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 | #include "libbb.h"
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9 | #include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
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10 | #ifndef IPTOS_LOWDELAY
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11 | # define IPTOS_LOWDELAY 0x10
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12 | #endif
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13 | #ifndef IP_PKTINFO
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14 | # error "Sorry, your kernel has to support IP_PKTINFO"
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15 | #endif
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16 |
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17 |
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18 | /* Sync to peers every N secs */
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19 | #define INTERVAL_QUERY_NORMAL 30
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20 | #define INTERVAL_QUERY_PATHETIC 60
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21 | #define INTERVAL_QUERY_AGRESSIVE 5
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22 |
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23 | /* Bad if *less than* TRUSTLEVEL_BADPEER */
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24 | #define TRUSTLEVEL_BADPEER 6
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25 | #define TRUSTLEVEL_PATHETIC 2
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26 | #define TRUSTLEVEL_AGRESSIVE 8
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27 | #define TRUSTLEVEL_MAX 10
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28 |
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29 | #define QSCALE_OFF_MIN 0.05
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30 | #define QSCALE_OFF_MAX 0.50
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31 |
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32 | /* Single query might take N secs max */
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33 | #define QUERYTIME_MAX 15
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34 | /* Min offset for settime at start. "man ntpd" says it's 128 ms */
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35 | #define STEPTIME_MIN_OFFSET 0.128
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36 |
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37 | typedef struct {
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38 | uint32_t int_partl;
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39 | uint32_t fractionl;
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40 | } l_fixedpt_t;
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41 |
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42 | typedef struct {
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43 | uint16_t int_parts;
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44 | uint16_t fractions;
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45 | } s_fixedpt_t;
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46 |
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47 | enum {
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48 | NTP_DIGESTSIZE = 16,
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49 | NTP_MSGSIZE_NOAUTH = 48,
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50 | NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
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51 | };
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52 |
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53 | typedef struct {
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54 | uint8_t m_status; /* status of local clock and leap info */
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55 | uint8_t m_stratum; /* stratum level */
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56 | uint8_t m_ppoll; /* poll value */
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57 | int8_t m_precision_exp;
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58 | s_fixedpt_t m_rootdelay;
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59 | s_fixedpt_t m_dispersion;
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60 | uint32_t m_refid;
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61 | l_fixedpt_t m_reftime;
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62 | l_fixedpt_t m_orgtime;
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63 | l_fixedpt_t m_rectime;
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64 | l_fixedpt_t m_xmttime;
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65 | uint32_t m_keyid;
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66 | uint8_t m_digest[NTP_DIGESTSIZE];
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67 | } msg_t;
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68 |
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69 | enum {
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70 | NTP_VERSION = 4,
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71 | NTP_MAXSTRATUM = 15,
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72 |
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73 | /* Status Masks */
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74 | MODE_MASK = (7 << 0),
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75 | VERSION_MASK = (7 << 3),
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76 | VERSION_SHIFT = 3,
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77 | LI_MASK = (3 << 6),
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78 |
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79 | /* Leap Second Codes (high order two bits of m_status) */
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80 | LI_NOWARNING = (0 << 6), /* no warning */
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81 | LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */
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82 | LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */
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83 | LI_ALARM = (3 << 6), /* alarm condition */
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84 |
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85 | /* Mode values */
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86 | MODE_RES0 = 0, /* reserved */
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87 | MODE_SYM_ACT = 1, /* symmetric active */
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88 | MODE_SYM_PAS = 2, /* symmetric passive */
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89 | MODE_CLIENT = 3, /* client */
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90 | MODE_SERVER = 4, /* server */
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91 | MODE_BROADCAST = 5, /* broadcast */
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92 | MODE_RES1 = 6, /* reserved for NTP control message */
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93 | MODE_RES2 = 7, /* reserved for private use */
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94 | };
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95 |
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96 | #define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */
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97 |
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98 | typedef struct {
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99 | double d_offset;
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100 | double d_delay;
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101 | //UNUSED: double d_error;
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102 | time_t d_rcv_time;
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103 | uint32_t d_refid4;
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104 | uint8_t d_leap;
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105 | uint8_t d_stratum;
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106 | uint8_t d_good;
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107 | } datapoint_t;
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108 |
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109 | #define NUM_DATAPOINTS 8
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110 | typedef struct {
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111 | len_and_sockaddr *p_lsa;
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112 | char *p_dotted;
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113 | /* When to send new query (if p_fd == -1)
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114 | * or when receive times out (if p_fd >= 0): */
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115 | time_t next_action_time;
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116 | int p_fd;
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117 | uint8_t p_datapoint_idx;
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118 | uint8_t p_trustlevel;
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119 | double p_xmttime;
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120 | datapoint_t update;
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121 | datapoint_t p_datapoint[NUM_DATAPOINTS];
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122 | msg_t p_xmt_msg;
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123 | } peer_t;
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124 |
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125 | enum {
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126 | OPT_n = (1 << 0),
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127 | OPT_q = (1 << 1),
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128 | OPT_N = (1 << 2),
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129 | OPT_x = (1 << 3),
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130 | /* Insert new options above this line. */
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131 | /* Non-compat options: */
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132 | OPT_p = (1 << 4),
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133 | OPT_l = (1 << 5) * ENABLE_FEATURE_NTPD_SERVER,
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134 | };
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135 |
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136 |
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137 | struct globals {
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138 | /* total round trip delay to currently selected reference clock */
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139 | double rootdelay;
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140 | /* reference timestamp: time when the system clock was last set or corrected */
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141 | double reftime;
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142 | llist_t *ntp_peers;
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143 | #if ENABLE_FEATURE_NTPD_SERVER
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144 | int listen_fd;
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145 | #endif
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146 | unsigned verbose;
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147 | unsigned peer_cnt;
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148 | unsigned scale;
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149 | uint32_t refid;
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150 | uint32_t refid4;
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151 | uint8_t synced;
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152 | uint8_t leap;
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153 | #define G_precision_exp -6
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154 | // int8_t precision_exp;
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155 | uint8_t stratum;
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156 | uint8_t time_was_stepped;
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157 | uint8_t first_adj_done;
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158 | };
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159 | #define G (*ptr_to_globals)
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160 |
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161 | static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
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162 |
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163 |
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164 | static void
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165 | set_next(peer_t *p, unsigned t)
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166 | {
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167 | p->next_action_time = time(NULL) + t;
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168 | }
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169 |
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170 | static void
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171 | add_peers(char *s)
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172 | {
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173 | peer_t *p;
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174 |
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175 | p = xzalloc(sizeof(*p));
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176 | p->p_lsa = xhost2sockaddr(s, 123);
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177 | p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
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178 | p->p_fd = -1;
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179 | p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
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180 | p->p_trustlevel = TRUSTLEVEL_PATHETIC;
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181 | p->next_action_time = time(NULL); /* = set_next(p, 0); */
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182 |
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183 | llist_add_to(&G.ntp_peers, p);
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184 | G.peer_cnt++;
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185 | }
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186 |
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187 | static double
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188 | gettime1900d(void)
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189 | {
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190 | struct timeval tv;
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191 | gettimeofday(&tv, NULL); /* never fails */
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192 | return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970);
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193 | }
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194 |
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195 | static void
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196 | d_to_tv(double d, struct timeval *tv)
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197 | {
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198 | tv->tv_sec = (long)d;
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199 | tv->tv_usec = (d - tv->tv_sec) * 1000000;
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200 | }
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201 |
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202 | static double
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203 | lfp_to_d(l_fixedpt_t lfp)
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204 | {
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205 | double ret;
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206 | lfp.int_partl = ntohl(lfp.int_partl);
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207 | lfp.fractionl = ntohl(lfp.fractionl);
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208 | ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
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209 | return ret;
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210 | }
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211 |
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212 | #if 0 //UNUSED
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213 | static double
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214 | sfp_to_d(s_fixedpt_t sfp)
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215 | {
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216 | double ret;
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217 | sfp.int_parts = ntohs(sfp.int_parts);
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218 | sfp.fractions = ntohs(sfp.fractions);
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219 | ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
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220 | return ret;
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221 | }
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222 | #endif
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223 |
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224 | #if ENABLE_FEATURE_NTPD_SERVER
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225 | static l_fixedpt_t
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226 | d_to_lfp(double d)
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227 | {
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228 | l_fixedpt_t lfp;
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229 | lfp.int_partl = (uint32_t)d;
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230 | lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
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231 | lfp.int_partl = htonl(lfp.int_partl);
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232 | lfp.fractionl = htonl(lfp.fractionl);
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233 | return lfp;
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234 | }
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235 |
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236 | static s_fixedpt_t
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237 | d_to_sfp(double d)
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238 | {
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239 | s_fixedpt_t sfp;
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240 | sfp.int_parts = (uint16_t)d;
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241 | sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
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242 | sfp.int_parts = htons(sfp.int_parts);
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243 | sfp.fractions = htons(sfp.fractions);
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244 | return sfp;
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245 | }
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246 | #endif
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247 |
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248 | static unsigned
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249 | error_interval(void)
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250 | {
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251 | unsigned interval, r;
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252 | interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN;
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253 | r = (unsigned)random() % (unsigned)(interval / 10);
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254 | return (interval + r);
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255 | }
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256 |
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257 | static int
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258 | do_sendto(int fd,
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259 | const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
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260 | msg_t *msg, ssize_t len)
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261 | {
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262 | ssize_t ret;
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263 |
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264 | errno = 0;
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265 | if (!from) {
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266 | ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
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267 | } else {
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268 | ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
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269 | }
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270 | if (ret != len) {
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271 | bb_perror_msg("send failed");
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272 | return -1;
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273 | }
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274 | return 0;
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275 | }
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276 |
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277 | static int
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278 | send_query_to_peer(peer_t *p)
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279 | {
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280 | // Why do we need to bind()?
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281 | // See what happens when we don't bind:
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282 | //
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283 | // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
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284 | // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
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285 | // gettimeofday({1259071266, 327885}, NULL) = 0
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286 | // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
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287 | // ^^^ we sent it from some source port picked by kernel.
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288 | // time(NULL) = 1259071266
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289 | // write(2, "ntpd: entering poll 15 secs\n", 28) = 28
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290 | // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
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291 | // recv(3, "yyy", 68, MSG_DONTWAIT) = 48
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292 | // ^^^ this recv will receive packets to any local port!
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293 | //
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294 | // Uncomment this and use strace to see it in action:
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295 | #define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); }
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296 |
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297 | if (p->p_fd == -1) {
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298 | int fd, family;
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299 | len_and_sockaddr *local_lsa;
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300 |
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301 | family = p->p_lsa->u.sa.sa_family;
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302 | p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
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303 | /* local_lsa has "null" address and port 0 now.
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304 | * bind() ensures we have a *particular port* selected by kernel
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305 | * and remembered in p->p_fd, thus later recv(p->p_fd)
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306 | * receives only packets sent to this port.
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307 | */
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308 | PROBE_LOCAL_ADDR
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309 | xbind(fd, &local_lsa->u.sa, local_lsa->len);
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310 | PROBE_LOCAL_ADDR
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311 | #if ENABLE_FEATURE_IPV6
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312 | if (family == AF_INET)
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313 | #endif
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314 | setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
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315 | free(local_lsa);
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316 | }
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317 |
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318 | /*
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319 | * Send out a random 64-bit number as our transmit time. The NTP
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320 | * server will copy said number into the originate field on the
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321 | * response that it sends us. This is totally legal per the SNTP spec.
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322 | *
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323 | * The impact of this is two fold: we no longer send out the current
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324 | * system time for the world to see (which may aid an attacker), and
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325 | * it gives us a (not very secure) way of knowing that we're not
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326 | * getting spoofed by an attacker that can't capture our traffic
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327 | * but can spoof packets from the NTP server we're communicating with.
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328 | *
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329 | * Save the real transmit timestamp locally.
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330 | */
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331 | p->p_xmt_msg.m_xmttime.int_partl = random();
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332 | p->p_xmt_msg.m_xmttime.fractionl = random();
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333 | p->p_xmttime = gettime1900d();
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334 |
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335 | if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
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336 | &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
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337 | ) {
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338 | close(p->p_fd);
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339 | p->p_fd = -1;
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340 | set_next(p, INTERVAL_QUERY_PATHETIC);
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341 | return -1;
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342 | }
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343 |
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344 | if (G.verbose)
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345 | bb_error_msg("sent query to %s", p->p_dotted);
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346 | set_next(p, QUERYTIME_MAX);
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347 |
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348 | return 0;
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349 | }
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350 |
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351 |
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352 | /* Time is stepped only once, when the first packet from a peer is received.
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353 | */
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354 | static void
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355 | step_time_once(double offset)
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356 | {
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357 | double dtime;
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358 | llist_t *item;
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359 | struct timeval tv;
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360 | char buf[80];
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361 | time_t tval;
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362 |
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363 | if (G.time_was_stepped)
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364 | goto bail;
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365 | G.time_was_stepped = 1;
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366 |
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367 | /* if the offset is small, don't step, slew (later) */
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368 | if (offset < STEPTIME_MIN_OFFSET && offset > -STEPTIME_MIN_OFFSET)
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369 | goto bail;
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370 |
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371 | gettimeofday(&tv, NULL); /* never fails */
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372 | dtime = offset + tv.tv_sec;
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373 | dtime += 1.0e-6 * tv.tv_usec;
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374 | d_to_tv(dtime, &tv);
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375 |
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376 | if (settimeofday(&tv, NULL) == -1)
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377 | bb_perror_msg_and_die("settimeofday");
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378 |
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379 | tval = tv.tv_sec;
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380 | strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
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381 |
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382 | bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
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383 |
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384 | for (item = G.ntp_peers; item != NULL; item = item->link) {
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385 | peer_t *p = (peer_t *) item->data;
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386 | p->next_action_time -= (time_t)offset;
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387 | }
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388 |
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389 | bail:
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390 | if (option_mask32 & OPT_q)
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391 | exit(0);
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392 | }
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393 |
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394 |
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395 | /* Time is periodically slewed when we collect enough
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396 | * good data points.
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397 | */
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398 | static int
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399 | compare_offsets(const void *aa, const void *bb)
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400 | {
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401 | const peer_t *const *a = aa;
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402 | const peer_t *const *b = bb;
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403 | if ((*a)->update.d_offset < (*b)->update.d_offset)
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404 | return -1;
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405 | return ((*a)->update.d_offset > (*b)->update.d_offset);
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406 | }
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407 | static unsigned
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408 | updated_scale(double offset)
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409 | {
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410 | if (offset < 0)
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411 | offset = -offset;
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412 | if (offset > QSCALE_OFF_MAX)
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413 | return 1;
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414 | if (offset < QSCALE_OFF_MIN)
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415 | return QSCALE_OFF_MAX / QSCALE_OFF_MIN;
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416 | return QSCALE_OFF_MAX / offset;
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417 | }
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418 | static void
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419 | slew_time(void)
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420 | {
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421 | llist_t *item;
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422 | double offset_median;
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423 | struct timeval tv;
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424 |
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425 | {
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426 | peer_t **peers = xzalloc(sizeof(peers[0]) * G.peer_cnt);
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427 | unsigned goodpeer_cnt = 0;
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428 | unsigned middle;
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429 |
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430 | for (item = G.ntp_peers; item != NULL; item = item->link) {
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431 | peer_t *p = (peer_t *) item->data;
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432 | if (p->p_trustlevel < TRUSTLEVEL_BADPEER)
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433 | continue;
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434 | if (!p->update.d_good) {
|
---|
435 | free(peers);
|
---|
436 | return;
|
---|
437 | }
|
---|
438 | peers[goodpeer_cnt++] = p;
|
---|
439 | }
|
---|
440 |
|
---|
441 | if (goodpeer_cnt == 0) {
|
---|
442 | free(peers);
|
---|
443 | goto clear_good;
|
---|
444 | }
|
---|
445 |
|
---|
446 | qsort(peers, goodpeer_cnt, sizeof(peers[0]), compare_offsets);
|
---|
447 |
|
---|
448 | middle = goodpeer_cnt / 2;
|
---|
449 | if (middle != 0 && (goodpeer_cnt & 1) == 0) {
|
---|
450 | offset_median = (peers[middle-1]->update.d_offset + peers[middle]->update.d_offset) / 2;
|
---|
451 | G.rootdelay = (peers[middle-1]->update.d_delay + peers[middle]->update.d_delay) / 2;
|
---|
452 | G.stratum = 1 + MAX(peers[middle-1]->update.d_stratum, peers[middle]->update.d_stratum);
|
---|
453 | } else {
|
---|
454 | offset_median = peers[middle]->update.d_offset;
|
---|
455 | G.rootdelay = peers[middle]->update.d_delay;
|
---|
456 | G.stratum = 1 + peers[middle]->update.d_stratum;
|
---|
457 | }
|
---|
458 | G.leap = peers[middle]->update.d_leap;
|
---|
459 | G.refid4 = peers[middle]->update.d_refid4;
|
---|
460 | G.refid =
|
---|
461 | #if ENABLE_FEATURE_IPV6
|
---|
462 | peers[middle]->p_lsa->u.sa.sa_family != AF_INET ?
|
---|
463 | G.refid4 :
|
---|
464 | #endif
|
---|
465 | peers[middle]->p_lsa->u.sin.sin_addr.s_addr;
|
---|
466 | free(peers);
|
---|
467 | }
|
---|
468 | //TODO: if (offset_median > BIG) step_time(offset_median)?
|
---|
469 |
|
---|
470 | G.scale = updated_scale(offset_median);
|
---|
471 |
|
---|
472 | bb_error_msg("adjusting clock by %fs, our stratum is %u, time scale %u",
|
---|
473 | offset_median, G.stratum, G.scale);
|
---|
474 |
|
---|
475 | errno = 0;
|
---|
476 | d_to_tv(offset_median, &tv);
|
---|
477 | if (adjtime(&tv, &tv) == -1)
|
---|
478 | bb_perror_msg_and_die("adjtime failed");
|
---|
479 | if (G.verbose >= 2)
|
---|
480 | bb_error_msg("old adjust: %d.%06u", (int)tv.tv_sec, (unsigned)tv.tv_usec);
|
---|
481 |
|
---|
482 | if (G.first_adj_done) {
|
---|
483 | uint8_t synced = (tv.tv_sec == 0 && tv.tv_usec == 0);
|
---|
484 | if (synced != G.synced) {
|
---|
485 | G.synced = synced;
|
---|
486 | bb_error_msg("clock is %ssynced", synced ? "" : "un");
|
---|
487 | }
|
---|
488 | }
|
---|
489 | G.first_adj_done = 1;
|
---|
490 |
|
---|
491 | G.reftime = gettime1900d();
|
---|
492 |
|
---|
493 | clear_good:
|
---|
494 | for (item = G.ntp_peers; item != NULL; item = item->link) {
|
---|
495 | peer_t *p = (peer_t *) item->data;
|
---|
496 | p->update.d_good = 0;
|
---|
497 | }
|
---|
498 | }
|
---|
499 |
|
---|
500 | static void
|
---|
501 | update_peer_data(peer_t *p)
|
---|
502 | {
|
---|
503 | /* Clock filter.
|
---|
504 | * Find the datapoint with the lowest delay.
|
---|
505 | * Use that as the peer update.
|
---|
506 | * Invalidate it and all older ones.
|
---|
507 | */
|
---|
508 | int i;
|
---|
509 | int best = -1;
|
---|
510 | int good = 0;
|
---|
511 |
|
---|
512 | for (i = 0; i < NUM_DATAPOINTS; i++) {
|
---|
513 | if (p->p_datapoint[i].d_good) {
|
---|
514 | good++;
|
---|
515 | if (best < 0 || p->p_datapoint[i].d_delay < p->p_datapoint[best].d_delay)
|
---|
516 | best = i;
|
---|
517 | }
|
---|
518 | }
|
---|
519 |
|
---|
520 | if (good < 8) //FIXME: was it meant to be NUM_DATAPOINTS, not 8?
|
---|
521 | return;
|
---|
522 |
|
---|
523 | p->update = p->p_datapoint[best]; /* struct copy */
|
---|
524 | slew_time();
|
---|
525 |
|
---|
526 | for (i = 0; i < NUM_DATAPOINTS; i++)
|
---|
527 | if (p->p_datapoint[i].d_rcv_time <= p->p_datapoint[best].d_rcv_time)
|
---|
528 | p->p_datapoint[i].d_good = 0;
|
---|
529 | }
|
---|
530 |
|
---|
531 | static unsigned
|
---|
532 | scale_interval(unsigned requested)
|
---|
533 | {
|
---|
534 | unsigned interval, r;
|
---|
535 | interval = requested * G.scale;
|
---|
536 | r = (unsigned)random() % (unsigned)(MAX(5, interval / 10));
|
---|
537 | return (interval + r);
|
---|
538 | }
|
---|
539 | static void
|
---|
540 | recv_and_process_peer_pkt(peer_t *p)
|
---|
541 | {
|
---|
542 | ssize_t size;
|
---|
543 | msg_t msg;
|
---|
544 | double T1, T2, T3, T4;
|
---|
545 | unsigned interval;
|
---|
546 | datapoint_t *datapoint;
|
---|
547 |
|
---|
548 | /* We can recvfrom here and check from.IP, but some multihomed
|
---|
549 | * ntp servers reply from their *other IP*.
|
---|
550 | * TODO: maybe we should check at least what we can: from.port == 123?
|
---|
551 | */
|
---|
552 | size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
|
---|
553 | if (size == -1) {
|
---|
554 | bb_perror_msg("recv(%s) error", p->p_dotted);
|
---|
555 | if (errno == EHOSTUNREACH || errno == EHOSTDOWN
|
---|
556 | || errno == ENETUNREACH || errno == ENETDOWN
|
---|
557 | || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
|
---|
558 | || errno == EAGAIN
|
---|
559 | ) {
|
---|
560 | //TODO: always do this?
|
---|
561 | set_next(p, error_interval());
|
---|
562 | goto close_sock;
|
---|
563 | }
|
---|
564 | xfunc_die();
|
---|
565 | }
|
---|
566 |
|
---|
567 | if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
|
---|
568 | bb_error_msg("malformed packet received from %s", p->p_dotted);
|
---|
569 | goto bail;
|
---|
570 | }
|
---|
571 |
|
---|
572 | if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
|
---|
573 | || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
|
---|
574 | ) {
|
---|
575 | goto bail;
|
---|
576 | }
|
---|
577 |
|
---|
578 | if ((msg.m_status & LI_ALARM) == LI_ALARM
|
---|
579 | || msg.m_stratum == 0
|
---|
580 | || msg.m_stratum > NTP_MAXSTRATUM
|
---|
581 | ) {
|
---|
582 | // TODO: stratum 0 responses may have commands in 32-bit m_refid field:
|
---|
583 | // "DENY", "RSTR" - peer does not like us at all
|
---|
584 | // "RATE" - peer is overloaded, reduce polling freq
|
---|
585 | interval = error_interval();
|
---|
586 | bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
|
---|
587 | goto close_sock;
|
---|
588 | }
|
---|
589 |
|
---|
590 | /*
|
---|
591 | * From RFC 2030 (with a correction to the delay math):
|
---|
592 | *
|
---|
593 | * Timestamp Name ID When Generated
|
---|
594 | * ------------------------------------------------------------
|
---|
595 | * Originate Timestamp T1 time request sent by client
|
---|
596 | * Receive Timestamp T2 time request received by server
|
---|
597 | * Transmit Timestamp T3 time reply sent by server
|
---|
598 | * Destination Timestamp T4 time reply received by client
|
---|
599 | *
|
---|
600 | * The roundtrip delay and local clock offset are defined as
|
---|
601 | *
|
---|
602 | * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
|
---|
603 | */
|
---|
604 | T1 = p->p_xmttime;
|
---|
605 | T2 = lfp_to_d(msg.m_rectime);
|
---|
606 | T3 = lfp_to_d(msg.m_xmttime);
|
---|
607 | T4 = gettime1900d();
|
---|
608 |
|
---|
609 | datapoint = &p->p_datapoint[p->p_datapoint_idx];
|
---|
610 |
|
---|
611 | datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
|
---|
612 | datapoint->d_delay = (T4 - T1) - (T3 - T2);
|
---|
613 | if (datapoint->d_delay < 0) {
|
---|
614 | bb_error_msg("reply from %s: negative delay %f", p->p_dotted, datapoint->d_delay);
|
---|
615 | interval = error_interval();
|
---|
616 | set_next(p, interval);
|
---|
617 | goto close_sock;
|
---|
618 | }
|
---|
619 | //UNUSED: datapoint->d_error = (T2 - T1) - (T3 - T4);
|
---|
620 | datapoint->d_rcv_time = (time_t)(T4 - OFFSET_1900_1970); /* = time(NULL); */
|
---|
621 | datapoint->d_good = 1;
|
---|
622 |
|
---|
623 | datapoint->d_leap = (msg.m_status & LI_MASK);
|
---|
624 | //UNUSED: datapoint->o_precision = msg.m_precision_exp;
|
---|
625 | //UNUSED: datapoint->o_rootdelay = sfp_to_d(msg.m_rootdelay);
|
---|
626 | //UNUSED: datapoint->o_rootdispersion = sfp_to_d(msg.m_dispersion);
|
---|
627 | //UNUSED: datapoint->d_refid = ntohl(msg.m_refid);
|
---|
628 | datapoint->d_refid4 = msg.m_xmttime.fractionl;
|
---|
629 | //UNUSED: datapoint->o_reftime = lfp_to_d(msg.m_reftime);
|
---|
630 | //UNUSED: datapoint->o_poll = msg.m_ppoll;
|
---|
631 | datapoint->d_stratum = msg.m_stratum;
|
---|
632 |
|
---|
633 | if (p->p_trustlevel < TRUSTLEVEL_PATHETIC)
|
---|
634 | interval = scale_interval(INTERVAL_QUERY_PATHETIC);
|
---|
635 | else if (p->p_trustlevel < TRUSTLEVEL_AGRESSIVE)
|
---|
636 | interval = scale_interval(INTERVAL_QUERY_AGRESSIVE);
|
---|
637 | else
|
---|
638 | interval = scale_interval(INTERVAL_QUERY_NORMAL);
|
---|
639 |
|
---|
640 | set_next(p, interval);
|
---|
641 |
|
---|
642 | /* Every received reply which we do not discard increases trust */
|
---|
643 | if (p->p_trustlevel < TRUSTLEVEL_MAX) {
|
---|
644 | p->p_trustlevel++;
|
---|
645 | if (p->p_trustlevel == TRUSTLEVEL_BADPEER)
|
---|
646 | bb_error_msg("peer %s now valid", p->p_dotted);
|
---|
647 | }
|
---|
648 |
|
---|
649 | if (G.verbose)
|
---|
650 | bb_error_msg("reply from %s: offset %f delay %f, next query in %us", p->p_dotted,
|
---|
651 | datapoint->d_offset, datapoint->d_delay, interval);
|
---|
652 |
|
---|
653 | update_peer_data(p);
|
---|
654 | //TODO: do it after all peers had a chance to return at least one reply?
|
---|
655 | step_time_once(datapoint->d_offset);
|
---|
656 |
|
---|
657 | p->p_datapoint_idx++;
|
---|
658 | if (p->p_datapoint_idx >= NUM_DATAPOINTS)
|
---|
659 | p->p_datapoint_idx = 0;
|
---|
660 |
|
---|
661 | close_sock:
|
---|
662 | /* We do not expect any more packets from this peer for now.
|
---|
663 | * Closing the socket informs kernel about it.
|
---|
664 | * We open a new socket when we send a new query.
|
---|
665 | */
|
---|
666 | close(p->p_fd);
|
---|
667 | p->p_fd = -1;
|
---|
668 | bail:
|
---|
669 | return;
|
---|
670 | }
|
---|
671 |
|
---|
672 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
673 | static void
|
---|
674 | recv_and_process_client_pkt(void /*int fd*/)
|
---|
675 | {
|
---|
676 | ssize_t size;
|
---|
677 | uint8_t version;
|
---|
678 | double rectime;
|
---|
679 | len_and_sockaddr *to;
|
---|
680 | struct sockaddr *from;
|
---|
681 | msg_t msg;
|
---|
682 | uint8_t query_status;
|
---|
683 | uint8_t query_ppoll;
|
---|
684 | l_fixedpt_t query_xmttime;
|
---|
685 |
|
---|
686 | to = get_sock_lsa(G.listen_fd);
|
---|
687 | from = xzalloc(to->len);
|
---|
688 |
|
---|
689 | size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
|
---|
690 | if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
|
---|
691 | char *addr;
|
---|
692 | if (size < 0) {
|
---|
693 | if (errno == EAGAIN)
|
---|
694 | goto bail;
|
---|
695 | bb_perror_msg_and_die("recv");
|
---|
696 | }
|
---|
697 | addr = xmalloc_sockaddr2dotted_noport(from);
|
---|
698 | bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
|
---|
699 | free(addr);
|
---|
700 | goto bail;
|
---|
701 | }
|
---|
702 |
|
---|
703 | query_status = msg.m_status;
|
---|
704 | query_ppoll = msg.m_ppoll;
|
---|
705 | query_xmttime = msg.m_xmttime;
|
---|
706 |
|
---|
707 | /* Build a reply packet */
|
---|
708 | memset(&msg, 0, sizeof(msg));
|
---|
709 | msg.m_status = G.synced ? G.leap : LI_ALARM;
|
---|
710 | msg.m_status |= (query_status & VERSION_MASK);
|
---|
711 | msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
|
---|
712 | MODE_SERVER : MODE_SYM_PAS;
|
---|
713 | msg.m_stratum = G.stratum;
|
---|
714 | msg.m_ppoll = query_ppoll;
|
---|
715 | msg.m_precision_exp = G_precision_exp;
|
---|
716 | rectime = gettime1900d();
|
---|
717 | msg.m_xmttime = msg.m_rectime = d_to_lfp(rectime);
|
---|
718 | msg.m_reftime = d_to_lfp(G.reftime);
|
---|
719 | //msg.m_xmttime = d_to_lfp(gettime1900d()); // = msg.m_rectime
|
---|
720 | msg.m_orgtime = query_xmttime;
|
---|
721 | msg.m_rootdelay = d_to_sfp(G.rootdelay);
|
---|
722 | version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
|
---|
723 | msg.m_refid = (version > (3 << VERSION_SHIFT)) ? G.refid4 : G.refid;
|
---|
724 |
|
---|
725 | /* We reply from the local address packet was sent to,
|
---|
726 | * this makes to/from look swapped here: */
|
---|
727 | do_sendto(G.listen_fd,
|
---|
728 | /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
|
---|
729 | &msg, size);
|
---|
730 |
|
---|
731 | bail:
|
---|
732 | free(to);
|
---|
733 | free(from);
|
---|
734 | }
|
---|
735 | #endif
|
---|
736 |
|
---|
737 | /* Upstream ntpd's options:
|
---|
738 | *
|
---|
739 | * -4 Force DNS resolution of host names to the IPv4 namespace.
|
---|
740 | * -6 Force DNS resolution of host names to the IPv6 namespace.
|
---|
741 | * -a Require cryptographic authentication for broadcast client,
|
---|
742 | * multicast client and symmetric passive associations.
|
---|
743 | * This is the default.
|
---|
744 | * -A Do not require cryptographic authentication for broadcast client,
|
---|
745 | * multicast client and symmetric passive associations.
|
---|
746 | * This is almost never a good idea.
|
---|
747 | * -b Enable the client to synchronize to broadcast servers.
|
---|
748 | * -c conffile
|
---|
749 | * Specify the name and path of the configuration file,
|
---|
750 | * default /etc/ntp.conf
|
---|
751 | * -d Specify debugging mode. This option may occur more than once,
|
---|
752 | * with each occurrence indicating greater detail of display.
|
---|
753 | * -D level
|
---|
754 | * Specify debugging level directly.
|
---|
755 | * -f driftfile
|
---|
756 | * Specify the name and path of the frequency file.
|
---|
757 | * This is the same operation as the "driftfile FILE"
|
---|
758 | * configuration command.
|
---|
759 | * -g Normally, ntpd exits with a message to the system log
|
---|
760 | * if the offset exceeds the panic threshold, which is 1000 s
|
---|
761 | * by default. This option allows the time to be set to any value
|
---|
762 | * without restriction; however, this can happen only once.
|
---|
763 | * If the threshold is exceeded after that, ntpd will exit
|
---|
764 | * with a message to the system log. This option can be used
|
---|
765 | * with the -q and -x options. See the tinker command for other options.
|
---|
766 | * -i jaildir
|
---|
767 | * Chroot the server to the directory jaildir. This option also implies
|
---|
768 | * that the server attempts to drop root privileges at startup
|
---|
769 | * (otherwise, chroot gives very little additional security).
|
---|
770 | * You may need to also specify a -u option.
|
---|
771 | * -k keyfile
|
---|
772 | * Specify the name and path of the symmetric key file,
|
---|
773 | * default /etc/ntp/keys. This is the same operation
|
---|
774 | * as the "keys FILE" configuration command.
|
---|
775 | * -l logfile
|
---|
776 | * Specify the name and path of the log file. The default
|
---|
777 | * is the system log file. This is the same operation as
|
---|
778 | * the "logfile FILE" configuration command.
|
---|
779 | * -L Do not listen to virtual IPs. The default is to listen.
|
---|
780 | * -n Don't fork.
|
---|
781 | * -N To the extent permitted by the operating system,
|
---|
782 | * run the ntpd at the highest priority.
|
---|
783 | * -p pidfile
|
---|
784 | * Specify the name and path of the file used to record the ntpd
|
---|
785 | * process ID. This is the same operation as the "pidfile FILE"
|
---|
786 | * configuration command.
|
---|
787 | * -P priority
|
---|
788 | * To the extent permitted by the operating system,
|
---|
789 | * run the ntpd at the specified priority.
|
---|
790 | * -q Exit the ntpd just after the first time the clock is set.
|
---|
791 | * This behavior mimics that of the ntpdate program, which is
|
---|
792 | * to be retired. The -g and -x options can be used with this option.
|
---|
793 | * Note: The kernel time discipline is disabled with this option.
|
---|
794 | * -r broadcastdelay
|
---|
795 | * Specify the default propagation delay from the broadcast/multicast
|
---|
796 | * server to this client. This is necessary only if the delay
|
---|
797 | * cannot be computed automatically by the protocol.
|
---|
798 | * -s statsdir
|
---|
799 | * Specify the directory path for files created by the statistics
|
---|
800 | * facility. This is the same operation as the "statsdir DIR"
|
---|
801 | * configuration command.
|
---|
802 | * -t key
|
---|
803 | * Add a key number to the trusted key list. This option can occur
|
---|
804 | * more than once.
|
---|
805 | * -u user[:group]
|
---|
806 | * Specify a user, and optionally a group, to switch to.
|
---|
807 | * -v variable
|
---|
808 | * -V variable
|
---|
809 | * Add a system variable listed by default.
|
---|
810 | * -x Normally, the time is slewed if the offset is less than the step
|
---|
811 | * threshold, which is 128 ms by default, and stepped if above
|
---|
812 | * the threshold. This option sets the threshold to 600 s, which is
|
---|
813 | * well within the accuracy window to set the clock manually.
|
---|
814 | * Note: since the slew rate of typical Unix kernels is limited
|
---|
815 | * to 0.5 ms/s, each second of adjustment requires an amortization
|
---|
816 | * interval of 2000 s. Thus, an adjustment as much as 600 s
|
---|
817 | * will take almost 14 days to complete. This option can be used
|
---|
818 | * with the -g and -q options. See the tinker command for other options.
|
---|
819 | * Note: The kernel time discipline is disabled with this option.
|
---|
820 | */
|
---|
821 |
|
---|
822 | /* By doing init in a separate function we decrease stack usage
|
---|
823 | * in main loop.
|
---|
824 | */
|
---|
825 | static NOINLINE void ntp_init(char **argv)
|
---|
826 | {
|
---|
827 | unsigned opts;
|
---|
828 | llist_t *peers;
|
---|
829 |
|
---|
830 | srandom(getpid());
|
---|
831 |
|
---|
832 | if (getuid())
|
---|
833 | bb_error_msg_and_die(bb_msg_you_must_be_root);
|
---|
834 |
|
---|
835 | peers = NULL;
|
---|
836 | opt_complementary = "dd:p::"; /* d: counter, p: list */
|
---|
837 | opts = getopt32(argv,
|
---|
838 | "nqNx" /* compat */
|
---|
839 | "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
|
---|
840 | "d" /* compat */
|
---|
841 | "46aAbgL", /* compat, ignored */
|
---|
842 | &peers, &G.verbose);
|
---|
843 | if (!(opts & (OPT_p|OPT_l)))
|
---|
844 | bb_show_usage();
|
---|
845 | if (opts & OPT_x) /* disable stepping, only slew is allowed */
|
---|
846 | G.time_was_stepped = 1;
|
---|
847 | while (peers)
|
---|
848 | add_peers(llist_pop(&peers));
|
---|
849 | if (!(opts & OPT_n)) {
|
---|
850 | bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
|
---|
851 | logmode = LOGMODE_NONE;
|
---|
852 | }
|
---|
853 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
854 | G.listen_fd = -1;
|
---|
855 | if (opts & OPT_l) {
|
---|
856 | G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
|
---|
857 | socket_want_pktinfo(G.listen_fd);
|
---|
858 | setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
|
---|
859 | }
|
---|
860 | #endif
|
---|
861 | /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
|
---|
862 | if (opts & OPT_N)
|
---|
863 | setpriority(PRIO_PROCESS, 0, -15);
|
---|
864 |
|
---|
865 | /* Set some globals */
|
---|
866 | #if 0
|
---|
867 | /* With constant b = 100, G.precision_exp is also constant -6.
|
---|
868 | * Uncomment this and you'll see */
|
---|
869 | {
|
---|
870 | int prec = 0;
|
---|
871 | int b;
|
---|
872 | # if 0
|
---|
873 | struct timespec tp;
|
---|
874 | /* We can use sys_clock_getres but assuming 10ms tick should be fine */
|
---|
875 | clock_getres(CLOCK_REALTIME, &tp);
|
---|
876 | tp.tv_sec = 0;
|
---|
877 | tp.tv_nsec = 10000000;
|
---|
878 | b = 1000000000 / tp.tv_nsec; /* convert to Hz */
|
---|
879 | # else
|
---|
880 | b = 100; /* b = 1000000000/10000000 = 100 */
|
---|
881 | # endif
|
---|
882 | while (b > 1)
|
---|
883 | prec--, b >>= 1;
|
---|
884 | //G.precision_exp = prec;
|
---|
885 | bb_error_msg("G.precision_exp:%d", prec); /* -6 */
|
---|
886 | }
|
---|
887 | #endif
|
---|
888 | G.scale = 1;
|
---|
889 |
|
---|
890 | bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo);
|
---|
891 | bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN);
|
---|
892 | }
|
---|
893 |
|
---|
894 | int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
895 | int ntpd_main(int argc UNUSED_PARAM, char **argv)
|
---|
896 | {
|
---|
897 | struct globals g;
|
---|
898 | struct pollfd *pfd;
|
---|
899 | peer_t **idx2peer;
|
---|
900 |
|
---|
901 | memset(&g, 0, sizeof(g));
|
---|
902 | SET_PTR_TO_GLOBALS(&g);
|
---|
903 |
|
---|
904 | ntp_init(argv);
|
---|
905 |
|
---|
906 | {
|
---|
907 | /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
|
---|
908 | unsigned cnt = g.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
|
---|
909 | idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
|
---|
910 | pfd = xzalloc(sizeof(pfd[0]) * cnt);
|
---|
911 | }
|
---|
912 |
|
---|
913 | while (!bb_got_signal) {
|
---|
914 | llist_t *item;
|
---|
915 | unsigned i, j;
|
---|
916 | unsigned sent_cnt, trial_cnt;
|
---|
917 | int nfds, timeout;
|
---|
918 | time_t cur_time, nextaction;
|
---|
919 |
|
---|
920 | /* Nothing between here and poll() blocks for any significant time */
|
---|
921 |
|
---|
922 | cur_time = time(NULL);
|
---|
923 | nextaction = cur_time + 3600;
|
---|
924 |
|
---|
925 | i = 0;
|
---|
926 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
927 | if (g.listen_fd != -1) {
|
---|
928 | pfd[0].fd = g.listen_fd;
|
---|
929 | pfd[0].events = POLLIN;
|
---|
930 | i++;
|
---|
931 | }
|
---|
932 | #endif
|
---|
933 | /* Pass over peer list, send requests, time out on receives */
|
---|
934 | sent_cnt = trial_cnt = 0;
|
---|
935 | for (item = g.ntp_peers; item != NULL; item = item->link) {
|
---|
936 | peer_t *p = (peer_t *) item->data;
|
---|
937 |
|
---|
938 | /* Overflow-safe "if (p->next_action_time <= cur_time) ..." */
|
---|
939 | if ((int)(cur_time - p->next_action_time) >= 0) {
|
---|
940 | if (p->p_fd == -1) {
|
---|
941 | /* Time to send new req */
|
---|
942 | trial_cnt++;
|
---|
943 | if (send_query_to_peer(p) == 0)
|
---|
944 | sent_cnt++;
|
---|
945 | } else {
|
---|
946 | /* Timed out waiting for reply */
|
---|
947 | close(p->p_fd);
|
---|
948 | p->p_fd = -1;
|
---|
949 | timeout = error_interval();
|
---|
950 | bb_error_msg("timed out waiting for %s, "
|
---|
951 | "next query in %us", p->p_dotted, timeout);
|
---|
952 | if (p->p_trustlevel >= TRUSTLEVEL_BADPEER) {
|
---|
953 | p->p_trustlevel /= 2;
|
---|
954 | if (p->p_trustlevel < TRUSTLEVEL_BADPEER)
|
---|
955 | bb_error_msg("peer %s now invalid", p->p_dotted);
|
---|
956 | }
|
---|
957 | set_next(p, timeout);
|
---|
958 | }
|
---|
959 | }
|
---|
960 |
|
---|
961 | if (p->next_action_time < nextaction)
|
---|
962 | nextaction = p->next_action_time;
|
---|
963 |
|
---|
964 | if (p->p_fd >= 0) {
|
---|
965 | /* Wait for reply from this peer */
|
---|
966 | pfd[i].fd = p->p_fd;
|
---|
967 | pfd[i].events = POLLIN;
|
---|
968 | idx2peer[i] = p;
|
---|
969 | i++;
|
---|
970 | }
|
---|
971 | }
|
---|
972 |
|
---|
973 | if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0)
|
---|
974 | step_time_once(0); /* no good peers, don't wait */
|
---|
975 |
|
---|
976 | timeout = nextaction - cur_time;
|
---|
977 | if (timeout < 1)
|
---|
978 | timeout = 1;
|
---|
979 |
|
---|
980 | /* Here we may block */
|
---|
981 | if (g.verbose >= 2)
|
---|
982 | bb_error_msg("poll %us, sockets:%u", timeout, i);
|
---|
983 | nfds = poll(pfd, i, timeout * 1000);
|
---|
984 | if (nfds <= 0)
|
---|
985 | continue;
|
---|
986 |
|
---|
987 | /* Process any received packets */
|
---|
988 | j = 0;
|
---|
989 | #if ENABLE_FEATURE_NTPD_SERVER
|
---|
990 | if (g.listen_fd != -1) {
|
---|
991 | if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
|
---|
992 | nfds--;
|
---|
993 | recv_and_process_client_pkt(/*g.listen_fd*/);
|
---|
994 | }
|
---|
995 | j = 1;
|
---|
996 | }
|
---|
997 | #endif
|
---|
998 | for (; nfds != 0 && j < i; j++) {
|
---|
999 | if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
|
---|
1000 | nfds--;
|
---|
1001 | recv_and_process_peer_pkt(idx2peer[j]);
|
---|
1002 | }
|
---|
1003 | }
|
---|
1004 | } /* while (!bb_got_signal) */
|
---|
1005 |
|
---|
1006 | kill_myself_with_sig(bb_got_signal);
|
---|
1007 | }
|
---|