[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/app/busybox/src/networking/ntpd.c b/ap/app/busybox/src/networking/ntpd.c
new file mode 100644
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+++ b/ap/app/busybox/src/networking/ntpd.c
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+/*
+ * NTP client/server, based on OpenNTPD 3.9p1
+ *
+ * Author: Adam Tkac <vonsch@gmail.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ *
+ * Parts of OpenNTPD clock syncronization code is replaced by
+ * code which is based on ntp-4.2.6, whuch 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. *
+ * *
+ ***********************************************************************
+ */
+
+//usage:#define ntpd_trivial_usage
+//usage: "[-dnqNw"IF_FEATURE_NTPD_SERVER("l")"] [-S PROG] [-p PEER]..."
+//usage:#define ntpd_full_usage "\n\n"
+//usage: "NTP client/server\n"
+//usage: "\n -d Verbose"
+//usage: "\n -n Do not daemonize"
+//usage: "\n -q Quit after clock is set"
+//usage: "\n -N Run at high priority"
+//usage: "\n -w Do not set time (only query peers), implies -n"
+//usage: IF_FEATURE_NTPD_SERVER(
+//usage: "\n -l Run as server on port 123"
+//usage: )
+//usage: "\n -S PROG Run PROG after stepping time, stratum change, and every 11 mins"
+//usage: "\n -p PEER Obtain time from PEER (may be repeated)"
+
+#include "libbb.h"
+#include <math.h>
+#include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
+#include <sys/resource.h> /* setpriority */
+#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
+
+
+/* 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
+
+
+/* High-level description of the algorithm:
+ *
+ * We start running with very small poll_exp, BURSTPOLL,
+ * in order to quickly accumulate INITIAL_SAMPLES datapoints
+ * for each peer. Then, time is stepped if the offset is larger
+ * than STEP_THRESHOLD, otherwise it isn't; anyway, we enlarge
+ * poll_exp to MINPOLL and enter frequency measurement step:
+ * we collect new datapoints but ignore them for WATCH_THRESHOLD
+ * seconds. After WATCH_THRESHOLD seconds we look at accumulated
+ * offset and estimate frequency drift.
+ *
+ * (frequency measurement step seems to not be strictly needed,
+ * it is conditionally disabled with USING_INITIAL_FREQ_ESTIMATION
+ * define set to 0)
+ *
+ * After this, we enter "steady state": we collect a datapoint,
+ * we select the best peer, if this datapoint is not a new one
+ * (IOW: if this datapoint isn't for selected peer), sleep
+ * and collect another one; otherwise, use its offset to update
+ * frequency drift, if offset is somewhat large, reduce poll_exp,
+ * otherwise increase poll_exp.
+ *
+ * If offset is larger than STEP_THRESHOLD, which shouldn't normally
+ * happen, we assume that something "bad" happened (computer
+ * was hibernated, someone set totally wrong date, etc),
+ * then the time is stepped, all datapoints are discarded,
+ * and we go back to steady state.
+ */
+
+#define RETRY_INTERVAL 5 /* on error, retry in N secs */
+#define RESPONSE_INTERVAL 15 /* wait for reply up to N secs */
+#define INITIAL_SAMPLES 4 /* how many samples do we want for init */
+
+/* Clock discipline parameters and constants */
+
+/* Step threshold (sec). std ntpd uses 0.128.
+ * Using exact power of 2 (1/8) results in smaller code */
+#define STEP_THRESHOLD 0.125
+#define WATCH_THRESHOLD 128 /* stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */
+/* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */
+//UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */
+
+#define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */
+#define BURSTPOLL 0 /* initial poll */
+#define MINPOLL 5 /* minimum poll interval. std ntpd uses 6 (6: 64 sec) */
+/* If offset > discipline_jitter * POLLADJ_GATE, and poll interval is >= 2^BIGPOLL,
+ * then it is decreased _at once_. (If < 2^BIGPOLL, it will be decreased _eventually_).
+ */
+#define BIGPOLL 10 /* 2^10 sec ~= 17 min */
+#define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h). std ntpd uses 17 */
+/* Actively lower poll when we see such big offsets.
+ * With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively
+ * if offset increases over ~0.04 sec */
+#define POLLDOWN_OFFSET (STEP_THRESHOLD / 3)
+#define MINDISP 0.01 /* minimum dispersion (sec) */
+#define MAXDISP 16 /* maximum dispersion (sec) */
+#define MAXSTRAT 16 /* maximum stratum (infinity metric) */
+#define MAXDIST 1 /* distance threshold (sec) */
+#define MIN_SELECTED 1 /* minimum intersection survivors */
+#define MIN_CLUSTERED 3 /* minimum cluster survivors */
+
+#define MAXDRIFT 0.000500 /* frequency drift we can correct (500 PPM) */
+
+/* Poll-adjust threshold.
+ * When we see that offset is small enough compared to discipline jitter,
+ * we grow a counter: += MINPOLL. When counter goes over POLLADJ_LIMIT,
+ * we poll_exp++. If offset isn't small, counter -= poll_exp*2,
+ * and when it goes below -POLLADJ_LIMIT, we poll_exp--.
+ * (Bumped from 30 to 40 since otherwise I often see poll_exp going *2* steps down)
+ */
+#define POLLADJ_LIMIT 40
+/* If offset < discipline_jitter * POLLADJ_GATE, then we decide to increase
+ * poll interval (we think we can't improve timekeeping
+ * by staying at smaller poll).
+ */
+#define POLLADJ_GATE 4
+#define TIMECONST_HACK_GATE 2
+/* Compromise Allan intercept (sec). 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
+
+
+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_offset;
+ double d_recv_time;
+ double d_dispersion;
+} datapoint_t;
+
+typedef struct {
+ len_and_sockaddr *p_lsa;
+ char *p_dotted;
+ int p_fd;
+ int datapoint_idx;
+ uint32_t lastpkt_refid;
+ uint8_t lastpkt_status;
+ uint8_t lastpkt_stratum;
+ uint8_t reachable_bits;
+ /* when to send new query (if p_fd == -1)
+ * or when receive times out (if p_fd >= 0): */
+ double next_action_time;
+ 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;
+
+
+#define USING_KERNEL_PLL_LOOP 1
+#define USING_INITIAL_FREQ_ESTIMATION 0
+
+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_w = (1 << 4),
+ OPT_p = (1 << 5),
+ OPT_S = (1 << 6),
+ OPT_l = (1 << 7) * ENABLE_FEATURE_NTPD_SERVER,
+ /* We hijack some bits for other purposes */
+ OPT_qq = (1 << 31),
+};
+
+struct globals {
+ double cur_time;
+ /* 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;
+
+ double last_script_run;
+ char *script_name;
+ llist_t *ntp_peers;
+#if ENABLE_FEATURE_NTPD_SERVER
+ int listen_fd;
+# define G_listen_fd (G.listen_fd)
+#else
+# define G_listen_fd (-1)
+#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 ntp_status;
+ /* 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 clamped down to precision.
+ *
+ * If precision_sec is too large, discipline_jitter gets clamped to it
+ * and if offset is smaller than discipline_jitter * POLLADJ_GATE, poll
+ * interval grows even though we really can benefit from staying at
+ * smaller one, collecting non-lagged datapoits and correcting offset.
+ * (Lagged datapoits exist when poll_exp is large but we still have
+ * systematic offset error - the time distance between datapoints
+ * is significant 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_sec far too small would result in futile
+ * attempts to syncronize to an unachievable precision.
+ *
+ * -6 is 1/64 sec, -7 is 1/128 sec and so on.
+ * -8 is 1/256 ~= 0.003906 (worked well for me --vda)
+ * -9 is 1/512 ~= 0.001953 (let's try this for some time)
+ */
+#define G_precision_exp -9
+ /*
+ * G_precision_exp is used only for construction outgoing packets.
+ * It's ok to set G_precision_sec to a slightly different value
+ * (One which is "nicer looking" in logs).
+ * Exact value would be (1.0 / (1 << (- G_precision_exp))):
+ */
+#define G_precision_sec 0.002
+ uint8_t stratum;
+ /* Bool. After set to 1, never goes back to 0: */
+ smallint initial_poll_complete;
+
+#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) */
+ uint8_t discipline_state; // doc calls it c.state
+ uint8_t poll_exp; // s.poll
+ int polladj_count; // c.count
+ long kernel_freq_drift;
+ peer_t *last_update_peer;
+ double last_update_offset; // c.last
+ double last_update_recv_time; // s.t
+ double discipline_jitter; // c.jitter
+ /* Since we only compare it with ints, can simplify code
+ * by not making this variable floating point:
+ */
+ unsigned offset_to_jitter_ratio;
+ //double cluster_offset; // s.offset
+ //double cluster_jitter; // s.jitter
+#if !USING_KERNEL_PLL_LOOP
+ double discipline_freq_drift; // c.freq
+ /* Maybe conditionally calculate wander? it's used only for logging */
+ double discipline_wander; // c.wander
+#endif
+};
+#define G (*ptr_to_globals)
+
+static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
+
+
+#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)
+
+
+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;
+}
+static NOINLINE double my_SQRT(double X)
+{
+ union {
+ float f;
+ int32_t i;
+ } v;
+ double invsqrt;
+ double Xhalf = X * 0.5;
+
+ /* Fast and good approximation to 1/sqrt(X), black magic */
+ v.f = X;
+ /*v.i = 0x5f3759df - (v.i >> 1);*/
+ v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
+ invsqrt = v.f; /* better than 0.2% accuracy */
+
+ /* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
+ * f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
+ * f'(x) = -2/(x*x*x)
+ * f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
+ * x1 = x0 - (X*x0*x0*x0/2 - x0/2) = 1.5*x0 - X*x0*x0*x0/2 = x0*(1.5 - (X/2)*x0*x0)
+ */
+ invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
+ /* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
+ /* With 4 iterations, more than half results will be exact,
+ * at 6th iterations result stabilizes with about 72% results exact.
+ * We are well satisfied with 0.05% accuracy.
+ */
+
+ return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
+}
+static ALWAYS_INLINE double SQRT(double X)
+{
+ /* If this arch doesn't use IEEE 754 floats, fall back to using libm */
+ if (sizeof(float) != 4)
+ return sqrt(X);
+
+ /* This avoids needing libm, saves about 0.5k on x86-32 */
+ return my_SQRT(X);
+}
+
+static double
+gettime1900d(void)
+{
+ struct timeval tv;
+ gettimeofday(&tv, NULL); /* never fails */
+ G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
+ return G.cur_time;
+}
+
+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)
+{
+ return dp->d_dispersion + FREQ_TOLERANCE * (G.cur_time - dp->d_recv_time);
+}
+
+static double
+root_distance(peer_t *p)
+{
+ /* 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 * (G.cur_time - p->lastpkt_recv_time)
+ + p->filter_jitter;
+}
+
+static void
+set_next(peer_t *p, unsigned t)
+{
+ p->next_action_time = G.cur_time + t;
+}
+
+/*
+ * Peer clock filter and its helpers
+ */
+static void
+filter_datapoints(peer_t *p)
+{
+ int i, idx;
+ double sum, wavg;
+ datapoint_t *fdp;
+
+#if 0
+/* Simulations have shown that use of *averaged* offset for p->filter_offset
+ * is in fact worse than simply using last received one: with large poll intervals
+ * (>= 2048) averaging code uses offset values which are outdated by hours,
+ * and time/frequency correction goes totally wrong when fed essentially bogus offsets.
+ */
+ int got_newest;
+ double minoff, maxoff, w;
+ double x = x; /* for compiler */
+ double oldest_off = oldest_off;
+ double oldest_age = oldest_age;
+ double newest_off = newest_off;
+ double newest_age = newest_age;
+
+ fdp = p->filter_datapoint;
+
+ minoff = maxoff = fdp[0].d_offset;
+ for (i = 1; i < NUM_DATAPOINTS; i++) {
+ if (minoff > fdp[i].d_offset)
+ minoff = fdp[i].d_offset;
+ if (maxoff < fdp[i].d_offset)
+ maxoff = fdp[i].d_offset;
+ }
+
+ idx = p->datapoint_idx; /* most recent datapoint's index */
+ /* 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
+ */
+ got_newest = 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,
+ fdp[idx].d_offset,
+ fdp[idx].d_dispersion, dispersion(&fdp[idx]),
+ G.cur_time - fdp[idx].d_recv_time,
+ (minoff == fdp[idx].d_offset || maxoff == fdp[idx].d_offset)
+ ? " (outlier by offset)" : ""
+ );
+ }
+
+ sum += dispersion(&fdp[idx]) / (2 << i);
+
+ if (minoff == fdp[idx].d_offset) {
+ minoff -= 1; /* so that we don't match it ever again */
+ } else
+ if (maxoff == fdp[idx].d_offset) {
+ maxoff += 1;
+ } else {
+ oldest_off = fdp[idx].d_offset;
+ oldest_age = G.cur_time - fdp[idx].d_recv_time;
+ if (!got_newest) {
+ got_newest = 1;
+ newest_off = oldest_off;
+ newest_age = oldest_age;
+ }
+ x = oldest_off * w;
+ wavg += x;
+ w /= 2;
+ }
+
+ idx = (idx - 1) & (NUM_DATAPOINTS - 1);
+ }
+ p->filter_dispersion = sum;
+ wavg += x; /* add another older6/64 to form older6/32 */
+ /* Fix systematic underestimation with large poll intervals.
+ * Imagine that we still have a bit of uncorrected drift,
+ * and poll interval is big (say, 100 sec). Offsets form a progression:
+ * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
+ * The algorithm above drops 0.0 and 0.7 as outliers,
+ * and then we have this estimation, ~25% off from 0.7:
+ * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
+ */
+ x = oldest_age - newest_age;
+ if (x != 0) {
+ x = newest_age / x; /* in above example, 100 / (600 - 100) */
+ if (x < 1) { /* paranoia check */
+ x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
+ wavg += x;
+ }
+ }
+ p->filter_offset = wavg;
+
+#else
+
+ fdp = p->filter_datapoint;
+ idx = p->datapoint_idx; /* most recent datapoint's index */
+
+ /* filter_offset: simply use the most recent value */
+ p->filter_offset = fdp[idx].d_offset;
+
+ /* n-1
+ * --- dispersion(i)
+ * filter_dispersion = \ -------------
+ * / (i+1)
+ * --- 2
+ * i=0
+ */
+ wavg = 0;
+ sum = 0;
+ for (i = 0; i < NUM_DATAPOINTS; i++) {
+ sum += dispersion(&fdp[idx]) / (2 << i);
+ wavg += fdp[idx].d_offset;
+ idx = (idx - 1) & (NUM_DATAPOINTS - 1);
+ }
+ wavg /= NUM_DATAPOINTS;
+ p->filter_dispersion = sum;
+#endif
+
+ /* +----- -----+ ^ 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 - fdp[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 offset)
+{
+ int i;
+ bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
+
+ for (i = 0; i < NUM_DATAPOINTS; i++) {
+ if (small_ofs) {
+ p->filter_datapoint[i].d_recv_time += offset;
+ if (p->filter_datapoint[i].d_offset != 0) {
+ p->filter_datapoint[i].d_offset -= offset;
+ //bb_error_msg("p->filter_datapoint[%d].d_offset %f -> %f",
+ // i,
+ // p->filter_datapoint[i].d_offset + offset,
+ // p->filter_datapoint[i].d_offset);
+ }
+ } else {
+ p->filter_datapoint[i].d_recv_time = G.cur_time;
+ p->filter_datapoint[i].d_offset = 0;
+ p->filter_datapoint[i].d_dispersion = MAXDISP;
+ }
+ }
+ if (small_ofs) {
+ p->lastpkt_recv_time += offset;
+ } else {
+ p->reachable_bits = 0;
+ p->lastpkt_recv_time = G.cur_time;
+ }
+ filter_datapoints(p); /* recalc p->filter_xxx */
+ 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 = G.cur_time; /* = set_next(p, 0); */
+ reset_peer_stats(p, 16 * STEP_THRESHOLD);
+
+ 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 void
+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);
+ }
+
+ /* Emit message _before_ attempted send. Think of a very short
+ * roundtrip networks: we need to go back to recv loop ASAP,
+ * to reduce delay. Printing messages after send works against that.
+ */
+ VERB1 bb_error_msg("sending query to %s", p->p_dotted);
+
+ /*
+ * 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;
+ }
+
+ p->reachable_bits <<= 1;
+ set_next(p, RESPONSE_INTERVAL);
+}
+
+
+/* Note that there is no provision to prevent several run_scripts
+ * to be done in quick succession. In fact, it happens rather often
+ * if initial syncronization results in a step.
+ * You will see "step" and then "stratum" script runs, sometimes
+ * as close as only 0.002 seconds apart.
+ * Script should be ready to deal with this.
+ */
+static void run_script(const char *action, double offset)
+{
+ char *argv[3];
+ char *env1, *env2, *env3, *env4;
+
+ if (!G.script_name)
+ return;
+
+ argv[0] = (char*) G.script_name;
+ argv[1] = (char*) action;
+ argv[2] = NULL;
+
+ VERB1 bb_error_msg("executing '%s %s'", G.script_name, action);
+
+ env1 = xasprintf("%s=%u", "stratum", G.stratum);
+ putenv(env1);
+ env2 = xasprintf("%s=%ld", "freq_drift_ppm", G.kernel_freq_drift);
+ putenv(env2);
+ env3 = xasprintf("%s=%u", "poll_interval", 1 << G.poll_exp);
+ putenv(env3);
+ env4 = xasprintf("%s=%f", "offset", offset);
+ putenv(env4);
+ /* Other items of potential interest: selected peer,
+ * rootdelay, reftime, rootdisp, refid, ntp_status,
+ * last_update_offset, last_update_recv_time, discipline_jitter,
+ * how many peers have reachable_bits = 0?
+ */
+
+ /* Don't want to wait: it may run hwclock --systohc, and that
+ * may take some time (seconds): */
+ /*spawn_and_wait(argv);*/
+ spawn(argv);
+
+ unsetenv("stratum");
+ unsetenv("freq_drift_ppm");
+ unsetenv("poll_interval");
+ unsetenv("offset");
+ free(env1);
+ free(env2);
+ free(env3);
+ free(env4);
+
+ G.last_script_run = G.cur_time;
+}
+
+static NOINLINE void
+step_time(double offset)
+{
+ llist_t *item;
+ double dtime;
+ struct timeval tvc, tvn;
+ char buf[sizeof("yyyy-mm-dd hh:mm:ss") + /*paranoia:*/ 4];
+ time_t tval;
+
+ gettimeofday(&tvc, NULL); /* never fails */
+ dtime = tvc.tv_sec + (1.0e-6 * tvc.tv_usec) + offset;
+ d_to_tv(dtime, &tvn);
+ if (settimeofday(&tvn, NULL) == -1)
+ bb_perror_msg_and_die("settimeofday");
+
+ VERB2 {
+ tval = tvc.tv_sec;
+ strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
+ bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
+ }
+ tval = tvn.tv_sec;
+ strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
+ bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
+
+ /* Correct various fields which contain time-relative values: */
+
+ /* Globals: */
+ G.cur_time += offset;
+ G.last_update_recv_time += offset;
+ G.last_script_run += offset;
+
+ /* p->lastpkt_recv_time, p->next_action_time and such: */
+ for (item = G.ntp_peers; item != NULL; item = item->link) {
+ peer_t *pp = (peer_t *) item->data;
+ reset_peer_stats(pp, offset);
+ //bb_error_msg("offset:%+f pp->next_action_time:%f -> %f",
+ // offset, pp->next_action_time, pp->next_action_time + offset);
+ pp->next_action_time += offset;
+ if (pp->p_fd >= 0) {
+ /* We wait for reply from this peer too.
+ * But due to step we are doing, reply's data is no longer
+ * useful (in fact, it'll be bogus). Stop waiting for it.
+ */
+ close(pp->p_fd);
+ pp->p_fd = -1;
+ set_next(pp, RETRY_INTERVAL);
+ }
+ }
+}
+
+
+/*
+ * Selection and clustering, and their helpers
+ */
+typedef struct {
+ peer_t *p;
+ int type;
+ double edge;
+ double opt_rd; /* optimization */
+} 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->reachable_bits & (p->reachable_bits-1)) == 0) {
+ /* One or zero bits in reachable_bits */
+ VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
+ return 0;
+ }
+#if 0 /* we filter out such packets earlier */
+ if ((p->lastpkt_status & 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;
+ }
+#endif
+ /* rd is root_distance(p) */
+ 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(void)
+{
+ peer_t *p;
+ 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;
+ if (G.initial_poll_complete) while (item != NULL) {
+ double rd, offset;
+
+ p = (peer_t *) item->data;
+ rd = root_distance(p);
+ 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;
+ point[num_points].opt_rd = rd;
+ num_points++;
+ point[num_points].p = p;
+ point[num_points].type = 0;
+ point[num_points].edge = offset;
+ point[num_points].opt_rd = rd;
+ num_points++;
+ point[num_points].p = p;
+ point[num_points].type = 1;
+ point[num_points].edge = offset + rd;
+ point[num_points].opt_rd = 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;
+ }
+//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++) {
+ if (point[i].edge < low || point[i].edge > high)
+ continue;
+ p = point[i].p;
+ survivor[num_survivors].p = p;
+ /* x.opt_rd == root_distance(p); */
+ survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + point[i].opt_rd;
+ 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) {
+ VERB3 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;
+
+ 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;
+ 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 / num_survivors);
+ 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++;
+ }
+ }
+
+ if (0) {
+ /* Combine the offsets of the clustering algorithm survivors
+ * using a weighted average with weight determined by the root
+ * distance. Compute the selection jitter as the weighted RMS
+ * difference between the first survivor and the remaining
+ * survivors. In some cases the inherent clock jitter can be
+ * reduced by not using this algorithm, especially when frequent
+ * clockhopping is involved. bbox: thus we don't do it.
+ */
+ double x, y, z, w;
+ y = z = w = 0;
+ for (i = 0; i < num_survivors; i++) {
+ p = survivor[i].p;
+ x = root_distance(p);
+ y += 1 / x;
+ z += p->filter_offset / x;
+ w += SQUARE(p->filter_offset - survivor[0].p->filter_offset) / x;
+ }
+ //G.cluster_offset = z / y;
+ //G.cluster_jitter = SQRT(w / y);
+ }
+
+ /* 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.
+ */
+ p = survivor[0].p;
+ if (G.last_update_peer
+ && G.last_update_peer->lastpkt_stratum <= p->lastpkt_stratum
+ ) {
+ /* Starting from 1 is ok here */
+ for (i = 1; i < num_survivors; i++) {
+ if (G.last_update_peer == survivor[i].p) {
+ VERB4 bb_error_msg("keeping old synced peer");
+ p = G.last_update_peer;
+ goto keep_old;
+ }
+ }
+ }
+ G.last_update_peer = p;
+ keep_old:
+ VERB3 bb_error_msg("selected peer %s filter_offset:%+f age:%f",
+ p->p_dotted,
+ p->filter_offset,
+ G.cur_time - p->lastpkt_recv_time
+ );
+ return 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 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;
+}
+/* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
+static NOINLINE int
+update_local_clock(peer_t *p)
+{
+ int rc;
+ struct timex tmx;
+ /* Note: can use G.cluster_offset instead: */
+ double offset = p->filter_offset;
+ double recv_time = p->lastpkt_recv_time;
+ double abs_offset;
+#if !USING_KERNEL_PLL_LOOP
+ double freq_drift;
+#endif
+ double since_last_update;
+ double etemp, dtemp;
+
+ abs_offset = fabs(offset);
+
+#if 0
+ /* If needed, -S script can do it by looking at $offset
+ * env var and killing parent */
+ /* 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);
+ }
+#endif
+
+ /* 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;
+#if !USING_KERNEL_PLL_LOOP
+ freq_drift = 0;
+#endif
+#if USING_INITIAL_FREQ_ESTIMATION
+ 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" */
+ }
+# if !USING_KERNEL_PLL_LOOP
+ freq_drift = (offset - G.last_update_offset) / since_last_update;
+# endif
+ }
+#endif
+
+ /* There are two main regimes: when the
+ * offset exceeds the step threshold and when it does not.
+ */
+ if (abs_offset > STEP_THRESHOLD) {
+ 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;
+
+ run_script("step", offset);
+
+#if USING_INITIAL_FREQ_ESTIMATION
+ if (G.discipline_state == STATE_NSET) {
+ set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
+ return 1; /* "ok to increase poll interval" */
+ }
+#endif
+ abs_offset = offset = 0;
+ set_new_values(STATE_SYNC, offset, recv_time);
+
+ } else { /* abs_offset <= STEP_THRESHOLD */
+
+ if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
+ VERB3 bb_error_msg("small offset:%+f, disabling burst mode", offset);
+ G.polladj_count = 0;
+ 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(offset - G.last_update_offset);
+ G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
+
+ 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);
+ }
+#if USING_INITIAL_FREQ_ESTIMATION
+ /* 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);
+#else
+ set_new_values(STATE_SYNC, offset, recv_time);
+#endif
+ VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
+ return 0; /* "leave poll interval as is" */
+
+#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
+
+#if USING_INITIAL_FREQ_ESTIMATION
+ 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;
+#endif
+
+ default:
+#if !USING_KERNEL_PLL_LOOP
+ /* 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);
+#endif
+ set_new_values(STATE_SYNC, offset, recv_time);
+ break;
+ }
+ if (G.stratum != p->lastpkt_stratum + 1) {
+ G.stratum = p->lastpkt_stratum + 1;
+ run_script("stratum", offset);
+ }
+ }
+
+ if (G.discipline_jitter < G_precision_sec)
+ G.discipline_jitter = G_precision_sec;
+ G.offset_to_jitter_ratio = abs_offset / G.discipline_jitter;
+
+ G.reftime = G.cur_time;
+ G.ntp_status = p->lastpkt_status;
+ G.refid = p->lastpkt_refid;
+ G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
+ dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(G.cluster_jitter));
+ dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (G.cur_time - 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 offset are set
+ * to values suitable for adjtimex.
+ */
+#if !USING_KERNEL_PLL_LOOP
+ /* 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(MAXDRIFT, dtemp), -MAXDRIFT);
+ 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);
+#endif
+ VERB3 {
+ memset(&tmx, 0, sizeof(tmx));
+ if (adjtimex(&tmx) < 0)
+ bb_perror_msg_and_die("adjtimex");
+ bb_error_msg("p adjtimex freq:%ld offset:%+ld status:0x%x tc:%ld",
+ tmx.freq, tmx.offset, tmx.status, tmx.constant);
+ }
+
+ memset(&tmx, 0, sizeof(tmx));
+#if 0
+//doesn't work, offset remains 0 (!) in kernel:
+//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;
+#endif
+ tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
+ tmx.offset = (offset * 1000000); /* usec */
+ tmx.status = STA_PLL;
+ if (G.ntp_status & LI_PLUSSEC)
+ tmx.status |= STA_INS;
+ if (G.ntp_status & LI_MINUSSEC)
+ tmx.status |= STA_DEL;
+
+ tmx.constant = G.poll_exp - 4;
+ /* EXPERIMENTAL.
+ * The below if statement should be unnecessary, but...
+ * It looks like Linux kernel's PLL is far too gentle in changing
+ * tmx.freq in response to clock offset. Offset keeps growing
+ * and eventually we fall back to smaller poll intervals.
+ * We can make correction more agressive (about x2) by supplying
+ * PLL time constant which is one less than the real one.
+ * To be on a safe side, let's do it only if offset is significantly
+ * larger than jitter.
+ */
+ if (tmx.constant > 0 && G.offset_to_jitter_ratio >= TIMECONST_HACK_GATE)
+ tmx.constant--;
+
+ //tmx.esterror = (uint32_t)(clock_jitter * 1e6);
+ //tmx.maxerror = (uint32_t)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
+ rc = adjtimex(&tmx);
+ if (rc < 0)
+ bb_perror_msg_and_die("adjtimex");
+ /* NB: here kernel returns constant == G.poll_exp, not == G.poll_exp - 4.
+ * Not sure why. Perhaps it is normal.
+ */
+ VERB3 bb_error_msg("adjtimex:%d freq:%ld offset:%+ld status:0x%x",
+ rc, tmx.freq, tmx.offset, tmx.status);
+ G.kernel_freq_drift = tmx.freq / 65536;
+ VERB2 bb_error_msg("update from:%s offset:%+f jitter:%f clock drift:%+.3fppm tc:%d",
+ p->p_dotted, offset, G.discipline_jitter, (double)tmx.freq / 65536, (int)tmx.constant);
+
+ 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)
+{
+ unsigned interval, r;
+ exponent = G.poll_exp + exponent;
+ if (exponent < 0)
+ exponent = 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 NOINLINE 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?
+ interval = retry_interval();
+ goto set_next_and_ret;
+ }
+ xfunc_die();
+ }
+
+ if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
+ bb_error_msg("malformed packet received from %s", p->p_dotted);
+ return;
+ }
+
+ 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
+ ) {
+ /* Somebody else's packet */
+ return;
+ }
+
+ /* 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;
+
+ 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: peer is unsynced, next query in %us", p->p_dotted, interval);
+ goto set_next_and_ret;
+ }
+
+// /* 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_status = msg.m_status;
+ p->lastpkt_stratum = msg.m_stratum;
+ 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 = G.cur_time;
+
+ 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->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);
+ if (p->lastpkt_delay < G_precision_sec)
+ p->lastpkt_delay = G_precision_sec;
+ datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
+ if (!p->reachable_bits) {
+ /* 1st datapoint ever - replicate offset in every element */
+ int i;
+ for (i = 0; i < NUM_DATAPOINTS; i++) {
+ p->filter_datapoint[i].d_offset = datapoint->d_offset;
+ }
+ }
+
+ p->reachable_bits |= 1;
+ if ((MAX_VERBOSE && G.verbose) || (option_mask32 & OPT_w)) {
+ bb_error_msg("reply from %s: offset:%+f delay:%f status:0x%02x strat:%d refid:0x%08x rootdelay:%f reach:0x%02x",
+ p->p_dotted,
+ datapoint->d_offset,
+ p->lastpkt_delay,
+ p->lastpkt_status,
+ p->lastpkt_stratum,
+ p->lastpkt_refid,
+ p->lastpkt_rootdelay,
+ p->reachable_bits
+ /* not shown: m_ppoll, m_precision_exp, m_rootdisp,
+ * m_reftime, m_orgtime, m_rectime, m_xmttime
+ */
+ );
+ }
+
+ /* Muck with statictics and update the clock */
+ filter_datapoints(p);
+ q = select_and_cluster();
+ rc = -1;
+ if (q) {
+ rc = 0;
+ if (!(option_mask32 & OPT_w)) {
+ rc = update_local_clock(q);
+ /* If drift is dangerously large, immediately
+ * drop poll interval one step down.
+ */
+ if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) {
+ VERB3 bb_error_msg("offset:%+f > POLLDOWN_OFFSET", q->filter_offset);
+ goto poll_down;
+ }
+ }
+ }
+ /* else: no peer selected, rc = -1: we want to poll more often */
+
+ 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.
+ */
+ if (rc > 0 && G.offset_to_jitter_ratio <= POLLADJ_GATE) {
+ /* was += G.poll_exp but it is a bit
+ * too optimistic for my taste at high poll_exp's */
+ G.polladj_count += MINPOLL;
+ 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.poll_exp >= BIGPOLL) {
+ poll_down:
+ G.polladj_count = 0;
+ if (G.poll_exp > MINPOLL) {
+ llist_t *item;
+
+ G.poll_exp--;
+ /* Correct p->next_action_time in each peer
+ * which waits for sending, so that they send earlier.
+ * Old pp->next_action_time are on the order
+ * of t + (1 << old_poll_exp) + small_random,
+ * we simply need to subtract ~half of that.
+ */
+ for (item = G.ntp_peers; item != NULL; item = item->link) {
+ peer_t *pp = (peer_t *) item->data;
+ if (pp->p_fd < 0)
+ pp->next_action_time -= (1 << 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_and_ret:
+ set_next(p, interval);
+}
+
+#if ENABLE_FEATURE_NTPD_SERVER
+static NOINLINE void
+recv_and_process_client_pkt(void /*int fd*/)
+{
+ ssize_t size;
+ //uint8_t version;
+ 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;
+ }
+
+ /*modify for HUB CVE-2016-6301*/
+ /* Respond only to client and symmetric active packets */
+ if ((msg.m_status & MODE_MASK) != MODE_CLIENT
+ && (msg.m_status & MODE_MASK) != MODE_SYM_ACT) {
+ 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.ntp_status & LI_MASK) : 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;
+ /* this time was obtained between poll() and recv() */
+ msg.m_rectime = d_to_lfp(G.cur_time);
+ msg.m_xmttime = d_to_lfp(gettime1900d()); /* this instant */
+ if (G.peer_cnt == 0) {
+ /* we have no peers: "stratum 1 server" mode. reftime = our own time */
+ G.reftime = G.cur_time;
+ }
+ 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 */
+ G.stratum = MAXSTRAT;
+ if (BURSTPOLL != 0)
+ G.poll_exp = BURSTPOLL; /* speeds up initial sync */
+ G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
+
+ /* Parse options */
+ peers = NULL;
+ opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
+ opts = getopt32(argv,
+ "nqNx" /* compat */
+ "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
+ "d" /* compat */
+ "46aAbgL", /* compat, ignored */
+ &peers, &G.script_name, &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;
+ if (peers) {
+ while (peers)
+ add_peers(llist_pop(&peers));
+ } else {
+ /* -l but no peers: "stratum 1 server" mode */
+ G.stratum = 1;
+ }
+ 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);
+
+ /* If network is up, syncronization occurs in ~10 seconds.
+ * We give "ntpd -q" 10 seconds to get first reply,
+ * then another 50 seconds to finish syncing.
+ *
+ * I tested ntpd 4.2.6p1 and apparently it never exits
+ * (will try forever), but it does not feel right.
+ * The goal of -q is to act like ntpdate: set time
+ * after a reasonably small period of polling, or fail.
+ */
+ if (opts & OPT_q) {
+ option_mask32 |= OPT_qq;
+ alarm(10);
+ }
+
+ bb_signals(0
+ | (1 << SIGTERM)
+ | (1 << SIGINT)
+ | (1 << SIGALRM)
+ , record_signo
+ );
+ bb_signals(0
+ | (1 << SIGPIPE)
+ | (1 << SIGCHLD)
+ , SIG_IGN
+ );
+}
+
+int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int ntpd_main(int argc UNUSED_PARAM, char **argv)
+{
+#undef G
+ struct globals G;
+ struct pollfd *pfd;
+ peer_t **idx2peer;
+ unsigned cnt;
+
+ memset(&G, 0, sizeof(G));
+ SET_PTR_TO_GLOBALS(&G);
+
+ ntp_init(argv);
+
+ /* If ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
+ cnt = G.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
+ idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
+ pfd = xzalloc(sizeof(pfd[0]) * cnt);
+
+ /* Countdown: we never sync before we sent INITIAL_SAMPLES+1
+ * packets to each peer.
+ * NB: if some peer is not responding, we may end up sending
+ * fewer packets to it and more to other peers.
+ * NB2: sync usually happens using INITIAL_SAMPLES packets,
+ * since last reply does not come back instantaneously.
+ */
+ cnt = G.peer_cnt * (INITIAL_SAMPLES + 1);
+
+ write_pidfile(CONFIG_PID_FILE_PATH "/ntpd.pid");
+
+ while (!bb_got_signal) {
+ llist_t *item;
+ unsigned i, j;
+ int nfds, timeout;
+ double nextaction;
+
+ /* Nothing between here and poll() blocks for any significant time */
+
+ nextaction = G.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 */
+ for (item = G.ntp_peers; item != NULL; item = item->link) {
+ peer_t *p = (peer_t *) item->data;
+
+ if (p->next_action_time <= G.cur_time) {
+ if (p->p_fd == -1) {
+ /* Time to send new req */
+ if (--cnt == 0) {
+ G.initial_poll_complete = 1;
+ }
+ send_query_to_peer(p);
+ } else {
+ /* Timed out waiting for reply */
+ close(p->p_fd);
+ p->p_fd = -1;
+ timeout = poll_interval(-2); /* -2: try a bit sooner */
+ bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
+ p->p_dotted, 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++;
+ }
+ }
+
+ timeout = nextaction - G.cur_time;
+ if (timeout < 0)
+ timeout = 0;
+ timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
+
+ /* Here we may block */
+ VERB2 {
+ if (i > (ENABLE_FEATURE_NTPD_SERVER && G_listen_fd != -1)) {
+ /* We wait for at least one reply.
+ * Poll for it, without wasting time for message.
+ * Since replies often come under 1 second, this also
+ * reduces clutter in logs.
+ */
+ nfds = poll(pfd, i, 1000);
+ if (nfds != 0)
+ goto did_poll;
+ if (--timeout <= 0)
+ goto did_poll;
+ }
+ bb_error_msg("poll:%us sockets:%u interval:%us", timeout, i, 1 << G.poll_exp);
+ }
+ nfds = poll(pfd, i, timeout * 1000);
+ did_poll:
+ gettime1900d(); /* sets G.cur_time */
+ if (nfds <= 0) {
+ if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
+ /* Useful for updating battery-backed RTC and such */
+ run_script("periodic", G.last_update_offset);
+ gettime1900d(); /* sets G.cur_time */
+ }
+ 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*/);
+ gettime1900d(); /* sets G.cur_time */
+ }
+ j = 1;
+ }
+#endif
+ for (; nfds != 0 && j < i; j++) {
+ if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
+ /*
+ * At init, alarm was set to 10 sec.
+ * Now we did get a reply.
+ * Increase timeout to 50 seconds to finish syncing.
+ */
+ if (option_mask32 & OPT_qq) {
+ option_mask32 &= ~OPT_qq;
+ alarm(50);
+ }
+ nfds--;
+ recv_and_process_peer_pkt(idx2peer[j]);
+ gettime1900d(); /* sets G.cur_time */
+ }
+ }
+ } /* while (!bb_got_signal) */
+
+ remove_pidfile(CONFIG_PID_FILE_PATH "/ntpd.pid");
+ 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