/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2007 Georgia Tech Research Corporation
 *
 * 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: Raj Bhattacharjea <raj.b@gatech.edu>
 */


#include "ns3/node.h"
#include "ns3/inet-socket-address.h"
#include "ns3/log.h"
#include "ns3/ipv4.h"
#include "tcp-socket.h"
#include "tcp-l4-protocol.h"
#include "ipv4-end-point.h"
#include "ipv4-l4-demux.h"
#include "ns3/simulation-singleton.h"
#include "tcp-typedefs.h"
#include "ns3/simulator.h"
#include "ns3/packet.h"

#include <algorithm>

NS_LOG_COMPONENT_DEFINE ("TcpSocket");

using namespace std;

namespace ns3 {

  TcpSocket::TcpSocket (Ptr<Node> node, Ptr<TcpL4Protocol> tcp, Ptr<RttEstimator> rtt)
  : m_skipRetxResched (false),
    m_dupAckCount (0),
    m_endPoint (0),
    m_node (node),
    m_tcp (tcp),
    m_errno (ERROR_NOTERROR),
    m_shutdownSend (false),
    m_shutdownRecv (false),
    m_connected (false),
    m_state (CLOSED),
    m_closeNotified (false),
    m_closeRequestNotified (false),
    m_closeOnEmpty (false),
    m_pendingClose (false),
    m_nextTxSequence (0),
    m_highTxMark (0),
    m_highestRxAck (0),
    m_lastRxAck (0),
    m_nextRxSequence (0),
    m_pendingData (0),
    m_rtt (rtt),
    m_lastMeasuredRtt (Seconds(0.0))
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this<<node<<tcp);
  
  Ptr<Tcp> t = node->GetObject<Tcp> ();
  m_segmentSize = t->GetDefaultSegSize ();
  m_rxWindowSize = t->GetDefaultAdvWin ();
  m_advertisedWindowSize = t->GetDefaultAdvWin ();
  m_cWnd = t->GetDefaultInitialCwnd () * m_segmentSize;
  m_ssThresh = t->GetDefaultSsThresh ();
  m_initialCWnd = t->GetDefaultInitialCwnd ();
  m_cnTimeout = Seconds (t->GetDefaultConnTimeout ());
  m_cnCount = t->GetDefaultConnCount ();

}

TcpSocket::~TcpSocket ()
{
  NS_LOG_FUNCTION;
  m_node = 0;
  if (m_endPoint != 0)
    {
      NS_ASSERT (m_tcp != 0);
      /**
       * Note that this piece of code is a bit tricky:
       * when DeAllocate is called, it will call into
       * Ipv4EndPointDemux::Deallocate which triggers
       * a delete of the associated endPoint which triggers
       * in turn a call to the method ::Destroy below
       * will will zero the m_endPoint field.
       */
      NS_ASSERT (m_endPoint != 0);
      m_tcp->DeAllocate (m_endPoint);
      NS_ASSERT (m_endPoint == 0);
    }
  m_tcp = 0;
  delete m_pendingData; //prevents leak
  m_pendingData = 0;
}

enum Socket::SocketErrno
TcpSocket::GetErrno (void) const
{
  NS_LOG_FUNCTION;
  return m_errno;
}

Ptr<Node>
TcpSocket::GetNode (void) const
{
  NS_LOG_FUNCTION;
  return m_node;
}

void 
TcpSocket::Destroy (void)
{
  NS_LOG_FUNCTION;
  m_node = 0;
  m_endPoint = 0;
  m_tcp = 0;
  m_retxEvent.Cancel ();
}
int
TcpSocket::FinishBind (void)
{
  NS_LOG_FUNCTION;
  if (m_endPoint == 0)
    {
      return -1;
    }
  m_endPoint->SetRxCallback (MakeCallback (&TcpSocket::ForwardUp, this));
  m_endPoint->SetDestroyCallback (MakeCallback (&TcpSocket::Destroy, this));
  return 0;
}

int
TcpSocket::Bind (void)
{
  NS_LOG_FUNCTION;
  m_endPoint = m_tcp->Allocate ();
  return FinishBind ();
}
int 
TcpSocket::Bind (const Address &address)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this<<address);
  if (!InetSocketAddress::IsMatchingType (address))
    {
      return ERROR_INVAL;
    }
  InetSocketAddress transport = InetSocketAddress::ConvertFrom (address);
  Ipv4Address ipv4 = transport.GetIpv4 ();
  uint16_t port = transport.GetPort ();
  Ipv4Address localInterface = Ipv4Address::GetAny ();
  if (ipv4 != Ipv4Address::GetAny ())
    {
      Ptr<Ipv4> ipv4_api = m_node->GetObject<Ipv4> ();
      // Assert that the given address matches an existing local interface
      NS_ASSERT (ipv4_api->FindInterfaceForAddr (ipv4) != 0);
      localInterface = ipv4;
    }
  if (ipv4 == Ipv4Address::GetAny () && port == 0)
    {
      m_endPoint = m_tcp->Allocate ();
      NS_LOG_LOGIC ("TcpSocket "<<this<<" got an endpoint: "<<m_endPoint);
    }
  else if (ipv4 == Ipv4Address::GetAny () && port != 0)
    {
      m_endPoint = m_tcp->Allocate (port);
      NS_LOG_LOGIC ("TcpSocket "<<this<<" got an endpoint: "<<m_endPoint);
    }
  else if (ipv4 != Ipv4Address::GetAny () && port == 0)
    {
      m_endPoint = m_tcp->Allocate (ipv4, localInterface);
      NS_LOG_LOGIC ("TcpSocket "<<this<<" got an endpoint: "<<m_endPoint);
    }
  else if (ipv4 != Ipv4Address::GetAny () && port != 0)
    {
      m_endPoint = m_tcp->Allocate (ipv4, port, localInterface);
      NS_LOG_LOGIC ("TcpSocket "<<this<<" got an endpoint: "<<m_endPoint);
    }

  return FinishBind ();
}

int 
TcpSocket::ShutdownSend (void)
{
  NS_LOG_FUNCTION;
  m_shutdownSend = true;
  return 0;
}
int 
TcpSocket::ShutdownRecv (void)
{
  NS_LOG_FUNCTION;
  m_shutdownRecv = false;
  return 0;
}

int
TcpSocket::Close (void)
{
  NS_LOG_FUNCTION;
  if (m_state == CLOSED) 
    {
      return -1;
    }
  Actions_t action  = ProcessEvent (APP_CLOSE);
  if (m_pendingData)
    {
      if (action == FIN_TX && m_pendingData->Size () != 0 )
        {
          m_closeOnEmpty = true;
          return 0;
        }
    }
  ProcessAction (action);
  ShutdownSend ();
  return 0;
}

int
TcpSocket::Connect (const Address & address)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << address);
  if (m_endPoint == 0)
    {
      if (Bind () == -1)
        {
          NS_ASSERT (m_endPoint == 0);
          return -1;
        }
      NS_ASSERT (m_endPoint != 0);
    }
  InetSocketAddress transport = InetSocketAddress::ConvertFrom (address);
  m_defaultAddress = transport.GetIpv4 ();
  m_defaultPort = transport.GetPort ();
  
  uint32_t localIfIndex;
  Ptr<Ipv4> ipv4 = m_node->GetObject<Ipv4> ();

  if (ipv4->GetIfIndexForDestination (m_defaultAddress, localIfIndex))
    {
      m_endPoint->SetLocalAddress (ipv4->GetAddress (localIfIndex));
    }
  else
    {
      m_errno = ERROR_NOROUTETOHOST;
      return -1;
    }

  Actions_t action = ProcessEvent (APP_CONNECT);
  bool success = ProcessAction (action);
  if (success) 
    {
      return 0;
    }
  return -1;
}
int 
TcpSocket::Send (const Ptr<Packet> p) //p here is just data, no headers
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << p);
  if (m_state == ESTABLISHED || m_state == SYN_SENT || m_state == CLOSE_WAIT)
    { // Ok to buffer some data to send
      if (!m_pendingData)
        {
          m_pendingData = new PendingData (0);   // Create if non-existent
          m_firstPendingSequence = m_nextTxSequence; // Note seq of first
        }
      //PendingData::Add always copies the data buffer, never modifies
      m_pendingData->Add (p->GetSize (), p->PeekData ());
      Actions_t action = ProcessEvent (APP_SEND);
      if (!ProcessAction (action)) 
        {
          return -1; // Failed, return zero
        }
      return p->GetSize ();
    }
  else
    {
      m_errno = ERROR_NOTCONN;
      return -1;
    }
}

int TcpSocket::Send (const uint8_t* buf, uint32_t size)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << buf << size);
  if (m_state == ESTABLISHED || m_state == SYN_SENT || m_state == CLOSE_WAIT)
    { // Ok to buffer some data to send
      if (!m_pendingData)
      {
        m_pendingData = new PendingData ();   // Create if non-existent
        m_firstPendingSequence = m_nextTxSequence; // Note seq of first
      }
      //PendingData::Add always copies the data buffer, never modifies
      m_pendingData->Add (size,buf);
      Actions_t action = ProcessEvent (APP_SEND);
      if (!ProcessAction (action)) 
        {
          return -1; // Failed, return zero
        }
      return size;
    }
  else
  {
    m_errno = ERROR_NOTCONN;
    return -1;
  }
}

int TcpSocket::DoSendTo (Ptr<Packet> p, const Address &address)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << p << address);
  InetSocketAddress transport = InetSocketAddress::ConvertFrom (address);
  Ipv4Address ipv4 = transport.GetIpv4 ();
  uint16_t port = transport.GetPort ();
  return DoSendTo (p, ipv4, port);
}

int TcpSocket::DoSendTo (Ptr<Packet> p, Ipv4Address ipv4, uint16_t port)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << p << ipv4 << port);
  if (m_endPoint == 0)
    {
      if (Bind () == -1)
	{
          NS_ASSERT (m_endPoint == 0);
	  return -1;
	}
      NS_ASSERT (m_endPoint != 0);
    }
  if (m_shutdownSend)
    {
      m_errno = ERROR_SHUTDOWN;
      return -1;
    }
  m_tcp->Send (p, m_endPoint->GetLocalAddress (), ipv4,
                  m_endPoint->GetLocalPort (), port);
  NotifyDataSent (p->GetSize ());
  return 0;
}

int 
TcpSocket::SendTo (const Address &address, Ptr<Packet> p)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << address << p);
  if (!m_connected)
    {
      m_errno = ERROR_NOTCONN;
      return -1;
    }
  else
    {
      return Send (p); //drop the address according to BSD manpages
    }
}

int
TcpSocket::Listen (uint32_t q)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << q);
  Actions_t action = ProcessEvent (APP_LISTEN);
  ProcessAction (action);
  return 0;
}

void
TcpSocket::ForwardUp (Ptr<Packet> packet, Ipv4Address ipv4, uint16_t port)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << packet << ipv4 << port);
  if (m_shutdownRecv)
    {
      return;
    }
  TcpHeader tcpHeader;
  packet->RemoveHeader (tcpHeader);

  if (tcpHeader.GetFlags () & TcpHeader::ACK)
    {
      Time m = m_rtt->AckSeq (tcpHeader.GetAckNumber () );
      if (m != Seconds (0.0))
        {
          m_lastMeasuredRtt = m;
        }
    }

  Events_t event = SimulationSingleton<TcpStateMachine>::Get ()->FlagsEvent (tcpHeader.GetFlags () );
  Actions_t action = ProcessEvent (event); //updates the state
  Address address = InetSocketAddress (ipv4, port);
  ProcessPacketAction (action, packet, tcpHeader, address);
}

Actions_t TcpSocket::ProcessEvent (Events_t e)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << e);
  States_t saveState = m_state;
  NS_LOG_LOGIC ("TcpSocket " << this << " processing event " << e);
  // simulation singleton is a way to get a single global static instance of a
  // class intended to be a singleton; see simulation-singleton.h
  SA stateAction = SimulationSingleton<TcpStateMachine>::Get ()->Lookup (m_state,e);
  // debug
  if (stateAction.action == RST_TX)
    {
      NS_LOG_LOGIC ("TcpSocket " << this << " sending RST from state "
              << saveState << " event " << e);
    }
  bool needCloseNotify = (stateAction.state == CLOSED && m_state != CLOSED 
    && e != TIMEOUT);
  m_state = stateAction.state;
  NS_LOG_LOGIC ("TcpSocket " << this << " moved from state " << saveState 
    << " to state " <<m_state);
  NS_LOG_LOGIC ("TcpSocket " << this << " pendingData " << m_pendingData);
  if (saveState == SYN_SENT && m_state == ESTABLISHED)
    // this means the application side has completed its portion of 
    // the handshaking
    {
      NotifyConnectionSucceeded ();
      m_connected = true;
      m_endPoint->SetPeer (m_defaultAddress, m_defaultPort);
      NS_LOG_LOGIC ("TcpSocket " << this << " Connected!");
    }
  if (needCloseNotify && !m_closeNotified)
    {
      NS_LOG_LOGIC ("TcpSocket " << this << " transition to CLOSED from " 
               << m_state << " event " << e << " closeNot " << m_closeNotified
               << " action " << stateAction.action);
      NotifyCloseCompleted ();
      m_closeNotified = true;
      NS_LOG_LOGIC ("TcpSocket " << this << " calling Closed from PE"
              << " origState " << saveState
              << " event " << e);
      NS_LOG_LOGIC ("TcpSocket " << this << " transition to CLOSED from "
          << m_state << " event " << e
          << " set CloseNotif ");
    }
  return stateAction.action;
}

void TcpSocket::SendEmptyPacket (uint8_t flags)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << flags);
  Ptr<Packet> p = Create<Packet> ();
  TcpHeader header;

  header.SetFlags (flags);
  header.SetSequenceNumber (m_nextTxSequence);
  header.SetAckNumber (m_nextRxSequence);
  header.SetSourcePort (m_endPoint->GetLocalPort ());
  header.SetDestinationPort (m_defaultPort);
  header.SetWindowSize (m_advertisedWindowSize);
  m_tcp->SendPacket (p, header, m_endPoint->GetLocalAddress (), 
    m_defaultAddress);
  Time rto = m_rtt->RetransmitTimeout ();
  if (flags & TcpHeader::SYN)
    {
      rto = m_cnTimeout;
      m_cnTimeout = m_cnTimeout + m_cnTimeout;
      m_cnCount--;
    }
  if (m_retxEvent.IsExpired () ) //no outstanding timer
  {
    NS_LOG_LOGIC ("Schedule retransmission timeout at time " 
          << Simulator::Now ().GetSeconds () << " to expire at time " 
          << (Simulator::Now () + rto).GetSeconds ());
    m_retxEvent = Simulator::Schedule (rto, &TcpSocket::ReTxTimeout, this);
  }
}

bool TcpSocket::ProcessAction (Actions_t a)
{ // These actions do not require a packet or any TCP Headers
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << a);
  switch (a)
  {
    case NO_ACT:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action: NO_ACT");
      break;
    case ACK_TX:
      SendEmptyPacket (TcpHeader::ACK);
      break;
    case ACK_TX_1:
      NS_ASSERT (false); // This should be processed in ProcessPacketAction
      break;
    case RST_TX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action RST_TX");
      SendEmptyPacket (TcpHeader::RST);
      break;
    case SYN_TX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action SYN_TX");
      // TCP SYN Flag consumes one byte
      // is the above correct? we're SENDING a syn, not acking back -- Raj
      // commented out for now
      // m_nextTxSequence+= 1;
      SendEmptyPacket (TcpHeader::SYN);
      break;
    case SYN_ACK_TX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action SYN_ACK_TX");
      SendEmptyPacket (TcpHeader::SYN | TcpHeader::ACK);
      break;
    case FIN_TX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action FIN_TX");
      SendEmptyPacket (TcpHeader::FIN);
      break;
    case FIN_ACK_TX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action FIN_ACK_TX");
      SendEmptyPacket (TcpHeader::FIN | TcpHeader::ACK);
      break;
    case NEW_ACK:
      NS_ASSERT (false); // This should be processed in ProcessPacketAction
      break;
    case NEW_SEQ_RX:
      NS_ASSERT (false); // This should be processed in ProcessPacketAction
      break;
    case RETX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action RETX");
      break;
    case TX_DATA:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action TX_DATA");
      SendPendingData ();
      break;
    case PEER_CLOSE:
      NS_ASSERT (false); // This should be processed in ProcessPacketAction
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action PEER_CLOSE");
      break;
    case APP_CLOSED:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action APP_CLOSED");
      break;
    case CANCEL_TM:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action CANCEL_TM");
      break;
    case APP_NOTIFY:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action APP_NOTIFY");
      break;
    case SERV_NOTIFY:
      NS_ASSERT (false); // This should be processed in ProcessPacketAction
      break;
    case LAST_ACTION:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action LAST_ACTION");
      break;
  }
  return true;
}

bool TcpSocket::ProcessPacketAction (Actions_t a, Ptr<Packet> p,
                                     const TcpHeader& tcpHeader,
                                     const Address& fromAddress)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << p << "tcpHeader " << fromAddress);
  uint32_t localIfIndex;
  Ptr<Ipv4> ipv4 = m_node->GetObject<Ipv4> ();
  switch (a)
  {
    case SYN_ACK_TX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action SYN_ACK_TX");
      m_defaultPort = InetSocketAddress::ConvertFrom (fromAddress).GetPort ();
      m_defaultAddress = 
        InetSocketAddress::ConvertFrom (fromAddress).GetIpv4 ();
      m_endPoint->SetPeer (m_defaultAddress, m_defaultPort);
      if (ipv4->GetIfIndexForDestination (m_defaultAddress, localIfIndex))
        {
          m_endPoint->SetLocalAddress (ipv4->GetAddress (localIfIndex));
        }
      // TCP SYN consumes one byte
      m_nextRxSequence = tcpHeader.GetSequenceNumber() + SequenceNumber(1);
      SendEmptyPacket (TcpHeader::SYN | TcpHeader::ACK);
      break;
    case ACK_TX_1:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action ACK_TX_1");
      // TCP SYN consumes one byte
      m_nextRxSequence = tcpHeader.GetSequenceNumber() + SequenceNumber(1);
      SendEmptyPacket (TcpHeader::ACK);
      m_rxWindowSize = tcpHeader.GetWindowSize ();
      m_nextTxSequence = tcpHeader.GetAckNumber ();
      if (tcpHeader.GetAckNumber () > m_highestRxAck)
      {
        m_highestRxAck = tcpHeader.GetAckNumber ();
      }
      SendPendingData ();
      break;
    case NEW_ACK:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action NEW_ACK_TX");
      if (tcpHeader.GetAckNumber () < m_highestRxAck) //old ack, do nothing
      {
        break;
      }
      if (tcpHeader.GetAckNumber () == m_highestRxAck && 
         tcpHeader.GetAckNumber ()  < m_nextTxSequence)
      {
        DupAck (tcpHeader, ++m_dupAckCount);
        break;
      }
      if (tcpHeader.GetAckNumber () > m_highestRxAck)  
        {
          m_dupAckCount = 0;
        }
      NewAck (tcpHeader.GetAckNumber ());
      break;
    case NEW_SEQ_RX:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action NEW_SEQ_TX");
      NewRx (p, tcpHeader, fromAddress); // Process new data received
      break;
    case PEER_CLOSE:
    {
      // First we have to be sure the FIN packet was not received
      // out of sequence.  If so, note pending close and process
      // new sequence rx
      if (tcpHeader.GetSequenceNumber () != m_nextRxSequence)
        { // process close later
          m_pendingClose = true;
          NS_LOG_LOGIC ("TcpSocket " << this << " setting pendingClose" 
            << " rxseq " << tcpHeader.GetSequenceNumber () 
            << " nextRxSeq " << m_nextRxSequence);
          NewRx (p, tcpHeader, fromAddress);
          return true;
        }
      // Now we need to see if any data came with the FIN
      // if so, call NewRx
      if (p->GetSize () != 0)
        {
          NewRx (p, tcpHeader, fromAddress);
        }
      States_t saveState = m_state; // Used to see if app responds
      NS_LOG_LOGIC ("TcpSocket " << this 
          << " peer close, state " << m_state);
      if (!m_closeRequestNotified)
        {
          NS_LOG_LOGIC ("TCP " << this 
              << " calling AppCloseRequest");
          NotifyCloseRequested ();
          m_closeRequestNotified = true;
        }
      NS_LOG_LOGIC ("TcpSocket " << this 
          << " peer close, state after " << m_state);
      if (m_state == saveState)
        { // Need to ack, the application will close later
          SendEmptyPacket (TcpHeader::ACK);
              // Also need to re-tx the ack if we
        }
      if (m_state == LAST_ACK)
        {
          NS_LOG_LOGIC ("TcpSocket " << this << " scheduling LATO1");
          m_lastAckEvent = Simulator::Schedule (m_rtt->RetransmitTimeout (),
                                                &TcpSocket::LastAckTimeout,this);
        }
      break;
    }
    case SERV_NOTIFY:
      NS_LOG_LOGIC ("TcpSocket " << this <<" Action SERV_NOTIFY");
      NS_LOG_LOGIC ("TcpSocket " << this << " Connected!");
      NotifyNewConnectionCreated (this, fromAddress);
      m_connected = true; // ! This is bogus; fix when we clone the tcp
      m_endPoint->SetPeer (m_defaultAddress, m_defaultPort);
      //treat the connection orientation final ack as a newack
      CommonNewAck (tcpHeader.GetAckNumber (), true);
      break;
    default:
      break;
  }
  return true;
}

bool TcpSocket::SendPendingData (bool withAck)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << withAck);
  NS_LOG_LOGIC ("ENTERING SendPendingData");
  if (!m_pendingData)
    {
      return false; // No data exists
    }
  uint32_t nPacketsSent = 0;
  while (m_pendingData->SizeFromSeq (m_firstPendingSequence, m_nextTxSequence))
    {
      uint32_t w = AvailableWindow ();// Get available window size
      NS_LOG_LOGIC ("TcpSocket " << this << " SendPendingData"
           << " w " << w 
           << " rxwin " << m_rxWindowSize
           << " cWnd " << m_cWnd
           << " segsize " << m_segmentSize
           << " nextTxSeq " << m_nextTxSequence
           << " highestRxAck " << m_highestRxAck 
           << " pd->Size " << m_pendingData->Size ()
           << " pd->SFS " << m_pendingData->SizeFromSeq (m_firstPendingSequence, m_nextTxSequence));

      if (w < m_segmentSize && m_pendingData->Size () > w)
        {
          break; // No more
        }
      uint32_t s = std::min (w, m_segmentSize);  // Send no more than window
      Ptr<Packet> p = m_pendingData->CopyFromSeq (s, m_firstPendingSequence, 
        m_nextTxSequence);
      NS_LOG_LOGIC("TcpSocket " << this << " sendPendingData"
                   << " txseq " << m_nextTxSequence
                   << " s " << s 
                   << " datasize " << p->GetSize() );
      uint8_t flags = 0;
      if (withAck)
        {
          flags |= TcpHeader::ACK;
        }
      uint32_t sz = p->GetSize (); // Size of packet
      uint32_t remainingData = m_pendingData->SizeFromSeq(
          m_firstPendingSequence,
          m_nextTxSequence + SequenceNumber (sz));
      if (m_closeOnEmpty && (remainingData == 0))
        {
          flags = TcpHeader::FIN;
          m_state = FIN_WAIT_1;
        }

      TcpHeader header;
      header.SetFlags (flags);
      header.SetSequenceNumber (m_nextTxSequence);
      header.SetAckNumber (m_nextRxSequence);
      header.SetSourcePort (m_endPoint->GetLocalPort());
      header.SetDestinationPort (m_defaultPort);
      if (m_shutdownSend)
        {
          m_errno = ERROR_SHUTDOWN;
          return -1;
        }

      Time rto = m_rtt->RetransmitTimeout ();
      if (m_retxEvent.IsExpired () ) //go ahead and schedule the retransmit
        {
          NS_LOG_LOGIC ("Schedule retransmission timeout at time " << 
              Simulator::Now ().GetSeconds () << " to expire at time " <<
              (Simulator::Now () + rto).GetSeconds () );
          m_retxEvent = Simulator::Schedule (rto,&TcpSocket::ReTxTimeout,this);
        }
      NS_LOG_LOGIC ("About to send a packet with flags: " << flags);
      m_tcp->SendPacket (p, header,
                         m_endPoint->GetLocalAddress (),
                         m_defaultAddress);
      m_rtt->SentSeq(m_nextTxSequence, sz);       // notify the RTT
      // Notify the application
      Simulator::ScheduleNow(&TcpSocket::NotifyDataSent, this, p->GetSize ());
      nPacketsSent++;                             // Count sent this loop
      m_nextTxSequence += sz;                     // Advance next tx sequence
      // Note the high water mark
      m_highTxMark = std::max (m_nextTxSequence, m_highTxMark);
    }
  NS_LOG_LOGIC ("Sent "<<nPacketsSent<<" packets");
  NS_LOG_LOGIC("RETURN SendPendingData");
  return (nPacketsSent>0);
}

uint32_t  TcpSocket::UnAckDataCount ()
{
  NS_LOG_FUNCTION;
  return m_nextTxSequence - m_highestRxAck;
}

uint32_t  TcpSocket::BytesInFlight ()
{
  NS_LOG_FUNCTION;
  return m_highTxMark - m_highestRxAck;
}

uint32_t  TcpSocket::Window ()
{
  NS_LOG_FUNCTION;
  NS_LOG_LOGIC ("TcpSocket::Window() "<<this);
  return std::min (m_rxWindowSize, m_cWnd);
}

uint32_t  TcpSocket::AvailableWindow ()
{
  NS_LOG_FUNCTION;
  uint32_t unack = UnAckDataCount (); // Number of outstanding bytes
  uint32_t win = Window ();
  if (win < unack) 
    {
      return 0;  // No space available
    }
  return (win - unack);       // Amount of window space available
}

void TcpSocket::NewRx (Ptr<Packet> p,
                        const TcpHeader& tcpHeader, 
                        const Address& fromAddress)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << p << "tcpHeader " << fromAddress);
  NS_LOG_LOGIC ("TcpSocket " << this << " NewRx, p.size is " << p->GetSize () );
  States_t origState = m_state;
  uint32_t s = p->GetSize ();  // Size of associated data
  if (s == 0)
    {// Nothing to do if no associated data
      return;
    }
  // Log sequence received if enabled
  // NoteTimeSeq(LOG_SEQ_RX, h->sequenceNumber);
  // Three possibilities
  // 1) Received seq is expected, deliver this and any buffered data
  // 2) Received seq is < expected, just re-ack previous
  // 3) Received seq is > expected, just re-ack previous and buffer data
  if (tcpHeader.GetSequenceNumber () == m_nextRxSequence)
    { // If seq is expected seq
      // 1) Update nextRxSeq
      // 2) Deliver to application this packet
      // 3) See if any buffered can be delivered
      // 4) Send the ack
      m_nextRxSequence += s;           // Advance next expected sequence
      //bytesReceived += s;       // Statistics
      NS_LOG_LOGIC("Case 1, advanced nrxs to " << m_nextRxSequence );
	  NotifyDataReceived (p, fromAddress);
      if (m_closeNotified)
        {
          NS_LOG_LOGIC ("Tcp " << this << " HuH?  Got data after closeNotif");
        }
      NS_LOG_LOGIC ("TcpSocket " << this << " adv rxseq by " << s);
      // Look for buffered data
      UnAckData_t::iterator i;
      // Note that the bufferedData list DOES contain the tcp header
      while (!m_bufferedData.empty ())
        { // Check the buffered data for delivery
          NS_LOG_LOGIC("TCP " << this << " bufferedData.size() " 
              << m_bufferedData.size () 
              << " time " << Simulator::Now ());
          i = m_bufferedData.begin ();
          Ptr<Packet> p1 = i->second;
          SequenceNumber s1 = 0;
          if (i->first > m_nextRxSequence) 
            {
              break;  // Not next expected
            }
          // already have the header as a param
          //TCPHeader* h = dynamic_cast<TCPHeader*>(p1->PopPDU());
          // Check non-null here...
          uint8_t flags = tcpHeader.GetFlags ();           // Flags (used below)
          if (i->first < m_nextRxSequence)
            { // remove already delivered data
              // Two cases here.
              // 1) seq + length <= nextRxSeq, just discard
              // 2) seq + length > nextRxSeq, can deliver partial
              s1 = p->GetSize ();
              if (i->first + s1 < m_nextRxSequence)
                { // Just remove from list
                  //bufferedData.erase(i);
                  p1 = 0; // Nothing to deliver
                }
              else
                { // Remove partial data to prepare for delivery
                  uint32_t dup = m_nextRxSequence - i->first;
                  i->second = p1->CreateFragment (0, p1->GetSize () - dup);
                  p1 = i->second;
                }
            }
          else
            { // At this point i->first must equal nextRxSeq
              if (i->first != m_nextRxSequence)
                {
                  NS_FATAL_ERROR ("HuH?  NexRx failure, first " 
                      << i->first << " nextRxSeq " << m_nextRxSequence);
                }
              s1 = p1->GetSize ();
            }
          NotifyDataReceived (p1, fromAddress);

          NS_LOG_LOGIC ("TcpSocket " << this << " adv rxseq1 by " << s1 );
          m_nextRxSequence += s1;           // Note data received
          m_bufferedData.erase (i);     // Remove from list
          if (flags & TcpHeader::FIN)
            NS_LOG_LOGIC("TcpSocket " << this 
                    << " found FIN in buffered");
        }

      if (m_pendingClose || (origState > ESTABLISHED))
        { // See if we can close now
          if (m_bufferedData.empty())
            {
              ProcessPacketAction (PEER_CLOSE, p, tcpHeader, fromAddress);
            }
        }
    }
  else if (SequenceNumber (tcpHeader.GetSequenceNumber ()) >= m_nextRxSequence)
    { // Need to buffer this one
      NS_LOG_LOGIC ("Case 2, buffering " << tcpHeader.GetSequenceNumber () );
      UnAckData_t::iterator i = 
        m_bufferedData.find (tcpHeader.GetSequenceNumber () );
      if (i != m_bufferedData.end () )
        {
          i->second = 0; // relase reference to already buffered
        }
      // Save for later delivery
      m_bufferedData[tcpHeader.GetSequenceNumber () ] = p;  
    }
  else
    { // debug
      NS_LOG_LOGIC("TCP " << this 
               << " got seq " << tcpHeader.GetSequenceNumber ()
               << " expected " << m_nextRxSequence
               << "       flags " << tcpHeader.GetFlags ());
    }
  // Now send a new ack packet acknowledging all received and delivered data
  SendEmptyPacket (TcpHeader::ACK);
}


void TcpSocket::CommonNewAck (SequenceNumber ack, bool skipTimer)
{ // CommonNewAck is called only for "New" (non-duplicate) acks
  // and MUST be called by any subclass, from the NewAck function
  // Always cancel any pending re-tx timer on new acknowledgement
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << ack << skipTimer);
  //DEBUG(1,(cout << "TCP " << this << "Cancelling retx timer " << endl));
  if (!skipTimer)
    {
      m_retxEvent.Cancel ();
    }
  NS_LOG_LOGIC ("TCP " << this << " NewAck " << ack 
           << " numberAck " << (ack - m_highestRxAck)); // Number bytes ack'ed
  m_highestRxAck = ack;         // Note the highest recieved Ack
  if (ack > m_nextTxSequence) 
    {
      m_nextTxSequence = ack; // If advanced
    }
  // See if all pending ack'ed; if so we can delete the data
  if (m_pendingData)
    { // Data exists, see if can be deleted
      if (m_pendingData->SizeFromSeq (m_firstPendingSequence, m_highestRxAck) == 0)
        { // All pending acked, can be deleted
          m_pendingData->Clear ();
          delete m_pendingData;
          m_pendingData = 0;
          // Insure no re-tx timer
          m_retxEvent.Cancel ();
        }
    }
  // Try to send more data
  SendPendingData();
}

void TcpSocket::NewAck (SequenceNumber seq)
{ // New acknowledgement up to sequence number "seq"
  // Adjust congestion window in response to new ack's received
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << seq);
  NS_LOG_LOGIC ("TcpSocket " << this << " NewAck "
           << " seq " << seq
           << " cWnd " << m_cWnd
           << " ssThresh " << m_ssThresh);
  if (m_cWnd < m_ssThresh)
    { // Slow start mode, add one segSize to cWnd
      m_cWnd += m_segmentSize;
      NS_LOG_LOGIC ("TcpSocket " << this << " NewCWnd SlowStart, cWnd " << m_cWnd 
          << " sst " << m_ssThresh);
    }
  else
    { // Congestion avoidance mode, adjust by (ackBytes*segSize) / cWnd
      double adder =  ((double) m_segmentSize * m_segmentSize) / m_cWnd;
      if (adder < 1.0) 
        {
          adder = 1.0;
        }
      m_cWnd += (uint32_t) adder;
      NS_LOG_LOGIC ("NewCWnd CongAvoid, cWnd " << m_cWnd 
           << " sst " << m_ssThresh);
    }
  CommonNewAck (seq, false);           // Complete newAck processing
}

void TcpSocket::DupAck (const TcpHeader& t, uint32_t count)
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this << "t " << count);
  NS_LOG_LOGIC ("TcpSocket " << this << " DupAck " <<  t.GetAckNumber ()
      << ", count " << count
      << ", time " << Simulator::Now ());
  if (count == 3)
  { // Count of three indicates triple duplicate ack
    m_ssThresh = Window () / 2; // Per RFC2581
    m_ssThresh = std::max (m_ssThresh, 2 * m_segmentSize);
    NS_LOG_LOGIC("TcpSocket " << this << "Tahoe TDA, time " << Simulator::Now ()
        << " seq " << t.GetAckNumber ()
        << " in flight " << BytesInFlight ()
        << " new ssthresh " << m_ssThresh);

    m_cWnd = m_segmentSize; // Collapse cwnd (re-enter slowstart)
    // For Tahoe, we also reset nextTxSeq
    m_nextTxSequence = m_highestRxAck;
    SendPendingData ();
  }
}

void TcpSocket::ReTxTimeout ()
{ // Retransmit timeout
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this);
  m_ssThresh = Window () / 2; // Per RFC2581
  m_ssThresh = std::max (m_ssThresh, 2 * m_segmentSize);
  // Set cWnd to segSize on timeout,  per rfc2581
  // Collapse congestion window (re-enter slowstart)
  m_cWnd = m_segmentSize;           
  m_nextTxSequence = m_highestRxAck; // Start from highest Ack
  m_rtt->IncreaseMultiplier (); // Double timeout value for next retx timer
  Retransmit ();             // Retransmit the packet
}

void TcpSocket::LastAckTimeout ()
{
  m_lastAckEvent.Cancel ();
  if (m_state == LAST_ACK)
    {
      Actions_t action = ProcessEvent (TIMEOUT);
      ProcessAction (action);
    }
  if (!m_closeNotified)
    {
      m_closeNotified = true;
    }
}

void TcpSocket::Retransmit ()
{
  NS_LOG_FUNCTION;
  NS_LOG_PARAMS (this);
  uint8_t flags = TcpHeader::NONE;
  if (m_state == SYN_SENT) 
    {
      if (m_cnCount > 0) 
        {
          SendEmptyPacket (TcpHeader::SYN);
          return;
        }
      else
        {
          NotifyConnectionFailed ();
          return;
        }
    } 
  if (!m_pendingData)
    {
      if (m_state == FIN_WAIT_1 || m_state == FIN_WAIT_2)
        { // Must have lost FIN, re-send
          SendEmptyPacket (TcpHeader::FIN);
        }
      return;
    }
  Ptr<Packet> p = m_pendingData->CopyFromSeq (m_segmentSize,
                                            m_firstPendingSequence,
                                            m_highestRxAck);
  // Calculate remaining data for COE check
  uint32_t remainingData = m_pendingData->SizeFromSeq (
      m_firstPendingSequence,
      m_nextTxSequence + SequenceNumber(p->GetSize ()));
  if (m_closeOnEmpty && remainingData == 0)
    { // Add the FIN flag
      flags = flags | TcpHeader::FIN;
    }

  NS_LOG_LOGIC ("TcpSocket " << this << " retxing seq " << m_highestRxAck);
  if (m_retxEvent.IsExpired () )
    {
      Time rto = m_rtt->RetransmitTimeout ();
      NS_LOG_LOGIC ("Schedule retransmission timeout at time "
          << Simulator::Now ().GetSeconds () << " to expire at time "
          << (Simulator::Now () + rto).GetSeconds ());
      m_retxEvent = Simulator::Schedule (rto,&TcpSocket::ReTxTimeout,this);
    }
  m_rtt->SentSeq (m_highestRxAck,p->GetSize ());
  // And send the packet
  TcpHeader tcpHeader;
  tcpHeader.SetSequenceNumber (m_nextTxSequence);
  tcpHeader.SetAckNumber (m_nextRxSequence);
  tcpHeader.SetSourcePort (m_endPoint->GetLocalPort());
  tcpHeader.SetDestinationPort (m_defaultPort);
  tcpHeader.SetFlags (flags);
  tcpHeader.SetWindowSize (m_advertisedWindowSize);

  m_tcp->SendPacket (p, tcpHeader, m_endPoint->GetLocalAddress (),
    m_defaultAddress);
}

}//namespace ns3