1 | /*
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2 | * NTP client/server, based on OpenNTPD 3.9p1
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3 | *
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4 | * Author: Adam Tkac <vonsch@gmail.com>
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5 | *
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6 | * Licensed under GPLv2, see file LICENSE in this source tree.
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7 | *
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8 | * Parts of OpenNTPD clock syncronization code is replaced by
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9 | * code which is based on ntp-4.2.6, whuch carries the following
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10 | * copyright notice:
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11 | *
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12 | ***********************************************************************
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13 | * *
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14 | * Copyright (c) University of Delaware 1992-2009 *
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15 | * *
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16 | * Permission to use, copy, modify, and distribute this software and *
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17 | * its documentation for any purpose with or without fee is hereby *
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18 | * granted, provided that the above copyright notice appears in all *
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19 | * copies and that both the copyright notice and this permission *
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20 | * notice appear in supporting documentation, and that the name *
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21 | * University of Delaware not be used in advertising or publicity *
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22 | * pertaining to distribution of the software without specific, *
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23 | * written prior permission. The University of Delaware makes no *
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24 | * representations about the suitability this software for any *
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25 | * purpose. It is provided "as is" without express or implied *
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26 | * warranty. *
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27 | * *
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28 | ***********************************************************************
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29 | */
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30 | #include "libbb.h"
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31 | #include <math.h>
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32 | #include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
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33 | #include <sys/timex.h>
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34 | #ifndef IPTOS_LOWDELAY
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35 | # define IPTOS_LOWDELAY 0x10
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36 | #endif
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37 | #ifndef IP_PKTINFO
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38 | # error "Sorry, your kernel has to support IP_PKTINFO"
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39 | #endif
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40 |
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41 |
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42 | /* Verbosity control (max level of -dddd options accepted).
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43 | * max 5 is very talkative (and bloated). 2 is non-bloated,
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44 | * production level setting.
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45 | */
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46 | #define MAX_VERBOSE 2
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47 |
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48 |
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49 | /* High-level description of the algorithm:
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50 | *
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51 | * We start running with very small poll_exp, BURSTPOLL,
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52 | * in order to quickly accumulate INITIAL_SAMPLES datapoints
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53 | * for each peer. Then, time is stepped if the offset is larger
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54 | * than STEP_THRESHOLD, otherwise it isn't; anyway, we enlarge
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55 | * poll_exp to MINPOLL and enter frequency measurement step:
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56 | * we collect new datapoints but ignore them for WATCH_THRESHOLD
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57 | * seconds. After WATCH_THRESHOLD seconds we look at accumulated
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58 | * offset and estimate frequency drift.
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59 | *
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60 | * (frequency measurement step seems to not be strictly needed,
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61 | * it is conditionally disabled with USING_INITIAL_FREQ_ESTIMATION
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62 | * define set to 0)
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63 | *
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64 | * After this, we enter "steady state": we collect a datapoint,
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65 | * we select the best peer, if this datapoint is not a new one
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66 | * (IOW: if this datapoint isn't for selected peer), sleep
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67 | * and collect another one; otherwise, use its offset to update
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68 | * frequency drift, if offset is somewhat large, reduce poll_exp,
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69 | * otherwise increase poll_exp.
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70 | *
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71 | * If offset is larger than STEP_THRESHOLD, which shouldn't normally
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72 | * happen, we assume that something "bad" happened (computer
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73 | * was hibernated, someone set totally wrong date, etc),
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74 | * then the time is stepped, all datapoints are discarded,
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75 | * and we go back to steady state.
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76 | */
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77 |
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78 | #define RETRY_INTERVAL 5 /* on error, retry in N secs */
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79 | #define RESPONSE_INTERVAL 15 /* wait for reply up to N secs */
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80 | #define INITIAL_SAMPLES 4 /* how many samples do we want for init */
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81 |
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82 | /* Clock discipline parameters and constants */
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83 |
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84 | /* Step threshold (sec). std ntpd uses 0.128.
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85 | * Using exact power of 2 (1/8) results in smaller code */
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86 | #define STEP_THRESHOLD 0.125
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87 | #define WATCH_THRESHOLD 128 /* stepout threshold (sec). std ntpd uses 900 (11 mins (!)) */
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88 | /* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */
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89 | //UNUSED: #define PANIC_THRESHOLD 1000 /* panic threshold (sec) */
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90 |
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91 | #define FREQ_TOLERANCE 0.000015 /* frequency tolerance (15 PPM) */
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92 | #define BURSTPOLL 0 /* initial poll */
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93 | #define MINPOLL 5 /* minimum poll interval. std ntpd uses 6 (6: 64 sec) */
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94 | #define BIGPOLL 10 /* drop to lower poll at any trouble (10: 17 min) */
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95 | #define MAXPOLL 12 /* maximum poll interval (12: 1.1h, 17: 36.4h). std ntpd uses 17 */
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96 | /* Actively lower poll when we see such big offsets.
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97 | * With STEP_THRESHOLD = 0.125, it means we try to sync more aggressively
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98 | * if offset increases over 0.03 sec */
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99 | #define POLLDOWN_OFFSET (STEP_THRESHOLD / 4)
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100 | #define MINDISP 0.01 /* minimum dispersion (sec) */
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101 | #define MAXDISP 16 /* maximum dispersion (sec) */
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102 | #define MAXSTRAT 16 /* maximum stratum (infinity metric) */
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103 | #define MAXDIST 1 /* distance threshold (sec) */
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104 | #define MIN_SELECTED 1 /* minimum intersection survivors */
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105 | #define MIN_CLUSTERED 3 /* minimum cluster survivors */
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106 |
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107 | #define MAXDRIFT 0.000500 /* frequency drift we can correct (500 PPM) */
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108 |
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109 | /* Poll-adjust threshold.
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110 | * When we see that offset is small enough compared to discipline jitter,
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111 | * we grow a counter: += MINPOLL. When it goes over POLLADJ_LIMIT,
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112 | * we poll_exp++. If offset isn't small, counter -= poll_exp*2,
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113 | * and when it goes below -POLLADJ_LIMIT, we poll_exp--
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114 | * (bumped from 30 to 36 since otherwise I often see poll_exp going *2* steps down)
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115 | */
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116 | #define POLLADJ_LIMIT 36
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117 | /* If offset < POLLADJ_GATE * discipline_jitter, then we can increase
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118 | * poll interval (we think we can't improve timekeeping
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119 | * by staying at smaller poll).
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120 | */
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121 | #define POLLADJ_GATE 4
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122 | /* Compromise Allan intercept (sec). doc uses 1500, std ntpd uses 512 */
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123 | #define ALLAN 512
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124 | /* PLL loop gain */
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125 | #define PLL 65536
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126 | /* FLL loop gain [why it depends on MAXPOLL??] */
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127 | #define FLL (MAXPOLL + 1)
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128 | /* Parameter averaging constant */
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129 | #define AVG 4
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130 |
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131 |
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132 | enum {
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133 | NTP_VERSION = 4,
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134 | NTP_MAXSTRATUM = 15,
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135 |
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136 | NTP_DIGESTSIZE = 16,
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137 | NTP_MSGSIZE_NOAUTH = 48,
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138 | NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
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139 |
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140 | /* Status Masks */
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141 | MODE_MASK = (7 << 0),
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142 | VERSION_MASK = (7 << 3),
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143 | VERSION_SHIFT = 3,
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144 | LI_MASK = (3 << 6),
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145 |
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146 | /* Leap Second Codes (high order two bits of m_status) */
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147 | LI_NOWARNING = (0 << 6), /* no warning */
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148 | LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
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149 | LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
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150 | LI_ALARM = (3 << 6), /* alarm condition */
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151 |
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152 | /* Mode values */
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153 | MODE_RES0 = 0, /* reserved */
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154 | MODE_SYM_ACT = 1, /* symmetric active */
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155 | MODE_SYM_PAS = 2, /* symmetric passive */
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156 | MODE_CLIENT = 3, /* client */
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157 | MODE_SERVER = 4, /* server */
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158 | MODE_BROADCAST = 5, /* broadcast */
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159 | MODE_RES1 = 6, /* reserved for NTP control message */
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160 | MODE_RES2 = 7, /* reserved for private use */
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161 | };
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162 |
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163 | //TODO: better base selection
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164 | #define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
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165 |
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166 | #define NUM_DATAPOINTS 8
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167 |
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168 | typedef struct {
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169 | uint32_t int_partl;
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170 | uint32_t fractionl;
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171 | } l_fixedpt_t;
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172 |
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173 | typedef struct {
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174 | uint16_t int_parts;
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175 | uint16_t fractions;
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176 | } s_fixedpt_t;
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177 |
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178 | typedef struct {
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179 | uint8_t m_status; /* status of local clock and leap info */
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180 | uint8_t m_stratum;
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181 | uint8_t m_ppoll; /* poll value */
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182 | int8_t m_precision_exp;
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183 | s_fixedpt_t m_rootdelay;
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184 | s_fixedpt_t m_rootdisp;
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185 | uint32_t m_refid;
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186 | l_fixedpt_t m_reftime;
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187 | l_fixedpt_t m_orgtime;
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188 | l_fixedpt_t m_rectime;
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189 | l_fixedpt_t m_xmttime;
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190 | uint32_t m_keyid;
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191 | uint8_t m_digest[NTP_DIGESTSIZE];
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192 | } msg_t;
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193 |
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194 | typedef struct {
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195 | double d_recv_time;
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196 | double d_offset;
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197 | double d_dispersion;
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198 | } datapoint_t;
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199 |
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200 | typedef struct {
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201 | len_and_sockaddr *p_lsa;
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202 | char *p_dotted;
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203 | /* when to send new query (if p_fd == -1)
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204 | * or when receive times out (if p_fd >= 0): */
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205 | int p_fd;
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206 | int datapoint_idx;
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207 | uint32_t lastpkt_refid;
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208 | uint8_t lastpkt_status;
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209 | uint8_t lastpkt_stratum;
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210 | uint8_t reachable_bits;
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211 | double next_action_time;
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212 | double p_xmttime;
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213 | double lastpkt_recv_time;
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214 | double lastpkt_delay;
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215 | double lastpkt_rootdelay;
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216 | double lastpkt_rootdisp;
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217 | /* produced by filter algorithm: */
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218 | double filter_offset;
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219 | double filter_dispersion;
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220 | double filter_jitter;
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221 | datapoint_t filter_datapoint[NUM_DATAPOINTS];
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222 | /* last sent packet: */
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223 | msg_t p_xmt_msg;
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224 | } peer_t;
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225 |
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226 |
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227 | #define USING_KERNEL_PLL_LOOP 1
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228 | #define USING_INITIAL_FREQ_ESTIMATION 0
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229 |
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230 | enum {
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231 | OPT_n = (1 << 0),
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232 | OPT_q = (1 << 1),
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233 | OPT_N = (1 << 2),
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234 | OPT_x = (1 << 3),
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235 | /* Insert new options above this line. */
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236 | /* Non-compat options: */
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237 | OPT_w = (1 << 4),
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238 | OPT_p = (1 << 5),
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239 | OPT_S = (1 << 6),
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240 | OPT_l = (1 << 7) * ENABLE_FEATURE_NTPD_SERVER,
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241 | };
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242 |
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243 | struct globals {
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244 | double cur_time;
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245 | /* total round trip delay to currently selected reference clock */
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246 | double rootdelay;
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247 | /* reference timestamp: time when the system clock was last set or corrected */
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248 | double reftime;
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249 | /* total dispersion to currently selected reference clock */
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250 | double rootdisp;
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251 |
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252 | double last_script_run;
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253 | char *script_name;
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254 | llist_t *ntp_peers;
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255 | #if ENABLE_FEATURE_NTPD_SERVER
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256 | int listen_fd;
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257 | #endif
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258 | unsigned verbose;
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259 | unsigned peer_cnt;
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260 | /* refid: 32-bit code identifying the particular server or reference clock
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261 | * in stratum 0 packets this is a four-character ASCII string,
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262 | * called the kiss code, used for debugging and monitoring
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263 | * in stratum 1 packets this is a four-character ASCII string
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264 | * assigned to the reference clock by IANA. Example: "GPS "
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265 | * in stratum 2+ packets, it's IPv4 address or 4 first bytes of MD5 hash of IPv6
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266 | */
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267 | uint32_t refid;
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268 | uint8_t ntp_status;
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269 | /* precision is defined as the larger of the resolution and time to
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270 | * read the clock, in log2 units. For instance, the precision of a
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271 | * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
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272 | * system clock hardware representation is to the nanosecond.
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273 | *
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274 | * Delays, jitters of various kinds are clamper down to precision.
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275 | *
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276 | * If precision_sec is too large, discipline_jitter gets clamped to it
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277 | * and if offset is much smaller than discipline_jitter, poll interval
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278 | * grows even though we really can benefit from staying at smaller one,
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279 | * collecting non-lagged datapoits and correcting the offset.
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280 | * (Lagged datapoits exist when poll_exp is large but we still have
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281 | * systematic offset error - the time distance between datapoints
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282 | * is significat and older datapoints have smaller offsets.
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283 | * This makes our offset estimation a bit smaller than reality)
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284 | * Due to this effect, setting G_precision_sec close to
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285 | * STEP_THRESHOLD isn't such a good idea - offsets may grow
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286 | * too big and we will step. I observed it with -6.
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287 | *
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288 | * OTOH, setting precision too small would result in futile attempts
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289 | * to syncronize to the unachievable precision.
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290 | *
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291 | * -6 is 1/64 sec, -7 is 1/128 sec and so on.
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292 | */
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293 | #define G_precision_exp -8
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294 | #define G_precision_sec (1.0 / (1 << (- G_precision_exp)))
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295 | uint8_t stratum;
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296 | /* Bool. After set to 1, never goes back to 0: */
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297 | smallint initial_poll_complete;
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298 |
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299 | #define STATE_NSET 0 /* initial state, "nothing is set" */
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300 | //#define STATE_FSET 1 /* frequency set from file */
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301 | #define STATE_SPIK 2 /* spike detected */
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302 | //#define STATE_FREQ 3 /* initial frequency */
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303 | #define STATE_SYNC 4 /* clock synchronized (normal operation) */
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304 | uint8_t discipline_state; // doc calls it c.state
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305 | uint8_t poll_exp; // s.poll
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306 | int polladj_count; // c.count
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307 | long kernel_freq_drift;
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308 | peer_t *last_update_peer;
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309 | double last_update_offset; // c.last
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310 | double last_update_recv_time; // s.t
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311 | double discipline_jitter; // c.jitter
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312 | //double cluster_offset; // s.offset
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313 | //double cluster_jitter; // s.jitter
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314 | #if !USING_KERNEL_PLL_LOOP
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315 | double discipline_freq_drift; // c.freq
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316 | /* Maybe conditionally calculate wander? it's used only for logging */
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317 | double discipline_wander; // c.wander
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318 | #endif
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319 | };
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320 | #define G (*ptr_to_globals)
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321 |
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322 | static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
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323 |
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324 |
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325 | #define VERB1 if (MAX_VERBOSE && G.verbose)
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326 | #define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2)
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327 | #define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3)
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328 | #define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4)
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329 | #define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5)
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330 |
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331 |
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332 | static double LOG2D(int a)
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333 | {
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334 | if (a < 0)
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335 | return 1.0 / (1UL << -a);
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336 | return 1UL << a;
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337 | }
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338 | static ALWAYS_INLINE double SQUARE(double x)
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339 | {
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340 | return x * x;
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341 | }
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342 | static ALWAYS_INLINE double MAXD(double a, double b)
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343 | {
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344 | if (a > b)
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345 | return a;
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346 | return b;
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347 | }
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348 | static ALWAYS_INLINE double MIND(double a, double b)
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349 | {
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350 | if (a < b)
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351 | return a;
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352 | return b;
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353 | }
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354 | static NOINLINE double my_SQRT(double X)
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355 | {
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356 | union {
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357 | float f;
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358 | int32_t i;
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359 | } v;
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360 | double invsqrt;
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361 | double Xhalf = X * 0.5;
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362 |
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363 | /* Fast and good approximation to 1/sqrt(X), black magic */
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364 | v.f = X;
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365 | /*v.i = 0x5f3759df - (v.i >> 1);*/
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366 | v.i = 0x5f375a86 - (v.i >> 1); /* - this constant is slightly better */
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367 | invsqrt = v.f; /* better than 0.2% accuracy */
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368 |
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369 | /* Refining it using Newton's method: x1 = x0 - f(x0)/f'(x0)
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370 | * f(x) = 1/(x*x) - X (f==0 when x = 1/sqrt(X))
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371 | * f'(x) = -2/(x*x*x)
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372 | * f(x)/f'(x) = (X - 1/(x*x)) / (2/(x*x*x)) = X*x*x*x/2 - x/2
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373 | * 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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374 | */
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375 | invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); /* ~0.05% accuracy */
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376 | /* invsqrt = invsqrt * (1.5 - Xhalf * invsqrt * invsqrt); 2nd iter: ~0.0001% accuracy */
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377 | /* With 4 iterations, more than half results will be exact,
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378 | * at 6th iterations result stabilizes with about 72% results exact.
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379 | * We are well satisfied with 0.05% accuracy.
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380 | */
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381 |
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382 | return X * invsqrt; /* X * 1/sqrt(X) ~= sqrt(X) */
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383 | }
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384 | static ALWAYS_INLINE double SQRT(double X)
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385 | {
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386 | /* If this arch doesn't use IEEE 754 floats, fall back to using libm */
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387 | if (sizeof(float) != 4)
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388 | return sqrt(X);
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389 |
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390 | /* This avoids needing libm, saves about 0.5k on x86-32 */
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391 | return my_SQRT(X);
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392 | }
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393 |
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394 | static double
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395 | gettime1900d(void)
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396 | {
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397 | struct timeval tv;
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398 | gettimeofday(&tv, NULL); /* never fails */
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399 | G.cur_time = tv.tv_sec + (1.0e-6 * tv.tv_usec) + OFFSET_1900_1970;
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400 | return G.cur_time;
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401 | }
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402 |
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403 | static void
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404 | d_to_tv(double d, struct timeval *tv)
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405 | {
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406 | tv->tv_sec = (long)d;
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407 | tv->tv_usec = (d - tv->tv_sec) * 1000000;
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408 | }
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409 |
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410 | static double
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411 | lfp_to_d(l_fixedpt_t lfp)
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412 | {
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413 | double ret;
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414 | lfp.int_partl = ntohl(lfp.int_partl);
|
---|
415 | lfp.fractionl = ntohl(lfp.fractionl);
|
---|
416 | ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
|
---|
417 | return ret;
|
---|
418 | }
|
---|
419 | static double
|
---|
420 | sfp_to_d(s_fixedpt_t sfp)
|
---|
421 | {
|
---|
422 | double ret;
|
---|
423 | sfp.int_parts = ntohs(sfp.int_parts);
|
---|
424 | sfp.fractions = ntohs(sfp.fractions);
|
---|
425 | ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
|
---|
426 | return ret;
|
---|
427 | }
|
---|
428 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
429 | static l_fixedpt_t
|
---|
430 | d_to_lfp(double d)
|
---|
431 | {
|
---|
432 | l_fixedpt_t lfp;
|
---|
433 | lfp.int_partl = (uint32_t)d;
|
---|
434 | lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
|
---|
435 | lfp.int_partl = htonl(lfp.int_partl);
|
---|
436 | lfp.fractionl = htonl(lfp.fractionl);
|
---|
437 | return lfp;
|
---|
438 | }
|
---|
439 | static s_fixedpt_t
|
---|
440 | d_to_sfp(double d)
|
---|
441 | {
|
---|
442 | s_fixedpt_t sfp;
|
---|
443 | sfp.int_parts = (uint16_t)d;
|
---|
444 | sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
|
---|
445 | sfp.int_parts = htons(sfp.int_parts);
|
---|
446 | sfp.fractions = htons(sfp.fractions);
|
---|
447 | return sfp;
|
---|
448 | }
|
---|
449 | #endif
|
---|
450 |
|
---|
451 | static double
|
---|
452 | dispersion(const datapoint_t *dp)
|
---|
453 | {
|
---|
454 | return dp->d_dispersion + FREQ_TOLERANCE * (G.cur_time - dp->d_recv_time);
|
---|
455 | }
|
---|
456 |
|
---|
457 | static double
|
---|
458 | root_distance(peer_t *p)
|
---|
459 | {
|
---|
460 | /* The root synchronization distance is the maximum error due to
|
---|
461 | * all causes of the local clock relative to the primary server.
|
---|
462 | * It is defined as half the total delay plus total dispersion
|
---|
463 | * plus peer jitter.
|
---|
464 | */
|
---|
465 | return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2
|
---|
466 | + p->lastpkt_rootdisp
|
---|
467 | + p->filter_dispersion
|
---|
468 | + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time)
|
---|
469 | + p->filter_jitter;
|
---|
470 | }
|
---|
471 |
|
---|
472 | static void
|
---|
473 | set_next(peer_t *p, unsigned t)
|
---|
474 | {
|
---|
475 | p->next_action_time = G.cur_time + t;
|
---|
476 | }
|
---|
477 |
|
---|
478 | /*
|
---|
479 | * Peer clock filter and its helpers
|
---|
480 | */
|
---|
481 | static void
|
---|
482 | filter_datapoints(peer_t *p)
|
---|
483 | {
|
---|
484 | int i, idx;
|
---|
485 | int got_newest;
|
---|
486 | double minoff, maxoff, wavg, sum, w;
|
---|
487 | double x = x; /* for compiler */
|
---|
488 | double oldest_off = oldest_off;
|
---|
489 | double oldest_age = oldest_age;
|
---|
490 | double newest_off = newest_off;
|
---|
491 | double newest_age = newest_age;
|
---|
492 |
|
---|
493 | minoff = maxoff = p->filter_datapoint[0].d_offset;
|
---|
494 | for (i = 1; i < NUM_DATAPOINTS; i++) {
|
---|
495 | if (minoff > p->filter_datapoint[i].d_offset)
|
---|
496 | minoff = p->filter_datapoint[i].d_offset;
|
---|
497 | if (maxoff < p->filter_datapoint[i].d_offset)
|
---|
498 | maxoff = p->filter_datapoint[i].d_offset;
|
---|
499 | }
|
---|
500 |
|
---|
501 | idx = p->datapoint_idx; /* most recent datapoint */
|
---|
502 | /* Average offset:
|
---|
503 | * Drop two outliers and take weighted average of the rest:
|
---|
504 | * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32
|
---|
505 | * we use older6/32, not older6/64 since sum of weights should be 1:
|
---|
506 | * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1
|
---|
507 | */
|
---|
508 | wavg = 0;
|
---|
509 | w = 0.5;
|
---|
510 | /* n-1
|
---|
511 | * --- dispersion(i)
|
---|
512 | * filter_dispersion = \ -------------
|
---|
513 | * / (i+1)
|
---|
514 | * --- 2
|
---|
515 | * i=0
|
---|
516 | */
|
---|
517 | got_newest = 0;
|
---|
518 | sum = 0;
|
---|
519 | for (i = 0; i < NUM_DATAPOINTS; i++) {
|
---|
520 | VERB4 {
|
---|
521 | bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s",
|
---|
522 | i,
|
---|
523 | p->filter_datapoint[idx].d_offset,
|
---|
524 | p->filter_datapoint[idx].d_dispersion, dispersion(&p->filter_datapoint[idx]),
|
---|
525 | G.cur_time - p->filter_datapoint[idx].d_recv_time,
|
---|
526 | (minoff == p->filter_datapoint[idx].d_offset || maxoff == p->filter_datapoint[idx].d_offset)
|
---|
527 | ? " (outlier by offset)" : ""
|
---|
528 | );
|
---|
529 | }
|
---|
530 |
|
---|
531 | sum += dispersion(&p->filter_datapoint[idx]) / (2 << i);
|
---|
532 |
|
---|
533 | if (minoff == p->filter_datapoint[idx].d_offset) {
|
---|
534 | minoff -= 1; /* so that we don't match it ever again */
|
---|
535 | } else
|
---|
536 | if (maxoff == p->filter_datapoint[idx].d_offset) {
|
---|
537 | maxoff += 1;
|
---|
538 | } else {
|
---|
539 | oldest_off = p->filter_datapoint[idx].d_offset;
|
---|
540 | oldest_age = G.cur_time - p->filter_datapoint[idx].d_recv_time;
|
---|
541 | if (!got_newest) {
|
---|
542 | got_newest = 1;
|
---|
543 | newest_off = oldest_off;
|
---|
544 | newest_age = oldest_age;
|
---|
545 | }
|
---|
546 | x = oldest_off * w;
|
---|
547 | wavg += x;
|
---|
548 | w /= 2;
|
---|
549 | }
|
---|
550 |
|
---|
551 | idx = (idx - 1) & (NUM_DATAPOINTS - 1);
|
---|
552 | }
|
---|
553 | p->filter_dispersion = sum;
|
---|
554 | wavg += x; /* add another older6/64 to form older6/32 */
|
---|
555 | /* Fix systematic underestimation with large poll intervals.
|
---|
556 | * Imagine that we still have a bit of uncorrected drift,
|
---|
557 | * and poll interval is big (say, 100 sec). Offsets form a progression:
|
---|
558 | * 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 - 0.7 is most recent.
|
---|
559 | * The algorithm above drops 0.0 and 0.7 as outliers,
|
---|
560 | * and then we have this estimation, ~25% off from 0.7:
|
---|
561 | * 0.1/32 + 0.2/32 + 0.3/16 + 0.4/8 + 0.5/4 + 0.6/2 = 0.503125
|
---|
562 | */
|
---|
563 | x = oldest_age - newest_age;
|
---|
564 | if (x != 0) {
|
---|
565 | x = newest_age / x; /* in above example, 100 / (600 - 100) */
|
---|
566 | if (x < 1) { /* paranoia check */
|
---|
567 | x = (newest_off - oldest_off) * x; /* 0.5 * 100/500 = 0.1 */
|
---|
568 | wavg += x;
|
---|
569 | }
|
---|
570 | }
|
---|
571 | p->filter_offset = wavg;
|
---|
572 |
|
---|
573 | /* +----- -----+ ^ 1/2
|
---|
574 | * | n-1 |
|
---|
575 | * | --- |
|
---|
576 | * | 1 \ 2 |
|
---|
577 | * filter_jitter = | --- * / (avg-offset_j) |
|
---|
578 | * | n --- |
|
---|
579 | * | j=0 |
|
---|
580 | * +----- -----+
|
---|
581 | * where n is the number of valid datapoints in the filter (n > 1);
|
---|
582 | * if filter_jitter < precision then filter_jitter = precision
|
---|
583 | */
|
---|
584 | sum = 0;
|
---|
585 | for (i = 0; i < NUM_DATAPOINTS; i++) {
|
---|
586 | sum += SQUARE(wavg - p->filter_datapoint[i].d_offset);
|
---|
587 | }
|
---|
588 | sum = SQRT(sum / NUM_DATAPOINTS);
|
---|
589 | p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
|
---|
590 |
|
---|
591 | VERB3 bb_error_msg("filter offset:%f(corr:%e) disp:%f jitter:%f",
|
---|
592 | p->filter_offset, x,
|
---|
593 | p->filter_dispersion,
|
---|
594 | p->filter_jitter);
|
---|
595 | }
|
---|
596 |
|
---|
597 | static void
|
---|
598 | reset_peer_stats(peer_t *p, double offset)
|
---|
599 | {
|
---|
600 | int i;
|
---|
601 | bool small_ofs = fabs(offset) < 16 * STEP_THRESHOLD;
|
---|
602 |
|
---|
603 | for (i = 0; i < NUM_DATAPOINTS; i++) {
|
---|
604 | if (small_ofs) {
|
---|
605 | p->filter_datapoint[i].d_recv_time += offset;
|
---|
606 | if (p->filter_datapoint[i].d_offset != 0) {
|
---|
607 | p->filter_datapoint[i].d_offset += offset;
|
---|
608 | }
|
---|
609 | } else {
|
---|
610 | p->filter_datapoint[i].d_recv_time = G.cur_time;
|
---|
611 | p->filter_datapoint[i].d_offset = 0;
|
---|
612 | p->filter_datapoint[i].d_dispersion = MAXDISP;
|
---|
613 | }
|
---|
614 | }
|
---|
615 | if (small_ofs) {
|
---|
616 | p->lastpkt_recv_time += offset;
|
---|
617 | } else {
|
---|
618 | p->reachable_bits = 0;
|
---|
619 | p->lastpkt_recv_time = G.cur_time;
|
---|
620 | }
|
---|
621 | filter_datapoints(p); /* recalc p->filter_xxx */
|
---|
622 | VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
|
---|
623 | }
|
---|
624 |
|
---|
625 | static void
|
---|
626 | add_peers(char *s)
|
---|
627 | {
|
---|
628 | peer_t *p;
|
---|
629 |
|
---|
630 | p = xzalloc(sizeof(*p));
|
---|
631 | p->p_lsa = xhost2sockaddr(s, 123);
|
---|
632 | p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
|
---|
633 | p->p_fd = -1;
|
---|
634 | p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
|
---|
635 | p->next_action_time = G.cur_time; /* = set_next(p, 0); */
|
---|
636 | reset_peer_stats(p, 16 * STEP_THRESHOLD);
|
---|
637 |
|
---|
638 | llist_add_to(&G.ntp_peers, p);
|
---|
639 | G.peer_cnt++;
|
---|
640 | }
|
---|
641 |
|
---|
642 | static int
|
---|
643 | do_sendto(int fd,
|
---|
644 | const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
|
---|
645 | msg_t *msg, ssize_t len)
|
---|
646 | {
|
---|
647 | ssize_t ret;
|
---|
648 |
|
---|
649 | errno = 0;
|
---|
650 | if (!from) {
|
---|
651 | ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
|
---|
652 | } else {
|
---|
653 | ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
|
---|
654 | }
|
---|
655 | if (ret != len) {
|
---|
656 | bb_perror_msg("send failed");
|
---|
657 | return -1;
|
---|
658 | }
|
---|
659 | return 0;
|
---|
660 | }
|
---|
661 |
|
---|
662 | static void
|
---|
663 | send_query_to_peer(peer_t *p)
|
---|
664 | {
|
---|
665 | /* Why do we need to bind()?
|
---|
666 | * See what happens when we don't bind:
|
---|
667 | *
|
---|
668 | * socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
|
---|
669 | * setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
|
---|
670 | * gettimeofday({1259071266, 327885}, NULL) = 0
|
---|
671 | * sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
|
---|
672 | * ^^^ we sent it from some source port picked by kernel.
|
---|
673 | * time(NULL) = 1259071266
|
---|
674 | * write(2, "ntpd: entering poll 15 secs\n", 28) = 28
|
---|
675 | * poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
|
---|
676 | * recv(3, "yyy", 68, MSG_DONTWAIT) = 48
|
---|
677 | * ^^^ this recv will receive packets to any local port!
|
---|
678 | *
|
---|
679 | * Uncomment this and use strace to see it in action:
|
---|
680 | */
|
---|
681 | #define PROBE_LOCAL_ADDR /* { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } */
|
---|
682 |
|
---|
683 | if (p->p_fd == -1) {
|
---|
684 | int fd, family;
|
---|
685 | len_and_sockaddr *local_lsa;
|
---|
686 |
|
---|
687 | family = p->p_lsa->u.sa.sa_family;
|
---|
688 | p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
|
---|
689 | /* local_lsa has "null" address and port 0 now.
|
---|
690 | * bind() ensures we have a *particular port* selected by kernel
|
---|
691 | * and remembered in p->p_fd, thus later recv(p->p_fd)
|
---|
692 | * receives only packets sent to this port.
|
---|
693 | */
|
---|
694 | PROBE_LOCAL_ADDR
|
---|
695 | xbind(fd, &local_lsa->u.sa, local_lsa->len);
|
---|
696 | PROBE_LOCAL_ADDR
|
---|
697 | #if ENABLE_FEATURE_IPV6
|
---|
698 | if (family == AF_INET)
|
---|
699 | #endif
|
---|
700 | setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
|
---|
701 | free(local_lsa);
|
---|
702 | }
|
---|
703 |
|
---|
704 | /*
|
---|
705 | * Send out a random 64-bit number as our transmit time. The NTP
|
---|
706 | * server will copy said number into the originate field on the
|
---|
707 | * response that it sends us. This is totally legal per the SNTP spec.
|
---|
708 | *
|
---|
709 | * The impact of this is two fold: we no longer send out the current
|
---|
710 | * system time for the world to see (which may aid an attacker), and
|
---|
711 | * it gives us a (not very secure) way of knowing that we're not
|
---|
712 | * getting spoofed by an attacker that can't capture our traffic
|
---|
713 | * but can spoof packets from the NTP server we're communicating with.
|
---|
714 | *
|
---|
715 | * Save the real transmit timestamp locally.
|
---|
716 | */
|
---|
717 | p->p_xmt_msg.m_xmttime.int_partl = random();
|
---|
718 | p->p_xmt_msg.m_xmttime.fractionl = random();
|
---|
719 | p->p_xmttime = gettime1900d();
|
---|
720 |
|
---|
721 | if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
|
---|
722 | &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
|
---|
723 | ) {
|
---|
724 | close(p->p_fd);
|
---|
725 | p->p_fd = -1;
|
---|
726 | set_next(p, RETRY_INTERVAL);
|
---|
727 | return;
|
---|
728 | }
|
---|
729 |
|
---|
730 | p->reachable_bits <<= 1;
|
---|
731 | VERB1 bb_error_msg("sent query to %s", p->p_dotted);
|
---|
732 | set_next(p, RESPONSE_INTERVAL);
|
---|
733 | }
|
---|
734 |
|
---|
735 |
|
---|
736 | /* Note that there is no provision to prevent several run_scripts
|
---|
737 | * to be done in quick succession. In fact, it happens rather often
|
---|
738 | * if initial syncronization results in a step.
|
---|
739 | * You will see "step" and then "stratum" script runs, sometimes
|
---|
740 | * as close as only 0.002 seconds apart.
|
---|
741 | * Script should be ready to deal with this.
|
---|
742 | */
|
---|
743 | static void run_script(const char *action, double offset)
|
---|
744 | {
|
---|
745 | char *argv[3];
|
---|
746 | char *env1, *env2, *env3, *env4;
|
---|
747 |
|
---|
748 | if (!G.script_name)
|
---|
749 | return;
|
---|
750 |
|
---|
751 | argv[0] = (char*) G.script_name;
|
---|
752 | argv[1] = (char*) action;
|
---|
753 | argv[2] = NULL;
|
---|
754 |
|
---|
755 | VERB1 bb_error_msg("executing '%s %s'", G.script_name, action);
|
---|
756 |
|
---|
757 | env1 = xasprintf("%s=%u", "stratum", G.stratum);
|
---|
758 | putenv(env1);
|
---|
759 | env2 = xasprintf("%s=%ld", "freq_drift_ppm", G.kernel_freq_drift);
|
---|
760 | putenv(env2);
|
---|
761 | env3 = xasprintf("%s=%u", "poll_interval", 1 << G.poll_exp);
|
---|
762 | putenv(env3);
|
---|
763 | env4 = xasprintf("%s=%f", "offset", offset);
|
---|
764 | putenv(env4);
|
---|
765 | /* Other items of potential interest: selected peer,
|
---|
766 | * rootdelay, reftime, rootdisp, refid, ntp_status,
|
---|
767 | * last_update_offset, last_update_recv_time, discipline_jitter,
|
---|
768 | * how many peers have reachable_bits = 0?
|
---|
769 | */
|
---|
770 |
|
---|
771 | /* Don't want to wait: it may run hwclock --systohc, and that
|
---|
772 | * may take some time (seconds): */
|
---|
773 | /*spawn_and_wait(argv);*/
|
---|
774 | spawn(argv);
|
---|
775 |
|
---|
776 | unsetenv("stratum");
|
---|
777 | unsetenv("freq_drift_ppm");
|
---|
778 | unsetenv("poll_interval");
|
---|
779 | unsetenv("offset");
|
---|
780 | free(env1);
|
---|
781 | free(env2);
|
---|
782 | free(env3);
|
---|
783 | free(env4);
|
---|
784 |
|
---|
785 | G.last_script_run = G.cur_time;
|
---|
786 | }
|
---|
787 |
|
---|
788 | static NOINLINE void
|
---|
789 | step_time(double offset)
|
---|
790 | {
|
---|
791 | llist_t *item;
|
---|
792 | double dtime;
|
---|
793 | struct timeval tv;
|
---|
794 | char buf[80];
|
---|
795 | time_t tval;
|
---|
796 |
|
---|
797 | gettimeofday(&tv, NULL); /* never fails */
|
---|
798 | dtime = offset + tv.tv_sec;
|
---|
799 | dtime += 1.0e-6 * tv.tv_usec;
|
---|
800 | d_to_tv(dtime, &tv);
|
---|
801 |
|
---|
802 | if (settimeofday(&tv, NULL) == -1)
|
---|
803 | bb_perror_msg_and_die("settimeofday");
|
---|
804 |
|
---|
805 | tval = tv.tv_sec;
|
---|
806 | strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
|
---|
807 |
|
---|
808 | bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
|
---|
809 |
|
---|
810 | /* Correct various fields which contain time-relative values: */
|
---|
811 |
|
---|
812 | /* p->lastpkt_recv_time, p->next_action_time and such: */
|
---|
813 | for (item = G.ntp_peers; item != NULL; item = item->link) {
|
---|
814 | peer_t *pp = (peer_t *) item->data;
|
---|
815 | reset_peer_stats(pp, offset);
|
---|
816 | //bb_error_msg("offset:%f pp->next_action_time:%f -> %f",
|
---|
817 | // offset, pp->next_action_time, pp->next_action_time + offset);
|
---|
818 | pp->next_action_time += offset;
|
---|
819 | }
|
---|
820 | /* Globals: */
|
---|
821 | G.cur_time += offset;
|
---|
822 | G.last_update_recv_time += offset;
|
---|
823 | G.last_script_run += offset;
|
---|
824 | }
|
---|
825 |
|
---|
826 |
|
---|
827 | /*
|
---|
828 | * Selection and clustering, and their helpers
|
---|
829 | */
|
---|
830 | typedef struct {
|
---|
831 | peer_t *p;
|
---|
832 | int type;
|
---|
833 | double edge;
|
---|
834 | double opt_rd; /* optimization */
|
---|
835 | } point_t;
|
---|
836 | static int
|
---|
837 | compare_point_edge(const void *aa, const void *bb)
|
---|
838 | {
|
---|
839 | const point_t *a = aa;
|
---|
840 | const point_t *b = bb;
|
---|
841 | if (a->edge < b->edge) {
|
---|
842 | return -1;
|
---|
843 | }
|
---|
844 | return (a->edge > b->edge);
|
---|
845 | }
|
---|
846 | typedef struct {
|
---|
847 | peer_t *p;
|
---|
848 | double metric;
|
---|
849 | } survivor_t;
|
---|
850 | static int
|
---|
851 | compare_survivor_metric(const void *aa, const void *bb)
|
---|
852 | {
|
---|
853 | const survivor_t *a = aa;
|
---|
854 | const survivor_t *b = bb;
|
---|
855 | if (a->metric < b->metric) {
|
---|
856 | return -1;
|
---|
857 | }
|
---|
858 | return (a->metric > b->metric);
|
---|
859 | }
|
---|
860 | static int
|
---|
861 | fit(peer_t *p, double rd)
|
---|
862 | {
|
---|
863 | if ((p->reachable_bits & (p->reachable_bits-1)) == 0) {
|
---|
864 | /* One or zero bits in reachable_bits */
|
---|
865 | VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
|
---|
866 | return 0;
|
---|
867 | }
|
---|
868 | #if 0 /* we filter out such packets earlier */
|
---|
869 | if ((p->lastpkt_status & LI_ALARM) == LI_ALARM
|
---|
870 | || p->lastpkt_stratum >= MAXSTRAT
|
---|
871 | ) {
|
---|
872 | VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
|
---|
873 | return 0;
|
---|
874 | }
|
---|
875 | #endif
|
---|
876 | /* rd is root_distance(p) */
|
---|
877 | if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
|
---|
878 | VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
|
---|
879 | return 0;
|
---|
880 | }
|
---|
881 | //TODO
|
---|
882 | // /* Do we have a loop? */
|
---|
883 | // if (p->refid == p->dstaddr || p->refid == s.refid)
|
---|
884 | // return 0;
|
---|
885 | return 1;
|
---|
886 | }
|
---|
887 | static peer_t*
|
---|
888 | select_and_cluster(void)
|
---|
889 | {
|
---|
890 | peer_t *p;
|
---|
891 | llist_t *item;
|
---|
892 | int i, j;
|
---|
893 | int size = 3 * G.peer_cnt;
|
---|
894 | /* for selection algorithm */
|
---|
895 | point_t point[size];
|
---|
896 | unsigned num_points, num_candidates;
|
---|
897 | double low, high;
|
---|
898 | unsigned num_falsetickers;
|
---|
899 | /* for cluster algorithm */
|
---|
900 | survivor_t survivor[size];
|
---|
901 | unsigned num_survivors;
|
---|
902 |
|
---|
903 | /* Selection */
|
---|
904 |
|
---|
905 | num_points = 0;
|
---|
906 | item = G.ntp_peers;
|
---|
907 | if (G.initial_poll_complete) while (item != NULL) {
|
---|
908 | double rd, offset;
|
---|
909 |
|
---|
910 | p = (peer_t *) item->data;
|
---|
911 | rd = root_distance(p);
|
---|
912 | offset = p->filter_offset;
|
---|
913 | if (!fit(p, rd)) {
|
---|
914 | item = item->link;
|
---|
915 | continue;
|
---|
916 | }
|
---|
917 |
|
---|
918 | VERB4 bb_error_msg("interval: [%f %f %f] %s",
|
---|
919 | offset - rd,
|
---|
920 | offset,
|
---|
921 | offset + rd,
|
---|
922 | p->p_dotted
|
---|
923 | );
|
---|
924 | point[num_points].p = p;
|
---|
925 | point[num_points].type = -1;
|
---|
926 | point[num_points].edge = offset - rd;
|
---|
927 | point[num_points].opt_rd = rd;
|
---|
928 | num_points++;
|
---|
929 | point[num_points].p = p;
|
---|
930 | point[num_points].type = 0;
|
---|
931 | point[num_points].edge = offset;
|
---|
932 | point[num_points].opt_rd = rd;
|
---|
933 | num_points++;
|
---|
934 | point[num_points].p = p;
|
---|
935 | point[num_points].type = 1;
|
---|
936 | point[num_points].edge = offset + rd;
|
---|
937 | point[num_points].opt_rd = rd;
|
---|
938 | num_points++;
|
---|
939 | item = item->link;
|
---|
940 | }
|
---|
941 | num_candidates = num_points / 3;
|
---|
942 | if (num_candidates == 0) {
|
---|
943 | VERB3 bb_error_msg("no valid datapoints, no peer selected");
|
---|
944 | return NULL;
|
---|
945 | }
|
---|
946 | //TODO: sorting does not seem to be done in reference code
|
---|
947 | qsort(point, num_points, sizeof(point[0]), compare_point_edge);
|
---|
948 |
|
---|
949 | /* Start with the assumption that there are no falsetickers.
|
---|
950 | * Attempt to find a nonempty intersection interval containing
|
---|
951 | * the midpoints of all truechimers.
|
---|
952 | * If a nonempty interval cannot be found, increase the number
|
---|
953 | * of assumed falsetickers by one and try again.
|
---|
954 | * If a nonempty interval is found and the number of falsetickers
|
---|
955 | * is less than the number of truechimers, a majority has been found
|
---|
956 | * and the midpoint of each truechimer represents
|
---|
957 | * the candidates available to the cluster algorithm.
|
---|
958 | */
|
---|
959 | num_falsetickers = 0;
|
---|
960 | while (1) {
|
---|
961 | int c;
|
---|
962 | unsigned num_midpoints = 0;
|
---|
963 |
|
---|
964 | low = 1 << 9;
|
---|
965 | high = - (1 << 9);
|
---|
966 | c = 0;
|
---|
967 | for (i = 0; i < num_points; i++) {
|
---|
968 | /* We want to do:
|
---|
969 | * if (point[i].type == -1) c++;
|
---|
970 | * if (point[i].type == 1) c--;
|
---|
971 | * and it's simpler to do it this way:
|
---|
972 | */
|
---|
973 | c -= point[i].type;
|
---|
974 | if (c >= num_candidates - num_falsetickers) {
|
---|
975 | /* If it was c++ and it got big enough... */
|
---|
976 | low = point[i].edge;
|
---|
977 | break;
|
---|
978 | }
|
---|
979 | if (point[i].type == 0)
|
---|
980 | num_midpoints++;
|
---|
981 | }
|
---|
982 | c = 0;
|
---|
983 | for (i = num_points-1; i >= 0; i--) {
|
---|
984 | c += point[i].type;
|
---|
985 | if (c >= num_candidates - num_falsetickers) {
|
---|
986 | high = point[i].edge;
|
---|
987 | break;
|
---|
988 | }
|
---|
989 | if (point[i].type == 0)
|
---|
990 | num_midpoints++;
|
---|
991 | }
|
---|
992 | /* If the number of midpoints is greater than the number
|
---|
993 | * of allowed falsetickers, the intersection contains at
|
---|
994 | * least one truechimer with no midpoint - bad.
|
---|
995 | * Also, interval should be nonempty.
|
---|
996 | */
|
---|
997 | if (num_midpoints <= num_falsetickers && low < high)
|
---|
998 | break;
|
---|
999 | num_falsetickers++;
|
---|
1000 | if (num_falsetickers * 2 >= num_candidates) {
|
---|
1001 | VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected",
|
---|
1002 | num_falsetickers, num_candidates);
|
---|
1003 | return NULL;
|
---|
1004 | }
|
---|
1005 | }
|
---|
1006 | VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d",
|
---|
1007 | low, high, num_candidates, num_falsetickers);
|
---|
1008 |
|
---|
1009 | /* Clustering */
|
---|
1010 |
|
---|
1011 | /* Construct a list of survivors (p, metric)
|
---|
1012 | * from the chime list, where metric is dominated
|
---|
1013 | * first by stratum and then by root distance.
|
---|
1014 | * All other things being equal, this is the order of preference.
|
---|
1015 | */
|
---|
1016 | num_survivors = 0;
|
---|
1017 | for (i = 0; i < num_points; i++) {
|
---|
1018 | if (point[i].edge < low || point[i].edge > high)
|
---|
1019 | continue;
|
---|
1020 | p = point[i].p;
|
---|
1021 | survivor[num_survivors].p = p;
|
---|
1022 | /* x.opt_rd == root_distance(p); */
|
---|
1023 | survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + point[i].opt_rd;
|
---|
1024 | VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s",
|
---|
1025 | num_survivors, survivor[num_survivors].metric, p->p_dotted);
|
---|
1026 | num_survivors++;
|
---|
1027 | }
|
---|
1028 | /* There must be at least MIN_SELECTED survivors to satisfy the
|
---|
1029 | * correctness assertions. Ordinarily, the Byzantine criteria
|
---|
1030 | * require four survivors, but for the demonstration here, one
|
---|
1031 | * is acceptable.
|
---|
1032 | */
|
---|
1033 | if (num_survivors < MIN_SELECTED) {
|
---|
1034 | VERB3 bb_error_msg("num_survivors %d < %d, no peer selected",
|
---|
1035 | num_survivors, MIN_SELECTED);
|
---|
1036 | return NULL;
|
---|
1037 | }
|
---|
1038 |
|
---|
1039 | //looks like this is ONLY used by the fact that later we pick survivor[0].
|
---|
1040 | //we can avoid sorting then, just find the minimum once!
|
---|
1041 | qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric);
|
---|
1042 |
|
---|
1043 | /* For each association p in turn, calculate the selection
|
---|
1044 | * jitter p->sjitter as the square root of the sum of squares
|
---|
1045 | * (p->offset - q->offset) over all q associations. The idea is
|
---|
1046 | * to repeatedly discard the survivor with maximum selection
|
---|
1047 | * jitter until a termination condition is met.
|
---|
1048 | */
|
---|
1049 | while (1) {
|
---|
1050 | unsigned max_idx = max_idx;
|
---|
1051 | double max_selection_jitter = max_selection_jitter;
|
---|
1052 | double min_jitter = min_jitter;
|
---|
1053 |
|
---|
1054 | if (num_survivors <= MIN_CLUSTERED) {
|
---|
1055 | VERB3 bb_error_msg("num_survivors %d <= %d, not discarding more",
|
---|
1056 | num_survivors, MIN_CLUSTERED);
|
---|
1057 | break;
|
---|
1058 | }
|
---|
1059 |
|
---|
1060 | /* To make sure a few survivors are left
|
---|
1061 | * for the clustering algorithm to chew on,
|
---|
1062 | * we stop if the number of survivors
|
---|
1063 | * is less than or equal to MIN_CLUSTERED (3).
|
---|
1064 | */
|
---|
1065 | for (i = 0; i < num_survivors; i++) {
|
---|
1066 | double selection_jitter_sq;
|
---|
1067 |
|
---|
1068 | p = survivor[i].p;
|
---|
1069 | if (i == 0 || p->filter_jitter < min_jitter)
|
---|
1070 | min_jitter = p->filter_jitter;
|
---|
1071 |
|
---|
1072 | selection_jitter_sq = 0;
|
---|
1073 | for (j = 0; j < num_survivors; j++) {
|
---|
1074 | peer_t *q = survivor[j].p;
|
---|
1075 | selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
|
---|
1076 | }
|
---|
1077 | if (i == 0 || selection_jitter_sq > max_selection_jitter) {
|
---|
1078 | max_selection_jitter = selection_jitter_sq;
|
---|
1079 | max_idx = i;
|
---|
1080 | }
|
---|
1081 | VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
|
---|
1082 | i, selection_jitter_sq);
|
---|
1083 | }
|
---|
1084 | max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
|
---|
1085 | VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
|
---|
1086 | max_idx, max_selection_jitter, min_jitter);
|
---|
1087 |
|
---|
1088 | /* If the maximum selection jitter is less than the
|
---|
1089 | * minimum peer jitter, then tossing out more survivors
|
---|
1090 | * will not lower the minimum peer jitter, so we might
|
---|
1091 | * as well stop.
|
---|
1092 | */
|
---|
1093 | if (max_selection_jitter < min_jitter) {
|
---|
1094 | VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more",
|
---|
1095 | max_selection_jitter, min_jitter, num_survivors);
|
---|
1096 | break;
|
---|
1097 | }
|
---|
1098 |
|
---|
1099 | /* Delete survivor[max_idx] from the list
|
---|
1100 | * and go around again.
|
---|
1101 | */
|
---|
1102 | VERB5 bb_error_msg("dropping survivor %d", max_idx);
|
---|
1103 | num_survivors--;
|
---|
1104 | while (max_idx < num_survivors) {
|
---|
1105 | survivor[max_idx] = survivor[max_idx + 1];
|
---|
1106 | max_idx++;
|
---|
1107 | }
|
---|
1108 | }
|
---|
1109 |
|
---|
1110 | if (0) {
|
---|
1111 | /* Combine the offsets of the clustering algorithm survivors
|
---|
1112 | * using a weighted average with weight determined by the root
|
---|
1113 | * distance. Compute the selection jitter as the weighted RMS
|
---|
1114 | * difference between the first survivor and the remaining
|
---|
1115 | * survivors. In some cases the inherent clock jitter can be
|
---|
1116 | * reduced by not using this algorithm, especially when frequent
|
---|
1117 | * clockhopping is involved. bbox: thus we don't do it.
|
---|
1118 | */
|
---|
1119 | double x, y, z, w;
|
---|
1120 | y = z = w = 0;
|
---|
1121 | for (i = 0; i < num_survivors; i++) {
|
---|
1122 | p = survivor[i].p;
|
---|
1123 | x = root_distance(p);
|
---|
1124 | y += 1 / x;
|
---|
1125 | z += p->filter_offset / x;
|
---|
1126 | w += SQUARE(p->filter_offset - survivor[0].p->filter_offset) / x;
|
---|
1127 | }
|
---|
1128 | //G.cluster_offset = z / y;
|
---|
1129 | //G.cluster_jitter = SQRT(w / y);
|
---|
1130 | }
|
---|
1131 |
|
---|
1132 | /* Pick the best clock. If the old system peer is on the list
|
---|
1133 | * and at the same stratum as the first survivor on the list,
|
---|
1134 | * then don't do a clock hop. Otherwise, select the first
|
---|
1135 | * survivor on the list as the new system peer.
|
---|
1136 | */
|
---|
1137 | p = survivor[0].p;
|
---|
1138 | if (G.last_update_peer
|
---|
1139 | && G.last_update_peer->lastpkt_stratum <= p->lastpkt_stratum
|
---|
1140 | ) {
|
---|
1141 | /* Starting from 1 is ok here */
|
---|
1142 | for (i = 1; i < num_survivors; i++) {
|
---|
1143 | if (G.last_update_peer == survivor[i].p) {
|
---|
1144 | VERB4 bb_error_msg("keeping old synced peer");
|
---|
1145 | p = G.last_update_peer;
|
---|
1146 | goto keep_old;
|
---|
1147 | }
|
---|
1148 | }
|
---|
1149 | }
|
---|
1150 | G.last_update_peer = p;
|
---|
1151 | keep_old:
|
---|
1152 | VERB3 bb_error_msg("selected peer %s filter_offset:%f age:%f",
|
---|
1153 | p->p_dotted,
|
---|
1154 | p->filter_offset,
|
---|
1155 | G.cur_time - p->lastpkt_recv_time
|
---|
1156 | );
|
---|
1157 | return p;
|
---|
1158 | }
|
---|
1159 |
|
---|
1160 |
|
---|
1161 | /*
|
---|
1162 | * Local clock discipline and its helpers
|
---|
1163 | */
|
---|
1164 | static void
|
---|
1165 | set_new_values(int disc_state, double offset, double recv_time)
|
---|
1166 | {
|
---|
1167 | /* Enter new state and set state variables. Note we use the time
|
---|
1168 | * of the last clock filter sample, which must be earlier than
|
---|
1169 | * the current time.
|
---|
1170 | */
|
---|
1171 | VERB3 bb_error_msg("disc_state=%d last update offset=%f recv_time=%f",
|
---|
1172 | disc_state, offset, recv_time);
|
---|
1173 | G.discipline_state = disc_state;
|
---|
1174 | G.last_update_offset = offset;
|
---|
1175 | G.last_update_recv_time = recv_time;
|
---|
1176 | }
|
---|
1177 | /* Return: -1: decrease poll interval, 0: leave as is, 1: increase */
|
---|
1178 | static NOINLINE int
|
---|
1179 | update_local_clock(peer_t *p)
|
---|
1180 | {
|
---|
1181 | int rc;
|
---|
1182 | struct timex tmx;
|
---|
1183 | /* Note: can use G.cluster_offset instead: */
|
---|
1184 | double offset = p->filter_offset;
|
---|
1185 | double recv_time = p->lastpkt_recv_time;
|
---|
1186 | double abs_offset;
|
---|
1187 | #if !USING_KERNEL_PLL_LOOP
|
---|
1188 | double freq_drift;
|
---|
1189 | #endif
|
---|
1190 | double since_last_update;
|
---|
1191 | double etemp, dtemp;
|
---|
1192 |
|
---|
1193 | abs_offset = fabs(offset);
|
---|
1194 |
|
---|
1195 | #if 0
|
---|
1196 | /* If needed, -S script can do it by looking at $offset
|
---|
1197 | * env var and killing parent */
|
---|
1198 | /* If the offset is too large, give up and go home */
|
---|
1199 | if (abs_offset > PANIC_THRESHOLD) {
|
---|
1200 | bb_error_msg_and_die("offset %f far too big, exiting", offset);
|
---|
1201 | }
|
---|
1202 | #endif
|
---|
1203 |
|
---|
1204 | /* If this is an old update, for instance as the result
|
---|
1205 | * of a system peer change, avoid it. We never use
|
---|
1206 | * an old sample or the same sample twice.
|
---|
1207 | */
|
---|
1208 | if (recv_time <= G.last_update_recv_time) {
|
---|
1209 | VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it",
|
---|
1210 | G.last_update_recv_time, recv_time);
|
---|
1211 | return 0; /* "leave poll interval as is" */
|
---|
1212 | }
|
---|
1213 |
|
---|
1214 | /* Clock state machine transition function. This is where the
|
---|
1215 | * action is and defines how the system reacts to large time
|
---|
1216 | * and frequency errors.
|
---|
1217 | */
|
---|
1218 | since_last_update = recv_time - G.reftime;
|
---|
1219 | #if !USING_KERNEL_PLL_LOOP
|
---|
1220 | freq_drift = 0;
|
---|
1221 | #endif
|
---|
1222 | #if USING_INITIAL_FREQ_ESTIMATION
|
---|
1223 | if (G.discipline_state == STATE_FREQ) {
|
---|
1224 | /* Ignore updates until the stepout threshold */
|
---|
1225 | if (since_last_update < WATCH_THRESHOLD) {
|
---|
1226 | VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains",
|
---|
1227 | WATCH_THRESHOLD - since_last_update);
|
---|
1228 | return 0; /* "leave poll interval as is" */
|
---|
1229 | }
|
---|
1230 | # if !USING_KERNEL_PLL_LOOP
|
---|
1231 | freq_drift = (offset - G.last_update_offset) / since_last_update;
|
---|
1232 | # endif
|
---|
1233 | }
|
---|
1234 | #endif
|
---|
1235 |
|
---|
1236 | /* There are two main regimes: when the
|
---|
1237 | * offset exceeds the step threshold and when it does not.
|
---|
1238 | */
|
---|
1239 | if (abs_offset > STEP_THRESHOLD) {
|
---|
1240 | switch (G.discipline_state) {
|
---|
1241 | case STATE_SYNC:
|
---|
1242 | /* The first outlyer: ignore it, switch to SPIK state */
|
---|
1243 | VERB3 bb_error_msg("offset:%f - spike detected", offset);
|
---|
1244 | G.discipline_state = STATE_SPIK;
|
---|
1245 | return -1; /* "decrease poll interval" */
|
---|
1246 |
|
---|
1247 | case STATE_SPIK:
|
---|
1248 | /* Ignore succeeding outlyers until either an inlyer
|
---|
1249 | * is found or the stepout threshold is exceeded.
|
---|
1250 | */
|
---|
1251 | if (since_last_update < WATCH_THRESHOLD) {
|
---|
1252 | VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains",
|
---|
1253 | WATCH_THRESHOLD - since_last_update);
|
---|
1254 | return -1; /* "decrease poll interval" */
|
---|
1255 | }
|
---|
1256 | /* fall through: we need to step */
|
---|
1257 | } /* switch */
|
---|
1258 |
|
---|
1259 | /* Step the time and clamp down the poll interval.
|
---|
1260 | *
|
---|
1261 | * In NSET state an initial frequency correction is
|
---|
1262 | * not available, usually because the frequency file has
|
---|
1263 | * not yet been written. Since the time is outside the
|
---|
1264 | * capture range, the clock is stepped. The frequency
|
---|
1265 | * will be set directly following the stepout interval.
|
---|
1266 | *
|
---|
1267 | * In FSET state the initial frequency has been set
|
---|
1268 | * from the frequency file. Since the time is outside
|
---|
1269 | * the capture range, the clock is stepped immediately,
|
---|
1270 | * rather than after the stepout interval. Guys get
|
---|
1271 | * nervous if it takes 17 minutes to set the clock for
|
---|
1272 | * the first time.
|
---|
1273 | *
|
---|
1274 | * In SPIK state the stepout threshold has expired and
|
---|
1275 | * the phase is still above the step threshold. Note
|
---|
1276 | * that a single spike greater than the step threshold
|
---|
1277 | * is always suppressed, even at the longer poll
|
---|
1278 | * intervals.
|
---|
1279 | */
|
---|
1280 | VERB3 bb_error_msg("stepping time by %f; poll_exp=MINPOLL", offset);
|
---|
1281 | step_time(offset);
|
---|
1282 | if (option_mask32 & OPT_q) {
|
---|
1283 | /* We were only asked to set time once. Done. */
|
---|
1284 | exit(0);
|
---|
1285 | }
|
---|
1286 |
|
---|
1287 | G.polladj_count = 0;
|
---|
1288 | G.poll_exp = MINPOLL;
|
---|
1289 | G.stratum = MAXSTRAT;
|
---|
1290 |
|
---|
1291 | run_script("step", offset);
|
---|
1292 |
|
---|
1293 | #if USING_INITIAL_FREQ_ESTIMATION
|
---|
1294 | if (G.discipline_state == STATE_NSET) {
|
---|
1295 | set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time);
|
---|
1296 | return 1; /* "ok to increase poll interval" */
|
---|
1297 | }
|
---|
1298 | #endif
|
---|
1299 | set_new_values(STATE_SYNC, /*offset:*/ 0, recv_time);
|
---|
1300 |
|
---|
1301 | } else { /* abs_offset <= STEP_THRESHOLD */
|
---|
1302 |
|
---|
1303 | if (G.poll_exp < MINPOLL && G.initial_poll_complete) {
|
---|
1304 | VERB3 bb_error_msg("small offset:%f, disabling burst mode", offset);
|
---|
1305 | G.polladj_count = 0;
|
---|
1306 | G.poll_exp = MINPOLL;
|
---|
1307 | }
|
---|
1308 |
|
---|
1309 | /* Compute the clock jitter as the RMS of exponentially
|
---|
1310 | * weighted offset differences. Used by the poll adjust code.
|
---|
1311 | */
|
---|
1312 | etemp = SQUARE(G.discipline_jitter);
|
---|
1313 | dtemp = SQUARE(MAXD(fabs(offset - G.last_update_offset), G_precision_sec));
|
---|
1314 | G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG);
|
---|
1315 | VERB3 bb_error_msg("discipline jitter=%f", G.discipline_jitter);
|
---|
1316 |
|
---|
1317 | switch (G.discipline_state) {
|
---|
1318 | case STATE_NSET:
|
---|
1319 | if (option_mask32 & OPT_q) {
|
---|
1320 | /* We were only asked to set time once.
|
---|
1321 | * The clock is precise enough, no need to step.
|
---|
1322 | */
|
---|
1323 | exit(0);
|
---|
1324 | }
|
---|
1325 | #if USING_INITIAL_FREQ_ESTIMATION
|
---|
1326 | /* This is the first update received and the frequency
|
---|
1327 | * has not been initialized. The first thing to do
|
---|
1328 | * is directly measure the oscillator frequency.
|
---|
1329 | */
|
---|
1330 | set_new_values(STATE_FREQ, offset, recv_time);
|
---|
1331 | #else
|
---|
1332 | set_new_values(STATE_SYNC, offset, recv_time);
|
---|
1333 | #endif
|
---|
1334 | VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored");
|
---|
1335 | return 0; /* "leave poll interval as is" */
|
---|
1336 |
|
---|
1337 | #if 0 /* this is dead code for now */
|
---|
1338 | case STATE_FSET:
|
---|
1339 | /* This is the first update and the frequency
|
---|
1340 | * has been initialized. Adjust the phase, but
|
---|
1341 | * don't adjust the frequency until the next update.
|
---|
1342 | */
|
---|
1343 | set_new_values(STATE_SYNC, offset, recv_time);
|
---|
1344 | /* freq_drift remains 0 */
|
---|
1345 | break;
|
---|
1346 | #endif
|
---|
1347 |
|
---|
1348 | #if USING_INITIAL_FREQ_ESTIMATION
|
---|
1349 | case STATE_FREQ:
|
---|
1350 | /* since_last_update >= WATCH_THRESHOLD, we waited enough.
|
---|
1351 | * Correct the phase and frequency and switch to SYNC state.
|
---|
1352 | * freq_drift was already estimated (see code above)
|
---|
1353 | */
|
---|
1354 | set_new_values(STATE_SYNC, offset, recv_time);
|
---|
1355 | break;
|
---|
1356 | #endif
|
---|
1357 |
|
---|
1358 | default:
|
---|
1359 | #if !USING_KERNEL_PLL_LOOP
|
---|
1360 | /* Compute freq_drift due to PLL and FLL contributions.
|
---|
1361 | *
|
---|
1362 | * The FLL and PLL frequency gain constants
|
---|
1363 | * depend on the poll interval and Allan
|
---|
1364 | * intercept. The FLL is not used below one-half
|
---|
1365 | * the Allan intercept. Above that the loop gain
|
---|
1366 | * increases in steps to 1 / AVG.
|
---|
1367 | */
|
---|
1368 | if ((1 << G.poll_exp) > ALLAN / 2) {
|
---|
1369 | etemp = FLL - G.poll_exp;
|
---|
1370 | if (etemp < AVG)
|
---|
1371 | etemp = AVG;
|
---|
1372 | freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp);
|
---|
1373 | }
|
---|
1374 | /* For the PLL the integration interval
|
---|
1375 | * (numerator) is the minimum of the update
|
---|
1376 | * interval and poll interval. This allows
|
---|
1377 | * oversampling, but not undersampling.
|
---|
1378 | */
|
---|
1379 | etemp = MIND(since_last_update, (1 << G.poll_exp));
|
---|
1380 | dtemp = (4 * PLL) << G.poll_exp;
|
---|
1381 | freq_drift += offset * etemp / SQUARE(dtemp);
|
---|
1382 | #endif
|
---|
1383 | set_new_values(STATE_SYNC, offset, recv_time);
|
---|
1384 | break;
|
---|
1385 | }
|
---|
1386 | if (G.stratum != p->lastpkt_stratum + 1) {
|
---|
1387 | G.stratum = p->lastpkt_stratum + 1;
|
---|
1388 | run_script("stratum", offset);
|
---|
1389 | }
|
---|
1390 | }
|
---|
1391 |
|
---|
1392 | G.reftime = G.cur_time;
|
---|
1393 | G.ntp_status = p->lastpkt_status;
|
---|
1394 | G.refid = p->lastpkt_refid;
|
---|
1395 | G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
|
---|
1396 | dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(G.cluster_jitter));
|
---|
1397 | dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (G.cur_time - p->lastpkt_recv_time) + abs_offset, MINDISP);
|
---|
1398 | G.rootdisp = p->lastpkt_rootdisp + dtemp;
|
---|
1399 | VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted);
|
---|
1400 |
|
---|
1401 | /* We are in STATE_SYNC now, but did not do adjtimex yet.
|
---|
1402 | * (Any other state does not reach this, they all return earlier)
|
---|
1403 | * By this time, freq_drift and G.last_update_offset are set
|
---|
1404 | * to values suitable for adjtimex.
|
---|
1405 | */
|
---|
1406 | #if !USING_KERNEL_PLL_LOOP
|
---|
1407 | /* Calculate the new frequency drift and frequency stability (wander).
|
---|
1408 | * Compute the clock wander as the RMS of exponentially weighted
|
---|
1409 | * frequency differences. This is not used directly, but can,
|
---|
1410 | * along with the jitter, be a highly useful monitoring and
|
---|
1411 | * debugging tool.
|
---|
1412 | */
|
---|
1413 | dtemp = G.discipline_freq_drift + freq_drift;
|
---|
1414 | G.discipline_freq_drift = MAXD(MIND(MAXDRIFT, dtemp), -MAXDRIFT);
|
---|
1415 | etemp = SQUARE(G.discipline_wander);
|
---|
1416 | dtemp = SQUARE(dtemp);
|
---|
1417 | G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
|
---|
1418 |
|
---|
1419 | VERB3 bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
|
---|
1420 | G.discipline_freq_drift,
|
---|
1421 | (long)(G.discipline_freq_drift * 65536e6),
|
---|
1422 | freq_drift,
|
---|
1423 | G.discipline_wander);
|
---|
1424 | #endif
|
---|
1425 | VERB3 {
|
---|
1426 | memset(&tmx, 0, sizeof(tmx));
|
---|
1427 | if (adjtimex(&tmx) < 0)
|
---|
1428 | bb_perror_msg_and_die("adjtimex");
|
---|
1429 | VERB3 bb_error_msg("p adjtimex freq:%ld offset:%ld constant:%ld status:0x%x",
|
---|
1430 | tmx.freq, tmx.offset, tmx.constant, tmx.status);
|
---|
1431 | }
|
---|
1432 |
|
---|
1433 | memset(&tmx, 0, sizeof(tmx));
|
---|
1434 | #if 0
|
---|
1435 | //doesn't work, offset remains 0 (!) in kernel:
|
---|
1436 | //ntpd: set adjtimex freq:1786097 tmx.offset:77487
|
---|
1437 | //ntpd: prev adjtimex freq:1786097 tmx.offset:0
|
---|
1438 | //ntpd: cur adjtimex freq:1786097 tmx.offset:0
|
---|
1439 | tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET;
|
---|
1440 | /* 65536 is one ppm */
|
---|
1441 | tmx.freq = G.discipline_freq_drift * 65536e6;
|
---|
1442 | tmx.offset = G.last_update_offset * 1000000; /* usec */
|
---|
1443 | #endif
|
---|
1444 | tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR;
|
---|
1445 | tmx.offset = (G.last_update_offset * 1000000); /* usec */
|
---|
1446 | /* + (G.last_update_offset < 0 ? -0.5 : 0.5) - too small to bother */
|
---|
1447 | tmx.status = STA_PLL;
|
---|
1448 | if (G.ntp_status & LI_PLUSSEC)
|
---|
1449 | tmx.status |= STA_INS;
|
---|
1450 | if (G.ntp_status & LI_MINUSSEC)
|
---|
1451 | tmx.status |= STA_DEL;
|
---|
1452 | tmx.constant = G.poll_exp - 4;
|
---|
1453 | //tmx.esterror = (u_int32)(clock_jitter * 1e6);
|
---|
1454 | //tmx.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
|
---|
1455 | rc = adjtimex(&tmx);
|
---|
1456 | if (rc < 0)
|
---|
1457 | bb_perror_msg_and_die("adjtimex");
|
---|
1458 | /* NB: here kernel returns constant == G.poll_exp, not == G.poll_exp - 4.
|
---|
1459 | * Not sure why. Perhaps it is normal.
|
---|
1460 | */
|
---|
1461 | VERB3 bb_error_msg("adjtimex:%d freq:%ld offset:%ld constant:%ld status:0x%x",
|
---|
1462 | rc, tmx.freq, tmx.offset, tmx.constant, tmx.status);
|
---|
1463 | #if 0
|
---|
1464 | VERB3 {
|
---|
1465 | /* always gives the same output as above msg */
|
---|
1466 | memset(&tmx, 0, sizeof(tmx));
|
---|
1467 | if (adjtimex(&tmx) < 0)
|
---|
1468 | bb_perror_msg_and_die("adjtimex");
|
---|
1469 | VERB3 bb_error_msg("c adjtimex freq:%ld offset:%ld constant:%ld status:0x%x",
|
---|
1470 | tmx.freq, tmx.offset, tmx.constant, tmx.status);
|
---|
1471 | }
|
---|
1472 | #endif
|
---|
1473 | G.kernel_freq_drift = tmx.freq / 65536;
|
---|
1474 | VERB2 bb_error_msg("update peer:%s, offset:%f, clock drift:%ld ppm",
|
---|
1475 | p->p_dotted, G.last_update_offset, G.kernel_freq_drift);
|
---|
1476 |
|
---|
1477 | return 1; /* "ok to increase poll interval" */
|
---|
1478 | }
|
---|
1479 |
|
---|
1480 |
|
---|
1481 | /*
|
---|
1482 | * We've got a new reply packet from a peer, process it
|
---|
1483 | * (helpers first)
|
---|
1484 | */
|
---|
1485 | static unsigned
|
---|
1486 | retry_interval(void)
|
---|
1487 | {
|
---|
1488 | /* Local problem, want to retry soon */
|
---|
1489 | unsigned interval, r;
|
---|
1490 | interval = RETRY_INTERVAL;
|
---|
1491 | r = random();
|
---|
1492 | interval += r % (unsigned)(RETRY_INTERVAL / 4);
|
---|
1493 | VERB3 bb_error_msg("chose retry interval:%u", interval);
|
---|
1494 | return interval;
|
---|
1495 | }
|
---|
1496 | static unsigned
|
---|
1497 | poll_interval(int exponent)
|
---|
1498 | {
|
---|
1499 | unsigned interval, r;
|
---|
1500 | exponent = G.poll_exp + exponent;
|
---|
1501 | if (exponent < 0)
|
---|
1502 | exponent = 0;
|
---|
1503 | interval = 1 << exponent;
|
---|
1504 | r = random();
|
---|
1505 | interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */
|
---|
1506 | VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent);
|
---|
1507 | return interval;
|
---|
1508 | }
|
---|
1509 | static NOINLINE void
|
---|
1510 | recv_and_process_peer_pkt(peer_t *p)
|
---|
1511 | {
|
---|
1512 | int rc;
|
---|
1513 | ssize_t size;
|
---|
1514 | msg_t msg;
|
---|
1515 | double T1, T2, T3, T4;
|
---|
1516 | unsigned interval;
|
---|
1517 | datapoint_t *datapoint;
|
---|
1518 | peer_t *q;
|
---|
1519 |
|
---|
1520 | /* We can recvfrom here and check from.IP, but some multihomed
|
---|
1521 | * ntp servers reply from their *other IP*.
|
---|
1522 | * TODO: maybe we should check at least what we can: from.port == 123?
|
---|
1523 | */
|
---|
1524 | size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
|
---|
1525 | if (size == -1) {
|
---|
1526 | bb_perror_msg("recv(%s) error", p->p_dotted);
|
---|
1527 | if (errno == EHOSTUNREACH || errno == EHOSTDOWN
|
---|
1528 | || errno == ENETUNREACH || errno == ENETDOWN
|
---|
1529 | || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
|
---|
1530 | || errno == EAGAIN
|
---|
1531 | ) {
|
---|
1532 | //TODO: always do this?
|
---|
1533 | interval = retry_interval();
|
---|
1534 | goto set_next_and_close_sock;
|
---|
1535 | }
|
---|
1536 | xfunc_die();
|
---|
1537 | }
|
---|
1538 |
|
---|
1539 | if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
|
---|
1540 | bb_error_msg("malformed packet received from %s", p->p_dotted);
|
---|
1541 | goto bail;
|
---|
1542 | }
|
---|
1543 |
|
---|
1544 | if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
|
---|
1545 | || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
|
---|
1546 | ) {
|
---|
1547 | goto bail;
|
---|
1548 | }
|
---|
1549 |
|
---|
1550 | if ((msg.m_status & LI_ALARM) == LI_ALARM
|
---|
1551 | || msg.m_stratum == 0
|
---|
1552 | || msg.m_stratum > NTP_MAXSTRATUM
|
---|
1553 | ) {
|
---|
1554 | // TODO: stratum 0 responses may have commands in 32-bit m_refid field:
|
---|
1555 | // "DENY", "RSTR" - peer does not like us at all
|
---|
1556 | // "RATE" - peer is overloaded, reduce polling freq
|
---|
1557 | interval = poll_interval(0);
|
---|
1558 | bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
|
---|
1559 | goto set_next_and_close_sock;
|
---|
1560 | }
|
---|
1561 |
|
---|
1562 | // /* Verify valid root distance */
|
---|
1563 | // if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
|
---|
1564 | // return; /* invalid header values */
|
---|
1565 |
|
---|
1566 | p->lastpkt_status = msg.m_status;
|
---|
1567 | p->lastpkt_stratum = msg.m_stratum;
|
---|
1568 | p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
|
---|
1569 | p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
|
---|
1570 | p->lastpkt_refid = msg.m_refid;
|
---|
1571 |
|
---|
1572 | /*
|
---|
1573 | * From RFC 2030 (with a correction to the delay math):
|
---|
1574 | *
|
---|
1575 | * Timestamp Name ID When Generated
|
---|
1576 | * ------------------------------------------------------------
|
---|
1577 | * Originate Timestamp T1 time request sent by client
|
---|
1578 | * Receive Timestamp T2 time request received by server
|
---|
1579 | * Transmit Timestamp T3 time reply sent by server
|
---|
1580 | * Destination Timestamp T4 time reply received by client
|
---|
1581 | *
|
---|
1582 | * The roundtrip delay and local clock offset are defined as
|
---|
1583 | *
|
---|
1584 | * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
|
---|
1585 | */
|
---|
1586 | T1 = p->p_xmttime;
|
---|
1587 | T2 = lfp_to_d(msg.m_rectime);
|
---|
1588 | T3 = lfp_to_d(msg.m_xmttime);
|
---|
1589 | T4 = G.cur_time;
|
---|
1590 |
|
---|
1591 | p->lastpkt_recv_time = T4;
|
---|
1592 |
|
---|
1593 | VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
|
---|
1594 | p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
|
---|
1595 | datapoint = &p->filter_datapoint[p->datapoint_idx];
|
---|
1596 | datapoint->d_recv_time = T4;
|
---|
1597 | datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
|
---|
1598 | /* The delay calculation is a special case. In cases where the
|
---|
1599 | * server and client clocks are running at different rates and
|
---|
1600 | * with very fast networks, the delay can appear negative. In
|
---|
1601 | * order to avoid violating the Principle of Least Astonishment,
|
---|
1602 | * the delay is clamped not less than the system precision.
|
---|
1603 | */
|
---|
1604 | p->lastpkt_delay = (T4 - T1) - (T3 - T2);
|
---|
1605 | if (p->lastpkt_delay < G_precision_sec)
|
---|
1606 | p->lastpkt_delay = G_precision_sec;
|
---|
1607 | datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec;
|
---|
1608 | if (!p->reachable_bits) {
|
---|
1609 | /* 1st datapoint ever - replicate offset in every element */
|
---|
1610 | int i;
|
---|
1611 | for (i = 1; i < NUM_DATAPOINTS; i++) {
|
---|
1612 | p->filter_datapoint[i].d_offset = datapoint->d_offset;
|
---|
1613 | }
|
---|
1614 | }
|
---|
1615 |
|
---|
1616 | p->reachable_bits |= 1;
|
---|
1617 | if ((MAX_VERBOSE && G.verbose) || (option_mask32 & OPT_w)) {
|
---|
1618 | bb_error_msg("reply from %s: reach 0x%02x offset %f delay %f status 0x%02x strat %d refid 0x%08x rootdelay %f",
|
---|
1619 | p->p_dotted,
|
---|
1620 | p->reachable_bits,
|
---|
1621 | datapoint->d_offset,
|
---|
1622 | p->lastpkt_delay,
|
---|
1623 | p->lastpkt_status,
|
---|
1624 | p->lastpkt_stratum,
|
---|
1625 | p->lastpkt_refid,
|
---|
1626 | p->lastpkt_rootdelay
|
---|
1627 | /* not shown: m_ppoll, m_precision_exp, m_rootdisp,
|
---|
1628 | * m_reftime, m_orgtime, m_rectime, m_xmttime
|
---|
1629 | */
|
---|
1630 | );
|
---|
1631 | }
|
---|
1632 |
|
---|
1633 | /* Muck with statictics and update the clock */
|
---|
1634 | filter_datapoints(p);
|
---|
1635 | q = select_and_cluster();
|
---|
1636 | rc = -1;
|
---|
1637 | if (q) {
|
---|
1638 | rc = 0;
|
---|
1639 | if (!(option_mask32 & OPT_w)) {
|
---|
1640 | rc = update_local_clock(q);
|
---|
1641 | /* If drift is dangerously large, immediately
|
---|
1642 | * drop poll interval one step down.
|
---|
1643 | */
|
---|
1644 | if (fabs(q->filter_offset) >= POLLDOWN_OFFSET) {
|
---|
1645 | VERB3 bb_error_msg("offset:%f > POLLDOWN_OFFSET", q->filter_offset);
|
---|
1646 | goto poll_down;
|
---|
1647 | }
|
---|
1648 | }
|
---|
1649 | }
|
---|
1650 | /* else: no peer selected, rc = -1: we want to poll more often */
|
---|
1651 |
|
---|
1652 | if (rc != 0) {
|
---|
1653 | /* Adjust the poll interval by comparing the current offset
|
---|
1654 | * with the clock jitter. If the offset is less than
|
---|
1655 | * the clock jitter times a constant, then the averaging interval
|
---|
1656 | * is increased, otherwise it is decreased. A bit of hysteresis
|
---|
1657 | * helps calm the dance. Works best using burst mode.
|
---|
1658 | */
|
---|
1659 | VERB4 if (rc > 0) {
|
---|
1660 | bb_error_msg("offset:%f POLLADJ_GATE*discipline_jitter:%f poll:%s",
|
---|
1661 | q->filter_offset, POLLADJ_GATE * G.discipline_jitter,
|
---|
1662 | fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter
|
---|
1663 | ? "grows" : "falls"
|
---|
1664 | );
|
---|
1665 | }
|
---|
1666 | if (rc > 0 && fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter) {
|
---|
1667 | /* was += G.poll_exp but it is a bit
|
---|
1668 | * too optimistic for my taste at high poll_exp's */
|
---|
1669 | G.polladj_count += MINPOLL;
|
---|
1670 | if (G.polladj_count > POLLADJ_LIMIT) {
|
---|
1671 | G.polladj_count = 0;
|
---|
1672 | if (G.poll_exp < MAXPOLL) {
|
---|
1673 | G.poll_exp++;
|
---|
1674 | VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d",
|
---|
1675 | G.discipline_jitter, G.poll_exp);
|
---|
1676 | }
|
---|
1677 | } else {
|
---|
1678 | VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count);
|
---|
1679 | }
|
---|
1680 | } else {
|
---|
1681 | G.polladj_count -= G.poll_exp * 2;
|
---|
1682 | if (G.polladj_count < -POLLADJ_LIMIT || G.poll_exp >= BIGPOLL) {
|
---|
1683 | poll_down:
|
---|
1684 | G.polladj_count = 0;
|
---|
1685 | if (G.poll_exp > MINPOLL) {
|
---|
1686 | llist_t *item;
|
---|
1687 |
|
---|
1688 | G.poll_exp--;
|
---|
1689 | /* Correct p->next_action_time in each peer
|
---|
1690 | * which waits for sending, so that they send earlier.
|
---|
1691 | * Old pp->next_action_time are on the order
|
---|
1692 | * of t + (1 << old_poll_exp) + small_random,
|
---|
1693 | * we simply need to subtract ~half of that.
|
---|
1694 | */
|
---|
1695 | for (item = G.ntp_peers; item != NULL; item = item->link) {
|
---|
1696 | peer_t *pp = (peer_t *) item->data;
|
---|
1697 | if (pp->p_fd < 0)
|
---|
1698 | pp->next_action_time -= (1 << G.poll_exp);
|
---|
1699 | }
|
---|
1700 | VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d",
|
---|
1701 | G.discipline_jitter, G.poll_exp);
|
---|
1702 | }
|
---|
1703 | } else {
|
---|
1704 | VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count);
|
---|
1705 | }
|
---|
1706 | }
|
---|
1707 | }
|
---|
1708 |
|
---|
1709 | /* Decide when to send new query for this peer */
|
---|
1710 | interval = poll_interval(0);
|
---|
1711 |
|
---|
1712 | set_next_and_close_sock:
|
---|
1713 | set_next(p, interval);
|
---|
1714 | /* We do not expect any more packets from this peer for now.
|
---|
1715 | * Closing the socket informs kernel about it.
|
---|
1716 | * We open a new socket when we send a new query.
|
---|
1717 | */
|
---|
1718 | close(p->p_fd);
|
---|
1719 | p->p_fd = -1;
|
---|
1720 | bail:
|
---|
1721 | return;
|
---|
1722 | }
|
---|
1723 |
|
---|
1724 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
1725 | static NOINLINE void
|
---|
1726 | recv_and_process_client_pkt(void /*int fd*/)
|
---|
1727 | {
|
---|
1728 | ssize_t size;
|
---|
1729 | uint8_t version;
|
---|
1730 | len_and_sockaddr *to;
|
---|
1731 | struct sockaddr *from;
|
---|
1732 | msg_t msg;
|
---|
1733 | uint8_t query_status;
|
---|
1734 | l_fixedpt_t query_xmttime;
|
---|
1735 |
|
---|
1736 | to = get_sock_lsa(G.listen_fd);
|
---|
1737 | from = xzalloc(to->len);
|
---|
1738 |
|
---|
1739 | size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
|
---|
1740 | if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
|
---|
1741 | char *addr;
|
---|
1742 | if (size < 0) {
|
---|
1743 | if (errno == EAGAIN)
|
---|
1744 | goto bail;
|
---|
1745 | bb_perror_msg_and_die("recv");
|
---|
1746 | }
|
---|
1747 | addr = xmalloc_sockaddr2dotted_noport(from);
|
---|
1748 | bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
|
---|
1749 | free(addr);
|
---|
1750 | goto bail;
|
---|
1751 | }
|
---|
1752 |
|
---|
1753 | query_status = msg.m_status;
|
---|
1754 | query_xmttime = msg.m_xmttime;
|
---|
1755 |
|
---|
1756 | /* Build a reply packet */
|
---|
1757 | memset(&msg, 0, sizeof(msg));
|
---|
1758 | msg.m_status = G.stratum < MAXSTRAT ? G.ntp_status : LI_ALARM;
|
---|
1759 | msg.m_status |= (query_status & VERSION_MASK);
|
---|
1760 | msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
|
---|
1761 | MODE_SERVER : MODE_SYM_PAS;
|
---|
1762 | msg.m_stratum = G.stratum;
|
---|
1763 | msg.m_ppoll = G.poll_exp;
|
---|
1764 | msg.m_precision_exp = G_precision_exp;
|
---|
1765 | /* this time was obtained between poll() and recv() */
|
---|
1766 | msg.m_rectime = d_to_lfp(G.cur_time);
|
---|
1767 | msg.m_xmttime = d_to_lfp(gettime1900d()); /* this instant */
|
---|
1768 | if (G.peer_cnt == 0) {
|
---|
1769 | /* we have no peers: "stratum 1 server" mode. reftime = our own time */
|
---|
1770 | G.reftime = G.cur_time;
|
---|
1771 | }
|
---|
1772 | msg.m_reftime = d_to_lfp(G.reftime);
|
---|
1773 | msg.m_orgtime = query_xmttime;
|
---|
1774 | msg.m_rootdelay = d_to_sfp(G.rootdelay);
|
---|
1775 | //simple code does not do this, fix simple code!
|
---|
1776 | msg.m_rootdisp = d_to_sfp(G.rootdisp);
|
---|
1777 | version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
|
---|
1778 | msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3;
|
---|
1779 |
|
---|
1780 | /* We reply from the local address packet was sent to,
|
---|
1781 | * this makes to/from look swapped here: */
|
---|
1782 | do_sendto(G.listen_fd,
|
---|
1783 | /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
|
---|
1784 | &msg, size);
|
---|
1785 |
|
---|
1786 | bail:
|
---|
1787 | free(to);
|
---|
1788 | free(from);
|
---|
1789 | }
|
---|
1790 | #endif
|
---|
1791 |
|
---|
1792 | /* Upstream ntpd's options:
|
---|
1793 | *
|
---|
1794 | * -4 Force DNS resolution of host names to the IPv4 namespace.
|
---|
1795 | * -6 Force DNS resolution of host names to the IPv6 namespace.
|
---|
1796 | * -a Require cryptographic authentication for broadcast client,
|
---|
1797 | * multicast client and symmetric passive associations.
|
---|
1798 | * This is the default.
|
---|
1799 | * -A Do not require cryptographic authentication for broadcast client,
|
---|
1800 | * multicast client and symmetric passive associations.
|
---|
1801 | * This is almost never a good idea.
|
---|
1802 | * -b Enable the client to synchronize to broadcast servers.
|
---|
1803 | * -c conffile
|
---|
1804 | * Specify the name and path of the configuration file,
|
---|
1805 | * default /etc/ntp.conf
|
---|
1806 | * -d Specify debugging mode. This option may occur more than once,
|
---|
1807 | * with each occurrence indicating greater detail of display.
|
---|
1808 | * -D level
|
---|
1809 | * Specify debugging level directly.
|
---|
1810 | * -f driftfile
|
---|
1811 | * Specify the name and path of the frequency file.
|
---|
1812 | * This is the same operation as the "driftfile FILE"
|
---|
1813 | * configuration command.
|
---|
1814 | * -g Normally, ntpd exits with a message to the system log
|
---|
1815 | * if the offset exceeds the panic threshold, which is 1000 s
|
---|
1816 | * by default. This option allows the time to be set to any value
|
---|
1817 | * without restriction; however, this can happen only once.
|
---|
1818 | * If the threshold is exceeded after that, ntpd will exit
|
---|
1819 | * with a message to the system log. This option can be used
|
---|
1820 | * with the -q and -x options. See the tinker command for other options.
|
---|
1821 | * -i jaildir
|
---|
1822 | * Chroot the server to the directory jaildir. This option also implies
|
---|
1823 | * that the server attempts to drop root privileges at startup
|
---|
1824 | * (otherwise, chroot gives very little additional security).
|
---|
1825 | * You may need to also specify a -u option.
|
---|
1826 | * -k keyfile
|
---|
1827 | * Specify the name and path of the symmetric key file,
|
---|
1828 | * default /etc/ntp/keys. This is the same operation
|
---|
1829 | * as the "keys FILE" configuration command.
|
---|
1830 | * -l logfile
|
---|
1831 | * Specify the name and path of the log file. The default
|
---|
1832 | * is the system log file. This is the same operation as
|
---|
1833 | * the "logfile FILE" configuration command.
|
---|
1834 | * -L Do not listen to virtual IPs. The default is to listen.
|
---|
1835 | * -n Don't fork.
|
---|
1836 | * -N To the extent permitted by the operating system,
|
---|
1837 | * run the ntpd at the highest priority.
|
---|
1838 | * -p pidfile
|
---|
1839 | * Specify the name and path of the file used to record the ntpd
|
---|
1840 | * process ID. This is the same operation as the "pidfile FILE"
|
---|
1841 | * configuration command.
|
---|
1842 | * -P priority
|
---|
1843 | * To the extent permitted by the operating system,
|
---|
1844 | * run the ntpd at the specified priority.
|
---|
1845 | * -q Exit the ntpd just after the first time the clock is set.
|
---|
1846 | * This behavior mimics that of the ntpdate program, which is
|
---|
1847 | * to be retired. The -g and -x options can be used with this option.
|
---|
1848 | * Note: The kernel time discipline is disabled with this option.
|
---|
1849 | * -r broadcastdelay
|
---|
1850 | * Specify the default propagation delay from the broadcast/multicast
|
---|
1851 | * server to this client. This is necessary only if the delay
|
---|
1852 | * cannot be computed automatically by the protocol.
|
---|
1853 | * -s statsdir
|
---|
1854 | * Specify the directory path for files created by the statistics
|
---|
1855 | * facility. This is the same operation as the "statsdir DIR"
|
---|
1856 | * configuration command.
|
---|
1857 | * -t key
|
---|
1858 | * Add a key number to the trusted key list. This option can occur
|
---|
1859 | * more than once.
|
---|
1860 | * -u user[:group]
|
---|
1861 | * Specify a user, and optionally a group, to switch to.
|
---|
1862 | * -v variable
|
---|
1863 | * -V variable
|
---|
1864 | * Add a system variable listed by default.
|
---|
1865 | * -x Normally, the time is slewed if the offset is less than the step
|
---|
1866 | * threshold, which is 128 ms by default, and stepped if above
|
---|
1867 | * the threshold. This option sets the threshold to 600 s, which is
|
---|
1868 | * well within the accuracy window to set the clock manually.
|
---|
1869 | * Note: since the slew rate of typical Unix kernels is limited
|
---|
1870 | * to 0.5 ms/s, each second of adjustment requires an amortization
|
---|
1871 | * interval of 2000 s. Thus, an adjustment as much as 600 s
|
---|
1872 | * will take almost 14 days to complete. This option can be used
|
---|
1873 | * with the -g and -q options. See the tinker command for other options.
|
---|
1874 | * Note: The kernel time discipline is disabled with this option.
|
---|
1875 | */
|
---|
1876 |
|
---|
1877 | /* By doing init in a separate function we decrease stack usage
|
---|
1878 | * in main loop.
|
---|
1879 | */
|
---|
1880 | static NOINLINE void ntp_init(char **argv)
|
---|
1881 | {
|
---|
1882 | unsigned opts;
|
---|
1883 | llist_t *peers;
|
---|
1884 |
|
---|
1885 | srandom(getpid());
|
---|
1886 |
|
---|
1887 | if (getuid())
|
---|
1888 | bb_error_msg_and_die(bb_msg_you_must_be_root);
|
---|
1889 |
|
---|
1890 | /* Set some globals */
|
---|
1891 | G.stratum = MAXSTRAT;
|
---|
1892 | if (BURSTPOLL != 0)
|
---|
1893 | G.poll_exp = BURSTPOLL; /* speeds up initial sync */
|
---|
1894 | G.last_script_run = G.reftime = G.last_update_recv_time = gettime1900d(); /* sets G.cur_time too */
|
---|
1895 |
|
---|
1896 | /* Parse options */
|
---|
1897 | peers = NULL;
|
---|
1898 | opt_complementary = "dd:p::wn"; /* d: counter; p: list; -w implies -n */
|
---|
1899 | opts = getopt32(argv,
|
---|
1900 | "nqNx" /* compat */
|
---|
1901 | "wp:S:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
|
---|
1902 | "d" /* compat */
|
---|
1903 | "46aAbgL", /* compat, ignored */
|
---|
1904 | &peers, &G.script_name, &G.verbose);
|
---|
1905 | if (!(opts & (OPT_p|OPT_l)))
|
---|
1906 | bb_show_usage();
|
---|
1907 | // if (opts & OPT_x) /* disable stepping, only slew is allowed */
|
---|
1908 | // G.time_was_stepped = 1;
|
---|
1909 | if (peers) {
|
---|
1910 | while (peers)
|
---|
1911 | add_peers(llist_pop(&peers));
|
---|
1912 | } else {
|
---|
1913 | /* -l but no peers: "stratum 1 server" mode */
|
---|
1914 | G.stratum = 1;
|
---|
1915 | }
|
---|
1916 | if (!(opts & OPT_n)) {
|
---|
1917 | bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
|
---|
1918 | logmode = LOGMODE_NONE;
|
---|
1919 | }
|
---|
1920 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
1921 | G.listen_fd = -1;
|
---|
1922 | if (opts & OPT_l) {
|
---|
1923 | G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
|
---|
1924 | socket_want_pktinfo(G.listen_fd);
|
---|
1925 | setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
|
---|
1926 | }
|
---|
1927 | #endif
|
---|
1928 | /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
|
---|
1929 | if (opts & OPT_N)
|
---|
1930 | setpriority(PRIO_PROCESS, 0, -15);
|
---|
1931 |
|
---|
1932 | /* If network is up, syncronization occurs in ~10 seconds.
|
---|
1933 | * We give "ntpd -q" a full minute to finish, then we exit.
|
---|
1934 | *
|
---|
1935 | * I tested ntpd 4.2.6p1 and apparently it never exits
|
---|
1936 | * (will try forever), but it does not feel right.
|
---|
1937 | * The goal of -q is to act like ntpdate: set time
|
---|
1938 | * after a reasonably small period of polling, or fail.
|
---|
1939 | */
|
---|
1940 | if (opts & OPT_q)
|
---|
1941 | alarm(60);
|
---|
1942 |
|
---|
1943 | bb_signals(0
|
---|
1944 | | (1 << SIGTERM)
|
---|
1945 | | (1 << SIGINT)
|
---|
1946 | | (1 << SIGALRM)
|
---|
1947 | , record_signo
|
---|
1948 | );
|
---|
1949 | bb_signals(0
|
---|
1950 | | (1 << SIGPIPE)
|
---|
1951 | | (1 << SIGCHLD)
|
---|
1952 | , SIG_IGN
|
---|
1953 | );
|
---|
1954 | }
|
---|
1955 |
|
---|
1956 | int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
1957 | int ntpd_main(int argc UNUSED_PARAM, char **argv)
|
---|
1958 | {
|
---|
1959 | #undef G
|
---|
1960 | struct globals G;
|
---|
1961 | struct pollfd *pfd;
|
---|
1962 | peer_t **idx2peer;
|
---|
1963 | unsigned cnt;
|
---|
1964 |
|
---|
1965 | memset(&G, 0, sizeof(G));
|
---|
1966 | SET_PTR_TO_GLOBALS(&G);
|
---|
1967 |
|
---|
1968 | ntp_init(argv);
|
---|
1969 |
|
---|
1970 | /* If ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
|
---|
1971 | cnt = G.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
|
---|
1972 | idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
|
---|
1973 | pfd = xzalloc(sizeof(pfd[0]) * cnt);
|
---|
1974 |
|
---|
1975 | /* Countdown: we never sync before we sent INITIAL_SAMPLES+1
|
---|
1976 | * packets to each peer.
|
---|
1977 | * NB: if some peer is not responding, we may end up sending
|
---|
1978 | * fewer packets to it and more to other peers.
|
---|
1979 | * NB2: sync usually happens using INITIAL_SAMPLES packets,
|
---|
1980 | * since last reply does not come back instantaneously.
|
---|
1981 | */
|
---|
1982 | cnt = G.peer_cnt * (INITIAL_SAMPLES + 1);
|
---|
1983 |
|
---|
1984 | while (!bb_got_signal) {
|
---|
1985 | llist_t *item;
|
---|
1986 | unsigned i, j;
|
---|
1987 | int nfds, timeout;
|
---|
1988 | double nextaction;
|
---|
1989 |
|
---|
1990 | /* Nothing between here and poll() blocks for any significant time */
|
---|
1991 |
|
---|
1992 | nextaction = G.cur_time + 3600;
|
---|
1993 |
|
---|
1994 | i = 0;
|
---|
1995 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
1996 | if (G.listen_fd != -1) {
|
---|
1997 | pfd[0].fd = G.listen_fd;
|
---|
1998 | pfd[0].events = POLLIN;
|
---|
1999 | i++;
|
---|
2000 | }
|
---|
2001 | #endif
|
---|
2002 | /* Pass over peer list, send requests, time out on receives */
|
---|
2003 | for (item = G.ntp_peers; item != NULL; item = item->link) {
|
---|
2004 | peer_t *p = (peer_t *) item->data;
|
---|
2005 |
|
---|
2006 | if (p->next_action_time <= G.cur_time) {
|
---|
2007 | if (p->p_fd == -1) {
|
---|
2008 | /* Time to send new req */
|
---|
2009 | if (--cnt == 0) {
|
---|
2010 | G.initial_poll_complete = 1;
|
---|
2011 | }
|
---|
2012 | send_query_to_peer(p);
|
---|
2013 | } else {
|
---|
2014 | /* Timed out waiting for reply */
|
---|
2015 | close(p->p_fd);
|
---|
2016 | p->p_fd = -1;
|
---|
2017 | timeout = poll_interval(-2); /* -2: try a bit sooner */
|
---|
2018 | bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us",
|
---|
2019 | p->p_dotted, p->reachable_bits, timeout);
|
---|
2020 | set_next(p, timeout);
|
---|
2021 | }
|
---|
2022 | }
|
---|
2023 |
|
---|
2024 | if (p->next_action_time < nextaction)
|
---|
2025 | nextaction = p->next_action_time;
|
---|
2026 |
|
---|
2027 | if (p->p_fd >= 0) {
|
---|
2028 | /* Wait for reply from this peer */
|
---|
2029 | pfd[i].fd = p->p_fd;
|
---|
2030 | pfd[i].events = POLLIN;
|
---|
2031 | idx2peer[i] = p;
|
---|
2032 | i++;
|
---|
2033 | }
|
---|
2034 | }
|
---|
2035 |
|
---|
2036 | timeout = nextaction - G.cur_time;
|
---|
2037 | if (timeout < 0)
|
---|
2038 | timeout = 0;
|
---|
2039 | timeout++; /* (nextaction - G.cur_time) rounds down, compensating */
|
---|
2040 |
|
---|
2041 | /* Here we may block */
|
---|
2042 | VERB2 bb_error_msg("poll %us, sockets:%u, poll interval:%us", timeout, i, 1 << G.poll_exp);
|
---|
2043 | nfds = poll(pfd, i, timeout * 1000);
|
---|
2044 | gettime1900d(); /* sets G.cur_time */
|
---|
2045 | if (nfds <= 0) {
|
---|
2046 | if (G.script_name && G.cur_time - G.last_script_run > 11*60) {
|
---|
2047 | /* Useful for updating battery-backed RTC and such */
|
---|
2048 | run_script("periodic", G.last_update_offset);
|
---|
2049 | gettime1900d(); /* sets G.cur_time */
|
---|
2050 | }
|
---|
2051 | continue;
|
---|
2052 | }
|
---|
2053 |
|
---|
2054 | /* Process any received packets */
|
---|
2055 | j = 0;
|
---|
2056 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
2057 | if (G.listen_fd != -1) {
|
---|
2058 | if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
|
---|
2059 | nfds--;
|
---|
2060 | recv_and_process_client_pkt(/*G.listen_fd*/);
|
---|
2061 | gettime1900d(); /* sets G.cur_time */
|
---|
2062 | }
|
---|
2063 | j = 1;
|
---|
2064 | }
|
---|
2065 | #endif
|
---|
2066 | for (; nfds != 0 && j < i; j++) {
|
---|
2067 | if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
|
---|
2068 | nfds--;
|
---|
2069 | recv_and_process_peer_pkt(idx2peer[j]);
|
---|
2070 | gettime1900d(); /* sets G.cur_time */
|
---|
2071 | }
|
---|
2072 | }
|
---|
2073 | } /* while (!bb_got_signal) */
|
---|
2074 |
|
---|
2075 | kill_myself_with_sig(bb_got_signal);
|
---|
2076 | }
|
---|
2077 |
|
---|
2078 |
|
---|
2079 |
|
---|
2080 |
|
---|
2081 |
|
---|
2082 |
|
---|
2083 | /*** openntpd-4.6 uses only adjtime, not adjtimex ***/
|
---|
2084 |
|
---|
2085 | /*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/
|
---|
2086 |
|
---|
2087 | #if 0
|
---|
2088 | static double
|
---|
2089 | direct_freq(double fp_offset)
|
---|
2090 | {
|
---|
2091 | #ifdef KERNEL_PLL
|
---|
2092 | /*
|
---|
2093 | * If the kernel is enabled, we need the residual offset to
|
---|
2094 | * calculate the frequency correction.
|
---|
2095 | */
|
---|
2096 | if (pll_control && kern_enable) {
|
---|
2097 | memset(&ntv, 0, sizeof(ntv));
|
---|
2098 | ntp_adjtime(&ntv);
|
---|
2099 | #ifdef STA_NANO
|
---|
2100 | clock_offset = ntv.offset / 1e9;
|
---|
2101 | #else /* STA_NANO */
|
---|
2102 | clock_offset = ntv.offset / 1e6;
|
---|
2103 | #endif /* STA_NANO */
|
---|
2104 | drift_comp = FREQTOD(ntv.freq);
|
---|
2105 | }
|
---|
2106 | #endif /* KERNEL_PLL */
|
---|
2107 | set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp);
|
---|
2108 | wander_resid = 0;
|
---|
2109 | return drift_comp;
|
---|
2110 | }
|
---|
2111 |
|
---|
2112 | static void
|
---|
2113 | set_freq(double freq) /* frequency update */
|
---|
2114 | {
|
---|
2115 | char tbuf[80];
|
---|
2116 |
|
---|
2117 | drift_comp = freq;
|
---|
2118 |
|
---|
2119 | #ifdef KERNEL_PLL
|
---|
2120 | /*
|
---|
2121 | * If the kernel is enabled, update the kernel frequency.
|
---|
2122 | */
|
---|
2123 | if (pll_control && kern_enable) {
|
---|
2124 | memset(&ntv, 0, sizeof(ntv));
|
---|
2125 | ntv.modes = MOD_FREQUENCY;
|
---|
2126 | ntv.freq = DTOFREQ(drift_comp);
|
---|
2127 | ntp_adjtime(&ntv);
|
---|
2128 | snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6);
|
---|
2129 | report_event(EVNT_FSET, NULL, tbuf);
|
---|
2130 | } else {
|
---|
2131 | snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
|
---|
2132 | report_event(EVNT_FSET, NULL, tbuf);
|
---|
2133 | }
|
---|
2134 | #else /* KERNEL_PLL */
|
---|
2135 | snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6);
|
---|
2136 | report_event(EVNT_FSET, NULL, tbuf);
|
---|
2137 | #endif /* KERNEL_PLL */
|
---|
2138 | }
|
---|
2139 |
|
---|
2140 | ...
|
---|
2141 | ...
|
---|
2142 | ...
|
---|
2143 |
|
---|
2144 | #ifdef KERNEL_PLL
|
---|
2145 | /*
|
---|
2146 | * This code segment works when clock adjustments are made using
|
---|
2147 | * precision time kernel support and the ntp_adjtime() system
|
---|
2148 | * call. This support is available in Solaris 2.6 and later,
|
---|
2149 | * Digital Unix 4.0 and later, FreeBSD, Linux and specially
|
---|
2150 | * modified kernels for HP-UX 9 and Ultrix 4. In the case of the
|
---|
2151 | * DECstation 5000/240 and Alpha AXP, additional kernel
|
---|
2152 | * modifications provide a true microsecond clock and nanosecond
|
---|
2153 | * clock, respectively.
|
---|
2154 | *
|
---|
2155 | * Important note: The kernel discipline is used only if the
|
---|
2156 | * step threshold is less than 0.5 s, as anything higher can
|
---|
2157 | * lead to overflow problems. This might occur if some misguided
|
---|
2158 | * lad set the step threshold to something ridiculous.
|
---|
2159 | */
|
---|
2160 | if (pll_control && kern_enable) {
|
---|
2161 |
|
---|
2162 | #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST)
|
---|
2163 |
|
---|
2164 | /*
|
---|
2165 | * We initialize the structure for the ntp_adjtime()
|
---|
2166 | * system call. We have to convert everything to
|
---|
2167 | * microseconds or nanoseconds first. Do not update the
|
---|
2168 | * system variables if the ext_enable flag is set. In
|
---|
2169 | * this case, the external clock driver will update the
|
---|
2170 | * variables, which will be read later by the local
|
---|
2171 | * clock driver. Afterwards, remember the time and
|
---|
2172 | * frequency offsets for jitter and stability values and
|
---|
2173 | * to update the frequency file.
|
---|
2174 | */
|
---|
2175 | memset(&ntv, 0, sizeof(ntv));
|
---|
2176 | if (ext_enable) {
|
---|
2177 | ntv.modes = MOD_STATUS;
|
---|
2178 | } else {
|
---|
2179 | #ifdef STA_NANO
|
---|
2180 | ntv.modes = MOD_BITS | MOD_NANO;
|
---|
2181 | #else /* STA_NANO */
|
---|
2182 | ntv.modes = MOD_BITS;
|
---|
2183 | #endif /* STA_NANO */
|
---|
2184 | if (clock_offset < 0)
|
---|
2185 | dtemp = -.5;
|
---|
2186 | else
|
---|
2187 | dtemp = .5;
|
---|
2188 | #ifdef STA_NANO
|
---|
2189 | ntv.offset = (int32)(clock_offset * 1e9 + dtemp);
|
---|
2190 | ntv.constant = sys_poll;
|
---|
2191 | #else /* STA_NANO */
|
---|
2192 | ntv.offset = (int32)(clock_offset * 1e6 + dtemp);
|
---|
2193 | ntv.constant = sys_poll - 4;
|
---|
2194 | #endif /* STA_NANO */
|
---|
2195 | ntv.esterror = (u_int32)(clock_jitter * 1e6);
|
---|
2196 | ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
|
---|
2197 | ntv.status = STA_PLL;
|
---|
2198 |
|
---|
2199 | /*
|
---|
2200 | * Enable/disable the PPS if requested.
|
---|
2201 | */
|
---|
2202 | if (pps_enable) {
|
---|
2203 | if (!(pll_status & STA_PPSTIME))
|
---|
2204 | report_event(EVNT_KERN,
|
---|
2205 | NULL, "PPS enabled");
|
---|
2206 | ntv.status |= STA_PPSTIME | STA_PPSFREQ;
|
---|
2207 | } else {
|
---|
2208 | if (pll_status & STA_PPSTIME)
|
---|
2209 | report_event(EVNT_KERN,
|
---|
2210 | NULL, "PPS disabled");
|
---|
2211 | ntv.status &= ~(STA_PPSTIME |
|
---|
2212 | STA_PPSFREQ);
|
---|
2213 | }
|
---|
2214 | if (sys_leap == LEAP_ADDSECOND)
|
---|
2215 | ntv.status |= STA_INS;
|
---|
2216 | else if (sys_leap == LEAP_DELSECOND)
|
---|
2217 | ntv.status |= STA_DEL;
|
---|
2218 | }
|
---|
2219 |
|
---|
2220 | /*
|
---|
2221 | * Pass the stuff to the kernel. If it squeals, turn off
|
---|
2222 | * the pps. In any case, fetch the kernel offset,
|
---|
2223 | * frequency and jitter.
|
---|
2224 | */
|
---|
2225 | if (ntp_adjtime(&ntv) == TIME_ERROR) {
|
---|
2226 | if (!(ntv.status & STA_PPSSIGNAL))
|
---|
2227 | report_event(EVNT_KERN, NULL,
|
---|
2228 | "PPS no signal");
|
---|
2229 | }
|
---|
2230 | pll_status = ntv.status;
|
---|
2231 | #ifdef STA_NANO
|
---|
2232 | clock_offset = ntv.offset / 1e9;
|
---|
2233 | #else /* STA_NANO */
|
---|
2234 | clock_offset = ntv.offset / 1e6;
|
---|
2235 | #endif /* STA_NANO */
|
---|
2236 | clock_frequency = FREQTOD(ntv.freq);
|
---|
2237 |
|
---|
2238 | /*
|
---|
2239 | * If the kernel PPS is lit, monitor its performance.
|
---|
2240 | */
|
---|
2241 | if (ntv.status & STA_PPSTIME) {
|
---|
2242 | #ifdef STA_NANO
|
---|
2243 | clock_jitter = ntv.jitter / 1e9;
|
---|
2244 | #else /* STA_NANO */
|
---|
2245 | clock_jitter = ntv.jitter / 1e6;
|
---|
2246 | #endif /* STA_NANO */
|
---|
2247 | }
|
---|
2248 |
|
---|
2249 | #if defined(STA_NANO) && NTP_API == 4
|
---|
2250 | /*
|
---|
2251 | * If the TAI changes, update the kernel TAI.
|
---|
2252 | */
|
---|
2253 | if (loop_tai != sys_tai) {
|
---|
2254 | loop_tai = sys_tai;
|
---|
2255 | ntv.modes = MOD_TAI;
|
---|
2256 | ntv.constant = sys_tai;
|
---|
2257 | ntp_adjtime(&ntv);
|
---|
2258 | }
|
---|
2259 | #endif /* STA_NANO */
|
---|
2260 | }
|
---|
2261 | #endif /* KERNEL_PLL */
|
---|
2262 | #endif
|
---|