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

/*

 * Copyright (c) 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>

 */

#ifndef ARP_CACHE_H

#define ARP_CACHE_H

#include <stdint.h>

#include <list>

#include "ns3/simulator.h"

#include "ns3/callback.h"

#include "ns3/packet.h"

#include "ns3/nstime.h"

#include "ns3/net-device.h"

#include "ns3/ipv4-address.h"

#include "ns3/address.h"

#include "ns3/ptr.h"

#include "ns3/object.h"

#include "ns3/traced-callback.h"

#include "sgi-hashmap.h"

namespace ns3 {

class NetDevice;

class Ipv4Interface;

/**

 * \brief An ARP cache

 *

 * A cached lookup table for translating layer 3 addresses to layer 2.

 * This implementation does lookups from IPv4 to a MAC address

 */

class ArpCache : public Object

{

public:

  static TypeId GetTypeId (void);

  class Entry;

  ArpCache ();

  ~ArpCache ();

  /**

   * \param device The hardware NetDevice associated with this ARP chache

   * \param interface the Ipv4Interface associated with this ARP chache

   */

  void SetDevice (Ptr<NetDevice> device, Ptr<Ipv4Interface> interface);

  /**

   * \return The NetDevice that this ARP cache is associated with

   */

  Ptr<NetDevice> GetDevice (void) const;

  /**

   * \return the Ipv4Interface that this ARP cache is associated with

   */

  Ptr<Ipv4Interface> GetInterface (void) const;

  void SetAliveTimeout (Time aliveTimeout);

  void SetDeadTimeout (Time deadTimeout);

  void SetWaitReplyTimeout (Time waitReplyTimeout);

  Time GetAliveTimeout (void) const;

  Time GetDeadTimeout (void) const;

  Time GetWaitReplyTimeout (void) const;

  /**

   * This callback is set when the ArpCache is set up and allows

   * the cache to generate an Arp request when the WaitReply

   * time expires and a retransmission must be sent

   *

   * \param arpRequestCallback Callback for transmitting an Arp request.

   */

  void SetArpRequestCallback (Callback<void, Ptr<const ArpCache>, 

                             Ipv4Address> arpRequestCallback);

  /**

   * This method will schedule a timeout at WaitReplyTimeout interval

   * in the future, unless a timer is already running for the cache,

   * in which case this method does nothing.

   */

  void StartWaitReplyTimer (void);

  /**

   * \brief Do lookup in the ARP cache against an IP address

   * \param destination The destination IPv4 address to lookup the MAC address

   * of

   * \return An ArpCache::Entry with info about layer 2

   */

  ArpCache::Entry *Lookup (Ipv4Address destination);

  /**

   * \brief Add an Ipv4Address to this ARP cache

   */

  ArpCache::Entry *Add (Ipv4Address to);

  /**

   * \brief Clear the ArpCache of all entries

   */

  void Flush (void);

  /**

   * \brief A record that that holds information about an ArpCache entry

   */

  class Entry {

  public:

    /**

     * \brief Constructor

     * \param arp The ArpCache this entry belongs to

     */

    Entry (ArpCache *arp);

    /**

     * \brief Changes the state of this entry to dead

     */

    void MarkDead (void);

    /**

     * \param macAddress

     */

    void MarkAlive (Address macAddress);

    /**

     * \param waiting

     */

    void MarkWaitReply (Ptr<Packet> waiting);

    /**

     * \param waiting

     * \return 

     */

    bool UpdateWaitReply (Ptr<Packet> waiting);

    /**

     * \return True if the state of this entry is dead; false otherwise.

     */

    bool IsDead (void);

    /**

     * \return True if the state of this entry is alive; false otherwise.

     */

    bool IsAlive (void);

    /**

     * \return True if the state of this entry is wait_reply; false otherwise.

     */

    bool IsWaitReply (void);

    /**

     * \return The MacAddress of this entry

     */

    Address GetMacAddress (void) const;

    /**

     * \return The Ipv4Address for this entry

     */

    Ipv4Address GetIpv4Address (void) const;

    /**

     * \param The Ipv4Address for this entry

     */

    void SetIpv4Address (Ipv4Address destination);

    /**

     * \return True if this entry has timedout; false otherwise.

     */

    bool IsExpired (void);

    /**

     * \returns 0 is no packet is pending, the next packet to send if 

     *            packets are pending.

     */

    Ptr<Packet> DequeuePending (void);

    /**

     * \returns number of retries that have been sent for an ArpRequest

     *  in WaitReply state.

     */

    uint32_t GetRetries (void) const;

    /**

     * \brief Increment the counter of number of retries for an entry

     */

    void IncrementRetries (void);

    /**

     * \brief Zero the counter of number of retries for an entry

     */

    void ClearRetries (void);

  private:

    enum ArpCacheEntryState_e {

      ALIVE,

      WAIT_REPLY,

      DEAD

    };

    void UpdateSeen (void);

    ArpCache *m_arp;

    ArpCacheEntryState_e m_state;

    Time m_lastSeen;

    Address m_macAddress;

    Ipv4Address m_ipv4Address;

    std::list<Ptr<Packet> > m_pending;

    uint32_t m_retries;

  };

private:

  typedef sgi::hash_map<Ipv4Address, ArpCache::Entry *, Ipv4AddressHash> Cache;

  typedef sgi::hash_map<Ipv4Address, ArpCache::Entry *, Ipv4AddressHash>::iterator CacheI;

  virtual void DoDispose (void);

  Ptr<NetDevice> m_device;

  Ptr<Ipv4Interface> m_interface;

  Time m_aliveTimeout;

  Time m_deadTimeout;

  Time m_waitReplyTimeout;

  EventId m_waitReplyTimer;

  Callback<void, Ptr<const ArpCache>, Ipv4Address> m_arpRequestCallback;

  uint32_t m_maxRetries;

  /**

   * This function is an event handler for the event that the

   * ArpCache wants to check whether it must retry any Arp requests.

   * If there are no Arp requests pending, this event is not scheduled.

   */

  void HandleWaitReplyTimeout (void);

  uint32_t m_pendingQueueSize;

  Cache m_arpCache;

  TracedCallback<Ptr<const Packet> > m_dropTrace;

};

}; // namespace ns3

#endif /* ARP_CACHE_H */