
+ * but can spoof packets from the NTP server we're communicating with.
+ *
+ * Save the real transmit timestamp locally.
+ */
+ p->p_xmt_msg.m_xmttime.int_partl = random();
+ p->p_xmt_msg.m_xmttime.fractionl = random();
+ p->p_xmttime = gettime1900d();
+
+ if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
+ &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
+ ) {
+ close(p->p_fd);
+ p->p_fd = -1;
+ set_next(p, RETRY_INTERVAL);
+ return -1;
+ }
+
+ p->p_reachable_bits <<= 1;
+ VERB1 bb_error_msg("sent query to %s", p->p_dotted);
+ set_next(p, QUERYTIME_MAX);
+
+ return 0;
+}
+
+
+static void
+step_time(double offset)
+{
+ double dtime;
+ struct timeval tv;
+ char buf[80];
+ time_t tval;
+
+ gettimeofday(&tv, NULL); /* never fails */
+ dtime = offset + tv.tv_sec;
+ dtime += 1.0e-6 * tv.tv_usec;
+ d_to_tv(dtime, &tv);
+
+ if (settimeofday(&tv, NULL) == -1)
+ bb_perror_msg_and_die("settimeofday");
+
+ tval = tv.tv_sec;
+ strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
+
+ bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
+
+// G.time_was_stepped = 1;
+}
+
+
+/*
+ * Selection and clustering, and their helpers
+ */
+typedef struct {
+ peer_t *p;
+ int type;
+ double edge;
+} point_t;
+static int
+compare_point_edge(const void *aa, const void *bb)
+{
+ const point_t *a = aa;
+ const point_t *b = bb;
+ if (a->edge < b->edge) {
+ return -1;
+ }
+ return (a->edge > b->edge);
+}
+typedef struct {
+ peer_t *p;
+ double metric;
+} survivor_t;
+static int
+compare_survivor_metric(const void *aa, const void *bb)
+{
+ const survivor_t *a = aa;
+ const survivor_t *b = bb;
+ if (a->metric < b->metric)
+ return -1;
+ return (a->metric > b->metric);
+}
+static int
+fit(peer_t *p, double rd)
+{
+ if (p->p_reachable_bits == 0) {
+ VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
+ return 0;
+ }
+//TODO: we never accept such packets anyway, right?
+ if ((p->lastpkt_leap & LI_ALARM) == LI_ALARM
+ || p->lastpkt_stratum >= MAXSTRAT
+ ) {
+ VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
+ return 0;
+ }
+ /* rd is root_distance(p, t) */
+ if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
+ VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
+ return 0;
+ }
+//TODO
+// /* Do we have a loop? */
+// if (p->refid == p->dstaddr || p->refid == s.refid)
+// return 0;
+ return 1;
+}
+static peer_t*
+select_and_cluster(double t)
+{
+ llist_t *item;
+ int i, j;
+ int size = 3 * G.peer_cnt;
+ /* for selection algorithm */
+ point_t point[size];
+ unsigned num_points, num_candidates;
+ double low, high;
+ unsigned num_falsetickers;
+ /* for cluster algorithm */
+ survivor_t survivor[size];
+ unsigned num_survivors;
+
+ /* Selection */
+
+ num_points = 0;
+ item = G.ntp_peers;
+ while (item != NULL) {
+ peer_t *p = (peer_t *) item->data;
+ double rd = root_distance(p, t);
+ double offset = p->filter_offset;
+
+ if (!fit(p, rd)) {
+ item = item->link;
+ continue;
+ }
+
+ VERB4 bb_error_msg("interval: [%f %f %f] %s",
+ offset - rd,
+ offset,
+ offset + rd,
+ p->p_dotted
+ );
+ point[num_points].p = p;
+ point[num_points].type = -1;
+ point[num_points].edge = offset - rd;
+ num_points++;
+ point[num_points].p = p;
+ point[num_points].type = 0;
+ point[num_points].edge = offset;
+ num_points++;
+ point[num_points].p = p;
+ point[num_points].type = 1;
+ point[num_points].edge = offset + rd;
+ num_points++;
+ item = item->link;
+ }
+ num_candidates = num_points / 3;
+ if (num_candidates == 0) {
+ VERB3 bb_error_msg("no valid datapoints, no peer selected");
+ return NULL; /* never happers? */
+ }
+//TODO: sorting does not seem to be done in reference code
+ qsort(point, num_points, sizeof(point[0]), compare_point_edge);
+
+ /* Start with the assumption that there are no falsetickers.
+ * Attempt to find a nonempty intersection interval containing
+ * the midpoints of all truechimers.
+ * If a nonempty interval cannot be found, increase the number
+ * of assumed falsetickers by one and try again.
+ * If a nonempty interval is found and the number of falsetickers
+ * is less than the number of truechimers, a majority has been found
+ * and the midpoint of each truechimer represents
+ * the candidates available to the cluster algorithm.
+ */
+ num_falsetickers = 0;
+ while (1) {
+ int c;
+ unsigned num_midpoints = 0;
+
+ low = 1 << 9;
+ high = - (1 << 9);
+ c = 0;
+ for (i = 0; i < num_points; i++) {
+ /* We want to do:
+ * if (point[i].type == -1) c++;
+ * if (point[i].type == 1) c--;
+ * and it's simpler to do it this way:
+ */
+ c -= point[i].type;
+ if (c >= num_candidates - num_falsetickers) {
+ /* If it was c++ and it got big enough... */
+ low = point[i].edge;
+ break;
+ }
+ if (point[i].type == 0)
+ num_midpoints++;
+ }
+ c = 0;
+ for (i = num_points-1; i >= 0; i--) {
+ c += point[i].type;
+ if (c >= num_candidates - num_falsetickers) {
+ high = point[i].edge;
+ break;
+ }
+ if (point[i].type == 0)
+ num_midpoints++;
+ }
+ /* If the number of midpoints is greater than the number
+ * of allowed falsetickers, the intersection contains at
+ * least one truechimer with no midpoint - bad.
+ * Also, interval should be nonempty.
+ */
+ if (num_midpoints <= num_falsetickers && low < high)
+ break;
+ num_falsetickers++;
+ if (num_falsetickers * 2 >= num_candidates) {
+ VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected",
+ num_falsetickers, num_candidates);
+ return NULL;
+ }
+ }
+ VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
+ low, high, num_candidates, num_falsetickers);
+
+ /* Clustering */
+
+ /* Construct a list of survivors (p, metric)
+ * from the chime list, where metric is dominated
+ * first by stratum and then by root distance.
+ * All other things being equal, this is the order of preference.
+ */
+ num_survivors = 0;
+ for (i = 0; i < num_points; i++) {
+ peer_t *p;
+
+ if (point[i].edge < low || point[i].edge > high)
+ continue;
+ p = point[i].p;
+ survivor[num_survivors].p = p;
+//TODO: save root_distance in point_t and reuse here?
+ survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + root_distance(p, t);
+ VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s",
+ num_survivors, survivor[num_survivors].metric, p->p_dotted);
+ num_survivors++;
+ }
+ /* There must be at least MIN_SELECTED survivors to satisfy the
+ * correctness assertions. Ordinarily, the Byzantine criteria
+ * require four survivors, but for the demonstration here, one
+ * is acceptable.
+ */
+ if (num_survivors < MIN_SELECTED) {
+ VERB3 bb_error_msg("num_survivors %d < %d, no peer selected",
+ num_survivors, MIN_SELECTED);
+ return NULL;
+ }
+
+//looks like this is ONLY used by the fact that later we pick survivor[0].
+//we can avoid sorting then, just find the minimum once!
+ qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric);
+
+ /* For each association p in turn, calculate the selection
+ * jitter p->sjitter as the square root of the sum of squares
+ * (p->offset - q->offset) over all q associations. The idea is
+ * to repeatedly discard the survivor with maximum selection
+ * jitter until a termination condition is met.
+ */
+ while (1) {
+ unsigned max_idx = max_idx;
+ double max_selection_jitter = max_selection_jitter;
+ double min_jitter = min_jitter;
+
+ if (num_survivors <= MIN_CLUSTERED) {
+ bb_error_msg("num_survivors %d <= %d, not discarding more",
+ num_survivors, MIN_CLUSTERED);
+ break;
+ }
+
+ /* To make sure a few survivors are left
+ * for the clustering algorithm to chew on,
+ * we stop if the number of survivors
+ * is less than or equal to MIN_CLUSTERED (3).
+ */
+ for (i = 0; i < num_survivors; i++) {
+ double selection_jitter_sq;
+ peer_t *p = survivor[i].p;
+
+ if (i == 0 || p->filter_jitter < min_jitter)
+ min_jitter = p->filter_jitter;
+
+ selection_jitter_sq = 0;
+ for (j = 0; j < num_survivors; j++) {
+ peer_t *q = survivor[j].p;
+//TODO: where is 1/(n-1) * ... multiplier?
+ selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
+ }
+ if (i == 0 || selection_jitter_sq > max_selection_jitter) {
+ max_selection_jitter = selection_jitter_sq;
+ max_idx = i;
+ }
+ VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
+ i, selection_jitter_sq);
+ }
+ max_selection_jitter = SQRT(max_selection_jitter);
+ VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
+ max_idx, max_selection_jitter, min_jitter);
+
+ /* If the maximum selection jitter is less than the
+ * minimum peer jitter, then tossing out more survivors
+ * will not lower the minimum peer jitter, so we might
+ * as well stop.
+ */
+ if (max_selection_jitter < min_jitter) {
+ VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
+ max_selection_jitter, min_jitter, num_survivors);
+ break;
+ }
+
+ /* Delete survivor[max_idx] from the list
+ * and go around again.
+ */
+ VERB5 bb_error_msg("dropping survivor %d", max_idx);
+ num_survivors--;
+ while (max_idx < num_survivors) {
+ survivor[max_idx] = survivor[max_idx + 1];
+ max_idx++;
+ }
+ }
+
+ /* Pick the best clock. If the old system peer is on the list
+ * and at the same stratum as the first survivor on the list,
+ * then don't do a clock hop. Otherwise, select the first
+ * survivor on the list as the new system peer.
+ */
+//TODO - see clock_combine()
+ VERB3 bb_error_msg("selected peer %s filter_offset:%f age:%f",
+ survivor[0].p->p_dotted,
+ survivor[0].p->filter_offset,
+ t - survivor[0].p->lastpkt_recv_time
+ );
+ return survivor[0].p;
+}
+
+
+/*
+ * Local clock discipline and its helpers
+ */
+static void
+set_new_values(int disc_state, double offset, double recv_time)
+{
+ /* Enter new state and set state variables. Note we use the time
+ * of the last clock filter sample, which must be earlier than
+ * the current time.
+ */
+ VERB3 bb_error_msg("disc_state=%d last_update_offset=%f last_update_recv_time=%f",
+ disc_state, offset, recv_time);
+ G.discipline_state = disc_state;
+ G.last_update_offset = offset;
+ G.last_update_recv_time = recv_time;
+}
+/* Clock state definitions */
+#define STATE_NSET 0 /* initial state, "nothing is set" */
+#define STATE_FSET 1 /* frequency set from file */
+#define STATE_SPIK 2 /* spike detected */
+#define STATE_FREQ 3 /* initial frequency */
+#define STATE_SYNC 4 /* clock synchronized (normal operation) */
+/* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
+static int
+update_local_clock(peer_t *p, double t)
+{
+ int rc;
+ long old_tmx_offset;
+ struct timex tmx;
+ double offset = p->filter_offset;
+ double recv_time = p->lastpkt_recv_time;
+ double abs_offset;
+ double freq_drift;
+ double since_last_update;
+ double etemp, dtemp;
+
+ abs_offset = fabs(offset);
+
+ /* If the offset is too large, give up and go home */
+ if (abs_offset > PANIC_THRESHOLD) {
+ bb_error_msg_and_die("offset %f far too big, exiting", offset);
+ }
+
+ /* If this is an old update, for instance as the result
+ * of a system peer change, avoid it. We never use
+ * an old sample or the same sample twice.
+ */
+ if (recv_time <= G.last_update_recv_time) {
+ VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it",
+ G.last_update_recv_time, recv_time);
+ return 0; /* "leave poll interval as is" */
+ }
+
+ /* Clock state machine transition function. This is where the
+ * action is and defines how the system reacts to large time
+ * and frequency errors.
+ */
+ since_last_update = recv_time - G.reftime;
+ freq_drift = 0;
+ if (G.discipline_state == STATE_FREQ) {
+ /* Ignore updates until the stepout threshold */
+ if (since_last_update < WATCH_THRESHOLD) {
+ VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
+ WATCH_THRESHOLD - since_last_update);
+ return 0; /* "leave poll interval as is" */
+ }
+ freq_drift = (offset - G.last_update_offset) / since_last_update;
+ }
+
+ /* There are two main regimes: when the
+ * offset exceeds the step threshold and when it does not.
+ */
+ if (abs_offset > STEP_THRESHOLD) {
+ llist_t *item;
+
+ switch (G.discipline_state) {
+ case STATE_SYNC:
+ /* The first outlyer: ignore it, switch to SPIK state */
+ VERB3 bb_error_msg("offset:%f - spike detected", offset);
+ G.discipline_state = STATE_SPIK;
+ return -1; /* "decrease poll interval" */
+
+ case STATE_SPIK:
+ /* Ignore succeeding outlyers until either an inlyer
+ * is found or the stepout threshold is exceeded.
+ */
+ if (since_last_update < WATCH_THRESHOLD) {
+ VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains",
+ WATCH_THRESHOLD - since_last_update);
+ return -1; /* "decrease poll interval" */
+ }
+ /* fall through: we need to step */
+ } /* switch */
+
+ /* Step the time and clamp down the poll interval.
+ *
+ * In NSET state an initial frequency correction is
+ * not available, usually because the frequency file has
+ * not yet been written. Since the time is outside the
+ * capture range, the clock is stepped. The frequency
+ * will be set directly following the stepout interval.
+ *
+ * In FSET state the initial frequency has been set
+ * from the frequency file. Since the time is outside
+ * the capture range, the clock is stepped immediately,
+ * rather than after the stepout interval. Guys get
+ * nervous if it takes 17 minutes to set the clock for
+ * the first time.
+ *
+ * In SPIK state the stepout threshold has expired and
+ * the phase is still above the step threshold. Note
+ * that a single spike greater than the step threshold
+ * is always suppressed, even at the longer poll
+ * intervals.
+ */
+ VERB3 bb_error_msg("stepping time by %f; poll_exp=MINPOLL", offset);
+ step_time(offset);
+ if (option_mask32 & OPT_q) {
+ /* We were only asked to set time once. Done. */
+ exit(0);
+ }
+
+ G.polladj_count = 0;
+ G.poll_exp = MINPOLL;
+ G.stratum = MAXSTRAT;
+ for (item = G.ntp_peers; item != NULL; item = item->link) {
+ peer_t *pp = (peer_t *) item->data;
+ reset_peer_stats(pp, t, offset);
+ }
+ if (G.discipline_state == STATE_NSET) {
+ set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
+ return 1; /* "ok to increase poll interval" */
+ }
+ set_new_values(STATE_SYNC, /*offset:*/ 0, recv_time);
+
+ } else { /* abs_offset <= STEP_THRESHOLD */
+
+ if (G.poll_exp < MINPOLL) {
+ VERB3 bb_error_msg("saw small offset %f, disabling burst mode", offset);
+ G.poll_exp = MINPOLL;
+ }
+
+ /* Compute the clock jitter as the RMS of exponentially
+ * weighted offset differences. Used by the poll adjust code.
+ */
+ etemp = SQUARE(G.discipline_jitter);
+ dtemp = SQUARE(MAXD(fabs(offset - G.last_update_offset), G_precision_sec));
+ G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
+ VERB3 bb_error_msg("discipline jitter=%f", G.discipline_jitter);
+
+ switch (G.discipline_state) {
+ case STATE_NSET:
+ if (option_mask32 & OPT_q) {
+ /* We were only asked to set time once.
+ * The clock is precise enough, no need to step.
+ */
+ exit(0);
+ }
+ /* This is the first update received and the frequency
+ * has not been initialized. The first thing to do
+ * is directly measure the oscillator frequency.
+ */
+ set_new_values(STATE_FREQ, offset, recv_time);
+ VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
+ return -1; /* "decrease poll interval" */
+
+#if 0 /* this is dead code for now */
+ case STATE_FSET:
+ /* This is the first update and the frequency
+ * has been initialized. Adjust the phase, but
+ * don't adjust the frequency until the next update.
+ */
+ set_new_values(STATE_SYNC, offset, recv_time);
+ /* freq_drift remains 0 */
+ break;
+#endif
+
+ case STATE_FREQ:
+ /* since_last_update >= WATCH_THRESHOLD, we waited enough.
+ * Correct the phase and frequency and switch to SYNC state.
+ * freq_drift was already estimated (see code above)
+ */
+ set_new_values(STATE_SYNC, offset, recv_time);
+ break;
+
+ default:
+ /* Compute freq_drift due to PLL and FLL contributions.
+ *
+ * The FLL and PLL frequency gain constants
+ * depend on the poll interval and Allan
+ * intercept. The FLL is not used below one-half
+ * the Allan intercept. Above that the loop gain
+ * increases in steps to 1 / AVG.
+ */
+ if ((1 << G.poll_exp) > ALLAN / 2) {
+ etemp = FLL - G.poll_exp;
+ if (etemp < AVG)
+ etemp = AVG;
+ freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp);
+ }
+ /* For the PLL the integration interval
+ * (numerator) is the minimum of the update
+ * interval and poll interval. This allows
+ * oversampling, but not undersampling.
+ */
+ etemp = MIND(since_last_update, (1 << G.poll_exp));
+ dtemp = (4 * PLL) << G.poll_exp;
+ freq_drift += offset * etemp / SQUARE(dtemp);
+ set_new_values(STATE_SYNC, offset, recv_time);
+ break;
+ }
+ G.stratum = p->lastpkt_stratum + 1;
+ }
+
+ G.reftime = t;
+ G.leap = p->lastpkt_leap;
+ G.refid = p->lastpkt_refid;
+ G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
+ dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(s.jitter));
+ dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (t - p->lastpkt_recv_time) + abs_offset, MINDISP);
+ G.rootdisp = p->lastpkt_rootdisp + dtemp;
+ VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted);
+
+ /* We are in STATE_SYNC now, but did not do adjtimex yet.
+ * (Any other state does not reach this, they all return earlier)
+ * By this time, freq_drift and G.last_update_offset are set
+ * to values suitable for adjtimex.
+ *
+ * Calculate the new frequency drift and frequency stability (wander).
+ * Compute the clock wander as the RMS of exponentially weighted
+ * frequency differences. This is not used directly, but can,
+ * along with the jitter, be a highly useful monitoring and
+ * debugging tool.
+ */
+ dtemp = G.discipline_freq_drift + freq_drift;
+ G.discipline_freq_drift = MAXD(MIND(MAXFREQ, dtemp), -MAXFREQ);
+ etemp = SQUARE(G.discipline_wander);
+ dtemp = SQUARE(dtemp);
+ G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
+
+ VERB3 {
+ bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
+ G.discipline_freq_drift,
+ (long)(G.discipline_freq_drift * 65536e6),
+ freq_drift,
+ G.discipline_wander);
+ memset(&tmx, 0, sizeof(tmx));
+ if (adjtimex(&tmx) < 0)
+ bb_perror_msg_and_die("adjtimex");
+ VERB3 bb_error_msg("p adjtimex freq:%ld offset:%ld constant:%ld status:0x%x",
+ tmx.freq, tmx.offset, tmx.constant, tmx.status);
+ }
+
+ old_tmx_offset = 0;
+ if (!G.adjtimex_was_done) {
+ G.adjtimex_was_done = 1;
+ /* When we use adjtimex for the very first time,
+ * we need to ADD to pre-existing tmx.offset - it may be !0
+ */
+ memset(&tmx, 0, sizeof(tmx));
+ if (adjtimex(&tmx) < 0)
+ bb_perror_msg_and_die("adjtimex");
+ old_tmx_offset = tmx.offset;
+ }
+ memset(&tmx, 0, sizeof(tmx));
+#if 0
+//doesn't work, offset remains 0 (!):
+//ntpd: set adjtimex freq:1786097 tmx.offset:77487
+//ntpd: prev adjtimex freq:1786097 tmx.offset:0
+//ntpd: cur adjtimex freq:1786097 tmx.offset:0
+ tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET;
+ /* 65536 is one ppm */
+ tmx.freq = G.discipline_freq_drift * 65536e6;
+ tmx.offset = G.last_update_offset * 1000000; /* usec */
+#endif
+ tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
+ tmx.offset = (G.last_update_offset * 1000000) /* usec */
+ /* + (G.last_update_offset < 0 ? -0.5 : 0.5) - too small to bother */
+ + old_tmx_offset; /* almost always 0 */
+ tmx.status = STA_PLL;
+ //if (sys_leap == LEAP_ADDSECOND)
+ // tmx.status |= STA_INS;
+ //else if (sys_leap == LEAP_DELSECOND)
+ // tmx.status |= STA_DEL;
+ tmx.constant = G.poll_exp - 4;
+ //tmx.esterror = (u_int32)(clock_jitter * 1e6);
+ //tmx.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
+ VERB3 bb_error_msg("b adjtimex freq:%ld offset:%ld constant:%ld status:0x%x",
+ tmx.freq, tmx.offset, tmx.constant, tmx.status);
+ rc = adjtimex(&tmx);
+ if (rc < 0)
+ bb_perror_msg_and_die("adjtimex");
+ VERB3 {
+ bb_error_msg("adjtimex:%d freq:%ld offset:%ld constant:%ld status:0x%x",
+ rc, tmx.freq, tmx.offset, tmx.constant, tmx.status);
+ memset(&tmx, 0, sizeof(tmx));
+ if (adjtimex(&tmx) < 0)
+ bb_perror_msg_and_die("adjtimex");
+ VERB3 bb_error_msg("c adjtimex freq:%ld offset:%ld constant:%ld status:0x%x",
+ tmx.freq, tmx.offset, tmx.constant, tmx.status);
+ }
+// #define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ - ?
+// it appeared after a while:
+//ntpd: p adjtimex freq:-14545653 offset:-5396 constant:10 status:0x41
+//ntpd: c adjtimex freq:-14547835 offset:-8307 constant:10 status:0x1
+//ntpd: p adjtimex freq:-14547835 offset:-6398 constant:10 status:0x41
+//ntpd: c adjtimex freq:-14550486 offset:-10158 constant:10 status:0x1
+//ntpd: p adjtimex freq:-14550486 offset:-6132 constant:10 status:0x41
+//ntpd: c adjtimex freq:-14636129 offset:-10158 constant:10 status:0x4001
+//ntpd: p adjtimex freq:-14636129 offset:-10002 constant:10 status:0x4041
+//ntpd: c adjtimex freq:-14636245 offset:-7497 constant:10 status:0x1
+//ntpd: p adjtimex freq:-14636245 offset:-4573 constant:10 status:0x41
+//ntpd: c adjtimex freq:-14642034 offset:-11715 constant:10 status:0x1
+//ntpd: p adjtimex freq:-14642034 offset:-4098 constant:10 status:0x41
+//ntpd: c adjtimex freq:-14699112 offset:-11746 constant:10 status:0x4001
+//ntpd: p adjtimex freq:-14699112 offset:-4239 constant:10 status:0x4041
+//ntpd: c adjtimex freq:-14762330 offset:-12786 constant:10 status:0x4001
+//ntpd: p adjtimex freq:-14762330 offset:-4434 constant:10 status:0x4041
+//ntpd: b adjtimex freq:0 offset:-9669 constant:8 status:0x1
+//ntpd: adjtimex:0 freq:-14809095 offset:-9669 constant:10 status:0x4001
+//ntpd: c adjtimex freq:-14809095 offset:-9669 constant:10 status:0x4001
+
+ return 1; /* "ok to increase poll interval" */
+}
+
+
+/*
+ * We've got a new reply packet from a peer, process it
+ * (helpers first)
+ */
+static unsigned
+retry_interval(void)
+{
+ /* Local problem, want to retry soon */
+ unsigned interval, r;
+ interval = RETRY_INTERVAL;
+ r = random();
+ interval += r % (unsigned)(RETRY_INTERVAL / 4);
+ VERB3 bb_error_msg("chose retry interval:%u", interval);
+ return interval;
+}
+static unsigned
+poll_interval(int exponent) /* exp is always -1 or 0 */
+{
+ /* Want to send next packet at (1 << G.poll_exp) + small random value */
+ unsigned interval, r;
+ exponent += G.poll_exp; /* G.poll_exp is always > 0 */
+ /* never true: if (exp < 0) exp = 0; */
+ interval = 1 << exponent;
+ r = random();
+ interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
+ VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
+ return interval;
+}
+static void
+recv_and_process_peer_pkt(peer_t *p)
+{
+ int rc;
+ ssize_t size;
+ msg_t msg;
+ double T1, T2, T3, T4;
+ unsigned interval;
+ datapoint_t *datapoint;
+ peer_t *q;
+
+ /* We can recvfrom here and check from.IP, but some multihomed
+ * ntp servers reply from their *other IP*.
+ * TODO: maybe we should check at least what we can: from.port == 123?
+ */
+ size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
+ if (size == -1) {
+ bb_perror_msg("recv(%s) error", p->p_dotted);
+ if (errno == EHOSTUNREACH || errno == EHOSTDOWN
+ || errno == ENETUNREACH || errno == ENETDOWN
+ || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
+ || errno == EAGAIN
+ ) {
+//TODO: always do this?
+ set_next(p, retry_interval());
+ goto close_sock;
+ }
+ xfunc_die();
+ }
+
+ if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
+ bb_error_msg("malformed packet received from %s", p->p_dotted);
+ goto bail;
+ }
+
+ if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
+ || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
+ ) {
+ goto bail;
+ }
+
+ if ((msg.m_status & LI_ALARM) == LI_ALARM
+ || msg.m_stratum == 0
+ || msg.m_stratum > NTP_MAXSTRATUM
+ ) {
+// TODO: stratum 0 responses may have commands in 32-bit m_refid field:
+// "DENY", "RSTR" - peer does not like us at all
+// "RATE" - peer is overloaded, reduce polling freq
+ interval = poll_interval(0);
+ bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
+ goto close_sock;
+ }
+
+// /*
+// * Verify the server is synchronized with valid stratum and
+// * reference time not later than the transmit time.
+// */
+// if (p->lastpkt_leap == NOSYNC || p->lastpkt_stratum >= MAXSTRAT)
+// return; /* unsynchronized */
+//
+// /* Verify valid root distance */
+// if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
+// return; /* invalid header values */
+
+ p->lastpkt_leap = msg.m_status;
+ p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
+ p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
+ p->lastpkt_refid = msg.m_refid;
+
+ /*
+ * From RFC 2030 (with a correction to the delay math):
+ *
+ * Timestamp Name ID When Generated
+ * ------------------------------------------------------------
+ * Originate Timestamp T1 time request sent by client
+ * Receive Timestamp T2 time request received by server
+ * Transmit Timestamp T3 time reply sent by server
+ * Destination Timestamp T4 time reply received by client
+ *
+ * The roundtrip delay and local clock offset are defined as
+ *
+ * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
+ */
+ T1 = p->p_xmttime;
+ T2 = lfp_to_d(msg.m_rectime);
+ T3 = lfp_to_d(msg.m_xmttime);
+ T4 = gettime1900d();
+
+ p->lastpkt_recv_time = T4;
+
+ VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
+ p->datapoint_idx = p->p_reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
+ datapoint = &p->filter_datapoint[p->datapoint_idx];
+ datapoint->d_recv_time = T4;
+ datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
+ /* The delay calculation is a special case. In cases where the
+ * server and client clocks are running at different rates and
+ * with very fast networks, the delay can appear negative. In
+ * order to avoid violating the Principle of Least Astonishment,
+ * the delay is clamped not less than the system precision.
+ */
+ p->lastpkt_delay = (T4 - T1) - (T3 - T2);
+ datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
+ if (!p->p_reachable_bits) {
+ /* 1st datapoint ever - replicate offset in every element */
+ int i;
+ for (i = 1; i < NUM_DATAPOINTS; i++) {
+ p->filter_datapoint[i].d_offset = datapoint->d_offset;
+ }
+ }
+
+ p->p_reachable_bits |= 1;
+ VERB1 {
+ bb_error_msg("reply from %s: reach 0x%02x offset %f delay %f",
+ p->p_dotted,
+ p->p_reachable_bits,
+ datapoint->d_offset, p->lastpkt_delay);
+ }
+
+ /* Muck with statictics and update the clock */
+ filter_datapoints(p, T4);
+ q = select_and_cluster(T4);
+ rc = -1;
+ if (q)
+ rc = update_local_clock(q, T4);
+
+ if (rc != 0) {
+ /* Adjust the poll interval by comparing the current offset
+ * with the clock jitter. If the offset is less than
+ * the clock jitter times a constant, then the averaging interval
+ * is increased, otherwise it is decreased. A bit of hysteresis
+ * helps calm the dance. Works best using burst mode.
+ */
+ VERB4 if (rc > 0) {
+ bb_error_msg("offset:%f POLLADJ_GATE*discipline_jitter:%f poll:%s",
+ q->filter_offset, POLLADJ_GATE * G.discipline_jitter,
+ fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter
+ ? "grows" : "falls"
+ );
+ }
+ if (rc > 0 && fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter) {
+ G.polladj_count += G.poll_exp;
+ if (G.polladj_count > POLLADJ_LIMIT) {
+ G.polladj_count = 0;
+ if (G.poll_exp < MAXPOLL) {
+ G.poll_exp++;
+ VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
+ G.discipline_jitter, G.poll_exp);
+ }
+ } else {
+ VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count);
+ }
+ } else {
+ G.polladj_count -= G.poll_exp * 2;
+ if (G.polladj_count < -POLLADJ_LIMIT) {
+ G.polladj_count = 0;
+ if (G.poll_exp > MINPOLL) {
+ G.poll_exp--;
+ VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
+ G.discipline_jitter, G.poll_exp);
+ }
+ } else {
+ VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count);
+ }
+ }
+ }
+
+ /* Decide when to send new query for this peer */
+ interval = poll_interval(0);
+ set_next(p, interval);
+
+ close_sock:
+ /* We do not expect any more packets from this peer for now.
+ * Closing the socket informs kernel about it.
+ * We open a new socket when we send a new query.
+ */
+ close(p->p_fd);
+ p->p_fd = -1;
+ bail:
+ return;
+}
+
+#if ENABLE_FEATURE_NTPD_SERVER
+static void
+recv_and_process_client_pkt(void /*int fd*/)
+{
+ ssize_t size;
+ uint8_t version;
+ double rectime;
+ len_and_sockaddr *to;
+ struct sockaddr *from;
+ msg_t msg;
+ uint8_t query_status;
+ l_fixedpt_t query_xmttime;
+
+ to = get_sock_lsa(G.listen_fd);
+ from = xzalloc(to->len);
+
+ size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
+ if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
+ char *addr;
+ if (size < 0) {
+ if (errno == EAGAIN)
+ goto bail;
+ bb_perror_msg_and_die("recv");
+ }
+ addr = xmalloc_sockaddr2dotted_noport(from);
+ bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
+ free(addr);
+ goto bail;
+ }
+
+ query_status = msg.m_status;
+ query_xmttime = msg.m_xmttime;
+
+ /* Build a reply packet */
+ memset(&msg, 0, sizeof(msg));
+ msg.m_status = G.stratum < MAXSTRAT ? G.leap : LI_ALARM;
+ msg.m_status |= (query_status & VERSION_MASK);
+ msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
+ MODE_SERVER : MODE_SYM_PAS;
+ msg.m_stratum = G.stratum;
+ msg.m_ppoll = G.poll_exp;
+ msg.m_precision_exp = G_precision_exp;
+ rectime = gettime1900d();
+ msg.m_xmttime = msg.m_rectime = d_to_lfp(rectime);
+ msg.m_reftime = d_to_lfp(G.reftime);
+ msg.m_orgtime = query_xmttime;
+ msg.m_rootdelay = d_to_sfp(G.rootdelay);
+//simple code does not do this, fix simple code!
+ msg.m_rootdisp = d_to_sfp(G.rootdisp);
+ version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
+ msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3;
+
+ /* We reply from the local address packet was sent to,
+ * this makes to/from look swapped here: */
+ do_sendto(G.listen_fd,
+ /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
+ &msg, size);
+
+ bail:
+ free(to);
+ free(from);
+}
+#endif
+
+/* Upstream ntpd's options:
+ *
+ * -4 Force DNS resolution of host names to the IPv4 namespace.
+ * -6 Force DNS resolution of host names to the IPv6 namespace.
+ * -a Require cryptographic authentication for broadcast client,
+ * multicast client and symmetric passive associations.
+ * This is the default.
+ * -A Do not require cryptographic authentication for broadcast client,
+ * multicast client and symmetric passive associations.
+ * This is almost never a good idea.
+ * -b Enable the client to synchronize to broadcast servers.
+ * -c conffile
+ * Specify the name and path of the configuration file,
+ * default /etc/ntp.conf
+ * -d Specify debugging mode. This option may occur more than once,
+ * with each occurrence indicating greater detail of display.
+ * -D level
+ * Specify debugging level directly.
+ * -f driftfile
+ * Specify the name and path of the frequency file.
+ * This is the same operation as the "driftfile FILE"
+ * configuration command.
+ * -g Normally, ntpd exits with a message to the system log
+ * if the offset exceeds the panic threshold, which is 1000 s
+ * by default. This option allows the time to be set to any value
+ * without restriction; however, this can happen only once.
+ * If the threshold is exceeded after that, ntpd will exit
+ * with a message to the system log. This option can be used
+ * with the -q and -x options. See the tinker command for other options.
+ * -i jaildir
+ * Chroot the server to the directory jaildir. This option also implies
+ * that the server attempts to drop root privileges at startup
+ * (otherwise, chroot gives very little additional security).
+ * You may need to also specify a -u option.
+ * -k keyfile
+ * Specify the name and path of the symmetric key file,
+ * default /etc/ntp/keys. This is the same operation
+ * as the "keys FILE" configuration command.
+ * -l logfile
+ * Specify the name and path of the log file. The default
+ * is the system log file. This is the same operation as
+ * the "logfile FILE" configuration command.
+ * -L Do not listen to virtual IPs. The default is to listen.
+ * -n Don't fork.
+ * -N To the extent permitted by the operating system,
+ * run the ntpd at the highest priority.
+ * -p pidfile
+ * Specify the name and path of the file used to record the ntpd
+ * process ID. This is the same operation as the "pidfile FILE"
+ * configuration command.
+ * -P priority
+ * To the extent permitted by the operating system,
+ * run the ntpd at the specified priority.
+ * -q Exit the ntpd just after the first time the clock is set.
+ * This behavior mimics that of the ntpdate program, which is
+ * to be retired. The -g and -x options can be used with this option.
+ * Note: The kernel time discipline is disabled with this option.
+ * -r broadcastdelay
+ * Specify the default propagation delay from the broadcast/multicast
+ * server to this client. This is necessary only if the delay
+ * cannot be computed automatically by the protocol.
+ * -s statsdir
+ * Specify the directory path for files created by the statistics
+ * facility. This is the same operation as the "statsdir DIR"
+ * configuration command.
+ * -t key
+ * Add a key number to the trusted key list. This option can occur
+ * more than once.
+ * -u user[:group]
+ * Specify a user, and optionally a group, to switch to.
+ * -v variable
+ * -V variable
+ * Add a system variable listed by default.
+ * -x Normally, the time is slewed if the offset is less than the step
+ * threshold, which is 128 ms by default, and stepped if above
+ * the threshold. This option sets the threshold to 600 s, which is
+ * well within the accuracy window to set the clock manually.
+ * Note: since the slew rate of typical Unix kernels is limited
+ * to 0.5 ms/s, each second of adjustment requires an amortization
+ * interval of 2000 s. Thus, an adjustment as much as 600 s
+ * will take almost 14 days to complete. This option can be used
+ * with the -g and -q options. See the tinker command for other options.
+ * Note: The kernel time discipline is disabled with this option.
+ */
+
+/* By doing init in a separate function we decrease stack usage
+ * in main loop.
+ */
+static NOINLINE void ntp_init(char **argv)
+{
+ unsigned opts;
+ llist_t *peers;
+
+ srandom(getpid());
+
+ if (getuid())
+ bb_error_msg_and_die(bb_msg_you_must_be_root);
+
+ /* Set some globals */
+#if 0
+ /* With constant b = 100, G.precision_exp is also constant -6.
+ * Uncomment this to verify.
+ */
+ {
+ int prec = 0;
+ int b;
+# if 0
+ struct timespec tp;
+ /* We can use sys_clock_getres but assuming 10ms tick should be fine */
+ clock_getres(CLOCK_REALTIME, &tp);
+ tp.tv_sec = 0;
+ tp.tv_nsec = 10000000;
+ b = 1000000000 / tp.tv_nsec; /* convert to Hz */
+# else
+ b = 100; /* b = 1000000000/10000000 = 100 */
+# endif
+ while (b > 1)
+ prec--, b >>= 1;
+ /*G.precision_exp = prec;*/
+ /*G.precision_sec = (1.0 / (1 << (- prec)));*/
+ bb_error_msg("G.precision_exp:%d sec:%f", prec, G_precision_sec); /* -6 */
+ }
+#endif
+ G.stratum = MAXSTRAT;
+ G.poll_exp = 1; /* should use MINPOLL, but 1 speeds up initial sync */
+ G.reftime = G.last_update_recv_time = gettime1900d();
+
+ /* Parse options */
+ peers = NULL;
+ opt_complementary = "dd:p::"; /* d: counter, p: list */
+ opts = getopt32(argv,
+ "nqNx" /* compat */
+ "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
+ "d" /* compat */
+ "46aAbgL", /* compat, ignored */
+ &peers, &G.verbose);
+ if (!(opts & (OPT_p|OPT_l)))
+ bb_show_usage();
+// if (opts & OPT_x) /* disable stepping, only slew is allowed */
+// G.time_was_stepped = 1;
+ while (peers)
+ add_peers(llist_pop(&peers));
+ if (!(opts & OPT_n)) {
+ bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
+ logmode = LOGMODE_NONE;
+ }
+#if ENABLE_FEATURE_NTPD_SERVER
+ G.listen_fd = -1;
+ if (opts & OPT_l) {
+ G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
+ socket_want_pktinfo(G.listen_fd);
+ setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
+ }
+#endif
+ /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
+ if (opts & OPT_N)
+ setpriority(PRIO_PROCESS, 0, -15);
+
+ bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo);
+ bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN);
+}
+
+int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int ntpd_main(int argc UNUSED_PARAM, char **argv)
+{
+ struct globals g;
+ struct pollfd *pfd;
+ peer_t **idx2peer;
+
+ memset(&g, 0, sizeof(g));
+ SET_PTR_TO_GLOBALS(&g);
+
+ ntp_init(argv);
+
+ {
+ /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
+ unsigned cnt = g.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
+ idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
+ pfd = xzalloc(sizeof(pfd[0]) * cnt);
+ }
+
+ while (!bb_got_signal) {
+ llist_t *item;
+ unsigned i, j;
+ unsigned sent_cnt, trial_cnt;
+ int nfds, timeout;
+ time_t cur_time, nextaction;
+
+ /* Nothing between here and poll() blocks for any significant time */
+
+ cur_time = time(NULL);
+ nextaction = cur_time + 3600;
+
+ i = 0;
+#if ENABLE_FEATURE_NTPD_SERVER
+ if (g.listen_fd != -1) {
+ pfd[0].fd = g.listen_fd;
+ pfd[0].events = POLLIN;
+ i++;
+ }
+#endif
+ /* Pass over peer list, send requests, time out on receives */
+ sent_cnt = trial_cnt = 0;
+ for (item = g.ntp_peers; item != NULL; item = item->link) {
+ peer_t *p = (peer_t *) item->data;
+
+ /* Overflow-safe "if (p->next_action_time <= cur_time) ..." */
+ if ((int)(cur_time - p->next_action_time) >= 0) {
+ if (p->p_fd == -1) {
+ /* Time to send new req */
+ trial_cnt++;
+ if (send_query_to_peer(p) == 0)
+ sent_cnt++;
+ } else {
+ /* Timed out waiting for reply */
+ close(p->p_fd);
+ p->p_fd = -1;
+ timeout = poll_interval(-1); /* try a bit faster */
+ bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
+ p->p_dotted, p->p_reachable_bits, timeout);
+ set_next(p, timeout);
+ }
+ }
+
+ if (p->next_action_time < nextaction)
+ nextaction = p->next_action_time;
+
+ if (p->p_fd >= 0) {
+ /* Wait for reply from this peer */
+ pfd[i].fd = p->p_fd;
+ pfd[i].events = POLLIN;
+ idx2peer[i] = p;
+ i++;
+ }
+ }
+
+// if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0) {
+// G.time_was_stepped = 1;
+// }
+
+ timeout = nextaction - cur_time;
+ if (timeout < 1)
+ timeout = 1;
+
+ /* Here we may block */
+ VERB2 bb_error_msg("poll %us, sockets:%u", timeout, i);
+ nfds = poll(pfd, i, timeout * 1000);
+ if (nfds <= 0)
+ continue;
+
+ /* Process any received packets */
+ j = 0;
+#if ENABLE_FEATURE_NTPD_SERVER
+ if (g.listen_fd != -1) {
+ if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
+ nfds--;
+ recv_and_process_client_pkt(/*g.listen_fd*/);
+ }
+ j = 1;
+ }
+#endif
+ for (; nfds != 0 && j < i; j++) {
+ if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
+ nfds--;
+ recv_and_process_peer_pkt(idx2peer[j]);
+ }
+ }
+ } /* while (!bb_got_signal) */
+
+ kill_myself_with_sig(bb_got_signal);
+}
+
+
+
+
+
+
+/*** openntpd-4.6 uses only adjtime, not adjtimex ***/
+
+/*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/
+
+#if 0
+static double
+direct_freq(double fp_offset)
+{
+
+#ifdef KERNEL_PLL
+ /*
+ * If the kernel is enabled, we need the residual offset to
+ * calculate the frequency correction.
+ */
+ if (pll_control && kern_enable) {
+ memset(&ntv, 0, sizeof(ntv));
+ ntp_adjtime(&ntv);
+#ifdef STA_NANO
+ clock_offset = ntv.offset / 1e9;
+#else /* STA_NANO */
+ clock_offset = ntv.offset / 1e6;
+#endif /* STA_NANO */
+ drift_comp = FREQTOD(ntv.freq);
+ }
+#endif /* KERNEL_PLL */
+ set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp);
+ wander_resid = 0;
+ return drift_comp;
+}
+
+static void
+set_freq(double freq) /* frequency update */
+{
+ char tbuf[80];
+
+ drift_comp = freq;
+
+#ifdef KERNEL_PLL
+ /*
+ * If the kernel is enabled, update the kernel frequency.
+ */
+ if (pll_control && kern_enable) {
+ memset(&ntv, 0, sizeof(ntv));
+ ntv.modes = MOD_FREQUENCY;
+ ntv.freq = DTOFREQ(drift_comp);
+ ntp_adjtime(&ntv);
+ snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6);
+ report_event(EVNT_FSET, NULL, tbuf);
+ } else {
+ snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
+ report_event(EVNT_FSET, NULL, tbuf);
+ }
+#else /* KERNEL_PLL */
+ snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
+ report_event(EVNT_FSET, NULL, tbuf);
+#endif /* KERNEL_PLL */
+}
+
+...
+...
+...
+
+#ifdef KERNEL_PLL
+ /*
+ * This code segment works when clock adjustments are made using
+ * precision time kernel support and the ntp_adjtime() system
+ * call. This support is available in Solaris 2.6 and later,
+ * Digital Unix 4.0 and later, FreeBSD, Linux and specially
+ * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
+ * DECstation 5000/240 and Alpha AXP, additional kernel
+ * modifications provide a true microsecond clock and nanosecond
+ * clock, respectively.
+ *
+ * Important note: The kernel discipline is used only if the
+ * step threshold is less than 0.5 s, as anything higher can
+ * lead to overflow problems. This might occur if some misguided
+ * lad set the step threshold to something ridiculous.
+ */
+ if (pll_control && kern_enable) {
+
+#define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST)
+
+ /*
+ * We initialize the structure for the ntp_adjtime()
+ * system call. We have to convert everything to
+ * microseconds or nanoseconds first. Do not update the
+ * system variables if the ext_enable flag is set. In
+ * this case, the external clock driver will update the
+ * variables, which will be read later by the local
+ * clock driver. Afterwards, remember the time and
+ * frequency offsets for jitter and stability values and
+ * to update the frequency file.
+ */
+ memset(&ntv, 0, sizeof(ntv));
+ if (ext_enable) {
+ ntv.modes = MOD_STATUS;
+ } else {
+#ifdef STA_NANO
+ ntv.modes = MOD_BITS | MOD_NANO;
+#else /* STA_NANO */
+ ntv.modes = MOD_BITS;
+#endif /* STA_NANO */
+ if (clock_offset < 0)
+ dtemp = -.5;
+ else
+ dtemp = .5;
+#ifdef STA_NANO
+ ntv.offset = (int32)(clock_offset * 1e9 + dtemp);
+ ntv.constant = sys_poll;
+#else /* STA_NANO */
+ ntv.offset = (int32)(clock_offset * 1e6 + dtemp);
+ ntv.constant = sys_poll - 4;
+#endif /* STA_NANO */
+ ntv.esterror = (u_int32)(clock_jitter * 1e6);
+ ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
+ ntv.status = STA_PLL;
+
+ /*
+ * Enable/disable the PPS if requested.
+ */
+ if (pps_enable) {
+ if (!(pll_status & STA_PPSTIME))
+ report_event(EVNT_KERN,
+ NULL, "PPS enabled");
+ ntv.status |= STA_PPSTIME | STA_PPSFREQ;
+ } else {
+ if (pll_status & STA_PPSTIME)
+ report_event(EVNT_KERN,
+ NULL, "PPS disabled");
+ ntv.status &= ~(STA_PPSTIME |
+ STA_PPSFREQ);
+ }
+ if (sys_leap == LEAP_ADDSECOND)
+ ntv.status |= STA_INS;
+ else if (sys_leap == LEAP_DELSECOND)
+ ntv.status |= STA_DEL;
+ }
+
+ /*
+ * Pass the stuff to the kernel. If it squeals, turn off
+ * the pps. In any case, fetch the kernel offset,
+ * frequency and jitter.
+ */
+ if (ntp_adjtime(&ntv) == TIME_ERROR) {
+ if (!(ntv.status & STA_PPSSIGNAL))
+ report_event(EVNT_KERN, NULL,
+ "PPS no signal");
+ }
+ pll_status = ntv.status;
+#ifdef STA_NANO
+ clock_offset = ntv.offset / 1e9;
+#else /* STA_NANO */
+ clock_offset = ntv.offset / 1e6;
+#endif /* STA_NANO */
+ clock_frequency = FREQTOD(ntv.freq);
+
+ /*
+ * If the kernel PPS is lit, monitor its performance.
+ */
+ if (ntv.status & STA_PPSTIME) {
+#ifdef STA_NANO
+ clock_jitter = ntv.jitter / 1e9;
+#else /* STA_NANO */
+ clock_jitter = ntv.jitter / 1e6;
+#endif /* STA_NANO */
+ }
+
+#if defined(STA_NANO) && NTP_API == 4
+ /*
+ * If the TAI changes, update the kernel TAI.
+ */
+ if (loop_tai != sys_tai) {
+ loop_tai = sys_tai;
+ ntv.modes = MOD_TAI;
+ ntv.constant = sys_tai;
+ ntp_adjtime(&ntv);
+ }
+#endif /* STA_NANO */
+ }
+#endif /* KERNEL_PLL */
+#endif
projects / oweals / busybox.git / commitdiff