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

/*

 * Copyright (c) 2005 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/assert.h"

#include "ns3/debug.h"

#include "ns3/header.h"

#include "ipv4-header.h"

NS_DEBUG_COMPONENT_DEFINE ("Ipv4Header");

namespace ns3 {

static uint16_t 

UtilsNtoh16 (uint16_t v)

{

  uint16_t val;

  uint8_t *array;

  array = (uint8_t *)&v;

  val = (array[0] << 8) | (array[1] << 0);

  return val;

}

bool Ipv4Header::m_calcChecksum = false;

Ipv4Header::Ipv4Header ()

  : m_payloadSize (0),

    m_identification (0),

    m_tos (0),

    m_ttl (0),

    m_protocol (0),

    m_flags (0),

    m_fragmentOffset (0),

    m_goodChecksum (true)

{}

Ipv4Header::~Ipv4Header ()

{}

void 

Ipv4Header::EnableChecksums (void)

{

  m_calcChecksum = true;

}

void 

Ipv4Header::SetPayloadSize (uint16_t size)

{

  m_payloadSize = size;

}

uint16_t 

Ipv4Header::GetPayloadSize (void) const

{

  return m_payloadSize;

}

uint16_t 

Ipv4Header::GetIdentification (void) const

{

  return m_identification;

}

void 

Ipv4Header::SetIdentification (uint16_t identification)

{

  m_identification = identification;

}

void 

Ipv4Header::SetTos (uint8_t tos)

{

  m_tos = tos;

}

uint8_t 

Ipv4Header::GetTos (void) const

{

  return m_tos;

}

void 

Ipv4Header::SetMoreFragments (void)

{

  m_flags |= MORE_FRAGMENTS;

}

void

Ipv4Header::SetLastFragment (void)

{

  m_flags &= ~MORE_FRAGMENTS;

}

bool 

Ipv4Header::IsLastFragment (void) const

{

  return !(m_flags & MORE_FRAGMENTS);

}

void 

Ipv4Header::SetDontFragment (void)

{

  m_flags |= DONT_FRAGMENT;

}

void 

Ipv4Header::SetMayFragment (void)

{

  m_flags &= ~DONT_FRAGMENT;

}

bool 

Ipv4Header::IsDontFragment (void) const

{

  return (m_flags & DONT_FRAGMENT);

}

void 

Ipv4Header::SetFragmentOffset (uint16_t offset)

{

  NS_ASSERT (!(offset & (~0x3fff)));

  m_fragmentOffset = offset;

}

uint16_t 

Ipv4Header::GetFragmentOffset (void) const

{

  NS_ASSERT (!(m_fragmentOffset & (~0x3fff)));

  return m_fragmentOffset;

}

void 

Ipv4Header::SetTtl (uint8_t ttl)

{

  m_ttl = ttl;

}

uint8_t 

Ipv4Header::GetTtl (void) const

{

  return m_ttl;

}

uint8_t 

Ipv4Header::GetProtocol (void) const

{

  return m_protocol;

}

void 

Ipv4Header::SetProtocol (uint8_t protocol)

{

  m_protocol = protocol;

}

void 

Ipv4Header::SetSource (Ipv4Address source)

{

  m_source = source;

}

Ipv4Address

Ipv4Header::GetSource (void) const

{

  return m_source;

}

void 

Ipv4Header::SetDestination (Ipv4Address dst)

{

  m_destination = dst;

}

Ipv4Address

Ipv4Header::GetDestination (void) const

{

  return m_destination;

}

bool

Ipv4Header::IsChecksumOk (void) const

{

  return m_goodChecksum;

}

void 

Ipv4Header::PrintTo (std::ostream &os) const

{

  // ipv4, right ?

  os << "(ipv4)"

     << " tos=" << (uint32_t)m_tos

     << ", payload length=" << UtilsNtoh16 (m_payloadSize)

     << ", id=" << m_identification

     << ", " << (IsLastFragment ()?"last":"more")

     << ", " << (IsDontFragment ()?"dont":"may")

     << ", frag offset=" << m_fragmentOffset

     << ", ttl=" << m_ttl

     << ", protocol=" << m_protocol

     << ", source=" << m_source

     << ", destination=" << m_destination;

}

uint32_t 

Ipv4Header::GetSerializedSize (void) const

{

  return 5 * 4;

}

void

Ipv4Header::SerializeTo (Buffer::Iterator start) const

{

  Buffer::Iterator i = start;

  uint8_t verIhl = (4 << 4) | (5);

  i.WriteU8 (verIhl);

  i.WriteU8 (m_tos);

  i.WriteHtonU16 (m_payloadSize + 5*4);

  i.WriteHtonU16 (m_identification);

  uint32_t fragmentOffset = m_fragmentOffset / 8;

  uint8_t flagsFrag = (fragmentOffset >> 8) & 0x1f;

  if (m_flags & DONT_FRAGMENT) 

    {

      flagsFrag |= (1<<6);

    }

  if (m_flags & MORE_FRAGMENTS) 

    {

      flagsFrag |= (1<<5);

    }

  i.WriteU8 (flagsFrag);

  uint8_t frag = fragmentOffset & 0xff;

  i.WriteU8 (frag);

  i.WriteU8 (m_ttl);

  i.WriteU8 (m_protocol);

  i.WriteHtonU16 (0);

  i.WriteHtonU32 (m_source.GetHostOrder ());

  i.WriteHtonU32 (m_destination.GetHostOrder ());

  if (m_calcChecksum) 

    {

#if 0

      // XXX we need to add Buffer::Iterator::PeekData method

      uint8_t *data = start.PeekData ();

      uint16_t checksum = UtilsChecksumCalculate (0, data, GetSize ());

      checksum = UtilsChecksumComplete (checksum);

      NS_DEBUG ("checksum=" <<checksum);

      i = start;

      i.Next (10);

      i.WriteU16 (checksum);

#endif

    }

}

uint32_t

Ipv4Header::DeserializeFrom (Buffer::Iterator start)

{

  Buffer::Iterator i = start;

  uint8_t verIhl = i.ReadU8 ();

  uint8_t ihl = verIhl & 0x0f; 

  uint16_t headerSize = ihl * 4;

  NS_ASSERT ((verIhl >> 4) == 4);

  m_tos = i.ReadU8 ();

  uint16_t size = i.ReadNtohU16 ();

  m_payloadSize = size - headerSize;

  m_identification = i.ReadNtohU16 ();

  uint8_t flags = i.ReadU8 ();

  m_flags = 0;

  if (flags & (1<<6)) 

    {

      m_flags |= DONT_FRAGMENT;

    }

  if (flags & (1<<5)) 

    {

      m_flags |= MORE_FRAGMENTS;

    }

  //XXXX I think we should clear some bits in fragmentOffset !

  i.Prev ();

  m_fragmentOffset = i.ReadNtohU16 ();

  m_fragmentOffset *= 8;

  m_ttl = i.ReadU8 ();

  m_protocol = i.ReadU8 ();

  i.Next (2); // checksum

  m_source.SetHostOrder (i.ReadNtohU32 ());

  m_destination.SetHostOrder (i.ReadNtohU32 ());

  if (m_calcChecksum) 

    {

#if 0

      uint8_t *data = start.PeekData ();

      uint16_t localChecksum = UtilsChecksumCalculate (0, data, headerSize);

      if (localChecksum == 0xffff) 

        {

          m_goodChecksum = true;

        } 

      else 

        {

          m_goodChecksum = false;

        }

#endif

    }

  return GetSerializedSize ();

}

}; // namespace ns3