xref: /freebsd-13-stable/sbin/dhclient/dhclient.c (revision c8c624de57b072d14c1ab23167880a069ef51f11)

/*	$OpenBSD: dhclient.c,v 1.63 2005/02/06 17:10:13 krw Exp $	*/

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright 2004 Henning Brauer <henning@openbsd.org>
 * Copyright (c) 1995, 1996, 1997, 1998, 1999
 * The Internet Software Consortium.    All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of The Internet Software Consortium nor the names
 *    of its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This software has been written for the Internet Software Consortium
 * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
 * Enterprises.  To learn more about the Internet Software Consortium,
 * see ``http://www.vix.com/isc''.  To learn more about Vixie
 * Enterprises, see ``http://www.vix.com''.
 *
 * This client was substantially modified and enhanced by Elliot Poger
 * for use on Linux while he was working on the MosquitoNet project at
 * Stanford.
 *
 * The current version owes much to Elliot's Linux enhancements, but
 * was substantially reorganized and partially rewritten by Ted Lemon
 * so as to use the same networking framework that the Internet Software
 * Consortium DHCP server uses.   Much system-specific configuration code
 * was moved into a shell script so that as support for more operating
 * systems is added, it will not be necessary to port and maintain
 * system-specific configuration code to these operating systems - instead,
 * the shell script can invoke the native tools to accomplish the same
 * purpose.
 */

#include <sys/cdefs.h>
#include "dhcpd.h"
#include "privsep.h"

#include <sys/capsicum.h>
#include <sys/endian.h>

#include <capsicum_helpers.h>
#include <libgen.h>

#include <net80211/ieee80211_freebsd.h>


#ifndef _PATH_VAREMPTY
#define	_PATH_VAREMPTY	"/var/empty"
#endif

#define	PERIOD 0x2e
#define	hyphenchar(c) ((c) == 0x2d)
#define	bslashchar(c) ((c) == 0x5c)
#define	periodchar(c) ((c) == PERIOD)
#define	asterchar(c) ((c) == 0x2a)
#define	alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) || \
	    ((c) >= 0x61 && (c) <= 0x7a))
#define	digitchar(c) ((c) >= 0x30 && (c) <= 0x39)
#define	whitechar(c) ((c) == ' ' || (c) == '\t')

#define	borderchar(c) (alphachar(c) || digitchar(c))
#define	middlechar(c) (borderchar(c) || hyphenchar(c))
#define	domainchar(c) ((c) > 0x20 && (c) < 0x7f)

#define	CLIENT_PATH "PATH=/usr/bin:/usr/sbin:/bin:/sbin"

cap_channel_t *capsyslog;

time_t cur_time;	/* Seconds since epoch. */
struct timespec time_now;	/* CLOCK_MONOTONIC. */
static time_t default_lease_time = 43200; /* 12 hours... */

const char *path_dhclient_conf = _PATH_DHCLIENT_CONF;
char *path_dhclient_db = NULL;

int log_perror = 1;
static int privfd;
static int nullfd = -1;

static char hostname[_POSIX_HOST_NAME_MAX + 1];

static struct iaddr iaddr_broadcast = { 4, { 255, 255, 255, 255 } };
static struct in_addr inaddr_any, inaddr_broadcast;

static char *path_dhclient_pidfile;
struct pidfh *pidfile;

/*
 * ASSERT_STATE() does nothing now; it used to be
 * assert (state_is == state_shouldbe).
 */
#define ASSERT_STATE(state_is, state_shouldbe) {}

/*
 * We need to check that the expiry, renewal and rebind times are not beyond
 * the end of time (~2038 when a 32-bit time_t is being used).
 */
#define TIME_MAX        ((((time_t) 1 << (sizeof(time_t) * CHAR_BIT - 2)) - 1) * 2 + 1)

static struct timespec arp_timeout = { .tv_sec = 0, .tv_nsec = 250 * 1000 * 1000 };
static const struct timespec zero_timespec = { .tv_sec = 0, .tv_nsec = 0 };
int		log_priority;
static int		no_daemon;
static int		unknown_ok = 1;
static int		routefd;

struct interface_info	*ifi;

int		 findproto(char *, int);
struct sockaddr	*get_ifa(char *, int);
void		 routehandler(struct protocol *);
void		 usage(void);
int		 check_option(struct client_lease *l, int option);
int		 check_classless_option(unsigned char *data, int len);
int		 ipv4addrs(const char * buf);
int		 res_hnok(const char *dn);
int		 check_search(const char *srch);
const char	*option_as_string(unsigned int code, unsigned char *data, int len);
int		 fork_privchld(int, int);

#define	ROUNDUP(a) \
	    ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
#define	ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))

/* Minimum MTU is 68 as per RFC791, p. 24 */
#define MIN_MTU 68

static time_t	scripttime;

int
findproto(char *cp, int n)
{
	struct sockaddr *sa;
	unsigned i;

	if (n == 0)
		return -1;
	for (i = 1; i; i <<= 1) {
		if (i & n) {
			sa = (struct sockaddr *)cp;
			switch (i) {
			case RTA_IFA:
			case RTA_DST:
			case RTA_GATEWAY:
			case RTA_NETMASK:
				if (sa->sa_family == AF_INET)
					return AF_INET;
				if (sa->sa_family == AF_INET6)
					return AF_INET6;
				break;
			case RTA_IFP:
				break;
			}
			ADVANCE(cp, sa);
		}
	}
	return (-1);
}

struct sockaddr *
get_ifa(char *cp, int n)
{
	struct sockaddr *sa;
	unsigned i;

	if (n == 0)
		return (NULL);
	for (i = 1; i; i <<= 1)
		if (i & n) {
			sa = (struct sockaddr *)cp;
			if (i == RTA_IFA)
				return (sa);
			ADVANCE(cp, sa);
		}

	return (NULL);
}

static struct iaddr defaddr = { .len = 4 };
static uint8_t curbssid[6];

static void
disassoc(void *arg)
{
	struct interface_info *_ifi = arg;

	/*
	 * Clear existing state.
	 */
	if (_ifi->client->active != NULL) {
		script_init("EXPIRE", NULL);
		script_write_params("old_",
		    _ifi->client->active);
		if (_ifi->client->alias)
			script_write_params("alias_",
				_ifi->client->alias);
		script_go();
	}
	_ifi->client->state = S_INIT;
}

void
routehandler(struct protocol *p __unused)
{
	char msg[2048], *addr;
	struct rt_msghdr *rtm;
	struct if_msghdr *ifm;
	struct ifa_msghdr *ifam;
	struct if_announcemsghdr *ifan;
	struct ieee80211_join_event *jev;
	struct client_lease *l;
	time_t t = time(NULL);
	struct sockaddr_in *sa;
	struct iaddr a;
	ssize_t n;
	int linkstat;

	n = read(routefd, &msg, sizeof(msg));
	rtm = (struct rt_msghdr *)msg;
	if (n < (ssize_t)sizeof(rtm->rtm_msglen) ||
	    n < (ssize_t)rtm->rtm_msglen ||
	    rtm->rtm_version != RTM_VERSION)
		return;

	switch (rtm->rtm_type) {
	case RTM_NEWADDR:
	case RTM_DELADDR:
		ifam = (struct ifa_msghdr *)rtm;

		if (ifam->ifam_index != ifi->index)
			break;
		if (findproto((char *)(ifam + 1), ifam->ifam_addrs) != AF_INET)
			break;
		if (scripttime == 0 || t < scripttime + 10)
			break;

		sa = (struct sockaddr_in*)get_ifa((char *)(ifam + 1), ifam->ifam_addrs);
		if (sa == NULL)
			break;

		if ((a.len = sizeof(struct in_addr)) > sizeof(a.iabuf))
			error("king bula sez: len mismatch");
		memcpy(a.iabuf, &sa->sin_addr, a.len);
		if (addr_eq(a, defaddr))
			break;

		for (l = ifi->client->active; l != NULL; l = l->next)
			if (addr_eq(a, l->address))
				break;

		if (l == NULL)	/* added/deleted addr is not the one we set */
			break;

		addr = inet_ntoa(sa->sin_addr);
		if (rtm->rtm_type == RTM_NEWADDR)  {
			/*
			 * XXX: If someone other than us adds our address,
			 * should we assume they are taking over from us,
			 * delete the lease record, and exit without modifying
			 * the interface?
			 */
			warning("My address (%s) was re-added", addr);
		} else {
			warning("My address (%s) was deleted, dhclient exiting",
			    addr);
			goto die;
		}
		break;
	case RTM_IFINFO:
		ifm = (struct if_msghdr *)rtm;
		if (ifm->ifm_index != ifi->index)
			break;
		if ((rtm->rtm_flags & RTF_UP) == 0) {
			warning("Interface %s is down, dhclient exiting",
			    ifi->name);
			goto die;
		}
		linkstat = interface_link_status(ifi->name);
		if (linkstat != ifi->linkstat) {
			debug("%s link state %s -> %s", ifi->name,
			    ifi->linkstat ? "up" : "down",
			    linkstat ? "up" : "down");
			ifi->linkstat = linkstat;
			if (linkstat)
				state_reboot(ifi);
		}
		break;
	case RTM_IFANNOUNCE:
		ifan = (struct if_announcemsghdr *)rtm;
		if (ifan->ifan_what == IFAN_DEPARTURE &&
		    ifan->ifan_index == ifi->index) {
			warning("Interface %s is gone, dhclient exiting",
			    ifi->name);
			goto die;
		}
		break;
	case RTM_IEEE80211:
		ifan = (struct if_announcemsghdr *)rtm;
		if (ifan->ifan_index != ifi->index)
			break;
		switch (ifan->ifan_what) {
		case RTM_IEEE80211_ASSOC:
		case RTM_IEEE80211_REASSOC:
			/*
			 * Use assoc/reassoc event to kick state machine
			 * in case we roam.  Otherwise fall back to the
			 * normal state machine just like a wired network.
			 */
			jev = (struct ieee80211_join_event *) &ifan[1];
			if (memcmp(curbssid, jev->iev_addr, 6)) {
				disassoc(ifi);
				state_reboot(ifi);
			}
			memcpy(curbssid, jev->iev_addr, 6);
			break;
		}
		break;
	default:
		break;
	}
	return;

die:
	script_init("FAIL", NULL);
	if (ifi->client->alias)
		script_write_params("alias_", ifi->client->alias);
	script_go();
	if (pidfile != NULL)
		pidfile_remove(pidfile);
	exit(1);
}

static void
init_casper(void)
{
	cap_channel_t		*casper;

	casper = cap_init();
	if (casper == NULL)
		error("unable to start casper");

	capsyslog = cap_service_open(casper, "system.syslog");
	cap_close(casper);
	if (capsyslog == NULL)
		error("unable to open system.syslog service");
}

int
main(int argc, char *argv[])
{
	u_int			 capmode;
	int			 ch, fd, quiet = 0, i = 0;
	int			 pipe_fd[2];
	int			 immediate_daemon = 0;
	struct passwd		*pw;
	pid_t			 otherpid;
	cap_rights_t		 rights;

	init_casper();

	/* Initially, log errors to stderr as well as to syslogd. */
	cap_openlog(capsyslog, getprogname(), LOG_PID | LOG_NDELAY, DHCPD_LOG_FACILITY);
	cap_setlogmask(capsyslog, LOG_UPTO(LOG_DEBUG));

	while ((ch = getopt(argc, argv, "bc:dl:np:qu")) != -1)
		switch (ch) {
		case 'b':
			immediate_daemon = 1;
			break;
		case 'c':
			path_dhclient_conf = optarg;
			break;
		case 'd':
			no_daemon = 1;
			break;
		case 'l':
			path_dhclient_db = optarg;
			break;
		case 'n':
			arp_timeout = zero_timespec;
			break;
		case 'p':
			path_dhclient_pidfile = optarg;
			break;
		case 'q':
			quiet = 1;
			break;
		case 'u':
			unknown_ok = 0;
			break;
		default:
			usage();
		}

	argc -= optind;
	argv += optind;

	if (argc != 1)
		usage();

	if (path_dhclient_pidfile == NULL) {
		asprintf(&path_dhclient_pidfile,
		    "%s/dhclient/dhclient.%s.pid", _PATH_VARRUN, *argv);
		if (path_dhclient_pidfile == NULL)
			error("asprintf");
	}
	pidfile = pidfile_open(path_dhclient_pidfile, 0644, &otherpid);
	if (pidfile == NULL) {
		if (errno == EEXIST)
			error("dhclient already running, pid: %d.", otherpid);
		if (errno == EAGAIN)
			error("dhclient already running.");
		warning("Cannot open or create pidfile: %m");
	}

	if ((ifi = calloc(1, sizeof(struct interface_info))) == NULL)
		error("calloc");
	if (strlcpy(ifi->name, argv[0], IFNAMSIZ) >= IFNAMSIZ)
		error("Interface name too long");
	if (path_dhclient_db == NULL && asprintf(&path_dhclient_db, "%s.%s",
	    _PATH_DHCLIENT_DB, ifi->name) == -1)
		error("asprintf");

	if (quiet)
		log_perror = 0;

	tzset();
	clock_gettime(CLOCK_MONOTONIC, &time_now);
	cur_time = time(NULL);

	inaddr_broadcast.s_addr = INADDR_BROADCAST;
	inaddr_any.s_addr = INADDR_ANY;

	read_client_conf();

	/* The next bit is potentially very time-consuming, so write out
	   the pidfile right away.  We will write it out again with the
	   correct pid after daemonizing. */
	if (pidfile != NULL)
		pidfile_write(pidfile);

	if (!interface_link_status(ifi->name)) {
		fprintf(stderr, "%s: no link ...", ifi->name);
		fflush(stderr);
		sleep(1);
		while (!interface_link_status(ifi->name)) {
			fprintf(stderr, ".");
			fflush(stderr);
			if (++i > 10) {
				fprintf(stderr, " giving up\n");
				exit(1);
			}
			sleep(1);
		}
		fprintf(stderr, " got link\n");
	}
	ifi->linkstat = 1;

	if ((nullfd = open(_PATH_DEVNULL, O_RDWR, 0)) == -1)
		error("cannot open %s: %m", _PATH_DEVNULL);

	if ((pw = getpwnam("_dhcp")) == NULL) {
		warning("no such user: _dhcp, falling back to \"nobody\"");
		if ((pw = getpwnam("nobody")) == NULL)
			error("no such user: nobody");
	}

	/*
	 * Obtain hostname before entering capability mode - it won't be
	 * possible then, as reading kern.hostname is not permitted.
	 */
	if (gethostname(hostname, sizeof(hostname)) < 0)
		hostname[0] = '\0';

	priv_script_init("PREINIT", NULL);
	if (ifi->client->alias)
		priv_script_write_params("alias_", ifi->client->alias);
	priv_script_go();

	/* set up the interface */
	discover_interfaces(ifi);

	if (pipe(pipe_fd) == -1)
		error("pipe");

	fork_privchld(pipe_fd[0], pipe_fd[1]);

	close(ifi->ufdesc);
	ifi->ufdesc = -1;
	close(ifi->wfdesc);
	ifi->wfdesc = -1;

	close(pipe_fd[0]);
	privfd = pipe_fd[1];
	cap_rights_init(&rights, CAP_READ, CAP_WRITE);
	if (caph_rights_limit(privfd, &rights) < 0)
		error("can't limit private descriptor: %m");

	if ((fd = open(path_dhclient_db, O_RDONLY|O_EXLOCK|O_CREAT, 0)) == -1)
		error("can't open and lock %s: %m", path_dhclient_db);
	read_client_leases();
	rewrite_client_leases();
	close(fd);

	if ((routefd = socket(PF_ROUTE, SOCK_RAW, 0)) != -1)
		add_protocol("AF_ROUTE", routefd, routehandler, ifi);
	if (shutdown(routefd, SHUT_WR) < 0)
		error("can't shutdown route socket: %m");
	cap_rights_init(&rights, CAP_EVENT, CAP_READ);
	if (caph_rights_limit(routefd, &rights) < 0)
		error("can't limit route socket: %m");

	endpwent();

	setproctitle("%s", ifi->name);

	/* setgroups(2) is not permitted in capability mode. */
	if (setgroups(1, &pw->pw_gid) != 0)
		error("can't restrict groups: %m");

	if (caph_enter_casper() < 0)
		error("can't enter capability mode: %m");

	/*
	 * If we are not in capability mode (i.e., Capsicum or libcasper is
	 * disabled), try to restrict filesystem access.  This will fail if
	 * kern.chroot_allow_open_directories is 0 or the process is jailed.
	 */
	if (cap_getmode(&capmode) < 0 || capmode == 0) {
		if (chroot(_PATH_VAREMPTY) == -1)
			error("chroot");
		if (chdir("/") == -1)
			error("chdir(\"/\")");
	}

	if (setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
		error("can't drop privileges: %m");

	if (immediate_daemon)
		go_daemon();

	ifi->client->state = S_INIT;
	state_reboot(ifi);

	bootp_packet_handler = do_packet;

	dispatch();

	/* not reached */
	return (0);
}

void
usage(void)
{

	fprintf(stderr, "usage: %s [-bdnqu] ", getprogname());
	fprintf(stderr, "[-c conffile] [-l leasefile] interface\n");
	exit(1);
}

/*
 * Individual States:
 *
 * Each routine is called from the dhclient_state_machine() in one of
 * these conditions:
 * -> entering INIT state
 * -> recvpacket_flag == 0: timeout in this state
 * -> otherwise: received a packet in this state
 *
 * Return conditions as handled by dhclient_state_machine():
 * Returns 1, sendpacket_flag = 1: send packet, reset timer.
 * Returns 1, sendpacket_flag = 0: just reset the timer (wait for a milestone).
 * Returns 0: finish the nap which was interrupted for no good reason.
 *
 * Several per-interface variables are used to keep track of the process:
 *   active_lease: the lease that is being used on the interface
 *                 (null pointer if not configured yet).
 *   offered_leases: leases corresponding to DHCPOFFER messages that have
 *                   been sent to us by DHCP servers.
 *   acked_leases: leases corresponding to DHCPACK messages that have been
 *                 sent to us by DHCP servers.
 *   sendpacket: DHCP packet we're trying to send.
 *   destination: IP address to send sendpacket to
 * In addition, there are several relevant per-lease variables.
 *   T1_expiry, T2_expiry, lease_expiry: lease milestones
 * In the active lease, these control the process of renewing the lease;
 * In leases on the acked_leases list, this simply determines when we
 * can no longer legitimately use the lease.
 */

void
state_reboot(void *ipp)
{
	struct interface_info *ip = ipp;

	/* If we don't remember an active lease, go straight to INIT. */
	if (!ip->client->active || ip->client->active->is_bootp) {
		state_init(ip);
		return;
	}

	/* We are in the rebooting state. */
	ip->client->state = S_REBOOTING;

	/* make_request doesn't initialize xid because it normally comes
	   from the DHCPDISCOVER, but we haven't sent a DHCPDISCOVER,
	   so pick an xid now. */
	ip->client->xid = arc4random();

	/* Make a DHCPREQUEST packet, and set appropriate per-interface
	   flags. */
	make_request(ip, ip->client->active);
	ip->client->destination = iaddr_broadcast;
	ip->client->first_sending = cur_time;
	ip->client->interval = ip->client->config->initial_interval;

	/* Zap the medium list... */
	ip->client->medium = NULL;

	/* Send out the first DHCPREQUEST packet. */
	send_request(ip);
}

/*
 * Called when a lease has completely expired and we've
 * been unable to renew it.
 */
void
state_init(void *ipp)
{
	struct interface_info *ip = ipp;

	ASSERT_STATE(state, S_INIT);

	/* Make a DHCPDISCOVER packet, and set appropriate per-interface
	   flags. */
	make_discover(ip, ip->client->active);
	ip->client->xid = ip->client->packet.xid;
	ip->client->destination = iaddr_broadcast;
	ip->client->state = S_SELECTING;
	ip->client->first_sending = cur_time;
	ip->client->interval = ip->client->config->initial_interval;

	/* Add an immediate timeout to cause the first DHCPDISCOVER packet
	   to go out. */
	send_discover(ip);
}

/*
 * state_selecting is called when one or more DHCPOFFER packets
 * have been received and a configurable period of time has passed.
 */
void
state_selecting(void *ipp)
{
	struct interface_info *ip = ipp;
	struct client_lease *lp, *next, *picked;

	ASSERT_STATE(state, S_SELECTING);

	/* Cancel state_selecting and send_discover timeouts, since either
	   one could have got us here. */
	cancel_timeout(state_selecting, ip);
	cancel_timeout(send_discover, ip);

	/* We have received one or more DHCPOFFER packets.   Currently,
	   the only criterion by which we judge leases is whether or
	   not we get a response when we arp for them. */
	picked = NULL;
	for (lp = ip->client->offered_leases; lp; lp = next) {
		next = lp->next;

		/* Check to see if we got an ARPREPLY for the address
		   in this particular lease. */
		if (!picked) {
			script_init("ARPCHECK", lp->medium);
			script_write_params("check_", lp);

			/* If the ARPCHECK code detects another
			   machine using the offered address, it exits
			   nonzero.  We need to send a DHCPDECLINE and
			   toss the lease. */
			if (script_go()) {
				make_decline(ip, lp);
				send_decline(ip);
				goto freeit;
			}
			picked = lp;
			picked->next = NULL;
		} else {
freeit:
			free_client_lease(lp);
		}
	}
	ip->client->offered_leases = NULL;

	/* If we just tossed all the leases we were offered, go back
	   to square one. */
	if (!picked) {
		ip->client->state = S_INIT;
		state_init(ip);
		return;
	}

	/* If it was a BOOTREPLY, we can just take the address right now. */
	if (!picked->options[DHO_DHCP_MESSAGE_TYPE].len) {
		ip->client->new = picked;

		/* Make up some lease expiry times
		   XXX these should be configurable. */
		ip->client->new->expiry = cur_time + 12000;
		ip->client->new->renewal += cur_time + 8000;
		ip->client->new->rebind += cur_time + 10000;

		ip->client->state = S_REQUESTING;

		/* Bind to the address we received. */
		bind_lease(ip);
		return;
	}

	/* Go to the REQUESTING state. */
	ip->client->destination = iaddr_broadcast;
	ip->client->state = S_REQUESTING;
	ip->client->first_sending = cur_time;
	ip->client->interval = ip->client->config->initial_interval;

	/* Make a DHCPREQUEST packet from the lease we picked. */
	make_request(ip, picked);
	ip->client->xid = ip->client->packet.xid;

	/* Toss the lease we picked - we'll get it back in a DHCPACK. */
	free_client_lease(picked);

	/* Add an immediate timeout to send the first DHCPREQUEST packet. */
	send_request(ip);
}

/* state_requesting is called when we receive a DHCPACK message after
   having sent out one or more DHCPREQUEST packets. */

void
dhcpack(struct packet *packet)
{
	struct interface_info *ip = packet->interface;
	struct client_lease *lease;

	/* If we're not receptive to an offer right now, or if the offer
	   has an unrecognizable transaction id, then just drop it. */
	if (packet->interface->client->xid != packet->raw->xid ||
	    (packet->interface->hw_address.hlen != packet->raw->hlen) ||
	    (memcmp(packet->interface->hw_address.haddr,
	    packet->raw->chaddr, packet->raw->hlen)))
		return;

	if (ip->client->state != S_REBOOTING &&
	    ip->client->state != S_REQUESTING &&
	    ip->client->state != S_RENEWING &&
	    ip->client->state != S_REBINDING)
		return;

	note("DHCPACK from %s", piaddr(packet->client_addr));

	lease = packet_to_lease(packet);
	if (!lease) {
		note("packet_to_lease failed.");
		return;
	}

	ip->client->new = lease;

	/* Stop resending DHCPREQUEST. */
	cancel_timeout(send_request, ip);

	/* Figure out the lease time. */
        if (ip->client->config->default_actions[DHO_DHCP_LEASE_TIME] ==
            ACTION_SUPERSEDE)
		ip->client->new->expiry = getULong(
		    ip->client->config->defaults[DHO_DHCP_LEASE_TIME].data);
        else if (ip->client->new->options[DHO_DHCP_LEASE_TIME].len >= 4)
		ip->client->new->expiry = getULong(
		    ip->client->new->options[DHO_DHCP_LEASE_TIME].data);
	else
		ip->client->new->expiry = default_lease_time;
	/* A number that looks negative here is really just very large,
	   because the lease expiry offset is unsigned. Also make sure that
           the addition of cur_time below does not overflow (a 32 bit) time_t. */
	if (ip->client->new->expiry < 0 ||
            ip->client->new->expiry > TIME_MAX - cur_time)
		ip->client->new->expiry = TIME_MAX - cur_time;
	/* XXX should be fixed by resetting the client state */
	if (ip->client->new->expiry < 60)
		ip->client->new->expiry = 60;

        /* Unless overridden in the config, take the server-provided renewal
         * time if there is one. Otherwise figure it out according to the spec.
         * Also make sure the renewal time does not exceed the expiry time.
         */
        if (ip->client->config->default_actions[DHO_DHCP_RENEWAL_TIME] ==
            ACTION_SUPERSEDE)
		ip->client->new->renewal = getULong(
		    ip->client->config->defaults[DHO_DHCP_RENEWAL_TIME].data);
        else if (ip->client->new->options[DHO_DHCP_RENEWAL_TIME].len >= 4)
		ip->client->new->renewal = getULong(
		    ip->client->new->options[DHO_DHCP_RENEWAL_TIME].data);
	else
		ip->client->new->renewal = ip->client->new->expiry / 2;
        if (ip->client->new->renewal < 0 ||
            ip->client->new->renewal > ip->client->new->expiry / 2)
                ip->client->new->renewal = ip->client->new->expiry / 2;

	/* Same deal with the rebind time. */
        if (ip->client->config->default_actions[DHO_DHCP_REBINDING_TIME] ==
            ACTION_SUPERSEDE)
		ip->client->new->rebind = getULong(
		    ip->client->config->defaults[DHO_DHCP_REBINDING_TIME].data);
        else if (ip->client->new->options[DHO_DHCP_REBINDING_TIME].len >= 4)
		ip->client->new->rebind = getULong(
		    ip->client->new->options[DHO_DHCP_REBINDING_TIME].data);
	else
		ip->client->new->rebind = ip->client->new->renewal / 4 * 7;
	if (ip->client->new->rebind < 0 ||
            ip->client->new->rebind > ip->client->new->renewal / 4 * 7)
                ip->client->new->rebind = ip->client->new->renewal / 4 * 7;

        /* Convert the time offsets into seconds-since-the-epoch */
        ip->client->new->expiry += cur_time;
        ip->client->new->renewal += cur_time;
        ip->client->new->rebind += cur_time;

	bind_lease(ip);
}

void
bind_lease(struct interface_info *ip)
{
	struct option_data *opt;

	/* Remember the medium. */
	ip->client->new->medium = ip->client->medium;

	opt = &ip->client->new->options[DHO_INTERFACE_MTU];
	if (opt->len == sizeof(u_int16_t)) {
		u_int16_t mtu = 0;
		u_int16_t old_mtu = 0;
		bool supersede = (ip->client->config->default_actions[DHO_INTERFACE_MTU] ==
			ACTION_SUPERSEDE);

		if (supersede)
			mtu = getUShort(ip->client->config->defaults[DHO_INTERFACE_MTU].data);
		else
			mtu = be16dec(opt->data);

		if (ip->client->active) {
			opt = &ip->client->active->options[DHO_INTERFACE_MTU];
			if (opt->len == sizeof(u_int16_t)) {
				old_mtu = be16dec(opt->data);
			}
		}

		if (mtu < MIN_MTU) {
			/* Treat 0 like a user intentionally doesn't want to change MTU and,
			 * therefore, warning is not needed */
			if (!supersede || mtu != 0)
				warning("mtu size %u < %d: ignored", (unsigned)mtu, MIN_MTU);
		} else if (ip->client->state != S_RENEWING || mtu != old_mtu) {
			interface_set_mtu_unpriv(privfd, mtu);
		}
	}

	/* Write out the new lease. */
	write_client_lease(ip, ip->client->new, 0);

	/* Run the client script with the new parameters. */
	script_init((ip->client->state == S_REQUESTING ? "BOUND" :
	    (ip->client->state == S_RENEWING ? "RENEW" :
	    (ip->client->state == S_REBOOTING ? "REBOOT" : "REBIND"))),
	    ip->client->new->medium);
	if (ip->client->active && ip->client->state != S_REBOOTING)
		script_write_params("old_", ip->client->active);
	script_write_params("new_", ip->client->new);
	if (ip->client->alias)
		script_write_params("alias_", ip->client->alias);
	script_go();

	/* Replace the old active lease with the new one. */
	if (ip->client->active)
		free_client_lease(ip->client->active);
	ip->client->active = ip->client->new;
	ip->client->new = NULL;

	/* Set up a timeout to start the renewal process. */
	add_timeout(ip->client->active->renewal, state_bound, ip);

	note("bound to %s -- renewal in %d seconds.",
	    piaddr(ip->client->active->address),
	    (int)(ip->client->active->renewal - cur_time));
	ip->client->state = S_BOUND;
	reinitialize_interfaces();
	go_daemon();
}

/*
 * state_bound is called when we've successfully bound to a particular
 * lease, but the renewal time on that lease has expired.   We are
 * expected to unicast a DHCPREQUEST to the server that gave us our
 * original lease.
 */
void
state_bound(void *ipp)
{
	struct interface_info *ip = ipp;
	u_int8_t *dp = NULL;
	int len;

	ASSERT_STATE(state, S_BOUND);

	/* T1 has expired. */
	make_request(ip, ip->client->active);
	ip->client->xid = ip->client->packet.xid;

	if (ip->client->config->default_actions[DHO_DHCP_SERVER_IDENTIFIER] ==
	    ACTION_SUPERSEDE) {
		dp = ip->client->config->defaults[DHO_DHCP_SERVER_IDENTIFIER].data;
		len = ip->client->config->defaults[DHO_DHCP_SERVER_IDENTIFIER].len;
	} else {
		dp = ip->client->active->options[DHO_DHCP_SERVER_IDENTIFIER].data;
		len = ip->client->active->options[DHO_DHCP_SERVER_IDENTIFIER].len;
	}
	if (len == 4) {
		memcpy(ip->client->destination.iabuf, dp, len);
		ip->client->destination.len = len;
	} else
		ip->client->destination = iaddr_broadcast;

	ip->client->first_sending = cur_time;
	ip->client->interval = ip->client->config->initial_interval;
	ip->client->state = S_RENEWING;

	/* Send the first packet immediately. */
	send_request(ip);
}

void
bootp(struct packet *packet)
{
	struct iaddrlist *ap;

	if (packet->raw->op != BOOTREPLY)
		return;

	/* If there's a reject list, make sure this packet's sender isn't
	   on it. */
	for (ap = packet->interface->client->config->reject_list;
	    ap; ap = ap->next) {
		if (addr_eq(packet->client_addr, ap->addr)) {
			note("BOOTREPLY from %s rejected.", piaddr(ap->addr));
			return;
		}
	}
	dhcpoffer(packet);
}

void
dhcp(struct packet *packet)
{
	struct iaddrlist *ap;
	void (*handler)(struct packet *);
	const char *type;

	switch (packet->packet_type) {
	case DHCPOFFER:
		handler = dhcpoffer;
		type = "DHCPOFFER";
		break;
	case DHCPNAK:
		handler = dhcpnak;
		type = "DHCPNACK";
		break;
	case DHCPACK:
		handler = dhcpack;
		type = "DHCPACK";
		break;
	default:
		return;
	}

	/* If there's a reject list, make sure this packet's sender isn't
	   on it. */
	for (ap = packet->interface->client->config->reject_list;
	    ap; ap = ap->next) {
		if (addr_eq(packet->client_addr, ap->addr)) {
			note("%s from %s rejected.", type, piaddr(ap->addr));
			return;
		}
	}
	(*handler)(packet);
}

void
dhcpoffer(struct packet *packet)
{
	struct interface_info *ip = packet->interface;
	struct client_lease *lease, *lp;
	int i;
	struct timespec arp_timeout_needed;
	time_t stop_selecting;
	struct timespec stop_time;
	const char *name = packet->options[DHO_DHCP_MESSAGE_TYPE].len ?
	    "DHCPOFFER" : "BOOTREPLY";

	clock_gettime(CLOCK_MONOTONIC, &time_now);

	/* If we're not receptive to an offer right now, or if the offer
	   has an unrecognizable transaction id, then just drop it. */
	if (ip->client->state != S_SELECTING ||
	    packet->interface->client->xid != packet->raw->xid ||
	    (packet->interface->hw_address.hlen != packet->raw->hlen) ||
	    (memcmp(packet->interface->hw_address.haddr,
	    packet->raw->chaddr, packet->raw->hlen)))
		return;

	note("%s from %s", name, piaddr(packet->client_addr));


	/* If this lease doesn't supply the minimum required parameters,
	   blow it off. */
	for (i = 0; ip->client->config->required_options[i]; i++) {
		if (!packet->options[ip->client->config->
		    required_options[i]].len) {
			note("%s isn't satisfactory.", name);
			return;
		}
	}

	/* If we've already seen this lease, don't record it again. */
	for (lease = ip->client->offered_leases;
	    lease; lease = lease->next) {
		if (lease->address.len == sizeof(packet->raw->yiaddr) &&
		    !memcmp(lease->address.iabuf,
		    &packet->raw->yiaddr, lease->address.len)) {
			debug("%s already seen.", name);
			return;
		}
	}

	lease = packet_to_lease(packet);
	if (!lease) {
		note("packet_to_lease failed.");
		return;
	}

	/* If this lease was acquired through a BOOTREPLY, record that
	   fact. */
	if (!packet->options[DHO_DHCP_MESSAGE_TYPE].len)
		lease->is_bootp = 1;

	/* Record the medium under which this lease was offered. */
	lease->medium = ip->client->medium;

	/* Send out an ARP Request for the offered IP address. */
	script_init("ARPSEND", lease->medium);
	script_write_params("check_", lease);
	/* If the script can't send an ARP request without waiting,
	   we'll be waiting when we do the ARPCHECK, so don't wait now. */
	if (script_go())
		arp_timeout_needed = zero_timespec;

	else
		arp_timeout_needed = arp_timeout;

	/* Figure out when we're supposed to stop selecting. */
	stop_selecting =
	    ip->client->first_sending + ip->client->config->select_interval;

	/* If this is the lease we asked for, put it at the head of the
	   list, and don't mess with the arp request timeout. */
	if (lease->address.len == ip->client->requested_address.len &&
	    !memcmp(lease->address.iabuf,
	    ip->client->requested_address.iabuf,
	    ip->client->requested_address.len)) {
		lease->next = ip->client->offered_leases;
		ip->client->offered_leases = lease;
	} else {
		/* If we already have an offer, and arping for this
		   offer would take us past the selection timeout,
		   then don't extend the timeout - just hope for the
		   best. */

		struct timespec interm_struct;
		timespecadd(&time_now, &arp_timeout_needed, &interm_struct);

		if (ip->client->offered_leases &&
		    interm_struct.tv_sec >= stop_selecting)
			arp_timeout_needed = zero_timespec;

		/* Put the lease at the end of the list. */
		lease->next = NULL;
		if (!ip->client->offered_leases)
			ip->client->offered_leases = lease;
		else {
			for (lp = ip->client->offered_leases; lp->next;
			    lp = lp->next)
				;	/* nothing */
			lp->next = lease;
		}
	}

	/*
	 * Wait until stop_selecting seconds past the epoch, or until
	 * arp_timeout_needed past now, whichever is longer.  Note that
	 * the first case only occurs if select-timeout is set to nonzero
	 * in dhclient.conf.
	 */
	struct timespec time_left =
	    {.tv_sec = stop_selecting - cur_time, .tv_nsec = 0};
	if (timespeccmp(&time_left, &arp_timeout_needed, <)) {
		timespecadd(&time_now, &arp_timeout_needed, &stop_time);
	} else {
		timespecadd(&time_now, &time_left, &stop_time);
	}
	add_timeout_timespec(stop_time, state_selecting, ip);
	cancel_timeout(send_discover, ip);
}

/* Allocate a client_lease structure and initialize it from the parameters
   in the specified packet. */

struct client_lease *
packet_to_lease(struct packet *packet)
{
	struct client_lease *lease;
	int i;

	lease = malloc(sizeof(struct client_lease));

	if (!lease) {
		warning("dhcpoffer: no memory to record lease.");
		return (NULL);
	}

	memset(lease, 0, sizeof(*lease));

	/* Copy the lease options. */
	for (i = 0; i < 256; i++) {
		if (packet->options[i].len) {
			lease->options[i].data =
			    malloc(packet->options[i].len + 1);
			if (!lease->options[i].data) {
				warning("dhcpoffer: no memory for option %d", i);
				free_client_lease(lease);
				return (NULL);
			} else {
				memcpy(lease->options[i].data,
				    packet->options[i].data,
				    packet->options[i].len);
				lease->options[i].len =
				    packet->options[i].len;
				lease->options[i].data[lease->options[i].len] =
				    0;
			}
			if (!check_option(lease,i)) {
				/* ignore a bogus lease offer */
				warning("Invalid lease option - ignoring offer");
				free_client_lease(lease);
				return (NULL);
			}
		}
	}

	lease->address.len = sizeof(packet->raw->yiaddr);
	memcpy(lease->address.iabuf, &packet->raw->yiaddr, lease->address.len);

	lease->nextserver.len = sizeof(packet->raw->siaddr);
	memcpy(lease->nextserver.iabuf, &packet->raw->siaddr, lease->nextserver.len);

	/* If the server name was filled out, copy it.
	   Do not attempt to validate the server name as a host name.
	   RFC 2131 merely states that sname is NUL-terminated (which do
	   do not assume) and that it is the server's host name.  Since
	   the ISC client and server allow arbitrary characters, we do
	   as well. */
	if ((!packet->options[DHO_DHCP_OPTION_OVERLOAD].len ||
	    !(packet->options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 2)) &&
	    packet->raw->sname[0]) {
		lease->server_name = malloc(DHCP_SNAME_LEN + 1);
		if (!lease->server_name) {
			warning("dhcpoffer: no memory for server name.");
			free_client_lease(lease);
			return (NULL);
		}
		memcpy(lease->server_name, packet->raw->sname, DHCP_SNAME_LEN);
		lease->server_name[DHCP_SNAME_LEN]='\0';
	}

	/* Ditto for the filename. */
	if ((!packet->options[DHO_DHCP_OPTION_OVERLOAD].len ||
	    !(packet->options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 1)) &&
	    packet->raw->file[0]) {
		/* Don't count on the NUL terminator. */
		lease->filename = malloc(DHCP_FILE_LEN + 1);
		if (!lease->filename) {
			warning("dhcpoffer: no memory for filename.");
			free_client_lease(lease);
			return (NULL);
		}
		memcpy(lease->filename, packet->raw->file, DHCP_FILE_LEN);
		lease->filename[DHCP_FILE_LEN]='\0';
	}
	return lease;
}

void
dhcpnak(struct packet *packet)
{
	struct interface_info *ip = packet->interface;

	/* If we're not receptive to an offer right now, or if the offer
	   has an unrecognizable transaction id, then just drop it. */
	if (packet->interface->client->xid != packet->raw->xid ||
	    (packet->interface->hw_address.hlen != packet->raw->hlen) ||
	    (memcmp(packet->interface->hw_address.haddr,
	    packet->raw->chaddr, packet->raw->hlen)))
		return;

	if (ip->client->state != S_REBOOTING &&
	    ip->client->state != S_REQUESTING &&
	    ip->client->state != S_RENEWING &&
	    ip->client->state != S_REBINDING)
		return;

	note("DHCPNAK from %s", piaddr(packet->client_addr));

	if (!ip->client->active) {
		note("DHCPNAK with no active lease.\n");
		return;
	}

	free_client_lease(ip->client->active);
	ip->client->active = NULL;

	/* Stop sending DHCPREQUEST packets... */
	cancel_timeout(send_request, ip);

	ip->client->state = S_INIT;
	state_init(ip);
}

/* Send out a DHCPDISCOVER packet, and set a timeout to send out another
   one after the right interval has expired.  If we don't get an offer by
   the time we reach the panic interval, call the panic function. */

void
send_discover(void *ipp)
{
	struct interface_info *ip = ipp;
	int interval, increase = 1;

	/* Figure out how long it's been since we started transmitting. */
	interval = cur_time - ip->client->first_sending;

	/* If we're past the panic timeout, call the script and tell it
	   we haven't found anything for this interface yet. */
	if (interval > ip->client->config->timeout) {
		state_panic(ip);
		return;
	}

	/* If we're selecting media, try the whole list before doing
	   the exponential backoff, but if we've already received an
	   offer, stop looping, because we obviously have it right. */
	if (!ip->client->offered_leases &&
	    ip->client->config->media) {
		int fail = 0;
again:
		if (ip->client->medium) {
			ip->client->medium = ip->client->medium->next;
			increase = 0;
		}
		if (!ip->client->medium) {
			if (fail)
				error("No valid media types for %s!", ip->name);
			ip->client->medium = ip->client->config->media;
			increase = 1;
		}

		note("Trying medium \"%s\" %d", ip->client->medium->string,
		    increase);
		script_init("MEDIUM", ip->client->medium);
		if (script_go())
			goto again;
	}

	/*
	 * If we're supposed to increase the interval, do so.  If it's
	 * currently zero (i.e., we haven't sent any packets yet), set
	 * it to one; otherwise, add to it a random number between zero
	 * and two times itself.  On average, this means that it will
	 * double with every transmission.
	 */
	if (increase) {
		if (!ip->client->interval)
			ip->client->interval =
			    ip->client->config->initial_interval;
		else {
			ip->client->interval += (arc4random() >> 2) %
			    (2 * ip->client->interval);
		}

		/* Don't backoff past cutoff. */
		if (ip->client->interval >
		    ip->client->config->backoff_cutoff)
			ip->client->interval =
				((ip->client->config->backoff_cutoff / 2)
				 + ((arc4random() >> 2) %
				    ip->client->config->backoff_cutoff));
	} else if (!ip->client->interval)
		ip->client->interval =
			ip->client->config->initial_interval;

	/* If the backoff would take us to the panic timeout, just use that
	   as the interval. */
	if (cur_time + ip->client->interval >
	    ip->client->first_sending + ip->client->config->timeout)
		ip->client->interval =
			(ip->client->first_sending +
			 ip->client->config->timeout) - cur_time + 1;

	/* Record the number of seconds since we started sending. */
	if (interval < 65536)
		ip->client->packet.secs = htons(interval);
	else
		ip->client->packet.secs = htons(65535);
	ip->client->secs = ip->client->packet.secs;

	note("DHCPDISCOVER on %s to %s port %d interval %d",
	    ip->name, inet_ntoa(inaddr_broadcast), REMOTE_PORT,
	    (int)ip->client->interval);

	/* Send out a packet. */
	send_packet_unpriv(privfd, &ip->client->packet,
	    ip->client->packet_length, inaddr_any, inaddr_broadcast);

	add_timeout(cur_time + ip->client->interval, send_discover, ip);
}

/*
 * state_panic gets called if we haven't received any offers in a preset
 * amount of time.   When this happens, we try to use existing leases
 * that haven't yet expired, and failing that, we call the client script
 * and hope it can do something.
 */
void
state_panic(void *ipp)
{
	struct interface_info *ip = ipp;
	struct client_lease *loop = ip->client->active;
	struct client_lease *lp;

	note("No DHCPOFFERS received.");

	/* We may not have an active lease, but we may have some
	   predefined leases that we can try. */
	if (!ip->client->active && ip->client->leases)
		goto activate_next;

	/* Run through the list of leases and see if one can be used. */
	while (ip->client->active) {
		if (ip->client->active->expiry > cur_time) {
			note("Trying recorded lease %s",
			    piaddr(ip->client->active->address));
			/* Run the client script with the existing
			   parameters. */
			script_init("TIMEOUT",
			    ip->client->active->medium);
			script_write_params("new_", ip->client->active);
			if (ip->client->alias)
				script_write_params("alias_",
				    ip->client->alias);

			/* If the old lease is still good and doesn't
			   yet need renewal, go into BOUND state and
			   timeout at the renewal time. */
			if (!script_go()) {
				if (cur_time <
				    ip->client->active->renewal) {
					ip->client->state = S_BOUND;
					note("bound: renewal in %d seconds.",
					    (int)(ip->client->active->renewal -
					    cur_time));
					add_timeout(
					    ip->client->active->renewal,
					    state_bound, ip);
				} else {
					ip->client->state = S_BOUND;
					note("bound: immediate renewal.");
					state_bound(ip);
				}
				reinitialize_interfaces();
				go_daemon();
				return;
			}
		}

		/* If there are no other leases, give up. */
		if (!ip->client->leases) {
			ip->client->leases = ip->client->active;
			ip->client->active = NULL;
			break;
		}

activate_next:
		/* Otherwise, put the active lease at the end of the
		   lease list, and try another lease.. */
		for (lp = ip->client->leases; lp->next; lp = lp->next)
			;
		lp->next = ip->client->active;
		if (lp->next)
			lp->next->next = NULL;
		ip->client->active = ip->client->leases;
		ip->client->leases = ip->client->leases->next;

		/* If we already tried this lease, we've exhausted the
		   set of leases, so we might as well give up for
		   now. */
		if (ip->client->active == loop)
			break;
		else if (!loop)
			loop = ip->client->active;
	}

	/* No leases were available, or what was available didn't work, so
	   tell the shell script that we failed to allocate an address,
	   and try again later. */
	note("No working leases in persistent database - sleeping.\n");
	script_init("FAIL", NULL);
	if (ip->client->alias)
		script_write_params("alias_", ip->client->alias);
	script_go();
	ip->client->state = S_INIT;
	add_timeout(cur_time + ip->client->config->retry_interval, state_init,
	    ip);
	go_daemon();
}

void
send_request(void *ipp)
{
	struct interface_info *ip = ipp;
	struct in_addr from, to;
	int interval;

	/* Figure out how long it's been since we started transmitting. */
	interval = cur_time - ip->client->first_sending;

	/* If we're in the INIT-REBOOT or REQUESTING state and we're
	   past the reboot timeout, go to INIT and see if we can
	   DISCOVER an address... */
	/* XXX In the INIT-REBOOT state, if we don't get an ACK, it
	   means either that we're on a network with no DHCP server,
	   or that our server is down.  In the latter case, assuming
	   that there is a backup DHCP server, DHCPDISCOVER will get
	   us a new address, but we could also have successfully
	   reused our old address.  In the former case, we're hosed
	   anyway.  This is not a win-prone situation. */
	if ((ip->client->state == S_REBOOTING ||
	    ip->client->state == S_REQUESTING) &&
	    interval > ip->client->config->reboot_timeout) {
cancel:
		ip->client->state = S_INIT;
		cancel_timeout(send_request, ip);
		state_init(ip);
		return;
	}

	/* If we're in the reboot state, make sure the media is set up
	   correctly. */
	if (ip->client->state == S_REBOOTING &&
	    !ip->client->medium &&
	    ip->client->active->medium ) {
		script_init("MEDIUM", ip->client->active->medium);

		/* If the medium we chose won't fly, go to INIT state. */
		if (script_go())
			goto cancel;

		/* Record the medium. */
		ip->client->medium = ip->client->active->medium;
	}

	/* If the lease has expired, relinquish the address and go back
	   to the INIT state. */
	if (ip->client->state != S_REQUESTING &&
	    cur_time > ip->client->active->expiry) {
		/* Run the client script with the new parameters. */
		script_init("EXPIRE", NULL);
		script_write_params("old_", ip->client->active);
		if (ip->client->alias)
			script_write_params("alias_", ip->client->alias);
		script_go();

		/* Now do a preinit on the interface so that we can
		   discover a new address. */
		script_init("PREINIT", NULL);
		if (ip->client->alias)
			script_write_params("alias_", ip->client->alias);
		script_go();

		ip->client->state = S_INIT;
		state_init(ip);
		return;
	}

	/* Do the exponential backoff... */
	if (!ip->client->interval)
		ip->client->interval = ip->client->config->initial_interval;
	else
		ip->client->interval += ((arc4random() >> 2) %
		    (2 * ip->client->interval));

	/* Don't backoff past cutoff. */
	if (ip->client->interval >
	    ip->client->config->backoff_cutoff)
		ip->client->interval =
		    ((ip->client->config->backoff_cutoff / 2) +
		    ((arc4random() >> 2) % ip->client->interval));

	/* If the backoff would take us to the expiry time, just set the
	   timeout to the expiry time. */
	if (ip->client->state != S_REQUESTING &&
	    cur_time + ip->client->interval >
	    ip->client->active->expiry)
		ip->client->interval =
		    ip->client->active->expiry - cur_time + 1;

	/* If the lease T2 time has elapsed, or if we're not yet bound,
	   broadcast the DHCPREQUEST rather than unicasting. */
	if (ip->client->state == S_REQUESTING ||
	    ip->client->state == S_REBOOTING ||
	    cur_time > ip->client->active->rebind)
		to.s_addr = INADDR_BROADCAST;
	else
		memcpy(&to.s_addr, ip->client->destination.iabuf,
		    sizeof(to.s_addr));

	if (ip->client->state != S_REQUESTING &&
	    ip->client->state != S_REBOOTING)
		memcpy(&from, ip->client->active->address.iabuf,
		    sizeof(from));
	else
		from.s_addr = INADDR_ANY;

	/* Record the number of seconds since we started sending. */
	if (ip->client->state == S_REQUESTING)
		ip->client->packet.secs = ip->client->secs;
	else {
		if (interval < 65536)
			ip->client->packet.secs = htons(interval);
		else
			ip->client->packet.secs = htons(65535);
	}

	note("DHCPREQUEST on %s to %s port %d", ip->name, inet_ntoa(to),
	    REMOTE_PORT);

	/* Send out a packet. */
	send_packet_unpriv(privfd, &ip->client->packet,
	    ip->client->packet_length, from, to);

	add_timeout(cur_time + ip->client->interval, send_request, ip);
}

void
send_decline(void *ipp)
{
	struct interface_info *ip = ipp;

	note("DHCPDECLINE on %s to %s port %d", ip->name,
	    inet_ntoa(inaddr_broadcast), REMOTE_PORT);

	/* Send out a packet. */
	send_packet_unpriv(privfd, &ip->client->packet,
	    ip->client->packet_length, inaddr_any, inaddr_broadcast);
}

void
make_discover(struct interface_info *ip, struct client_lease *lease)
{
	unsigned char discover = DHCPDISCOVER;
	struct tree_cache *options[256];
	struct tree_cache option_elements[256];
	int i;

	memset(option_elements, 0, sizeof(option_elements));
	memset(options, 0, sizeof(options));
	memset(&ip->client->packet, 0, sizeof(ip->client->packet));

	/* Set DHCP_MESSAGE_TYPE to DHCPDISCOVER */
	i = DHO_DHCP_MESSAGE_TYPE;
	options[i] = &option_elements[i];
	options[i]->value = &discover;
	options[i]->len = sizeof(discover);
	options[i]->buf_size = sizeof(discover);
	options[i]->timeout = 0xFFFFFFFF;

	/* Request the options we want */
	i  = DHO_DHCP_PARAMETER_REQUEST_LIST;
	options[i] = &option_elements[i];
	options[i]->value = ip->client->config->requested_options;
	options[i]->len = ip->client->config->requested_option_count;
	options[i]->buf_size =
		ip->client->config->requested_option_count;
	options[i]->timeout = 0xFFFFFFFF;

	/* If we had an address, try to get it again. */
	if (lease) {
		ip->client->requested_address = lease->address;
		i = DHO_DHCP_REQUESTED_ADDRESS;
		options[i] = &option_elements[i];
		options[i]->value = lease->address.iabuf;
		options[i]->len = lease->address.len;
		options[i]->buf_size = lease->address.len;
		options[i]->timeout = 0xFFFFFFFF;
	} else
		ip->client->requested_address.len = 0;

	/* Send any options requested in the config file. */
	for (i = 0; i < 256; i++)
		if (!options[i] &&
		    ip->client->config->send_options[i].data) {
			options[i] = &option_elements[i];
			options[i]->value =
			    ip->client->config->send_options[i].data;
			options[i]->len =
			    ip->client->config->send_options[i].len;
			options[i]->buf_size =
			    ip->client->config->send_options[i].len;
			options[i]->timeout = 0xFFFFFFFF;
		}

	/* send host name if not set via config file. */
	if (!options[DHO_HOST_NAME]) {
		if (hostname[0] != '\0') {
			size_t len;
			char* posDot = strchr(hostname, '.');
			if (posDot != NULL)
				len = posDot - hostname;
			else
				len = strlen(hostname);
			options[DHO_HOST_NAME] = &option_elements[DHO_HOST_NAME];
			options[DHO_HOST_NAME]->value = hostname;
			options[DHO_HOST_NAME]->len = len;
			options[DHO_HOST_NAME]->buf_size = len;
			options[DHO_HOST_NAME]->timeout = 0xFFFFFFFF;
		}
	}

	/* set unique client identifier */
	char client_ident[sizeof(ip->hw_address.haddr) + 1];
	if (!options[DHO_DHCP_CLIENT_IDENTIFIER]) {
		int hwlen = (ip->hw_address.hlen < sizeof(client_ident)-1) ?
				ip->hw_address.hlen : sizeof(client_ident)-1;
		client_ident[0] = ip->hw_address.htype;
		memcpy(&client_ident[1], ip->hw_address.haddr, hwlen);
		options[DHO_DHCP_CLIENT_IDENTIFIER] = &option_elements[DHO_DHCP_CLIENT_IDENTIFIER];
		options[DHO_DHCP_CLIENT_IDENTIFIER]->value = client_ident;
		options[DHO_DHCP_CLIENT_IDENTIFIER]->len = hwlen+1;
		options[DHO_DHCP_CLIENT_IDENTIFIER]->buf_size = hwlen+1;
		options[DHO_DHCP_CLIENT_IDENTIFIER]->timeout = 0xFFFFFFFF;
	}

	/* Set up the option buffer... */
	ip->client->packet_length = cons_options(NULL, &ip->client->packet, 0,
	    options, 0, 0, 0, NULL, 0);
	if (ip->client->packet_length < BOOTP_MIN_LEN)
		ip->client->packet_length = BOOTP_MIN_LEN;

	ip->client->packet.op = BOOTREQUEST;
	ip->client->packet.htype = ip->hw_address.htype;
	ip->client->packet.hlen = ip->hw_address.hlen;
	ip->client->packet.hops = 0;
	ip->client->packet.xid = arc4random();
	ip->client->packet.secs = 0; /* filled in by send_discover. */
	ip->client->packet.flags = 0;

	memset(&(ip->client->packet.ciaddr),
	    0, sizeof(ip->client->packet.ciaddr));
	memset(&(ip->client->packet.yiaddr),
	    0, sizeof(ip->client->packet.yiaddr));
	memset(&(ip->client->packet.siaddr),
	    0, sizeof(ip->client->packet.siaddr));
	memset(&(ip->client->packet.giaddr),
	    0, sizeof(ip->client->packet.giaddr));
	memcpy(ip->client->packet.chaddr,
	    ip->hw_address.haddr, ip->hw_address.hlen);
}


void
make_request(struct interface_info *ip, struct client_lease * lease)
{
	unsigned char request = DHCPREQUEST;
	struct tree_cache *options[256];
	struct tree_cache option_elements[256];
	int i;

	memset(options, 0, sizeof(options));
	memset(&ip->client->packet, 0, sizeof(ip->client->packet));

	/* Set DHCP_MESSAGE_TYPE to DHCPREQUEST */
	i = DHO_DHCP_MESSAGE_TYPE;
	options[i] = &option_elements[i];
	options[i]->value = &request;
	options[i]->len = sizeof(request);
	options[i]->buf_size = sizeof(request);
	options[i]->timeout = 0xFFFFFFFF;

	/* Request the options we want */
	i = DHO_DHCP_PARAMETER_REQUEST_LIST;
	options[i] = &option_elements[i];
	options[i]->value = ip->client->config->requested_options;
	options[i]->len = ip->client->config->requested_option_count;
	options[i]->buf_size =
		ip->client->config->requested_option_count;
	options[i]->timeout = 0xFFFFFFFF;

	/* If we are requesting an address that hasn't yet been assigned
	   to us, use the DHCP Requested Address option. */
	if (ip->client->state == S_REQUESTING) {
		/* Send back the server identifier... */
		i = DHO_DHCP_SERVER_IDENTIFIER;
		options[i] = &option_elements[i];
		options[i]->value = lease->options[i].data;
		options[i]->len = lease->options[i].len;
		options[i]->buf_size = lease->options[i].len;
		options[i]->timeout = 0xFFFFFFFF;
	}
	if (ip->client->state == S_REQUESTING ||
	    ip->client->state == S_REBOOTING) {
		ip->client->requested_address = lease->address;
		i = DHO_DHCP_REQUESTED_ADDRESS;
		options[i] = &option_elements[i];
		options[i]->value = lease->address.iabuf;
		options[i]->len = lease->address.len;
		options[i]->buf_size = lease->address.len;
		options[i]->timeout = 0xFFFFFFFF;
	} else
		ip->client->requested_address.len = 0;

	/* Send any options requested in the config file. */
	for (i = 0; i < 256; i++)
		if (!options[i] &&
		    ip->client->config->send_options[i].data) {
			options[i] = &option_elements[i];
			options[i]->value =
			    ip->client->config->send_options[i].data;
			options[i]->len =
			    ip->client->config->send_options[i].len;
			options[i]->buf_size =
			    ip->client->config->send_options[i].len;
			options[i]->timeout = 0xFFFFFFFF;
		}

	/* send host name if not set via config file. */
	if (!options[DHO_HOST_NAME]) {
		if (hostname[0] != '\0') {
			size_t len;
			char* posDot = strchr(hostname, '.');
			if (posDot != NULL)
				len = posDot - hostname;
			else
				len = strlen(hostname);
			options[DHO_HOST_NAME] = &option_elements[DHO_HOST_NAME];
			options[DHO_HOST_NAME]->value = hostname;
			options[DHO_HOST_NAME]->len = len;
			options[DHO_HOST_NAME]->buf_size = len;
			options[DHO_HOST_NAME]->timeout = 0xFFFFFFFF;
		}
	}

	/* set unique client identifier */
	char client_ident[sizeof(ip->hw_address.haddr) + 1];
	if (!options[DHO_DHCP_CLIENT_IDENTIFIER]) {
		int hwlen = (ip->hw_address.hlen < sizeof(client_ident)-1) ?
				ip->hw_address.hlen : sizeof(client_ident)-1;
		client_ident[0] = ip->hw_address.htype;
		memcpy(&client_ident[1], ip->hw_address.haddr, hwlen);
		options[DHO_DHCP_CLIENT_IDENTIFIER] = &option_elements[DHO_DHCP_CLIENT_IDENTIFIER];
		options[DHO_DHCP_CLIENT_IDENTIFIER]->value = client_ident;
		options[DHO_DHCP_CLIENT_IDENTIFIER]->len = hwlen+1;
		options[DHO_DHCP_CLIENT_IDENTIFIER]->buf_size = hwlen+1;
		options[DHO_DHCP_CLIENT_IDENTIFIER]->timeout = 0xFFFFFFFF;
	}

	/* Set up the option buffer... */
	ip->client->packet_length = cons_options(NULL, &ip->client->packet, 0,
	    options, 0, 0, 0, NULL, 0);
	if (ip->client->packet_length < BOOTP_MIN_LEN)
		ip->client->packet_length = BOOTP_MIN_LEN;

	ip->client->packet.op = BOOTREQUEST;
	ip->client->packet.htype = ip->hw_address.htype;
	ip->client->packet.hlen = ip->hw_address.hlen;
	ip->client->packet.hops = 0;
	ip->client->packet.xid = ip->client->xid;
	ip->client->packet.secs = 0; /* Filled in by send_request. */

	/* If we own the address we're requesting, put it in ciaddr;
	   otherwise set ciaddr to zero. */
	if (ip->client->state == S_BOUND ||
	    ip->client->state == S_RENEWING ||
	    ip->client->state == S_REBINDING) {
		memcpy(&ip->client->packet.ciaddr,
		    lease->address.iabuf, lease->address.len);
		ip->client->packet.flags = 0;
	} else {
		memset(&ip->client->packet.ciaddr, 0,
		    sizeof(ip->client->packet.ciaddr));
		ip->client->packet.flags = 0;
	}

	memset(&ip->client->packet.yiaddr, 0,
	    sizeof(ip->client->packet.yiaddr));
	memset(&ip->client->packet.siaddr, 0,
	    sizeof(ip->client->packet.siaddr));
	memset(&ip->client->packet.giaddr, 0,
	    sizeof(ip->client->packet.giaddr));
	memcpy(ip->client->packet.chaddr,
	    ip->hw_address.haddr, ip->hw_address.hlen);
}

void
make_decline(struct interface_info *ip, struct client_lease *lease)
{
	struct tree_cache *options[256], message_type_tree;
	struct tree_cache requested_address_tree;
	struct tree_cache server_id_tree, client_id_tree;
	unsigned char decline = DHCPDECLINE;
	int i;

	memset(options, 0, sizeof(options));
	memset(&ip->client->packet, 0, sizeof(ip->client->packet));

	/* Set DHCP_MESSAGE_TYPE to DHCPDECLINE */
	i = DHO_DHCP_MESSAGE_TYPE;
	options[i] = &message_type_tree;
	options[i]->value = &decline;
	options[i]->len = sizeof(decline);
	options[i]->buf_size = sizeof(decline);
	options[i]->timeout = 0xFFFFFFFF;

	/* Send back the server identifier... */
	i = DHO_DHCP_SERVER_IDENTIFIER;
	options[i] = &server_id_tree;
	options[i]->value = lease->options[i].data;
	options[i]->len = lease->options[i].len;
	options[i]->buf_size = lease->options[i].len;
	options[i]->timeout = 0xFFFFFFFF;

	/* Send back the address we're declining. */
	i = DHO_DHCP_REQUESTED_ADDRESS;
	options[i] = &requested_address_tree;
	options[i]->value = lease->address.iabuf;
	options[i]->len = lease->address.len;
	options[i]->buf_size = lease->address.len;
	options[i]->timeout = 0xFFFFFFFF;

	/* Send the uid if the user supplied one. */
	i = DHO_DHCP_CLIENT_IDENTIFIER;
	if (ip->client->config->send_options[i].len) {
		options[i] = &client_id_tree;
		options[i]->value = ip->client->config->send_options[i].data;
		options[i]->len = ip->client->config->send_options[i].len;
		options[i]->buf_size = ip->client->config->send_options[i].len;
		options[i]->timeout = 0xFFFFFFFF;
	}


	/* Set up the option buffer... */
	ip->client->packet_length = cons_options(NULL, &ip->client->packet, 0,
	    options, 0, 0, 0, NULL, 0);
	if (ip->client->packet_length < BOOTP_MIN_LEN)
		ip->client->packet_length = BOOTP_MIN_LEN;

	ip->client->packet.op = BOOTREQUEST;
	ip->client->packet.htype = ip->hw_address.htype;
	ip->client->packet.hlen = ip->hw_address.hlen;
	ip->client->packet.hops = 0;
	ip->client->packet.xid = ip->client->xid;
	ip->client->packet.secs = 0; /* Filled in by send_request. */
	ip->client->packet.flags = 0;

	/* ciaddr must always be zero. */
	memset(&ip->client->packet.ciaddr, 0,
	    sizeof(ip->client->packet.ciaddr));
	memset(&ip->client->packet.yiaddr, 0,
	    sizeof(ip->client->packet.yiaddr));
	memset(&ip->client->packet.siaddr, 0,
	    sizeof(ip->client->packet.siaddr));
	memset(&ip->client->packet.giaddr, 0,
	    sizeof(ip->client->packet.giaddr));
	memcpy(ip->client->packet.chaddr,
	    ip->hw_address.haddr, ip->hw_address.hlen);
}

void
free_client_lease(struct client_lease *lease)
{
	int i;

	if (lease->server_name)
		free(lease->server_name);
	if (lease->filename)
		free(lease->filename);
	for (i = 0; i < 256; i++) {
		if (lease->options[i].len)
			free(lease->options[i].data);
	}
	free(lease);
}

static FILE *leaseFile;

void
rewrite_client_leases(void)
{
	struct client_lease *lp;
	cap_rights_t rights;

	if (!leaseFile) {
		leaseFile = fopen(path_dhclient_db, "w");
		if (!leaseFile)
			error("can't create %s: %m", path_dhclient_db);
		cap_rights_init(&rights, CAP_FCNTL, CAP_FSTAT, CAP_FSYNC,
		    CAP_FTRUNCATE, CAP_SEEK, CAP_WRITE);
		if (caph_rights_limit(fileno(leaseFile), &rights) < 0) {
			error("can't limit lease descriptor: %m");
		}
		if (caph_fcntls_limit(fileno(leaseFile), CAP_FCNTL_GETFL) < 0) {
			error("can't limit lease descriptor fcntls: %m");
		}
	} else {
		fflush(leaseFile);
		rewind(leaseFile);
	}

	for (lp = ifi->client->leases; lp; lp = lp->next)
		write_client_lease(ifi, lp, 1);
	if (ifi->client->active)
		write_client_lease(ifi, ifi->client->active, 1);

	fflush(leaseFile);
	ftruncate(fileno(leaseFile), ftello(leaseFile));
	fsync(fileno(leaseFile));
}

void
write_client_lease(struct interface_info *ip, struct client_lease *lease,
    int rewrite)
{
	static int leases_written;
	struct tm *t;
	int i;

	if (!rewrite) {
		if (leases_written++ > 20) {
			rewrite_client_leases();
			leases_written = 0;
		}
	}

	/* If the lease came from the config file, we don't need to stash
	   a copy in the lease database. */
	if (lease->is_static)
		return;

	if (!leaseFile) {	/* XXX */
		leaseFile = fopen(path_dhclient_db, "w");
		if (!leaseFile)
			error("can't create %s: %m", path_dhclient_db);
	}

	fprintf(leaseFile, "lease {\n");
	if (lease->is_bootp)
		fprintf(leaseFile, "  bootp;\n");
	fprintf(leaseFile, "  interface \"%s\";\n", ip->name);
	fprintf(leaseFile, "  fixed-address %s;\n", piaddr(lease->address));
	if (lease->nextserver.len == sizeof(inaddr_any) &&
	    0 != memcmp(lease->nextserver.iabuf, &inaddr_any,
	    sizeof(inaddr_any)))
		fprintf(leaseFile, "  next-server %s;\n",
		    piaddr(lease->nextserver));
	if (lease->filename)
		fprintf(leaseFile, "  filename \"%s\";\n", lease->filename);
	if (lease->server_name)
		fprintf(leaseFile, "  server-name \"%s\";\n",
		    lease->server_name);
	if (lease->medium)
		fprintf(leaseFile, "  medium \"%s\";\n", lease->medium->string);
	for (i = 0; i < 256; i++)
		if (lease->options[i].len)
			fprintf(leaseFile, "  option %s %s;\n",
			    dhcp_options[i].name,
			    pretty_print_option(i, lease->options[i].data,
			    lease->options[i].len, 1, 1));

	t = gmtime(&lease->renewal);
	fprintf(leaseFile, "  renew %d %d/%d/%d %02d:%02d:%02d;\n",
	    t->tm_wday, t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
	    t->tm_hour, t->tm_min, t->tm_sec);
	t = gmtime(&lease->rebind);
	fprintf(leaseFile, "  rebind %d %d/%d/%d %02d:%02d:%02d;\n",
	    t->tm_wday, t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
	    t->tm_hour, t->tm_min, t->tm_sec);
	t = gmtime(&lease->expiry);
	fprintf(leaseFile, "  expire %d %d/%d/%d %02d:%02d:%02d;\n",
	    t->tm_wday, t->tm_year + 1900, t->tm_mon + 1, t->tm_mday,
	    t->tm_hour, t->tm_min, t->tm_sec);
	fprintf(leaseFile, "}\n");
	fflush(leaseFile);
}

void
script_init(const char *reason, struct string_list *medium)
{
	size_t		 len, mediumlen = 0;
	struct imsg_hdr	 hdr;
	struct buf	*buf;
	int		 errs;

	if (medium != NULL && medium->string != NULL)
		mediumlen = strlen(medium->string);

	hdr.code = IMSG_SCRIPT_INIT;
	hdr.len = sizeof(struct imsg_hdr) +
	    sizeof(size_t) + mediumlen +
	    sizeof(size_t) + strlen(reason);

	if ((buf = buf_open(hdr.len)) == NULL)
		error("buf_open: %m");

	errs = 0;
	errs += buf_add(buf, &hdr, sizeof(hdr));
	errs += buf_add(buf, &mediumlen, sizeof(mediumlen));
	if (mediumlen > 0)
		errs += buf_add(buf, medium->string, mediumlen);
	len = strlen(reason);
	errs += buf_add(buf, &len, sizeof(len));
	errs += buf_add(buf, reason, len);

	if (errs)
		error("buf_add: %m");

	if (buf_close(privfd, buf) == -1)
		error("buf_close: %m");
}

void
priv_script_init(const char *reason, char *medium)
{
	struct interface_info *ip = ifi;

	if (ip) {
		ip->client->scriptEnvsize = 100;
		if (ip->client->scriptEnv == NULL)
			ip->client->scriptEnv =
			    malloc(ip->client->scriptEnvsize * sizeof(char *));
		if (ip->client->scriptEnv == NULL)
			error("script_init: no memory for environment");

		ip->client->scriptEnv[0] = strdup(CLIENT_PATH);
		if (ip->client->scriptEnv[0] == NULL)
			error("script_init: no memory for environment");

		ip->client->scriptEnv[1] = NULL;

		script_set_env(ip->client, "", "interface", ip->name);

		if (medium)
			script_set_env(ip->client, "", "medium", medium);

		script_set_env(ip->client, "", "reason", reason);
	}
}

void
priv_script_write_params(const char *prefix, struct client_lease *lease)
{
	struct interface_info *ip = ifi;
	u_int8_t dbuf[1500], *dp = NULL;
	int i;
	size_t len;
	char tbuf[128];

	script_set_env(ip->client, prefix, "ip_address",
	    piaddr(lease->address));

	if (ip->client->config->default_actions[DHO_SUBNET_MASK] ==
	    ACTION_SUPERSEDE) {
		dp = ip->client->config->defaults[DHO_SUBNET_MASK].data;
		len = ip->client->config->defaults[DHO_SUBNET_MASK].len;
	} else {
		dp = lease->options[DHO_SUBNET_MASK].data;
		len = lease->options[DHO_SUBNET_MASK].len;
	}
	if (len && (len < sizeof(lease->address.iabuf))) {
		struct iaddr netmask, subnet, broadcast;

		memcpy(netmask.iabuf, dp, len);
		netmask.len = len;
		subnet = subnet_number(lease->address, netmask);
		if (subnet.len) {
			script_set_env(ip->client, prefix, "network_number",
			    piaddr(subnet));
			if (!lease->options[DHO_BROADCAST_ADDRESS].len) {
				broadcast = broadcast_addr(subnet, netmask);
				if (broadcast.len)
					script_set_env(ip->client, prefix,
					    "broadcast_address",
					    piaddr(broadcast));
			}
		}
	}

	if (lease->filename)
		script_set_env(ip->client, prefix, "filename", lease->filename);
	if (lease->server_name)
		script_set_env(ip->client, prefix, "server_name",
		    lease->server_name);
	for (i = 0; i < 256; i++) {
		len = 0;

		if (ip->client->config->defaults[i].len) {
			if (lease->options[i].len) {
				switch (
				    ip->client->config->default_actions[i]) {
				case ACTION_DEFAULT:
					dp = lease->options[i].data;
					len = lease->options[i].len;
					break;
				case ACTION_SUPERSEDE:
supersede:
					dp = ip->client->
						config->defaults[i].data;
					len = ip->client->
						config->defaults[i].len;
					break;
				case ACTION_PREPEND:
					len = ip->client->
					    config->defaults[i].len +
					    lease->options[i].len;
					if (len >= sizeof(dbuf)) {
						warning("no space to %s %s",
						    "prepend option",
						    dhcp_options[i].name);
						goto supersede;
					}
					dp = dbuf;
					memcpy(dp,
						ip->client->
						config->defaults[i].data,
						ip->client->
						config->defaults[i].len);
					memcpy(dp + ip->client->
						config->defaults[i].len,
						lease->options[i].data,
						lease->options[i].len);
					dp[len] = '\0';
					break;
				case ACTION_APPEND:
					/*
					 * When we append, we assume that we're
					 * appending to text.  Some MS servers
					 * include a NUL byte at the end of
					 * the search string provided.
					 */
					len = ip->client->
					    config->defaults[i].len +
					    lease->options[i].len;
					if (len >= sizeof(dbuf)) {
						warning("no space to %s %s",
						    "append option",
						    dhcp_options[i].name);
						goto supersede;
					}
					memcpy(dbuf,
						lease->options[i].data,
						lease->options[i].len);
					for (dp = dbuf + lease->options[i].len;
					    dp > dbuf; dp--, len--)
						if (dp[-1] != '\0')
							break;
					memcpy(dp,
						ip->client->
						config->defaults[i].data,
						ip->client->
						config->defaults[i].len);
					dp = dbuf;
					dp[len] = '\0';
				}
			} else {
				dp = ip->client->
					config->defaults[i].data;
				len = ip->client->
					config->defaults[i].len;
			}
		} else if (lease->options[i].len) {
			len = lease->options[i].len;
			dp = lease->options[i].data;
		} else {
			len = 0;
		}
		if (len) {
			char name[256];

			if (dhcp_option_ev_name(name, sizeof(name),
			    &dhcp_options[i]))
				script_set_env(ip->client, prefix, name,
				    pretty_print_option(i, dp, len, 0, 0));
		}
	}
	snprintf(tbuf, sizeof(tbuf), "%d", (int)lease->expiry);
	script_set_env(ip->client, prefix, "expiry", tbuf);
}

void
script_write_params(const char *prefix, struct client_lease *lease)
{
	size_t		 fn_len = 0, sn_len = 0, pr_len = 0;
	struct imsg_hdr	 hdr;
	struct buf	*buf;
	int		 errs, i;

	if (lease->filename != NULL)
		fn_len = strlen(lease->filename);
	if (lease->server_name != NULL)
		sn_len = strlen(lease->server_name);
	if (prefix != NULL)
		pr_len = strlen(prefix);

	hdr.code = IMSG_SCRIPT_WRITE_PARAMS;
	hdr.len = sizeof(hdr) + sizeof(*lease) +
	    sizeof(fn_len) + fn_len + sizeof(sn_len) + sn_len +
	    sizeof(pr_len) + pr_len;

	for (i = 0; i < 256; i++) {
		hdr.len += sizeof(lease->options[i].len);
		hdr.len += lease->options[i].len;
	}

	scripttime = time(NULL);

	if ((buf = buf_open(hdr.len)) == NULL)
		error("buf_open: %m");

	errs = 0;
	errs += buf_add(buf, &hdr, sizeof(hdr));
	errs += buf_add(buf, lease, sizeof(*lease));
	errs += buf_add(buf, &fn_len, sizeof(fn_len));
	errs += buf_add(buf, lease->filename, fn_len);
	errs += buf_add(buf, &sn_len, sizeof(sn_len));
	errs += buf_add(buf, lease->server_name, sn_len);
	errs += buf_add(buf, &pr_len, sizeof(pr_len));
	errs += buf_add(buf, prefix, pr_len);

	for (i = 0; i < 256; i++) {
		errs += buf_add(buf, &lease->options[i].len,
		    sizeof(lease->options[i].len));
		errs += buf_add(buf, lease->options[i].data,
		    lease->options[i].len);
	}

	if (errs)
		error("buf_add: %m");

	if (buf_close(privfd, buf) == -1)
		error("buf_close: %m");
}

int
script_go(void)
{
	struct imsg_hdr	 hdr;
	struct buf	*buf;
	int		 ret;

	hdr.code = IMSG_SCRIPT_GO;
	hdr.len = sizeof(struct imsg_hdr);

	if ((buf = buf_open(hdr.len)) == NULL)
		error("buf_open: %m");

	if (buf_add(buf, &hdr, sizeof(hdr)))
		error("buf_add: %m");

	if (buf_close(privfd, buf) == -1)
		error("buf_close: %m");

	bzero(&hdr, sizeof(hdr));
	buf_read(privfd, &hdr, sizeof(hdr));
	if (hdr.code != IMSG_SCRIPT_GO_RET)
		error("unexpected msg type %u", hdr.code);
	if (hdr.len != sizeof(hdr) + sizeof(int))
		error("received corrupted message");
	buf_read(privfd, &ret, sizeof(ret));

	scripttime = time(NULL);

	return (ret);
}

int
priv_script_go(void)
{
	char *scriptName, *argv[2], **envp, *epp[3], reason[] = "REASON=NBI";
	static char client_path[] = CLIENT_PATH;
	struct interface_info *ip = ifi;
	int pid, wpid, wstatus;

	scripttime = time(NULL);

	if (ip) {
		scriptName = ip->client->config->script_name;
		envp = ip->client->scriptEnv;
	} else {
		scriptName = top_level_config.script_name;
		epp[0] = reason;
		epp[1] = client_path;
		epp[2] = NULL;
		envp = epp;
	}

	argv[0] = scriptName;
	argv[1] = NULL;

	pid = fork();
	if (pid < 0) {
		error("fork: %m");
		wstatus = 0;
	} else if (pid) {
		do {
			wpid = wait(&wstatus);
		} while (wpid != pid && wpid > 0);
		if (wpid < 0) {
			error("wait: %m");
			wstatus = 0;
		}
	} else {
		execve(scriptName, argv, envp);
		error("execve (%s, ...): %m", scriptName);
	}

	if (ip)
		script_flush_env(ip->client);

	return (WIFEXITED(wstatus) ?
	    WEXITSTATUS(wstatus) : 128 + WTERMSIG(wstatus));
}

void
script_set_env(struct client_state *client, const char *prefix,
    const char *name, const char *value)
{
	int i, namelen;
	size_t j;

	/* No `` or $() command substitution allowed in environment values! */
	for (j=0; j < strlen(value); j++)
		switch (value[j]) {
		case '`':
		case '$':
			warning("illegal character (%c) in value '%s'",
			    value[j], value);
			/* Ignore this option */
			return;
		}

	namelen = strlen(name);

	for (i = 0; client->scriptEnv[i]; i++)
		if (strncmp(client->scriptEnv[i], name, namelen) == 0 &&
		    client->scriptEnv[i][namelen] == '=')
			break;

	if (client->scriptEnv[i])
		/* Reuse the slot. */
		free(client->scriptEnv[i]);
	else {
		/* New variable.  Expand if necessary. */
		if (i >= client->scriptEnvsize - 1) {
			char **newscriptEnv;
			int newscriptEnvsize = client->scriptEnvsize + 50;

			newscriptEnv = realloc(client->scriptEnv,
			    newscriptEnvsize);
			if (newscriptEnv == NULL) {
				free(client->scriptEnv);
				client->scriptEnv = NULL;
				client->scriptEnvsize = 0;
				error("script_set_env: no memory for variable");
			}
			client->scriptEnv = newscriptEnv;
			client->scriptEnvsize = newscriptEnvsize;
		}
		/* need to set the NULL pointer at end of array beyond
		   the new slot. */
		client->scriptEnv[i + 1] = NULL;
	}
	/* Allocate space and format the variable in the appropriate slot. */
	client->scriptEnv[i] = malloc(strlen(prefix) + strlen(name) + 1 +
	    strlen(value) + 1);
	if (client->scriptEnv[i] == NULL)
		error("script_set_env: no memory for variable assignment");
	snprintf(client->scriptEnv[i], strlen(prefix) + strlen(name) +
	    1 + strlen(value) + 1, "%s%s=%s", prefix, name, value);
}

void
script_flush_env(struct client_state *client)
{
	int i;

	for (i = 0; client->scriptEnv[i]; i++) {
		free(client->scriptEnv[i]);
		client->scriptEnv[i] = NULL;
	}
	client->scriptEnvsize = 0;
}

int
dhcp_option_ev_name(char *buf, size_t buflen, struct option *option)
{
	size_t i;

	for (i = 0; option->name[i]; i++) {
		if (i + 1 == buflen)
			return 0;
		if (option->name[i] == '-')
			buf[i] = '_';
		else
			buf[i] = option->name[i];
	}

	buf[i] = 0;
	return 1;
}

void
go_daemon(void)
{
	static int state = 0;
	cap_rights_t rights;

	if (no_daemon || state)
		return;

	state = 1;

	/* Stop logging to stderr... */
	log_perror = 0;

	if (daemonfd(-1, nullfd) == -1)
		error("daemon");

	cap_rights_init(&rights);

	if (pidfile != NULL) {
		pidfile_write(pidfile);

		if (caph_rights_limit(pidfile_fileno(pidfile), &rights) < 0)
			error("can't limit pidfile descriptor: %m");
	}

	if (nullfd != -1) {
		close(nullfd);
		nullfd = -1;
	}

	if (caph_rights_limit(STDIN_FILENO, &rights) < 0)
		error("can't limit stdin: %m");
	cap_rights_init(&rights, CAP_WRITE);
	if (caph_rights_limit(STDOUT_FILENO, &rights) < 0)
		error("can't limit stdout: %m");
	if (caph_rights_limit(STDERR_FILENO, &rights) < 0)
		error("can't limit stderr: %m");
}

int
check_option(struct client_lease *l, int option)
{
	const char *opbuf;
	const char *sbuf;

	/* we use this, since this is what gets passed to dhclient-script */

	opbuf = pretty_print_option(option, l->options[option].data,
	    l->options[option].len, 0, 0);

	sbuf = option_as_string(option, l->options[option].data,
	    l->options[option].len);

	switch (option) {
	case DHO_SUBNET_MASK:
	case DHO_TIME_SERVERS:
	case DHO_NAME_SERVERS:
	case DHO_ROUTERS:
	case DHO_DOMAIN_NAME_SERVERS:
	case DHO_LOG_SERVERS:
	case DHO_COOKIE_SERVERS:
	case DHO_LPR_SERVERS:
	case DHO_IMPRESS_SERVERS:
	case DHO_RESOURCE_LOCATION_SERVERS:
	case DHO_SWAP_SERVER:
	case DHO_BROADCAST_ADDRESS:
	case DHO_NIS_SERVERS:
	case DHO_NTP_SERVERS:
	case DHO_NETBIOS_NAME_SERVERS:
	case DHO_NETBIOS_DD_SERVER:
	case DHO_FONT_SERVERS:
	case DHO_DHCP_SERVER_IDENTIFIER:
	case DHO_NISPLUS_SERVERS:
	case DHO_MOBILE_IP_HOME_AGENT:
	case DHO_SMTP_SERVER:
	case DHO_POP_SERVER:
	case DHO_NNTP_SERVER:
	case DHO_WWW_SERVER:
	case DHO_FINGER_SERVER:
	case DHO_IRC_SERVER:
	case DHO_STREETTALK_SERVER:
	case DHO_STREETTALK_DA_SERVER:
		if (!ipv4addrs(opbuf)) {
			warning("Invalid IP address in option: %s", opbuf);
			return (0);
		}
		return (1)  ;
	case DHO_HOST_NAME:
	case DHO_NIS_DOMAIN:
	case DHO_NISPLUS_DOMAIN:
	case DHO_TFTP_SERVER_NAME:
		if (!res_hnok(sbuf)) {
			warning("Bogus Host Name option %d: %s (%s)", option,
			    sbuf, opbuf);
			l->options[option].len = 0;
			free(l->options[option].data);
		}
		return (1);
	case DHO_DOMAIN_NAME:
	case DHO_DOMAIN_SEARCH:
		if (!res_hnok(sbuf)) {
			if (!check_search(sbuf)) {
				warning("Bogus domain search list %d: %s (%s)",
				    option, sbuf, opbuf);
				l->options[option].len = 0;
				free(l->options[option].data);
			}
		}
		return (1);
	case DHO_PAD:
	case DHO_TIME_OFFSET:
	case DHO_BOOT_SIZE:
	case DHO_MERIT_DUMP:
	case DHO_ROOT_PATH:
	case DHO_EXTENSIONS_PATH:
	case DHO_IP_FORWARDING:
	case DHO_NON_LOCAL_SOURCE_ROUTING:
	case DHO_POLICY_FILTER:
	case DHO_MAX_DGRAM_REASSEMBLY:
	case DHO_DEFAULT_IP_TTL:
	case DHO_PATH_MTU_AGING_TIMEOUT:
	case DHO_PATH_MTU_PLATEAU_TABLE:
	case DHO_INTERFACE_MTU:
	case DHO_ALL_SUBNETS_LOCAL:
	case DHO_PERFORM_MASK_DISCOVERY:
	case DHO_MASK_SUPPLIER:
	case DHO_ROUTER_DISCOVERY:
	case DHO_ROUTER_SOLICITATION_ADDRESS:
	case DHO_STATIC_ROUTES:
	case DHO_TRAILER_ENCAPSULATION:
	case DHO_ARP_CACHE_TIMEOUT:
	case DHO_IEEE802_3_ENCAPSULATION:
	case DHO_DEFAULT_TCP_TTL:
	case DHO_TCP_KEEPALIVE_INTERVAL:
	case DHO_TCP_KEEPALIVE_GARBAGE:
	case DHO_VENDOR_ENCAPSULATED_OPTIONS:
	case DHO_NETBIOS_NODE_TYPE:
	case DHO_NETBIOS_SCOPE:
	case DHO_X_DISPLAY_MANAGER:
	case DHO_DHCP_REQUESTED_ADDRESS:
	case DHO_DHCP_LEASE_TIME:
	case DHO_DHCP_OPTION_OVERLOAD:
	case DHO_DHCP_MESSAGE_TYPE:
	case DHO_DHCP_PARAMETER_REQUEST_LIST:
	case DHO_DHCP_MESSAGE:
	case DHO_DHCP_MAX_MESSAGE_SIZE:
	case DHO_DHCP_RENEWAL_TIME:
	case DHO_DHCP_REBINDING_TIME:
	case DHO_DHCP_CLASS_IDENTIFIER:
	case DHO_DHCP_CLIENT_IDENTIFIER:
	case DHO_BOOTFILE_NAME:
	case DHO_DHCP_USER_CLASS_ID:
	case DHO_URL:
	case DHO_SIP_SERVERS:
	case DHO_V_I_VENDOR_CLASS:
	case DHO_V_I_VENDOR_OPTS:
	case DHO_END:
		return (1);
	case DHO_CLASSLESS_ROUTES:
		return (check_classless_option(l->options[option].data,
		    l->options[option].len));
	default:
		warning("unknown dhcp option value 0x%x", option);
		return (unknown_ok);
	}
}

/* RFC 3442 The Classless Static Routes option checks */
int
check_classless_option(unsigned char *data, int len)
{
	int i = 0;
	unsigned char width;
	in_addr_t addr, mask;

	if (len < 5) {
		warning("Too small length: %d", len);
		return (0);
	}
	while(i < len) {
		width = data[i++];
		if (width == 0) {
			i += 4;
			continue;
		} else if (width < 9) {
			addr =  (in_addr_t)(data[i]	<< 24);
			i += 1;
		} else if (width < 17) {
			addr =  (in_addr_t)(data[i]	<< 24) +
				(in_addr_t)(data[i + 1]	<< 16);
			i += 2;
		} else if (width < 25) {
			addr =  (in_addr_t)(data[i]	<< 24) +
				(in_addr_t)(data[i + 1]	<< 16) +
				(in_addr_t)(data[i + 2]	<< 8);
			i += 3;
		} else if (width < 33) {
			addr =  (in_addr_t)(data[i]	<< 24) +
				(in_addr_t)(data[i + 1]	<< 16) +
				(in_addr_t)(data[i + 2]	<< 8)  +
				data[i + 3];
			i += 4;
		} else {
			warning("Incorrect subnet width: %d", width);
			return (0);
		}
		mask = (in_addr_t)(~0) << (32 - width);
		addr = ntohl(addr);
		mask = ntohl(mask);

		/*
		 * From RFC 3442:
		 * ... After deriving a subnet number and subnet mask
		 * from each destination descriptor, the DHCP client
		 * MUST zero any bits in the subnet number where the
		 * corresponding bit in the mask is zero...
		 */
		if ((addr & mask) != addr) {
			addr &= mask;
			data[i - 1] = (unsigned char)(
				(addr >> (((32 - width)/8)*8)) & 0xFF);
		}
		i += 4;
	}
	if (i > len) {
		warning("Incorrect data length: %d (must be %d)", len, i);
		return (0);
	}
	return (1);
}

int
res_hnok(const char *dn)
{
	int pch = PERIOD, ch = *dn++;

	while (ch != '\0') {
		int nch = *dn++;

		if (periodchar(ch)) {
			;
		} else if (periodchar(pch)) {
			if (!borderchar(ch))
				return (0);
		} else if (periodchar(nch) || nch == '\0') {
			if (!borderchar(ch))
				return (0);
		} else {
			if (!middlechar(ch))
				return (0);
		}
		pch = ch, ch = nch;
	}
	return (1);
}

int
check_search(const char *srch)
{
        int pch = PERIOD, ch = *srch++;
	int domains = 1;

	/* 256 char limit re resolv.conf(5) */
	if (strlen(srch) > 256)
		return (0);

	while (whitechar(ch))
		ch = *srch++;

        while (ch != '\0') {
                int nch = *srch++;

                if (periodchar(ch) || whitechar(ch)) {
                        ;
                } else if (periodchar(pch)) {
                        if (!borderchar(ch))
                                return (0);
                } else if (periodchar(nch) || nch == '\0') {
                        if (!borderchar(ch))
                                return (0);
                } else {
                        if (!middlechar(ch))
                                return (0);
                }
		if (!whitechar(ch)) {
			pch = ch;
		} else {
			while (whitechar(nch)) {
				nch = *srch++;
			}
			if (nch != '\0')
				domains++;
			pch = PERIOD;
		}
		ch = nch;
        }
	/* 6 domain limit re resolv.conf(5) */
	if (domains > 6)
		return (0);
        return (1);
}

/* Does buf consist only of dotted decimal ipv4 addrs?
 * return how many if so,
 * otherwise, return 0
 */
int
ipv4addrs(const char * buf)
{
	struct in_addr jnk;
	int count = 0;

	while (inet_aton(buf, &jnk) == 1){
		count++;
		while (periodchar(*buf) || digitchar(*buf))
			buf++;
		if (*buf == '\0')
			return (count);
		while (*buf ==  ' ')
			buf++;
	}
	return (0);
}


const char *
option_as_string(unsigned int code, unsigned char *data, int len)
{
	static char optbuf[32768]; /* XXX */
	char *op = optbuf;
	int opleft = sizeof(optbuf);
	unsigned char *dp = data;

	if (code > 255)
		error("option_as_string: bad code %d", code);

	for (; dp < data + len; dp++) {
		if (!isascii(*dp) || !isprint(*dp)) {
			if (dp + 1 != data + len || *dp != 0) {
				snprintf(op, opleft, "\\%03o", *dp);
				op += 4;
				opleft -= 4;
			}
		} else if (*dp == '"' || *dp == '\'' || *dp == '$' ||
		    *dp == '`' || *dp == '\\') {
			*op++ = '\\';
			*op++ = *dp;
			opleft -= 2;
		} else {
			*op++ = *dp;
			opleft--;
		}
	}
	if (opleft < 1)
		goto toobig;
	*op = 0;
	return optbuf;
toobig:
	warning("dhcp option too large");
	return "<error>";
}

int
fork_privchld(int fd, int fd2)
{
	struct pollfd pfd[1];
	int nfds;

	switch (fork()) {
	case -1:
		error("cannot fork");
	case 0:
		break;
	default:
		return (0);
	}

	setproctitle("%s [priv]", ifi->name);

	setsid();
	dup2(nullfd, STDIN_FILENO);
	dup2(nullfd, STDOUT_FILENO);
	dup2(nullfd, STDERR_FILENO);
	close(nullfd);
	close(fd2);
	close(ifi->rfdesc);
	ifi->rfdesc = -1;

	for (;;) {
		pfd[0].fd = fd;
		pfd[0].events = POLLIN;
		if ((nfds = poll(pfd, 1, INFTIM)) == -1)
			if (errno != EINTR)
				error("poll error");

		if (nfds == 0 || !(pfd[0].revents & POLLIN))
			continue;

		dispatch_imsg(ifi, fd);
	}
}