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

/*

 * Copyright (c) 2006, 2009 INRIA

 * Copyright (c) 2009 MIRKO BANCHI

 *

 * 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>

 * Author: Mirko Banchi <mk.banchi@gmail.com>

 */

#include "sta-wifi-mac.h"

#include "ns3/log.h"

#include "ns3/simulator.h"

#include "ns3/string.h"

#include "ns3/pointer.h"

#include "ns3/boolean.h"

#include "ns3/trace-source-accessor.h"

#include "qos-tag.h"

#include "mac-low.h"

#include "dcf-manager.h"

#include "mac-rx-middle.h"

#include "mac-tx-middle.h"

#include "wifi-mac-header.h"

#include "msdu-aggregator.h"

#include "amsdu-subframe-header.h"

#include "mgt-headers.h"

NS_LOG_COMPONENT_DEFINE ("StaWifiMac");

/*

 * The state machine for this STA is:

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

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

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

    \                                   \  /

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

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

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

                \                       ^

                 \                      |

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

                   \-> | Wait Probe Response |

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

 */

namespace ns3 {

NS_OBJECT_ENSURE_REGISTERED (StaWifiMac);

TypeId

StaWifiMac::GetTypeId (void)

{

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

    .SetParent<RegularWifiMac> ()

    .AddConstructor<StaWifiMac> ()

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

                   TimeValue (Seconds (0.05)),

                   MakeTimeAccessor (&StaWifiMac::m_probeRequestTimeout),

                   MakeTimeChecker ())

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

                   TimeValue (Seconds (0.5)),

                   MakeTimeAccessor (&StaWifiMac::m_assocRequestTimeout),

                   MakeTimeChecker ())

    .AddAttribute ("MaxMissedBeacons",

                   "Number of beacons which much be consecutively missed before "

                   "we attempt to restart association.",

                   UintegerValue (10),

                   MakeUintegerAccessor (&StaWifiMac::m_maxMissedBeacons),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("ActiveProbing", "If true, we send probe requests. If false, we don't. NOTE: if more than one STA in your simulation is using active probing, you should enable it at a different simulation time for each STA, otherwise all the STAs will start sending probes at the same time resulting in collisions. See bug 1060 for more info.",

                   BooleanValue (false),

                   MakeBooleanAccessor (&StaWifiMac::SetActiveProbing),

                   MakeBooleanChecker ())

    .AddTraceSource ("Assoc", "Associated with an access point.",

                     MakeTraceSourceAccessor (&StaWifiMac::m_assocLogger))

    .AddTraceSource ("DeAssoc", "Association with an access point lost.",

                     MakeTraceSourceAccessor (&StaWifiMac::m_deAssocLogger))

  ;

  return tid;

}

StaWifiMac::StaWifiMac ()

  : m_state (BEACON_MISSED),

    m_probeRequestEvent (),

    m_assocRequestEvent (),

    m_beaconWatchdogEnd (Seconds (0.0))

{

  NS_LOG_FUNCTION (this);

  // Let the lower layers know that we are acting as a non-AP STA in

  // an infrastructure BSS.

  SetTypeOfStation (STA);

}

StaWifiMac::~StaWifiMac ()

{

  NS_LOG_FUNCTION (this);

}

void

StaWifiMac::SetMaxMissedBeacons (uint32_t missed)

{

  NS_LOG_FUNCTION (this << missed);

  m_maxMissedBeacons = missed;

}

void

StaWifiMac::SetProbeRequestTimeout (Time timeout)

{

  NS_LOG_FUNCTION (this << timeout);

  m_probeRequestTimeout = timeout;

}

void

StaWifiMac::SetAssocRequestTimeout (Time timeout)

{

  NS_LOG_FUNCTION (this << timeout);

  m_assocRequestTimeout = timeout;

}

void

StaWifiMac::StartActiveAssociation (void)

{

  NS_LOG_FUNCTION (this);

  TryToEnsureAssociated ();

}

void

StaWifiMac::SetActiveProbing (bool enable)

{

  NS_LOG_FUNCTION (this << enable);

  if (enable)

    {

      Simulator::ScheduleNow (&StaWifiMac::TryToEnsureAssociated, this);

    }

  else

    {

      m_probeRequestEvent.Cancel ();

    }

}

void

StaWifiMac::SendProbeRequest (void)

{

  NS_LOG_FUNCTION (this);

  WifiMacHeader hdr;

  hdr.SetProbeReq ();

  hdr.SetAddr1 (Mac48Address::GetBroadcast ());

  hdr.SetAddr2 (GetAddress ());

  hdr.SetAddr3 (Mac48Address::GetBroadcast ());

  hdr.SetDsNotFrom ();

  hdr.SetDsNotTo ();

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

  MgtProbeRequestHeader probe;

  probe.SetSsid (GetSsid ());

  probe.SetSupportedRates (GetSupportedRates ());

  packet->AddHeader (probe);

  // The standard is not clear on the correct queue for management

  // frames if we are a QoS AP. The approach taken here is to always

  // use the DCF for these regardless of whether we have a QoS

  // association or not.

  m_dca->Queue (packet, hdr);

  m_probeRequestEvent = Simulator::Schedule (m_probeRequestTimeout,

                                             &StaWifiMac::ProbeRequestTimeout, this);

}

void

StaWifiMac::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);

  // The standard is not clear on the correct queue for management

  // frames if we are a QoS AP. The approach taken here is to always

  // use the DCF for these regardless of whether we have a QoS

  // association or not.

  m_dca->Queue (packet, hdr);

  m_assocRequestEvent = Simulator::Schedule (m_assocRequestTimeout,

                                             &StaWifiMac::AssocRequestTimeout, this);

}

void

StaWifiMac::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 ();

      SetState (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

StaWifiMac::AssocRequestTimeout (void)

{

  NS_LOG_FUNCTION (this);

  SetState (WAIT_ASSOC_RESP);

  SendAssociationRequest ();

}

void

StaWifiMac::ProbeRequestTimeout (void)

{

  NS_LOG_FUNCTION (this);

  SetState (WAIT_PROBE_RESP);

  SendProbeRequest ();

}

void

StaWifiMac::MissedBeacons (void)

{

  NS_LOG_FUNCTION (this);

  if (m_beaconWatchdogEnd > Simulator::Now ())

    {

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

                                              &StaWifiMac::MissedBeacons, this);

      return;

    }

  NS_LOG_DEBUG ("beacon missed");

  SetState (BEACON_MISSED);

  TryToEnsureAssociated ();

}

void

StaWifiMac::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, &StaWifiMac::MissedBeacons, this);

    }

}

bool

StaWifiMac::IsAssociated (void) const

{

  return m_state == ASSOCIATED;

}

bool

StaWifiMac::IsWaitAssocResp (void) const

{

  return m_state == WAIT_ASSOC_RESP;

}

void

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

{

  NS_LOG_FUNCTION (this << packet << to);

  if (!IsAssociated ())

    {

      NotifyTxDrop (packet);

      TryToEnsureAssociated ();

      return;

    }

  WifiMacHeader hdr;

  // If we are not a QoS AP then we definitely want to use AC_BE to

  // transmit the packet. A TID of zero will map to AC_BE (through \c

  // QosUtilsMapTidToAc()), so we use that as our default here.

  uint8_t tid = 0;

  // For now, an AP that supports QoS does not support non-QoS

  // associations, and vice versa. In future the AP model should

  // support simultaneously associated QoS and non-QoS STAs, at which

  // point there will need to be per-association QoS state maintained

  // by the association state machine, and consulted here.

  if (m_qosSupported)

    {

      hdr.SetType (WIFI_MAC_QOSDATA);

      hdr.SetQosAckPolicy (WifiMacHeader::NORMAL_ACK);

      hdr.SetQosNoEosp ();

      hdr.SetQosNoAmsdu ();

      // Transmission of multiple frames in the same TXOP is not

      // supported for now

      hdr.SetQosTxopLimit (0);

      // Fill in the QoS control field in the MAC header

      tid = QosUtilsGetTidForPacket (packet);

      // Any value greater than 7 is invalid and likely indicates that

      // the packet had no QoS tag, so we revert to zero, which'll

      // mean that AC_BE is used.

      if (tid >= 7)

        {

          tid = 0;

        }

      hdr.SetQosTid (tid);

    }

  else

    {

      hdr.SetTypeData ();

    }

  hdr.SetAddr1 (GetBssid ());

  hdr.SetAddr2 (m_low->GetAddress ());

  hdr.SetAddr3 (to);

  hdr.SetDsNotFrom ();

  hdr.SetDsTo ();

  if (m_qosSupported)

    {

      // Sanity check that the TID is valid

      NS_ASSERT (tid < 8);

      m_edca[QosUtilsMapTidToAc (tid)]->Queue (packet, hdr);

    }

  else

    {

      m_dca->Queue (packet, hdr);

    }

}

void

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

{

  NS_LOG_FUNCTION (this << packet << hdr);

  NS_ASSERT (!hdr->IsCtl ());

  if (hdr->GetAddr3 () == GetAddress ())

    {

      NS_LOG_LOGIC ("packet sent by us.");

      return;

    }

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

           && !hdr->GetAddr1 ().IsGroup ())

    {

      NS_LOG_LOGIC ("packet is not for us");

      NotifyRxDrop (packet);

      return;

    }

  else if (hdr->IsData ())

    {

      if (!IsAssociated ())

        {

          NS_LOG_LOGIC ("Received data frame while not associated: ignore");

          NotifyRxDrop (packet);

          return;

        }

      if (!(hdr->IsFromDs () && !hdr->IsToDs ()))

        {

          NS_LOG_LOGIC ("Received data frame not from the DS: ignore");

          NotifyRxDrop (packet);

          return;

        }

      if (hdr->GetAddr2 () != GetBssid ())

        {

          NS_LOG_LOGIC ("Received data frame not from the BSS we are associated with: ignore");

          NotifyRxDrop (packet);

          return;

        }

      if (hdr->IsQosData ())

        {

          if (hdr->IsQosAmsdu ())

            {

              NS_ASSERT (hdr->GetAddr3 () == GetBssid ());

              DeaggregateAmsduAndForward (packet, hdr);

              packet = 0;

            }

          else

            {

              ForwardUp (packet, hdr->GetAddr3 (), hdr->GetAddr1 ());

            }

        }

      else

        {

          ForwardUp (packet, hdr->GetAddr3 (), hdr->GetAddr1 ());

        }

      return;

    }

  else if (hdr->IsProbeReq ()

           || hdr->IsAssocReq ())

    {

      // This is a frame aimed at an AP, so we can safely ignore it.

      NotifyRxDrop (packet);

      return;

    }

  else if (hdr->IsBeacon ())

    {

      MgtBeaconHeader beacon;

      packet->RemoveHeader (beacon);

      bool goodBeacon = false;

      if (GetSsid ().IsBroadcast ()

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

        {

          goodBeacon = true;

        }

      if ((IsWaitAssocResp () || IsAssociated ()) && hdr->GetAddr3 () != GetBssid ())

        {

          goodBeacon = false;

        }

      if (goodBeacon)

        {

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

          RestartBeaconWatchdog (delay);

          SetBssid (hdr->GetAddr3 ());

        }

      if (goodBeacon && m_state == BEACON_MISSED)

        {

          SetState (WAIT_ASSOC_RESP);

          SendAssociationRequest ();

        }

      return;

    }

  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;

            }