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

/*

 * Copyright (c) 2006 INRIA

 * All rights reserved.

 *

 * 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/debug.h"

#include "ns3/empty-trace-resolver.h"

#include "arp.h"

#include "arp-header.h"

#include "arp-cache.h"

#include "net-device.h"

#include "ipv4-interface.h"

#include "node.h"

#include "ipv4.h"

NS_DEBUG_COMPONENT_DEFINE ("Arp");

namespace ns3 {

const uint16_t Arp::PROT_NUMBER = 0x0806;

Arp::Arp (Node *node)

  : L3Protocol (PROT_NUMBER, 0/* XXX: correct version number ? */ ),

    m_node (node)

{}

Arp::~Arp ()

{

  for (CacheList::const_iterator i = m_cacheList.begin (); i != m_cacheList.end (); i++)

    {

      delete *i;

    }

}

Arp *

Arp::Copy (Node *node) const

{

  return new Arp (node);

}

TraceResolver *

Arp::CreateTraceResolver (TraceContext const &context)

{

  return new EmptyTraceResolver (context);

}

ArpCache *

Arp::FindCache (NetDevice *device)

{

  for (CacheList::const_iterator i = m_cacheList.begin (); i != m_cacheList.end (); i++)

    {

      if ((*i)->GetDevice () == device)

	{

	  return *i;

	}

    }

  Ipv4Interface *interface = m_node->GetIpv4 ()->FindInterfaceForDevice (device);

  ArpCache * cache = new ArpCache (device, interface);

  NS_ASSERT (device->IsBroadcast ());

  device->SetLinkChangeCallback (MakeCallback (&ArpCache::Flush, cache));

  m_cacheList.push_back (cache);

  return cache;

}

void 

Arp::Receive(Packet& packet, NetDevice &device)

{

  ArpCache *cache = FindCache (&device);

  ArpHeader arp;

  packet.Peek (arp);

  packet.Remove (arp);

  if (arp.IsRequest () && 

      arp.GetDestinationIpv4Address () == cache->GetInterface ()->GetAddress ()) 

    {

      NS_DEBUG ("node="<<m_node->GetId () <<", got request from " << 

                arp.GetSourceIpv4Address () << " -- send reply");

      SendArpReply (cache, arp.GetSourceIpv4Address (),

                    arp.GetSourceHardwareAddress ());

    } 

  else if (arp.IsReply () &&

           arp.GetDestinationIpv4Address ().IsEqual (cache->GetInterface ()->GetAddress ()) &&

           arp.GetDestinationHardwareAddress ().IsEqual (device.GetAddress ())) 

    {

      Ipv4Address from = arp.GetSourceIpv4Address ();

      ArpCache::Entry *entry = cache->Lookup (from);

      if (entry != 0)

        {

          if (entry->IsWaitReply ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<", got reply from " << 

                        arp.GetSourceIpv4Address ()

                     << " for waiting entry -- flush");

              MacAddress from_mac = arp.GetSourceHardwareAddress ();

              Packet waiting = entry->MarkAlive (from_mac);

	      cache->GetInterface ()->Send (waiting, arp.GetSourceIpv4Address ());

            } 

          else 

            {

              // ignore this reply which might well be an attempt 

              // at poisening my arp cache.

              NS_DEBUG ("node="<<m_node->GetId ()<<", got reply from " << 

                        arp.GetSourceIpv4Address () << 

                        " for non-waiting entry -- drop");

	      // XXX report packet as dropped.

            }

        } 

      else 

        {

          NS_DEBUG ("node="<<m_node->GetId ()<<", got reply for unknown entry -- drop");

	  // XXX report packet as dropped.

        }

    }

}

bool 

Arp::Lookup (Packet &packet, Ipv4Address destination, 

	     NetDevice *device,

	     MacAddress *hardwareDestination)

{

  ArpCache *cache = FindCache (device);

  ArpCache::Entry *entry = cache->Lookup (destination);

  if (entry != 0)

    {

      if (entry->IsExpired ()) 

        {

          if (entry->IsDead ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<

                        ", dead entry for " << destination << " expired -- send arp request");

              entry->MarkWaitReply (packet);

              SendArpRequest (cache, destination);

            } 

          else if (entry->IsAlive ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<

                        ", alive entry for " << destination << " expired -- send arp request");

              entry->MarkWaitReply (packet);

              SendArpRequest (cache, destination);

            } 

          else if (entry->IsWaitReply ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<

                        ", wait reply for " << destination << " expired -- drop");

              entry->MarkDead ();

	      // XXX report packet as 'dropped'

            }

        } 

      else 

        {

          if (entry->IsDead ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<

                        ", dead entry for " << destination << " valid -- drop");

	      // XXX report packet as 'dropped'

            } 

          else if (entry->IsAlive ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<

                        ", alive entry for " << destination << " valid -- send");

	      *hardwareDestination = entry->GetMacAddress ();

              return true;

            } 

          else if (entry->IsWaitReply ()) 

            {

              NS_DEBUG ("node="<<m_node->GetId ()<<

                        ", wait reply for " << destination << " valid -- drop previous");

              Packet old = entry->UpdateWaitReply (packet);

	      // XXX report 'old' packet as 'dropped'

            }

        }

    }

  else

    {

      // This is our first attempt to transmit data to this destination.

      NS_DEBUG ("node="<<m_node->GetId ()<<

                ", no entry for " << destination << " -- send arp request");

      entry = cache->Add (destination);

      entry->MarkWaitReply (packet);

      SendArpRequest (cache, destination);

    }

  return false;

}

void

Arp::SendArpRequest (ArpCache const *cache, Ipv4Address to)

{

  ArpHeader arp;

  arp.SetRequest (cache->GetDevice ()->GetAddress (),

		  cache->GetInterface ()->GetAddress (), 

                  cache->GetDevice ()->GetBroadcast (),

                  to);

  Packet packet;

  packet.Add (arp);

  cache->GetDevice ()->Send (packet, cache->GetDevice ()->GetBroadcast (), PROT_NUMBER);

}

void

Arp::SendArpReply (ArpCache const *cache, Ipv4Address toIp, MacAddress toMac)

{

  ArpHeader arp;

  arp.SetReply (cache->GetDevice ()->GetAddress (),

                cache->GetInterface ()->GetAddress (),

                toMac, toIp);

  Packet packet;

  packet.Add (arp);

  cache->GetDevice ()->Send (packet, toMac, PROT_NUMBER);

}

}//namespace ns3