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busybox/networking/ntpd.c
Paul Marks b7841cf7b9 ntpd: fix incorrect m_status field in outgoing packets. Closes 5120 
When using busybox ntpd with an NTPv3 client and NTPv4 server (or vice
versa), the version numbers can be incorrectly ORed together, yielding
the bogus value of "NTPv7".  This makes ntpd unusable with clients
such as Chrony and Windows "Internet Time".

This patch avoids the version mangling, by copying only the Leap
Indicator bits from the server's status field.

Signed-off-by: Paul Marks <paul@pmarks.net>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2013-01-14 02:39:10 +01:00

2388 lines
74 KiB
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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;
}
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
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