1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * DHCP server config and lease file manipulation
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4 | *
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5 | * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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6 | *
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7 | * Licensed under GPLv2, see file LICENSE in this source tree.
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8 | */
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9 | #include <netinet/ether.h>
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10 |
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11 | #include "common.h"
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12 | #include "dhcpd.h"
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13 |
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14 | /* on these functions, make sure your datatype matches */
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15 | static int FAST_FUNC read_str(const char *line, void *arg)
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16 | {
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17 | char **dest = arg;
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18 |
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19 | free(*dest);
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20 | *dest = xstrdup(line);
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21 | return 1;
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22 | }
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23 |
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24 | static int FAST_FUNC read_u32(const char *line, void *arg)
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25 | {
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26 | *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
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27 | return errno == 0;
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28 | }
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29 |
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30 | static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
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31 | {
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32 | char *line;
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33 | char *mac_string;
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34 | char *ip_string;
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35 | struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
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36 | uint32_t nip;
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37 |
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38 | /* Read mac */
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39 | line = (char *) const_line;
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40 | mac_string = strtok_r(line, " \t", &line);
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41 | if (!mac_string || !ether_aton_r(mac_string, &mac_bytes))
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42 | return 0;
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43 |
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44 | /* Read ip */
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45 | ip_string = strtok_r(NULL, " \t", &line);
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46 | if (!ip_string || !udhcp_str2nip(ip_string, &nip))
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47 | return 0;
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48 |
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49 | add_static_lease(arg, (uint8_t*) &mac_bytes, nip);
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50 |
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51 | log_static_leases(arg);
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52 |
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53 | return 1;
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54 | }
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55 |
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56 |
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57 | struct config_keyword {
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58 | const char *keyword;
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59 | int (*handler)(const char *line, void *var) FAST_FUNC;
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60 | unsigned ofs;
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61 | const char *def;
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62 | };
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63 |
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64 | #define OFS(field) offsetof(struct server_config_t, field)
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65 |
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66 | static const struct config_keyword keywords[] = {
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67 | /* keyword handler variable address default */
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68 | {"start" , udhcp_str2nip , OFS(start_ip ), "192.168.0.20"},
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69 | {"end" , udhcp_str2nip , OFS(end_ip ), "192.168.0.254"},
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70 | {"interface" , read_str , OFS(interface ), "eth0"},
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71 | /* Avoid "max_leases value not sane" warning by setting default
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72 | * to default_end_ip - default_start_ip + 1: */
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73 | {"max_leases" , read_u32 , OFS(max_leases ), "235"},
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74 | {"auto_time" , read_u32 , OFS(auto_time ), "7200"},
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75 | {"decline_time" , read_u32 , OFS(decline_time ), "3600"},
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76 | {"conflict_time", read_u32 , OFS(conflict_time), "3600"},
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77 | {"offer_time" , read_u32 , OFS(offer_time ), "60"},
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78 | {"min_lease" , read_u32 , OFS(min_lease_sec), "60"},
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79 | {"lease_file" , read_str , OFS(lease_file ), LEASES_FILE},
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80 | {"pidfile" , read_str , OFS(pidfile ), "/var/run/udhcpd.pid"},
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81 | {"siaddr" , udhcp_str2nip , OFS(siaddr_nip ), "0.0.0.0"},
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82 | /* keywords with no defaults must be last! */
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83 | {"option" , udhcp_str2optset, OFS(options ), ""},
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84 | {"opt" , udhcp_str2optset, OFS(options ), ""},
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85 | {"notify_file" , read_str , OFS(notify_file ), NULL},
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86 | {"sname" , read_str , OFS(sname ), NULL},
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87 | {"boot_file" , read_str , OFS(boot_file ), NULL},
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88 | {"static_lease" , read_staticlease, OFS(static_leases), ""},
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89 | };
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90 | enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
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91 |
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92 | void FAST_FUNC read_config(const char *file)
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93 | {
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94 | parser_t *parser;
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95 | const struct config_keyword *k;
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96 | unsigned i;
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97 | char *token[2];
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98 |
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99 | for (i = 0; i < KWS_WITH_DEFAULTS; i++)
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100 | keywords[i].handler(keywords[i].def, (char*)&server_config + keywords[i].ofs);
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101 |
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102 | parser = config_open(file);
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103 | while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
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104 | for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
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105 | if (strcasecmp(token[0], k->keyword) == 0) {
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106 | if (!k->handler(token[1], (char*)&server_config + k->ofs)) {
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107 | bb_error_msg("can't parse line %u in %s",
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108 | parser->lineno, file);
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109 | /* reset back to the default value */
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110 | k->handler(k->def, (char*)&server_config + k->ofs);
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111 | }
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112 | break;
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113 | }
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114 | }
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115 | }
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116 | config_close(parser);
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117 |
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118 | server_config.start_ip = ntohl(server_config.start_ip);
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119 | server_config.end_ip = ntohl(server_config.end_ip);
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120 | }
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121 |
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122 | void FAST_FUNC write_leases(void)
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123 | {
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124 | int fd;
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125 | unsigned i;
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126 | leasetime_t curr;
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127 | int64_t written_at;
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128 |
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129 | fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
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130 | if (fd < 0)
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131 | return;
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132 |
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133 | curr = written_at = time(NULL);
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134 |
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135 | written_at = SWAP_BE64(written_at);
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136 | full_write(fd, &written_at, sizeof(written_at));
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137 |
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138 | for (i = 0; i < server_config.max_leases; i++) {
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139 | leasetime_t tmp_time;
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140 |
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141 | if (g_leases[i].lease_nip == 0)
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142 | continue;
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143 |
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144 | /* Screw with the time in the struct, for easier writing */
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145 | tmp_time = g_leases[i].expires;
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146 |
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147 | g_leases[i].expires -= curr;
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148 | if ((signed_leasetime_t) g_leases[i].expires < 0)
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149 | g_leases[i].expires = 0;
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150 | g_leases[i].expires = htonl(g_leases[i].expires);
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151 |
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152 | /* No error check. If the file gets truncated,
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153 | * we lose some leases on restart. Oh well. */
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154 | full_write(fd, &g_leases[i], sizeof(g_leases[i]));
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155 |
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156 | /* Then restore it when done */
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157 | g_leases[i].expires = tmp_time;
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158 | }
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159 | close(fd);
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160 |
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161 | if (server_config.notify_file) {
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162 | char *argv[3];
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163 | argv[0] = server_config.notify_file;
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164 | argv[1] = server_config.lease_file;
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165 | argv[2] = NULL;
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166 | spawn_and_wait(argv);
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167 | }
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168 | }
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169 |
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170 | void FAST_FUNC read_leases(const char *file)
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171 | {
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172 | struct dyn_lease lease;
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173 | int64_t written_at, time_passed;
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174 | int fd;
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175 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
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176 | unsigned i = 0;
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177 | #endif
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178 |
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179 | fd = open_or_warn(file, O_RDONLY);
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180 | if (fd < 0)
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181 | return;
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182 |
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183 | if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
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184 | goto ret;
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185 | written_at = SWAP_BE64(written_at);
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186 |
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187 | time_passed = time(NULL) - written_at;
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188 | /* Strange written_at, or lease file from old version of udhcpd
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189 | * which had no "written_at" field? */
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190 | if ((uint64_t)time_passed > 12 * 60 * 60)
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191 | goto ret;
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192 |
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193 | while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
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194 | uint32_t y = ntohl(lease.lease_nip);
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195 | if (y >= server_config.start_ip && y <= server_config.end_ip) {
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196 | signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
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197 | uint32_t static_nip;
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198 |
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199 | if (expires <= 0)
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200 | /* We keep expired leases: add_lease() will add
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201 | * a lease with 0 seconds remaining.
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202 | * Fewer IP address changes this way for mass reboot scenario.
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203 | */
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204 | expires = 0;
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205 |
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206 | /* Check if there is a different static lease for this IP or MAC */
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207 | static_nip = get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
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208 | if (static_nip) {
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209 | /* NB: we do not add lease even if static_nip == lease.lease_nip.
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210 | */
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211 | continue;
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212 | }
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213 | if (is_nip_reserved(server_config.static_leases, lease.lease_nip))
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214 | continue;
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215 |
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216 | /* NB: add_lease takes "relative time", IOW,
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217 | * lease duration, not lease deadline. */
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218 | if (add_lease(lease.lease_mac, lease.lease_nip,
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219 | expires,
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220 | lease.hostname, sizeof(lease.hostname)
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221 | ) == 0
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222 | ) {
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223 | bb_error_msg("too many leases while loading %s", file);
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224 | break;
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225 | }
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226 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
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227 | i++;
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228 | #endif
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229 | }
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230 | }
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231 | log1("read %d leases", i);
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232 | ret:
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233 | close(fd);
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234 | }
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