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

/*

 * Copyright (c) 2007 Emmanuelle Laprise

 *

 * 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: Emmanuelle Laprise <emmanuelle.laprise@bluekazoo.ca>

 */

#include "ns3/log.h"

#include "ns3/queue.h"

#include "ns3/simulator.h"

#include "ns3/ethernet-header.h"

#include "ns3/ethernet-trailer.h"

#include "ns3/llc-snap-header.h"

#include "ns3/error-model.h"

#include "ns3/enum.h"

#include "ns3/boolean.h"

#include "ns3/uinteger.h"

#include "ns3/pointer.h"

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

#include "csma-net-device.h"

#include "csma-channel.h"

NS_LOG_COMPONENT_DEFINE ("CsmaNetDevice");

namespace ns3 {

NS_OBJECT_ENSURE_REGISTERED (CsmaNetDevice);

  TypeId 

CsmaNetDevice::GetTypeId (void)

{

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

    .SetParent<NetDevice> ()

    .AddConstructor<CsmaNetDevice> ()

    .AddAttribute ("Address", 

                   "The MAC address of this device.",

                   Mac48AddressValue (Mac48Address ("ff:ff:ff:ff:ff:ff")),

                   MakeMac48AddressAccessor (&CsmaNetDevice::m_address),

                   MakeMac48AddressChecker ())

    .AddAttribute ("FrameSize", 

                   "The maximum size of a packet sent over this device.",

                   UintegerValue (DEFAULT_FRAME_SIZE),

                   MakeUintegerAccessor (&CsmaNetDevice::SetFrameSize,

                                         &CsmaNetDevice::GetFrameSize),

                   MakeUintegerChecker<uint16_t> ())

    .AddAttribute ("EncapsulationMode", 

                   "The link-layer encapsulation type to use.",

                   EnumValue (DIX),

                   MakeEnumAccessor (&CsmaNetDevice::SetEncapsulationMode),

                   MakeEnumChecker (DIX, "Dix",

                                    LLC, "Llc"))

    .AddAttribute ("SendEnable", 

                   "Enable or disable the transmitter section of the device.",

                   BooleanValue (true),

                   MakeBooleanAccessor (&CsmaNetDevice::m_sendEnable),

                   MakeBooleanChecker ())

    .AddAttribute ("ReceiveEnable",

                   "Enable or disable the receiver section of the device.",

                   BooleanValue (true),

                   MakeBooleanAccessor (&CsmaNetDevice::m_receiveEnable),

                   MakeBooleanChecker ())

                   "The receiver error model used to simulate packet loss",

                   PointerValue (),

                   MakePointerAccessor (&CsmaNetDevice::m_receiveErrorModel),

                   MakePointerChecker<ErrorModel> ())

    .AddAttribute ("TxQueue", 

                   "A queue to use as the transmit queue in the device.",

                   PointerValue (),

                   MakePointerAccessor (&CsmaNetDevice::m_queue),

                   MakePointerChecker<Queue> ())

    .AddTraceSource ("Rx", 

                     "The trace source to fire on reception of a MAC packet.",

                     MakeTraceSourceAccessor (&CsmaNetDevice::m_rxTrace))

    .AddTraceSource ("Drop", 

                     "Trace source to fire on when a MAC packet is dropped.",

                     MakeTraceSourceAccessor (&CsmaNetDevice::m_dropTrace))

    ;

  return tid;

}

CsmaNetDevice::CsmaNetDevice ()

  : m_name (""),

    m_linkUp (false)

{

  NS_LOG_FUNCTION (this);

  m_txMachineState = READY;

  m_tInterframeGap = Seconds (0);

  m_channel = 0; 

  // 

  // We would like to let the attribute system take care of initializing the packet encapsulation stuff, but we also don't want to

  // get caught up in initialization order changes.  So we'll get the three problem variables into a consistent state here before the

  // attribute calls, and then depend on the semantics of the setters to preserve a consistent state.  This really doesn't have to be

  // the same set of values as the initial values set by the attributes, but it does have to be a consistent set.  That is, you can

  // just change the ddfault encapsulation mode above without having to change it here.  We keep it the same for GP.

  //

  m_encapMode = DIX;

  m_frameSize = DEFAULT_FRAME_SIZE;

  m_mtu = MtuFromFrameSize (m_frameSize);

}

CsmaNetDevice::~CsmaNetDevice()

{

  NS_LOG_FUNCTION_NOARGS ();

  m_queue = 0;

}

  void 

CsmaNetDevice::DoDispose ()

{

  NS_LOG_FUNCTION_NOARGS ();

  m_channel = 0;

  m_node = 0;

  NetDevice::DoDispose ();

}

  uint32_t

CsmaNetDevice::MtuFromFrameSize (uint32_t frameSize)

{

  NS_LOG_FUNCTION (frameSize);

  NS_ASSERT_MSG (frameSize <= std::numeric_limits<uint16_t>::max (), 

                 "CsmaNetDevice::MtuFromFrameSize(): Frame size should be derived from 16-bit quantity: " << frameSize);

  uint32_t newSize;

  switch (m_encapMode) 

    {

    case DIX:

      newSize = frameSize - ETHERNET_OVERHEAD;

      break;

    case LLC: 

      {

        LlcSnapHeader llc;

        NS_ASSERT_MSG ((uint32_t)(frameSize - ETHERNET_OVERHEAD) >= llc.GetSerializedSize (), 

                       "CsmaNetDevice::MtuFromFrameSize(): Given frame size too small to support LLC mode");

        newSize = frameSize - ETHERNET_OVERHEAD - llc.GetSerializedSize ();

      }

      break;

    case ILLEGAL:

    default:

      NS_FATAL_ERROR ("CsmaNetDevice::MtuFromFrameSize(): Unknown packet encapsulation mode");

      return 0;

    }

  return newSize;

}

  uint32_t

CsmaNetDevice::FrameSizeFromMtu (uint32_t mtu)

{

  NS_LOG_FUNCTION (mtu);

  uint32_t newSize;

  switch (m_encapMode) 

    {

    case DIX:

      newSize = mtu + ETHERNET_OVERHEAD;

      break;

    case LLC: 

      {

        LlcSnapHeader llc;

        newSize = mtu + ETHERNET_OVERHEAD + llc.GetSerializedSize ();

      }

      break;

    case ILLEGAL:

    default:

      NS_FATAL_ERROR ("CsmaNetDevice::FrameSizeFromMtu(): Unknown packet encapsulation mode");

      return 0;

    }

  return newSize;

}

  void 

CsmaNetDevice::SetEncapsulationMode (enum EncapsulationMode mode)

{

  NS_LOG_FUNCTION (mode);

  m_encapMode = mode;

  m_mtu = MtuFromFrameSize (m_frameSize);

  NS_LOG_LOGIC ("m_encapMode = " << m_encapMode);

  NS_LOG_LOGIC ("m_frameSize = " << m_frameSize);

  NS_LOG_LOGIC ("m_mtu = " << m_mtu);

}

  CsmaNetDevice::EncapsulationMode

CsmaNetDevice::GetEncapsulationMode (void)

{

  NS_LOG_FUNCTION_NOARGS ();

  return m_encapMode;

}

  bool

CsmaNetDevice::SetMtu (uint16_t mtu)

{

  NS_LOG_FUNCTION (mtu);

  uint32_t newFrameSize = FrameSizeFromMtu (mtu);

  if (newFrameSize > std::numeric_limits<uint16_t>::max ())

    {

      NS_LOG_WARN ("CsmaNetDevice::SetMtu(): Frame size overflow, MTU not set.");

      return false;

    }

  m_frameSize = newFrameSize;

  m_mtu = mtu;

  NS_LOG_LOGIC ("m_encapMode = " << m_encapMode);

  NS_LOG_LOGIC ("m_frameSize = " << m_frameSize);

  NS_LOG_LOGIC ("m_mtu = " << m_mtu);

  return true;

}

  uint16_t

CsmaNetDevice::GetMtu (void) const

{

  NS_LOG_FUNCTION_NOARGS ();

  return m_mtu;

}

  void 

CsmaNetDevice::SetFrameSize (uint16_t frameSize)

{

  NS_LOG_FUNCTION (frameSize);

  m_frameSize = frameSize;

  m_mtu = MtuFromFrameSize (frameSize);

  NS_LOG_LOGIC ("m_encapMode = " << m_encapMode);

  NS_LOG_LOGIC ("m_frameSize = " << m_frameSize);

  NS_LOG_LOGIC ("m_mtu = " << m_mtu);

}

  uint16_t

CsmaNetDevice::GetFrameSize (void) const

{

  return m_frameSize;

}

  void 

CsmaNetDevice::SetAddress (Mac48Address self)

{

  NS_LOG_FUNCTION (self);

  m_address = self;

}

  void

CsmaNetDevice::SetSendEnable (bool sendEnable)

{

  NS_LOG_FUNCTION (sendEnable);

  m_sendEnable = sendEnable;

}

  void

CsmaNetDevice::SetReceiveEnable (bool receiveEnable)

{

  NS_LOG_FUNCTION (receiveEnable);

  m_receiveEnable = receiveEnable;

}

  bool

CsmaNetDevice::IsSendEnabled (void)

{

  NS_LOG_FUNCTION_NOARGS ();

  return m_sendEnable;

}

  bool

CsmaNetDevice::IsReceiveEnabled (void)

{

  NS_LOG_FUNCTION_NOARGS ();

  return m_receiveEnable;

}

  void 

CsmaNetDevice::SetInterframeGap (Time t)

{

  NS_LOG_FUNCTION (t);

  m_tInterframeGap = t;

}

  void 

CsmaNetDevice::SetBackoffParams (Time slotTime, uint32_t minSlots, uint32_t maxSlots, uint32_t ceiling, uint32_t maxRetries)

{

  NS_LOG_FUNCTION (slotTime << minSlots << maxSlots << ceiling << maxRetries);

  m_backoff.m_slotTime = slotTime;

  m_backoff.m_minSlots = minSlots;

  m_backoff.m_maxSlots = maxSlots;

  m_backoff.m_ceiling = ceiling;

  m_backoff.m_maxRetries = maxRetries;

}

  void 

CsmaNetDevice::AddHeader (Ptr<Packet> p,   Mac48Address source,  Mac48Address dest,  uint16_t protocolNumber)

{

  NS_LOG_FUNCTION (p << source << dest << protocolNumber);

  EthernetHeader header (false);

  header.SetSource (source);

  header.SetDestination (dest);

  EthernetTrailer trailer;

  NS_LOG_LOGIC ("p->GetSize () = " << p->GetSize ());

  NS_LOG_LOGIC ("m_encapMode = " << m_encapMode);

  NS_LOG_LOGIC ("m_mtu = " << m_mtu);

  NS_LOG_LOGIC ("m_frameSize = " << m_frameSize);

  uint16_t lengthType = 0;

  switch (m_encapMode) 

    {

    case DIX:

      NS_LOG_LOGIC ("Encapsulating packet as DIX (type interpretation)");

      //

      // This corresponds to the type interpretation of the lengthType field as in the old Ethernet Blue Book.

      //

      lengthType = protocolNumber;

      break;

    case LLC: 

      {

        NS_LOG_LOGIC ("Encapsulating packet as LLC (length interpretation)");

        LlcSnapHeader llc;

        llc.SetType (protocolNumber);

        p->AddHeader (llc);

        //

        // This corresponds to the length interpretation of the lengthType field,

        // but with an LLC/SNAP header added to the payload as in IEEE 802.2

        //      

        lengthType = p->GetSize ();

        NS_ASSERT_MSG (lengthType <= m_frameSize - 18,

          "CsmaNetDevice::AddHeader(): 802.3 Length/Type field with LLC/SNAP: "

          "length interpretation must not exceed device frame size minus overhead");

      }

      break;

    case ILLEGAL:

    default:

      NS_FATAL_ERROR ("CsmaNetDevice::AddHeader(): Unknown packet encapsulation mode");

      break;

    }

  NS_LOG_LOGIC ("header.SetLengthType (" << lengthType << ")");

  header.SetLengthType (lengthType);

  p->AddHeader (header);

  trailer.CalcFcs (p);

  p->AddTrailer (trailer);

}

  bool 

CsmaNetDevice::ProcessHeader (Ptr<Packet> p, uint16_t & param)

{

  NS_LOG_FUNCTION (p << param);

  EthernetTrailer trailer;

  p->RemoveTrailer (trailer);

  trailer.CheckFcs (p);

  EthernetHeader header (false);

  p->RemoveHeader (header);

  if ((header.GetDestination () != GetBroadcast ()) &&

      (header.GetDestination () != GetAddress ()))

    {

      return false;

    }

  switch (m_encapMode)

    {

    case DIX:

      param = header.GetLengthType ();

      break;

    case LLC: 

      {

        LlcSnapHeader llc;

        p->RemoveHeader (llc);

        param = llc.GetType ();

      } 

      break;

    case ILLEGAL:

    default:

      NS_FATAL_ERROR ("CsmaNetDevice::ProcessHeader(): Unknown packet encapsulation mode");

      break;

    }

  return true;

}

  void

CsmaNetDevice::TransmitStart ()

{

  NS_LOG_FUNCTION_NOARGS ();

  NS_LOG_LOGIC ("m_currentPkt=" << m_currentPkt);

  NS_LOG_LOGIC ("UID is " << m_currentPkt->GetUid ());

  //

  // This function is called to start the process of transmitting a packet.

  // We need to tell the channel that we've started wiggling the wire and

  // schedule an event that will be executed when it's time to tell the 

  // channel that we're done wiggling the wire.

  //

  NS_ASSERT_MSG ((m_txMachineState == READY) || (m_txMachineState == BACKOFF), 

                 "Must be READY to transmit. Tx state is: " << m_txMachineState);

  //

  // Only transmit if send side of net device is enabled

  //

  if (IsSendEnabled () == false)

    {

      return;

    }

  if (m_channel->GetState () != IDLE)

    {

      //

      // The channel is busy -- backoff and rechedule TransmitStart ()

      //

      m_txMachineState = BACKOFF;

      if (m_backoff.MaxRetriesReached ())

        { 

          //

          // Too many retries, abort transmission of packet

          //

          TransmitAbort ();

        } 

      else 

        {

          m_backoff.IncrNumRetries ();

          Time backoffTime = m_backoff.GetBackoffTime ();

          NS_LOG_LOGIC ("Channel busy, backing off for " << backoffTime.GetSeconds () << " sec");

          Simulator::Schedule (backoffTime, &CsmaNetDevice::TransmitStart, this);

        }

    } 

  else 

    {

      //

      // The channel is free, transmit the packet

      //

      m_txMachineState = BUSY;

      Time tEvent = Seconds (m_bps.CalculateTxTime (m_currentPkt->GetSize ()));

      NS_LOG_LOGIC ("Schedule TransmitCompleteEvent in " << tEvent.GetSeconds () << "sec");

      Simulator::Schedule (tEvent, &CsmaNetDevice::TransmitCompleteEvent, this);

      if (m_channel->TransmitStart (m_currentPkt, m_deviceId) == false)

        {

          NS_LOG_WARN ("Channel transmit start did not work at " << tEvent.GetSeconds () << "sec");

          m_txMachineState = READY;

        } 

      else 

        {

          //

          // Transmission succeeded, reset the backoff time parameters.

          //

          m_backoff.ResetBackoffTime ();

        }

    }

}

  void