/*

 * Copyright (c) 2005 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/assert.h"

#include "ns3/abort.h"

#include "ns3/log.h"

#include "ns3/header.h"

#include "ipv4-header.h"

NS_LOG_COMPONENT_DEFINE ("Ipv4Header");

namespace ns3 {

NS_OBJECT_ENSURE_REGISTERED (Ipv4Header);

Ipv4Header::Ipv4Header ()

  : m_calcChecksum (false),

    m_payloadSize (0),

    m_identification (0),

    m_tos (0),

    m_ttl (0),

    m_protocol (0),

    m_flags (0),

    m_fragmentOffset (0),

    m_checksum (0),

    m_goodChecksum (true)

{

}

void

Ipv4Header::EnableChecksum (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 offsetBytes)

{

  // check if the user is trying to set an invalid offset

  NS_ABORT_MSG_IF ((offsetBytes & 0x7), "offsetBytes must be multiple of 8 bytes");

  m_fragmentOffset = offsetBytes;

}

uint16_t 

Ipv4Header::GetFragmentOffset (void) const

{

  if ((m_fragmentOffset+m_payloadSize+5*4) > 65535)

    {

      NS_LOG_WARN("Fragment will exceed the maximum packet size once reassembled");

    }

  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;

}

TypeId 

Ipv4Header::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::Ipv4Header")

    .SetParent<Header> ()

    .AddConstructor<Ipv4Header> ()

  ;

  return tid;

}

TypeId 

Ipv4Header::GetInstanceTypeId (void) const

{

  return GetTypeId ();

}

void 

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

{

  // ipv4, right ?

  std::string flags;

  if (m_flags == 0)

    {

      flags = "none";

    }

  else if (m_flags & MORE_FRAGMENTS &&

           m_flags & DONT_FRAGMENT)

    {

      flags = "MF|DF";

    }

  else if (m_flags & DONT_FRAGMENT)

    {

      flags = "DF";

    }

  else if (m_flags & MORE_FRAGMENTS)

    {

      flags = "MF";

    }

  else

    {

      flags = "XX";

    }

  os << "tos 0x" << std::hex << m_tos << std::dec << " "

     << "ttl " << m_ttl << " "

     << "id " << m_identification << " "

     << "protocol " << m_protocol << " "

     << "offset (bytes) " << m_fragmentOffset << " "

     << "flags [" << flags << "] "

     << "length: " << (m_payloadSize + 5 * 4)

     << " " 

     << m_source << " > " << m_destination

  ;

}

uint32_t 

Ipv4Header::GetSerializedSize (void) const

{

  return 5 * 4;

}

void

Ipv4Header::Serialize (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.Get ());

  i.WriteHtonU32 (m_destination.Get ());

  if (m_calcChecksum) 

    {

      i = start;

      uint16_t checksum = i.CalculateIpChecksum (20);

      NS_LOG_LOGIC ("checksum=" <<checksum);

      i = start;

      i.Next (10);

      i.WriteU16 (checksum);

    }

}

uint32_t

Ipv4Header::Deserialize (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;

    }

  i.Prev ();

  m_fragmentOffset = i.ReadU8 () & 0x1f;

  m_fragmentOffset <<= 8;

  m_fragmentOffset |= i.ReadU8 ();

  m_fragmentOffset <<= 3;

  m_ttl = i.ReadU8 ();

  m_protocol = i.ReadU8 ();

  m_checksum = i.ReadU16 ();

  /* i.Next (2); // checksum */

  m_source.Set (i.ReadNtohU32 ());

  m_destination.Set (i.ReadNtohU32 ());

  if (m_calcChecksum) 

    {

      i = start;

      uint16_t checksum = i.CalculateIpChecksum (headerSize);

      NS_LOG_LOGIC ("checksum=" <<checksum);

      m_goodChecksum = (checksum == 0);

    }

  return GetSerializedSize ();

}

}; // namespace ns3