[1765] | 1 | /* vi: set sw=4 ts=4: */
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[821] | 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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[1765] | 13 | #include <syslog.h>
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| 14 | #include "common.h"
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[821] | 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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[1765] | 24 | int udhcpd_main(int argc, char **argv);
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| 25 | int udhcpd_main(int argc, char **argv)
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[821] | 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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[1765] | 33 | unsigned timeout_end;
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| 34 | unsigned num_ips;
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| 35 | unsigned opt;
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[821] | 36 | struct option_set *option;
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| 37 | struct dhcpOfferedAddr *lease, static_lease;
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| 38 |
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[1765] | 39 | opt = getopt32(argv, "fS");
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| 40 | argv += optind;
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[821] | 41 |
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[1765] | 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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[821] | 46 |
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[1765] | 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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[821] | 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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[1765] | 75 | num_ips = server_config.end_ip - server_config.start_ip + 1;
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[821] | 76 | if (server_config.max_leases > num_ips) {
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[1765] | 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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[821] | 79 | server_config.max_leases = num_ips;
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| 80 | }
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| 81 |
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[1765] | 82 | leases = xzalloc(server_config.max_leases * sizeof(*leases));
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[821] | 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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[1765] | 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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[821] | 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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[1765] | 94 | timeout_end = monotonic_sec() + server_config.auto_time;
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| 95 | while (1) { /* loop until universe collapses */
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[821] | 96 |
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[1765] | 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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[821] | 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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[1765] | 104 | tv.tv_sec = timeout_end - monotonic_sec();
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[821] | 105 | tv.tv_usec = 0;
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| 106 | }
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[1765] | 107 | retval = 0;
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[821] | 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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[1765] | 111 | }
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[821] | 112 | if (retval == 0) {
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| 113 | write_leases();
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[1765] | 114 | timeout_end = monotonic_sec() + server_config.auto_time;
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[821] | 115 | continue;
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[1765] | 116 | }
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| 117 | if (retval < 0 && errno != EINTR) {
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| 118 | DEBUG("error on select");
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[821] | 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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[1765] | 124 | bb_info_msg("Received a SIGUSR1");
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[821] | 125 | write_leases();
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| 126 | /* why not just reset the timeout, eh */
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[1765] | 127 | timeout_end = monotonic_sec() + server_config.auto_time;
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[821] | 128 | continue;
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| 129 | case SIGTERM:
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[1765] | 130 | bb_info_msg("Received a SIGTERM");
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| 131 | goto ret0;
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[821] | 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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[1765] | 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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[821] | 138 | if (bytes == -1 && errno != EINTR) {
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[1765] | 139 | DEBUG("error on read, %s, reopening socket", strerror(errno));
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[821] | 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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[1765] | 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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[821] | 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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[1765] | 155 | if (static_lease_ip) {
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| 156 | bb_info_msg("Found static lease: %x", static_lease_ip);
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[821] | 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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[1765] | 163 | } else {
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| 164 | lease = find_lease_by_chaddr(packet.chaddr);
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[821] | 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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[1765] | 169 | DEBUG("Received DISCOVER");
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[821] | 170 |
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| 171 | if (sendOffer(&packet) < 0) {
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[1765] | 172 | bb_error_msg("send OFFER failed");
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[821] | 173 | }
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| 174 | break;
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| 175 | case DHCPREQUEST:
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[1765] | 176 | DEBUG("received REQUEST");
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[821] | 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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[1765] | 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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[821] | 191 | sendACK(&packet, lease->yiaddr);
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| 192 | }
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[1765] | 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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[821] | 202 | } else {
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[1765] | 203 | /* don't know what to do!!!! */
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| 204 | sendNAK(&packet);
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[821] | 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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[1765] | 213 | lease = find_lease_by_yiaddr(requested_align);
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| 214 | if (lease) {
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[821] | 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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[1765] | 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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[821] | 230 |
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| 231 | } else {
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[1765] | 232 | /* RENEWING or REBINDING State */
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[821] | 233 | }
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| 234 | break;
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| 235 | case DHCPDECLINE:
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[1765] | 236 | DEBUG("Received DECLINE");
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[821] | 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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[1765] | 243 | DEBUG("Received RELEASE");
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| 244 | if (lease)
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| 245 | lease->expires = time(0);
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[821] | 246 | break;
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| 247 | case DHCPINFORM:
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[1765] | 248 | DEBUG("Received INFORM");
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[821] | 249 | send_inform(&packet);
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| 250 | break;
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| 251 | default:
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[1765] | 252 | bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
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[821] | 253 | }
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| 254 | }
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[1765] | 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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[821] | 261 | }
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