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

/*

 * 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

 *

 */

//

// Network topology

//

//           10Mb/s, 10ms       10Mb/s, 10ms

//       n0-----------------n1-----------------n2

//

//

// - Tracing of queues and packet receptions to file 

//   "tcp-large-transfer.tr"

// - pcap traces also generated in the following files

//   "tcp-large-transfer-$n-$i.pcap" where n and i represent node and interface

// numbers respectively

//  Usage (e.g.): ./waf --run tcp-large-transfer

#include <ctype.h>

#include <iostream>

#include <fstream>

#include <string>

#include <cassert>

#include "ns3/core-module.h"

#include "ns3/helper-module.h"

#include "ns3/applications-module.h"

#include "ns3/network-module.h"

#include "ns3/internet-module.h"

#include "ns3/ipv4-global-routing-helper.h"

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("TcpLargeTransfer");

// The number of bytes to send in this simulation.

static const uint32_t totalTxBytes = 2000000;

static uint32_t currentTxBytes = 0;

// Perform series of 1040 byte writes (this is a multiple of 26 since

// we want to detect data splicing in the output stream)

static const uint32_t writeSize = 1040;

uint8_t data[writeSize];

// These are for starting the writing process, and handling the sending 

// socket's notification upcalls (events).  These two together more or less

// implement a sending "Application", although not a proper ns3::Application

// subclass.

void StartFlow(Ptr<Socket>, Ipv4Address, uint16_t);

void WriteUntilBufferFull (Ptr<Socket>, uint32_t);

static void 

CwndTracer (uint32_t oldval, uint32_t newval)

{

  NS_LOG_INFO ("Moving cwnd from " << oldval << " to " << newval);

}

int main (int argc, char *argv[])

{

  // Users may find it convenient to turn on explicit debugging

  // for selected modules; the below lines suggest how to do this

  //  LogComponentEnable("TcpL4Protocol", LOG_LEVEL_ALL);

  //  LogComponentEnable("TcpSocketImpl", LOG_LEVEL_ALL);

  //  LogComponentEnable("PacketSink", LOG_LEVEL_ALL);

  //  LogComponentEnable("TcpLargeTransfer", LOG_LEVEL_ALL);

  CommandLine cmd;

  cmd.Parse (argc, argv);

  // initialize the tx buffer.

  for(uint32_t i = 0; i < writeSize; ++i)

    {

      char m = toascii (97 + i % 26);

      data[i] = m;

    }

  // Here, we will explicitly create three nodes.  The first container contains

  // nodes 0 and 1 from the diagram above, and the second one contains nodes

  // 1 and 2.  This reflects the channel connectivity, and will be used to

  // install the network interfaces and connect them with a channel.

  NodeContainer n0n1;

  n0n1.Create (2);

  NodeContainer n1n2;

  n1n2.Add (n0n1.Get (1));

  n1n2.Create (1);

  // We create the channels first without any IP addressing information

  // First make and configure the helper, so that it will put the appropriate

  // attributes on the network interfaces and channels we are about to install.

  PointToPointHelper p2p;

  p2p.SetDeviceAttribute ("DataRate", DataRateValue (DataRate(10000000)));

  p2p.SetChannelAttribute ("Delay", TimeValue (MilliSeconds(10)));

  // And then install devices and channels connecting our topology.

  NetDeviceContainer dev0 = p2p.Install (n0n1);

  NetDeviceContainer dev1 = p2p.Install (n1n2);

  // Now add ip/tcp stack to all nodes.

  InternetStackHelper internet;

  internet.InstallAll ();

  // Later, we add IP addresses.

  Ipv4AddressHelper ipv4;

  ipv4.SetBase ("10.1.3.0", "255.255.255.0");

  ipv4.Assign (dev0);

  ipv4.SetBase ("10.1.2.0", "255.255.255.0");

  Ipv4InterfaceContainer ipInterfs = ipv4.Assign (dev1);

  // and setup ip routing tables to get total ip-level connectivity.

  Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

  ///////////////////////////////////////////////////////////////////////////

  // Simulation 1

  //

  // Send 2000000 bytes over a connection to server port 50000 at time 0

  // Should observe SYN exchange, a lot of data segments and ACKS, and FIN 

  // exchange.  FIN exchange isn't quite compliant with TCP spec (see release

  // notes for more info)

  //

  ///////////////////////////////////////////////////////////////////////////

  uint16_t servPort = 50000;

  // Create a packet sink to receive these packets on n2...

  PacketSinkHelper sink ("ns3::TcpSocketFactory",

                         InetSocketAddress (Ipv4Address::GetAny (), servPort));

  ApplicationContainer apps = sink.Install (n1n2.Get (1));

  apps.Start (Seconds (0.0));

  apps.Stop (Seconds (3.0));

  // Create a source to send packets from n0.  Instead of a full Application

  // and the helper APIs you might see in other example files, this example

  // will use sockets directly and register some socket callbacks as a sending

  // "Application".

  // Create and bind the socket...

  Ptr<Socket> localSocket =

      Socket::CreateSocket (n0n1.Get (0), TcpSocketFactory::GetTypeId ());

  localSocket->Bind ();

  // Trace changes to the congestion window

  Config::ConnectWithoutContext ("/NodeList/0/$ns3::TcpL4Protocol/SocketList/0/CongestionWindow", MakeCallback (&CwndTracer));

  // ...and schedule the sending "Application"; This is similar to what an 

  // ns3::Application subclass would do internally.

  Simulator::ScheduleNow (&StartFlow, localSocket,

                          ipInterfs.GetAddress (1), servPort);

  // One can toggle the comment for the following line on or off to see the

  // effects of finite send buffer modelling.  One can also change the size of

  // said buffer.

  //localSocket->SetAttribute("SndBufSize", UintegerValue(4096));

  //Ask for ASCII and pcap traces of network traffic

  AsciiTraceHelper ascii;

  p2p.EnableAsciiAll (ascii.CreateFileStream ("tcp-large-transfer.tr"));

  p2p.EnablePcapAll ("tcp-large-transfer");

  // Finally, set up the simulator to run.  The 1000 second hard limit is a

  // failsafe in case some change above causes the simulation to never end

  Simulator::Stop (Seconds(1000));

  Simulator::Run ();

  Simulator::Destroy ();

}

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------

//begin implementation of sending "Application"

void StartFlow(Ptr<Socket> localSocket,

               Ipv4Address servAddress,

               uint16_t servPort)

{

  NS_LOG_LOGIC("Starting flow at time " <<  Simulator::Now ().GetSeconds ());

  localSocket->Connect (InetSocketAddress (servAddress, servPort));//connect

  // tell the tcp implementation to call WriteUntilBufferFull again

  // if we blocked and new tx buffer space becomes available

  localSocket->SetSendCallback (MakeCallback (&WriteUntilBufferFull));

  WriteUntilBufferFull (localSocket, localSocket->GetTxAvailable ());

}

void WriteUntilBufferFull (Ptr<Socket> localSocket, uint32_t txSpace)

{

  while (currentTxBytes < totalTxBytes && localSocket->GetTxAvailable () > 0) 

    {

      uint32_t left = totalTxBytes - currentTxBytes;

      uint32_t dataOffset = currentTxBytes % writeSize;

      uint32_t toWrite = writeSize - dataOffset;

      toWrite = std::min (toWrite, left);

      toWrite = std::min (toWrite, localSocket->GetTxAvailable ());

      int amountSent = localSocket->Send (&data[dataOffset], toWrite, 0);

      if(amountSent < 0)

        {

          // we will be called again when new tx space becomes available.

          return;

        }

      currentTxBytes += amountSent;

    }

  localSocket->Close ();

}