/* -*- 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
 *
 * Contributed by:  Luis Cortes (cortes@gatech.edu)
 */


// This script exercises global routing code in a mixed point-to-point
// and csma/cd environment
//
// Network topology
//
//  n0
//     \ p-p
//      \          (shared csma/cd)
//       n2 -------------------------n3
//      /            |        | 
//     / p-p        n4        n5 ---------- n6
//   n1                             p-p
//   |                                      |
//   ----------------------------------------
//                p-p
//
// - at time 1 CBR/UDP flow from n1 to n6's IP address on the n5/n6 link
// - at time 10, start similar flow from n1 to n6's address on the n1/n6 link
//
//  Order of events
//  At pre-simulation time, configure global routes.  Shortest path from
//  n1 to n6 is via the direct point-to-point link
//  At time 1s, start CBR traffic flow from n1 to n6
//  At time 2s, set the n1 point-to-point interface to down.  Packets
//    will start to be dropped 
//  At time 3s, call RecomputeRoutingTables() and traffic will
//    start flowing again on the alternate path
//  At time 4s, re-enable the n1/n6 interface to up.  Will not change routing
//  At time 5s, call RecomputeRoutingTables() and traffic will start flowing 
//    again on the original path
//  At time 6s, set the n6-n1 point-to-point Ipv4 interface to down (note, this
//    keeps the point-to-point link "up" from n1's perspective).  Packets
//    will traverse the link and be dropped at n6 upon receipt.  These drops
//    are not visible in the pcap trace but in the ascii trace.
//  At time 7s, call RecomputeRoutingTables() and traffic will flow again
//    through the path n1-n2-n5-n6
//  At time 8s, bring the interface back up.
//  At time 9s, call RecomputeRoutingTables() and traffic will flow again
//    through the path n1-n6
//  At time 10s, stop the first flow.  
//  At time 11s, start a new flow, but to n6's other IP address (the one
//    on the n1/n6 p2p link)
//  At time 12s, bring the n1 interface down between n1 and n6.  Packets
//    will start to be dropped 
//  At time 13s, call RecomputeRoutingTables() and traffic will
//    start flowing again on the alternate path
//  At time 14s, re-enable the n1/n6 interface to up.  Will not change routing
//  At time 15s, call RecomputeRoutingTables() and traffic will start flowing 
//    again on the original path
//  At time 16s, stop the second flow.  

// - Tracing of queues and packet receptions to file "dynamic-global-routing.tr"

#include <iostream>
#include <fstream>
#include <string>
#include <cassert>

#include "ns3/core-module.h"
#include "ns3/simulator-module.h"
#include "ns3/node-module.h"
#include "ns3/helper-module.h"
#include "ns3/global-route-manager.h"

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("DynamicGlobalRoutingExample");

int 
main (int argc, char *argv[])
{
  // Allow the user to override any of the defaults and the above
  // Bind ()s at run-time, via command-line arguments
  CommandLine cmd;
  cmd.Parse (argc, argv);

  NS_LOG_INFO ("Create nodes.");
  NodeContainer c;
  c.Create (7);
  NodeContainer n0n2 = NodeContainer (c.Get (0), c.Get (2));
  NodeContainer n1n2 = NodeContainer (c.Get (1), c.Get (2));
  NodeContainer n5n6 = NodeContainer (c.Get (5), c.Get (6));
  NodeContainer n1n6 = NodeContainer (c.Get (1), c.Get (6));
  NodeContainer n2345 = NodeContainer (c.Get (2), c.Get (3), c.Get (4), c.Get (5));

  InternetStackHelper internet;
  internet.Install (c);

  // We create the channels first without any IP addressing information
  NS_LOG_INFO ("Create channels.");
  PointToPointHelper p2p;
  p2p.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
  p2p.SetChannelAttribute ("Delay", StringValue ("2ms"));
  NetDeviceContainer d0d2 = p2p.Install (n0n2);
  NetDeviceContainer d1d6 = p2p.Install (n1n6);

  NetDeviceContainer d1d2 = p2p.Install (n1n2);

  p2p.SetDeviceAttribute ("DataRate", StringValue ("1500kbps"));
  p2p.SetChannelAttribute ("Delay", StringValue ("10ms"));
  NetDeviceContainer d5d6 = p2p.Install (n5n6);

  // We create the channels first without any IP addressing information
  CsmaHelper csma;
  csma.SetChannelAttribute ("DataRate", StringValue ("5Mbps"));
  csma.SetChannelAttribute ("Delay", StringValue ("2ms"));
  NetDeviceContainer d2345 = csma.Install (n2345);
  
  // Later, we add IP addresses.  
  NS_LOG_INFO ("Assign IP Addresses.");
  Ipv4AddressHelper ipv4;
  ipv4.SetBase ("10.1.1.0", "255.255.255.0");
  ipv4.Assign (d0d2);

  ipv4.SetBase ("10.1.2.0", "255.255.255.0");
  ipv4.Assign (d1d2);

  ipv4.SetBase ("10.1.3.0", "255.255.255.0");
  Ipv4InterfaceContainer i5i6 = ipv4.Assign (d5d6);

  ipv4.SetBase ("10.250.1.0", "255.255.255.0");
  ipv4.Assign (d2345);

  ipv4.SetBase ("172.16.1.0", "255.255.255.0");
  Ipv4InterfaceContainer i1i6 = ipv4.Assign (d1d6);

  // Create router nodes, initialize routing database and set up the routing
  // tables in the nodes.
  GlobalRouteManager::PopulateRoutingTables ();

  // Create the OnOff application to send UDP datagrams of size
  // 210 bytes at a rate of 448 Kb/s
  NS_LOG_INFO ("Create Applications.");
  uint16_t port = 9;   // Discard port (RFC 863)
  OnOffHelper onoff ("ns3::UdpSocketFactory",
                     InetSocketAddress (i5i6.GetAddress (1), port));
  onoff.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (1)));
  onoff.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
  onoff.SetAttribute ("DataRate", StringValue ("2kbps"));
  onoff.SetAttribute ("PacketSize", UintegerValue (50));

  ApplicationContainer apps = onoff.Install (c.Get (1));
  apps.Start (Seconds (1.0));
  apps.Stop (Seconds (10.0));

  // Create a second OnOff application to send UDP datagrams of size
  // 210 bytes at a rate of 448 Kb/s
  OnOffHelper onoff2 ("ns3::UdpSocketFactory",
                     InetSocketAddress (i1i6.GetAddress (1), port));
  onoff2.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (1)));
  onoff2.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
  onoff2.SetAttribute ("DataRate", StringValue ("2kbps"));
  onoff2.SetAttribute ("PacketSize", UintegerValue (50));

  ApplicationContainer apps2 = onoff2.Install (c.Get (1));
  apps2.Start (Seconds (11.0));
  apps2.Stop (Seconds (16.0));

  // Create an optional packet sink to receive these packets
  PacketSinkHelper sink ("ns3::UdpSocketFactory",
    Address (InetSocketAddress (Ipv4Address::GetAny (), port)));
  apps = sink.Install (c.Get (6));
  apps.Start (Seconds (1.0));
  apps.Stop (Seconds (10.0));

  PacketSinkHelper sink2 ("ns3::UdpSocketFactory",
    Address (InetSocketAddress (Ipv4Address::GetAny (), port)));
  apps2 = sink2.Install (c.Get (6));
  apps2.Start (Seconds (11.0));
  apps2.Stop (Seconds (16.0));


  std::ofstream ascii;
  ascii.open ("dynamic-global-routing.tr");
  PointToPointHelper::EnablePcapAll ("dynamic-global-routing");
  PointToPointHelper::EnableAsciiAll (ascii);
  CsmaHelper::EnablePcapAll ("dynamic-global-routing");
  CsmaHelper::EnableAsciiAll (ascii);
  InternetStackHelper::EnableAsciiAll (ascii);
 
  Ptr<Node> n1 = c.Get (1);
  Ptr<Ipv4> ipv41 = n1->GetObject<Ipv4> ();
  // The first ifIndex is 0 for loopback, then the first p2p is numbered 1,
  // then the next p2p is numbered 2
  uint32_t ipv4ifIndex1 = 2;

  Simulator::Schedule (Seconds (2),&Ipv4::SetDown,ipv41, ipv4ifIndex1);
  Simulator::Schedule (Seconds (3),&GlobalRouteManager::RecomputeRoutingTables);
  Simulator::Schedule (Seconds (4),&Ipv4::SetUp,ipv41, ipv4ifIndex1);
  Simulator::Schedule (Seconds (5),&GlobalRouteManager::RecomputeRoutingTables);

  Ptr<Node> n6 = c.Get (6);
  Ptr<Ipv4> ipv46 = n6->GetObject<Ipv4> ();
  // The first ifIndex is 0 for loopback, then the first p2p is numbered 1,
  // then the next p2p is numbered 2
  uint32_t ipv4ifIndex6 = 2;
  Simulator::Schedule (Seconds (6),&Ipv4::SetDown,ipv46, ipv4ifIndex6);
  Simulator::Schedule (Seconds (7),&GlobalRouteManager::RecomputeRoutingTables);
  Simulator::Schedule (Seconds (8),&Ipv4::SetUp,ipv46, ipv4ifIndex6);
  Simulator::Schedule (Seconds (9),&GlobalRouteManager::RecomputeRoutingTables);

  Simulator::Schedule (Seconds (12),&Ipv4::SetDown,ipv41, ipv4ifIndex1);
  Simulator::Schedule (Seconds (13),&GlobalRouteManager::RecomputeRoutingTables);
  Simulator::Schedule (Seconds (14),&Ipv4::SetUp,ipv41, ipv4ifIndex1);
  Simulator::Schedule (Seconds (15),&GlobalRouteManager::RecomputeRoutingTables);

  NS_LOG_INFO ("Run Simulation.");
  Simulator::Run ();
  Simulator::Destroy ();
  NS_LOG_INFO ("Done.");
}