Example #1
0
static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **clients,
		struct sockaddr_in *server_addr, uint32_t gw_ip)
{
	struct dhcpMessage dhcp_msg;
	fd_set rfds;
	size_t packlen;
	socklen_t addr_size;
	struct sockaddr_in client_addr;
	struct timeval tv;
	int i;

	while (!dhcprelay_stopflag) {
		FD_ZERO(&rfds);
		for (i = 0; i < num_sockets; i++)
			FD_SET(fds[i], &rfds);
		tv.tv_sec = SELECT_TIMEOUT;
		tv.tv_usec = 0;
		if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
			/* server */
			if (FD_ISSET(fds[0], &rfds)) {
				packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
				if (packlen > 0) {
					pass_back(&dhcp_msg, packlen, fds);
				}
			}
			for (i = 1; i < num_sockets; i++) {
				/* clients */
				if (!FD_ISSET(fds[i], &rfds))
					continue;
				addr_size = sizeof(struct sockaddr_in);
				packlen = recvfrom(fds[i], &dhcp_msg, sizeof(dhcp_msg), 0,
							(struct sockaddr *)(&client_addr), &addr_size);
				if (packlen <= 0)
					continue;
				if (read_interface(clients[i-1], NULL, &dhcp_msg.giaddr, NULL) < 0)
					dhcp_msg.giaddr = gw_ip;
				pass_on(&dhcp_msg, packlen, i, fds, &client_addr, server_addr);
			}
		}
		xid_expire();
	}
}
Example #2
0
int udhcpc_main(int argc, char *argv[])
{
	uint8_t *temp, *message;
	unsigned long t1 = 0, t2 = 0, xid = 0;
	unsigned long start = 0, lease;
	fd_set rfds;
	int retval;
	struct timeval tv;
	int c, len;
	struct dhcpMessage packet;
	struct in_addr temp_addr;
	long now;
	int max_fd;
	int sig;
	int no_clientid = 0;

	static const struct option arg_options[] = {
		{"clientid",	required_argument,	0, 'c'},
		{"clientid-none", no_argument,		0, 'C'},
		{"vendorclass",	required_argument,	0, 'V'},
		{"foreground",	no_argument,		0, 'f'},
		{"background",	no_argument,		0, 'b'},
		{"hostname",	required_argument,	0, 'H'},
		{"hostname",	required_argument,	0, 'h'},
		{"fqdn",	required_argument,	0, 'F'},
		{"interface",	required_argument,	0, 'i'},
		{"now",		no_argument,		0, 'n'},
		{"pidfile",	required_argument,	0, 'p'},
		{"quit",	no_argument,		0, 'q'},
		{"request",	required_argument,	0, 'r'},
		{"script",	required_argument,	0, 's'},
		{"timeout",	required_argument,	0, 'T'},
		{"version",	no_argument,		0, 'v'},
		{"retries",	required_argument,	0, 't'},
		{0, 0, 0, 0}
	};

	/* get options */
	while (1) {
		int option_index = 0;
		c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qr:s:T:t:v", arg_options, &option_index);
		if (c == -1) break;

		switch (c) {
		case 'c':
			if (no_clientid) bb_show_usage();
			len = strlen(optarg) > 255 ? 255 : strlen(optarg);
			free(client_config.clientid);
			client_config.clientid = xmalloc(len + 2);
			client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
			client_config.clientid[OPT_LEN] = len;
			client_config.clientid[OPT_DATA] = '\0';
			strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
			break;
		case 'C':
			if (client_config.clientid) bb_show_usage();
			no_clientid = 1;
			break;
		case 'V':
			len = strlen(optarg) > 255 ? 255 : strlen(optarg);
			free(client_config.vendorclass);
			client_config.vendorclass = xmalloc(len + 2);
			client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
			client_config.vendorclass[OPT_LEN] = len;
			strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
			break;
		case 'f':
			client_config.foreground = 1;
			break;
		case 'b':
			client_config.background_if_no_lease = 1;
			break;
		case 'h':
		case 'H':
			len = strlen(optarg) > 255 ? 255 : strlen(optarg);
			free(client_config.hostname);
			client_config.hostname = xmalloc(len + 2);
			client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
			client_config.hostname[OPT_LEN] = len;
			strncpy((char*)client_config.hostname + 2, optarg, len);
			break;
		case 'F':
			len = strlen(optarg) > 255 ? 255 : strlen(optarg);
			free(client_config.fqdn);
			client_config.fqdn = xmalloc(len + 5);
			client_config.fqdn[OPT_CODE] = DHCP_FQDN;
			client_config.fqdn[OPT_LEN] = len + 3;
			/* Flags: 0000NEOS
			S: 1 => Client requests Server to update A RR in DNS as well as PTR
			O: 1 => Server indicates to client that DNS has been updated regardless
			E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
			N: 1 => Client requests Server to not update DNS
			*/
			client_config.fqdn[OPT_LEN + 1] = 0x1;
			client_config.fqdn[OPT_LEN + 2] = 0;
			client_config.fqdn[OPT_LEN + 3] = 0;
			strncpy((char*)client_config.fqdn + 5, optarg, len);
			break;
		case 'i':
			client_config.interface =  optarg;
			break;
		case 'n':
			client_config.abort_if_no_lease = 1;
			break;
		case 'p':
			client_config.pidfile = optarg;
			break;
		case 'q':
			client_config.quit_after_lease = 1;
			break;
		case 'r':
			requested_ip = inet_addr(optarg);
			break;
		case 's':
			client_config.script = optarg;
			break;
		case 'T':
			client_config.timeout = atoi(optarg);
			break;
		case 't':
			client_config.retries = atoi(optarg);
			break;
		case 'v':
			printf("version %s\n\n", BB_VER);
			return 0;
			break;
		default:
			bb_show_usage();
		}
	}

	/* Start the log, sanitize fd's, and write a pid file */
	udhcp_start_log_and_pid("udhcpc", client_config.pidfile);

	if (read_interface(client_config.interface, &client_config.ifindex,
			   NULL, client_config.arp) < 0)
		return 1;

	/* if not set, and not suppressed, setup the default client ID */
	if (!client_config.clientid && !no_clientid) {
		client_config.clientid = xmalloc(6 + 3);
		client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
		client_config.clientid[OPT_LEN] = 7;
		client_config.clientid[OPT_DATA] = 1;
		memcpy(client_config.clientid + 3, client_config.arp, 6);
	}

	if (!client_config.vendorclass) {
		client_config.vendorclass = xmalloc(sizeof("udhcp "BB_VER) + 2);
		client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
		client_config.vendorclass[OPT_LEN] = sizeof("udhcp "BB_VER) - 1;
		client_config.vendorclass[OPT_DATA] = 1;
		memcpy(&client_config.vendorclass[OPT_DATA],
			"udhcp "BB_VER, sizeof("udhcp "BB_VER) - 1);
	}


	/* setup the signal pipe */
	udhcp_sp_setup();

	state = INIT_SELECTING;
	udhcp_run_script(NULL, "deconfig");
	change_mode(LISTEN_RAW);

	for (;;) {

		tv.tv_sec = timeout - uptime();
		tv.tv_usec = 0;

		if (listen_mode != LISTEN_NONE && fd < 0) {
			if (listen_mode == LISTEN_KERNEL)
				fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
			else
				fd = raw_socket(client_config.ifindex);
			if (fd < 0) {
				LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
				return 0;
			}
		}
		max_fd = udhcp_sp_fd_set(&rfds, fd);

		if (tv.tv_sec > 0) {
			DEBUG(LOG_INFO, "Waiting on select...");
			retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
		} else retval = 0; /* If we already timed out, fall through */

		now = uptime();
		if (retval == 0) {
			/* timeout dropped to zero */
			switch (state) {
			case INIT_SELECTING:
				if (packet_num < client_config.retries) {
					if (packet_num == 0)
						xid = random_xid();

					/* send discover packet */
					send_discover(xid, requested_ip); /* broadcast */

					timeout = now + client_config.timeout;
					packet_num++;
				} else {
					udhcp_run_script(NULL, "leasefail");
					if (client_config.background_if_no_lease) {
						LOG(LOG_INFO, "No lease, forking to background.");
						client_background();
					} else if (client_config.abort_if_no_lease) {
						LOG(LOG_INFO, "No lease, failing.");
						return 1;
					}
					/* wait to try again */
					packet_num = 0;
					timeout = now + 60;
				}
				break;
			case RENEW_REQUESTED:
			case REQUESTING:
				if (packet_num < client_config.retries) {
					/* send request packet */
					if (state == RENEW_REQUESTED)
						send_renew(xid, server_addr, requested_ip); /* unicast */
					else send_selecting(xid, server_addr, requested_ip); /* broadcast */

					timeout = now + ((packet_num == 2) ? 10 : 2);
					packet_num++;
				} else {
					/* timed out, go back to init state */
					if (state == RENEW_REQUESTED) udhcp_run_script(NULL, "deconfig");
					state = INIT_SELECTING;
					timeout = now;
					packet_num = 0;
					change_mode(LISTEN_RAW);
				}
				break;
			case BOUND:
				/* Lease is starting to run out, time to enter renewing state */
				state = RENEWING;
				change_mode(LISTEN_KERNEL);
				DEBUG(LOG_INFO, "Entering renew state");
				/* fall right through */
			case RENEWING:
				/* Either set a new T1, or enter REBINDING state */
				if ((t2 - t1) <= (lease / 14400 + 1)) {
					/* timed out, enter rebinding state */
					state = REBINDING;
					timeout = now + (t2 - t1);
					DEBUG(LOG_INFO, "Entering rebinding state");
				} else {
					/* send a request packet */
					send_renew(xid, server_addr, requested_ip); /* unicast */

					t1 = (t2 - t1) / 2 + t1;
					timeout = t1 + start;
				}
				break;
			case REBINDING:
				/* Either set a new T2, or enter INIT state */
				if ((lease - t2) <= (lease / 14400 + 1)) {
					/* timed out, enter init state */
					state = INIT_SELECTING;
					LOG(LOG_INFO, "Lease lost, entering init state");
					udhcp_run_script(NULL, "deconfig");
					timeout = now;
					packet_num = 0;
					change_mode(LISTEN_RAW);
				} else {
					/* send a request packet */
					send_renew(xid, 0, requested_ip); /* broadcast */

					t2 = (lease - t2) / 2 + t2;
					timeout = t2 + start;
				}
				break;
			case RELEASED:
				/* yah, I know, *you* say it would never happen */
				timeout = 0x7fffffff;
				break;
			}
		} else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
			/* a packet is ready, read it */

			if (listen_mode == LISTEN_KERNEL)
				len = udhcp_get_packet(&packet, fd);
			else len = get_raw_packet(&packet, fd);

			if (len == -1 && errno != EINTR) {
				DEBUG(LOG_INFO, "error on read, %m, reopening socket");
				change_mode(listen_mode); /* just close and reopen */
			}
			if (len < 0) continue;

			if (packet.xid != xid) {
				DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
					(unsigned long) packet.xid, xid);
				continue;
			}

			/* Ignore packets that aren't for us */
			if (memcmp(packet.chaddr, client_config.arp, 6)) {
				DEBUG(LOG_INFO, "packet does not have our chaddr -- ignoring");
				continue;
			}

			if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
				DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
				continue;
			}

			switch (state) {
			case INIT_SELECTING:
				/* Must be a DHCPOFFER to one of our xid's */
				if (*message == DHCPOFFER) {
					if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
						memcpy(&server_addr, temp, 4);
						xid = packet.xid;
						requested_ip = packet.yiaddr;

						/* enter requesting state */
						state = REQUESTING;
						timeout = now;
						packet_num = 0;
					} else {
						DEBUG(LOG_ERR, "No server ID in message");
					}
				}
				break;
			case RENEW_REQUESTED:
			case REQUESTING:
			case RENEWING:
			case REBINDING:
				if (*message == DHCPACK) {
					if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
						LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
						lease = 60 * 60;
					} else {
						memcpy(&lease, temp, 4);
						lease = ntohl(lease);
					}

					/* enter bound state */
					t1 = lease / 2;

					/* little fixed point for n * .875 */
					t2 = (lease * 0x7) >> 3;
					temp_addr.s_addr = packet.yiaddr;
					LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
						inet_ntoa(temp_addr), lease);
					start = now;
					timeout = t1 + start;
					requested_ip = packet.yiaddr;
					udhcp_run_script(&packet,
						   ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));

					state = BOUND;
					change_mode(LISTEN_NONE);
					if (client_config.quit_after_lease)
						return 0;
					if (!client_config.foreground)
						client_background();

				} else if (*message == DHCPNAK) {
					/* return to init state */
					LOG(LOG_INFO, "Received DHCP NAK");
					udhcp_run_script(&packet, "nak");
					if (state != REQUESTING)
						udhcp_run_script(NULL, "deconfig");
					state = INIT_SELECTING;
					timeout = now;
					requested_ip = 0;
					packet_num = 0;
					change_mode(LISTEN_RAW);
					sleep(3); /* avoid excessive network traffic */
				}
				break;
			/* case BOUND, RELEASED: - ignore all packets */
			}
		} else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
Example #3
0
int udhcpc_main(int argc, char **argv)
{
	uint8_t *temp, *message;
	char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_t;
	unsigned long t1 = 0, t2 = 0, xid = 0;
	unsigned long start = 0, lease = 0;
	long now;
	unsigned opt;
	int max_fd;
	int sig;
	int retval;
	int len;
	int no_clientid = 0;
	fd_set rfds;
	struct timeval tv;
	struct dhcpMessage packet;
	struct in_addr temp_addr;

	enum {
		OPT_c = 1 << 0,
		OPT_C = 1 << 1,
		OPT_V = 1 << 2,
		OPT_f = 1 << 3,
		OPT_b = 1 << 4,
		OPT_H = 1 << 5,
		OPT_h = 1 << 6,
		OPT_F = 1 << 7,
		OPT_i = 1 << 8,
		OPT_n = 1 << 9,
		OPT_p = 1 << 10,
		OPT_q = 1 << 11,
		OPT_R = 1 << 12,
		OPT_r = 1 << 13,
		OPT_s = 1 << 14,
		OPT_T = 1 << 15,
		OPT_t = 1 << 16,
		OPT_v = 1 << 17,
	};
#if ENABLE_GETOPT_LONG
	static const struct option arg_options[] = {
		{ "clientid",   required_argument,      0, 'c' },
		{ "clientid-none", no_argument,         0, 'C' },
		{ "vendorclass", required_argument,     0, 'V' },
		{ "foreground", no_argument,            0, 'f' },
		{ "background", no_argument,            0, 'b' },
		{ "hostname",   required_argument,      0, 'H' },
		{ "hostname",   required_argument,      0, 'h' },
		{ "fqdn",       required_argument,      0, 'F' },
		{ "interface",  required_argument,      0, 'i' },
		{ "now",        no_argument,            0, 'n' },
		{ "pidfile",    required_argument,      0, 'p' },
		{ "quit",       no_argument,            0, 'q' },
		{ "release",    no_argument,            0, 'R' },
		{ "request",    required_argument,      0, 'r' },
		{ "script",     required_argument,      0, 's' },
		{ "timeout",    required_argument,      0, 'T' },
		{ "version",    no_argument,            0, 'v' },
		{ "retries",    required_argument,      0, 't' },
		{ 0, 0, 0, 0 }
	};
#endif
	/* Default options. */
	client_config.interface = "eth0";
	client_config.script = DEFAULT_SCRIPT;
	client_config.retries = 3;
	client_config.timeout = 3;

	/* Parse command line */
	opt_complementary = "?:c--C:C--c" // mutually exclusive
	                    ":hH:Hh"; // -h and -H are the same
#if ENABLE_GETOPT_LONG
	applet_long_options = arg_options;
#endif
	opt = getopt32(argc, argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:v",
		&str_c, &str_V, &str_h, &str_h, &str_F,
		&client_config.interface, &client_config.pidfile, &str_r,
		&client_config.script, &str_T, &str_t
		);

	if (opt & OPT_c)
		client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
	if (opt & OPT_C)
		no_clientid = 1;
	if (opt & OPT_V)
		client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
	if (opt & OPT_f)
		client_config.foreground = 1;
	if (opt & OPT_b)
		client_config.background_if_no_lease = 1;
	if (opt & OPT_h)
		client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
	if (opt & OPT_F) {
		client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
		/* Flags: 0000NEOS
		S: 1 => Client requests Server to update A RR in DNS as well as PTR
		O: 1 => Server indicates to client that DNS has been updated regardless
		E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
		N: 1 => Client requests Server to not update DNS
		*/
		client_config.fqdn[OPT_DATA + 0] = 0x1;
		/* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
		/* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
	}
	// if (opt & OPT_i) client_config.interface = ...
	if (opt & OPT_n)
		client_config.abort_if_no_lease = 1;
	// if (opt & OPT_p) client_config.pidfile = ...
	if (opt & OPT_q)
		client_config.quit_after_lease = 1;
	if (opt & OPT_R)
		client_config.release_on_quit = 1;
	if (opt & OPT_r)
		requested_ip = inet_addr(str_r);
	// if (opt & OPT_s) client_config.script = ...
	if (opt & OPT_T)
		client_config.timeout = xatoi_u(str_T);
	if (opt & OPT_t)
		client_config.retries = xatoi_u(str_t);
	if (opt & OPT_v) {
		printf("version %s\n\n", BB_VER);
		return 0;
	}

	if (ENABLE_FEATURE_UDHCP_SYSLOG) {
		openlog(applet_name, LOG_PID, LOG_LOCAL0);
		logmode |= LOGMODE_SYSLOG;
	}

	if (read_interface(client_config.interface, &client_config.ifindex,
			   NULL, client_config.arp) < 0)
		return 1;

	/* Sanitize fd's and write pidfile */
	udhcp_make_pidfile(client_config.pidfile);

	/* if not set, and not suppressed, setup the default client ID */
	if (!client_config.clientid && !no_clientid) {
		client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
		client_config.clientid[OPT_DATA] = 1;
		memcpy(client_config.clientid + OPT_DATA+1, client_config.arp, 6);
	}

	if (!client_config.vendorclass)
		client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, "udhcp "BB_VER, 0);

	/* setup the signal pipe */
	udhcp_sp_setup();

	state = INIT_SELECTING;
	udhcp_run_script(NULL, "deconfig");
	change_mode(LISTEN_RAW);

	for (;;) {
		tv.tv_sec = timeout - uptime();
		tv.tv_usec = 0;

		if (listen_mode != LISTEN_NONE && sockfd < 0) {
			if (listen_mode == LISTEN_KERNEL)
				sockfd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
			else
				sockfd = raw_socket(client_config.ifindex);
		}
		max_fd = udhcp_sp_fd_set(&rfds, sockfd);

		if (tv.tv_sec > 0) {
			DEBUG("Waiting on select...");
			retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
		} else retval = 0; /* If we already timed out, fall through */

		now = uptime();
		if (retval == 0) {
			/* timeout dropped to zero */
			switch (state) {
			case INIT_SELECTING:
				if (packet_num < client_config.retries) {
					if (packet_num == 0)
						xid = random_xid();

					/* send discover packet */
					send_discover(xid, requested_ip); /* broadcast */

					timeout = now + client_config.timeout;
					packet_num++;
				} else {
					udhcp_run_script(NULL, "leasefail");
					if (client_config.background_if_no_lease) {
						bb_info_msg("No lease, forking to background");
						client_background();
					} else if (client_config.abort_if_no_lease) {
						bb_info_msg("No lease, failing");
						retval = 1;
						goto ret;
					}
					/* wait to try again */
					packet_num = 0;
					timeout = now + 60;
				}
				break;
			case RENEW_REQUESTED:
			case REQUESTING:
				if (packet_num < client_config.retries) {
					/* send request packet */
					if (state == RENEW_REQUESTED)
						send_renew(xid, server_addr, requested_ip); /* unicast */
					else send_selecting(xid, server_addr, requested_ip); /* broadcast */

					timeout = now + ((packet_num == 2) ? 10 : 2);
					packet_num++;
				} else {
					/* timed out, go back to init state */
					if (state == RENEW_REQUESTED)
						udhcp_run_script(NULL, "deconfig");
					state = INIT_SELECTING;
					timeout = now;
					packet_num = 0;
					change_mode(LISTEN_RAW);
				}
				break;
			case BOUND:
				/* Lease is starting to run out, time to enter renewing state */
				state = RENEWING;
				change_mode(LISTEN_KERNEL);
				DEBUG("Entering renew state");
				/* fall right through */
			case RENEWING:
				/* Either set a new T1, or enter REBINDING state */
				if ((t2 - t1) <= (lease / 14400 + 1)) {
					/* timed out, enter rebinding state */
					state = REBINDING;
					timeout = now + (t2 - t1);
					DEBUG("Entering rebinding state");
				} else {
					/* send a request packet */
					send_renew(xid, server_addr, requested_ip); /* unicast */

					t1 = (t2 - t1) / 2 + t1;
					timeout = t1 + start;
				}
				break;
			case REBINDING:
				/* Either set a new T2, or enter INIT state */
				if ((lease - t2) <= (lease / 14400 + 1)) {
					/* timed out, enter init state */
					state = INIT_SELECTING;
					bb_info_msg("Lease lost, entering init state");
					udhcp_run_script(NULL, "deconfig");
					timeout = now;
					packet_num = 0;
					change_mode(LISTEN_RAW);
				} else {
					/* send a request packet */
					send_renew(xid, 0, requested_ip); /* broadcast */

					t2 = (lease - t2) / 2 + t2;
					timeout = t2 + start;
				}
				break;
			case RELEASED:
				/* yah, I know, *you* say it would never happen */
				timeout = 0x7fffffff;
				break;
			}
		} else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
			/* a packet is ready, read it */

			if (listen_mode == LISTEN_KERNEL)
				len = udhcp_get_packet(&packet, sockfd);
			else len = get_raw_packet(&packet, sockfd);

			if (len == -1 && errno != EINTR) {
				DEBUG("error on read, %s, reopening socket", strerror(errno));
				change_mode(listen_mode); /* just close and reopen */
			}
			if (len < 0) continue;

			if (packet.xid != xid) {
				DEBUG("Ignoring XID %lx (our xid is %lx)",
					(unsigned long) packet.xid, xid);
				continue;
			}

			/* Ignore packets that aren't for us */
			if (memcmp(packet.chaddr, client_config.arp, 6)) {
				DEBUG("Packet does not have our chaddr - ignoring");
				continue;
			}

			message = get_option(&packet, DHCP_MESSAGE_TYPE);
			if (message == NULL) {
				bb_error_msg("cannot get option from packet - ignoring");
				continue;
			}

			switch (state) {
			case INIT_SELECTING:
				/* Must be a DHCPOFFER to one of our xid's */
				if (*message == DHCPOFFER) {
					temp = get_option(&packet, DHCP_SERVER_ID);
					if (temp) {
						/* can be misaligned, thus memcpy */
						memcpy(&server_addr, temp, 4);
						xid = packet.xid;
						requested_ip = packet.yiaddr;

						/* enter requesting state */
						state = REQUESTING;
						timeout = now;
						packet_num = 0;
					} else {
						bb_error_msg("no server ID in message");
					}
				}
				break;
			case RENEW_REQUESTED:
			case REQUESTING:
			case RENEWING:
			case REBINDING:
				if (*message == DHCPACK) {
					temp = get_option(&packet, DHCP_LEASE_TIME);
					if (!temp) {
						bb_error_msg("no lease time with ACK, using 1 hour lease");
						lease = 60 * 60;
					} else {
						/* can be misaligned, thus memcpy */
						memcpy(&lease, temp, 4);
						lease = ntohl(lease);
					}

					/* enter bound state */
					t1 = lease / 2;

					/* little fixed point for n * .875 */
					t2 = (lease * 0x7) >> 3;
					temp_addr.s_addr = packet.yiaddr;
					bb_info_msg("Lease of %s obtained, lease time %ld",
						inet_ntoa(temp_addr), lease);
					start = now;
					timeout = t1 + start;
					requested_ip = packet.yiaddr;
					udhcp_run_script(&packet,
						   ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));

					state = BOUND;
					change_mode(LISTEN_NONE);
					if (client_config.quit_after_lease) {
						if (client_config.release_on_quit)
							perform_release();
						goto ret0;
					}
					if (!client_config.foreground)
						client_background();

				} else if (*message == DHCPNAK) {
					/* return to init state */
					bb_info_msg("Received DHCP NAK");
					udhcp_run_script(&packet, "nak");
					if (state != REQUESTING)
						udhcp_run_script(NULL, "deconfig");
					state = INIT_SELECTING;
					timeout = now;
					requested_ip = 0;
					packet_num = 0;
					change_mode(LISTEN_RAW);
					sleep(3); /* avoid excessive network traffic */
				}
				break;
			/* case BOUND, RELEASED: - ignore all packets */
			}
		} else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {