/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2005,2006 INRIA

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as 

 * published by the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#include "ns3/packet.h"

#include "ns3/simulator.h"

#include "ns3/assert.h"

#include "ns3/log.h"

#include "ns3/node.h"

#include "ns3/uinteger.h"

#include "nqsta-wifi-mac.h"

#include "wifi-mac-header.h"

#include "mgt-headers.h"

#include "wifi-phy.h"

#include "dca-txop.h"

#include "mac-low.h"

#include "dcf-manager.h"

#include "mac-rx-middle.h"

NS_LOG_COMPONENT_DEFINE ("NqstaWifiMac");

/*

 * The state machine for this NQSTA is:

 --------------                                          -----------

 | Associated |   <--------------------      ------->    | Refused |

 --------------                        \    /            -----------

    \                                   \  /

     \    -----------------     -----------------------------

      \-> | Beacon Missed | --> | Wait Association Response |

          -----------------     -----------------------------

	        \                       ^

		 \                      |

		  \    -----------------------

	           \-> | Wait Probe Response |

		       -----------------------

 */

namespace ns3 {

NS_OBJECT_ENSURE_REGISTERED (NqstaWifiMac);

TypeId 

NqstaWifiMac::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::NqstaWifiMac")

    .SetParent<WifiMac> ()

    .AddConstructor<NqstaWifiMac> ()

    .AddAttribute ("ProbeRequestTimeout", "The interval between two consecutive probe request attempts.",

                   TimeValue (Seconds (0.05)),

                   MakeTimeAccessor (&NqstaWifiMac::m_probeRequestTimeout),

                   MakeTimeChecker ())

    .AddAttribute ("AssocRequestTimeout", "The interval between two consecutive assoc request attempts.",

                   TimeValue (Seconds (0.5)),

                   MakeTimeAccessor (&NqstaWifiMac::m_assocRequestTimeout),

                   MakeTimeChecker ())

    .AddAttribute ("MaxMissedBeacons", 

                   "Number of beacons which much be consecutively missed before "

                   "we attempt to restart association.",

                   UintegerValue (10),

                   MakeUintegerAccessor (&NqstaWifiMac::m_maxMissedBeacons),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("ActiveProbing", "If true, we send probe requests. If false, we don't.",

                   BooleanValue (false),

                   MakeBooleanAccessor (&NqstaWifiMac::SetActiveProbing),

                   MakeBooleanChecker ())

    ;

  return tid;

}

NqstaWifiMac::NqstaWifiMac ()

  : m_state (BEACON_MISSED),

    m_probeRequestEvent (),

    m_assocRequestEvent (),

    m_beaconWatchdogEnd (Seconds (0.0))

{

  NS_LOG_FUNCTION (this);

  m_rxMiddle = new MacRxMiddle ();

  m_rxMiddle->SetForwardCallback (MakeCallback (&NqstaWifiMac::Receive, this));

  m_low = CreateObject<MacLow> ();

  m_low->SetRxCallback (MakeCallback (&MacRxMiddle::Receive, m_rxMiddle));

  m_low->SetMac (this);

  m_dcfManager = new DcfManager ();

  m_dcfManager->SetupLowListener (m_low);

  m_dca = CreateObject<DcaTxop> ();

  m_dca->SetLow (m_low);

  m_dca->SetManager (m_dcfManager);

}

NqstaWifiMac::~NqstaWifiMac ()

{

  NS_LOG_FUNCTION (this);

}

void

NqstaWifiMac::DoDispose (void)

{

  NS_LOG_FUNCTION (this);

  delete m_rxMiddle;

  delete m_dcfManager;

  m_rxMiddle = 0;

  m_low = 0;

  m_dcfManager = 0;

  m_phy = 0;

  m_dca = 0;

  WifiMac::DoDispose ();

}

void 

NqstaWifiMac::SetSlot (Time slotTime)

{

  NS_LOG_FUNCTION (this << slotTime);

  m_dcfManager->SetSlot (slotTime);

  m_slot = slotTime;

}

void 

NqstaWifiMac::SetSifs (Time sifs)

{

  NS_LOG_FUNCTION (this << sifs);

  m_dcfManager->SetSifs (sifs);

  m_sifs = sifs;

}

void 

NqstaWifiMac::SetEifsNoDifs (Time eifsNoDifs)

{

  NS_LOG_FUNCTION (this << eifsNoDifs);

  m_dcfManager->SetEifsNoDifs (eifsNoDifs);

  m_eifsNoDifs = eifsNoDifs;

}

Time 

NqstaWifiMac::GetSlot (void) const

{

  return m_slot;

}

Time 

NqstaWifiMac::GetSifs (void) const

{

  return m_sifs;

}

Time 

NqstaWifiMac::GetEifsNoDifs (void) const

{

  return m_eifsNoDifs;

}

void 

NqstaWifiMac::SetWifiPhy (Ptr<WifiPhy> phy)

{

  m_phy = phy;

  m_dcfManager->SetupPhyListener (phy);

  m_low->SetPhy (phy);

}

void 

NqstaWifiMac::SetWifiRemoteStationManager (Ptr<WifiRemoteStationManager> stationManager)

{

  m_stationManager = stationManager;

  m_dca->SetWifiRemoteStationManager (stationManager);

  m_low->SetWifiRemoteStationManager (stationManager);

}

void 

NqstaWifiMac::SetForwardUpCallback (Callback<void,Ptr<Packet>, const Mac48Address &> upCallback)

{

  m_forwardUp = upCallback;

}

void 

NqstaWifiMac::SetLinkUpCallback (Callback<void> linkUp)

{

  m_linkUp = linkUp;

}

void 

NqstaWifiMac::SetLinkDownCallback (Callback<void> linkDown)

{

  m_linkDown = linkDown;

}

Mac48Address 

NqstaWifiMac::GetAddress (void) const

{

  return m_address;

}

Ssid 

NqstaWifiMac::GetSsid (void) const

{

  return m_ssid;

}

Mac48Address 

NqstaWifiMac::GetBssid (void) const

{

  return m_bssid;

}

void 

NqstaWifiMac::SetAddress (Mac48Address address)

{

  NS_LOG_FUNCTION (this << address);

  m_address = address;

}

void 

NqstaWifiMac::SetSsid (Ssid ssid)

{

  NS_LOG_FUNCTION (this << ssid);

  m_ssid = ssid;

}

void 

NqstaWifiMac::SetMaxMissedBeacons (uint32_t missed)

{

  NS_LOG_FUNCTION (this << missed);

  m_maxMissedBeacons = missed;

}

void 

NqstaWifiMac::SetProbeRequestTimeout (Time timeout)

{

  NS_LOG_FUNCTION (this << timeout);

  m_probeRequestTimeout = timeout;

}

void 

NqstaWifiMac::SetAssocRequestTimeout (Time timeout)

{

  NS_LOG_FUNCTION (this << timeout);

  m_assocRequestTimeout = timeout;

}

void 

NqstaWifiMac::StartActiveAssociation (void)

{

  NS_LOG_FUNCTION (this);

  TryToEnsureAssociated ();

}

Mac48Address

NqstaWifiMac::GetBroadcastBssid (void)

{

  return Mac48Address::GetBroadcast ();

}

void 

NqstaWifiMac::SetBssid (Mac48Address bssid)

{

  NS_LOG_FUNCTION (this << bssid);

  m_bssid = bssid;

}

void 

NqstaWifiMac::SetActiveProbing (bool enable)

{

  NS_LOG_FUNCTION (this << enable);

  if (enable)

    {

      TryToEnsureAssociated ();

    }

  else

    {

      m_probeRequestEvent.Cancel ();

    }

}

void 

NqstaWifiMac::ForwardUp (Ptr<Packet> packet, const Mac48Address &address)

{

  NS_LOG_FUNCTION (this << packet << address);

  m_forwardUp (packet, address);

}

void

NqstaWifiMac::SendProbeRequest (void)

{

  NS_LOG_FUNCTION (this);

  WifiMacHeader hdr;

  hdr.SetProbeReq ();

  hdr.SetAddr1 (GetBroadcastBssid ());

  hdr.SetAddr2 (GetAddress ());

  hdr.SetAddr3 (GetBroadcastBssid ());

  hdr.SetDsNotFrom ();

  hdr.SetDsNotTo ();

  Ptr<Packet> packet = Create<Packet> ();

  MgtProbeRequestHeader probe;

  probe.SetSsid (GetSsid ());

  probe.SetSupportedRates (GetSupportedRates ());

  packet->AddHeader (probe);

  m_dca->Queue (packet, hdr);

  m_probeRequestEvent = Simulator::Schedule (m_probeRequestTimeout,

                                             &NqstaWifiMac::ProbeRequestTimeout, this);

}

void

NqstaWifiMac::SendAssociationRequest (void)

{

  NS_LOG_FUNCTION (this << GetBssid ());

  WifiMacHeader hdr;

  hdr.SetAssocReq ();

  hdr.SetAddr1 (GetBssid ());

  hdr.SetAddr2 (GetAddress ());

  hdr.SetAddr3 (GetBssid ());

  hdr.SetDsNotFrom ();

  hdr.SetDsNotTo ();

  Ptr<Packet> packet = Create<Packet> ();

  MgtAssocRequestHeader assoc;

  assoc.SetSsid (GetSsid ());

  assoc.SetSupportedRates (GetSupportedRates ());

  packet->AddHeader (assoc);

  m_dca->Queue (packet, hdr);

  m_assocRequestEvent = Simulator::Schedule (m_assocRequestTimeout,

                                             &NqstaWifiMac::AssocRequestTimeout, this);

}

void

NqstaWifiMac::TryToEnsureAssociated (void)

{

  NS_LOG_FUNCTION (this);

  switch (m_state) {

  case ASSOCIATED:

    return;

    break;

  case WAIT_PROBE_RESP:

    /* we have sent a probe request earlier so we

       do not need to re-send a probe request immediately.

       We just need to wait until probe-request-timeout

       or until we get a probe response

     */

    break;

  case BEACON_MISSED:

    /* we were associated but we missed a bunch of beacons

     * so we should assume we are not associated anymore.

     * We try to initiate a probe request now.

     */

    m_linkDown ();

    m_state = WAIT_PROBE_RESP;

    SendProbeRequest ();

    break;

  case WAIT_ASSOC_RESP:

    /* we have sent an assoc request so we do not need to

       re-send an assoc request right now. We just need to

       wait until either assoc-request-timeout or until

       we get an assoc response.

     */

    break;

  case REFUSED:

    /* we have sent an assoc request and received a negative

       assoc resp. We wait until someone restarts an 

       association with a given ssid.

     */

    break;

  }

}

void

NqstaWifiMac::AssocRequestTimeout (void)

{

  NS_LOG_FUNCTION (this);

  m_state = WAIT_ASSOC_RESP;

  SendAssociationRequest ();

}

void

NqstaWifiMac::ProbeRequestTimeout (void)

{

  NS_LOG_FUNCTION (this);

  m_state = WAIT_PROBE_RESP;

  SendProbeRequest ();

}

void 

NqstaWifiMac::MissedBeacons (void)

{

  NS_LOG_FUNCTION (this);

  if (m_beaconWatchdogEnd > Simulator::Now ())

    {

      m_beaconWatchdog = Simulator::Schedule (m_beaconWatchdogEnd - Simulator::Now (),

                                              &NqstaWifiMac::MissedBeacons, this);

      return;

    }

  NS_LOG_DEBUG ("beacon missed");

  m_state = BEACON_MISSED;

  TryToEnsureAssociated ();

}

void 

NqstaWifiMac::RestartBeaconWatchdog (Time delay)

{

  NS_LOG_FUNCTION (this << delay);

  m_beaconWatchdogEnd = std::max (Simulator::Now () + delay, m_beaconWatchdogEnd);

  if (Simulator::GetDelayLeft (m_beaconWatchdog) < delay &&

      m_beaconWatchdog.IsExpired ())

    {

      NS_LOG_DEBUG ("really restart watchdog.");

      m_beaconWatchdog = Simulator::Schedule (delay, &NqstaWifiMac::MissedBeacons, this);

    }

}

bool

NqstaWifiMac::IsAssociated (void)

{

  return (m_state == ASSOCIATED)?true:false;

}

void 

NqstaWifiMac::Enqueue (Ptr<const Packet> packet, Mac48Address to, Mac48Address from)

{

  NS_LOG_FUNCTION (this << packet << to);

  if (!IsAssociated ()) 

    {

      TryToEnsureAssociated ();

      return;

    }

  //NS_LOG_DEBUG ("enqueue size="<<packet->GetSize ()<<", to="<<to);

  WifiMacHeader hdr;

  hdr.SetTypeData ();

  hdr.SetAddr1 (GetBssid ());

  hdr.SetAddr2 (from);

  hdr.SetAddr3 (to);

  hdr.SetDsNotFrom ();

  hdr.SetDsTo ();

  m_dca->Queue (packet, hdr);

}

void 

NqstaWifiMac::Receive (Ptr<Packet> packet, WifiMacHeader const *hdr)

{

  NS_LOG_FUNCTION (this << packet << hdr);

  NS_ASSERT (!hdr->IsCtl ());

  if (hdr->GetAddr1 () != GetAddress () &&

      !hdr->GetAddr1 ().IsBroadcast ()) 

    {

      // packet is not for us

    } 

  else if (hdr->IsData ()) 

    {

      ForwardUp (packet, hdr->GetAddr2 ());

    } 

  else if (hdr->IsProbeReq () ||

           hdr->IsAssocReq ()) 

    {

      /* this is a frame aimed at an AP.

       * so we can safely ignore it.

       */

    } 

  else if (hdr->IsBeacon ()) 

    {

      MgtBeaconHeader beacon;

      packet->RemoveHeader (beacon);

      bool goodBeacon = false;

      if (GetSsid ().IsBroadcast () ||

          beacon.GetSsid ().IsEqual (GetSsid ()))

        {

          Time delay = MicroSeconds (beacon.GetBeaconIntervalUs () * m_maxMissedBeacons);

          RestartBeaconWatchdog (delay);

          goodBeacon = true;

        }

      if (goodBeacon) 

        {

          SetBssid (hdr->GetAddr3 ());

        }

      if (goodBeacon && m_state == BEACON_MISSED) 

        {

          m_state = WAIT_ASSOC_RESP;

          SendAssociationRequest ();

        }

  } 

  else if (hdr->IsProbeResp ()) 

    {

      if (m_state == WAIT_PROBE_RESP) 

        {

          MgtProbeResponseHeader probeResp;

          packet->RemoveHeader (probeResp);

          if (!probeResp.GetSsid ().IsEqual (GetSsid ()))

            {

              //not a probe resp for our ssid.

              return;

            }

          SetBssid (hdr->GetAddr3 ());

          Time delay = MicroSeconds (probeResp.GetBeaconIntervalUs () * m_maxMissedBeacons);

          RestartBeaconWatchdog (delay);