aodv-routing-protocol.cc

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2009 IITP RAS
 *
 * 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
 *
 * Based on 
 *      NS-2 AODV model developed by the CMU/MONARCH group and optimized and
 *      tuned by Samir Das and Mahesh Marina, University of Cincinnati;
 * 
 *      AODV-UU implementation by Erik Nordström of Uppsala University
 *      http://core.it.uu.se/core/index.php/AODV-UU
 *
 * Authors: Elena Buchatskaia <borovkovaes@iitp.ru>
 *          Pavel Boyko <boyko@iitp.ru>
 */
#define NS_LOG_APPEND_CONTEXT                                   \
  if (m_ipv4) { std::clog << "[node " << m_ipv4->GetObject<Node> ()->GetId () << "] "; } 

#include "aodv-routing-protocol.h"
#include "ns3/log.h"
#include "ns3/boolean.h"
#include "ns3/random-variable-stream.h"
#include "ns3/inet-socket-address.h"
#include "ns3/trace-source-accessor.h"
#include "ns3/udp-socket-factory.h"
#include "ns3/wifi-net-device.h"
#include "ns3/adhoc-wifi-mac.h"
#include "ns3/string.h"
#include "ns3/pointer.h"
#include <algorithm>
#include <limits>

NS_LOG_COMPONENT_DEFINE ("AodvRoutingProtocol");

namespace ns3
{
namespace aodv
{
NS_OBJECT_ENSURE_REGISTERED (RoutingProtocol);

const uint32_t RoutingProtocol::AODV_PORT = 654;

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

class DeferredRouteOutputTag : public Tag
{

public:
  DeferredRouteOutputTag (int32_t o = -1) : Tag (), m_oif (o) {}

  static TypeId GetTypeId ()
  {
    static TypeId tid = TypeId ("ns3::aodv::DeferredRouteOutputTag").SetParent<Tag> ()
      .SetParent<Tag> ()
      .AddConstructor<DeferredRouteOutputTag> ()
    ;
    return tid;
  }

  TypeId  GetInstanceTypeId () const 
  {
    return GetTypeId ();
  }

  int32_t GetInterface() const
  {
    return m_oif;
  }

  void SetInterface(int32_t oif)
  {
    m_oif = oif;
  }

  uint32_t GetSerializedSize () const
  {
    return sizeof(int32_t);
  }

  void  Serialize (TagBuffer i) const
  {
    i.WriteU32 (m_oif);
  }

  void  Deserialize (TagBuffer i)
  {
    m_oif = i.ReadU32 ();
  }

  void  Print (std::ostream &os) const
  {
    os << "DeferredRouteOutputTag: output interface = " << m_oif;
  }

private:
  int32_t m_oif;
};

NS_OBJECT_ENSURE_REGISTERED (DeferredRouteOutputTag);


//-----------------------------------------------------------------------------
RoutingProtocol::RoutingProtocol () :
  RreqRetries (2),
  RreqRateLimit (10),
  RerrRateLimit (10),
  ActiveRouteTimeout (Seconds (3)),
  NetDiameter (35),
  NodeTraversalTime (MilliSeconds (40)),
  NetTraversalTime (Time ((2 * NetDiameter) * NodeTraversalTime)),
  PathDiscoveryTime ( Time (2 * NetTraversalTime)),
  MyRouteTimeout (Time (2 * std::max (PathDiscoveryTime, ActiveRouteTimeout))),
  HelloInterval (Seconds (1)),
  AllowedHelloLoss (2),
  DeletePeriod (Time (5 * std::max (ActiveRouteTimeout, HelloInterval))),
  NextHopWait (NodeTraversalTime + MilliSeconds (10)),
  BlackListTimeout (Time (RreqRetries * NetTraversalTime)),
  MaxQueueLen (64),
  MaxQueueTime (Seconds (30)),
  DestinationOnly (false),
  GratuitousReply (true),
  EnableHello (false),
  m_routingTable (DeletePeriod),
  m_queue (MaxQueueLen, MaxQueueTime),
  m_requestId (0),
  m_seqNo (0),
  m_rreqIdCache (PathDiscoveryTime),
  m_dpd (PathDiscoveryTime),
  m_nb (HelloInterval),
  m_rreqCount (0),
  m_rerrCount (0),
  m_htimer (Timer::CANCEL_ON_DESTROY),
  m_rreqRateLimitTimer (Timer::CANCEL_ON_DESTROY),
  m_rerrRateLimitTimer (Timer::CANCEL_ON_DESTROY),
  m_lastBcastTime (Seconds (0))
{
  m_nb.SetCallback (MakeCallback (&RoutingProtocol::SendRerrWhenBreaksLinkToNextHop, this));
}

TypeId
RoutingProtocol::GetTypeId (void)
{
  static TypeId tid = TypeId ("ns3::aodv::RoutingProtocol")
    .SetParent<Ipv4RoutingProtocol> ()
    .AddConstructor<RoutingProtocol> ()
    .AddAttribute ("HelloInterval", "HELLO messages emission interval.",
                   TimeValue (Seconds (1)),
                   MakeTimeAccessor (&RoutingProtocol::HelloInterval),
                   MakeTimeChecker ())
    .AddAttribute ("RreqRetries", "Maximum number of retransmissions of RREQ to discover a route",
                   UintegerValue (2),
                   MakeUintegerAccessor (&RoutingProtocol::RreqRetries),
                   MakeUintegerChecker<uint32_t> ())
    .AddAttribute ("RreqRateLimit", "Maximum number of RREQ per second.",
                   UintegerValue (10),
                   MakeUintegerAccessor (&RoutingProtocol::RreqRateLimit),
                   MakeUintegerChecker<uint32_t> ())
    .AddAttribute ("RerrRateLimit", "Maximum number of RERR per second.",
                   UintegerValue (10),
                   MakeUintegerAccessor (&RoutingProtocol::RerrRateLimit),
                   MakeUintegerChecker<uint32_t> ())
    .AddAttribute ("NodeTraversalTime", "Conservative estimate of the average one hop traversal time for packets and should include "
                   "queuing delays, interrupt processing times and transfer times.",
                   TimeValue (MilliSeconds (40)),
                   MakeTimeAccessor (&RoutingProtocol::NodeTraversalTime),
                   MakeTimeChecker ())
    .AddAttribute ("NextHopWait", "Period of our waiting for the neighbour's RREP_ACK = 10 ms + NodeTraversalTime",
                   TimeValue (MilliSeconds (50)),
                   MakeTimeAccessor (&RoutingProtocol::NextHopWait),
                   MakeTimeChecker ())
    .AddAttribute ("ActiveRouteTimeout", "Period of time during which the route is considered to be valid",
                   TimeValue (Seconds (3)),
                   MakeTimeAccessor (&RoutingProtocol::ActiveRouteTimeout),
                   MakeTimeChecker ())
    .AddAttribute ("MyRouteTimeout", "Value of lifetime field in RREP generating by this node = 2 * max(ActiveRouteTimeout, PathDiscoveryTime)",
                   TimeValue (Seconds (11.2)),
                   MakeTimeAccessor (&RoutingProtocol::MyRouteTimeout),
                   MakeTimeChecker ())
    .AddAttribute ("BlackListTimeout", "Time for which the node is put into the blacklist = RreqRetries * NetTraversalTime",
                   TimeValue (Seconds (5.6)),
                   MakeTimeAccessor (&RoutingProtocol::BlackListTimeout),
                   MakeTimeChecker ())
    .AddAttribute ("DeletePeriod", "DeletePeriod is intended to provide an upper bound on the time for which an upstream node A "
                   "can have a neighbor B as an active next hop for destination D, while B has invalidated the route to D."
                   " = 5 * max (HelloInterval, ActiveRouteTimeout)",
                   TimeValue (Seconds (15)),
                   MakeTimeAccessor (&RoutingProtocol::DeletePeriod),
                   MakeTimeChecker ())
    .AddAttribute ("NetDiameter", "Net diameter measures the maximum possible number of hops between two nodes in the network",
                   UintegerValue (35),
                   MakeUintegerAccessor (&RoutingProtocol::NetDiameter),
                   MakeUintegerChecker<uint32_t> ())
    .AddAttribute ("NetTraversalTime", "Estimate of the average net traversal time = 2 * NodeTraversalTime * NetDiameter",
                   TimeValue (Seconds (2.8)),
                   MakeTimeAccessor (&RoutingProtocol::NetTraversalTime),
                   MakeTimeChecker ())
    .AddAttribute ("PathDiscoveryTime", "Estimate of maximum time needed to find route in network = 2 * NetTraversalTime",
                   TimeValue (Seconds (5.6)),
                   MakeTimeAccessor (&RoutingProtocol::PathDiscoveryTime),
                   MakeTimeChecker ())
    .AddAttribute ("MaxQueueLen", "Maximum number of packets that we allow a routing protocol to buffer.",
                   UintegerValue (64),
                   MakeUintegerAccessor (&RoutingProtocol::SetMaxQueueLen,
                                         &RoutingProtocol::GetMaxQueueLen),
                   MakeUintegerChecker<uint32_t> ())
    .AddAttribute ("MaxQueueTime", "Maximum time packets can be queued (in seconds)",
                   TimeValue (Seconds (30)),
                   MakeTimeAccessor (&RoutingProtocol::SetMaxQueueTime,
                                     &RoutingProtocol::GetMaxQueueTime),
                   MakeTimeChecker ())
    .AddAttribute ("AllowedHelloLoss", "Number of hello messages which may be loss for valid link.",
                   UintegerValue (2),
                   MakeUintegerAccessor (&RoutingProtocol::AllowedHelloLoss),
                   MakeUintegerChecker<uint16_t> ())
    .AddAttribute ("GratuitousReply", "Indicates whether a gratuitous RREP should be unicast to the node originated route discovery.",
                   BooleanValue (true),
                   MakeBooleanAccessor (&RoutingProtocol::SetGratuitousReplyFlag,
                                        &RoutingProtocol::GetGratuitousReplyFlag),
                   MakeBooleanChecker ())
    .AddAttribute ("DestinationOnly", "Indicates only the destination may respond to this RREQ.",
                   BooleanValue (false),
                   MakeBooleanAccessor (&RoutingProtocol::SetDesinationOnlyFlag,
                                        &RoutingProtocol::GetDesinationOnlyFlag),
                   MakeBooleanChecker ())
    .AddAttribute ("EnableHello", "Indicates whether a hello messages enable.",
                   BooleanValue (true),
                   MakeBooleanAccessor (&RoutingProtocol::SetHelloEnable,
                                        &RoutingProtocol::GetHelloEnable),
                   MakeBooleanChecker ())
    .AddAttribute ("EnableBroadcast", "Indicates whether a broadcast data packets forwarding enable.",
                   BooleanValue (true),
                   MakeBooleanAccessor (&RoutingProtocol::SetBroadcastEnable,
                                        &RoutingProtocol::GetBroadcastEnable),
                   MakeBooleanChecker ())
    .AddAttribute ("UniformRv",
                   "Access to the underlying UniformRandomVariable",
                   StringValue ("ns3::UniformRandomVariable"),
                   MakePointerAccessor (&RoutingProtocol::m_uniformRandomVariable),
                   MakePointerChecker<UniformRandomVariable> ())
  ;
  return tid;
}

void
RoutingProtocol::SetMaxQueueLen (uint32_t len)
{
  MaxQueueLen = len;
  m_queue.SetMaxQueueLen (len);
}
void
RoutingProtocol::SetMaxQueueTime (Time t)
{
  MaxQueueTime = t;
  m_queue.SetQueueTimeout (t);
}

RoutingProtocol::~RoutingProtocol ()
{
}

void
RoutingProtocol::DoDispose ()
{
  m_ipv4 = 0;
  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::iterator iter =
         m_socketAddresses.begin (); iter != m_socketAddresses.end (); iter++)
    {
      iter->first->Close ();
    }
  m_socketAddresses.clear ();
  Ipv4RoutingProtocol::DoDispose ();
}

void
RoutingProtocol::PrintRoutingTable (Ptr<OutputStreamWrapper> stream) const
{
  *stream->GetStream () << "Node: " << m_ipv4->GetObject<Node> ()->GetId () << " Time: " << Simulator::Now ().GetSeconds () << "s ";
  m_routingTable.Print (stream);
}

int64_t
RoutingProtocol::AssignStreams (int64_t stream)
{
  NS_LOG_FUNCTION (this << stream);
  m_uniformRandomVariable->SetStream (stream);
  return 1;
}

void
RoutingProtocol::Start ()
{
  NS_LOG_FUNCTION (this);
  if (EnableHello)
    {
      m_nb.ScheduleTimer ();
    }
  m_rreqRateLimitTimer.SetFunction (&RoutingProtocol::RreqRateLimitTimerExpire,
                                    this);
  m_rreqRateLimitTimer.Schedule (Seconds (1));

  m_rerrRateLimitTimer.SetFunction (&RoutingProtocol::RerrRateLimitTimerExpire,
                                    this);
  m_rerrRateLimitTimer.Schedule (Seconds (1));

}

Ptr<Ipv4Route>
RoutingProtocol::RouteOutput (Ptr<Packet> p, const Ipv4Header &header,
                              Ptr<NetDevice> oif, Socket::SocketErrno &sockerr)
{
  NS_LOG_FUNCTION (this << header << (oif ? oif->GetIfIndex () : 0));
  if (!p)
    {
      NS_LOG_DEBUG("Packet is == 0");
      return LoopbackRoute (header, oif); // later
    }
  if (m_socketAddresses.empty ())
    {
      sockerr = Socket::ERROR_NOROUTETOHOST;
      NS_LOG_LOGIC ("No aodv interfaces");
      Ptr<Ipv4Route> route;
      return route;
    }
  sockerr = Socket::ERROR_NOTERROR;
  Ptr<Ipv4Route> route;
  Ipv4Address dst = header.GetDestination ();
  RoutingTableEntry rt;
  if (m_routingTable.LookupValidRoute (dst, rt))
    {
      route = rt.GetRoute ();
      NS_ASSERT (route != 0);
      NS_LOG_DEBUG ("Exist route to " << route->GetDestination () << " from interface " << route->GetSource ());
      if (oif != 0 && route->GetOutputDevice () != oif)
        {
          NS_LOG_DEBUG ("Output device doesn't match. Dropped.");
          sockerr = Socket::ERROR_NOROUTETOHOST;
          return Ptr<Ipv4Route> ();
        }
      UpdateRouteLifeTime (dst, ActiveRouteTimeout);
      UpdateRouteLifeTime (route->GetGateway (), ActiveRouteTimeout);
      return route;
    }

  // Valid route not found, in this case we return loopback. 
  // Actual route request will be deferred until packet will be fully formed, 
  // routed to loopback, received from loopback and passed to RouteInput (see below)
  uint32_t iif = (oif ? m_ipv4->GetInterfaceForDevice (oif) : -1);
  DeferredRouteOutputTag tag (iif);
  NS_LOG_DEBUG ("Valid Route not found");
  if (!p->PeekPacketTag (tag))
    {
      p->AddPacketTag (tag);
    }
  return LoopbackRoute (header, oif);
}

void
RoutingProtocol::DeferredRouteOutput (Ptr<const Packet> p, const Ipv4Header & header, 
                                      UnicastForwardCallback ucb, ErrorCallback ecb)
{
  NS_LOG_FUNCTION (this << p << header);
  NS_ASSERT (p != 0 && p != Ptr<Packet> ());

  QueueEntry newEntry (p, header, ucb, ecb);
  bool result = m_queue.Enqueue (newEntry);
  if (result)
    {
      NS_LOG_LOGIC ("Add packet " << p->GetUid () << " to queue. Protocol " << (uint16_t) header.GetProtocol ());
      RoutingTableEntry rt;
      bool result = m_routingTable.LookupRoute (header.GetDestination (), rt);
      if(!result || ((rt.GetFlag () != IN_SEARCH) && result))
        {
          NS_LOG_LOGIC ("Send new RREQ for outbound packet to " <<header.GetDestination ());
          SendRequest (header.GetDestination ());
        }
    }
}

bool
RoutingProtocol::RouteInput (Ptr<const Packet> p, const Ipv4Header &header,
                             Ptr<const NetDevice> idev, UnicastForwardCallback ucb,
                             MulticastForwardCallback mcb, LocalDeliverCallback lcb, ErrorCallback ecb)
{
  NS_LOG_FUNCTION (this << p->GetUid () << header.GetDestination () << idev->GetAddress ());
  if (m_socketAddresses.empty ())
    {
      NS_LOG_LOGIC ("No aodv interfaces");
      return false;
    }
  NS_ASSERT (m_ipv4 != 0);
  NS_ASSERT (p != 0);
  // Check if input device supports IP
  NS_ASSERT (m_ipv4->GetInterfaceForDevice (idev) >= 0);
  int32_t iif = m_ipv4->GetInterfaceForDevice (idev);

  Ipv4Address dst = header.GetDestination ();
  Ipv4Address origin = header.GetSource ();

  // Deferred route request
  if (idev == m_lo)
    {
      DeferredRouteOutputTag tag;
      if (p->PeekPacketTag (tag))
        {
          DeferredRouteOutput (p, header, ucb, ecb);
          return true;
        }
    }

  // Duplicate of own packet
  if (IsMyOwnAddress (origin))
    return true;

  // AODV is not a multicast routing protocol
  if (dst.IsMulticast ())
    {
      return false; 
    }

  // Broadcast local delivery/forwarding
  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j =
         m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
    {
      Ipv4InterfaceAddress iface = j->second;
      if (m_ipv4->GetInterfaceForAddress (iface.GetLocal ()) == iif)
        if (dst == iface.GetBroadcast () || dst.IsBroadcast ())
          {
            if (m_dpd.IsDuplicate (p, header))
              {
                NS_LOG_DEBUG ("Duplicated packet " << p->GetUid () << " from " << origin << ". Drop.");
                return true;
              }
            UpdateRouteLifeTime (origin, ActiveRouteTimeout);
            Ptr<Packet> packet = p->Copy ();
            if (lcb.IsNull () == false)
              {
                NS_LOG_LOGIC ("Broadcast local delivery to " << iface.GetLocal ());
                lcb (p, header, iif);
                // Fall through to additional processing
              }
            else
              {
                NS_LOG_ERROR ("Unable to deliver packet locally due to null callback " << p->GetUid () << " from " << origin);
                ecb (p, header, Socket::ERROR_NOROUTETOHOST);
              }
            if (!EnableBroadcast)
              {
                return true;
              }
            if (header.GetTtl () > 1)
              {
                NS_LOG_LOGIC ("Forward broadcast. TTL " << (uint16_t) header.GetTtl ());
                RoutingTableEntry toBroadcast;
                if (m_routingTable.LookupRoute (dst, toBroadcast))
                  {
                    Ptr<Ipv4Route> route = toBroadcast.GetRoute ();
                    ucb (route, packet, header);
                  }
                else
                  {
                    NS_LOG_DEBUG ("No route to forward broadcast. Drop packet " << p->GetUid ());
                  }
              }
            else
              {
                NS_LOG_DEBUG ("TTL exceeded. Drop packet " << p->GetUid ());
              }
            return true;
          }
    }

  // Unicast local delivery
  if (m_ipv4->IsDestinationAddress (dst, iif))
    {
      UpdateRouteLifeTime (origin, ActiveRouteTimeout);
      RoutingTableEntry toOrigin;
      if (m_routingTable.LookupValidRoute (origin, toOrigin))
        {
          UpdateRouteLifeTime (toOrigin.GetNextHop (), ActiveRouteTimeout);
          m_nb.Update (toOrigin.GetNextHop (), ActiveRouteTimeout);
        }
      if (lcb.IsNull () == false)
        {
          NS_LOG_LOGIC ("Unicast local delivery to " << dst);
          lcb (p, header, iif);
        }
      else
        {
          NS_LOG_ERROR ("Unable to deliver packet locally due to null callback " << p->GetUid () << " from " << origin);
          ecb (p, header, Socket::ERROR_NOROUTETOHOST);
        }
      return true;
    }

  // Forwarding
  return Forwarding (p, header, ucb, ecb);
}

bool
RoutingProtocol::Forwarding (Ptr<const Packet> p, const Ipv4Header & header,
                             UnicastForwardCallback ucb, ErrorCallback ecb)
{
  NS_LOG_FUNCTION (this);
  Ipv4Address dst = header.GetDestination ();
  Ipv4Address origin = header.GetSource ();
  m_routingTable.Purge ();
  RoutingTableEntry toDst;
  if (m_routingTable.LookupRoute (dst, toDst))
    {
      if (toDst.GetFlag () == VALID)
        {
          Ptr<Ipv4Route> route = toDst.GetRoute ();
          NS_LOG_LOGIC (route->GetSource ()<<" forwarding to " << dst << " from " << origin << " packet " << p->GetUid ());

          /*
           *  Each time a route is used to forward a data packet, its Active Route
           *  Lifetime field of the source, destination and the next hop on the
           *  path to the destination is updated to be no less than the current
           *  time plus ActiveRouteTimeout.
           */
          UpdateRouteLifeTime (origin, ActiveRouteTimeout);
          UpdateRouteLifeTime (dst, ActiveRouteTimeout);
          UpdateRouteLifeTime (route->GetGateway (), ActiveRouteTimeout);
          /*
           *  Since the route between each originator and destination pair is expected to be symmetric, the
           *  Active Route Lifetime for the previous hop, along the reverse path back to the IP source, is also updated
           *  to be no less than the current time plus ActiveRouteTimeout
           */
          RoutingTableEntry toOrigin;
          m_routingTable.LookupRoute (origin, toOrigin);
          UpdateRouteLifeTime (toOrigin.GetNextHop (), ActiveRouteTimeout);

          m_nb.Update (route->GetGateway (), ActiveRouteTimeout);
          m_nb.Update (toOrigin.GetNextHop (), ActiveRouteTimeout);

          ucb (route, p, header);
          return true;
        }
      else
        {
          if (toDst.GetValidSeqNo ())
            {
              SendRerrWhenNoRouteToForward (dst, toDst.GetSeqNo (), origin);
              NS_LOG_DEBUG ("Drop packet " << p->GetUid () << " because no route to forward it.");
              return false;
            }
        }
    }
  NS_LOG_LOGIC ("route not found to "<< dst << ". Send RERR message.");
  NS_LOG_DEBUG ("Drop packet " << p->GetUid () << " because no route to forward it.");
  SendRerrWhenNoRouteToForward (dst, 0, origin);
  return false;
}

void
RoutingProtocol::SetIpv4 (Ptr<Ipv4> ipv4)
{
  NS_ASSERT (ipv4 != 0);
  NS_ASSERT (m_ipv4 == 0);

  if (EnableHello)
    {
      m_htimer.SetFunction (&RoutingProtocol::HelloTimerExpire, this);
      m_htimer.Schedule (MilliSeconds (m_uniformRandomVariable->GetInteger (0, 100)));
    }

  m_ipv4 = ipv4;

  // Create lo route. It is asserted that the only one interface up for now is loopback
  NS_ASSERT (m_ipv4->GetNInterfaces () == 1 && m_ipv4->GetAddress (0, 0).GetLocal () == Ipv4Address ("127.0.0.1"));
  m_lo = m_ipv4->GetNetDevice (0);
  NS_ASSERT (m_lo != 0);
  // Remember lo route
  RoutingTableEntry rt (/*device=*/ m_lo, /*dst=*/ Ipv4Address::GetLoopback (), /*know seqno=*/ true, /*seqno=*/ 0,
                                    /*iface=*/ Ipv4InterfaceAddress (Ipv4Address::GetLoopback (), Ipv4Mask ("255.0.0.0")),
                                    /*hops=*/ 1, /*next hop=*/ Ipv4Address::GetLoopback (),
                                    /*lifetime=*/ Simulator::GetMaximumSimulationTime ());
  m_routingTable.AddRoute (rt);

  Simulator::ScheduleNow (&RoutingProtocol::Start, this);
}

void
RoutingProtocol::NotifyInterfaceUp (uint32_t i)
{
  NS_LOG_FUNCTION (this << m_ipv4->GetAddress (i, 0).GetLocal ());
  Ptr<Ipv4L3Protocol> l3 = m_ipv4->GetObject<Ipv4L3Protocol> ();
  if (l3->GetNAddresses (i) > 1)
    {
      NS_LOG_WARN ("AODV does not work with more then one address per each interface.");
    }
  Ipv4InterfaceAddress iface = l3->GetAddress (i, 0);
  if (iface.GetLocal () == Ipv4Address ("127.0.0.1"))
    return;
 
  // Create a socket to listen only on this interface
  Ptr<Socket> socket = Socket::CreateSocket (GetObject<Node> (),
                                             UdpSocketFactory::GetTypeId ());
  NS_ASSERT (socket != 0);
  socket->SetRecvCallback (MakeCallback (&RoutingProtocol::RecvAodv, this));
  socket->BindToNetDevice (l3->GetNetDevice (i));
  socket->Bind (InetSocketAddress (Ipv4Address::GetAny (), AODV_PORT));
  socket->SetAllowBroadcast (true);
  socket->SetAttribute ("IpTtl", UintegerValue (1));
  m_socketAddresses.insert (std::make_pair (socket, iface));

  // Add local broadcast record to the routing table
  Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (iface.GetLocal ()));
  RoutingTableEntry rt (/*device=*/ dev, /*dst=*/ iface.GetBroadcast (), /*know seqno=*/ true, /*seqno=*/ 0, /*iface=*/ iface,
                                    /*hops=*/ 1, /*next hop=*/ iface.GetBroadcast (), /*lifetime=*/ Simulator::GetMaximumSimulationTime ());
  m_routingTable.AddRoute (rt);

  // Allow neighbor manager use this interface for layer 2 feedback if possible
  Ptr<WifiNetDevice> wifi = dev->GetObject<WifiNetDevice> ();
  if (wifi == 0)
    return;
  Ptr<WifiMac> mac = wifi->GetMac ();
  if (mac == 0)
    return;

  mac->TraceConnectWithoutContext ("TxErrHeader", m_nb.GetTxErrorCallback ());
  m_nb.AddArpCache (l3->GetInterface (i)->GetArpCache ());
}

void
RoutingProtocol::NotifyInterfaceDown (uint32_t i)
{
  NS_LOG_FUNCTION (this << m_ipv4->GetAddress (i, 0).GetLocal ());

  // Disable layer 2 link state monitoring (if possible)
  Ptr<Ipv4L3Protocol> l3 = m_ipv4->GetObject<Ipv4L3Protocol> ();
  Ptr<NetDevice> dev = l3->GetNetDevice (i);
  Ptr<WifiNetDevice> wifi = dev->GetObject<WifiNetDevice> ();
  if (wifi != 0)
    {
      Ptr<WifiMac> mac = wifi->GetMac ()->GetObject<AdhocWifiMac> ();
      if (mac != 0)
        {
          mac->TraceDisconnectWithoutContext ("TxErrHeader",
                                              m_nb.GetTxErrorCallback ());
          m_nb.DelArpCache (l3->GetInterface (i)->GetArpCache ());
        }
    }

  // Close socket 
  Ptr<Socket> socket = FindSocketWithInterfaceAddress (m_ipv4->GetAddress (i, 0));
  NS_ASSERT (socket);
  socket->Close ();
  m_socketAddresses.erase (socket);
  if (m_socketAddresses.empty ())
    {
      NS_LOG_LOGIC ("No aodv interfaces");
      m_htimer.Cancel ();
      m_nb.Clear ();
      m_routingTable.Clear ();
      return;
    }
  m_routingTable.DeleteAllRoutesFromInterface (m_ipv4->GetAddress (i, 0));
}

void
RoutingProtocol::NotifyAddAddress (uint32_t i, Ipv4InterfaceAddress address)
{
  NS_LOG_FUNCTION (this << " interface " << i << " address " << address);
  Ptr<Ipv4L3Protocol> l3 = m_ipv4->GetObject<Ipv4L3Protocol> ();
  if (!l3->IsUp (i))
    return;
  if (l3->GetNAddresses (i) == 1)
    {
      Ipv4InterfaceAddress iface = l3->GetAddress (i, 0);
      Ptr<Socket> socket = FindSocketWithInterfaceAddress (iface);
      if (!socket)
        {
          if (iface.GetLocal () == Ipv4Address ("127.0.0.1"))
            return;
          // Create a socket to listen only on this interface
          Ptr<Socket> socket = Socket::CreateSocket (GetObject<Node> (),
                                                     UdpSocketFactory::GetTypeId ());
          NS_ASSERT (socket != 0);
          socket->SetRecvCallback (MakeCallback (&RoutingProtocol::RecvAodv,this));
          socket->BindToNetDevice (l3->GetNetDevice (i));
          // Bind to any IP address so that broadcasts can be received
          socket->Bind (InetSocketAddress (Ipv4Address::GetAny (), AODV_PORT));
          socket->SetAllowBroadcast (true);
          m_socketAddresses.insert (std::make_pair (socket, iface));

          // Add local broadcast record to the routing table
          Ptr<NetDevice> dev = m_ipv4->GetNetDevice (
              m_ipv4->GetInterfaceForAddress (iface.GetLocal ()));
          RoutingTableEntry rt (/*device=*/ dev, /*dst=*/ iface.GetBroadcast (), /*know seqno=*/ true,
                                            /*seqno=*/ 0, /*iface=*/ iface, /*hops=*/ 1,
                                            /*next hop=*/ iface.GetBroadcast (), /*lifetime=*/ Simulator::GetMaximumSimulationTime ());
          m_routingTable.AddRoute (rt);
        }
    }
  else
    {
      NS_LOG_LOGIC ("AODV does not work with more then one address per each interface. Ignore added address");
    }
}

void
RoutingProtocol::NotifyRemoveAddress (uint32_t i, Ipv4InterfaceAddress address)
{
  NS_LOG_FUNCTION (this);
  Ptr<Socket> socket = FindSocketWithInterfaceAddress (address);
  if (socket)
    {
      m_routingTable.DeleteAllRoutesFromInterface (address);
      m_socketAddresses.erase (socket);
      Ptr<Ipv4L3Protocol> l3 = m_ipv4->GetObject<Ipv4L3Protocol> ();
      if (l3->GetNAddresses (i))
        {
          Ipv4InterfaceAddress iface = l3->GetAddress (i, 0);
          // Create a socket to listen only on this interface
          Ptr<Socket> socket = Socket::CreateSocket (GetObject<Node> (),
                                                     UdpSocketFactory::GetTypeId ());
          NS_ASSERT (socket != 0);
          socket->SetRecvCallback (MakeCallback (&RoutingProtocol::RecvAodv, this));
          // Bind to any IP address so that broadcasts can be received
          socket->Bind (InetSocketAddress (Ipv4Address::GetAny (), AODV_PORT));
          socket->SetAllowBroadcast (true);
          m_socketAddresses.insert (std::make_pair (socket, iface));

          // Add local broadcast record to the routing table
          Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (iface.GetLocal ()));
          RoutingTableEntry rt (/*device=*/ dev, /*dst=*/ iface.GetBroadcast (), /*know seqno=*/ true, /*seqno=*/ 0, /*iface=*/ iface,
                                            /*hops=*/ 1, /*next hop=*/ iface.GetBroadcast (), /*lifetime=*/ Simulator::GetMaximumSimulationTime ());
          m_routingTable.AddRoute (rt);
        }
      if (m_socketAddresses.empty ())
        {
          NS_LOG_LOGIC ("No aodv interfaces");
          m_htimer.Cancel ();
          m_nb.Clear ();
          m_routingTable.Clear ();
          return;
        }
    }
  else
    {
      NS_LOG_LOGIC ("Remove address not participating in AODV operation");
    }
}

bool
RoutingProtocol::IsMyOwnAddress (Ipv4Address src)
{
  NS_LOG_FUNCTION (this << src);
  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j =
         m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
    {
      Ipv4InterfaceAddress iface = j->second;
      if (src == iface.GetLocal ())
        {
          return true;
        }
    }
  return false;
}

Ptr<Ipv4Route> 
RoutingProtocol::LoopbackRoute (const Ipv4Header & hdr, Ptr<NetDevice> oif) const
{
  NS_LOG_FUNCTION (this << hdr);
  NS_ASSERT (m_lo != 0);
  Ptr<Ipv4Route> rt = Create<Ipv4Route> ();
  rt->SetDestination (hdr.GetDestination ());
  //
  // Source address selection here is tricky.  The loopback route is
  // returned when AODV does not have a route; this causes the packet
  // to be looped back and handled (cached) in RouteInput() method
  // while a route is found. However, connection-oriented protocols
  // like TCP need to create an endpoint four-tuple (src, src port,
  // dst, dst port) and create a pseudo-header for checksumming.  So,
  // AODV needs to guess correctly what the eventual source address
  // will be.
  //
  // For single interface, single address nodes, this is not a problem.
  // When there are possibly multiple outgoing interfaces, the policy
  // implemented here is to pick the first available AODV interface.
  // If RouteOutput() caller specified an outgoing interface, that 
  // further constrains the selection of source address
  //
  std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j = m_socketAddresses.begin ();
  if (oif)
    {
      // Iterate to find an address on the oif device
      for (j = m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
        {
          Ipv4Address addr = j->second.GetLocal ();
          int32_t interface = m_ipv4->GetInterfaceForAddress (addr);
          if (oif == m_ipv4->GetNetDevice (static_cast<uint32_t> (interface)))
            {
              rt->SetSource (addr);
              break;
            }
        }
    }
  else
    {
      rt->SetSource (j->second.GetLocal ());
    }
  NS_ASSERT_MSG (rt->GetSource () != Ipv4Address (), "Valid AODV source address not found");
  rt->SetGateway (Ipv4Address ("127.0.0.1"));
  rt->SetOutputDevice (m_lo);
  return rt;
}

void
RoutingProtocol::SendRequest (Ipv4Address dst)
{
  NS_LOG_FUNCTION ( this << dst);
  // A node SHOULD NOT originate more than RREQ_RATELIMIT RREQ messages per second.
  if (m_rreqCount == RreqRateLimit)
    {
      Simulator::Schedule (m_rreqRateLimitTimer.GetDelayLeft () + MicroSeconds (100),
                           &RoutingProtocol::SendRequest, this, dst);
      return;
    }
  else
    m_rreqCount++;
  // Create RREQ header
  RreqHeader rreqHeader;
  rreqHeader.SetDst (dst);

  RoutingTableEntry rt;
  if (m_routingTable.LookupRoute (dst, rt))
    {
      rreqHeader.SetHopCount (rt.GetHop ());
      if (rt.GetValidSeqNo ())
        rreqHeader.SetDstSeqno (rt.GetSeqNo ());
      else
        rreqHeader.SetUnknownSeqno (true);
      rt.SetFlag (IN_SEARCH);
      m_routingTable.Update (rt);
    }
  else
    {
      rreqHeader.SetUnknownSeqno (true);
      Ptr<NetDevice> dev = 0;
      RoutingTableEntry newEntry (/*device=*/ dev, /*dst=*/ dst, /*validSeqNo=*/ false, /*seqno=*/ 0,
                                              /*iface=*/ Ipv4InterfaceAddress (),/*hop=*/ 0,
                                              /*nextHop=*/ Ipv4Address (), /*lifeTime=*/ Seconds (0));
      newEntry.SetFlag (IN_SEARCH);
      m_routingTable.AddRoute (newEntry);
    }

  if (GratuitousReply)
    rreqHeader.SetGratiousRrep (true);
  if (DestinationOnly)
    rreqHeader.SetDestinationOnly (true);

  m_seqNo++;
  rreqHeader.SetOriginSeqno (m_seqNo);
  m_requestId++;
  rreqHeader.SetId (m_requestId);
  rreqHeader.SetHopCount (0);

  // Send RREQ as subnet directed broadcast from each interface used by aodv
  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j =
         m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
    {
      Ptr<Socket> socket = j->first;
      Ipv4InterfaceAddress iface = j->second;

      rreqHeader.SetOrigin (iface.GetLocal ());
      m_rreqIdCache.IsDuplicate (iface.GetLocal (), m_requestId);

      Ptr<Packet> packet = Create<Packet> ();
      packet->AddHeader (rreqHeader);
      TypeHeader tHeader (AODVTYPE_RREQ);
      packet->AddHeader (tHeader);
      // Send to all-hosts broadcast if on /32 addr, subnet-directed otherwise
      Ipv4Address destination;
      if (iface.GetMask () == Ipv4Mask::GetOnes ())
        {
          destination = Ipv4Address ("255.255.255.255");
        }
      else
        { 
          destination = iface.GetBroadcast ();
        }
      NS_LOG_DEBUG ("Send RREQ with id " << rreqHeader.GetId () << " to socket");
      m_lastBcastTime = Simulator::Now ();
      Simulator::Schedule (Time (MilliSeconds (m_uniformRandomVariable->GetInteger (0, 10))), &RoutingProtocol::SendTo, this, socket, packet, destination); 
    }
  ScheduleRreqRetry (dst);
}

void
RoutingProtocol::SendTo (Ptr<Socket> socket, Ptr<Packet> packet, Ipv4Address destination)
{
    socket->SendTo (packet, 0, InetSocketAddress (destination, AODV_PORT));

}
void
RoutingProtocol::ScheduleRreqRetry (Ipv4Address dst)
{
  NS_LOG_FUNCTION (this << dst);
  if (m_addressReqTimer.find (dst) == m_addressReqTimer.end ())
    {
      Timer timer (Timer::CANCEL_ON_DESTROY);
      m_addressReqTimer[dst] = timer;
    }
  m_addressReqTimer[dst].SetFunction (&RoutingProtocol::RouteRequestTimerExpire, this);
  m_addressReqTimer[dst].Remove ();
  m_addressReqTimer[dst].SetArguments (dst);
  RoutingTableEntry rt;
  m_routingTable.LookupRoute (dst, rt);
  rt.IncrementRreqCnt ();
  m_routingTable.Update (rt);
  m_addressReqTimer[dst].Schedule (Time (rt.GetRreqCnt () * NetTraversalTime));
  NS_LOG_LOGIC ("Scheduled RREQ retry in " << Time (rt.GetRreqCnt () * NetTraversalTime).GetSeconds () << " seconds");
}

void
RoutingProtocol::RecvAodv (Ptr<Socket> socket)
{
  NS_LOG_FUNCTION (this << socket);
  Address sourceAddress;
  Ptr<Packet> packet = socket->RecvFrom (sourceAddress);
  InetSocketAddress inetSourceAddr = InetSocketAddress::ConvertFrom (sourceAddress);
  Ipv4Address sender = inetSourceAddr.GetIpv4 ();
  Ipv4Address receiver = m_socketAddresses[socket].GetLocal ();
  NS_LOG_DEBUG ("AODV node " << this << " received a AODV packet from " << sender << " to " << receiver);

  UpdateRouteToNeighbor (sender, receiver);
  TypeHeader tHeader (AODVTYPE_RREQ);
  packet->RemoveHeader (tHeader);
  if (!tHeader.IsValid ())
    {
      NS_LOG_DEBUG ("AODV message " << packet->GetUid () << " with unknown type received: " << tHeader.Get () << ". Drop");
      return; // drop
    }
  switch (tHeader.Get ())
    {
    case AODVTYPE_RREQ:
      {
        RecvRequest (packet, receiver, sender);
        break;
      }
    case AODVTYPE_RREP:
      {
        RecvReply (packet, receiver, sender);
        break;
      }
    case AODVTYPE_RERR:
      {
        RecvError (packet, sender);
        break;
      }
    case AODVTYPE_RREP_ACK:
      {
        RecvReplyAck (sender);
        break;
      }
    }
}

bool
RoutingProtocol::UpdateRouteLifeTime (Ipv4Address addr, Time lifetime)
{
  NS_LOG_FUNCTION (this << addr << lifetime);
  RoutingTableEntry rt;
  if (m_routingTable.LookupRoute (addr, rt))
    {
      if (rt.GetFlag () == VALID)
        {
          NS_LOG_DEBUG ("Updating VALID route");
          rt.SetRreqCnt (0);
          rt.SetLifeTime (std::max (lifetime, rt.GetLifeTime ()));
          m_routingTable.Update (rt);
          return true;
        }
    }
  return false;
}

void
RoutingProtocol::UpdateRouteToNeighbor (Ipv4Address sender, Ipv4Address receiver)
{
  NS_LOG_FUNCTION (this << "sender " << sender << " receiver " << receiver);
  RoutingTableEntry toNeighbor;
  if (!m_routingTable.LookupRoute (sender, toNeighbor))
    {
      Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver));
      RoutingTableEntry newEntry (/*device=*/ dev, /*dst=*/ sender, /*know seqno=*/ false, /*seqno=*/ 0,
                                              /*iface=*/ m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0),
                                              /*hops=*/ 1, /*next hop=*/ sender, /*lifetime=*/ ActiveRouteTimeout);
      m_routingTable.AddRoute (newEntry);
    }
  else
    {
      Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver));
      if (toNeighbor.GetValidSeqNo () && (toNeighbor.GetHop () == 1) && (toNeighbor.GetOutputDevice () == dev))
        {
          toNeighbor.SetLifeTime (std::max (ActiveRouteTimeout, toNeighbor.GetLifeTime ()));
        }
      else
        {
          RoutingTableEntry newEntry (/*device=*/ dev, /*dst=*/ sender, /*know seqno=*/ false, /*seqno=*/ 0,
                                                  /*iface=*/ m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0),
                                                  /*hops=*/ 1, /*next hop=*/ sender, /*lifetime=*/ std::max (ActiveRouteTimeout, toNeighbor.GetLifeTime ()));
          m_routingTable.Update (newEntry);
        }
    }

}

void
RoutingProtocol::RecvRequest (Ptr<Packet> p, Ipv4Address receiver, Ipv4Address src)
{
  NS_LOG_FUNCTION (this);
  RreqHeader rreqHeader;
  p->RemoveHeader (rreqHeader);

  // A node ignores all RREQs received from any node in its blacklist
  RoutingTableEntry toPrev;
  if (m_routingTable.LookupRoute (src, toPrev))
    {
      if (toPrev.IsUnidirectional ())
        {
          NS_LOG_DEBUG ("Ignoring RREQ from node in blacklist");
          return;
        }
    }

  uint32_t id = rreqHeader.GetId ();
  Ipv4Address origin = rreqHeader.GetOrigin ();

  /*
   *  Node checks to determine whether it has received a RREQ with the same Originator IP Address and RREQ ID.
   *  If such a RREQ has been received, the node silently discards the newly received RREQ.
   */
  if (m_rreqIdCache.IsDuplicate (origin, id))
    {
      NS_LOG_DEBUG ("Ignoring RREQ due to duplicate");
      return;
    }

  // Increment RREQ hop count
  uint8_t hop = rreqHeader.GetHopCount () + 1;
  rreqHeader.SetHopCount (hop);

  /*
   *  When the reverse route is created or updated, the following actions on the route are also carried out:
   *  1. the Originator Sequence Number from the RREQ is compared to the corresponding destination sequence number
   *     in the route table entry and copied if greater than the existing value there
   *  2. the valid sequence number field is set to true;
   *  3. the next hop in the routing table becomes the node from which the  RREQ was received
   *  4. the hop count is copied from the Hop Count in the RREQ message;
   *  5. the Lifetime is set to be the maximum of (ExistingLifetime, MinimalLifetime), where
   *     MinimalLifetime = current time + 2*NetTraversalTime - 2*HopCount*NodeTraversalTime
   */
  RoutingTableEntry toOrigin;
  if (!m_routingTable.LookupRoute (origin, toOrigin))
    {
      Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver));
      RoutingTableEntry newEntry (/*device=*/ dev, /*dst=*/ origin, /*validSeno=*/ true, /*seqNo=*/ rreqHeader.GetOriginSeqno (),
                                              /*iface=*/ m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0), /*hops=*/ hop,
                                              /*nextHop*/ src, /*timeLife=*/ Time ((2 * NetTraversalTime - 2 * hop * NodeTraversalTime)));
      m_routingTable.AddRoute (newEntry);
    }
  else
    {
      if (toOrigin.GetValidSeqNo ())
        {
          if (int32_t (rreqHeader.GetOriginSeqno ()) - int32_t (toOrigin.GetSeqNo ()) > 0)
            toOrigin.SetSeqNo (rreqHeader.GetOriginSeqno ());
        }
      else
        toOrigin.SetSeqNo (rreqHeader.GetOriginSeqno ());
      toOrigin.SetValidSeqNo (true);
      toOrigin.SetNextHop (src);
      toOrigin.SetOutputDevice (m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver)));
      toOrigin.SetInterface (m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0));
      toOrigin.SetHop (hop);
      toOrigin.SetLifeTime (std::max (Time (2 * NetTraversalTime - 2 * hop * NodeTraversalTime),
                                      toOrigin.GetLifeTime ()));
      m_routingTable.Update (toOrigin);
      //m_nb.Update (src, Time (AllowedHelloLoss * HelloInterval));
    }


  RoutingTableEntry toNeighbor;
  if (!m_routingTable.LookupRoute (src, toNeighbor))
    {
      NS_LOG_DEBUG ("Neighbor:" << src << " not found in routing table. Creating an entry"); 
      Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver));
      RoutingTableEntry newEntry (dev, src, false, rreqHeader.GetOriginSeqno (),
                                              m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0),
                                              1, src, ActiveRouteTimeout);
      m_routingTable.AddRoute (newEntry);
    }
  else
    {
      toNeighbor.SetLifeTime (ActiveRouteTimeout);
      toNeighbor.SetValidSeqNo (false);
      toNeighbor.SetSeqNo (rreqHeader.GetOriginSeqno ()); 
      toNeighbor.SetFlag (VALID);
      toNeighbor.SetOutputDevice (m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver)));
      toNeighbor.SetInterface (m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0));
      m_routingTable.Update (toNeighbor);
    }
  m_nb.Update (src, Time (AllowedHelloLoss * HelloInterval));

  NS_LOG_LOGIC (receiver << " receive RREQ with hop count " << static_cast<uint32_t>(rreqHeader.GetHopCount ()) 
                         << " ID " << rreqHeader.GetId ()
                         << " to destination " << rreqHeader.GetDst ());

  //  A node generates a RREP if either:
  //  (i)  it is itself the destination,
  if (IsMyOwnAddress (rreqHeader.GetDst ()))
    {
      m_routingTable.LookupRoute (origin, toOrigin);
      NS_LOG_DEBUG ("Send reply since I am the destination");
      SendReply (rreqHeader, toOrigin);
      return;
    }
  /*
   * (ii) or it has an active route to the destination, the destination sequence number in the node's existing route table entry for the destination
   *      is valid and greater than or equal to the Destination Sequence Number of the RREQ, and the "destination only" flag is NOT set.
   */
  RoutingTableEntry toDst;
  Ipv4Address dst = rreqHeader.GetDst ();
  if (m_routingTable.LookupRoute (dst, toDst))
    {
      /*
       * Drop RREQ, This node RREP wil make a loop.
       */
      if (toDst.GetNextHop () == src)
        {
          NS_LOG_DEBUG ("Drop RREQ from " << src << ", dest next hop " << toDst.GetNextHop ());
          return;
        }
      /*
       * The Destination Sequence number for the requested destination is set to the maximum of the corresponding value
       * received in the RREQ message, and the destination sequence value currently maintained by the node for the requested destination.
       * However, the forwarding node MUST NOT modify its maintained value for the destination sequence number, even if the value
       * received in the incoming RREQ is larger than the value currently maintained by the forwarding node.
       */
      if ((rreqHeader.GetUnknownSeqno () || (int32_t (toDst.GetSeqNo ()) - int32_t (rreqHeader.GetDstSeqno ()) >= 0))
          && toDst.GetValidSeqNo () )
        {
          if (!rreqHeader.GetDestinationOnly () && toDst.GetFlag () == VALID)
            {
              m_routingTable.LookupRoute (origin, toOrigin);
              SendReplyByIntermediateNode (toDst, toOrigin, rreqHeader.GetGratiousRrep ());
              return;
            }
          rreqHeader.SetDstSeqno (toDst.GetSeqNo ());
          rreqHeader.SetUnknownSeqno (false);
        }
    }

  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j =
         m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
    {
      Ptr<Socket> socket = j->first;
      Ipv4InterfaceAddress iface = j->second;
      Ptr<Packet> packet = Create<Packet> ();
      packet->AddHeader (rreqHeader);
      TypeHeader tHeader (AODVTYPE_RREQ);
      packet->AddHeader (tHeader);
      // Send to all-hosts broadcast if on /32 addr, subnet-directed otherwise
      Ipv4Address destination;
      if (iface.GetMask () == Ipv4Mask::GetOnes ())
        {
          destination = Ipv4Address ("255.255.255.255");
        }
      else
        { 
          destination = iface.GetBroadcast ();
        }
      m_lastBcastTime = Simulator::Now ();
      Simulator::Schedule (Time (MilliSeconds (m_uniformRandomVariable->GetInteger (0, 10))), &RoutingProtocol::SendTo, this, socket, packet, destination); 

    }
}

void
RoutingProtocol::SendReply (RreqHeader const & rreqHeader, RoutingTableEntry const & toOrigin)
{
  NS_LOG_FUNCTION (this << toOrigin.GetDestination ());
  /*
   * Destination node MUST increment its own sequence number by one if the sequence number in the RREQ packet is equal to that
   * incremented value. Otherwise, the destination does not change its sequence number before generating the  RREP message.
   */
  if (!rreqHeader.GetUnknownSeqno () && (rreqHeader.GetDstSeqno () == m_seqNo + 1))
    m_seqNo++;
  RrepHeader rrepHeader ( /*prefixSize=*/ 0, /*hops=*/ 0, /*dst=*/ rreqHeader.GetDst (),
                                          /*dstSeqNo=*/ m_seqNo, /*origin=*/ toOrigin.GetDestination (), /*lifeTime=*/ MyRouteTimeout);
  Ptr<Packet> packet = Create<Packet> ();
  packet->AddHeader (rrepHeader);
  TypeHeader tHeader (AODVTYPE_RREP);
  packet->AddHeader (tHeader);
  Ptr<Socket> socket = FindSocketWithInterfaceAddress (toOrigin.GetInterface ());
  NS_ASSERT (socket);
  socket->SendTo (packet, 0, InetSocketAddress (toOrigin.GetNextHop (), AODV_PORT));
}

void
RoutingProtocol::SendReplyByIntermediateNode (RoutingTableEntry & toDst, RoutingTableEntry & toOrigin, bool gratRep)
{
  NS_LOG_FUNCTION (this);
  RrepHeader rrepHeader (/*prefix size=*/ 0, /*hops=*/ toDst.GetHop (), /*dst=*/ toDst.GetDestination (), /*dst seqno=*/ toDst.GetSeqNo (),
                                          /*origin=*/ toOrigin.GetDestination (), /*lifetime=*/ toDst.GetLifeTime ());
  /* If the node we received a RREQ for is a neighbor we are
   * probably facing a unidirectional link... Better request a RREP-ack
   */
  if (toDst.GetHop () == 1)
    {
      rrepHeader.SetAckRequired (true);
      RoutingTableEntry toNextHop;
      m_routingTable.LookupRoute (toOrigin.GetNextHop (), toNextHop);
      toNextHop.m_ackTimer.SetFunction (&RoutingProtocol::AckTimerExpire, this);
      toNextHop.m_ackTimer.SetArguments (toNextHop.GetDestination (), BlackListTimeout);
      toNextHop.m_ackTimer.SetDelay (NextHopWait);
    }
  toDst.InsertPrecursor (toOrigin.GetNextHop ());
  toOrigin.InsertPrecursor (toDst.GetNextHop ());
  m_routingTable.Update (toDst);
  m_routingTable.Update (toOrigin);

  Ptr<Packet> packet = Create<Packet> ();
  packet->AddHeader (rrepHeader);
  TypeHeader tHeader (AODVTYPE_RREP);
  packet->AddHeader (tHeader);
  Ptr<Socket> socket = FindSocketWithInterfaceAddress (toOrigin.GetInterface ());
  NS_ASSERT (socket);
  socket->SendTo (packet, 0, InetSocketAddress (toOrigin.GetNextHop (), AODV_PORT));

  // Generating gratuitous RREPs
  if (gratRep)
    {
      RrepHeader gratRepHeader (/*prefix size=*/ 0, /*hops=*/ toOrigin.GetHop (), /*dst=*/ toOrigin.GetDestination (),
                                                 /*dst seqno=*/ toOrigin.GetSeqNo (), /*origin=*/ toDst.GetDestination (),
                                                 /*lifetime=*/ toOrigin.GetLifeTime ());
      Ptr<Packet> packetToDst = Create<Packet> ();
      packetToDst->AddHeader (gratRepHeader);
      TypeHeader type (AODVTYPE_RREP);
      packetToDst->AddHeader (type);
      Ptr<Socket> socket = FindSocketWithInterfaceAddress (toDst.GetInterface ());
      NS_ASSERT (socket);
      NS_LOG_LOGIC ("Send gratuitous RREP " << packet->GetUid ());
      socket->SendTo (packetToDst, 0, InetSocketAddress (toDst.GetNextHop (), AODV_PORT));
    }
}

void
RoutingProtocol::SendReplyAck (Ipv4Address neighbor)
{
  NS_LOG_FUNCTION (this << " to " << neighbor);
  RrepAckHeader h;
  TypeHeader typeHeader (AODVTYPE_RREP_ACK);
  Ptr<Packet> packet = Create<Packet> ();
  packet->AddHeader (h);
  packet->AddHeader (typeHeader);
  RoutingTableEntry toNeighbor;
  m_routingTable.LookupRoute (neighbor, toNeighbor);
  Ptr<Socket> socket = FindSocketWithInterfaceAddress (toNeighbor.GetInterface ());
  NS_ASSERT (socket);
  socket->SendTo (packet, 0, InetSocketAddress (neighbor, AODV_PORT));
}

void
RoutingProtocol::RecvReply (Ptr<Packet> p, Ipv4Address receiver, Ipv4Address sender)
{
  NS_LOG_FUNCTION (this << " src " << sender);
  RrepHeader rrepHeader;
  p->RemoveHeader (rrepHeader);
  Ipv4Address dst = rrepHeader.GetDst ();
  NS_LOG_LOGIC ("RREP destination " << dst << " RREP origin " << rrepHeader.GetOrigin ());

  uint8_t hop = rrepHeader.GetHopCount () + 1;
  rrepHeader.SetHopCount (hop);

  // If RREP is Hello message
  if (dst == rrepHeader.GetOrigin ())
    {
      ProcessHello (rrepHeader, receiver);
      return;
    }

  /*
   * If the route table entry to the destination is created or updated, then the following actions occur:
   * -  the route is marked as active,
   * -  the destination sequence number is marked as valid,
   * -  the next hop in the route entry is assigned to be the node from which the RREP is received,
   *    which is indicated by the source IP address field in the IP header,
   * -  the hop count is set to the value of the hop count from RREP message + 1
   * -  the expiry time is set to the current time plus the value of the Lifetime in the RREP message,
   * -  and the destination sequence number is the Destination Sequence Number in the RREP message.
   */
  Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver));
  RoutingTableEntry newEntry (/*device=*/ dev, /*dst=*/ dst, /*validSeqNo=*/ true, /*seqno=*/ rrepHeader.GetDstSeqno (),
                                          /*iface=*/ m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0),/*hop=*/ hop,
                                          /*nextHop=*/ sender, /*lifeTime=*/ rrepHeader.GetLifeTime ());
  RoutingTableEntry toDst;
  if (m_routingTable.LookupRoute (dst, toDst))
    {
      /*
       * The existing entry is updated only in the following circumstances:
       * (i) the sequence number in the routing table is marked as invalid in route table entry.
       */
      if (!toDst.GetValidSeqNo ())
        {
          m_routingTable.Update (newEntry);
        }
      // (ii)the Destination Sequence Number in the RREP is greater than the node's copy of the destination sequence number and the known value is valid,
      else if ((int32_t (rrepHeader.GetDstSeqno ()) - int32_t (toDst.GetSeqNo ())) > 0)
        {
          m_routingTable.Update (newEntry);
        }
      else
        {
          // (iii) the sequence numbers are the same, but the route is marked as inactive.
          if ((rrepHeader.GetDstSeqno () == toDst.GetSeqNo ()) && (toDst.GetFlag () != VALID))
            {
              m_routingTable.Update (newEntry);
            }
          // (iv)  the sequence numbers are the same, and the New Hop Count is smaller than the hop count in route table entry.
          else if ((rrepHeader.GetDstSeqno () == toDst.GetSeqNo ()) && (hop < toDst.GetHop ()))
            {
              m_routingTable.Update (newEntry);
            }
        }
    }
  else
    {
      // The forward route for this destination is created if it does not already exist.
      NS_LOG_LOGIC ("add new route");
      m_routingTable.AddRoute (newEntry);
    }
  // Acknowledge receipt of the RREP by sending a RREP-ACK message back
  if (rrepHeader.GetAckRequired ())
    {
      SendReplyAck (sender);
      rrepHeader.SetAckRequired (false);
    }
  NS_LOG_LOGIC ("receiver " << receiver << " origin " << rrepHeader.GetOrigin ());
  if (IsMyOwnAddress (rrepHeader.GetOrigin ()))
    {
      if (toDst.GetFlag () == IN_SEARCH)
        {
          m_routingTable.Update (newEntry);
          m_addressReqTimer[dst].Remove ();
          m_addressReqTimer.erase (dst);
        }
      m_routingTable.LookupRoute (dst, toDst);
      SendPacketFromQueue (dst, toDst.GetRoute ());
      return;
    }

  RoutingTableEntry toOrigin;
  if (!m_routingTable.LookupRoute (rrepHeader.GetOrigin (), toOrigin) || toOrigin.GetFlag () == IN_SEARCH)
    {
      return; // Impossible! drop.
    }
  toOrigin.SetLifeTime (std::max (ActiveRouteTimeout, toOrigin.GetLifeTime ()));
  m_routingTable.Update (toOrigin);

  // Update information about precursors
  if (m_routingTable.LookupValidRoute (rrepHeader.GetDst (), toDst))
    {
      toDst.InsertPrecursor (toOrigin.GetNextHop ());
      m_routingTable.Update (toDst);

      RoutingTableEntry toNextHopToDst;
      m_routingTable.LookupRoute (toDst.GetNextHop (), toNextHopToDst);
      toNextHopToDst.InsertPrecursor (toOrigin.GetNextHop ());
      m_routingTable.Update (toNextHopToDst);

      toOrigin.InsertPrecursor (toDst.GetNextHop ());
      m_routingTable.Update (toOrigin);

      RoutingTableEntry toNextHopToOrigin;
      m_routingTable.LookupRoute (toOrigin.GetNextHop (), toNextHopToOrigin);
      toNextHopToOrigin.InsertPrecursor (toDst.GetNextHop ());
      m_routingTable.Update (toNextHopToOrigin);
    }

  Ptr<Packet> packet = Create<Packet> ();
  packet->AddHeader (rrepHeader);
  TypeHeader tHeader (AODVTYPE_RREP);
  packet->AddHeader (tHeader);
  Ptr<Socket> socket = FindSocketWithInterfaceAddress (toOrigin.GetInterface ());
  NS_ASSERT (socket);
  socket->SendTo (packet, 0, InetSocketAddress (toOrigin.GetNextHop (), AODV_PORT));
}

void
RoutingProtocol::RecvReplyAck (Ipv4Address neighbor)
{
  NS_LOG_FUNCTION (this);
  RoutingTableEntry rt;
  if(m_routingTable.LookupRoute (neighbor, rt))
    {
      rt.m_ackTimer.Cancel ();
      rt.SetFlag (VALID);
      m_routingTable.Update (rt);
    }
}

void
RoutingProtocol::ProcessHello (RrepHeader const & rrepHeader, Ipv4Address receiver )
{
  NS_LOG_FUNCTION (this << "from " << rrepHeader.GetDst ());
  /*
   *  Whenever a node receives a Hello message from a neighbor, the node
   * SHOULD make sure that it has an active route to the neighbor, and
   * create one if necessary.
   */
  RoutingTableEntry toNeighbor;
  if (!m_routingTable.LookupRoute (rrepHeader.GetDst (), toNeighbor))
    {
      Ptr<NetDevice> dev = m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver));
      RoutingTableEntry newEntry (/*device=*/ dev, /*dst=*/ rrepHeader.GetDst (), /*validSeqNo=*/ true, /*seqno=*/ rrepHeader.GetDstSeqno (),
                                              /*iface=*/ m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0),
                                              /*hop=*/ 1, /*nextHop=*/ rrepHeader.GetDst (), /*lifeTime=*/ rrepHeader.GetLifeTime ());
      m_routingTable.AddRoute (newEntry);
    }
  else
    {
      toNeighbor.SetLifeTime (std::max (Time (AllowedHelloLoss * HelloInterval), toNeighbor.GetLifeTime ()));
      toNeighbor.SetSeqNo (rrepHeader.GetDstSeqno ());
      toNeighbor.SetValidSeqNo (true);
      toNeighbor.SetFlag (VALID);
      toNeighbor.SetOutputDevice (m_ipv4->GetNetDevice (m_ipv4->GetInterfaceForAddress (receiver)));
      toNeighbor.SetInterface (m_ipv4->GetAddress (m_ipv4->GetInterfaceForAddress (receiver), 0));
      m_routingTable.Update (toNeighbor);
    }
  if (EnableHello)
    {
      m_nb.Update (rrepHeader.GetDst (), Time (AllowedHelloLoss * HelloInterval));
    }
}

void
RoutingProtocol::RecvError (Ptr<Packet> p, Ipv4Address src )
{
  NS_LOG_FUNCTION (this << " from " << src);
  RerrHeader rerrHeader;
  p->RemoveHeader (rerrHeader);
  std::map<Ipv4Address, uint32_t> dstWithNextHopSrc;
  std::map<Ipv4Address, uint32_t> unreachable;
  m_routingTable.GetListOfDestinationWithNextHop (src, dstWithNextHopSrc);
  std::pair<Ipv4Address, uint32_t> un;
  while (rerrHeader.RemoveUnDestination (un))
    {
      for (std::map<Ipv4Address, uint32_t>::const_iterator i =
           dstWithNextHopSrc.begin (); i != dstWithNextHopSrc.end (); ++i)
      {
        if (i->first == un.first)
          {
            unreachable.insert (un);
          }
      }
    }

  std::vector<Ipv4Address> precursors;
  for (std::map<Ipv4Address, uint32_t>::const_iterator i = unreachable.begin ();
       i != unreachable.end ();)
    {
      if (!rerrHeader.AddUnDestination (i->first, i->second))
        {
          TypeHeader typeHeader (AODVTYPE_RERR);
          Ptr<Packet> packet = Create<Packet> ();
          packet->AddHeader (rerrHeader);
          packet->AddHeader (typeHeader);
          SendRerrMessage (packet, precursors);
          rerrHeader.Clear ();
        }
      else
        {
          RoutingTableEntry toDst;
          m_routingTable.LookupRoute (i->first, toDst);
          toDst.GetPrecursors (precursors);
          ++i;
        }
    }
  if (rerrHeader.GetDestCount () != 0)
    {
      TypeHeader typeHeader (AODVTYPE_RERR);
      Ptr<Packet> packet = Create<Packet> ();
      packet->AddHeader (rerrHeader);
      packet->AddHeader (typeHeader);
      SendRerrMessage (packet, precursors);
    }
  m_routingTable.InvalidateRoutesWithDst (unreachable);
}

void
RoutingProtocol::RouteRequestTimerExpire (Ipv4Address dst)
{
  NS_LOG_LOGIC (this);
  RoutingTableEntry toDst;
  if (m_routingTable.LookupValidRoute (dst, toDst))
    {
      SendPacketFromQueue (dst, toDst.GetRoute ());
      NS_LOG_LOGIC ("route to " << dst << " found");
      return;
    }
  /*
   *  If a route discovery has been attempted RreqRetries times at the maximum TTL without
   *  receiving any RREP, all data packets destined for the corresponding destination SHOULD be
   *  dropped from the buffer and a Destination Unreachable message SHOULD be delivered to the application.
   */
  if (toDst.GetRreqCnt () == RreqRetries)
    {
      NS_LOG_LOGIC ("route discovery to " << dst << " has been attempted RreqRetries (" << RreqRetries << ") times");
      m_addressReqTimer.erase (dst);
      m_routingTable.DeleteRoute (dst);
      NS_LOG_DEBUG ("Route not found. Drop all packets with dst " << dst);
      m_queue.DropPacketWithDst (dst);
      return;
    }

  if (toDst.GetFlag () == IN_SEARCH)
    {
      NS_LOG_LOGIC ("Resend RREQ to " << dst << " ttl " << NetDiameter);
      SendRequest (dst);
    }
  else
    {
      NS_LOG_DEBUG ("Route down. Stop search. Drop packet with destination " << dst);
      m_addressReqTimer.erase (dst);
      m_routingTable.DeleteRoute (dst);
      m_queue.DropPacketWithDst (dst);
    }
}

void
RoutingProtocol::HelloTimerExpire ()
{
  NS_LOG_FUNCTION (this);
  Time offset = Time (Seconds (0));
  if (m_lastBcastTime > Time (Seconds (0)))
    {
      offset = Simulator::Now () - m_lastBcastTime;
      NS_LOG_DEBUG ("Hello deferred due to last bcast at:" << m_lastBcastTime);
    }
  else
    {
      SendHello ();
    }
  m_htimer.Cancel ();
  Time diff = HelloInterval - offset;
  m_htimer.Schedule (std::max (Time (Seconds (0)), diff));
  m_lastBcastTime = Time (Seconds (0));
}

void
RoutingProtocol::RreqRateLimitTimerExpire ()
{
  NS_LOG_FUNCTION (this);
  m_rreqCount = 0;
  m_rreqRateLimitTimer.Schedule (Seconds (1));
}

void
RoutingProtocol::RerrRateLimitTimerExpire ()
{
  NS_LOG_FUNCTION (this);
  m_rerrCount = 0;
  m_rerrRateLimitTimer.Schedule (Seconds (1));
}

void
RoutingProtocol::AckTimerExpire (Ipv4Address neighbor, Time blacklistTimeout)
{
  NS_LOG_FUNCTION (this);
  m_routingTable.MarkLinkAsUnidirectional (neighbor, blacklistTimeout);
}

void
RoutingProtocol::SendHello ()
{
  NS_LOG_FUNCTION (this);
  /* Broadcast a RREP with TTL = 1 with the RREP message fields set as follows:
   *   Destination IP Address         The node's IP address.
   *   Destination Sequence Number    The node's latest sequence number.
   *   Hop Count                      0
   *   Lifetime                       AllowedHelloLoss * HelloInterval
   */
  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j = m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
    {
      Ptr<Socket> socket = j->first;
      Ipv4InterfaceAddress iface = j->second;
      RrepHeader helloHeader (/*prefix size=*/ 0, /*hops=*/ 0, /*dst=*/ iface.GetLocal (), /*dst seqno=*/ m_seqNo,
                                               /*origin=*/ iface.GetLocal (),/*lifetime=*/ Time (AllowedHelloLoss * HelloInterval));
      Ptr<Packet> packet = Create<Packet> ();
      packet->AddHeader (helloHeader);
      TypeHeader tHeader (AODVTYPE_RREP);
      packet->AddHeader (tHeader);
      // Send to all-hosts broadcast if on /32 addr, subnet-directed otherwise
      Ipv4Address destination;
      if (iface.GetMask () == Ipv4Mask::GetOnes ())
        {
          destination = Ipv4Address ("255.255.255.255");
        }
      else
        { 
          destination = iface.GetBroadcast ();
        }
      Time jitter = Time (MilliSeconds (m_uniformRandomVariable->GetInteger (0, 10)));
      Simulator::Schedule (jitter, &RoutingProtocol::SendTo, this , socket, packet, destination);
    }
}

void
RoutingProtocol::SendPacketFromQueue (Ipv4Address dst, Ptr<Ipv4Route> route)
{
  NS_LOG_FUNCTION (this);
  QueueEntry queueEntry;
  while (m_queue.Dequeue (dst, queueEntry))
    {
      DeferredRouteOutputTag tag;
      Ptr<Packet> p = ConstCast<Packet> (queueEntry.GetPacket ());
      if (p->RemovePacketTag (tag) && 
          tag.GetInterface() != -1 &&
          tag.GetInterface() != m_ipv4->GetInterfaceForDevice (route->GetOutputDevice ()))
        {
          NS_LOG_DEBUG ("Output device doesn't match. Dropped.");
          return;
        }
      UnicastForwardCallback ucb = queueEntry.GetUnicastForwardCallback ();
      Ipv4Header header = queueEntry.GetIpv4Header ();
      header.SetSource (route->GetSource ());
      header.SetTtl (header.GetTtl () + 1); // compensate extra TTL decrement by fake loopback routing
      ucb (route, p, header);
    }
}

void
RoutingProtocol::SendRerrWhenBreaksLinkToNextHop (Ipv4Address nextHop)
{
  NS_LOG_FUNCTION (this << nextHop);
  RerrHeader rerrHeader;
  std::vector<Ipv4Address> precursors;
  std::map<Ipv4Address, uint32_t> unreachable;

  RoutingTableEntry toNextHop;
  if (!m_routingTable.LookupRoute (nextHop, toNextHop))
    return;
  toNextHop.GetPrecursors (precursors);
  rerrHeader.AddUnDestination (nextHop, toNextHop.GetSeqNo ());
  m_routingTable.GetListOfDestinationWithNextHop (nextHop, unreachable);
  for (std::map<Ipv4Address, uint32_t>::const_iterator i = unreachable.begin (); i
       != unreachable.end ();)
    {
      if (!rerrHeader.AddUnDestination (i->first, i->second))
        {
          NS_LOG_LOGIC ("Send RERR message with maximum size.");
          TypeHeader typeHeader (AODVTYPE_RERR);
          Ptr<Packet> packet = Create<Packet> ();
          packet->AddHeader (rerrHeader);
          packet->AddHeader (typeHeader);
          SendRerrMessage (packet, precursors);
          rerrHeader.Clear ();
        }
      else
        {
          RoutingTableEntry toDst;
          m_routingTable.LookupRoute (i->first, toDst);
          toDst.GetPrecursors (precursors);
          ++i;
        }
    }
  if (rerrHeader.GetDestCount () != 0)
    {
      TypeHeader typeHeader (AODVTYPE_RERR);
      Ptr<Packet> packet = Create<Packet> ();
      packet->AddHeader (rerrHeader);
      packet->AddHeader (typeHeader);
      SendRerrMessage (packet, precursors);
    }
  unreachable.insert (std::make_pair (nextHop, toNextHop.GetSeqNo ()));
  m_routingTable.InvalidateRoutesWithDst (unreachable);
}

void
RoutingProtocol::SendRerrWhenNoRouteToForward (Ipv4Address dst,
                                               uint32_t dstSeqNo, Ipv4Address origin)
{
  NS_LOG_FUNCTION (this);
  // A node SHOULD NOT originate more than RERR_RATELIMIT RERR messages per second.
  if (m_rerrCount == RerrRateLimit)
    {
      // Just make sure that the RerrRateLimit timer is running and will expire
      NS_ASSERT (m_rerrRateLimitTimer.IsRunning ());
      // discard the packet and return
      NS_LOG_LOGIC ("RerrRateLimit reached at " << Simulator::Now ().GetSeconds () << " with timer delay left " 
                                                << m_rerrRateLimitTimer.GetDelayLeft ().GetSeconds ()
                                                << "; suppressing RERR");
      return;
    }
  RerrHeader rerrHeader;
  rerrHeader.AddUnDestination (dst, dstSeqNo);
  RoutingTableEntry toOrigin;
  Ptr<Packet> packet = Create<Packet> ();
  packet->AddHeader (rerrHeader);
  packet->AddHeader (TypeHeader (AODVTYPE_RERR));
  if (m_routingTable.LookupValidRoute (origin, toOrigin))
    {
      Ptr<Socket> socket = FindSocketWithInterfaceAddress (
          toOrigin.GetInterface ());
      NS_ASSERT (socket);
      NS_LOG_LOGIC ("Unicast RERR to the source of the data transmission");
      socket->SendTo (packet, 0, InetSocketAddress (toOrigin.GetNextHop (), AODV_PORT));
    }
  else
    {
      for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator i =
             m_socketAddresses.begin (); i != m_socketAddresses.end (); ++i)
        {
          Ptr<Socket> socket = i->first;
          Ipv4InterfaceAddress iface = i->second;
          NS_ASSERT (socket);
          NS_LOG_LOGIC ("Broadcast RERR message from interface " << iface.GetLocal ());
          // Send to all-hosts broadcast if on /32 addr, subnet-directed otherwise
          Ipv4Address destination;
          if (iface.GetMask () == Ipv4Mask::GetOnes ())
            {
              destination = Ipv4Address ("255.255.255.255");
            }
          else
            { 
              destination = iface.GetBroadcast ();
            }
          socket->SendTo (packet, 0, InetSocketAddress (destination, AODV_PORT));
        }
    }
}

void
RoutingProtocol::SendRerrMessage (Ptr<Packet> packet, std::vector<Ipv4Address> precursors)
{
  NS_LOG_FUNCTION (this);

  if (precursors.empty ())
    {
      NS_LOG_LOGIC ("No precursors");
      return;
    }
  // A node SHOULD NOT originate more than RERR_RATELIMIT RERR messages per second.
  if (m_rerrCount == RerrRateLimit)
    {
      // Just make sure that the RerrRateLimit timer is running and will expire
      NS_ASSERT (m_rerrRateLimitTimer.IsRunning ());
      // discard the packet and return
      NS_LOG_LOGIC ("RerrRateLimit reached at " << Simulator::Now ().GetSeconds () << " with timer delay left " 
                                                << m_rerrRateLimitTimer.GetDelayLeft ().GetSeconds ()
                                                << "; suppressing RERR");
      return;
    }
  // If there is only one precursor, RERR SHOULD be unicast toward that precursor
  if (precursors.size () == 1)
    {
      RoutingTableEntry toPrecursor;
      if (m_routingTable.LookupValidRoute (precursors.front (), toPrecursor))
        {
          Ptr<Socket> socket = FindSocketWithInterfaceAddress (toPrecursor.GetInterface ());
          NS_ASSERT (socket);
          NS_LOG_LOGIC ("one precursor => unicast RERR to " << toPrecursor.GetDestination () << " from " << toPrecursor.GetInterface ().GetLocal ());
          Simulator::Schedule (Time (MilliSeconds (m_uniformRandomVariable->GetInteger (0, 10))), &RoutingProtocol::SendTo, this, socket, packet, precursors.front ());
          m_rerrCount++;
        }
      return;
    }

  //  Should only transmit RERR on those interfaces which have precursor nodes for the broken route
  std::vector<Ipv4InterfaceAddress> ifaces;
  RoutingTableEntry toPrecursor;
  for (std::vector<Ipv4Address>::const_iterator i = precursors.begin (); i != precursors.end (); ++i)
    {
      if (m_routingTable.LookupValidRoute (*i, toPrecursor) && 
          std::find (ifaces.begin (), ifaces.end (), toPrecursor.GetInterface ()) == ifaces.end ())
        {
          ifaces.push_back (toPrecursor.GetInterface ());
        }
    }

  for (std::vector<Ipv4InterfaceAddress>::const_iterator i = ifaces.begin (); i != ifaces.end (); ++i)
    {
      Ptr<Socket> socket = FindSocketWithInterfaceAddress (*i);
      NS_ASSERT (socket);
      NS_LOG_LOGIC ("Broadcast RERR message from interface " << i->GetLocal ());
      // Send to all-hosts broadcast if on /32 addr, subnet-directed otherwise
      Ipv4Address destination;
      if (i->GetMask () == Ipv4Mask::GetOnes ())
        {
          destination = Ipv4Address ("255.255.255.255");
        }
      else
        { 
          destination = i->GetBroadcast ();
        }
      Simulator::Schedule (Time (MilliSeconds (m_uniformRandomVariable->GetInteger (0, 10))), &RoutingProtocol::SendTo, this, socket, packet, destination);
    }
}

Ptr<Socket>
RoutingProtocol::FindSocketWithInterfaceAddress (Ipv4InterfaceAddress addr ) const
{
  NS_LOG_FUNCTION (this << addr);
  for (std::map<Ptr<Socket>, Ipv4InterfaceAddress>::const_iterator j =
         m_socketAddresses.begin (); j != m_socketAddresses.end (); ++j)
    {
      Ptr<Socket> socket = j->first;
      Ipv4InterfaceAddress iface = j->second;
      if (iface == addr)
        return socket;
    }
  Ptr<Socket> socket;
  return socket;
}

}
}