297 lines
7.6 KiB
C
297 lines
7.6 KiB
C
/* vi: set sw=4 ts=4: */
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/* dhcpd.c
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*
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* udhcp Server
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* Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
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* Chris Trew <ctrew@moreton.com.au>
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*
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* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <syslog.h>
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#include "common.h"
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#include "dhcpc.h"
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#include "dhcpd.h"
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#include "options.h"
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/* globals */
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struct dyn_lease *g_leases;
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/* struct server_config_t server_config is in bb_common_bufsiz1 */
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int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int udhcpd_main(int argc UNUSED_PARAM, char **argv)
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{
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fd_set rfds;
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int server_socket = -1, retval, max_sock;
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struct dhcp_packet packet;
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uint8_t *state;
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uint32_t static_lease_ip;
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unsigned timeout_end;
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unsigned num_ips;
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unsigned opt;
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struct option_set *option;
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struct dyn_lease *lease, fake_lease;
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IF_FEATURE_UDHCP_PORT(char *str_P;)
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#if ENABLE_FEATURE_UDHCP_PORT
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SERVER_PORT = 67;
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CLIENT_PORT = 68;
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#endif
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#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
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opt_complementary = "vv";
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#endif
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opt = getopt32(argv, "fSv"
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IF_FEATURE_UDHCP_PORT("P:", &str_P)
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#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
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, &dhcp_verbose
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#endif
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);
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argv += optind;
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if (!(opt & 1)) { /* no -f */
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bb_daemonize_or_rexec(0, argv);
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logmode = LOGMODE_NONE;
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}
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if (opt & 2) { /* -S */
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openlog(applet_name, LOG_PID, LOG_DAEMON);
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logmode |= LOGMODE_SYSLOG;
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}
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#if ENABLE_FEATURE_UDHCP_PORT
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if (opt & 4) { /* -P */
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SERVER_PORT = xatou16(str_P);
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CLIENT_PORT = SERVER_PORT + 1;
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}
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#endif
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/* Would rather not do read_config before daemonization -
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* otherwise NOMMU machines will parse config twice */
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read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
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/* Make sure fd 0,1,2 are open */
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bb_sanitize_stdio();
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/* Equivalent of doing a fflush after every \n */
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setlinebuf(stdout);
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/* Create pidfile */
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write_pidfile(server_config.pidfile);
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/* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
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bb_info_msg("%s (v"BB_VER") started", applet_name);
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option = find_option(server_config.options, DHCP_LEASE_TIME);
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server_config.max_lease_sec = LEASE_TIME;
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if (option) {
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move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
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server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
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}
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/* Sanity check */
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num_ips = server_config.end_ip - server_config.start_ip + 1;
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if (server_config.max_leases > num_ips) {
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bb_error_msg("max_leases=%u is too big, setting to %u",
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(unsigned)server_config.max_leases, num_ips);
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server_config.max_leases = num_ips;
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}
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g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0]));
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read_leases(server_config.lease_file);
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if (udhcp_read_interface(server_config.interface,
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&server_config.ifindex,
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&server_config.server_nip,
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server_config.server_mac)
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) {
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retval = 1;
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goto ret;
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}
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/* Setup the signal pipe */
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udhcp_sp_setup();
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timeout_end = monotonic_sec() + server_config.auto_time;
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while (1) { /* loop until universe collapses */
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int bytes;
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struct timeval tv;
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if (server_socket < 0) {
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server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
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server_config.interface);
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}
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max_sock = udhcp_sp_fd_set(&rfds, server_socket);
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if (server_config.auto_time) {
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tv.tv_sec = timeout_end - monotonic_sec();
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tv.tv_usec = 0;
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}
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retval = 0;
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if (!server_config.auto_time || tv.tv_sec > 0) {
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retval = select(max_sock + 1, &rfds, NULL, NULL,
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server_config.auto_time ? &tv : NULL);
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}
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if (retval == 0) {
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write_leases();
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timeout_end = monotonic_sec() + server_config.auto_time;
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continue;
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}
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if (retval < 0 && errno != EINTR) {
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log1("Error on select");
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continue;
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}
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switch (udhcp_sp_read(&rfds)) {
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case SIGUSR1:
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bb_info_msg("Received a SIGUSR1");
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write_leases();
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/* why not just reset the timeout, eh */
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timeout_end = monotonic_sec() + server_config.auto_time;
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continue;
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case SIGTERM:
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bb_info_msg("Received a SIGTERM");
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goto ret0;
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case 0: /* no signal: read a packet */
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break;
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default: /* signal or error (probably EINTR): back to select */
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continue;
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}
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bytes = udhcp_recv_kernel_packet(&packet, server_socket);
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if (bytes < 0) {
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/* bytes can also be -2 ("bad packet data") */
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if (bytes == -1 && errno != EINTR) {
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log1("Read error: %s, reopening socket", strerror(errno));
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close(server_socket);
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server_socket = -1;
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}
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continue;
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}
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if (packet.hlen != 6) {
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bb_error_msg("MAC length != 6, ignoring packet");
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continue;
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}
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state = get_option(&packet, DHCP_MESSAGE_TYPE);
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if (state == NULL) {
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bb_error_msg("no message type option, ignoring packet");
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continue;
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}
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/* Look for a static lease */
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static_lease_ip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
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if (static_lease_ip) {
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bb_info_msg("Found static lease: %x", static_lease_ip);
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memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
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fake_lease.lease_nip = static_lease_ip;
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fake_lease.expires = 0;
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lease = &fake_lease;
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} else {
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lease = find_lease_by_mac(packet.chaddr);
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}
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switch (state[0]) {
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case DHCPDISCOVER:
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log1("Received DISCOVER");
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if (send_offer(&packet) < 0) {
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bb_error_msg("send OFFER failed");
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}
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break;
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case DHCPREQUEST: {
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uint8_t *server_id_opt, *requested_opt;
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uint32_t server_id_net = server_id_net; /* for compiler */
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uint32_t requested_nip = requested_nip; /* for compiler */
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log1("Received REQUEST");
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requested_opt = get_option(&packet, DHCP_REQUESTED_IP);
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server_id_opt = get_option(&packet, DHCP_SERVER_ID);
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if (requested_opt)
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move_from_unaligned32(requested_nip, requested_opt);
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if (server_id_opt)
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move_from_unaligned32(server_id_net, server_id_opt);
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if (lease) {
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if (server_id_opt) {
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/* SELECTING State */
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if (server_id_net == server_config.server_nip
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&& requested_opt
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&& requested_nip == lease->lease_nip
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) {
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send_ACK(&packet, lease->lease_nip);
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}
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} else if (requested_opt) {
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/* INIT-REBOOT State */
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if (lease->lease_nip == requested_nip)
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send_ACK(&packet, lease->lease_nip);
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else
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send_NAK(&packet);
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} else if (lease->lease_nip == packet.ciaddr) {
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/* RENEWING or REBINDING State */
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send_ACK(&packet, lease->lease_nip);
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} else { /* don't know what to do!!!! */
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send_NAK(&packet);
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}
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/* what to do if we have no record of the client */
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} else if (server_id_opt) {
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/* SELECTING State */
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} else if (requested_opt) {
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/* INIT-REBOOT State */
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lease = find_lease_by_nip(requested_nip);
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if (lease) {
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if (is_expired_lease(lease)) {
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/* probably best if we drop this lease */
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memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
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} else {
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/* make some contention for this address */
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send_NAK(&packet);
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}
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} else {
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uint32_t r = ntohl(requested_nip);
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if (r < server_config.start_ip
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|| r > server_config.end_ip
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) {
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send_NAK(&packet);
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}
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/* else remain silent */
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}
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} else {
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/* RENEWING or REBINDING State */
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}
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break;
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}
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case DHCPDECLINE:
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log1("Received DECLINE");
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if (lease) {
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memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
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lease->expires = time(NULL) + server_config.decline_time;
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}
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break;
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case DHCPRELEASE:
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log1("Received RELEASE");
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if (lease)
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lease->expires = time(NULL);
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break;
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case DHCPINFORM:
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log1("Received INFORM");
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send_inform(&packet);
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break;
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default:
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bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
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}
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}
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ret0:
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retval = 0;
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ret:
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/*if (server_config.pidfile) - server_config.pidfile is never NULL */
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remove_pidfile(server_config.pidfile);
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return retval;
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}
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