sbin/dhcpagent/agent.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/types.h>
#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <locale.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <dhcp_hostconf.h>
#include <dhcpagent_ipc.h>
#include <dhcpagent_util.h>
#include <dhcpmsg.h>
#include <netinet/dhcp.h>
#include <net/route.h>
#include <sys/sockio.h>
#include <sys/stat.h>
#include <stropts.h>
#include <fcntl.h>
#include <sys/scsi/adapters/iscsi_if.h>

#include "async.h"
#include "agent.h"
#include "script_handler.h"
#include "util.h"
#include "class_id.h"
#include "states.h"
#include "packet.h"
#include "interface.h"
#include "defaults.h"

#ifndef TEXT_DOMAIN
#define TEXT_DOMAIN "SYS_TEST"
#endif

iu_timer_id_t       inactivity_id;
int         class_id_len = 0;
char            *class_id;
iu_eh_t         *eh;
iu_tq_t         *tq;
pid_t           grandparent;
int         rtsock_fd;

static boolean_t    shutdown_started = B_FALSE;
static boolean_t    do_adopt = B_FALSE;
static unsigned int debug_level = 0;
static iu_eh_callback_t accept_event, ipc_event, rtsock_event;

/*
 * The ipc_cmd_allowed[] table indicates which IPC commands are allowed in
 * which states; a non-zero value indicates the command is permitted.
 *
 * START is permitted if the state machine is fresh, or if we are in the
 * process of trying to obtain a lease (as a convenience to save the
 * administrator from having to do an explicit DROP).  EXTEND, RELEASE, and
 * GET_TAG require a lease to be obtained in order to make sense.  INFORM is
 * permitted if the interface is fresh or has an INFORM in progress or
 * previously done on it -- otherwise a DROP or RELEASE is first required.
 * PING and STATUS always make sense and thus are always permitted, as is DROP
 * in order to permit the administrator to always bail out.
 */
static int ipc_cmd_allowed[DHCP_NSTATES][DHCP_NIPC] = {
    /*            D  E  P  R  S  S  I  G */
    /*            R  X  I  E  T  T  N  E */
    /*            O  T  N  L  A  A  F  T */
    /*            P  E  G  E  R  T  O  _ */
    /*            .  N  .  A  T  U  R  T */
    /*            .  D  .  S  .  S  M  A */
    /*            .  .  .  E  .  .  .  G */
    /* INIT     */  { 1, 0, 1, 0, 1, 1, 1, 0 },
    /* SELECTING    */  { 1, 0, 1, 0, 1, 1, 0, 0 },
    /* REQUESTING   */  { 1, 0, 1, 0, 1, 1, 0, 0 },
    /* PRE_BOUND    */  { 1, 1, 1, 1, 0, 1, 0, 1 },
    /* BOUND    */  { 1, 1, 1, 1, 0, 1, 0, 1 },
    /* RENEWING */  { 1, 1, 1, 1, 0, 1, 0, 1 },
    /* REBINDING    */  { 1, 1, 1, 1, 0, 1, 0, 1 },
    /* INFORMATION  */  { 1, 0, 1, 0, 1, 1, 1, 1 },
    /* INIT_REBOOT  */  { 1, 0, 1, 1, 1, 1, 0, 0 },
    /* ADOPTING */  { 1, 0, 1, 1, 0, 1, 0, 0 },
    /* INFORM_SENT  */  { 1, 0, 1, 0, 1, 1, 1, 0 },
    /* DECLINING    */  { 1, 1, 1, 1, 0, 1, 0, 1 },
    /* RELEASING    */  { 1, 0, 1, 0, 0, 1, 0, 1 },
};

#define CMD_ISPRIV  0x1 /* Command requires privileges */
#define CMD_CREATE  0x2 /* Command creates an interface */
#define CMD_BOOTP   0x4 /* Command is valid with BOOTP */
#define CMD_IMMED   0x8 /* Reply is immediate (no BUSY state) */

static uint_t ipc_cmd_flags[DHCP_NIPC] = {
    /* DHCP_DROP */     CMD_ISPRIV|CMD_BOOTP,
    /* DHCP_EXTEND */   CMD_ISPRIV,
    /* DHCP_PING */     CMD_BOOTP|CMD_IMMED,
    /* DHCP_RELEASE */  CMD_ISPRIV,
    /* DHCP_START */    CMD_CREATE|CMD_ISPRIV|CMD_BOOTP,
    /* DHCP_STATUS */   CMD_BOOTP|CMD_IMMED,
    /* DHCP_INFORM */   CMD_CREATE|CMD_ISPRIV,
    /* DHCP_GET_TAG */  CMD_BOOTP|CMD_IMMED
};

static boolean_t is_iscsi_active(void);

int
main(int argc, char **argv)
{
    boolean_t   is_daemon  = B_TRUE;
    boolean_t   is_verbose;
    int     ipc_fd;
    int     c;
    int     aware = RTAW_UNDER_IPMP;
    struct rlimit   rl;

    debug_level = df_get_int("", B_FALSE, DF_DEBUG_LEVEL);
    is_verbose = df_get_bool("", B_FALSE, DF_VERBOSE);

    /*
     * -l is ignored for compatibility with old agent.
     */

    while ((c = getopt(argc, argv, "vd:l:fa")) != EOF) {

        switch (c) {

        case 'a':
            do_adopt = B_TRUE;
            grandparent = getpid();
            break;

        case 'd':
            debug_level = strtoul(optarg, NULL, 0);
            break;

        case 'f':
            is_daemon = B_FALSE;
            break;

        case 'v':
            is_verbose = B_TRUE;
            break;

        case '?':
            (void) fprintf(stderr, "usage: %s [-a] [-d n] [-f] [-v]"
                "\n", argv[0]);
            return (EXIT_FAILURE);

        default:
            break;
        }
    }

    (void) setlocale(LC_ALL, "");
    (void) textdomain(TEXT_DOMAIN);

    if (geteuid() != 0) {
        dhcpmsg_init(argv[0], B_FALSE, is_verbose, debug_level);
        dhcpmsg(MSG_ERROR, "must be super-user");
        dhcpmsg_fini();
        return (EXIT_FAILURE);
    }

    if (is_daemon && daemonize() == 0) {
        dhcpmsg_init(argv[0], B_FALSE, is_verbose, debug_level);
        dhcpmsg(MSG_ERR, "cannot become daemon, exiting");
        dhcpmsg_fini();
        return (EXIT_FAILURE);
    }

    /*
     * Seed the random number generator, since we're going to need it
     * to set transaction id's and for exponential backoff.
     */
    srand48(gethrtime() ^ gethostid() ^ getpid());

    dhcpmsg_init(argv[0], is_daemon, is_verbose, debug_level);
    (void) atexit(dhcpmsg_fini);

    tq = iu_tq_create();
    eh = iu_eh_create();

    if (eh == NULL || tq == NULL) {
        errno = ENOMEM;
        dhcpmsg(MSG_ERR, "cannot create timer queue or event handler");
        return (EXIT_FAILURE);
    }

    /*
     * ignore most signals that could be reasonably generated.
     */

    (void) signal(SIGTERM, graceful_shutdown);
    (void) signal(SIGQUIT, graceful_shutdown);
    (void) signal(SIGPIPE, SIG_IGN);
    (void) signal(SIGUSR1, SIG_IGN);
    (void) signal(SIGUSR2, SIG_IGN);
    (void) signal(SIGINT,  SIG_IGN);
    (void) signal(SIGHUP,  SIG_IGN);
    (void) signal(SIGCHLD, SIG_IGN);

    /*
     * upon SIGTHAW we need to refresh any non-infinite leases.
     */

    (void) iu_eh_register_signal(eh, SIGTHAW, refresh_smachs, NULL);

    class_id = get_class_id();
    if (class_id != NULL)
        class_id_len = strlen(class_id);
    else
        dhcpmsg(MSG_WARNING, "get_class_id failed, continuing "
            "with no vendor class id");

    /*
     * the inactivity timer is enabled any time there are no
     * interfaces under DHCP control.  if DHCP_INACTIVITY_WAIT
     * seconds transpire without an interface under DHCP control,
     * the agent shuts down.
     */

    inactivity_id = iu_schedule_timer(tq, DHCP_INACTIVITY_WAIT,
        inactivity_shutdown, NULL);

    /*
     * max out the number available descriptors, just in case..
     */

    rl.rlim_cur = RLIM_INFINITY;
    rl.rlim_max = RLIM_INFINITY;
    if (setrlimit(RLIMIT_NOFILE, &rl) == -1)
        dhcpmsg(MSG_ERR, "setrlimit failed");

    (void) enable_extended_FILE_stdio(-1, -1);

    /*
     * Create and bind default IP sockets used to control interfaces and to
     * catch stray packets.
     */

    if (!dhcp_ip_default())
        return (EXIT_FAILURE);

    /*
     * create the ipc channel that the agent will listen for
     * requests on, and register it with the event handler so that
     * `accept_event' will be called back.
     */

    switch (dhcp_ipc_init(&ipc_fd)) {

    case 0:
        break;

    case DHCP_IPC_E_BIND:
        dhcpmsg(MSG_ERROR, "dhcp_ipc_init: cannot bind to port "
            "%i (agent already running?)", IPPORT_DHCPAGENT);
        return (EXIT_FAILURE);

    default:
        dhcpmsg(MSG_ERROR, "dhcp_ipc_init failed");
        return (EXIT_FAILURE);
    }

    if (iu_register_event(eh, ipc_fd, POLLIN, accept_event, 0) == -1) {
        dhcpmsg(MSG_ERR, "cannot register ipc fd for messages");
        return (EXIT_FAILURE);
    }

    /*
     * Create the global routing socket.  This is used for monitoring
     * interface transitions, so that we learn about the kernel's Duplicate
     * Address Detection status, and for inserting and removing default
     * routes as learned from DHCP servers.  Both v4 and v6 are handed
     * with this one socket.
     */
    rtsock_fd = socket(PF_ROUTE, SOCK_RAW, 0);
    if (rtsock_fd == -1) {
        dhcpmsg(MSG_ERR, "cannot open routing socket");
        return (EXIT_FAILURE);
    }

    /*
     * We're IPMP-aware and can manage IPMP test addresses, so issue
     * RT_AWARE to get routing socket messages for interfaces under IPMP.
     */
    if (setsockopt(rtsock_fd, SOL_ROUTE, RT_AWARE, &aware,
        sizeof (aware)) == -1) {
        dhcpmsg(MSG_ERR, "cannot set RT_AWARE on routing socket");
        return (EXIT_FAILURE);
    }

    if (iu_register_event(eh, rtsock_fd, POLLIN, rtsock_event, 0) == -1) {
        dhcpmsg(MSG_ERR, "cannot register routing socket for messages");
        return (EXIT_FAILURE);
    }

    /*
     * if the -a (adopt) option was specified, try to adopt the
     * kernel-managed interface before we start.
     */

    if (do_adopt && !dhcp_adopt())
        return (EXIT_FAILURE);

    /*
     * For DHCPv6, we own all of the interfaces marked DHCPRUNNING.  As
     * we're starting operation here, if there are any of those interfaces
     * lingering around, they're strays, and need to be removed.
     *
     * It might be nice to save these addresses off somewhere -- for both
     * v4 and v6 -- and use them as hints for later negotiation.
     */
    remove_v6_strays();

    /*
     * enter the main event loop; this is where all the real work
     * takes place (through registering events and scheduling timers).
     * this function only returns when the agent is shutting down.
     */

    switch (iu_handle_events(eh, tq)) {

    case -1:
        dhcpmsg(MSG_WARNING, "iu_handle_events exited abnormally");
        break;

    case DHCP_REASON_INACTIVITY:
        dhcpmsg(MSG_INFO, "no interfaces to manage, shutting down...");
        break;

    case DHCP_REASON_TERMINATE:
        dhcpmsg(MSG_INFO, "received SIGTERM, shutting down...");
        break;

    case DHCP_REASON_SIGNAL:
        dhcpmsg(MSG_WARNING, "received unexpected signal, shutting "
            "down...");
        break;
    }

    (void) iu_eh_unregister_signal(eh, SIGTHAW, NULL);

    iu_eh_destroy(eh);
    iu_tq_destroy(tq);

    return (EXIT_SUCCESS);
}

/*
 * drain_script(): event loop callback during shutdown
 *
 *   input: eh_t *: unused
 *      void *: unused
 *  output: boolean_t: B_TRUE if event loop should exit; B_FALSE otherwise
 */

/* ARGSUSED */
boolean_t
drain_script(iu_eh_t *ehp, void *arg)
{
    if (shutdown_started == B_FALSE) {
        shutdown_started = B_TRUE;
        /*
         * Check if the system is diskless client and/or
         * there are active iSCSI sessions
         *
         * Do not drop the lease, or the system will be
         * unable to sync(dump) through nfs/iSCSI driver
         */
        if (!do_adopt && !is_iscsi_active()) {
            nuke_smach_list();
        }
    }
    return (script_count == 0);
}

/*
 * accept_event(): accepts a new connection on the ipc socket and registers
 *         to receive its messages with the event handler
 *
 *   input: iu_eh_t *: unused
 *      int: the file descriptor in the iu_eh_t * the connection came in on
 *      (other arguments unused)
 *  output: void
 */

/* ARGSUSED */
static void
accept_event(iu_eh_t *ehp, int fd, short events, iu_event_id_t id, void *arg)
{
    int client_fd;
    int is_priv;

    if (dhcp_ipc_accept(fd, &client_fd, &is_priv) != 0) {
        dhcpmsg(MSG_ERR, "accept_event: accept on ipc socket");
        return;
    }

    if (iu_register_event(eh, client_fd, POLLIN, ipc_event,
        (void *)is_priv) == -1) {
        dhcpmsg(MSG_ERROR, "accept_event: cannot register ipc socket "
            "for callback");
    }
}

/*
 * ipc_event(): processes incoming ipc requests
 *
 *   input: iu_eh_t *: unused
 *      int: the file descriptor in the iu_eh_t * the request came in on
 *      short: unused
 *      iu_event_id_t: event ID
 *      void *: indicates whether the request is from a privileged client
 *  output: void
 */

/* ARGSUSED */
static void
ipc_event(iu_eh_t *ehp, int fd, short events, iu_event_id_t id, void *arg)
{
    ipc_action_t        ia, *iap;
    dhcp_smach_t        *dsmp;
    int         error, is_priv = (int)arg;
    const char      *ifname;
    boolean_t       isv6;
    boolean_t       dsm_created = B_FALSE;

    ipc_action_init(&ia);
    error = dhcp_ipc_recv_request(fd, &ia.ia_request,
        DHCP_IPC_REQUEST_WAIT);
    if (error != DHCP_IPC_SUCCESS) {
        if (error != DHCP_IPC_E_EOF) {
            dhcpmsg(MSG_ERROR,
                "ipc_event: dhcp_ipc_recv_request failed: %s",
                dhcp_ipc_strerror(error));
        } else {
            dhcpmsg(MSG_DEBUG, "ipc_event: connection closed");
        }
        if ((dsmp = lookup_smach_by_event(id)) != NULL) {
            ipc_action_finish(dsmp, error);
        } else {
            (void) iu_unregister_event(eh, id, NULL);
            (void) dhcp_ipc_close(fd);
        }
        return;
    }

    /* Fill in temporary ipc_action structure for utility functions */
    ia.ia_cmd = DHCP_IPC_CMD(ia.ia_request->message_type);
    ia.ia_fd = fd;
    ia.ia_eid = id;

    if (ia.ia_cmd >= DHCP_NIPC) {
        dhcpmsg(MSG_ERROR,
            "ipc_event: invalid command (%s) attempted on %s",
            dhcp_ipc_type_to_string(ia.ia_cmd), ia.ia_request->ifname);
        send_error_reply(&ia, DHCP_IPC_E_CMD_UNKNOWN);
        return;
    }

    /* return EPERM for any of the privileged actions */

    if (!is_priv && (ipc_cmd_flags[ia.ia_cmd] & CMD_ISPRIV)) {
        dhcpmsg(MSG_WARNING,
            "ipc_event: privileged ipc command (%s) attempted on %s",
            dhcp_ipc_type_to_string(ia.ia_cmd), ia.ia_request->ifname);
        send_error_reply(&ia, DHCP_IPC_E_PERM);
        return;
    }

    /*
     * Try to locate the state machine associated with this command.  If
     * the command is DHCP_START or DHCP_INFORM and there isn't a state
     * machine already, make one (there may already be one from a previous
     * failed attempt to START or INFORM).  Otherwise, verify the reference
     * is still valid.
     *
     * The interface name may be blank.  In that case, we look up the
     * primary interface, and the requested type (v4 or v6) doesn't matter.
     */

    isv6 = (ia.ia_request->message_type & DHCP_V6) != 0;
    ifname = ia.ia_request->ifname;
    if (*ifname == '\0')
        dsmp = primary_smach(isv6);
    else
        dsmp = lookup_smach(ifname, isv6);

    if (dsmp != NULL) {
        /* Note that verify_smach drops a reference */
        hold_smach(dsmp);
        if (!verify_smach(dsmp))
            dsmp = NULL;
    }

    if (dsmp == NULL) {
        /*
         * If the user asked for the primary DHCP interface by giving
         * an empty string and there is no primary, then check if we're
         * handling dhcpinfo.  If so, then simulate primary selection.
         * Otherwise, report failure.
         */
        if (ifname[0] == '\0') {
            if (ia.ia_cmd == DHCP_GET_TAG)
                dsmp = info_primary_smach(isv6);
            if (dsmp == NULL)
                error = DHCP_IPC_E_NOPRIMARY;

        /*
         * If there's no interface, and we're starting up, then create
         * it now, along with a state machine for it.  Note that if
         * insert_smach fails, it discards the LIF reference.
         */
        } else if (ipc_cmd_flags[ia.ia_cmd] & CMD_CREATE) {
            dhcp_lif_t *lif;

            lif = attach_lif(ifname, isv6, &error);
            if (lif != NULL &&
                (dsmp = insert_smach(lif, &error)) != NULL) {
                /*
                 * Get client ID for logical interface.  (V4
                 * only, because V6 plumbs its own interfaces.)
                 */
                error = get_smach_cid(dsmp);
                if (error != DHCP_IPC_SUCCESS) {
                    remove_smach(dsmp);
                    dsmp = NULL;
                }
                dsm_created = (dsmp != NULL);
            }

        /*
         * Otherwise, this is an operation on an unknown interface.
         */
        } else {
            error = DHCP_IPC_E_UNKIF;
        }
        if (dsmp == NULL) {
            send_error_reply(&ia, error);
            return;
        }
    }

    /*
     * If this is a request for DHCP to manage a lease on an address,
     * ensure that IFF_DHCPRUNNING is set (we don't set this when the lif
     * is created because the lif may have been created for INFORM).
     */
    if (ia.ia_cmd == DHCP_START &&
        (error = set_lif_dhcp(dsmp->dsm_lif)) != DHCP_IPC_SUCCESS) {
        if (dsm_created)
            remove_smach(dsmp);
        send_error_reply(&ia, error);
        return;
    }

    if ((dsmp->dsm_dflags & DHCP_IF_BOOTP) &&
        !(ipc_cmd_flags[ia.ia_cmd] & CMD_BOOTP)) {
        dhcpmsg(MSG_ERROR, "command %s not valid for BOOTP on %s",
            dhcp_ipc_type_to_string(ia.ia_cmd), dsmp->dsm_name);
        send_error_reply(&ia, DHCP_IPC_E_BOOTP);
        return;
    }

    /*
     * verify that the state machine is in a state which will allow the
     * command.  we do this up front so that we can return an error
     * *before* needlessly cancelling an in-progress transaction.
     */

    if (!check_cmd_allowed(dsmp->dsm_state, ia.ia_cmd)) {
        dhcpmsg(MSG_DEBUG,
            "in state %s; not allowing %s command on %s",
            dhcp_state_to_string(dsmp->dsm_state),
            dhcp_ipc_type_to_string(ia.ia_cmd), dsmp->dsm_name);
        send_error_reply(&ia,
            ia.ia_cmd == DHCP_START && dsmp->dsm_state != INIT ?
            DHCP_IPC_E_RUNNING : DHCP_IPC_E_OUTSTATE);
        return;
    }

    dhcpmsg(MSG_DEBUG, "in state %s; allowing %s command on %s",
        dhcp_state_to_string(dsmp->dsm_state),
        dhcp_ipc_type_to_string(ia.ia_cmd), dsmp->dsm_name);

    if ((ia.ia_request->message_type & DHCP_PRIMARY) && is_priv)
        make_primary(dsmp);

    /*
     * The current design dictates that there can be only one outstanding
     * transaction per state machine -- this simplifies the code
     * considerably and also fits well with RFCs 2131 and 3315.  It is
     * worth classifying the different DHCP commands into synchronous
     * (those which we will handle now and reply to immediately) and
     * asynchronous (those which require transactions and will be completed
     * at an indeterminate time in the future):
     *
     *    DROP: removes the agent's management of a state machine.
     *      asynchronous as the script program may be invoked.
     *
     *    PING: checks to see if the agent has a named state machine.
     *      synchronous, since no packets need to be sent
     *      to the DHCP server.
     *
     *  STATUS: returns information about a state machine.
     *      synchronous, since no packets need to be sent
     *      to the DHCP server.
     *
     * RELEASE: releases the agent's management of a state machine
     *      and brings the associated interfaces down.  asynchronous
     *      as the script program may be invoked.
     *
     *  EXTEND: renews a lease.  asynchronous, since the agent
     *      needs to wait for an ACK, etc.
     *
     *   START: starts DHCP on a named state machine.  asynchronous since
     *      the agent needs to wait for OFFERs, ACKs, etc.
     *
     *  INFORM: obtains configuration parameters for the system using
     *      externally configured interface.  asynchronous, since the
     *      agent needs to wait for an ACK.
     *
     * Notice that EXTEND, INFORM, START, DROP and RELEASE are
     * asynchronous.  Notice also that asynchronous commands may occur from
     * within the agent -- for instance, the agent will need to do implicit
     * EXTENDs to extend the lease. In order to make the code simpler, the
     * following rules apply for asynchronous commands:
     *
     * There can only be one asynchronous command at a time per state
     * machine.  The current asynchronous command is managed by the async_*
     * api: async_start(), async_finish(), and async_cancel().
     * async_start() starts management of a new asynchronous command on an
     * state machine, which should only be done after async_cancel() to
     * terminate a previous command.  When the command is completed,
     * async_finish() should be called.
     *
     * Asynchronous commands started by a user command have an associated
     * ipc_action which provides the agent with information for how to get
     * in touch with the user command when the action completes.  These
     * ipc_action records also have an associated timeout which may be
     * infinite.  ipc_action_start() should be called when starting an
     * asynchronous command requested by a user, which sets up the timer
     * and keeps track of the ipc information (file descriptor, request
     * type).  When the asynchronous command completes, ipc_action_finish()
     * should be called to return a command status code to the user and
     * close the ipc connection).  If the command does not complete before
     * the timer fires, ipc_action_timeout() is called which closes the ipc
     * connection and returns DHCP_IPC_E_TIMEOUT to the user.  Note that
     * independent of ipc_action_timeout(), ipc_action_finish() should be
     * called.
     *
     * on a case-by-case basis, here is what happens (per state machine):
     *
     *    o When an asynchronous command is requested, then
     *  async_cancel() is called to terminate any non-user
     *  action in progress.  If there's a user action running,
     *  the user command is sent DHCP_IPC_E_PEND.
     *
     *    o otherwise, the the transaction is started with
     *  async_start().  if the transaction is on behalf
     *  of a user, ipc_action_start() is called to keep
     *  track of the ipc information and set up the
     *  ipc_action timer.
     *
     *    o if the command completes normally and before a
     *  timeout fires, then async_finish() is called.
     *  if there was an associated ipc_action,
     *  ipc_action_finish() is called to complete it.
     *
     *    o if the command fails before a timeout fires, then
     *  async_finish() is called, and the state machine is
     *  is returned to a known state based on the command.
     *  if there was an associated ipc_action,
     *  ipc_action_finish() is called to complete it.
     *
     *    o if the ipc_action timer fires before command
     *  completion, then DHCP_IPC_E_TIMEOUT is returned to
     *  the user.  however, the transaction continues to
     *  be carried out asynchronously.
     */

    if (ipc_cmd_flags[ia.ia_cmd] & CMD_IMMED) {
        /*
         * Only immediate commands (ping, status, get_tag) need to
         * worry about freeing ia through one of the reply functions
         * before returning.
         */
        iap = &ia;
    } else {
        /*
         * if shutdown request has been received, send back an error.
         */
        if (shutdown_started) {
            send_error_reply(&ia, DHCP_IPC_E_OUTSTATE);
            return;
        }

        if (dsmp->dsm_dflags & DHCP_IF_BUSY) {
            send_error_reply(&ia, DHCP_IPC_E_PEND);
            return;
        }

        if (!ipc_action_start(dsmp, &ia)) {
            dhcpmsg(MSG_WARNING, "ipc_event: ipc_action_start "
                "failed for %s", dsmp->dsm_name);
            send_error_reply(&ia, DHCP_IPC_E_MEMORY);
            return;
        }

        /* Action structure consumed by above function */
        iap = &dsmp->dsm_ia;
    }

    switch (iap->ia_cmd) {

    case DHCP_DROP:
        if (dsmp->dsm_droprelease)
            break;
        dsmp->dsm_droprelease = B_TRUE;

        /*
         * Ensure that a timer associated with the existing state
         * doesn't pop while we're waiting for the script to complete.
         * (If so, chaos can result -- e.g., a timer causes us to end
         * up in dhcp_selecting() would start acquiring a new lease on
         * dsmp while our DHCP_DROP dismantling is ongoing.)
         */
        cancel_smach_timers(dsmp);
        (void) script_start(dsmp, isv6 ? EVENT_DROP6 : EVENT_DROP,
            dhcp_drop, NULL, NULL);
        break;      /* not an immediate function */

    case DHCP_EXTEND:
        (void) dhcp_extending(dsmp);
        break;

    case DHCP_GET_TAG: {
        dhcp_optnum_t   optnum;
        void        *opt = NULL;
        uint_t      optlen;
        boolean_t   did_alloc = B_FALSE;
        PKT_LIST    *ack = dsmp->dsm_ack;
        int     i;

        /*
         * verify the request makes sense.
         */

        if (iap->ia_request->data_type   != DHCP_TYPE_OPTNUM ||
            iap->ia_request->data_length != sizeof (dhcp_optnum_t)) {
            send_error_reply(iap, DHCP_IPC_E_PROTO);
            break;
        }

        (void) memcpy(&optnum, iap->ia_request->buffer,
            sizeof (dhcp_optnum_t));

load_option:
        switch (optnum.category) {

        case DSYM_SITE:         /* FALLTHRU */
        case DSYM_STANDARD:
            for (i = 0; i < dsmp->dsm_pillen; i++) {
                if (dsmp->dsm_pil[i] == optnum.code)
                    break;
            }
            if (i < dsmp->dsm_pillen)
                break;
            if (isv6) {
                opt = dhcpv6_pkt_option(ack, NULL, optnum.code,
                    NULL);
            } else {
                if (optnum.code <= DHCP_LAST_OPT)
                    opt = ack->opts[optnum.code];
            }
            break;

        case DSYM_VENDOR:
            if (isv6) {
                dhcpv6_option_t *d6o;
                uint32_t ent;

                /*
                 * Look through vendor options to find our
                 * enterprise number.
                 */
                d6o = NULL;
                for (;;) {
                    d6o = dhcpv6_pkt_option(ack, d6o,
                        DHCPV6_OPT_VENDOR_OPT, &optlen);
                    if (d6o == NULL)
                        break;
                    optlen -= sizeof (*d6o);
                    if (optlen < sizeof (ent))
                        continue;
                    (void) memcpy(&ent, d6o + 1,
                        sizeof (ent));
                    if (ntohl(ent) != DHCPV6_SUN_ENT)
                        continue;
                    break;
                }
                if (d6o != NULL) {
                    /*
                     * Now find the requested vendor option
                     * within the vendor options block.
                     */
                    opt = dhcpv6_find_option(
                        (char *)(d6o + 1) + sizeof (ent),
                        optlen - sizeof (ent), NULL,
                        optnum.code, NULL);
                }
            } else {
                /*
                 * the test against VS_OPTION_START is broken
                 * up into two tests to avoid compiler warnings
                 * under intel.
                 */
                if ((optnum.code > VS_OPTION_START ||
                    optnum.code == VS_OPTION_START) &&
                    optnum.code <= VS_OPTION_END)
                    opt = ack->vs[optnum.code];
            }
            break;

        case DSYM_FIELD:
            if (isv6) {
                dhcpv6_message_t *d6m =
                    (dhcpv6_message_t *)ack->pkt;
                dhcpv6_option_t *d6o;

                /* Validate the packet field the user wants */
                optlen = optnum.code + optnum.size;
                if (d6m->d6m_msg_type ==
                    DHCPV6_MSG_RELAY_FORW ||
                    d6m->d6m_msg_type ==
                    DHCPV6_MSG_RELAY_REPL) {
                    if (optlen > sizeof (dhcpv6_relay_t))
                        break;
                } else {
                    if (optlen > sizeof (*d6m))
                        break;
                }

                opt = malloc(sizeof (*d6o) + optnum.size);
                if (opt != NULL) {
                    d6o = opt;
                    d6o->d6o_code = htons(optnum.code);
                    d6o->d6o_len = htons(optnum.size);
                    (void) memcpy(d6o + 1, (caddr_t)d6m +
                        optnum.code, optnum.size);
                }
            } else {
                if (optnum.code + optnum.size > sizeof (PKT))
                    break;

                /*
                 * + 2 to account for option code and length
                 * byte
                 */
                opt = malloc(optnum.size + 2);
                if (opt != NULL) {
                    DHCP_OPT *v4opt = opt;

                    v4opt->len  = optnum.size;
                    v4opt->code = optnum.code;
                    (void) memcpy(v4opt->value,
                        (caddr_t)ack->pkt + optnum.code,
                        optnum.size);
                }
            }

            if (opt == NULL) {
                send_error_reply(iap, DHCP_IPC_E_MEMORY);
                return;
            }
            did_alloc = B_TRUE;
            break;

        default:
            send_error_reply(iap, DHCP_IPC_E_PROTO);
            return;
        }

        /*
         * return the option payload, if there was one.  the "+ 2"
         * accounts for the option code number and length byte.
         */

        if (opt != NULL) {
            if (isv6) {
                dhcpv6_option_t d6ov;

                (void) memcpy(&d6ov, opt, sizeof (d6ov));
                optlen = ntohs(d6ov.d6o_len) + sizeof (d6ov);
            } else {
                optlen = ((DHCP_OPT *)opt)->len + 2;
            }
            send_data_reply(iap, 0, DHCP_TYPE_OPTION, opt, optlen);

            if (did_alloc)
                free(opt);
            break;
        } else if (ack != dsmp->dsm_orig_ack) {
            /*
             * There wasn't any definition for the option in the
             * current ack, so now retry with the original ack if
             * the original ack is not the current ack.
             */
            ack = dsmp->dsm_orig_ack;
            goto load_option;
        }

        /*
         * note that an "okay" response is returned either in
         * the case of an unknown option or a known option
         * with no payload.  this is okay (for now) since
         * dhcpinfo checks whether an option is valid before
         * ever performing ipc with the agent.
         */

        send_ok_reply(iap);
        break;
    }

    case DHCP_INFORM:
        dhcp_inform(dsmp);
        /* next destination: dhcp_acknak() */
        break;      /* not an immediate function */

    case DHCP_PING:
        if (dsmp->dsm_dflags & DHCP_IF_FAILED)
            send_error_reply(iap, DHCP_IPC_E_FAILEDIF);
        else
            send_ok_reply(iap);
        break;

    case DHCP_RELEASE:
        if (dsmp->dsm_droprelease)
            break;
        dsmp->dsm_droprelease = B_TRUE;
        cancel_smach_timers(dsmp); /* see comment in DHCP_DROP above */
        (void) script_start(dsmp, isv6 ? EVENT_RELEASE6 :
            EVENT_RELEASE, dhcp_release, "Finished with lease.", NULL);
        break;      /* not an immediate function */

    case DHCP_START: {
        PKT_LIST *ack, *oack;
        PKT_LIST *plp[2];

        deprecate_leases(dsmp);

        /*
         * if we have a valid hostconf lying around, then jump
         * into INIT_REBOOT.  if it fails, we'll end up going
         * through the whole selecting() procedure again.
         */

        error = read_hostconf(dsmp->dsm_name, plp, 2, dsmp->dsm_isv6);
        ack = error > 0 ? plp[0] : NULL;
        oack = error > 1 ? plp[1] : NULL;

        /*
         * If the allocation of the old ack fails, that's fine;
         * continue without it.
         */
        if (oack == NULL)
            oack = ack;

        /*
         * As long as we've allocated something, start using it.
         */
        if (ack != NULL) {
            dsmp->dsm_orig_ack = oack;
            dsmp->dsm_ack = ack;
            dhcp_init_reboot(dsmp);
            /* next destination: dhcp_acknak() */
            break;
        }

        /*
         * if not debugging, wait for a few seconds before
         * going into SELECTING.
         */

        if (debug_level == 0 && set_start_timer(dsmp)) {
            /* next destination: dhcp_start() */
            break;
        } else {
            dhcp_selecting(dsmp);
            /* next destination: dhcp_requesting() */
            break;
        }
    }

    case DHCP_STATUS: {
        dhcp_status_t   status;
        dhcp_lease_t    *dlp;

        status.if_began = monosec_to_time(dsmp->dsm_curstart_monosec);

        /*
         * We return information on just the first lease as being
         * representative of the lot.  A better status mechanism is
         * needed.
         */
        dlp = dsmp->dsm_leases;

        if (dlp == NULL ||
            dlp->dl_lifs->lif_expire.dt_start == DHCP_PERM) {
            status.if_t1    = DHCP_PERM;
            status.if_t2    = DHCP_PERM;
            status.if_lease = DHCP_PERM;
        } else {
            status.if_t1    = status.if_began +
                dlp->dl_t1.dt_start;
            status.if_t2    = status.if_began +
                dlp->dl_t2.dt_start;
            status.if_lease = status.if_began +
                dlp->dl_lifs->lif_expire.dt_start;
        }

        status.version      = DHCP_STATUS_VER;
        status.if_state     = dsmp->dsm_state;
        status.if_dflags    = dsmp->dsm_dflags;
        status.if_sent      = dsmp->dsm_sent;
        status.if_recv      = dsmp->dsm_received;
        status.if_bad_offers    = dsmp->dsm_bad_offers;

        (void) strlcpy(status.if_name, dsmp->dsm_name, LIFNAMSIZ);

        send_data_reply(iap, 0, DHCP_TYPE_STATUS, &status,
            sizeof (dhcp_status_t));
        break;
    }
    }
}

/*
 * check_rtm_addr(): determine if routing socket message matches interface
 *           address
 *
 *   input: const struct if_msghdr *: pointer to routing socket message
 *      int: routing socket message length
 *      boolean_t: set to B_TRUE if IPv6
 *      const in6_addr_t *: pointer to IP address
 *  output: boolean_t: B_TRUE if address is a match
 */

static boolean_t
check_rtm_addr(const struct ifa_msghdr *ifam, int msglen, boolean_t isv6,
    const in6_addr_t *addr)
{
    const char *cp, *lim;
    uint_t flag;
    const struct sockaddr *sa;

    if (!(ifam->ifam_addrs & RTA_IFA))
        return (B_FALSE);

    cp = (const char *)(ifam + 1);
    lim = (const char *)ifam + msglen;
    for (flag = 1; flag < RTA_IFA; flag <<= 1) {
        if (ifam->ifam_addrs & flag) {
            /* LINTED: alignment */
            sa = (const struct sockaddr *)cp;
            if ((const char *)(sa + 1) > lim)
                return (B_FALSE);
            switch (sa->sa_family) {
            case AF_INET:
                cp += sizeof (struct sockaddr_in);
                break;
            case AF_LINK:
                cp += sizeof (struct sockaddr_dl);
                break;
            case AF_INET6:
                cp += sizeof (struct sockaddr_in6);
                break;
            default:
                cp += sizeof (struct sockaddr);
                break;
            }
        }
    }
    if (isv6) {
        const struct sockaddr_in6 *sin6;

        /* LINTED: alignment */
        sin6 = (const struct sockaddr_in6 *)cp;
        if ((const char *)(sin6 + 1) > lim)
            return (B_FALSE);
        if (sin6->sin6_family != AF_INET6)
            return (B_FALSE);
        return (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr, addr));
    } else {
        const struct sockaddr_in *sinp;
        ipaddr_t v4addr;

        /* LINTED: alignment */
        sinp = (const struct sockaddr_in *)cp;
        if ((const char *)(sinp + 1) > lim)
            return (B_FALSE);
        if (sinp->sin_family != AF_INET)
            return (B_FALSE);
        IN6_V4MAPPED_TO_IPADDR(addr, v4addr);
        return (sinp->sin_addr.s_addr == v4addr);
    }
}

/*
 * is_rtm_v6(): determine if routing socket message is IPv6
 *
 *   input: struct ifa_msghdr *: pointer to routing socket message
 *      int: message length
 *  output: boolean_t
 */

static boolean_t
is_rtm_v6(const struct ifa_msghdr *ifam, int msglen)
{
    const char *cp, *lim;
    uint_t flag;
    const struct sockaddr *sa;

    cp = (const char *)(ifam + 1);
    lim = (const char *)ifam + msglen;
    for (flag = ifam->ifam_addrs; flag != 0; flag &= flag - 1) {
        /* LINTED: alignment */
        sa = (const struct sockaddr *)cp;
        if ((const char *)(sa + 1) > lim)
            return (B_FALSE);
        switch (sa->sa_family) {
        case AF_INET:
            return (B_FALSE);
        case AF_LINK:
            cp += sizeof (struct sockaddr_dl);
            break;
        case AF_INET6:
            return (B_TRUE);
        default:
            cp += sizeof (struct sockaddr);
            break;
        }
    }
    return (B_FALSE);
}

/*
 * check_lif(): check the state of a given logical interface and its DHCP
 *      lease.  We've been told by the routing socket that the
 *      corresponding ifIndex has changed.  This may mean that DAD has
 *      completed or failed.
 *
 *   input: dhcp_lif_t *: pointer to the LIF
 *      const struct ifa_msghdr *: routing socket message
 *      int: size of routing socket message
 *  output: boolean_t: B_TRUE if DAD has completed on this interface
 */

static boolean_t
check_lif(dhcp_lif_t *lif, const struct ifa_msghdr *ifam, int msglen)
{
    boolean_t isv6, dad_wait, unplumb;
    int fd;
    struct lifreq lifr;

    isv6 = lif->lif_pif->pif_isv6;
    fd = isv6 ? v6_sock_fd : v4_sock_fd;

    /*
     * Get the real (64 bit) logical interface flags.  Note that the
     * routing socket message has flags, but these are just the lower 32
     * bits.
     */
    unplumb = B_FALSE;
    (void) memset(&lifr, 0, sizeof (lifr));
    (void) strlcpy(lifr.lifr_name, lif->lif_name, sizeof (lifr.lifr_name));
    if (ioctl(fd, SIOCGLIFFLAGS, &lifr) == -1) {
        /*
         * Failing to retrieve flags means that the interface is gone.
         * It hasn't failed to verify with DAD, but we still have to
         * give up on it.
         */
        lifr.lifr_flags = 0;
        if (errno == ENXIO) {
            lif->lif_plumbed = B_FALSE;
            dhcpmsg(MSG_INFO, "%s has been removed; abandoning",
                lif->lif_name);
            if (!isv6)
                discard_default_routes(lif->lif_smachs);
        } else {
            dhcpmsg(MSG_ERR,
                "unable to retrieve interface flags on %s",
                lif->lif_name);
        }
        unplumb = B_TRUE;
    } else if (!check_rtm_addr(ifam, msglen, isv6, &lif->lif_v6addr)) {
        /*
         * If the message is not about this logical interface,
         * then just ignore it.
         */
        return (B_FALSE);
    } else if (lifr.lifr_flags & IFF_DUPLICATE) {
        dhcpmsg(MSG_ERROR, "interface %s has duplicate address",
            lif->lif_name);
        lif_mark_decline(lif, "duplicate address");
        close_ip_lif(lif);
        (void) open_ip_lif(lif, INADDR_ANY, B_TRUE);
    }

    dad_wait = lif->lif_dad_wait;
    if (dad_wait) {
        dhcpmsg(MSG_VERBOSE, "check_lif: %s has finished DAD",
            lif->lif_name);
        lif->lif_dad_wait = B_FALSE;
    }

    if (unplumb)
        unplumb_lif(lif);

    return (dad_wait);
}

/*
 * check_main_lif(): check the state of a main logical interface for a state
 *           machine.  This is used only for DHCPv6.
 *
 *   input: dhcp_smach_t *: pointer to the state machine
 *      const struct ifa_msghdr *: routing socket message
 *      int: size of routing socket message
 *  output: boolean_t: B_TRUE if LIF is ok.
 */

static boolean_t
check_main_lif(dhcp_smach_t *dsmp, const struct ifa_msghdr *ifam, int msglen)
{
    dhcp_lif_t *lif = dsmp->dsm_lif;
    struct lifreq lifr;

    /*
     * Get the real (64 bit) logical interface flags.  Note that the
     * routing socket message has flags, but these are just the lower 32
     * bits.
     */
    (void) memset(&lifr, 0, sizeof (lifr));
    (void) strlcpy(lifr.lifr_name, lif->lif_name, sizeof (lifr.lifr_name));
    if (ioctl(v6_sock_fd, SIOCGLIFFLAGS, &lifr) == -1) {
        /*
         * Failing to retrieve flags means that the interface is gone.
         * Our state machine is now trash.
         */
        if (errno == ENXIO) {
            dhcpmsg(MSG_INFO, "%s has been removed; abandoning",
                lif->lif_name);
        } else {
            dhcpmsg(MSG_ERR,
                "unable to retrieve interface flags on %s",
                lif->lif_name);
        }
        return (B_FALSE);
    } else if (!check_rtm_addr(ifam, msglen, B_TRUE, &lif->lif_v6addr)) {
        /*
         * If the message is not about this logical interface,
         * then just ignore it.
         */
        return (B_TRUE);
    } else if (lifr.lifr_flags & IFF_DUPLICATE) {
        dhcpmsg(MSG_ERROR, "interface %s has duplicate address",
            lif->lif_name);
        return (B_FALSE);
    } else {
        return (B_TRUE);
    }
}

/*
 * process_link_up_down(): check the state of a physical interface for up/down
 *             transitions; must go through INIT_REBOOT state if
 *             the link flaps.
 *
 *   input: dhcp_pif_t *: pointer to the physical interface to check
 *      const struct if_msghdr *: routing socket message
 *  output: none
 */

static void
process_link_up_down(dhcp_pif_t *pif, const struct if_msghdr *ifm)
{
    struct lifreq lifr;
    boolean_t isv6;
    int fd;

    /*
     * If the message implies no change of flags, then we're done; no need
     * to check further.  Note that if we have multiple state machines on a
     * single physical interface, this test keeps us from issuing an ioctl
     * for each one.
     */
    if ((ifm->ifm_flags & IFF_RUNNING) && pif->pif_running ||
        !(ifm->ifm_flags & IFF_RUNNING) && !pif->pif_running)
        return;

    /*
     * We don't know what the real interface flags are, because the
     * if_index number is only 16 bits; we must go ask.
     */
    isv6 = pif->pif_isv6;
    fd = isv6 ? v6_sock_fd : v4_sock_fd;
    (void) memset(&lifr, 0, sizeof (lifr));
    (void) strlcpy(lifr.lifr_name, pif->pif_name, sizeof (lifr.lifr_name));

    if (ioctl(fd, SIOCGLIFFLAGS, &lifr) == -1 ||
        !(lifr.lifr_flags & IFF_RUNNING)) {
        /*
         * If we've lost the interface or it has gone down, then
         * nothing special to do; just turn off the running flag.
         */
        pif_status(pif, B_FALSE);
    } else {
        /*
         * Interface has come back up: go through verification process.
         */
        pif_status(pif, B_TRUE);
    }
}

/*
 * rtsock_event(): fetches routing socket messages and updates internal
 *         interface state based on those messages.
 *
 *   input: iu_eh_t *: unused
 *      int: the routing socket file descriptor
 *      (other arguments unused)
 *  output: void
 */

/* ARGSUSED */
static void
rtsock_event(iu_eh_t *ehp, int fd, short events, iu_event_id_t id, void *arg)
{
    dhcp_smach_t *dsmp, *dsmnext;
    union {
        struct ifa_msghdr ifam;
        struct if_msghdr ifm;
        char buf[1024];
    } msg;
    uint16_t ifindex;
    int msglen;
    boolean_t isv6;

    if ((msglen = read(fd, &msg, sizeof (msg))) <= 0)
        return;

    /* Note that the routing socket interface index is just 16 bits */
    if (msg.ifm.ifm_type == RTM_IFINFO) {
        ifindex = msg.ifm.ifm_index;
        isv6 = (msg.ifm.ifm_flags & IFF_IPV6) ? B_TRUE : B_FALSE;
    } else if (msg.ifam.ifam_type == RTM_DELADDR ||
        msg.ifam.ifam_type == RTM_NEWADDR) {
        ifindex = msg.ifam.ifam_index;
        isv6 = is_rtm_v6(&msg.ifam, msglen);
    } else {
        return;
    }

    for (dsmp = lookup_smach_by_uindex(ifindex, NULL, isv6);
        dsmp != NULL; dsmp = dsmnext) {
        DHCPSTATE oldstate;
        boolean_t lif_finished;
        boolean_t lease_removed;
        dhcp_lease_t *dlp, *dlnext;

        /*
         * Note that script_start can call dhcp_drop directly, and
         * that will do release_smach.
         */
        dsmnext = lookup_smach_by_uindex(ifindex, dsmp, isv6);
        oldstate = dsmp->dsm_state;

        /*
         * Ignore state machines that are currently processing drop or
         * release; there is nothing more we can do for them.
         */
        if (dsmp->dsm_droprelease)
            continue;

        /*
         * Look for link up/down notifications.  These occur on a
         * physical interface basis.
         */
        if (msg.ifm.ifm_type == RTM_IFINFO) {
            process_link_up_down(dsmp->dsm_lif->lif_pif, &msg.ifm);
            continue;
        }

        /*
         * Since we cannot trust the flags reported by the routing
         * socket (they're just 32 bits -- and thus never include
         * IFF_DUPLICATE), and we can't trust the ifindex (it's only 16
         * bits and also doesn't reflect the alias in use), we get
         * flags on all matching interfaces, and go by that.
         */
        lif_finished = B_FALSE;
        lease_removed = B_FALSE;
        for (dlp = dsmp->dsm_leases; dlp != NULL; dlp = dlnext) {
            dhcp_lif_t *lif, *lifnext;
            uint_t nlifs = dlp->dl_nlifs;

            dlnext = dlp->dl_next;
            for (lif = dlp->dl_lifs; lif != NULL && nlifs > 0;
                lif = lifnext, nlifs--) {
                lifnext = lif->lif_next;
                if (check_lif(lif, &msg.ifam, msglen)) {
                    dsmp->dsm_lif_wait--;
                    lif_finished = B_TRUE;
                }
            }
            if (dlp->dl_nlifs == 0) {
                remove_lease(dlp);
                lease_removed = B_TRUE;
            }
        }

        if ((isv6 && !check_main_lif(dsmp, &msg.ifam, msglen)) ||
            (!isv6 && !verify_lif(dsmp->dsm_lif))) {
            finished_smach(dsmp, DHCP_IPC_E_INVIF);
            continue;
        }

        /*
         * Ignore this state machine if nothing interesting has
         * happened.
         */
        if (!lif_finished && dsmp->dsm_lif_down == 0 &&
            (dsmp->dsm_leases != NULL || !lease_removed))
            continue;

        /*
         * If we're still waiting for DAD to complete on some of the
         * configured LIFs, then don't send a response.
         */
        if (dsmp->dsm_lif_wait != 0) {
            dhcpmsg(MSG_VERBOSE, "rtsock_event: %s still has %d "
                "LIFs waiting on DAD", dsmp->dsm_name,
                dsmp->dsm_lif_wait);
            continue;
        }

        /*
         * If we have some failed LIFs, then handle them now.  We'll
         * remove them from the list.  Any leases that become empty are
         * also removed as part of the decline-generation process.
         */
        if (dsmp->dsm_lif_down != 0)
            send_declines(dsmp);

        if (dsmp->dsm_leases == NULL) {
            dsmp->dsm_bad_offers++;
            /*
             * For DHCPv6, we'll process the restart once we're
             * done sending Decline messages, because these are
             * supposed to be acknowledged.  With DHCPv4, there's
             * no acknowledgment for a DECLINE, so after sending
             * it, we just restart right away.
             */
            if (!dsmp->dsm_isv6) {
                dhcpmsg(MSG_VERBOSE, "rtsock_event: %s has no "
                    "LIFs left", dsmp->dsm_name);
                dhcp_restart(dsmp);
            }
        } else {
            /*
             * If we're now up on at least some of the leases and
             * we were waiting for that, then kick off the rest of
             * configuration.  Lease validation and DAD are done.
             */
            dhcpmsg(MSG_VERBOSE, "rtsock_event: all LIFs verified "
                "on %s in %s state", dsmp->dsm_name,
                dhcp_state_to_string(oldstate));
            if (oldstate == PRE_BOUND ||
                oldstate == ADOPTING)
                dhcp_bound_complete(dsmp);
            if (oldstate == ADOPTING)
                dhcp_adopt_complete(dsmp);
        }
    }
}

/*
 * check_cmd_allowed(): check whether the requested command is allowed in the
 *          state specified.
 *
 *   input: DHCPSTATE: current state
 *      dhcp_ipc_type_t: requested command
 *  output: boolean_t: B_TRUE if command is allowed in this state
 */

boolean_t
check_cmd_allowed(DHCPSTATE state, dhcp_ipc_type_t cmd)
{
    return (ipc_cmd_allowed[state][cmd] != 0);
}

static boolean_t
is_iscsi_active(void)
{
    int fd;
    int active = 0;

    if ((fd = open(ISCSI_DRIVER_DEVCTL, O_RDONLY)) != -1) {
        if (ioctl(fd, ISCSI_IS_ACTIVE, &active) != 0)
            active = 0;
        (void) close(fd);
    }

    return (active != 0);
}