Implement pci_enable_msi() and pci_disable_msi() in the LinuxKPI.

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

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

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

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "dhcpd.h"
#include "privsep.h"

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

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

#include <net80211/ieee80211_freebsd.h>


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

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

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

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

cap_channel_t *capsyslog;

time_t cur_time;
static time_t default_lease_time = 43200; /* 12 hours... */

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

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

static char hostname[_POSIX_HOST_NAME_MAX + 1];

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

static char *path_dhclient_pidfile;
struct pidfh *pidfile;

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

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

int             log_priority;
static int              no_daemon;
static int              unknown_ok = 1;
static int              routefd;

struct interface_info   *ifi;

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

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

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

static time_t   scripttime;

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

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

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

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

        return (NULL);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

static void
init_casper(void)
{
        cap_channel_t           *casper;

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

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

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

        init_casper();

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

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

        argc -= optind;
        argv += optind;

        if (argc != 1)
                usage();

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

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

        if (quiet)
                log_perror = 0;

        tzset();
        time(&cur_time);

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

        read_client_conf();

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

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

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

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

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

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

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

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

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

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

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

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

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

        endpwent();

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

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

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

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

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

        if (immediate_daemon)
                go_daemon();

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

        bootp_packet_handler = do_packet;

        dispatch();

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

void
usage(void)
{

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

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

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

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

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

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

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

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

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

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

        ASSERT_STATE(state, S_INIT);

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

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

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

        ASSERT_STATE(state, S_SELECTING);

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

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

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

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

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

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

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

                ip->client->state = S_REQUESTING;

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

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

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

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

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

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

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

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

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

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

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

        ip->client->new = lease;

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

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

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

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

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

        bind_lease(ip);
}

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

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

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

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

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

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

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

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

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

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

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

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

        ASSERT_STATE(state, S_BOUND);

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

        /* Send out an ARP Request for the offered IP address. */
        script_init("ARPSEND", lease->medium);
        script_write_params("check_", lease);
        /* If the script can't send an ARP request without waiting,
           we'll be waiting when we do the ARPCHECK, so don't wait now. */
        if (script_go())
                arp_timeout_needed = 0;
        else
                arp_timeout_needed = 2;

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

        /* If this is the lease we asked for, put it at the head of the
           list, and don't mess with the arp request timeout. */
        if (lease->address.len == ip->client->requested_address.len &&
            !memcmp(lease->address.iabuf,
            ip->client->requested_address.iabuf,
            ip->client->requested_address.len)) {
                lease->next = ip->client->offered_leases;
                ip->client->offered_leases = lease;
        } else {
                /* If we already have an offer, and arping for this
                   offer would take us past the selection timeout,
                   then don't extend the timeout - just hope for the
                   best. */
                if (ip->client->offered_leases &&
                    (cur_time + arp_timeout_needed) > stop_selecting)
                        arp_timeout_needed = 0;

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

        /* If we're supposed to stop selecting before we've had time
           to wait for the ARPREPLY, add some delay to wait for
           the ARPREPLY. */
        if (stop_selecting - cur_time < arp_timeout_needed)
                stop_selecting = cur_time + arp_timeout_needed;

        /* If the selecting interval has expired, go immediately to
           state_selecting().  Otherwise, time out into
           state_selecting at the select interval. */
        if (stop_selecting <= 0)
                state_selecting(ip);
        else {
                add_timeout(stop_selecting, state_selecting, ip);
                cancel_timeout(send_discover, ip);
        }
}

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

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

        lease = malloc(sizeof(struct client_lease));

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        note("No DHCPOFFERS received.");

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

static FILE *leaseFile;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        scripttime = time(NULL);

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

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

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

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

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

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

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

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

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

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

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

        scripttime = time(NULL);

        return (ret);
}

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

        scripttime = time(NULL);

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

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

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

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

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

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

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

        namelen = strlen(name);

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

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

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

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

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

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

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

        buf[i] = 0;
        return 1;
}

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

        if (no_daemon || state)
                return;

        state = 1;

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

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

        cap_rights_init(&rights);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

                dispatch_imsg(ifi, fd);
        }
}