*
* Author: Adam Tkac <vonsch@gmail.com>
*
- * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ * 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
# error "Sorry, your kernel has to support IP_PKTINFO"
#endif
-#define INTERVAL_QUERY_NORMAL 30 /* sync to peers every n secs */
-#define INTERVAL_QUERY_PATHETIC 60
-#define INTERVAL_QUERY_AGRESSIVE 5
-#define TRUSTLEVEL_BADPEER 6 /* bad if *less than* TRUSTLEVEL_BADPEER */
-#define TRUSTLEVEL_PATHETIC 2
-#define TRUSTLEVEL_AGRESSIVE 8
-#define TRUSTLEVEL_MAX 10
-
-#define QSCALE_OFF_MIN 0.05
-#define QSCALE_OFF_MAX 0.50
-
-#define QUERYTIME_MAX 15 /* single query might take n secs max */
-#define OFFSET_ARRAY_SIZE 8
-#define SETTIME_MIN_OFFSET 180 /* min offset for settime at start */
-#define SETTIME_TIMEOUT 15 /* max seconds to wait with -s */
+/* Verbosity control (max level of -dddd options accepted).
+ * max 6 is very talkative (and bloated). 3 is non-bloated,
+ * production level setting.
+ */
+#define MAX_VERBOSE 3
-/* Style borrowed from NTP ref/tcpdump and updated for SNTPv4 (RFC2030). */
-/*
- * RFC Section 3
+/* High-level description of the algorithm:
*
- * 0 1 2 3
- * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- * | Integer Part |
- * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- * | Fraction Part |
- * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * 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.
*
- * 0 1 2 3
- * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- * | Integer Part | Fraction Part |
- * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-*/
-typedef struct {
- uint32_t int_partl;
- uint32_t fractionl;
-} l_fixedpt_t;
+ * (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.
+ *
+ * Made some changes to speed up re-syncing after our clock goes bad
+ * (tested with suspending my laptop):
+ * - if largish offset (>= STEP_THRESHOLD * 8 == 1 sec) is seen
+ * from a peer, schedule next query for this peer soon
+ * without drastically lowering poll interval for everybody.
+ * This makes us collect enough data for step much faster:
+ * e.g. at poll = 10 (1024 secs), step was done within 5 minutes
+ * after first reply which indicated that our clock is 14 seconds off.
+ * - on step, do not discard d_dispersion data of the existing datapoints,
+ * do not clear reachable_bits. This prevents discarding first ~8
+ * datapoints after the step.
+ */
+
+#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 */
+#define BAD_DELAY_GROWTH 4 /* drop packet if its delay grew by more than this */
+
+/* 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 we got largish offset from a peer, cap next query interval
+ * for this peer by this many seconds:
+ */
+#define BIGOFF_INTERVAL (1 << 6)
+/* 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
-typedef struct {
- uint16_t int_parts;
- uint16_t fractions;
-} s_fixedpt_t;
enum {
+ NTP_VERSION = 4,
+ NTP_MAXSTRATUM = 15,
+
NTP_DIGESTSIZE = 16,
NTP_MSGSIZE_NOAUTH = 48,
NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
-};
-
-typedef struct {
- uint8_t status; /* status of local clock and leap info */
- uint8_t stratum; /* stratum level */
- uint8_t ppoll; /* poll value */
- int8_t precision;
- s_fixedpt_t rootdelay;
- s_fixedpt_t dispersion;
- uint32_t refid;
- l_fixedpt_t reftime;
- l_fixedpt_t orgtime;
- l_fixedpt_t rectime;
- l_fixedpt_t xmttime;
- uint32_t keyid;
- uint8_t digest[NTP_DIGESTSIZE];
-} ntp_msg_t;
-
-typedef struct {
- int fd;
- ntp_msg_t msg;
- double xmttime;
-} ntp_query_t;
-
-enum {
- NTP_VERSION = 4,
- NTP_MAXSTRATUM = 15,
- /* Leap Second Codes (high order two bits) */
- 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 */
/* Status Masks */
- MODE_MASK = (7 << 0),
- VERSION_MASK = (7 << 3),
- VERSION_SHIFT = 3,
- LI_MASK = (3 << 6),
+ 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 */
+ 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 */
-enum client_state {
- STATE_NONE,
- STATE_QUERY_SENT,
- STATE_REPLY_RECEIVED,
-};
+#define NUM_DATAPOINTS 8
typedef struct {
- double rootdelay;
- double rootdispersion;
- double reftime;
- uint32_t refid;
- uint32_t refid4;
- uint8_t synced;
- uint8_t leap;
- int8_t precision;
- uint8_t poll;
- uint8_t stratum;
-} ntp_status_t;
+ uint32_t int_partl;
+ uint32_t fractionl;
+} l_fixedpt_t;
typedef struct {
- ntp_status_t status;
- double offset;
- double delay;
- double error;
- time_t rcvd;
- uint8_t good;
-} ntp_offset_t;
+ 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 {
-//TODO:
-// (1) store dotted addr str, to avoid constant translations
-// (2) periodically re-resolve DNS names
- len_and_sockaddr *lsa;
- ntp_query_t query;
- ntp_offset_t reply[OFFSET_ARRAY_SIZE];
- ntp_offset_t update;
- enum client_state state;
- time_t next;
- time_t deadline;
- uint8_t shift;
- uint8_t trustlevel;
-} ntp_peer_t;
+ 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_g = (1 << 1),
- OPT_q = (1 << 2),
- OPT_N = (1 << 3),
+ 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,
+ 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 {
- unsigned verbose;
+ 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;
+ 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
- unsigned peer_cnt;
- llist_t *ntp_peers;
- ntp_status_t status;
- uint32_t scale;
- uint8_t settime;
- uint8_t firstadj;
};
#define G (*ptr_to_globals)
-
static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
-static void
-set_next(ntp_peer_t *p, time_t t)
+#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)
+#define VERB6 if (MAX_VERBOSE >= 6 && G.verbose >= 6)
+
+
+static double LOG2D(int a)
{
- p->next = time(NULL) + t;
- p->deadline = 0;
+ if (a < 0)
+ return 1.0 / (1UL << -a);
+ return 1UL << a;
}
-
-static void
-add_peers(const char *s)
+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)
{
- ntp_peer_t *p;
+ 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.
+ */
- p = xzalloc(sizeof(*p));
-//TODO: big ntpd uses all IPs, not just 1st, do we need to mimic that?
- p->lsa = xhost2sockaddr(s, 123);
- p->query.fd = -1;
- p->query.msg.status = MODE_CLIENT | (NTP_VERSION << 3);
- if (STATE_NONE != 0)
- p->state = STATE_NONE;
- p->trustlevel = TRUSTLEVEL_PATHETIC;
- p->query.fd = -1;
- set_next(p, 0);
+ 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);
- llist_add_to(&G.ntp_peers, p);
- G.peer_cnt++;
+ /* This avoids needing libm, saves about 0.5k on x86-32 */
+ return my_SQRT(X);
}
static double
-gettime1900fp(void)
+gettime1900d(void)
{
struct timeval tv;
gettimeofday(&tv, NULL); /* never fails */
- return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970);
+ G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
+ return G.cur_time;
}
static void
ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
return ret;
}
-
static double
sfp_to_d(s_fixedpt_t sfp)
{
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)
lfp.fractionl = htonl(lfp.fractionl);
return lfp;
}
-
static s_fixedpt_t
d_to_sfp(double d)
{
}
#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_deadline(ntp_peer_t *p, time_t t)
+set_next(peer_t *p, unsigned t)
{
- p->deadline = time(NULL) + t;
- p->next = 0;
+ p->next_action_time = G.cur_time + t;
}
-static time_t
-error_interval(void)
+/*
+ * Peer clock filter and its helpers
+ */
+static void
+filter_datapoints(peer_t *p)
{
- time_t interval, r;
- interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN;
- r = (unsigned)random() % (unsigned long)(interval / 10);
- return (interval + r);
+ 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++) {
+ VERB5 {
+ 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;
+
+ VERB4 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;
+
+ /* Used to set p->filter_datapoint[i].d_dispersion = MAXDISP
+ * and clear reachable bits, but this proved to be too agressive:
+ * after step (tested with suspinding laptop for ~30 secs),
+ * this caused all previous data to be considered invalid,
+ * making us needing to collect full ~8 datapoins per peer
+ * after step in order to start trusting them.
+ * In turn, this was making poll interval decrease even after
+ * step was done. (Poll interval decreases already before step
+ * in this scenario, because we see large offsets and end up with
+ * no good peer to select).
+ */
+
+ 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 */
+ VERB6 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
-sendmsg_wrap(int fd,
+do_sendto(int fd,
const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
- ntp_msg_t *msg, ssize_t len)
+ msg_t *msg, ssize_t len)
{
ssize_t ret;
return 0;
}
-static int
-send_query_to_peer(ntp_peer_t *p)
+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->query.fd == -1) {
+ /* 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->lsa->u.sa.sa_family;
- //was: p->query.fd = xsocket(family, SOCK_DGRAM, 0);
- p->query.fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
+ 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->query.fd, thus later recv(p->query.fd)
+ * and remembered in p->p_fd, thus later recv(p->p_fd)
* receives only packets sent to this port.
*/
PROBE_LOCAL_ADDR
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
*
* 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();
+
+ /* Were doing it only if sendto worked, but
+ * loss of sync detection needs reachable_bits updated
+ * even if sending fails *locally*:
+ * "network is unreachable" because cable was pulled?
+ * We still need to declare "unsync" if this condition persists.
+ */
+ p->reachable_bits <<= 1;
- p->query.msg.xmttime.int_partl = random();
- p->query.msg.xmttime.fractionl = random();
- p->query.xmttime = gettime1900fp();
+ 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;
+ /*
+ * We know that we sent nothing.
+ * We can retry *soon* without fearing
+ * that we are flooding the peer.
+ */
+ set_next(p, RETRY_INTERVAL);
+ return;
+ }
- if (sendmsg_wrap(p->query.fd, /*from:*/ NULL, /*to:*/ &p->lsa->u.sa, /*addrlen:*/ p->lsa->len,
- &p->query.msg, NTP_MSGSIZE_NOAUTH) == -1) {
- set_next(p, INTERVAL_QUERY_PATHETIC);
- return -1;
+ set_next(p, RESPONSE_INTERVAL);
+}
+
+
+/* Note that there is no provision to prevent several run_scripts
+ * to be started 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;
+
+ G.last_script_run = G.cur_time;
+
+ 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);
+}
+
+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_YYYYMMDDHHMMSS(buf, sizeof(buf), &tval);
+ bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
}
+ tval = tvn.tv_sec;
+ strftime_YYYYMMDDHHMMSS(buf, sizeof(buf), &tval);
+ bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
- p->state = STATE_QUERY_SENT;
- set_deadline(p, QUERYTIME_MAX);
+ /* Correct various fields which contain time-relative values: */
- return 0;
+ /* 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
-offset_compare(const void *aa, const void *bb)
+compare_point_edge(const void *aa, const void *bb)
{
- const ntp_peer_t *const *a = aa;
- const ntp_peer_t *const *b = bb;
- if ((*a)->update.offset < (*b)->update.offset)
+ const point_t *a = aa;
+ const point_t *b = bb;
+ if (a->edge < b->edge) {
return -1;
- return ((*a)->update.offset > (*b)->update.offset);
+ }
+ return (a->edge > b->edge);
}
-
-static uint32_t
-updated_scale(double offset)
+typedef struct {
+ peer_t *p;
+ double metric;
+} survivor_t;
+static int
+compare_survivor_metric(const void *aa, const void *bb)
{
- if (offset < 0)
- offset = -offset;
- if (offset > QSCALE_OFF_MAX)
- return 1;
- if (offset < QSCALE_OFF_MIN)
- return QSCALE_OFF_MAX / QSCALE_OFF_MIN;
- return QSCALE_OFF_MAX / offset;
+ const survivor_t *a = aa;
+ const survivor_t *b = bb;
+ if (a->metric < b->metric) {
+ return -1;
+ }
+ return (a->metric > b->metric);
}
-
-static void
-adjtime_wrap(void)
+static int
+fit(peer_t *p, double rd)
{
- ntp_peer_t *p;
- unsigned offset_cnt;
- unsigned middle;
- int i = 0;
- ntp_peer_t **peers;
- double offset_median;
- llist_t *item;
- len_and_sockaddr *lsa;
- struct timeval tv, olddelta;
-
- offset_cnt = 0;
- for (item = G.ntp_peers; item != NULL; item = item->link) {
- p = (ntp_peer_t *) item->data;
- if (p->trustlevel < TRUSTLEVEL_BADPEER)
+ if ((p->reachable_bits & (p->reachable_bits-1)) == 0) {
+ /* One or zero bits in reachable_bits */
+ VERB4 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
+ ) {
+ VERB4 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)) {
+ VERB4 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;
- if (!p->update.good)
- return;
- offset_cnt++;
+ }
+
+ VERB5 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%s", ", 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("falsetickers:%d, candidates:%d%s",
+ num_falsetickers, num_candidates,
+ ", no peer selected");
+ return NULL;
+ }
+ }
+ VERB4 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
+ low, high, num_candidates, num_falsetickers);
- if (offset_cnt == 0)
- goto clear_good;
+ /* Clustering */
- peers = xzalloc(sizeof(peers[0]) * offset_cnt);
- for (item = G.ntp_peers; item != NULL; item = item->link) {
- p = (ntp_peer_t *) item->data;
- if (p->trustlevel < TRUSTLEVEL_BADPEER)
+ /* 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;
- peers[i++] = p;
+ 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;
+ VERB5 bb_error_msg("survivor[%d] metric:%f peer:%s",
+ num_survivors, survivor[num_survivors].metric, p->p_dotted);
+ num_survivors++;
}
-
- qsort(peers, offset_cnt, sizeof(peers[0]), offset_compare);
-
- middle = offset_cnt / 2;
- if (middle != 0 && (offset_cnt & 1) == 0) {
- offset_median = (peers[middle-1]->update.offset + peers[middle]->update.offset) / 2;
- G.status.rootdelay = (peers[middle-1]->update.delay + peers[middle]->update.delay) / 2;
- G.status.stratum = MAX(peers[middle-1]->update.status.stratum, peers[middle]->update.status.stratum);
- } else {
- offset_median = peers[middle]->update.offset;
- G.status.rootdelay = peers[middle]->update.delay;
- G.status.stratum = peers[middle]->update.status.stratum;
+ /* 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("survivors:%d%s",
+ num_survivors,
+ ", no peer selected");
+ return NULL;
}
- G.status.leap = peers[middle]->update.status.leap;
- bb_info_msg("adjusting local clock by %fs", offset_median);
+//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);
- d_to_tv(offset_median, &tv);
- if (adjtime(&tv, &olddelta) == -1)
- bb_error_msg("adjtime failed");
- else if (!G.firstadj
- && olddelta.tv_sec == 0
- && olddelta.tv_usec == 0
- && !G.status.synced
- ) {
- bb_info_msg("clock synced");
- G.status.synced = 1;
- } else if (G.status.synced) {
- bb_info_msg("clock unsynced");
- G.status.synced = 0;
- }
+ /* 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) {
+ VERB4 bb_error_msg("num_survivors %d <= %d, not discarding more",
+ num_survivors, MIN_CLUSTERED);
+ break;
+ }
- G.firstadj = 0;
- G.status.reftime = gettime1900fp();
- G.status.stratum++; /* one more than selected peer */
- G.scale = updated_scale(offset_median);
+ /* 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;
- G.status.refid4 = peers[middle]->update.status.refid4;
+ p = survivor[i].p;
+ if (i == 0 || p->filter_jitter < min_jitter)
+ min_jitter = p->filter_jitter;
- lsa = peers[middle]->lsa;
- G.status.refid =
-#if ENABLE_FEATURE_IPV6
- lsa->u.sa.sa_family != AF_INET ?
- G.status.refid4 :
-#endif
- lsa->u.sin.sin_addr.s_addr;
+ 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;
+ }
+ VERB6 bb_error_msg("survivor %d selection_jitter^2:%f",
+ i, selection_jitter_sq);
+ }
+ max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
+ VERB5 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) {
+ VERB4 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
+ max_selection_jitter, min_jitter, num_survivors);
+ break;
+ }
- free(peers);
+ /* Delete survivor[max_idx] from the list
+ * and go around again.
+ */
+ VERB6 bb_error_msg("dropping survivor %d", max_idx);
+ num_survivors--;
+ while (max_idx < num_survivors) {
+ survivor[max_idx] = survivor[max_idx + 1];
+ max_idx++;
+ }
+ }
- clear_good:
- for (item = G.ntp_peers; item != NULL; item = item->link) {
- p = (ntp_peer_t *) item->data;
- p->update.good = 0;
+ 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) {
+ VERB5 bb_error_msg("keeping old synced peer");
+ p = G.last_update_peer;
+ goto keep_old;
+ }
+ }
+ }
+ G.last_update_peer = p;
+ keep_old:
+ VERB4 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
-settime(double offset)
+set_new_values(int disc_state, double offset, double recv_time)
{
- ntp_peer_t *p;
- llist_t *item;
- struct timeval tv, curtime;
- char buf[80];
- time_t tval;
-
- if (!G.settime)
- goto bail;
-
- G.settime = 0;
+ /* 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.
+ */
+ VERB4 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;
- /* if the offset is small, don't call settimeofday */
- if (offset < SETTIME_MIN_OFFSET && offset > -SETTIME_MIN_OFFSET)
- goto bail;
+ abs_offset = fabs(offset);
- gettimeofday(&curtime, NULL); /* never fails */
+#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
- d_to_tv(offset, &tv);
- curtime.tv_usec += tv.tv_usec + 1000000;
- curtime.tv_sec += tv.tv_sec - 1 + (curtime.tv_usec / 1000000);
- curtime.tv_usec %= 1000000;
+ /* 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("update from %s: same or older datapoint, not using it",
+ p->p_dotted);
+ return 0; /* "leave poll interval as is" */
+ }
- if (settimeofday(&curtime, NULL) == -1) {
- bb_error_msg("settimeofday");
- goto bail;
+ /* 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) {
+ VERB4 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
- tval = curtime.tv_sec;
- strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
+ /* There are two main regimes: when the
+ * offset exceeds the step threshold and when it does not.
+ */
+ if (abs_offset > STEP_THRESHOLD) {
+#if 0
+ double remains;
+
+// This "spike state" seems to be useless, peer selection already drops
+// occassional "bad" datapoints. If we are here, there were _many_
+// large offsets. When a few first large offsets are seen,
+// we end up in "no valid datapoints, no peer selected" state.
+// Only when enough of them are seen (which means it's not a fluke),
+// we end up here. Looks like _our_ clock is off.
+ switch (G.discipline_state) {
+ case STATE_SYNC:
+ /* The first outlyer: ignore it, switch to SPIK state */
+ VERB3 bb_error_msg("update from %s: offset:%+f, spike%s",
+ p->p_dotted, 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.
+ */
+ remains = WATCH_THRESHOLD - since_last_update;
+ if (remains > 0) {
+ VERB3 bb_error_msg("update from %s: offset:%+f, spike%s",
+ p->p_dotted, offset,
+ ", datapoint ignored");
+ return -1; /* "decrease poll interval" */
+ }
+ /* fall through: we need to step */
+ } /* switch */
+#endif
- /* Do we want to print message below to system log when daemonized? */
- bb_info_msg("set local clock to %s (offset %fs)", buf, offset);
+ /* 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.
+ */
+ VERB4 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);
+ }
- for (item = G.ntp_peers; item != NULL; item = item->link) {
- p = (ntp_peer_t *) item->data;
- if (p->next)
- p->next -= offset;
- if (p->deadline)
- p->deadline -= offset;
- }
+ G.polladj_count = 0;
+ G.poll_exp = MINPOLL;
+ G.stratum = MAXSTRAT;
- bail:
- if (option_mask32 & OPT_q)
- exit(0);
-}
+ run_script("step", offset);
-static void
-update_peer_data(ntp_peer_t *p)
-{
- int i, best = 0, good = 0;
+ recv_time += offset;
- /*
- * clock filter
- * find the offset which arrived with the lowest delay
- * use that as the peer update
- * invalidate it and all older ones
- */
+#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 */
- for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++) {
- if (p->reply[i].good) {
- good++;
- best = i;
+ if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
+ VERB4 bb_error_msg("small offset:%+f, disabling burst mode", offset);
+ G.polladj_count = 0;
+ G.poll_exp = MINPOLL;
}
- }
- for (; i < OFFSET_ARRAY_SIZE; i++) {
- if (p->reply[i].good) {
- good++;
- if (p->reply[i].delay < p->reply[best].delay)
- best = i;
+ /* 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
+ VERB4 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 (good < 8)
- return;
+ 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;
+ VERB4 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);
+
+ VERB4 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
+ VERB4 {
+ 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);
+ }
- memcpy(&p->update, &p->reply[best], sizeof(p->update));
- adjtime_wrap();
+ 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.
+ */
+ VERB4 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);
- for (i = 0; i < OFFSET_ARRAY_SIZE; i++)
- if (p->reply[i].rcvd <= p->reply[best].rcvd)
- p->reply[i].good = 0;
+ return 1; /* "ok to increase poll interval" */
}
-static time_t
-scale_interval(time_t requested)
+
+/*
+ * We've got a new reply packet from a peer, process it
+ * (helpers first)
+ */
+static unsigned
+retry_interval(void)
{
- time_t interval, r;
- interval = requested * G.scale;
- r = (unsigned)random() % (unsigned long)(MAX(5, interval / 10));
- return (interval + r);
+ /* Local problem, want to retry soon */
+ unsigned interval, r;
+ interval = RETRY_INTERVAL;
+ r = random();
+ interval += r % (unsigned)(RETRY_INTERVAL / 4);
+ VERB4 bb_error_msg("chose retry interval:%u", interval);
+ return interval;
}
-
-static void
-recv_and_process_peer_pkt(ntp_peer_t *p)
+static unsigned
+poll_interval(int exponent)
{
- char *addr;
- ssize_t size;
- ntp_msg_t msg;
- double T1, T2, T3, T4;
- time_t interval;
- ntp_offset_t *offset;
+ 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 */
+ VERB4 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;
+ double dv, offset;
+ unsigned interval;
+ datapoint_t *datapoint;
+ peer_t *q;
- addr = xmalloc_sockaddr2dotted_noport(&p->lsa->u.sa);
+ offset = 0;
/* 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->query.fd, &msg, sizeof(msg), MSG_DONTWAIT);
+ size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
if (size == -1) {
- bb_perror_msg("recv(%s) error", addr);
+ 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, error_interval());
- goto bail;
+ interval = retry_interval();
+ goto set_next_and_ret;
}
xfunc_die();
}
- T4 = gettime1900fp();
-
if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
- bb_error_msg("malformed packet received from %s", addr);
- goto bail;
+ bb_error_msg("malformed packet received from %s", p->p_dotted);
+ return;
}
- if (msg.orgtime.int_partl != p->query.msg.xmttime.int_partl
- || msg.orgtime.fractionl != p->query.msg.xmttime.fractionl
+ 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;
+ /* Somebody else's packet */
+ return;
}
- if ((msg.status & LI_ALARM) == LI_ALARM
- || msg.stratum == 0
- || msg.stratum > NTP_MAXSTRATUM
+ /* 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
) {
- interval = error_interval();
- bb_info_msg("reply from %s: not synced, next query %ds", addr, (int) interval);
- goto bail;
+// 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
+ bb_error_msg("reply from %s: peer is unsynced", p->p_dotted);
+ goto pick_normal_interval;
}
+// /* 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
+ * 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 d and local clock offset t are defined as
+ * The roundtrip delay and local clock offset are defined as
*
- * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2.
+ * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
*/
-
- T1 = p->query.xmttime;
- T2 = lfp_to_d(msg.rectime);
- T3 = lfp_to_d(msg.xmttime);
-
- offset = &p->reply[p->shift];
-
- offset->offset = ((T2 - T1) + (T3 - T4)) / 2;
- offset->delay = (T4 - T1) - (T3 - T2);
- if (offset->delay < 0) {
- interval = error_interval();
- set_next(p, interval);
- bb_info_msg("reply from %s: negative delay %f", addr, p->reply[p->shift].delay);
- goto bail;
+ 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;
+ VERB6 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
+
+ /* 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.
+ */
+ dv = p->lastpkt_delay;
+ p->lastpkt_delay = (T4 - T1) - (T3 - T2);
+ if (p->lastpkt_delay < G_precision_sec)
+ p->lastpkt_delay = G_precision_sec;
+ /*
+ * If this packet's delay is much bigger than the last one,
+ * it's better to just ignore it than use its much less precise value.
+ */
+ if (p->reachable_bits && p->lastpkt_delay > dv * BAD_DELAY_GROWTH) {
+ bb_error_msg("reply from %s: delay %f is too high, ignoring", p->p_dotted, p->lastpkt_delay);
+ goto pick_normal_interval;
}
- offset->error = (T2 - T1) - (T3 - T4);
-// Can we use (T4 - OFFSET_1900_1970) instead of time(NULL)?
- offset->rcvd = time(NULL);
- offset->good = 1;
-
- offset->status.leap = (msg.status & LI_MASK);
- offset->status.precision = msg.precision;
- offset->status.rootdelay = sfp_to_d(msg.rootdelay);
- offset->status.rootdispersion = sfp_to_d(msg.dispersion);
- offset->status.refid = ntohl(msg.refid);
- offset->status.refid4 = msg.xmttime.fractionl;
- offset->status.reftime = lfp_to_d(msg.reftime);
- offset->status.poll = msg.ppoll;
- offset->status.stratum = msg.stratum;
-
- if (p->trustlevel < TRUSTLEVEL_PATHETIC)
- interval = scale_interval(INTERVAL_QUERY_PATHETIC);
- else if (p->trustlevel < TRUSTLEVEL_AGRESSIVE)
- interval = scale_interval(INTERVAL_QUERY_AGRESSIVE);
- else
- interval = scale_interval(INTERVAL_QUERY_NORMAL);
- set_next(p, interval);
- p->state = STATE_REPLY_RECEIVED;
-
- /* every received reply which we do not discard increases trust */
- if (p->trustlevel < TRUSTLEVEL_MAX) {
- p->trustlevel++;
- if (p->trustlevel == TRUSTLEVEL_BADPEER)
- bb_info_msg("peer %s now valid", addr);
+ 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 = offset = ((T2 - T1) + (T3 - T4)) / 2;
+ 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 = offset;
+ }
}
- bb_info_msg("reply from %s: offset %f delay %f, next query %ds", addr,
- offset->offset, offset->delay, (int) interval);
+ 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,
+ 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
+ */
+ );
+ }
- update_peer_data(p);
- settime(offset->offset);
+ /* 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) {
+ VERB4 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++;
+ VERB4 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
+ G.discipline_jitter, G.poll_exp);
+ }
+ } else {
+ VERB4 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);
+ }
+ VERB4 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
+ G.discipline_jitter, G.poll_exp);
+ }
+ } else {
+ VERB4 bb_error_msg("polladj: decr:%d", G.polladj_count);
+ }
+ }
+ }
- p->shift++;
- if (p->shift >= OFFSET_ARRAY_SIZE)
- p->shift = 0;
+ /* Decide when to send new query for this peer */
+ pick_normal_interval:
+ interval = poll_interval(0);
+ if (fabs(offset) >= STEP_THRESHOLD * 8 && interval > BIGOFF_INTERVAL) {
+ /* If we are synced, offsets are less than STEP_THRESHOLD,
+ * or at the very least not much larger than it.
+ * Now we see a largish one.
+ * Either this peer is feeling bad, or packet got corrupted,
+ * or _our_ clock is wrong now and _all_ peers will show similar
+ * largish offsets too.
+ * I observed this with laptop suspend stopping clock.
+ * In any case, it makes sense to make next request soonish:
+ * cases 1 and 2: get a better datapoint,
+ * case 3: allows to resync faster.
+ */
+ interval = BIGOFF_INTERVAL;
+ }
- bail:
- free(addr);
+ set_next_and_ret:
+ set_next(p, interval);
}
#if ENABLE_FEATURE_NTPD_SERVER
-static void
+static NOINLINE void
recv_and_process_client_pkt(void /*int fd*/)
{
ssize_t size;
- uint8_t version;
- double rectime;
+ //uint8_t version;
len_and_sockaddr *to;
struct sockaddr *from;
- ntp_msg_t msg;
+ msg_t msg;
uint8_t query_status;
- uint8_t query_ppoll;
l_fixedpt_t query_xmttime;
- to = get_sock_lsa(G.listen_fd);
+ 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);
+ 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_from_to");
+ bb_perror_msg_and_die("recv");
}
addr = xmalloc_sockaddr2dotted_noport(from);
- bb_error_msg("malformed packet received from %s", addr);
+ bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
free(addr);
goto bail;
}
- query_status = msg.status;
- query_ppoll = msg.ppoll;
- query_xmttime = msg.xmttime;
+ query_status = msg.m_status;
+ query_xmttime = msg.m_xmttime;
/* Build a reply packet */
memset(&msg, 0, sizeof(msg));
- msg.status = G.status.synced ? G.status.leap : LI_ALARM;
- msg.status |= (query_status & VERSION_MASK);
- msg.status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
- MODE_SERVER : MODE_SYM_PAS;
- msg.stratum = G.status.stratum;
- msg.ppoll = query_ppoll;
- msg.precision = G.status.precision;
- rectime = gettime1900fp();
- msg.xmttime = msg.rectime = d_to_lfp(rectime);
- msg.reftime = d_to_lfp(G.status.reftime);
- //msg.xmttime = d_to_lfp(gettime1900fp()); // = msg.rectime
- msg.orgtime = query_xmttime;
- msg.rootdelay = d_to_sfp(G.status.rootdelay);
- version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
- msg.refid = (version > (3 << VERSION_SHIFT)) ? G.status.refid4 : G.status.refid;
+ 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: */
- sendmsg_wrap(G.listen_fd,
+ do_sendto(G_listen_fd,
/*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
&msg, size);
llist_t *peers;
srandom(getpid());
- /* tzset(); - why? it's called automatically when needed, no? */
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::"; /* d: counter, p: list */
+ opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
opts = getopt32(argv,
- "ngqN" /* compat */
- "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
+ "nqNx" /* compat */
+ "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
"d" /* compat */
- "46aAbLx", /* compat, ignored */
- &peers, &G.verbose);
+ "46aAbgL", /* compat, ignored */
+ &peers, &G.script_name, &G.verbose);
if (!(opts & (OPT_p|OPT_l)))
bb_show_usage();
- if (opts & OPT_g)
- G.settime = 1;
- while (peers)
- add_peers(llist_pop(&peers));
+// 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;
+ 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));
+ 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);
- /* Set some globals */
- {
- 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.status.precision = prec;
+ /* 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);
}
- G.scale = 1;
- G.firstadj = 1;
- bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo);
- bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN);
+ 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)
{
- struct globals g;
+#undef G
+ struct globals G;
struct pollfd *pfd;
- ntp_peer_t **idx2peer;
+ peer_t **idx2peer;
+ unsigned cnt;
- memset(&g, 0, sizeof(g));
- SET_PTR_TO_GLOBALS(&g);
+ memset(&G, 0, sizeof(G));
+ SET_PTR_TO_GLOBALS(&G);
ntp_init(argv);
- {
- unsigned cnt = g.peer_cnt;
- /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
- idx2peer = xzalloc(sizeof(void *) * (cnt + ENABLE_FEATURE_NTPD_SERVER));
- pfd = xzalloc(sizeof(pfd[0]) * (cnt + ENABLE_FEATURE_NTPD_SERVER));
- }
+ /* 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;
- unsigned sent_cnt, trial_cnt;
int nfds, timeout;
- time_t cur_time, nextaction;
+ double nextaction;
/* Nothing between here and poll() blocks for any significant time */
- cur_time = time(NULL);
- nextaction = cur_time + 3600;
+ nextaction = G.cur_time + 3600;
i = 0;
#if ENABLE_FEATURE_NTPD_SERVER
- if (g.listen_fd != -1) {
- pfd[0].fd = g.listen_fd;
+ 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) {
- ntp_peer_t *p = (ntp_peer_t *) item->data;
-
- if (p->next != 0 && p->next <= cur_time) {
- /* Time to send new req */
- trial_cnt++;
- if (send_query_to_peer(p) == 0)
- sent_cnt++;
- }
- if (p->deadline != 0 && p->deadline <= cur_time) {
- /* Timed out waiting for reply */
- char *addr = xmalloc_sockaddr2dotted_noport(&p->lsa->u.sa);
-
- timeout = error_interval();
- bb_info_msg("no reply from %s received in time, "
- "next query %ds", addr, timeout);
- if (p->trustlevel >= TRUSTLEVEL_BADPEER) {
- p->trustlevel /= 2;
- if (p->trustlevel < TRUSTLEVEL_BADPEER)
- bb_info_msg("peer %s now invalid", addr);
+ 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);
}
- free(addr);
-
- set_next(p, timeout);
}
- if (p->next != 0 && p->next < nextaction)
- nextaction = p->next;
- if (p->deadline != 0 && p->deadline < nextaction)
- nextaction = p->deadline;
+ if (p->next_action_time < nextaction)
+ nextaction = p->next_action_time;
- if (p->state == STATE_QUERY_SENT) {
+ if (p->p_fd >= 0) {
/* Wait for reply from this peer */
- pfd[i].fd = p->query.fd;
+ 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)
- settime(0); /* no good peers, don't wait */
-
- timeout = nextaction - cur_time;
+ timeout = nextaction - G.cur_time;
if (timeout < 0)
timeout = 0;
+ timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
/* Here we may block */
- if (g.verbose)
- bb_error_msg("entering poll %u secs", timeout);
+ 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);
- if (nfds <= 0)
- continue;
+ did_poll:
+ gettime1900d(); /* sets G.cur_time */
+ if (nfds <= 0) {
+ if (!bb_got_signal /* poll wasn't interrupted by a signal */
+ && 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 */
+ }
+ goto check_unsync;
+ }
/* Process any received packets */
j = 0;
#if ENABLE_FEATURE_NTPD_SERVER
- if (g.listen_fd != -1) {
+ if (G.listen_fd != -1) {
if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
nfds--;
- recv_and_process_client_pkt(/*g.listen_fd*/);
+ 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 */
+ }
+ }
+
+ check_unsync:
+ if (G.ntp_peers && G.stratum != MAXSTRAT) {
+ for (item = G.ntp_peers; item != NULL; item = item->link) {
+ peer_t *p = (peer_t *) item->data;
+ if (p->reachable_bits)
+ goto have_reachable_peer;
}
+ /* No peer responded for last 8 packets, panic */
+ G.polladj_count = 0;
+ G.poll_exp = MINPOLL;
+ G.stratum = MAXSTRAT;
+ run_script("unsync", 0.0);
+ have_reachable_peer: ;
}
} /* 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
projects / platform / upstream / busybox.git / blobdiff