/* -*- 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

 */

#ifndef CSMA_NET_DEVICE_H

#define CSMA_NET_DEVICE_H

#include <string.h>

#include "ns3/node.h"

#include "ns3/backoff.h"

#include "ns3/address.h"

#include "ns3/net-device.h"

#include "ns3/callback.h"

#include "ns3/packet.h"

#include "ns3/traced-callback.h"

#include "ns3/nstime.h"

#include "ns3/data-rate.h"

#include "ns3/ptr.h"

#include "ns3/random-variable.h"

#include "ns3/mac48-address.h"

namespace ns3 {

class Queue;

class CsmaChannel;

class ErrorModel;

/**

 * \class CsmaNetDevice

 * \brief A Device for a Csma Network Link.

 *

 * The Csma net device class is analogous to layer 1 and 2 of the

 * TCP stack. The NetDevice takes a raw packet of bytes and creates a

 * protocol specific packet from them. 

 */

class CsmaNetDevice : public NetDevice 

{

public:

  static TypeId GetTypeId (void);

  /**

   * Enumeration of the types of packets supported in the class.

   */

  enum EncapsulationMode {

    ILLEGAL,     /**< Encapsulation mode not set */

    DIX,         /**< DIX II / Ethernet II packet */

    LLC,         /**< 802.2 LLC/SNAP Packet*/  

  };

  /**

   * Construct a CsmaNetDevice

   *

   * This is the default constructor for a CsmaNetDevice.

   */

  CsmaNetDevice ();

  /**

   * Destroy a CsmaNetDevice

   *

   * This is the destructor for a CsmaNetDevice.

   */

  virtual ~CsmaNetDevice ();

  /**

   * Set the inteframe gap used to separate packets.  The interframe gap

   * defines the minimum space required between packets sent by this device.

   * As in Ethernet, it defaults to 96 bit times.

   *

   * \param t the interframe gap time

   */

  void SetInterframeGap (Time t);

  /**

   * Set the backoff parameters used to determine the wait to retry

   * transmitting a packet when the channel is busy.

   *

   * \see Attach ()

   * \param slotTime Length of a packet slot (or average packet time)

   * \param minSlots Minimum number of slots to wait

   * \param maxSlots Maximum number of slots to wait

   * \param maxRetries Maximum number of retries before packet is discard

   * \param ceiling Cap on the exponential function when calculating max slots

   */

  void SetBackoffParams (Time slotTime, uint32_t minSlots, uint32_t maxSlots, 

    uint32_t maxRetries, uint32_t ceiling);

  /**

   * Attach the device to a channel.

   *

   * The function Attach is used to add a CsmaNetDevice to a CsmaChannel.

   *

   * \see SetDataRate ()

   * \see SetInterframeGap ()

   * \param ch a pointer to the channel to which this object is being attached.

   */

  bool Attach (Ptr<CsmaChannel> ch);

  /**

   * Attach a queue to the CsmaNetDevice.

   *

   * The CsmaNetDevice "owns" a queue.  This queue may be set by higher

   * level topology objects to implement a particular queueing method such as

   * DropTail or RED.  

   *

   * \see Queue

   * \see DropTailQueue

   * \param queue a Ptr to the queue for being assigned to the device.

   */

  void SetQueue (Ptr<Queue> queue);

  /**

   * Get a copy of the attached Queue.

   *

   * \return a pointer to the queue.

   */

  Ptr<Queue> GetQueue (void) const; 

  /**

   * Attach a receive ErrorModel to the CsmaNetDevice.

   *

   * The CsmaNetDevice may optionally include an ErrorModel in

   * the packet receive chain to simulate data errors in during transmission.

   *

   * \see ErrorModel

   * \param em a pointer to the ErrorModel 

   */

  void SetReceiveErrorModel (Ptr<ErrorModel> em);

  /**

   * Receive a packet from a connected CsmaChannel.

   *

   * The CsmaNetDevice receives packets from its connected channel

   * and forwards them up the protocol stack.  This is the public method

   * used by the channel to indicate that the last bit of a packet has 

   * arrived at the device.

   *

   * \see CsmaChannel

   * \param p a reference to the received packet

   * \param sender the CsmaNetDevice that transmitted the packet in the first place

   */

  void Receive (Ptr<Packet> p, Ptr<CsmaNetDevice> sender);

  /**

   * Is the send side of the network device enabled?

   *

   * \returns True if the send side is enabled, otherwise false.

   */

  bool IsSendEnabled (void);

  /**

   * Enable or disable the send side of the network device.

   *

   * \param enable Enable the send side if true, otherwise disable.

   */

  void SetSendEnable (bool enable);

  /**

   * Is the receive side of the network device enabled?

   *

   * \returns True if the receiver side is enabled, otherwise false.

   */

  bool IsReceiveEnabled (void);

  /**

   * Enable or disable the receive side of the network device.

   *

   * \param enable Enable the receive side if true, otherwise disable.

   */

  void SetReceiveEnable (bool enable);

  /**

   * Set the encapsulation mode of this device.

   *

   * \param mode The encapsulation mode of this device.

   *

   */

  void SetEncapsulationMode (CsmaNetDevice::EncapsulationMode mode);

  /**

   * Get the encapsulation mode of this device.

   *

   * \returns The encapsulation mode of this device.

   */

  CsmaNetDevice::EncapsulationMode  GetEncapsulationMode (void);

  //

  // The following methods are inherited from NetDevice base class.

  //

  virtual void SetIfIndex (const uint32_t index);

  virtual uint32_t GetIfIndex (void) const;

  virtual Ptr<Channel> GetChannel (void) const;

  virtual bool SetMtu (const uint16_t mtu);

  virtual uint16_t GetMtu (void) const;

  virtual void SetAddress (Address address);

  virtual Address GetAddress (void) const;

  virtual bool IsLinkUp (void) const;

  virtual void AddLinkChangeCallback (Callback<void> callback);

  virtual bool IsBroadcast (void) const;

  virtual Address GetBroadcast (void) const;

  virtual bool IsMulticast (void) const;

  /**

   * \brief Make and return a MAC multicast address using the provided

   *        multicast group

   *

   * RFC 1112 says that an Ipv4 host group address is mapped to an Ethernet 

   * multicast address by placing the low-order 23-bits of the IP address into 

   * the low-order 23 bits of the Ethernet multicast address 

   * 01-00-5E-00-00-00 (hex).

   *

   * This method performs the multicast address creation function appropriate

   * to an EUI-48-based CSMA device.  This MAC address is encapsulated in an

   *  abstract Address to avoid dependencies on the exact address format.

   *

   * \param multicastGroup The IP address for the multicast group destination

   * of the packet.

   * \return The MAC multicast Address used to send packets to the provided

   * multicast group.

   *

   * \see Ipv4Address

   * \see Mac48Address

   * \see Address

   */

  virtual Address GetMulticast (Ipv4Address multicastGroup) const;

  /**

   * Is this a point to point link?

   * \returns false.

   */

  virtual bool IsPointToPoint (void) const;

  /**

   * Is this a bridge?

   * \returns false.

   */

  virtual bool IsBridge (void) const;

  /**

   * Start sending a packet down the channel.

   * \param packet packet to send

   * \param dest layer 2 destination address

   * \param protocolNumber protocol number

   * \return true if successfull, false otherwise (drop, ...)

   */

  virtual bool Send (Ptr<Packet> packet, const Address& dest, 

    uint16_t protocolNumber);

  /**

   * Start sending a packet down the channel, with MAC spoofing

   * \param packet packet to send

   * \param source layer 2 source address

   * \param dest layer 2 destination address

   * \param protocolNumber protocol number

   * \return true if successfull, false otherwise (drop, ...)

   */

  virtual bool SendFrom (Ptr<Packet> packet, const Address& source, const Address& dest, 

                         uint16_t protocolNumber);

  /**

   * Get the node to which this device is attached.

   *

   * \returns Ptr to the Node to which the device is attached.

   */

  virtual Ptr<Node> GetNode (void) const;

  /**

   * Set the node to which this device is being attached.

   *

   * \param node Ptr to the Node to which the device is being attached.

   */

  virtual void SetNode (Ptr<Node> node);

  /**

   * Does this device need to use the address resolution protocol?

   *

   * \returns True if the encapsulation mode is set to a value that requires

   * ARP (IP_ARP or LLC).

   */

  virtual bool NeedsArp (void) const;

  /**

   * Set the callback to be used to notify higher layers when a packet has been

   * received.

   *

   * \param cb The callback.

   */

  virtual void SetReceiveCallback (NetDevice::ReceiveCallback cb);

  /**

   * \brief Get the MAC multicast address corresponding

   * to the IPv6 address provided.

   * \param addr IPv6 address

   * \return the MAC multicast address

   * \warning Calling this method is invalid if IsMulticast returns not true.

   */

  virtual Address GetMulticast (Ipv6Address addr) const;

  virtual void SetPromiscReceiveCallback (PromiscReceiveCallback cb);

  virtual bool SupportsSendFrom (void) const;

protected:

  /**

   * Perform any object release functionality required to break reference 

   * cycles in reference counted objects held by the device.

   */

  virtual void DoDispose (void);

  /**

   * Adds the necessary headers and trailers to a packet of data in order to

   * respect the packet type

   *

   * \param p Packet to which header should be added

   * \param source MAC source address from which packet should be sent

   * \param dest MAC destination address to which packet should be sent

   * \param protocolNumber In some protocols, identifies the type of

   * payload contained in this packet.

   */

  void AddHeader (Ptr<Packet> p, Mac48Address source, Mac48Address dest, uint16_t protocolNumber);

private:

  /**

   * Operator = is declared but not implemented.  This disables the assigment

   * operator for CsmaNetDevice objects.

   * \param o object to copy

   */

  CsmaNetDevice &operator = (const CsmaNetDevice &o);

  /**

   * Copy constructor is declared but not implemented.  This disables the

   * copy constructor for CsmaNetDevice objects.

   * \param o object to copy

   */

  CsmaNetDevice (const CsmaNetDevice &o);

  /**

   * Initialization function used during object construction.

   * \param sendEnable if device will be allowed to send

   * \param receiveEnable if device will be allowed to receive

   */

  void Init (bool sendEnable, bool receiveEnable);

  /**

   * Start Sending a Packet Down the Wire.

   *

   * The TransmitStart method is the method that is used internally in

   * the CsmaNetDevice to begin the process of sending a packet

   * out on the channel.  A corresponding method is called on the

   * channel to let it know that the physical device this class

   * represents has actually started sending signals, this causes the

   * channel to enter the BUSY state.  An event is scheduled for the time at

   * which the bits have been completely transmitted. 

   *

   * If the channel is found to be BUSY, this method reschedules itself for

   * execution at a later time (within the backoff period).

   *

   * \see CsmaChannel::TransmitStart ()

   * \see TransmitCompleteEvent ()

   */

  void TransmitStart ();

  /**

   * Stop Sending a Packet Down the Wire and Begin the Interframe Gap.

   *

   * The TransmitCompleteEvent method is used internally to finish the process

   * of sending a packet out on the channel.  During execution of this method

   * the TransmitEnd method is called on the channel to let it know that the

   * physical device this class represents has finished sending simulated

   * signals.  The channel uses this event to begin its speed of light delay

   * timer after which it notifies the Net Device(s) at the other end of the 

   * link that new bits have arrived (it delivers the Packet).  During this 

   * method, the net device also schedules the TransmitReadyEvent at which

   * time the transmitter becomes ready to send the next packet.

   *

   * \see CsmaChannel::TransmitEnd ()

   * \see TransmitReadyEvent ()

   */

  void TransmitCompleteEvent (void);

  /**

   * Cause the Transmitter to Become Ready to Send Another Packet.

   *

   * The TransmitReadyEvent method is used internally to re-enable the 

   * transmit machine of the net device.  It is scheduled after a suitable

   * interframe gap after the completion of the previous transmission.

   * The queue is checked at this time, and if there is a packet waiting on

   * the queue, the transmission process is begun.

   *

   * If a packet is in the queue, it is extracted for the queue as the

   * next packet to be transmitted by the net device.

   *

   * \see TransmitStart ()

   */

  void TransmitReadyEvent (void);

  /**

   * Aborts the transmission of the current packet

   *

   * If the net device has tried to transmit a packet for more times

   * than the maximum allowed number of retries (channel always busy)

   * then the packet is dropped.

   */

  void TransmitAbort (void);

  /**

   * Notify any interested parties that the link has come up.

   */

  void NotifyLinkUp (void);

  /** 

   * Device ID returned by the attached functions. It is used by the

   * mp-channel to identify each net device to make sure that only

   * active net devices are writing to the channel

   */

  uint32_t m_deviceId; 

  /**

   * Enable net device to send packets. True by default

   */

  bool m_sendEnable;

  /**

   * Enable net device to receive packets. True by default

   */

  bool m_receiveEnable;

  /**

   * Enumeration of the states of the transmit machine of the net device.

   */

  enum TxMachineState

    {

      READY, /**< The transmitter is ready to begin transmission of a packet */

      BUSY,  /**< The transmitter is busy transmitting a packet */

      GAP,    /**< The transmitter is in the interframe gap time */

      BACKOFF    /**< The transmitter is waiting for the channel to be free */

    };

  /**

   * The state of the Net Device transmit state machine.

   * \see TxMachineState

   */

  TxMachineState m_txMachineState;

  /**

   * The type of packet that should be created by the AddHeader

   * function and that should be processed by the ProcessHeader

   * function.

   */

  EncapsulationMode m_encapMode;

  /**

   * The data rate that the Net Device uses to simulate packet transmission

   * timing.

   * \see class DataRate

   */

  DataRate m_bps;

  /**

   * The interframe gap that the Net Device uses insert time between packet

   * transmission

   * \see class Time

   */

  Time m_tInterframeGap;

  /**

   * Holds the backoff parameters and is used to calculate the next

   * backoff time to use when the channel is busy and the net device

   * is ready to transmit

   */

  Backoff m_backoff;

  /**

   * Next packet that will be transmitted (if transmitter is not

   * currently transmitting) or packet that is currently being

   * transmitted.

   */

  Ptr<Packet> m_currentPkt;