dhcpcstate2.c

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*
* This routine sends a timeout notification to the client monitor task when 
* the interval for receiving a server reply to a renewal request expires. It
* is called at interrupt level by a watchdog timer. The monitor task will 
* eventually execute the RENEWING state to process the timeout event and
* retransmit the DHCP request message.
*
* RETURNS: N/A
*
* ERRNO: N/A
*
* NOMANUAL
*/

void retrans_renewing
    (
    LEASE_DATA * 	pLeaseData 	/* lease-specific status information */
    )
    {
    /*
     * Ignore the timeout if a state transition occurred
     * before processing completed.
     */

    if (pLeaseData->currState != RENEWING)
        return;

    /* Construct and send a timeout message to the lease monitor task. */

    dhcpcEventAdd (DHCP_AUTO_EVENT, DHCP_TIMEOUT, pLeaseData, TRUE);

    return;
    }

/*******************************************************************************
*
* retrans_rebinding - signal when reception interval for rebind offer expires
*
* This routine sends a timeout notification to the client monitor task when 
* the interval for receiving a lease offer from a different server expires. It
* is called at interrupt level by a watchdog timer. The monitor task will 
* eventually execute the REBINDING state to process the timeout event and
* retransmit the DHCP discover message.
*
* RETURNS: N/A
*
* ERRNO: N/A
*
* NOMANUAL
*/

void retrans_rebinding
    (
    LEASE_DATA * 	pLeaseData 	/* lease-specific status information */
    )
    {
    /*
     * Ignore the timeout if a state transition occurred
     * before processing completed.
     */

    if (pLeaseData->currState != REBINDING)
        return;

    /* Construct and send a timeout message to the lease monitor task. */

    dhcpcEventAdd (DHCP_AUTO_EVENT, DHCP_TIMEOUT, pLeaseData, TRUE);

    return;
    }

/*******************************************************************************
*
* retrans_reboot_verify - retransmission in rebooting state
*
* This routine signals the DHCP client monitor task when the timeout interval 
* for receiving a server reply expires for the lease indicated by the 
* <pLeaseData> parameter. The client monitor task will pass the event to the 
* reboot_verify() routine in the finite state machine.
* retrans_reboot_verify - signal when verification reception interval expires
*
* This routine sends a timeout notification to the client monitor task when 
* the interval for receiving a server reply to a reboot (or verify) request 
* expires. It is called at interrupt level by a watchdog timer. The monitor 
* task will eventually execute the REBOOTING or VERIFYING state to process 
* the timeout event and retransmit the appropriate DHCP request message.
*
* RETURNS: N/A
*
* ERRNO: N/A
*
* NOMANUAL
*/

void retrans_reboot_verify
    (
    LEASE_DATA * 	pLeaseData 	/* lease-specific status information */
    )
    {
    /*
     * Ignore the timeout if a state transition occurred
     * before processing completed.
     */

    if (pLeaseData->currState != REBOOTING &&
            pLeaseData->currState != VERIFYING)
        return;

    /* Construct and send a timeout message to the lease monitor task. */

    dhcpcEventAdd (DHCP_AUTO_EVENT, DHCP_TIMEOUT, pLeaseData, TRUE);

    return;
    }

/*******************************************************************************
*
* bound - Active state of client finite state machine
*
* This routine contains the fourth state of the client finite state machine.
* It accepts and services all user requests for BOOTP and infinite DHCP leases
* throughout their lifetimes. For finite DHCP leases, it handles all processing
* until one of the lease timers expires. At that point, processing continues 
* with the renewing() or rebinding() routines.
* .IP
* This routine is invoked by the event handler of the client monitor task,
* and should only be called internally. Any arriving DHCP messages contain
* stale offers or responses and are discarded. User requests generated
* by calls to the dhcpcRelease() and dhcpcVerify() routines are accepted.
*
* RETURNS: OK (processing complete), DHCPC_DONE (remove lease),
*          DHCPC_MORE (continue), or ERROR.
*
* ERRNO: N/A
*
* NOMANUAL
*/

int bound
    (
    EVENT_DATA * 	pEvent 	/* pointer to event descriptor */
    )
    {
    int timeout;    /* Epoch when intermediate lease timers expire. */
    int limit;      /* Epoch when lease expires. */
   
    LEASE_DATA * 	pLeaseData;
    int status;

    time_t curr_epoch = 0;

    /*
     * Use the cookie to access the lease-specific data structures. For now,
     * just typecast the cookie. This translation could be replaced with a more
     * sophisticated lookup at some point.
     */

    pLeaseData = (LEASE_DATA *)pEvent->leaseId;

    /* 
     * Process events for BOOTP and infinite DHCP leases. Timeouts and
     * incoming messages should never occur for either type of lease. Also,
     * BOOTP leases require no special processing in response to user requests
     * for verification or shutdown.
     */
     
    if (pLeaseData->dhcpcParam->lease_duration == ~0)
        {
        /* Ignore timeouts and received DHCP messages. */

        if (pEvent->source != DHCP_AUTO_EVENT) 
            {
            /* Process user requests. */

            if (pEvent->type == DHCP_USER_RELEASE)    /* Relinquish lease. */
                {
                if (pLeaseData->leaseType != DHCP_BOOTP)
                    release (pLeaseData);  
                return (DHCPC_DONE);
                }
            if (pEvent->type == DHCP_USER_VERIFY)    /* Verify lease. */
                {
                if (pLeaseData->leaseType != DHCP_BOOTP)
                    {
                    /* Set the lease data to execute verify() routine. */

                    pLeaseData->prevState = BOUND;
                    pLeaseData->currState = VERIFY;

                    return (DHCPC_MORE);
                    }
                }
            }
        return (OK);
        }

    /* The rest of the routine handles processing for finite DHCP leases. */

    bzero (sbuf.buf, sbuf.size + DHCPC_OFF);

    if (time (&curr_epoch) == -1) 
        {
#ifdef DHCPC_DEBUG
        logMsg ("time() error in bound()\n", 0, 0, 0, 0, 0, 0);
#endif
        return (ERROR);
        }

    if (pLeaseData->prevState != BOUND)
        {
        /* 
         * The interval between lease acknowledgement and the entry to the 
         * bound() routine depends on the workload of the client monitor task 
         * and is completely unpredictable. Check all lease timers, since they 
         * might have expired during that time.
         */

        wdCancel (pLeaseData->timer);

#ifdef DHCPC_DEBUG
        logMsg ("dhcpc: Entering BOUND state.\n", 0, 0, 0, 0, 0, 0);
#endif
        timeout = pLeaseData->dhcpcParam->lease_origin + 
                      pLeaseData->dhcpcParam->dhcp_t2;
        limit = pLeaseData->dhcpcParam->lease_origin + 
                    pLeaseData->dhcpcParam->lease_duration;

        if (curr_epoch >= limit || timeout <= curr_epoch)
            {
            /* Lease or second timer expired - create a timeout event. */

            pEvent->source = DHCP_AUTO_EVENT;
            pEvent->type = DHCP_TIMEOUT;
            }
        else
            {
            timeout =  pLeaseData->dhcpcParam->lease_origin + 
                           pLeaseData->dhcpcParam->dhcp_t1;
            if (timeout <= curr_epoch)
                {
                /* First timer expired - create a timeout event. */

                pEvent->source = DHCP_AUTO_EVENT;
                pEvent->type = DHCP_TIMEOUT;
                }
            else
                {
                /* No timers expired - set to time remaining with T1. */

                timeout = pLeaseData->dhcpcParam->lease_origin + 
                              pLeaseData->dhcpcParam->dhcp_t1 - curr_epoch;
                wdStart (pLeaseData->timer, sysClkRateGet() * timeout,
                         (FUNCPTR)alarm_bound, (int)pLeaseData);
                }
            }
        pLeaseData->prevState = BOUND;

#ifdef DHCPC_DEBUG
        logMsg ("dhcpc: Ready for user requests.\n", 0, 0, 0, 0, 0, 0); 
#endif
        }

    if (pEvent->type == DHCPC_STATE_BEGIN)   /* Initial processing finished. */
        return (OK);

    if (pEvent->source == DHCP_AUTO_EVENT)
        {
        /* If no timers have expired, ignore received DHCP messages. */

        if (pEvent->type == DHCP_MSG_ARRIVED)
            return (OK);
        else
            {
            /*
             * Initiate renewal or rebinding when lease timers expire.
             * If the client monitor task is overloaded, processing may
             * occur well after the event notification is received.
             * In the worst case, the lease could expire before any
             * processing is performed. The timers can also expire
             * during a requested lease verification. Excess timeout 
             * notifications which might be present from earlier states 
             * are ignored.
             */

            limit = pLeaseData->dhcpcParam->lease_origin + 
                        pLeaseData->dhcpcParam->lease_duration;
            if (curr_epoch >= limit)
                {
                /* Lease expired between notification and processing. */

                pLeaseData->prevState = REQUESTING;
                pLeaseData->currState = INIT;
                return (DHCPC_MORE);
                }

            timeout = pLeaseData->dhcpcParam->lease_origin +
                          pLeaseData->dhcpcParam->dhcp_t2;
            if (timeout <= curr_epoch && curr_epoch < limit)
                {
                /* Second timer expired: contact any server for parameters. */

#ifdef DHCPC_DEBUG
                logMsg ("Entering REBINDING state.\n", 0, 0, 0, 0, 0, 0);
#endif
                make_request (pLeaseData, REBINDING, TRUE);
                dhcpcMsgOut.udp->uh_sum = 0;
                dhcpcMsgOut.udp->uh_sum = udp_cksum (&spudph, 
                                                     (char *)dhcpcMsgOut.udp,
                                                     ntohs (spudph.ulen));
                if (etherOutput (pLeaseData->ifData.iface, dhcpcMsgOut.ether,
                         &sbuf.buf [DHCPC_OFF + ETHERHL], sbuf.size - ETHERHL)
                    == ERROR)
#ifdef DHCPC_DEBUG
                logMsg ("Can't send DHCPREQUEST(REBINDING)\n", 
                        0, 0, 0, 0, 0, 0);
#endif
                pLeaseData->prevState = BOUND;
                pLeaseData->currState = REBINDING;

                return (OK);
                }
            timeout = pLeaseData->dhcpcParam->lease_origin +
                          pLeaseData->dhcpcParam->dhcp_t1;
            limit = pLeaseData->dhcpcParam->lease_origin +
                        pLeaseData->dhcpcParam->dhcp_t2;
            if (timeout <= curr_epoch && curr_epoch < limit)
                {
                /*
                 * First timer expired: 
                 *    attempt to renew lease with current server.
                 */
#ifdef DHCPC_DEBUG
                logMsg ("Entering RENEWING state.\n", 0, 0, 0, 0, 0, 0);
#endif
                make_request (pLeaseData, RENEWING, TRUE);

                /* Ignore transmission failures for handling by timeout. */

                status = send_unicast (&pLeaseData->dhcpcParam->server_id, 
                                       dhcpcMsgOut.dhcp);
#ifdef DHCPC_DEBUG
                if (status < 0)
                    logMsg ("Can't send DHCPREQUEST(RENEWING)\n.", 
                            0, 0, 0, 0, 0, 0);
#endif

                
                /* DHCP request sent. Set lease data to execute next state. */

                pLeaseData->prevState = BOUND;
                pLeaseData->currState = RENEWING;

                pLeaseData->initEpoch = curr_epoch;

                /*
                 * Set the retransmission timer to wait for one-half of the 
                 * remaining time before T2 expires, or 60 seconds if T2 
                 * expires in less than one minute.
                 */

                timeout = limit - curr_epoch;
                if (timeout > 60) 
                    timeout /= 2;
                else
                    timeout = 60;

                /* Set timer for retransmission of request message. */

                wdStart (pLeaseData->timer, sysClkRateGet() * timeout, 
                         (FUNCPTR)retrans_renewing, (int)pLeaseData);

                return (OK);
                }
            }    /* End of timeout processing. */
        }    /* End of automatic events. */
    else
        {
        /* Process user requests. */