0b3a38b9f5
function old new delta recv_and_process_peer_pkt 892 922 +30 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2490 lines
78 KiB
C
2490 lines
78 KiB
C
/*
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* NTP client/server, based on OpenNTPD 3.9p1
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*
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* Author: Adam Tkac <vonsch@gmail.com>
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*
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* Parts of OpenNTPD clock syncronization code is replaced by
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* code which is based on ntp-4.2.6, whuch carries the following
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* copyright notice:
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*
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***********************************************************************
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* *
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* Copyright (c) University of Delaware 1992-2009 *
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* *
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* Permission to use, copy, modify, and distribute this software and *
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* its documentation for any purpose with or without fee is hereby *
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* granted, provided that the above copyright notice appears in all *
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* copies and that both the copyright notice and this permission *
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* notice appear in supporting documentation, and that the name *
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* University of Delaware not be used in advertising or publicity *
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* pertaining to distribution of the software without specific, *
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* written prior permission. The University of Delaware makes no *
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* representations about the suitability this software for any *
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* purpose. It is provided "as is" without express or implied *
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* warranty. *
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* *
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***********************************************************************
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*/
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//usage:#define ntpd_trivial_usage
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//usage: "[-dnqNw"IF_FEATURE_NTPD_SERVER("l")"] [-S PROG] [-p PEER]..."
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//usage:#define ntpd_full_usage "\n\n"
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//usage: "NTP client/server\n"
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//usage: "\n -d Verbose"
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//usage: "\n -n Do not daemonize"
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//usage: "\n -q Quit after clock is set"
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//usage: "\n -N Run at high priority"
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//usage: "\n -w Do not set time (only query peers), implies -n"
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//usage: IF_FEATURE_NTPD_SERVER(
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//usage: "\n -l Run as server on port 123"
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//usage: )
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//usage: "\n -S PROG Run PROG after stepping time, stratum change, and every 11 mins"
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//usage: "\n -p PEER Obtain time from PEER (may be repeated)"
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#include "libbb.h"
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#include <math.h>
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#include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
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#include <sys/resource.h> /* setpriority */
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#include <sys/timex.h>
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#ifndef IPTOS_LOWDELAY
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# define IPTOS_LOWDELAY 0x10
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#endif
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#ifndef IP_PKTINFO
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# error "Sorry, your kernel has to support IP_PKTINFO"
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#endif
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/* Verbosity control (max level of -dddd options accepted).
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* max 6 is very talkative (and bloated). 3 is non-bloated,
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* production level setting.
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*/
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#define MAX_VERBOSE 3
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/* High-level description of the algorithm:
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*
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* We start running with very small poll_exp, BURSTPOLL,
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* in order to quickly accumulate INITIAL_SAMPLES datapoints
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* for each peer. Then, time is stepped if the offset is larger
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* than STEP_THRESHOLD, otherwise it isn't; anyway, we enlarge
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* poll_exp to MINPOLL and enter frequency measurement step:
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* we collect new datapoints but ignore them for WATCH_THRESHOLD
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* seconds. After WATCH_THRESHOLD seconds we look at accumulated
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* offset and estimate frequency drift.
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*
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* (frequency measurement step seems to not be strictly needed,
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* it is conditionally disabled with USING_INITIAL_FREQ_ESTIMATION
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* define set to 0)
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*
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* After this, we enter "steady state": we collect a datapoint,
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* we select the best peer, if this datapoint is not a new one
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* (IOW: if this datapoint isn't for selected peer), sleep
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* and collect another one; otherwise, use its offset to update
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* frequency drift, if offset is somewhat large, reduce poll_exp,
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* otherwise increase poll_exp.
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*
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* If offset is larger than STEP_THRESHOLD, which shouldn't normally
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* happen, we assume that something "bad" happened (computer
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* was hibernated, someone set totally wrong date, etc),
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* then the time is stepped, all datapoints are discarded,
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* and we go back to steady state.
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*
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* Made some changes to speed up re-syncing after our clock goes bad
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* (tested with suspending my laptop):
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* - if largish offset (>= STEP_THRESHOLD * 8 == 1 sec) is seen
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* from a peer, schedule next query for this peer soon
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* without drastically lowering poll interval for everybody.
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* This makes us collect enough data for step much faster:
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* e.g. at poll = 10 (1024 secs), step was done within 5 minutes
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* after first reply which indicated that our clock is 14 seconds off.
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* - on step, do not discard d_dispersion data of the existing datapoints,
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* do not clear reachable_bits. This prevents discarding first ~8
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* datapoints after the step.
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*/
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#define RETRY_INTERVAL 5 /* on error, retry in N secs */
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#define RESPONSE_INTERVAL 15 /* wait for reply up to N secs */
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#define INITIAL_SAMPLES 4 /* how many samples do we want for init */
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#define BAD_DELAY_GROWTH 4 /* drop packet if its delay grew by more than this */
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/* Clock discipline parameters and constants */
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/* Step threshold (sec). std ntpd uses 0.128.
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* Using exact power of 2 (1/8) results in smaller code */
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#define STEP_THRESHOLD 0.125
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#define WATCH_THRESHOLD 128 /* stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */
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/* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */
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//UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */
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#define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */
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#define BURSTPOLL 0 /* initial poll */
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#define MINPOLL 5 /* minimum poll interval. std ntpd uses 6 (6: 64 sec) */
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/* If we got largish offset from a peer, cap next query interval
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* for this peer by this many seconds:
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*/
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#define BIGOFF_INTERVAL (1 << 6)
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/* If offset > discipline_jitter * POLLADJ_GATE, and poll interval is >= 2^BIGPOLL,
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* then it is decreased _at once_. (If < 2^BIGPOLL, it will be decreased _eventually_).
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*/
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#define BIGPOLL 10 /* 2^10 sec ~= 17 min */
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#define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h). std ntpd uses 17 */
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/* Actively lower poll when we see such big offsets.
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* With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively
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* if offset increases over ~0.04 sec */
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#define POLLDOWN_OFFSET (STEP_THRESHOLD / 3)
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#define MINDISP 0.01 /* minimum dispersion (sec) */
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#define MAXDISP 16 /* maximum dispersion (sec) */
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#define MAXSTRAT 16 /* maximum stratum (infinity metric) */
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#define MAXDIST 1 /* distance threshold (sec) */
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#define MIN_SELECTED 1 /* minimum intersection survivors */
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#define MIN_CLUSTERED 3 /* minimum cluster survivors */
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#define MAXDRIFT 0.000500 /* frequency drift we can correct (500 PPM) */
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/* Poll-adjust threshold.
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* When we see that offset is small enough compared to discipline jitter,
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* we grow a counter: += MINPOLL. When counter goes over POLLADJ_LIMIT,
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* we poll_exp++. If offset isn't small, counter -= poll_exp*2,
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* and when it goes below -POLLADJ_LIMIT, we poll_exp--.
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* (Bumped from 30 to 40 since otherwise I often see poll_exp going *2* steps down)
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*/
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#define POLLADJ_LIMIT 40
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/* If offset < discipline_jitter * POLLADJ_GATE, then we decide to increase
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* poll interval (we think we can't improve timekeeping
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* by staying at smaller poll).
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*/
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#define POLLADJ_GATE 4
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#define TIMECONST_HACK_GATE 2
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/* Compromise Allan intercept (sec). doc uses 1500, std ntpd uses 512 */
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#define ALLAN 512
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/* PLL loop gain */
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#define PLL 65536
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/* FLL loop gain [why it depends on MAXPOLL??] */
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#define FLL (MAXPOLL + 1)
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/* Parameter averaging constant */
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#define AVG 4
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enum {
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NTP_VERSION = 4,
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NTP_MAXSTRATUM = 15,
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NTP_DIGESTSIZE = 16,
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NTP_MSGSIZE_NOAUTH = 48,
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NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
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/* Status Masks */
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MODE_MASK = (7 << 0),
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VERSION_MASK = (7 << 3),
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VERSION_SHIFT = 3,
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LI_MASK = (3 << 6),
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/* Leap Second Codes (high order two bits of m_status) */
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LI_NOWARNING = (0 << 6), /* no warning */
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LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
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LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
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LI_ALARM = (3 << 6), /* alarm condition */
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/* Mode values */
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MODE_RES0 = 0, /* reserved */
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MODE_SYM_ACT = 1, /* symmetric active */
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MODE_SYM_PAS = 2, /* symmetric passive */
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MODE_CLIENT = 3, /* client */
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MODE_SERVER = 4, /* server */
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MODE_BROADCAST = 5, /* broadcast */
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MODE_RES1 = 6, /* reserved for NTP control message */
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MODE_RES2 = 7, /* reserved for private use */
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};
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//TODO: better base selection
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#define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
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#define NUM_DATAPOINTS 8
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typedef struct {
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uint32_t int_partl;
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uint32_t fractionl;
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} l_fixedpt_t;
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typedef struct {
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uint16_t int_parts;
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uint16_t fractions;
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} s_fixedpt_t;
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typedef struct {
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uint8_t m_status; /* status of local clock and leap info */
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uint8_t m_stratum;
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uint8_t m_ppoll; /* poll value */
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int8_t m_precision_exp;
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s_fixedpt_t m_rootdelay;
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s_fixedpt_t m_rootdisp;
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uint32_t m_refid;
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l_fixedpt_t m_reftime;
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l_fixedpt_t m_orgtime;
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l_fixedpt_t m_rectime;
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l_fixedpt_t m_xmttime;
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uint32_t m_keyid;
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uint8_t m_digest[NTP_DIGESTSIZE];
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} msg_t;
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typedef struct {
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double d_offset;
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double d_recv_time;
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double d_dispersion;
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} datapoint_t;
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typedef struct {
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len_and_sockaddr *p_lsa;
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char *p_dotted;
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int p_fd;
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int datapoint_idx;
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uint32_t lastpkt_refid;
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uint8_t lastpkt_status;
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uint8_t lastpkt_stratum;
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uint8_t reachable_bits;
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/* when to send new query (if p_fd == -1)
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* or when receive times out (if p_fd >= 0): */
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double next_action_time;
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double p_xmttime;
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double lastpkt_recv_time;
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double lastpkt_delay;
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double lastpkt_rootdelay;
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double lastpkt_rootdisp;
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/* produced by filter algorithm: */
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double filter_offset;
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double filter_dispersion;
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double filter_jitter;
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datapoint_t filter_datapoint[NUM_DATAPOINTS];
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/* last sent packet: */
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msg_t p_xmt_msg;
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} peer_t;
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#define USING_KERNEL_PLL_LOOP 1
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#define USING_INITIAL_FREQ_ESTIMATION 0
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enum {
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OPT_n = (1 << 0),
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OPT_q = (1 << 1),
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OPT_N = (1 << 2),
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OPT_x = (1 << 3),
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/* Insert new options above this line. */
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/* Non-compat options: */
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OPT_w = (1 << 4),
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OPT_p = (1 << 5),
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OPT_S = (1 << 6),
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OPT_l = (1 << 7) * ENABLE_FEATURE_NTPD_SERVER,
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/* We hijack some bits for other purposes */
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OPT_qq = (1 << 31),
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};
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struct globals {
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double cur_time;
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/* total round trip delay to currently selected reference clock */
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double rootdelay;
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/* reference timestamp: time when the system clock was last set or corrected */
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double reftime;
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/* total dispersion to currently selected reference clock */
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double rootdisp;
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double last_script_run;
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char *script_name;
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llist_t *ntp_peers;
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#if ENABLE_FEATURE_NTPD_SERVER
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int listen_fd;
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# define G_listen_fd (G.listen_fd)
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#else
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# define G_listen_fd (-1)
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#endif
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unsigned verbose;
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unsigned peer_cnt;
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/* refid: 32-bit code identifying the particular server or reference clock
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* in stratum 0 packets this is a four-character ASCII string,
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* called the kiss code, used for debugging and monitoring
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* in stratum 1 packets this is a four-character ASCII string
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* assigned to the reference clock by IANA. Example: "GPS "
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* in stratum 2+ packets, it's IPv4 address or 4 first bytes
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* of MD5 hash of IPv6
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*/
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uint32_t refid;
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uint8_t ntp_status;
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/* precision is defined as the larger of the resolution and time to
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* read the clock, in log2 units. For instance, the precision of a
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* mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
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* system clock hardware representation is to the nanosecond.
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*
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* Delays, jitters of various kinds are clamped down to precision.
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*
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* If precision_sec is too large, discipline_jitter gets clamped to it
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* and if offset is smaller than discipline_jitter * POLLADJ_GATE, poll
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* interval grows even though we really can benefit from staying at
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* smaller one, collecting non-lagged datapoits and correcting offset.
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* (Lagged datapoits exist when poll_exp is large but we still have
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* systematic offset error - the time distance between datapoints
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* is significant and older datapoints have smaller offsets.
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* This makes our offset estimation a bit smaller than reality)
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* Due to this effect, setting G_precision_sec close to
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* STEP_THRESHOLD isn't such a good idea - offsets may grow
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* too big and we will step. I observed it with -6.
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*
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* OTOH, setting precision_sec far too small would result in futile
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* attempts to syncronize to an unachievable precision.
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*
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* -6 is 1/64 sec, -7 is 1/128 sec and so on.
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* -8 is 1/256 ~= 0.003906 (worked well for me --vda)
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* -9 is 1/512 ~= 0.001953 (let's try this for some time)
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*/
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#define G_precision_exp -9
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/*
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* G_precision_exp is used only for construction outgoing packets.
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* It's ok to set G_precision_sec to a slightly different value
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* (One which is "nicer looking" in logs).
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* Exact value would be (1.0 / (1 << (- G_precision_exp))):
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*/
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#define G_precision_sec 0.002
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uint8_t stratum;
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/* Bool. After set to 1, never goes back to 0: */
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smallint initial_poll_complete;
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#define STATE_NSET 0 /* initial state, "nothing is set" */
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//#define STATE_FSET 1 /* frequency set from file */
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//#define STATE_SPIK 2 /* spike detected */
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//#define STATE_FREQ 3 /* initial frequency */
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#define STATE_SYNC 4 /* clock synchronized (normal operation) */
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uint8_t discipline_state; // doc calls it c.state
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uint8_t poll_exp; // s.poll
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int polladj_count; // c.count
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long kernel_freq_drift;
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peer_t *last_update_peer;
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double last_update_offset; // c.last
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double last_update_recv_time; // s.t
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double discipline_jitter; // c.jitter
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/* Since we only compare it with ints, can simplify code
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* by not making this variable floating point:
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*/
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unsigned offset_to_jitter_ratio;
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//double cluster_offset; // s.offset
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//double cluster_jitter; // s.jitter
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#if !USING_KERNEL_PLL_LOOP
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double discipline_freq_drift; // c.freq
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/* Maybe conditionally calculate wander? it's used only for logging */
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double discipline_wander; // c.wander
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#endif
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};
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#define G (*ptr_to_globals)
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static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
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#define VERB1 if (MAX_VERBOSE && G.verbose)
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#define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
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#define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
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#define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
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#define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
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#define VERB6 if (MAX_VERBOSE >= 6 && G.verbose >= 6)
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static double LOG2D(int a)
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{
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if (a < 0)
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return 1.0 / (1UL << -a);
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return 1UL << a;
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}
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static ALWAYS_INLINE double SQUARE(double x)
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{
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return x * x;
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}
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static ALWAYS_INLINE double MAXD(double a, double b)
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{
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if (a > b)
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return a;
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return b;
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}
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static ALWAYS_INLINE double MIND(double a, double b)
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{
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if (a < b)
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return a;
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return b;
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}
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static NOINLINE double my_SQRT(double X)
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{
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union {
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float f;
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int32_t i;
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} v;
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double invsqrt;
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double Xhalf = X * 0.5;
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/* Fast and good approximation to 1/sqrt(X), black magic */
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v.f = X;
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/*v.i = 0x5f3759df - (v.i >> 1);*/
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v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
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invsqrt = v.f; /* better than 0.2% accuracy */
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/* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
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* f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
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* f'(x) = -2/(x*x*x)
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* f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
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* x1 = x0 - (X*x0*x0*x0/2 - x0/2) = 1.5*x0 - X*x0*x0*x0/2 = x0*(1.5 - (X/2)*x0*x0)
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*/
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invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
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/* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
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/* With 4 iterations, more than half results will be exact,
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* at 6th iterations result stabilizes with about 72% results exact.
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* We are well satisfied with 0.05% accuracy.
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*/
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return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
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}
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static ALWAYS_INLINE double SQRT(double X)
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{
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/* If this arch doesn't use IEEE 754 floats, fall back to using libm */
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if (sizeof(float) != 4)
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return sqrt(X);
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/* This avoids needing libm, saves about 0.5k on x86-32 */
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|
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++) {
|
|
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
|
|
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();
|
|
|
|
/* 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;
|
|
|
|
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;
|
|
}
|
|
|
|
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);
|
|
|
|
/* 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 */
|
|
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;
|
|
}
|
|
|
|
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);
|
|
|
|
/* 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;
|
|
VERB5 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("survivors:%d%s",
|
|
num_survivors,
|
|
", no peer 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) {
|
|
VERB4 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;
|
|
}
|
|
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;
|
|
}
|
|
|
|
/* 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++;
|
|
}
|
|
}
|
|
|
|
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
|
|
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.
|
|
*/
|
|
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;
|
|
|
|
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("update from %s: same or older datapoint, not using it",
|
|
p->p_dotted);
|
|
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) {
|
|
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
|
|
|
|
/* 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
|
|
|
|
/* 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);
|
|
}
|
|
|
|
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) {
|
|
VERB4 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
|
|
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 (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);
|
|
}
|
|
|
|
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);
|
|
|
|
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);
|
|
VERB4 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 */
|
|
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;
|
|
|
|
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->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
|
|
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
|
|
*
|
|
* 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;
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
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
|
|
*/
|
|
);
|
|
}
|
|
|
|
/* 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);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 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;
|
|
}
|
|
|
|
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 (!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 (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 */
|
|
}
|
|
}
|
|
|
|
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
|