1 | /* vi: set sw=4 ts=4: */
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2 | /* dhcpd.c
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3 | *
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4 | * udhcp Server
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5 | * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
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6 | * Chris Trew <ctrew@moreton.com.au>
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7 | *
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8 | * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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9 | *
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10 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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11 | */
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12 |
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13 | #include <syslog.h>
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14 | #include "common.h"
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15 | #include "dhcpd.h"
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16 | #include "options.h"
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17 |
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18 |
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19 | /* globals */
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20 | struct dhcpOfferedAddr *leases;
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21 | struct server_config_t server_config;
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22 |
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23 |
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24 | int udhcpd_main(int argc, char **argv);
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25 | int udhcpd_main(int argc, char **argv)
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26 | {
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27 | fd_set rfds;
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28 | struct timeval tv;
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29 | int server_socket = -1, bytes, retval, max_sock;
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30 | struct dhcpMessage packet;
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31 | uint8_t *state, *server_id, *requested;
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32 | uint32_t server_id_align, requested_align, static_lease_ip;
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33 | unsigned timeout_end;
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34 | unsigned num_ips;
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35 | unsigned opt;
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36 | struct option_set *option;
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37 | struct dhcpOfferedAddr *lease, static_lease;
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38 |
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39 | opt = getopt32(argv, "fS");
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40 | argv += optind;
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41 |
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42 | if (!(opt & 1)) { /* no -f */
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43 | bb_daemonize_or_rexec(0, argv);
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44 | logmode &= ~LOGMODE_STDIO;
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45 | }
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46 |
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47 | if (opt & 2) { /* -S */
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48 | openlog(applet_name, LOG_PID, LOG_LOCAL0);
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49 | logmode |= LOGMODE_SYSLOG;
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50 | }
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51 |
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52 | /* Would rather not do read_config before daemonization -
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53 | * otherwise NOMMU machines will parse config twice */
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54 | read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
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55 |
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56 | /* Make sure fd 0,1,2 are open */
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57 | bb_sanitize_stdio();
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58 | /* Equivalent of doing a fflush after every \n */
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59 | setlinebuf(stdout);
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60 |
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61 | /* Create pidfile */
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62 | write_pidfile(server_config.pidfile);
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63 | /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
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64 |
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65 | bb_info_msg("%s (v%s) started", applet_name, BB_VER);
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66 |
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67 | option = find_option(server_config.options, DHCP_LEASE_TIME);
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68 | server_config.lease = LEASE_TIME;
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69 | if (option) {
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70 | memcpy(&server_config.lease, option->data + 2, 4);
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71 | server_config.lease = ntohl(server_config.lease);
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72 | }
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73 |
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74 | /* Sanity check */
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75 | num_ips = server_config.end_ip - server_config.start_ip + 1;
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76 | if (server_config.max_leases > num_ips) {
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77 | bb_error_msg("max_leases=%u is too big, setting to %u",
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78 | (unsigned)server_config.max_leases, num_ips);
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79 | server_config.max_leases = num_ips;
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80 | }
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81 |
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82 | leases = xzalloc(server_config.max_leases * sizeof(*leases));
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83 | read_leases(server_config.lease_file);
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84 |
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85 | if (read_interface(server_config.interface, &server_config.ifindex,
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86 | &server_config.server, server_config.arp)) {
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87 | retval = 1;
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88 | goto ret;
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89 | }
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90 |
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91 | /* Setup the signal pipe */
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92 | udhcp_sp_setup();
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93 |
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94 | timeout_end = monotonic_sec() + server_config.auto_time;
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95 | while (1) { /* loop until universe collapses */
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96 |
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97 | if (server_socket < 0) {
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98 | server_socket = listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
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99 | server_config.interface);
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100 | }
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101 |
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102 | max_sock = udhcp_sp_fd_set(&rfds, server_socket);
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103 | if (server_config.auto_time) {
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104 | tv.tv_sec = timeout_end - monotonic_sec();
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105 | tv.tv_usec = 0;
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106 | }
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107 | retval = 0;
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108 | if (!server_config.auto_time || tv.tv_sec > 0) {
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109 | retval = select(max_sock + 1, &rfds, NULL, NULL,
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110 | server_config.auto_time ? &tv : NULL);
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111 | }
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112 | if (retval == 0) {
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113 | write_leases();
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114 | timeout_end = monotonic_sec() + server_config.auto_time;
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115 | continue;
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116 | }
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117 | if (retval < 0 && errno != EINTR) {
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118 | DEBUG("error on select");
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119 | continue;
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120 | }
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121 |
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122 | switch (udhcp_sp_read(&rfds)) {
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123 | case SIGUSR1:
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124 | bb_info_msg("Received a SIGUSR1");
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125 | write_leases();
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126 | /* why not just reset the timeout, eh */
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127 | timeout_end = monotonic_sec() + server_config.auto_time;
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128 | continue;
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129 | case SIGTERM:
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130 | bb_info_msg("Received a SIGTERM");
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131 | goto ret0;
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132 | case 0: break; /* no signal */
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133 | default: continue; /* signal or error (probably EINTR) */
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134 | }
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135 |
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136 | bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */
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137 | if (bytes < 0) {
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138 | if (bytes == -1 && errno != EINTR) {
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139 | DEBUG("error on read, %s, reopening socket", strerror(errno));
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140 | close(server_socket);
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141 | server_socket = -1;
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142 | }
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143 | continue;
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144 | }
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145 |
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146 | state = get_option(&packet, DHCP_MESSAGE_TYPE);
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147 | if (state == NULL) {
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148 | bb_error_msg("cannot get option from packet, ignoring");
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149 | continue;
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150 | }
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151 |
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152 | /* Look for a static lease */
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153 | static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
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154 |
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155 | if (static_lease_ip) {
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156 | bb_info_msg("Found static lease: %x", static_lease_ip);
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157 |
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158 | memcpy(&static_lease.chaddr, &packet.chaddr, 16);
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159 | static_lease.yiaddr = static_lease_ip;
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160 | static_lease.expires = 0;
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161 |
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162 | lease = &static_lease;
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163 | } else {
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164 | lease = find_lease_by_chaddr(packet.chaddr);
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165 | }
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166 |
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167 | switch (state[0]) {
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168 | case DHCPDISCOVER:
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169 | DEBUG("Received DISCOVER");
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170 |
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171 | if (sendOffer(&packet) < 0) {
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172 | bb_error_msg("send OFFER failed");
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173 | }
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174 | break;
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175 | case DHCPREQUEST:
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176 | DEBUG("received REQUEST");
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177 |
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178 | requested = get_option(&packet, DHCP_REQUESTED_IP);
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179 | server_id = get_option(&packet, DHCP_SERVER_ID);
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180 |
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181 | if (requested) memcpy(&requested_align, requested, 4);
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182 | if (server_id) memcpy(&server_id_align, server_id, 4);
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183 |
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184 | if (lease) {
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185 | if (server_id) {
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186 | /* SELECTING State */
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187 | DEBUG("server_id = %08x", ntohl(server_id_align));
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188 | if (server_id_align == server_config.server && requested
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189 | && requested_align == lease->yiaddr
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190 | ) {
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191 | sendACK(&packet, lease->yiaddr);
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192 | }
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193 | } else if (requested) {
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194 | /* INIT-REBOOT State */
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195 | if (lease->yiaddr == requested_align)
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196 | sendACK(&packet, lease->yiaddr);
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197 | else
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198 | sendNAK(&packet);
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199 | } else if (lease->yiaddr == packet.ciaddr) {
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200 | /* RENEWING or REBINDING State */
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201 | sendACK(&packet, lease->yiaddr);
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202 | } else {
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203 | /* don't know what to do!!!! */
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204 | sendNAK(&packet);
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205 | }
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206 |
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207 | /* what to do if we have no record of the client */
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208 | } else if (server_id) {
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209 | /* SELECTING State */
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210 |
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211 | } else if (requested) {
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212 | /* INIT-REBOOT State */
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213 | lease = find_lease_by_yiaddr(requested_align);
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214 | if (lease) {
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215 | if (lease_expired(lease)) {
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216 | /* probably best if we drop this lease */
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217 | memset(lease->chaddr, 0, 16);
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218 | /* make some contention for this address */
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219 | } else
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220 | sendNAK(&packet);
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221 | } else {
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222 | uint32_t r = ntohl(requested_align);
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223 | if (r < server_config.start_ip
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224 | || r > server_config.end_ip
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225 | ) {
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226 | sendNAK(&packet);
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227 | }
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228 | /* else remain silent */
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229 | }
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230 |
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231 | } else {
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232 | /* RENEWING or REBINDING State */
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233 | }
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234 | break;
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235 | case DHCPDECLINE:
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236 | DEBUG("Received DECLINE");
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237 | if (lease) {
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238 | memset(lease->chaddr, 0, 16);
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239 | lease->expires = time(0) + server_config.decline_time;
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240 | }
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241 | break;
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242 | case DHCPRELEASE:
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243 | DEBUG("Received RELEASE");
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244 | if (lease)
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245 | lease->expires = time(0);
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246 | break;
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247 | case DHCPINFORM:
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248 | DEBUG("Received INFORM");
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249 | send_inform(&packet);
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250 | break;
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251 | default:
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252 | bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
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253 | }
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254 | }
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255 | ret0:
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256 | retval = 0;
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257 | ret:
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258 | /*if (server_config.pidfile) - server_config.pidfile is never NULL */
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259 | remove_pidfile(server_config.pidfile);
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260 | return retval;
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261 | }
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