text: /*
   * 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/ioctl.h>
  
  #include <ctype.h>
  #include <poll.h>
  #include <pwd.h>
  #include <signal.h>
  #include <unistd.h>
  
  #include "dhcpd.h"
  #include "privsep.h"
  
  #define	CLIENT_PATH 		"PATH=/usr/bin:/usr/sbin:/bin:/sbin"
  #define DEFAULT_LEASE_TIME	43200	/* 12 hours... */
  #define TIME_MAX		2147483647
  #define POLL_FAILURES		10
  #define POLL_FAILURE_WAIT	1	/* Back off multiplier (seconds) */
  
  char *path_dhclient_conf = _PATH_DHCLIENT_CONF;
  char *path_dhclient_db = NULL;
  char *orig_ifname;
  
  int log_perror = 1;
  int privfd;
  int nullfd = -1;
  int no_daemon;
  int stayalive = 0;
  int unknown_ok = 1;
  int routefd = -1;
  pid_t monitor_pid;
  
  struct iaddr iaddr_broadcast = { 4, { 255, 255, 255, 255 } };
  struct in_addr inaddr_any;
  struct sockaddr_in sockaddr_broadcast;
  
  struct interface_info *ifi;
  struct client_state *client;
  struct client_config *config;
  
  int		findproto(char *, int);
  struct sockaddr	*get_ifa(char *, int);
  void		usage(void) __dead2;
  int		check_option(struct client_lease *l, int option);
  int		check_classless_option(unsigned char *data, int len);
  int		ipv4addrs(char * buf);
  int		res_hnok(const char *dn);
  char		*option_as_string(unsigned int code, unsigned char *data, int len);
  int		fork_privchld(int, int);
  void		get_ifname(char *, char *);
  static void	sig_handle(int sig);
  static int	killclient(int fd);
  
  time_t	scripttime;
  static FILE *leaseFile;
  
  int
  findproto(char *cp, int n)
  {
  	struct sockaddr *sa;
  	unsigned int 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;
  			}
  			RT_ADVANCE(cp, sa);
  		}
  	}
  	return (-1);
  }
  
  struct sockaddr *
  get_ifa(char *cp, int n)
  {
  	struct sockaddr *sa;
  	int 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);
  			RT_ADVANCE(cp, sa);
  		}
  
  	return (NULL);
  }
  struct iaddr defaddr = { .len = 4 }; /* NULL is for silence warnings */
  
  void
  routehandler(void)
  {
  	int linkstat;
  	char msg[2048];
  	struct rt_msghdr *rtm;
  	struct if_msghdr *ifm;
  	struct ifa_msghdr *ifam;
  	struct if_announcemsghdr *ifan;
  	struct client_lease *l;
  	struct sockaddr *sa;
  	struct iaddr a;
  	ssize_t n;
  	char *errmsg, buf[64];
  
  	do {
  		n = read(routefd, &msg, sizeof(msg));
  	} while (n == -1 && errno == EINTR);
  
  	rtm = (struct rt_msghdr *)msg;
  	if (n < sizeof(rtm->rtm_msglen) || n < rtm->rtm_msglen ||
  	    rtm->rtm_version != RTM_VERSION)
  		return;
  
  	switch (rtm->rtm_type) {
  	case RTM_NEWADDR:
  		ifam = (struct ifa_msghdr *)rtm;
  		if (ifam->ifam_index != ifi->index)
  			break;
  		if (findproto((char *)(ifam + 1), ifam->ifam_addrs) != AF_INET)
  			break;
  		sa = get_ifa((char *)(ifam + 1), ifam->ifam_addrs);
  		if (sa == NULL) {
  			errmsg = "sa == NULL";
  			goto die;
  		}
  
  		if ((a.len = sizeof(struct in_addr)) > sizeof(a.iabuf))
  			error("king bula sez: len mismatch");
  		memcpy(a.iabuf, &((struct sockaddr_in *)sa)->sin_addr, a.len);
  		if (addr_eq(a, defaddr))
  			break;
  
  		/* state_panic() can try unexpired existing leases */
  		if (client->active && addr_eq(a, client->active->address))
  			break;
  		for (l = client->leases; l != NULL; l = l->next)
  			if (addr_eq(a, l->address))
  				break;
  
  		if (l != NULL)
  			/* new addr is the one we set */
  			break;
  		snprintf(buf, sizeof(buf), "%s: %s",
  		    "new address not one we set", piaddr(a));
  		errmsg = buf;
  		goto die;
  	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;
  		/* XXX check addrs like RTM_NEWADDR instead of this? */
  		if (scripttime == 0 || time(NULL) < scripttime + 10)
  			break;
  		errmsg = "interface address deleted";
  		goto die;
  	case RTM_IFINFO:
  		ifm = (struct if_msghdr *)rtm;
  		if (ifm->ifm_index != ifi->index)
  			break;
  		if ((rtm->rtm_flags & RTF_UP) == 0) {
  			errmsg = "interface down";
  			goto die;
  		}
  
  		linkstat =
  		    LINK_STATE_IS_UP(ifm->ifm_data.ifi_link_state) ? 1 : 0;
  		if (linkstat != ifi->linkstat) {
  #ifdef DEBUG
  			debug("link state %s -> %s",
  			    ifi->linkstat ? "up" : "down",
  			    linkstat ? "up" : "down");
  #endif
  			ifi->linkstat = interface_status(ifi->name);
  			if (ifi->linkstat) {
  				client->state = S_REBOOTING;
  				state_reboot();
  			}
  		}
  		break;
  	case RTM_IFANNOUNCE:
  		ifan = (struct if_announcemsghdr *)rtm;
  		if (ifan->ifan_what == IFAN_DEPARTURE &&
  		    ifan->ifan_index == ifi->index) {
  			errmsg = "interface departure";
  			goto die;
  		}
  		break;
  	default:
  		break;
  	}
  	return;
  
  die:
  	script_init("FAIL");
  	script_go();
  	error("routehandler: %s", errmsg);
  }
  
  int
  main(int argc, char *argv[])
  {
  	int ch, fd;
  	int pipe_fd[2];
  	int quiet = 0;
  	int dokillclient = 0;
  	int i;
  	struct passwd *pw;
  
  	/* Initially, log errors to stderr as well as to syslogd. */
  	openlog(getprogname(), LOG_PID | LOG_NDELAY, DHCPD_LOG_FACILITY);
  	setlogmask(LOG_UPTO(LOG_INFO));
  
  	signal(SIGINT, sig_handle);
  	signal(SIGHUP, sig_handle);
  
  	while ((ch = getopt(argc, argv, "c:dl:quwx")) != -1) {
  		switch (ch) {
  		case 'c':
  			path_dhclient_conf = optarg;
  			break;
  		case 'd':
  			no_daemon = 1;
  			break;
  		case 'l':
  			path_dhclient_db = optarg;
  			break;
  		case 'q':
  			quiet = 1;
  			break;
  		case 'u':
  			unknown_ok = 0;
  			break;
  		case 'w':
  			stayalive = 1;
  			break;
  		case 'x':
  			dokillclient = 1;
  			break;
  		default:
  			usage();
  		}
  	}
  
  	argc -= optind;
  	argv += optind;
  
  	if (argc != 1)
  		usage();
  	orig_ifname = argv[0];
  
  	if (dokillclient) {
  		char buf[256];
  
  		snprintf(buf, sizeof(buf),
  			 "/var/run/dhclient.%s.pid", orig_ifname);
  		fd = open(buf, O_RDWR, 0644);
  		if (fd < 0 || killclient(fd)) {
  			fprintf(stderr,
  				"no dhclient running on %s\n",
  				orig_ifname);
  		} else {
  			fprintf(stderr,
  				"stopping dhclient on %s\n",
  				orig_ifname);
  		}
  		if (fd >= 0)
  			close(fd);
  		exit(1);
  	}
  
  	if ((nullfd = open(_PATH_DEVNULL, O_RDWR, 0)) == -1)
  		error("cannot open %s: %m", _PATH_DEVNULL);
  
  	/*
  	 * If asked to stay alive forever get our daemon going right now
  	 * Then set up to fork/monitor and refork on exit.
  	 *
  	 * When I say 'forever' I really mean it.  If there are configuration
  	 * problems or missing interfaces or whatever, dhclient will wait
  	 * 10 seconds and try again.
  	 */
  	if (stayalive) {
  		pid_t pid;
  		pid_t rpid;
  		int omask;
  
  		go_daemon();
  
  		for (;;) {
  			omask = sigblock(sigmask(SIGINT) | sigmask(SIGHUP));
  			pid = fork();
  			if (pid > 0)
  				monitor_pid = pid;
  			sigsetmask(omask);
  
  			if (pid == 0)	/* child falls out of loop */
  				break;
  			while (pid > 0) {
  				rpid = waitpid(pid, NULL, 0);
  				if (rpid == pid)
  					break;
  				if (rpid != EINTR)
  					break;
  			}
  			sleep(10);
  		}
  	}
  
  	ifi = calloc(1, sizeof(*ifi));
  	if (ifi == NULL)
  		error("ifi calloc");
  	client = calloc(1, sizeof(*client));
  	if (client == NULL)
  		error("client calloc");
  	config = calloc(1, sizeof(*config));
  	if (config == NULL)
  		error("config calloc");
  
  	get_ifname(ifi->name, argv[0]);
  
  	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();
  
  	memset(&sockaddr_broadcast, 0, sizeof(sockaddr_broadcast));
  	sockaddr_broadcast.sin_family = AF_INET;
  	sockaddr_broadcast.sin_port = htons(REMOTE_PORT);
  	sockaddr_broadcast.sin_addr.s_addr = INADDR_BROADCAST;
  	sockaddr_broadcast.sin_len = sizeof(sockaddr_broadcast);
  	inaddr_any.s_addr = INADDR_ANY;
  
  	read_client_conf();
  
  	if (interface_status(ifi->name) == 0) {
  		interface_link_forceup(ifi->name);
  		/* Give it up to 4 seconds of silent grace to find link */
  		i = -4;
  	} else {
  		i = 0;
  	}
  
  	while (!(ifi->linkstat = interface_status(ifi->name))) {
  		if (i == 0)
  			fprintf(stderr, "%s: no link ...", ifi->name);
  		else if (i > 0)
  			fprintf(stderr, ".");
  		fflush(stderr);
  		if (++i > config->link_timeout) {
  			fprintf(stderr, " sleeping\n");
  			goto dispatch;
  		}
  		sleep(1);
  	}
  	if (i > 0)
  		fprintf(stderr, " got link\n");
  
   dispatch:
  	if ((pw = getpwnam("_dhcp")) == NULL)
  		error("no such user: _dhcp");
  
  	if (pipe(pipe_fd) == -1)
  		error("pipe");
  
  	go_daemon();
  	fork_privchld(pipe_fd[0], pipe_fd[1]);
  
  	close(pipe_fd[0]);
  	privfd = pipe_fd[1];
  
  	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();
  	if ((leaseFile = fopen(path_dhclient_db, "w")) == NULL)
  		error("can't open %s: %m", path_dhclient_db);
  	rewrite_client_leases();
  	close(fd);
  
  	if ((routefd = socket(PF_ROUTE, SOCK_RAW, 0)) == -1)
  		error("socket(PF_ROUTE, SOCK_RAW): %m");
  
  	/* set up the interface */
  	discover_interface();
  
  	if (chroot(_PATH_VAREMPTY) == -1)
  		error("chroot");
  	if (chdir("/") == -1)
  		error("chdir(\"/\")");
  
  	if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1)
  		error("setresgid");
  	if (setgroups(1, &pw->pw_gid) == -1)
  		error("setgroups");
  	if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
  		error("setresuid");
  
  	endpwent();
  
  	setproctitle("%s", ifi->name);
  
  	if (ifi->linkstat) {
  		client->state = S_REBOOTING;
  		state_reboot();
  	}
  	dispatch();
  
  	/* not reached */
  	return (0);
  }
  
  void
  usage(void)
  {
  	fprintf(stderr, "usage: %s [-dqu] [-c file] [-l file] interface\n",
  	    getprogname());
  	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)
  {
  	/* Cancel all timeouts, since a link state change gets us here
  	   and can happen anytime. */
  	cancel_timeout();
  
  	/* If we don't remember an active lease, go straight to INIT. */
  	if (!client->active || client->active->is_bootp) {
  		client->state = S_INIT;
  		state_init();
  		return;
  	}
  
  	/* 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. */
  	client->xid = arc4random();
  
  	/* Make a DHCPREQUEST packet, and set appropriate per-interface
  	   flags. */
  	make_request(client->active);
  	client->destination = iaddr_broadcast;
  	client->first_sending = time(NULL);
  	client->interval = 0;
  
  	send_request();
  }
  
  /*
   * Called when a lease has completely expired and we've
   * been unable to renew it.
   */
  void
  state_init(void)
  {
  	/* Make a DHCPDISCOVER packet, and set appropriate per-interface
  	   flags. */
  	make_discover(client->active);
  	client->xid = client->packet.xid;
  	client->destination = iaddr_broadcast;
  	client->state = S_SELECTING;
  	client->first_sending = time(NULL);
  	client->interval = 0;
  
  	send_discover();
  }
  
  /*
   * 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)
  {
  	struct client_lease *lp, *next, *picked;
  	time_t cur_time;
  
  	/* Cancel state_selecting and send_discover timeouts, since either
  	   one could have got us here. */
  	cancel_timeout();
  
  	/* 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 = client->offered_leases; lp; lp = next) {
  		next = lp->next;
  
  		if (!picked) {
  			picked = lp;
  		} else {
  			make_decline(lp);
  			send_decline();
  			free_client_lease(lp);
  		}
  	}
  	client->offered_leases = NULL;
  
  	/* If we just tossed all the leases we were offered, go back
  	   to square one. */
  	if (!picked) {
  		client->state = S_INIT;
  		state_init();
  		return;
  	}
  	picked->next = NULL;
  
  	time(&cur_time);
  
  	/* If it was a BOOTREPLY, we can just take the address right now. */
  	if (!picked->options[DHO_DHCP_MESSAGE_TYPE].len) {
  		client->new = picked;
  
  		/* Make up some lease expiry times
  		   XXX these should be configurable. */
  		client->new->expiry = cur_time + 12000;
  		client->new->renewal += cur_time + 8000;
  		client->new->rebind += cur_time + 10000;
  
  		client->state = S_REQUESTING;
  
  		/* Bind to the address we received. */
  		bind_lease();
  		return;
  	}
  
  	/* Go to the REQUESTING state. */
  	client->destination = iaddr_broadcast;
  	client->state = S_REQUESTING;
  	client->first_sending = cur_time;
  	client->interval = 0;
  
  	/* Make a DHCPREQUEST packet from the lease we picked. */
  	make_request(picked);
  	client->xid = client->packet.xid;
  
  	/* Toss the lease we picked - we'll get it back in a DHCPACK. */
  	free_client_lease(picked);
  
  	send_request();
  }
  
  void
  dhcpack(struct iaddr client_addr, struct option_data *options)
  {
  	struct client_lease *lease;
  	time_t cur_time;
  
  
  	if (client->state != S_REBOOTING &&
  	    client->state != S_REQUESTING &&
  	    client->state != S_RENEWING &&
  	    client->state != S_REBINDING)
  		return;
  
  
  	lease = packet_to_lease(options);
  	if (!lease) {
  		note("packet_to_lease failed.");
  		return;
  	}
  
  	client->new = lease;
  
  	/* Stop resending DHCPREQUEST. */
  	cancel_timeout();
  
  	/* Figure out the lease time. */
  	if (client->new->options[DHO_DHCP_LEASE_TIME].data)
  		client->new->expiry =
  		    getULong(client->new->options[DHO_DHCP_LEASE_TIME].data);
  	else
  		client->new->expiry = DEFAULT_LEASE_TIME;
  	/* A number that looks negative here is really just very large,
  	   because the lease expiry offset is unsigned. */
  	if (client->new->expiry < 0)
  		client->new->expiry = TIME_MAX;
  	/* XXX should be fixed by resetting the client state */
  	if (client->new->expiry < 60)
  		client->new->expiry = 60;
  
  	/* Take the server-provided renewal time if there is one;
  	   otherwise figure it out according to the spec. */
  	if (client->new->options[DHO_DHCP_RENEWAL_TIME].len)
  		client->new->renewal =
  		    getULong(client->new->options[DHO_DHCP_RENEWAL_TIME].data);
  	else
  		client->new->renewal = client->new->expiry / 2;
  
  	/* Same deal with the rebind time. */
  	if (client->new->options[DHO_DHCP_REBINDING_TIME].len)
  		client->new->rebind =
  		    getULong(client->new->options[DHO_DHCP_REBINDING_TIME].data);
  	else
  		client->new->rebind = client->new->renewal +
  		    client->new->renewal / 2 + client->new->renewal / 4;
  
  	time(&cur_time);
  
  	client->new->expiry += cur_time;
  	/* Lease lengths can never be negative. */
  	if (client->new->expiry < cur_time)
  		client->new->expiry = TIME_MAX;
  	client->new->renewal += cur_time;
  	if (client->new->renewal < cur_time)
  		client->new->renewal = TIME_MAX;
  	client->new->rebind += cur_time;
  	if (client->new->rebind < cur_time)
  		client->new->rebind = TIME_MAX;
  
  	bind_lease();
  }
  
  void
  bind_lease(void)
  {
  	/* Run the client script with the new parameters. */
  	script_init((client->state == S_REQUESTING ? "BOUND" :
  	    (client->state == S_RENEWING ? "RENEW" :
  		(client->state == S_REBOOTING ? "REBOOT" : "REBIND"))));
  	if (client->active && client->state != S_REBOOTING)
  		script_write_params("old_", client->active);
  	script_write_params("new_", client->new);
  	script_go();
  
  	/* Replace the old active lease with the new one. */
  	if (client->active)
  		free_client_lease(client->active);
  	client->active = client->new;
  	client->new = NULL;
  
  	/* Write out new leases file. */
  	rewrite_client_leases();
  
  	/* Set timeout to start the renewal process. */
  	set_timeout(client->active->renewal, state_bound);
  
  	note("bound to %s -- renewal in %lld seconds.",
  	    piaddr(client->active->address),
  	    (long long)(client->active->renewal - time(NULL)));
  	client->state = S_BOUND;
  }
  
  /*
   * 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)
  {
  	/* T1 has expired. */
  	make_request(client->active);
  	client->xid = client->packet.xid;
  
  	if (client->active->options[DHO_DHCP_SERVER_IDENTIFIER].len == 4) {
  		memcpy(client->destination.iabuf,
  		    client->active->options[DHO_DHCP_SERVER_IDENTIFIER].data,
  		    4);
  		client->destination.len = 4;
  	} else
  		client->destination = iaddr_broadcast;
  
  	client->first_sending = time(NULL);
  	client->interval = 0;
  	client->state = S_RENEWING;
  
  	send_request();
  }
  
  void
  dhcpoffer(struct iaddr client_addr, struct option_data *options)
  {
  	struct client_lease *lease, *lp;
  	int i;
  	time_t stop_selecting;
  	char *name = options[DHO_DHCP_MESSAGE_TYPE].len ? "DHCPOFFER" :
  	    "BOOTREPLY";
  
  
  	if (client->state != S_SELECTING)
  		return;
  
  
  	/* If this lease doesn't supply the minimum required parameters,
  	   blow it off. */
  	for (i = 0; config->required_options[i]; i++) {
  		if (!options[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 = client->offered_leases;
  	    lease; lease = lease->next) {
  		if (lease->address.len == sizeof(client->packet.yiaddr) &&
  		    !memcmp(lease->address.iabuf,
  		    &client->packet.yiaddr, lease->address.len)) {
  #ifdef DEBUG
  			debug("%s already seen.", name);
  #endif
  			return;
  		}
  	}
  
  	lease = packet_to_lease(options);
  	if (!lease) {
  		note("packet_to_lease failed.");
  		return;
  	}
  
  	/*
  	 * Reject offers whose subnet is already configured on another
  	 * interface.
  	 */
  	if (subnet_exists(lease))
  		return;
  
  	/* If this lease was acquired through a BOOTREPLY, record that
  	   fact. */
  	if (!options[DHO_DHCP_MESSAGE_TYPE].len)
  		lease->is_bootp = 1;
  
  	/* Figure out when we're supposed to stop selecting. */
  	stop_selecting = client->first_sending + 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 (addr_eq(lease->address, client->requested_address)) {
  		lease->next = client->offered_leases;
  		client->offered_leases = lease;
  	} else {
  		/* Put the lease at the end of the list. */
  		lease->next = NULL;
  		if (!client->offered_leases)
  			client->offered_leases = lease;
  		else {
  			for (lp = client->offered_leases; lp->next;
  			    lp = lp->next)
  				;	/* nothing */
  			lp->next = lease;
  		}
  	}
  
  	/* If the selecting interval has expired, go immediately to
  	   state_selecting().  Otherwise, time out into
  	   state_selecting at the select interval. */
  	if (stop_selecting <= time(NULL))
  		state_selecting();
  	else {
  		set_timeout(stop_selecting, state_selecting);
  	}
  }
  
  /*
   * Allocate a client_lease structure and initialize it from the
   * parameters in the specified packet.
   */
  struct client_lease *
  packet_to_lease(struct option_data *options)
  {
  	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 (options[i].len) {
  			lease->options[i] = options[i];
  			options[i].data = NULL;
  			options[i].len = 0;
  			if (!check_option(lease, i)) {
  				warning("Invalid lease option - ignoring offer");
  				free_client_lease(lease);
  				return (NULL);
  			}
  		}
  	}
  
  	lease->address.len = sizeof(client->packet.yiaddr);
  	memcpy(lease->address.iabuf, &client->packet.yiaddr,
  	    lease->address.len);
  
  	/* If the server name was filled out, copy it. */
  	if ((!lease->options[DHO_DHCP_OPTION_OVERLOAD].len ||
  	    !(lease->options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 2)) &&
  	    client->packet.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, client->packet.sname,
  		    DHCP_SNAME_LEN);
  		lease->server_name[DHCP_SNAME_LEN] = '\0';
  		if (!res_hnok(lease->server_name)) {
  			warning("Bogus server name %s", lease->server_name);
  			free(lease->server_name);
  			lease->server_name = NULL;
  		}
  	}
  
  	/* Ditto for the filename. */
  	if ((!lease->options[DHO_DHCP_OPTION_OVERLOAD].len ||
  	    !(lease->options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 1)) &&
  	    client->packet.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, client->packet.file, DHCP_FILE_LEN);
  		lease->filename[DHCP_FILE_LEN] = '\0';
  	}
  	return lease;
  }
  
  void
  dhcpnak(struct iaddr client_addr, struct option_data *options)
  {
  
  	if (client->state != S_REBOOTING &&
  	    client->state != S_REQUESTING &&
  	    client->state != S_RENEWING &&
  	    client->state != S_REBINDING)
  		return;
  
  
  	if (!client->active) {
  		note("DHCPNAK with no active lease.");
  		return;
  	}
  
  	free_client_lease(client->active);
  	client->active = NULL;
  
  	/* Stop sending DHCPREQUEST packets... */
  	cancel_timeout();
  
  	client->state = S_INIT;
  	state_init();
  }
  
  /*
   * 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)
  {
  	time_t cur_time;
  	int interval, increase = 1;
  
  	time(&cur_time);
  
  	/* Figure out how long it's been since we started transmitting. */
  	interval = cur_time - 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 > config->timeout) {
  		state_panic();
  		return;
  	}
  
  	/*
  	 * 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 initial_interval; 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 (!client->interval)
  			client->interval = config->initial_interval;
  		else {
  			client->interval += (arc4random() >> 2) %
  			    (2 * client->interval);
  		}
  
  		/* Don't backoff past cutoff. */
  		if (client->interval > config->backoff_cutoff)
  			client->interval = ((config->backoff_cutoff / 2)
  				 + ((arc4random() >> 2) %
  				    config->backoff_cutoff));
  	} else if (!client->interval)
  		client->interval = config->initial_interval;
  
  	/* If the backoff would take us to the panic timeout, just use that
  	   as the interval. */
  	if (cur_time + client->interval >
  	    client->first_sending + config->timeout)
  		client->interval = (client->first_sending +
  			 config->timeout) - cur_time + 1;
  
  	/* Record the number of seconds since we started sending. */
  	if (interval < 65536)
  		client->packet.secs = htons(interval);
  	else
  		client->packet.secs = htons(65535);
  	client->secs = client->packet.secs;
  
  	note("DHCPDISCOVER on %s to %s port %d interval %ld",
  	    ifi->name, inet_ntoa(sockaddr_broadcast.sin_addr),
  	    ntohs(sockaddr_broadcast.sin_port), client->interval);
  
  	send_packet(inaddr_any, &sockaddr_broadcast, NULL);
  
  	set_timeout_interval(client->interval, send_discover);
  }
  
  /*
   * 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)
  {
  	struct client_lease *loop = client->active;
  	struct client_lease *lp;
  	time_t cur_time;
  
  	note("No DHCPOFFERS received.");
  
  	/* We may not have an active lease, but we may have some
  	   predefined leases that we can try. */
  	if (!client->active && client->leases)
  		goto activate_next;
  
  	/* Run through the list of leases and see if one can be used. */
  	time(&cur_time);
  	while (client->active) {
  		if (client->active->expiry > cur_time) {
  			note("Trying recorded lease %s",
  			    piaddr(client->active->address));
  			/* Run the client script with the existing
  			   parameters. */
  			script_init("TIMEOUT");
  			script_write_params("new_", client->active);
  
  			/* 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 < client->active->renewal) {
  					client->state = S_BOUND;
  					note("bound: renewal in %lld seconds.",
  					    (long long)(client->active->renewal
  					    - cur_time));
  					set_timeout(client->active->renewal,
  					    state_bound);
  				} else {
  					client->state = S_BOUND;
  					note("bound: immediate renewal.");
  					state_bound();
  				}
  				return;
  			}
  		}
  
  		/* If there are no other leases, give up. */
  		if (!client->leases) {
  			client->leases = client->active;
  			client->active = NULL;
  			break;
  		}
  
  activate_next:
  		/* Otherwise, put the active lease at the end of the
  		   lease list, and try another lease.. */
  		for (lp = client->leases; lp->next; lp = lp->next)
  			;
  		lp->next = client->active;
  		if (lp->next)
  			lp->next->next = NULL;
  		client->active = client->leases;
  		client->leases = 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 (client->active == loop)
  			break;
  		else if (!loop)
  			loop = 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.");
  	script_init("FAIL");
  	script_go();
  	client->state = S_INIT;
  	set_timeout_interval(config->retry_interval, state_init);
  }
  
  void
  send_request(void)
  {
  	struct sockaddr_in destination;
  	struct in_addr from;
  	time_t cur_time;
  	int interval;
  
  	time(&cur_time);
  
  	/* Figure out how long it's been since we started transmitting. */
  	interval = (int)(cur_time - 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 ((client->state == S_REBOOTING ||
  	    client->state == S_REQUESTING) &&
  	    interval > config->reboot_timeout) {
  		client->state = S_INIT;
  		cancel_timeout();
  		state_init();
  		return;
  	}
  
  	/* If the lease has expired, relinquish the address and go back
  	   to the INIT state. */
  	if (client->state != S_REQUESTING &&
  	    cur_time > client->active->expiry) {
  		/* Run the client script with the new parameters. */
  		script_init("EXPIRE");
  		script_write_params("old_", client->active);
  		script_go();
  
  		client->state = S_INIT;
  		state_init();
  		return;
  	}
  
  	/* Do the exponential backoff... */
  	if (!client->interval)
  		client->interval = config->initial_interval;
  	else
  		client->interval += ((arc4random() >> 2) %
  		    (2 * client->interval));
  
  	/* Don't backoff past cutoff. */
  	if (client->interval > config->backoff_cutoff)
  		client->interval = ((config->backoff_cutoff / 2) +
  		    ((arc4random() >> 2) % client->interval));
  
  	/* If the backoff would take us to the expiry time, just set the
  	   timeout to the expiry time. */
  	if (client->state != S_REQUESTING && cur_time + client->interval >
  	    client->active->expiry)
  		client->interval = 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. */
  	memset(&destination, 0, sizeof(destination));
  	if (client->state == S_REQUESTING ||
  	    client->state == S_REBOOTING ||
  	    cur_time > client->active->rebind)
  		destination.sin_addr.s_addr = INADDR_BROADCAST;
  	else
  		memcpy(&destination.sin_addr.s_addr, client->destination.iabuf,
  		    sizeof(destination.sin_addr.s_addr));
  	destination.sin_port = htons(REMOTE_PORT);
  	destination.sin_family = AF_INET;
  	destination.sin_len = sizeof(destination);
  
  	if (client->state != S_REQUESTING)
  		memcpy(&from, client->active->address.iabuf, sizeof(from));
  	else
  		from.s_addr = INADDR_ANY;
  
  	/* Record the number of seconds since we started sending. */
  	if (client->state == S_REQUESTING)
  		client->packet.secs = client->secs;
  	else {
  		if (interval < 65536)
  			client->packet.secs = htons(interval);
  		else
  			client->packet.secs = htons(65535);
  	}
  
  	note("DHCPREQUEST on %s to %s port %d", ifi->name,
  	    inet_ntoa(destination.sin_addr), ntohs(destination.sin_port));
  
  	send_packet(from, &destination, NULL);
  
  	set_timeout_interval(client->interval, send_request);
  }
  
  void
  send_decline(void)
  {
  	note("DHCPDECLINE on %s to %s port %d", ifi->name,
  	    inet_ntoa(sockaddr_broadcast.sin_addr),
  	    ntohs(sockaddr_broadcast.sin_port));
  
  	send_packet(inaddr_any, &sockaddr_broadcast, NULL);
  }
  
  void
  make_discover(struct client_lease *lease)
  {
  	unsigned char discover = DHCPDISCOVER;
  	struct option_data options[256];
  	int i;
  
  	memset(options, 0, sizeof(options));
  	memset(&client->packet, 0, sizeof(client->packet));
  
  	/* Set DHCP_MESSAGE_TYPE to DHCPDISCOVER */
  	i = DHO_DHCP_MESSAGE_TYPE;
  	options[i].data = &discover;
  	options[i].len = sizeof(discover);
  
  	/* Request the options we want */
  	i  = DHO_DHCP_PARAMETER_REQUEST_LIST;
  	options[i].data = config->requested_options;
  	options[i].len = config->requested_option_count;
  
  	/* If we had an address, try to get it again. */
  	if (lease) {
  		client->requested_address = lease->address;
  		i = DHO_DHCP_REQUESTED_ADDRESS;
  		options[i].data = lease->address.iabuf;
  		options[i].len = lease->address.len;
  	} else
  		client->requested_address.len = 0;
  
  	/* Send any options requested in the config file. */
  	for (i = 0; i < 256; i++)
  		if (!options[i].data &&
  		    config->send_options[i].data) {
  			options[i].data = config->send_options[i].data;
  			options[i].len = config->send_options[i].len;
  		}
  
  	/* Set up the option buffer to fit in a minimal UDP packet. */
  	i = cons_options(options);
  	if (i == -1 || client->packet.options[i] != DHO_END)
  		error("options do not fit in DHCPDISCOVER packet.");
  	client->packet_length = DHCP_FIXED_NON_UDP+i+1;
  	if (client->packet_length < BOOTP_MIN_LEN)
  		client->packet_length = BOOTP_MIN_LEN;
  
  	client->packet.op = BOOTREQUEST;
  	client->packet.htype = ifi->hw_address.htype;
  	client->packet.hlen = ifi->hw_address.hlen;
  	client->packet.hops = 0;
  	client->packet.xid = arc4random();
  	client->packet.secs = 0; /* filled in by send_discover. */
  	client->packet.flags = 0;
  
  	memset(&client->packet.ciaddr, 0, sizeof(client->packet.ciaddr));
  	memset(&client->packet.yiaddr, 0, sizeof(client->packet.yiaddr));
  	memset(&client->packet.siaddr, 0, sizeof(client->packet.siaddr));
  	memset(&client->packet.giaddr, 0, sizeof(client->packet.giaddr));
  	memcpy(client->packet.chaddr, ifi->hw_address.haddr,
  	    ifi->hw_address.hlen);
  }
  
  void
  make_request(struct client_lease * lease)
  {
  	unsigned char request = DHCPREQUEST;
  	struct option_data options[256];
  	int i;
  
  	memset(options, 0, sizeof(options));
  	memset(&client->packet, 0, sizeof(client->packet));
  
  	/* Set DHCP_MESSAGE_TYPE to DHCPREQUEST */
  	i = DHO_DHCP_MESSAGE_TYPE;
  	options[i].data = &request;
  	options[i].len = sizeof(request);
  
  	/* Request the options we want */
  	i = DHO_DHCP_PARAMETER_REQUEST_LIST;
  	options[i].data = config->requested_options;
  	options[i].len = config->requested_option_count;
  
  	/* If we are requesting an address that hasn't yet been assigned
  	   to us, use the DHCP Requested Address option. */
  	if (client->state == S_REQUESTING) {
  		/* Send back the server identifier... */
  		i = DHO_DHCP_SERVER_IDENTIFIER;
  		options[i].data = lease->options[i].data;
  		options[i].len = lease->options[i].len;
  	}
  	if (client->state == S_REQUESTING ||
  	    client->state == S_REBOOTING) {
  		client->requested_address = lease->address;
  		i = DHO_DHCP_REQUESTED_ADDRESS;
  		options[i].data = lease->address.iabuf;
  		options[i].len = lease->address.len;
  	} else
  		client->requested_address.len = 0;
  
  	/* Send any options requested in the config file. */
  	for (i = 0; i < 256; i++)
  		if (!options[i].data && config->send_options[i].data) {
  			options[i].data = config->send_options[i].data;
  			options[i].len = config->send_options[i].len;
  		}
  
  	/* Set up the option buffer to fit in a minimal UDP packet. */
  	i = cons_options(options);
  	if (i == -1 || client->packet.options[i] != DHO_END)
  		error("options do not fit in DHCPREQUEST packet.");
  	client->packet_length = DHCP_FIXED_NON_UDP+i+1;
  	if (client->packet_length < BOOTP_MIN_LEN)
  		client->packet_length = BOOTP_MIN_LEN;
  
  	client->packet.op = BOOTREQUEST;
  	client->packet.htype = ifi->hw_address.htype;
  	client->packet.hlen = ifi->hw_address.hlen;
  	client->packet.hops = 0;
  	client->packet.xid = client->xid;
  	client->packet.secs = 0; /* Filled in by send_request. */
  	client->packet.flags = 0;
  
  	/* If we own the address we're requesting, put it in ciaddr;
  	   otherwise set ciaddr to zero. */
  	if (client->state == S_BOUND ||
  	    client->state == S_RENEWING ||
  	    client->state == S_REBINDING) {
  		memcpy(&client->packet.ciaddr,
  		    lease->address.iabuf, lease->address.len);
  	} else {
  		memset(&client->packet.ciaddr, 0,
  		    sizeof(client->packet.ciaddr));
  	}
  
  	memset(&client->packet.yiaddr, 0, sizeof(client->packet.yiaddr));
  	memset(&client->packet.siaddr, 0, sizeof(client->packet.siaddr));
  	memset(&client->packet.giaddr, 0, sizeof(client->packet.giaddr));
  	memcpy(client->packet.chaddr, ifi->hw_address.haddr,
  	    ifi->hw_address.hlen);
  }
  
  void
  make_decline(struct client_lease *lease)
  {
  	struct option_data options[256];
  	unsigned char decline = DHCPDECLINE;
  	int i;
  
  	memset(options, 0, sizeof(options));
  	memset(&client->packet, 0, sizeof(client->packet));
  
  	/* Set DHCP_MESSAGE_TYPE to DHCPDECLINE */
  	i = DHO_DHCP_MESSAGE_TYPE;
  	options[i].data = &decline;
  	options[i].len = sizeof(decline);
  
  	/* Send back the server identifier... */
  	i = DHO_DHCP_SERVER_IDENTIFIER;
  	options[i].data = lease->options[i].data;
  	options[i].len = lease->options[i].len;
  
  	/* Send back the address we're declining. */
  	i = DHO_DHCP_REQUESTED_ADDRESS;
  	options[i].data = lease->address.iabuf;
  	options[i].len = lease->address.len;
  
  	/* Send the uid if the user supplied one. */
  	i = DHO_DHCP_CLIENT_IDENTIFIER;
  	if (config->send_options[i].len) {
  		options[i].data = config->send_options[i].data;
  		options[i].len = config->send_options[i].len;
  	}
  
  	/* Set up the option buffer to fit in a minimal UDP packet. */
  	i = cons_options(options);
  	if (i == -1 || client->packet.options[i] != DHO_END)
  		error("options do not fit in DHCPDECLINE packet.");
  	client->packet_length = DHCP_FIXED_NON_UDP+i+1;
  	if (client->packet_length < BOOTP_MIN_LEN)
  		client->packet_length = BOOTP_MIN_LEN;
  
  	client->packet.op = BOOTREQUEST;
  	client->packet.htype = ifi->hw_address.htype;
  	client->packet.hlen = ifi->hw_address.hlen;
  	client->packet.hops = 0;
  	client->packet.xid = client->xid;
  	client->packet.secs = 0; /* Filled in by send_request. */
  	client->packet.flags = 0;
  
  	/* ciaddr must always be zero. */
  	memset(&client->packet.ciaddr, 0, sizeof(client->packet.ciaddr));
  	memset(&client->packet.yiaddr, 0, sizeof(client->packet.yiaddr));
  	memset(&client->packet.siaddr, 0, sizeof(client->packet.siaddr));
  	memset(&client->packet.giaddr, 0, sizeof(client->packet.giaddr));
  	memcpy(client->packet.chaddr, ifi->hw_address.haddr,
  	    ifi->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);
  }
  
  void
  rewrite_client_leases(void)
  {
  	struct client_lease *lp;
  
  	if (!leaseFile)	/* XXX */
  		error("lease file not open");
  
  	fflush(leaseFile);
  	rewind(leaseFile);
  
  	for (lp = client->leases; lp; lp = lp->next) {
  		if (client->active && addr_eq(lp->address,
  			client->active->address))
  			continue;
  		write_client_lease(lp);
  	}
  
  	if (client->active)
  		write_client_lease(client->active);
  
  	fflush(leaseFile);
  	ftruncate(fileno(leaseFile), ftello(leaseFile));
  	fsync(fileno(leaseFile));
  }
  
  void
  write_client_lease(struct client_lease *lease)
  {
  	struct tm *t;
  	int i;
  
  	/* 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 */
  		error("lease file not open");
  
  	fprintf(leaseFile, "lease {\n");
  	if (lease->is_bootp)
  		fprintf(leaseFile, "  bootp;\n");
  	fprintf(leaseFile, "  interface \"%s\";\n", ifi->name);
  	fprintf(leaseFile, "  fixed-address %s;\n", piaddr(lease->address));
  	if (lease->filename)
  		fprintf(leaseFile, "  filename \"%s\";\n", lease->filename);
  	if (lease->server_name)
  		fprintf(leaseFile, "  server-name \"%s\";\n",
  		    lease->server_name);
  	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], 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(char *reason)
  {
  	size_t		 len;
  	struct imsg_hdr	 hdr;
  	struct buf	*buf;
  
  	hdr.code = IMSG_SCRIPT_INIT;
  	hdr.len = sizeof(struct imsg_hdr) + sizeof(size_t) + strlen(reason);
  	buf = buf_open(hdr.len);
  
  	buf_add(buf, &hdr, sizeof(hdr));
  	len = strlen(reason);
  	buf_add(buf, &len, sizeof(len));
  	buf_add(buf, reason, len);
  
  	buf_close(privfd, buf);
  }
  
  void
  priv_script_init(char *reason)
  {
  	client->scriptEnvsize = 100;
  	if (client->scriptEnv == NULL)
  		client->scriptEnv =
  		    calloc(client->scriptEnvsize, sizeof(char *));
  	if (client->scriptEnv == NULL)
  		error("script_init: no memory for environment");
  
  	client->scriptEnv[0] = strdup(CLIENT_PATH);
  	if (client->scriptEnv[0] == NULL)
  		error("script_init: no memory for environment");
  
  	client->scriptEnv[1] = NULL;
  
  	script_set_env("", "interface", ifi->name);
  
  	script_set_env("", "reason", reason);
  }
  
  void
  priv_script_write_params(char *prefix, struct client_lease *lease)
  {
  	char buf[256];
  	struct option_data o;
  	int i;
  
  	script_set_env(prefix, "ip_address", piaddr(lease->address));
  
  	if (lease->options[DHO_SUBNET_MASK].len &&
  	    (lease->options[DHO_SUBNET_MASK].len <
  	    sizeof(lease->address.iabuf))) {
  		struct iaddr netmask, subnet, broadcast;
  
  		memcpy(netmask.iabuf, lease->options[DHO_SUBNET_MASK].data,
  		    lease->options[DHO_SUBNET_MASK].len);
  		netmask.len = lease->options[DHO_SUBNET_MASK].len;
  
  		subnet = subnet_number(lease->address, netmask);
  		if (subnet.len) {
  			script_set_env(prefix, "network_number",
  			    piaddr(subnet));
  			if (!lease->options[DHO_BROADCAST_ADDRESS].len) {
  				broadcast = broadcast_addr(subnet, netmask);
  				if (broadcast.len)
  					script_set_env(prefix,
  					    "broadcast_address",
  					    piaddr(broadcast));
  			}
  		}
  	}
  
  	if (lease->filename)
  		script_set_env(prefix, "filename", lease->filename);
  	if (lease->server_name)
  		script_set_env(prefix, "server_name",
  		    lease->server_name);
  
  	for (i = 0; i < 256; i++) {
  		if (!dhcp_option_ev_name(buf, sizeof(buf), &dhcp_options[i]))
  			continue;
  
  		switch (config->default_actions[i]) {
  		case ACTION_IGNORE:
  			 break;
  
  		case ACTION_DEFAULT:
  			if (lease->options[i].len)
  				script_set_env(prefix, buf,
  				    pretty_print_option(i, &lease->options[i],
  					0));
  			else if (config->defaults[i].len)
  				script_set_env(prefix, buf,
  				    pretty_print_option(i, &config->defaults[i],
  					0));
  			break;
  
  		case ACTION_SUPERSEDE:
  			if (config->defaults[i].len)
  				script_set_env(prefix, buf,
  				    pretty_print_option(i, &config->defaults[i],
  					0));
  			break;
  
  		case ACTION_PREPEND:
  			o.len = config->defaults[i].len + lease->options[i].len;
  			if (o.len > 0) {
  				o.data = calloc(1, o.len);
  				if (o.data == NULL)
  					error("no space to prepend '%s' to %s",
  					    config->defaults[i].data,
  					    dhcp_options[i].name);
  				memcpy(o.data, config->defaults[i].data,
  				    config->defaults[i].len);
  				memcpy(o.data + config->defaults[i].len,
  				    lease->options[i].data,
  				    lease->options[i].len);
  				script_set_env(prefix, buf,
  				    pretty_print_option(i, &o, 0));
  				free(o.data);
  			}
  			break;
  
  		case ACTION_APPEND:
  			o.len = config->defaults[i].len + lease->options[i].len;
  			if (o.len > 0) {
  				o.data = calloc(1, o.len);
  				if (o.data == NULL)
  					error("no space to append '%s' to %s",
  					    config->defaults[i].data,
  					    dhcp_options[i].name);
  				memcpy(o.data, lease->options[i].data,
  				    lease->options[i].len);
  				memcpy(o.data + lease->options[i].len,
  				    config->defaults[i].data,
  				    config->defaults[i].len);
  				script_set_env(prefix, buf,
  				    pretty_print_option(i, &o, 0));
  				free(o.data);
  			}
  			break;
  		}
  	}
  
  	snprintf(buf, sizeof(buf), "%d", (int)lease->expiry);
  	script_set_env(prefix, "expiry", buf);
  }
  
  void
  script_write_params(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		 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(struct client_lease) +
  	    sizeof(size_t) + fn_len + sizeof(size_t) + sn_len +
  	    sizeof(size_t) + pr_len;
  
  	for (i = 0; i < 256; i++)
  		hdr.len += sizeof(int) + lease->options[i].len;
  
  	scripttime = time(NULL);
  
  	buf = buf_open(hdr.len);
  
  	buf_add(buf, &hdr, sizeof(hdr));
  	buf_add(buf, lease, sizeof(struct client_lease));
  	buf_add(buf, &fn_len, sizeof(fn_len));
  	buf_add(buf, lease->filename, fn_len);
  	buf_add(buf, &sn_len, sizeof(sn_len));
  	buf_add(buf, lease->server_name, sn_len);
  	buf_add(buf, &pr_len, sizeof(pr_len));
  	buf_add(buf, prefix, pr_len);
  
  	for (i = 0; i < 256; i++) {
  		buf_add(buf, &lease->options[i].len,
  		    sizeof(lease->options[i].len));
  		buf_add(buf, lease->options[i].data,
  		    lease->options[i].len);
  	}
  
  	buf_close(privfd, buf);
  }
  
  int
  script_go(void)
  {
  	struct imsg_hdr	 hdr;
  	struct buf	*buf;
  	int		 ret;
  
  	scripttime = time(NULL);
  
  	hdr.code = IMSG_SCRIPT_GO;
  	hdr.len = sizeof(struct imsg_hdr);
  
  	buf = buf_open(hdr.len);
  
  	buf_add(buf, &hdr, sizeof(hdr));
  	buf_close(privfd, buf);
  
  	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));
  
  	return (ret);
  }
  
  int
  priv_script_go(void)
  {
  	char *scriptName, *argv[2], **envp;
  	int pid, wpid, wstatus;
  
  	scripttime = time(NULL);
  
  	scriptName = config->script_name;
  	envp = client->scriptEnv;
  
  	argv[0] = scriptName;
  	argv[1] = NULL;
  
  	pid = fork();
  	if (pid < 0) {
  		error("fork: %m");
  	} else if (pid) {
  		do {
  			wpid = wait(&wstatus);
  		} while (wpid != pid && wpid > 0);
  		if (wpid < 0) {
  			error("wait: %m");
  		}
  	} else {
  		execve(scriptName, argv, envp);
  		error("execve (%s, ...): %m", scriptName);
  	}
  
  	script_flush_env();
  
  	return (WEXITSTATUS(wstatus));
  }
  
  void
  script_set_env(const char *prefix, const char *name, const char *value)
  {
  	int i, j, namelen;
  
  	/* 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(void)
  {
  	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, const 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)
  {
  	char buf[256];
  	int fd;
  
  	/*
  	 * Only once
  	 */
  	if (no_daemon == 2)
  		return;
  
  	/*
  	 * Setup pidfile, kill any dhclient already running for this
  	 * interface.
  	 */
  	snprintf(buf, sizeof(buf), "/var/run/dhclient.%s.pid", orig_ifname);
  	fd = open(buf, O_RDWR|O_CREAT, 0644);
  	if (fd >= 0) {
  		if (killclient(fd)) {
  			fprintf(stderr,
  				"starting dhclient on %s\n",
  				orig_ifname);
  		} else {
  			fprintf(stderr,
  				"restarting dhclient on %s\n",
  				orig_ifname);
  		}
  	}
  
  	/*
  	 * Daemonize if requested
  	 */
  	if (no_daemon == 0) {
  		/* Stop logging to stderr... */
  		log_perror = 0;
  
  		if (daemon(1, 0) == -1)
  			error("daemon");
  
  		/* we are chrooted, daemon(3) fails to open /dev/null */
  		if (nullfd != -1) {
  			dup2(nullfd, STDIN_FILENO);
  			dup2(nullfd, STDOUT_FILENO);
  			dup2(nullfd, STDERR_FILENO);
  			close(nullfd);
  			nullfd = -1;
  		}
  	}
  
  	/*
  	 * No further daemonizations, write out pid file and lock.
  	 */
  	no_daemon = 2;
  	if (fd >= 0) {
  		lseek(fd, 0L, SEEK_SET);
  		ftruncate(fd, 0);
  		snprintf(buf, sizeof(buf), "%ld\n", (long)getpid());
  		write(fd, buf, strlen(buf));
  		flock(fd, LOCK_EX);
  		/* leave descriptor open and locked */
  	}
  }
  
  int
  check_option(struct client_lease *l, int option)
  {
  	char *opbuf;
  	char *sbuf;
  
  	/* we use this, since this is what gets passed to dhclient-script */
  
  	opbuf = pretty_print_option(option, &l->options[option], 0);
  
  	sbuf = option_as_string(option, l->options[option].data,
  	    l->options[option].len);
  
  	switch (option) {
  	case DHO_SUBNET_MASK:
  	case DHO_SWAP_SERVER:
  	case DHO_BROADCAST_ADDRESS:
  	case DHO_DHCP_SERVER_IDENTIFIER:
  	case DHO_ROUTER_SOLICITATION_ADDRESS:
  	case DHO_DHCP_REQUESTED_ADDRESS:
  		if (ipv4addrs(opbuf) == 0) {
  			warning("Invalid IP address in option %s: %s",
  			    dhcp_options[option].name, opbuf);
  			return (0);
  		}
  		if (l->options[option].len != 4) { /* RFC 2132 */
  			warning("warning: Only 1 IP address allowed in "
  			    "%s option; length %d, must be 4",
  			    dhcp_options[option].name,
  			    l->options[option].len);
  			l->options[option].len = 4;
  		}
  		return (1);
  	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_NIS_SERVERS:
  	case DHO_NTP_SERVERS:
  	case DHO_NETBIOS_NAME_SERVERS:
  	case DHO_NETBIOS_DD_SERVER:
  	case DHO_FONT_SERVERS:
  		if (ipv4addrs(opbuf) == 0) {
  			warning("Invalid IP address in option %s: %s",
  			    dhcp_options[option].name, opbuf);
  			return (0);
  		}
  		return (1);
  	case DHO_HOST_NAME:
  	case DHO_DOMAIN_NAME:
  	case DHO_NIS_DOMAIN:
  		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_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_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_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_DHCP_USER_CLASS_ID:
  	case DHO_TFTP_SERVER:
  	case DHO_END:
  		return (1);
  	case DHO_CLASSLESS_ROUTES:
  		return (check_classless_option(l->options[option].data,
  					       l->options[option].len));
  	default:
  		if (!unknown_ok)
  			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 *name)
  {
  	const char *dn = name;
  	int pch = '.', ch = *dn++;
  	int warn = 0;
  
  	while (ch != '\0') {
  		int nch = *dn++;
  
  		if (ch == '.') {
  			;
  		} else if (pch == '.' || nch == '.' || nch == '\0') {
  			if (!isalnum(ch))
  				return (0);
  		} else if (!isalnum(ch) && ch != '-' && ch != '_')
  				return (0);
  		else if (ch == '_' && warn == 0) {
  			warning("warning: hostname %s contains an "
  			    "underscore which violates RFC 952", name);
  			warn++;
  		}
  		pch = ch, ch = nch;
  	}
  	return (1);
  }
  
  /* Does buf consist only of dotted decimal ipv4 addrs?
   * return how many if so,
   * otherwise, return 0
   */
  int
  ipv4addrs(char * buf)
  {
  	struct in_addr jnk;
  	int count = 0;
  
  	while (inet_aton(buf, &jnk) == 1){
  		count++;
  		while (*buf == '.' || isdigit(*buf))
  			buf++;
  		if (*buf == '\0')
  			return (count);
  		while (*buf ==  ' ')
  			buf++;
  	}
  	return (0);
  }
  
  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) {
  				size_t oplen;
  				snprintf(op, opleft, "\\%03o", *dp);
  				oplen = strlen(op);
  				op += oplen;
  				opleft -= oplen;
  			}
  		} 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, pfail = 0;
  	pid_t pid;
  	int omask;
  
  	omask = sigblock(sigmask(SIGINT)|sigmask(SIGHUP));
  	pid = fork();
  	if (pid > 0)
  		monitor_pid = pid;
  	sigsetmask(omask);
  
  	switch (pid) {
  	case -1:
  		error("cannot fork");
  		break;
  	case 0:
  		break;
  	default:
  		return (0);
  	}
  
  	if (chdir("/") == -1)
  		error("chdir(\"/\")");
  
  	setproctitle("%s [priv]", ifi->name);
  
  	dup2(nullfd, STDIN_FILENO);
  	dup2(nullfd, STDOUT_FILENO);
  	dup2(nullfd, STDERR_FILENO);
  	close(nullfd);
  	close(fd2);
  
  	for (;;) {
  		pfd[0].fd = fd;
  		pfd[0].events = POLLIN;
  		if ((nfds = poll(pfd, 1, INFTIM)) == -1)
  			if (errno != EINTR)
  				error("poll error");
  
  		/*
  		 * Handle temporary errors, but bail if they persist.
  		 */
  		if (nfds == 0 || !(pfd[0].revents & POLLIN)) {
  			if (pfail > POLL_FAILURES)
  				error("poll failed > %d times", POLL_FAILURES);
  			sleep(pfail * POLL_FAILURE_WAIT);
  			pfail++;
  			continue;
  		}
  
  		dispatch_imsg(fd);
  	}
  }
  
  void
  get_ifname(char *ifname, char *arg)
  {
  	struct ifgroupreq ifgr;
  	struct ifg_req *ifg;
  	int s, len;
  
  	if (!strcmp(arg, "egress")) {
  		s = socket(AF_INET, SOCK_DGRAM, 0);
  		if (s == -1)
  			error("socket error");
  		bzero(&ifgr, sizeof(ifgr));
  		strlcpy(ifgr.ifgr_name, "egress", sizeof(ifgr.ifgr_name));
  		if (ioctl(s, SIOCGIFGMEMB, (caddr_t)&ifgr) == -1) {
  			if (errno == ENOENT)
  				error("no interface in group egress found");
  			error("ioctl SIOCGIFGMEMB: %m");
  		}
  		len = ifgr.ifgr_len;
  		if ((ifgr.ifgr_groups = calloc(1, len)) == NULL)
  			error("get_ifname");
  		if (ioctl(s, SIOCGIFGMEMB, (caddr_t)&ifgr) == -1)
  			error("ioctl SIOCGIFGMEMB: %m");
  
  		arg = NULL;
  		for (ifg = ifgr.ifgr_groups;
  		     ifg && len >= sizeof(struct ifg_req); ifg++) {
  			len -= sizeof(struct ifg_req);
  			if (arg)
  				error("too many interfaces in group egress");
  			arg = ifg->ifgrq_member;
  		}
  
  		if (strlcpy(ifi->name, arg, IFNAMSIZ) >= IFNAMSIZ)
  			error("Interface name too long: %m");
  
  		free(ifgr.ifgr_groups);
  		close(s);
  	} else if (strlcpy(ifi->name, arg, IFNAMSIZ) >= IFNAMSIZ)
  		error("Interface name too long");
  }
  
  static
  void
  sig_handle(int signo)
  {
  	if (monitor_pid > 0)
  		kill(monitor_pid, signo);
  	fprintf(stderr, "killed by signal\n");
  	exit(1);
  }
  
  static
  int
  killclient(int fd)
  {
  	int noclient = 1;
  
  	/*
  	 * Kill previously running dhclient
  	 */
  	if (flock(fd, LOCK_EX|LOCK_NB) < 0) {
  		char buf[256];
  		ssize_t n;
  		pid_t pid;
  
  		lseek(fd, 0L, SEEK_SET);
  		n = read(fd, buf, sizeof(buf));
  		if (n > 0) {
  			buf[n-1] = 0;
  			pid = strtol(buf, NULL, 10);
  			if ((int)pid > 0) {
  				noclient = 0;
  				kill(pid, SIGINT);
  			}
  		}
  		if (flock(fd, LOCK_EX|LOCK_NB) < 0)
  			usleep(20000);
  		while (flock(fd, LOCK_EX|LOCK_NB) < 0)
  			sleep(1);
  	}
  	return noclient;
  }
  