/* -*-  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>

 */

#include "ns3/packet.h"

#include "ns3/log.h"

#include "ns3/node.h"

#include "ns3/net-device.h"

#include "ns3/object-vector.h"

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

#include "ns3/ipv4-route.h"

#include "ipv4-l3-protocol.h"

#include "arp-l3-protocol.h"

#include "arp-header.h"

#include "arp-cache.h"

#include "ipv4-interface.h"

NS_LOG_COMPONENT_DEFINE ("ArpL3Protocol");

namespace ns3 {

const uint16_t ArpL3Protocol::PROT_NUMBER = 0x0806;

NS_OBJECT_ENSURE_REGISTERED (ArpL3Protocol);

TypeId 

ArpL3Protocol::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::ArpL3Protocol")

    .SetParent<Object> ()

    .AddConstructor<ArpL3Protocol> ()

    .AddAttribute ("CacheList",

                   "The list of ARP caches",

                   ObjectVectorValue (),

                   MakeObjectVectorAccessor (&ArpL3Protocol::m_cacheList),

                   MakeObjectVectorChecker<ArpCache> ())

    .AddTraceSource ("Drop",

                     "Packet dropped because not enough room in pending queue for a specific cache entry.",

                     MakeTraceSourceAccessor (&ArpL3Protocol::m_dropTrace))

    ;

  return tid;

}

ArpL3Protocol::ArpL3Protocol ()

{

  NS_LOG_FUNCTION (this);

}

ArpL3Protocol::~ArpL3Protocol ()

{

  NS_LOG_FUNCTION (this);

}

void 

ArpL3Protocol::SetNode (Ptr<Node> node)

{

  NS_LOG_FUNCTION (this);

  m_node = node;

}

/*

 * This method is called by AddAgregate and completes the aggregation

 * by setting the node in the ipv4 stack

 */

void

ArpL3Protocol::NotifyNewAggregate ()

{

  if (m_node == 0)

    {

      Ptr<Node>node = this->GetObject<Node> ();

      //verify that it's a valid node and that

      //the node was not set before

      if (node != 0)

        {

          this->SetNode (node);

        }

    }

  Object::NotifyNewAggregate ();

}

void 

ArpL3Protocol::DoDispose (void)

{

  NS_LOG_FUNCTION (this);

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

    {

      Ptr<ArpCache> cache = *i;

      cache->Dispose ();

    }

  m_cacheList.clear ();

  m_node = 0;

  Object::DoDispose ();

}

Ptr<ArpCache> 

ArpL3Protocol::CreateCache (Ptr<NetDevice> device, Ptr<Ipv4Interface> interface)

{

  NS_LOG_FUNCTION (this << device << interface);

  Ptr<Ipv4L3Protocol> ipv4 = m_node->GetObject<Ipv4L3Protocol> ();

  Ptr<ArpCache> cache = CreateObject<ArpCache> ();

  cache->SetDevice (device, interface);

  NS_ASSERT (device->IsBroadcast ());

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

  cache->SetArpRequestCallback (MakeCallback (&ArpL3Protocol::SendArpRequest, this));

  m_cacheList.push_back (cache);

  return cache;

}

Ptr<ArpCache>

ArpL3Protocol::FindCache (Ptr<NetDevice> device)

{

  NS_LOG_FUNCTION (this << device);

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

    {

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

	{

	  return *i;

	}

    }

  NS_ASSERT (false);

  // quiet compiler

  return 0;

}

void 

ArpL3Protocol::Receive(Ptr<NetDevice> device, Ptr<const Packet> p, uint16_t protocol, const Address &from,

                       const Address &to, NetDevice::PacketType packetType)

{

  NS_LOG_FUNCTION (this << device << p->GetSize () << protocol << from << to << packetType);

  Ptr<Packet> packet = p->Copy ();

  NS_LOG_LOGIC ("ARP: received packet of size "<< packet->GetSize ());

  Ptr<ArpCache> cache = FindCache (device);

  // 

  // If we're connected to a real world network, then some of the fields sizes 

  // in an ARP packet can vary in ways not seen in simulations.  We need to be

  // able to detect ARP packets with headers we don't recongnize and not process

  // them instead of crashing.  The ArpHeader will return 0 if it can't deal

  // with the received header.

  //

  ArpHeader arp;

  uint32_t size = packet->RemoveHeader (arp);

  if (size == 0)

    {

      NS_LOG_LOGIC ("ARP: Cannot remove ARP header");

      return;

    }

  NS_LOG_LOGIC ("ARP: received "<< (arp.IsRequest ()? "request" : "reply") <<

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

            arp.GetSourceIpv4Address () << " for address " <<

            arp.GetDestinationIpv4Address () << "; we have addresses: ");

  for (uint32_t i = 0; i < cache->GetInterface ()->GetNAddresses (); i++)

    {

      NS_LOG_LOGIC (cache->GetInterface ()->GetAddress (i).GetLocal () << ", ");

    }

  /**

   * Note: we do not update the ARP cache when we receive an ARP request

   * from an unknown node. See bug #107

   */

  bool found = false;

  for (uint32_t i = 0; i < cache->GetInterface ()->GetNAddresses (); i++)

    {

      if (arp.IsRequest () && arp.GetDestinationIpv4Address () == 

        cache->GetInterface ()->GetAddress (i).GetLocal ()) 

        {

          found = true;

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

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

          SendArpReply (cache, arp.GetDestinationIpv4Address (), arp.GetSourceIpv4Address (),

                    arp.GetSourceHardwareAddress ());

          break;

        } 

      else if (arp.IsReply () && 

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

        arp.GetDestinationHardwareAddress () == device->GetAddress ()) 

        {

          found = true;

          Ipv4Address from = arp.GetSourceIpv4Address ();

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

          if (entry != 0)

            {

              if (entry->IsWaitReply ()) 

                {

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

                    ", got reply from " << arp.GetSourceIpv4Address ()

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

                  Address from_mac = arp.GetSourceHardwareAddress ();

                  entry->MarkAlive (from_mac);

                  Ptr<Packet> pending = entry->DequeuePending();

                  while (pending != 0)

                    {

                      cache->GetInterface ()->Send (pending,

                                                arp.GetSourceIpv4Address ());

                      pending = entry->DequeuePending();

                    }

                } 

              else 

                {

                  // ignore this reply which might well be an attempt 

                  // at poisening my arp cache.

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

                        arp.GetSourceIpv4Address () << 

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

                  m_dropTrace (packet);

                }

            } 

          else 

            {

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

              m_dropTrace (packet);

            }

          break;

        }

    }

  if (found == false)

    {

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

                arp.GetSourceIpv4Address () << " for unknown address " <<

                arp.GetDestinationIpv4Address () << " -- drop");

    }

}

bool 

ArpL3Protocol::Lookup (Ptr<Packet> packet, Ipv4Address destination, 

                       Ptr<NetDevice> device,

                       Ptr<ArpCache> cache,

                       Address *hardwareDestination)

{

  NS_LOG_FUNCTION (this << packet << destination << device << cache);

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

  if (entry != 0)

    {

      if (entry->IsExpired ()) 

        {

          if (entry->IsDead ()) 

            {

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

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

              entry->MarkWaitReply (packet);

              SendArpRequest (cache, destination);

            } 

          else if (entry->IsAlive ()) 

            {

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

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

              entry->MarkWaitReply (packet);

              SendArpRequest (cache, destination);

            } 

          else if (entry->IsWaitReply ()) 

            {

              NS_FATAL_ERROR ("Test for possibly unreachable code-- please file a bug report, with a test case, if this is ever hit");

            }

        } 

      else 

        {

          if (entry->IsDead ()) 

            {

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

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

              m_dropTrace (packet);

            } 

          else if (entry->IsAlive ()) 

            {

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

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

	      *hardwareDestination = entry->GetMacAddress ();

              return true;

            } 

          else if (entry->IsWaitReply ()) 

            {

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

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

              if (!entry->UpdateWaitReply (packet))

                {

                  m_dropTrace (packet);

                }

            }

        }

    }

  else

    {

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

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

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

      entry = cache->Add (destination);

      entry->MarkWaitReply (packet);

      SendArpRequest (cache, destination);

    }

  return false;

}

void

ArpL3Protocol::SendArpRequest (Ptr<const ArpCache> cache, Ipv4Address to)

{

  NS_LOG_FUNCTION (this << cache << to);

  ArpHeader arp;

  // need to pick a source address; use routing implementation to select

  Ptr<Ipv4L3Protocol> ipv4 = m_node->GetObject<Ipv4L3Protocol> ();

  int32_t interface = ipv4->GetInterfaceForDevice (cache->GetDevice ());

  NS_ASSERT (interface >= 0);

  Ipv4Header header;

  header.SetDestination (to);

  Socket::SocketErrno errno_;

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

  Ptr<Ipv4Route> route = ipv4->GetRoutingProtocol ()->RouteOutput (packet, header, interface, errno_);

  NS_ASSERT (route != 0);

  NS_LOG_LOGIC ("ARP: sending request from node "<<m_node->GetId ()<<

            " || src: " << cache->GetDevice ()->GetAddress () <<

            " / " << route->GetSource () <<

            " || dst: " << cache->GetDevice ()->GetBroadcast () <<

            " / " << to);

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

		  route->GetSource (),

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

                  to);

  packet->AddHeader (arp);

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

}

void

ArpL3Protocol::SendArpReply (Ptr<const ArpCache> cache, Ipv4Address myIp, Ipv4Address toIp, Address toMac)

{

  NS_LOG_FUNCTION (this << cache << toIp << toMac);

  ArpHeader arp;

  NS_LOG_LOGIC ("ARP: sending reply from node "<<m_node->GetId ()<<

            "|| src: " << cache->GetDevice ()->GetAddress () << 

            " / " << myIp <<

            " || dst: " << toMac << " / " << toIp);

  arp.SetReply (cache->GetDevice ()->GetAddress (), myIp, toMac, toIp);

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

  packet->AddHeader (arp);

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

}

}//namespace ns3