Add references to mount_hammer2.8 in a few manual pages.

[dragonfly.git] / sbin / dhclient / dhclient.c

/*
 * 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");
                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);
        }

        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;
}