/*
 * 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.
 * Copyright (c) 2016-2017, Chris Fraire <cfraire@me.com>.
 */

#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 <dhcp_inittab.h>
#include <dhcp_symbol.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;
static void dhcp_smach_set_msg_reqhost(dhcp_smach_t *dsmp,
                ipc_action_t *iap);
static DHCP_OPT * dhcp_get_ack_or_state(const dhcp_smach_t *dsmp,
                const PKT_LIST *plp, uint_t codenum, boolean_t *did_alloc);

/*
 * 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 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:
                dhcp_smach_set_msg_reqhost(dsmp, iap);
                (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 {
                                opt = dhcp_get_ack_or_state(dsmp, ack,
                                    optnum.code, &did_alloc);
                        }
                        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;

                                opt = malloc(optnum.size + DHCP_OPT_META_LEN);
                                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.
                 */

                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 +
                                    DHCP_OPT_META_LEN;
                        }
                        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);
                dhcp_smach_set_msg_reqhost(dsmp, iap);

                /*
                 * 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)) {
                        dhcp_selecting(dsmp);
                        /* next destination: dhcp_requesting() */
                }
                /* else next destination: dhcp_start() */
        }
        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;
        }
        }
}

/*
 * dhcp_smach_set_msg_reqhost(): set dsm_msg_reqhost based on the message
 * content of a DHCP IPC message
 *
 *   input: dhcp_smach_t *: the state machine instance;
 *          ipc_action_t *: the decoded DHCP IPC message;
 *  output: void
 */

static void
dhcp_smach_set_msg_reqhost(dhcp_smach_t *dsmp, ipc_action_t *iap)
{
        DHCP_OPT        *d4o;
        dhcp_symbol_t   *entry;
        char            *value;

        if (dsmp->dsm_msg_reqhost != NULL) {
                dhcpmsg(MSG_DEBUG,
                    "dhcp_smach_set_msg_reqhost: nullify former value, %s",
                    dsmp->dsm_msg_reqhost);
                free(dsmp->dsm_msg_reqhost);
                dsmp->dsm_msg_reqhost = NULL;
        }

        /*
         * if a STANDARD/HOSTNAME was sent in the IPC request, then copy that
         * value into the state machine data if decoding succeeds. Otherwise,
         * log to indicate at what step the decoding stopped.
         */

        if (dsmp->dsm_isv6) {
                dhcpmsg(MSG_DEBUG, "dhcp_smach_set_msg_reqhost: ipv6 is not"
                    " handled");
                return;
        } else if (iap->ia_request->data_type != DHCP_TYPE_OPTION) {
                dhcpmsg(MSG_DEBUG, "dhcp_smach_set_msg_reqhost: request type"
                    " %d is not DHCP_TYPE_OPTION", iap->ia_request->data_type);
                return;
        }

        if (iap->ia_request->data_length <= DHCP_OPT_META_LEN) {
                dhcpmsg(MSG_WARNING, "dhcp_smach_set_msg_reqhost:"
                    " DHCP_TYPE_OPTION ia_request buffer is short");
                return;
        }

        d4o = (DHCP_OPT *)iap->ia_request->buffer;
        if (d4o->code != CD_HOSTNAME) {
                dhcpmsg(MSG_DEBUG,
                    "dhcp_smach_set_msg_reqhost: ignoring DHCPv4"
                    " option %u", d4o->code);
                return;
        } else if (iap->ia_request->data_length - DHCP_OPT_META_LEN
            != d4o->len) {
                dhcpmsg(MSG_WARNING, "dhcp_smach_set_msg_reqhost:"
                    " unexpected DHCP_OPT buffer length %u for CD_HOSTNAME"
                    " option length %u", iap->ia_request->data_length,
                    d4o->len);
                return;
        }

        entry = inittab_getbycode(ITAB_CAT_STANDARD, ITAB_CONS_INFO,
            CD_HOSTNAME);
        if (entry == NULL) {
                dhcpmsg(MSG_WARNING,
                    "dhcp_smach_set_msg_reqhost: error getting"
                    " ITAB_CAT_STANDARD ITAB_CONS_INFO"
                    " CD_HOSTNAME entry");
                return;
        }

        value = inittab_decode(entry, d4o->value, d4o->len,
            /* just_payload */ B_TRUE);
        if (value == NULL) {
                dhcpmsg(MSG_WARNING,
                    "dhcp_smach_set_msg_reqhost: error decoding"
                    " CD_HOSTNAME value from DHCP_OPT");
        } else {
                dhcpmsg(MSG_DEBUG,
                    "dhcp_smach_set_msg_reqhost: host %s", value);
                free(dsmp->dsm_msg_reqhost);
                dsmp->dsm_msg_reqhost = value;
        }
        free(entry);
}

/*
 * dhcp_get_ack_or_state(): get a v4 option from the ACK or from the state
 * machine state for certain codes that are not ACKed (e.g., CD_CLIENT_ID)
 *
 *   input: dhcp_smach_t *: the state machine instance;
 *          PKT_LIST *: the decoded DHCP IPC message;
 *          uint_t: the DHCP client option code;
 *          boolean_t *: a pointer to a value that will be set to B_TRUE if
 *              the return value must be freed (or else set to B_FALSE);
 *  output: the option if found or else NULL.
 */

static DHCP_OPT *
dhcp_get_ack_or_state(const dhcp_smach_t *dsmp, const PKT_LIST *plp,
    uint_t codenum, boolean_t *did_alloc)
{
        DHCP_OPT *opt;

        *did_alloc = B_FALSE;

        if (codenum > DHCP_LAST_OPT)
                return (NULL);

        /* check the ACK first for all codes */
        opt = plp->opts[codenum];
        if (opt != NULL)
                return (opt);

        /* check the machine state also for certain codes */
        switch (codenum) {
        case CD_CLIENT_ID:
                /*
                 * CD_CLIENT_ID is not sent in an ACK, but it's possibly
                 * available from the state machine data
                 */

                if (dsmp->dsm_cidlen > 0) {
                        if ((opt = malloc(dsmp->dsm_cidlen + DHCP_OPT_META_LEN))
                            != NULL) {
                                *did_alloc = B_TRUE;
                                (void) encode_dhcp_opt(opt,
                                    B_FALSE /* is IPv6 */, CD_CLIENT_ID,
                                    dsmp->dsm_cid, dsmp->dsm_cidlen);
                        }
                }
                break;
        default:
                break;
        }
        return (opt);
}

/*
 * 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);
}