/// <summary>
/// Handles an incoming HELLO packet.
/// </summary>
/// <param name="incomingPacket"></param>
private void HandleHello(Message incomingPacket)
{
var hello = (Hello)incomingPacket.Payload;
var route = new AodvTableEntry
{
Valid = true,
DestinationAddress = hello.DestinationAddress,
DestinationSequenceNumber = hello.DestinationSequenceNumber,
HopCount = 1,
NextHop = incomingPacket.PreviousHop,
ValidDestinationSequenceNumberFlag = true,
ExpirationTime = new DateTime(hello.Lifetime.Ticks) //Creates an exact copy of the lifetime in DateTime format.
};
//Ensure that we have an active route towards the neighbour
if (!_aodvHelper.RoutingTable.RouteExists(hello.DestinationAddress))
{
_aodvHelper.RoutingTable.AddEntry(route);
}
else //Route does exist, update what we can infer from the fact that our neighbour send us a HELLO
{
_aodvHelper.RoutingTable.UpdateEntry(route);
}
_logger.WriteLine("Processed HELLO from " + hello.DestinationAddress);
}
/// <summary>
/// Prints the creation or update of a routing entry to the log file.
/// </summary>
/// <param name="entry"></param>
/// <param name="update"></param>
private void LogRouteEntry(AodvTableEntry entry, bool update)
{
var added = update ? "Routing entry updated: " : "Routing entry added: ";
var msg = "Destination: " + entry.DestinationAddress +
", DSN: " + entry.DestinationSequenceNumber +
", Valid DSN: " + entry.ValidDestinationSequenceNumberFlag +
", Hop Count: " + entry.HopCount +
", Next Hop: " + entry.NextHop +
", Valid: " + entry.Valid +
", ExpirationTime: " + entry.ExpirationTime.ToLongTimeString();
_logger.WriteLine(added + msg);
}
/// <summary>
/// Updates an existing routing table entry, with the entry provided.
/// </summary>
/// <param name="entry"></param>
public void UpdateEntry(AodvTableEntry entry)
{
var destination = entry.DestinationAddress;
_table[destination].DestinationAddress = entry.DestinationAddress;
_table[destination].DestinationSequenceNumber = entry.DestinationSequenceNumber;
_table[destination].ValidDestinationSequenceNumberFlag = entry.ValidDestinationSequenceNumberFlag;
_table[destination].HopCount = entry.HopCount;
_table[destination].Valid = entry.Valid;
_table[destination].NextHop = entry.NextHop;
_table[destination].Precursors = entry.Precursors.ToList();
_table[destination].ExpirationTime = entry.ExpirationTime;
LogRouteEntry(entry, true);
}
/// <summary>
/// Handles an incoming RREP packet.
/// </summary>
/// <param name="incomingPacket"></param>
private void HandleRrep(Message incomingPacket)
{
var rrep = (Rrep)incomingPacket.Payload;
//var outgoingMessages = new Dictionary<string, Message>();
//Search routing table for route to previous hop (where RREP was received from), and create it, if it does not exists (may now be used for forwarding)
if (!_aodvHelper.RoutingTable.RouteExists(incomingPacket.PreviousHop))
{
var route = new AodvTableEntry
{
Valid = true,
DestinationAddress = incomingPacket.PreviousHop,
DestinationSequenceNumber = 0,
HopCount = 1,
NextHop = incomingPacket.PreviousHop,
ValidDestinationSequenceNumberFlag = false,
ExpirationTime = _time.GetFutureTime(_aodvParameters.ActiveRouteTimeout),
Precursors = new List <string> {
_aodvHelper.RoutingTable.GetEntry(rrep.OriginatorAddress)?.NextHop
}
};
_logger.WriteLine("1Adding route entry from received RREP towards previous hop: " + incomingPacket.PreviousHop);
_aodvHelper.RoutingTable.AddEntry(route);
}
else //Route does exist, update what we can infer from the fact that our neighbour forwarded a RREQ to us
{
var route = _aodvHelper.RoutingTable.GetEntry(incomingPacket.PreviousHop);
route.Valid = true;
route.HopCount = 1;
route.NextHop = incomingPacket.PreviousHop;
route.ExpirationTime = _time.GetFutureTime(_aodvParameters.ActiveRouteTimeout);
_logger.WriteLine("2Updating existing route entry for previous hop from received RREP: " + incomingPacket.PreviousHop);
_aodvHelper.RoutingTable.UpdateEntry(route);
}
//Increment HopCount, since me receiving the RREP, adds another hop to the path
rrep.HopCount = rrep.HopCount + 1;
//If route forward in RREP path (towards destination in RREP) does not exist, create it
if (!_aodvHelper.RoutingTable.RouteExists(rrep.DestinationAddress))
{
var destinationRoute = new AodvTableEntry
{
Valid = true,
DestinationAddress = rrep.DestinationAddress,
DestinationSequenceNumber = rrep.DestinationSequenceNumber,
HopCount = rrep.HopCount,
ValidDestinationSequenceNumberFlag = true,
NextHop = incomingPacket.PreviousHop,
ExpirationTime = rrep.Lifetime,
Precursors = new List <string>() //Precursor added below, per section 6.7 last paragraph
};
_logger.WriteLine("Creating route entry for destination from received RREP: " + rrep.DestinationAddress);
_aodvHelper.RoutingTable.AddEntry(destinationRoute); //If I'm the originator in the RREP, I now have a route to the destination, yay!
}
else //Route towards destination in rrep exists
{
var entry = _aodvHelper.RoutingTable.GetEntry(rrep.DestinationAddress);
var identicalDsn = rrep.DestinationSequenceNumber == entry.DestinationSequenceNumber;
var update = false;
if (!entry.ValidDestinationSequenceNumberFlag) // Section 6.7 (i)
{
update = true;
}
else if (rrep.DestinationSequenceNumber > entry.DestinationSequenceNumber && entry.ValidDestinationSequenceNumberFlag) //Section 6.7 (ii)
{
update = true;
}
else if (identicalDsn && !entry.Valid) // Section 6.7 (iii)
{
update = true;
}
else if (identicalDsn && rrep.HopCount < entry.HopCount) //Section 6.7 (iv)
{
update = true;
}
if (update)
{
entry.Valid = true;
entry.ValidDestinationSequenceNumberFlag = true;
entry.NextHop = incomingPacket.PreviousHop;
entry.HopCount = rrep.HopCount;
entry.ExpirationTime = rrep.Lifetime; //Current time + rrep.lifetime
entry.DestinationSequenceNumber = rrep.DestinationSequenceNumber;
//Precursor added below, per section 6.7 last paragraph
_logger.WriteLine("3Updating existing route entry for destination from received RREP: " + rrep.DestinationAddress);
_aodvHelper.RoutingTable.UpdateEntry(entry);
}
}
//Removes all buffered RREQs I have sent for this destination
_aodvHelper.RemoveLocalBufferedRreq(rrep.DestinationAddress);
//If I'm not the originator (i.e. I am not the one who requested the route)
if (rrep.OriginatorAddress != _localAddress)
{
//Verify that I have a route to the destination. Previous-hop has a routing entry that says I do, otherwise he wouldnt have forwarded the RREP to me.
if (!_aodvHelper.RoutingTable.ActiveRouteExists(rrep.OriginatorAddress))
{
_statistics.AodvDropped_NoActiveForwardingRoute(incomingPacket);
//Well, I dont have a route (even though I should - most likely due to a rrep sent back too late)
//Send RERR to previous hop
var ud = new List <UnreachableDestination> {
new UnreachableDestination(rrep.OriginatorAddress, 0)
};
var rerrMsg = new Message(new Rerr(ud), incomingPacket.PreviousHop, _localAddress, _conf.MessageTtlValue);
SendAodvMessage(rerrMsg, incomingPacket.PreviousHop);
return;
}
//Add next hop towards originator, to precursors of destination (6.7, last paragraph)
//Section 6.7, last paragraph
//"When any node transmits a RREP, the precursor list for the corresponding DESTINATION node is updated, by adding to it, the next hop node
//to which the RREP is forwarded." So, "the next hop node to which the RREP is forwarded" is next hop towards ORIGINATOR.
_aodvHelper.RoutingTable.AddPrecursorToEntry(rrep.DestinationAddress, _aodvHelper.RoutingTable.GetEntry(rrep.OriginatorAddress).NextHop);
//Update lifetime of reverse route towards originator
var reverseRoute = _aodvHelper.RoutingTable.GetEntry(rrep.OriginatorAddress);
var future = _time.GetFutureTime(_aodvParameters.ActiveRouteTimeout);
reverseRoute.ExpirationTime = reverseRoute.ExpirationTime > future ? reverseRoute.ExpirationTime : future;
//Forward RREP to node according to routing table towards the originator
var outMsg = new Message(incomingPacket);
outMsg.Payload = new Rrep(rrep);
SendAodvMessage(outMsg, reverseRoute.NextHop);
_logger.WriteLine("4Updating existing route entry for originator from received RREP: " + rrep.OriginatorAddress);
_aodvHelper.RoutingTable.UpdateEntry(reverseRoute);
}
}
/// <summary>
/// Handles an incoming RREQ packet.
/// </summary>
/// <param name="incomingPacket"></param>
private void HandleRreq(Message incomingPacket)
{
//Processing RREQ according to section 6.5
var rreq = (Rreq)incomingPacket.Payload; //Cast message to right type
//Check that received RREQ has not been received and processed before
if (_aodvHelper.RreqAttemptExist(rreq.DestinationAddress, rreq.OriginatorAddress))
{
_logger.WriteLine("Incoming RREQ from " + rreq.OriginatorAddress + " discarded, since it has been processed before.");
return; //Discard RREQ
}
//RREQ not received before, place in buffer with 0 as attempt number
_aodvHelper.AddBufferedRreqAttempt(new BufferedRreqAttempt(0, rreq, _conf.AodvConfiguration.PathDiscoveryTime));
//First, create/update route to previous hop. If route to previous hop exists, update lifetime
if (_aodvHelper.RoutingTable.ActiveRouteExists(incomingPacket.PreviousHop))
{
var prevRoute = _aodvHelper.RoutingTable.GetEntry(incomingPacket.PreviousHop);
prevRoute.Valid = true;
prevRoute.HopCount = 1;
prevRoute.NextHop = incomingPacket.PreviousHop;
prevRoute.ExpirationTime = _time.GetFutureTime(_aodvParameters.ActiveRouteTimeout);
_logger.WriteLine("RREQ handler: Updating route to previous hop: " + incomingPacket.PreviousHop + " for RREQ #" + rreq.RouteRequestId);
_aodvHelper.RoutingTable.UpdateEntry(prevRoute);
}
else //Route did not exist, so create it
{
var prevHopEntry = new AodvTableEntry
{
Valid = true,
DestinationAddress = incomingPacket.PreviousHop,
DestinationSequenceNumber = 0,
ValidDestinationSequenceNumberFlag = false, //(He's my neighbour, so even though I dont know his sequence number, I know that he's there)
HopCount = 1, //Only 1 hop to previous neighbour (duh)
NextHop = incomingPacket.PreviousHop,
ExpirationTime = _time.GetFutureTime(_aodvParameters.ActiveRouteTimeout)
};
_logger.WriteLine("RREQ handler: Adding route to previous hop: " + incomingPacket.PreviousHop + " for RREQ #" + rreq.RouteRequestId);
_aodvHelper.RoutingTable.AddEntry(prevHopEntry);
}
//RREQ has not been seen before or was not sent by me, continue to process it.
rreq.HopCount = rreq.HopCount + 1; //Increment HopCount in RREQ, since me receiving it, was one hop more
//Create or update reverse route to RREQ Originator
var oldEntry = _aodvHelper.RoutingTable.GetEntry(rreq.OriginatorAddress);
var minimalLifetime = _aodvParameters.MinimalLifetime(rreq.HopCount);
//No route to originator exists, create it
if (oldEntry == null)
{
var originatorRoute = new AodvTableEntry
{
DestinationAddress = rreq.OriginatorAddress,
DestinationSequenceNumber = rreq.OriginatorSequenceNumber,
ValidDestinationSequenceNumberFlag = true,
HopCount = rreq.HopCount,
Valid = true,
NextHop = incomingPacket.PreviousHop,
ExpirationTime = minimalLifetime
};
_logger.WriteLine("RREQ handler: Adding route to originator: " + rreq.OriginatorAddress + " for RREQ #" + rreq.RouteRequestId);
_aodvHelper.RoutingTable.AddEntry(originatorRoute);
}
else //Route exists, update existing entry
{
var originatorRoute = new AodvTableEntry
{
DestinationAddress = rreq.OriginatorAddress,
DestinationSequenceNumber = rreq.OriginatorSequenceNumber > oldEntry.DestinationSequenceNumber ? rreq.OriginatorSequenceNumber : oldEntry.DestinationSequenceNumber, //See section 6.5, action 1.
ValidDestinationSequenceNumberFlag = true,
HopCount = rreq.HopCount,
Valid = true,
NextHop = incomingPacket.PreviousHop,
ExpirationTime = oldEntry.ExpirationTime > minimalLifetime ? oldEntry.ExpirationTime : minimalLifetime
};
_logger.WriteLine("RREQ handler: Updating route to originator: " + rreq.OriginatorAddress + " for RREQ #" + rreq.RouteRequestId);
_aodvHelper.RoutingTable.UpdateEntry(originatorRoute); //And now we have a route towards the originator that can be used. neat-o.
}
//If I am the destination specified in RREQ
if (rreq.DestinationAddress == _localAddress) //Section 6.6 (i) and section 6.6.1
{
//Increment my sequence number, if DSN in RREQ is 1 larger per secton 6.6.1
if (rreq.DestinationSequenceNumber == _aodvHelper.RoutingTable.SequenceNumber + 1)
{
_aodvHelper.RoutingTable.IncrementSequenceNumber();
}
var rrep = new Rrep
{
OriginatorAddress = rreq.OriginatorAddress,
DestinationAddress = rreq.DestinationAddress,
DestinationSequenceNumber = _aodvHelper.RoutingTable.SequenceNumber,
HopCount = 0,
Lifetime = _time.GetFutureTime(_aodvParameters.MyRouteTimeout) //Section 6.6.1, see also section 10.
};
var responseMsg = new Message(rrep, rreq.OriginatorAddress, _localAddress, _conf.MessageTtlValue);
SendAodvMessage(responseMsg, incomingPacket.PreviousHop); //Send RREP to previous hop, which is where I received the RREQ from
}
//If I have an active route to destination, which upholds requirements in section 6.6 (ii), see section 6.6.2
else if (_aodvHelper.RoutingTable.ActiveRouteExists(rreq.DestinationAddress) && //If I have an active route
_aodvHelper.RoutingTable.GetEntry(rreq.DestinationAddress).ValidDestinationSequenceNumberFlag && //and the route has a valid dsn
_aodvHelper.RoutingTable.GetEntry(rreq.DestinationAddress).DestinationSequenceNumber >= rreq.DestinationSequenceNumber && //and route dsn is >= rreq.dsn
!rreq.D) //and rreq must NOT only be answered by destination
{
var forwardRoute = _aodvHelper.RoutingTable.GetEntry(rreq.DestinationAddress);
var rrep = new Rrep
{
OriginatorAddress = rreq.OriginatorAddress,
DestinationAddress = rreq.DestinationAddress,
DestinationSequenceNumber = forwardRoute.DestinationSequenceNumber,
HopCount = forwardRoute.HopCount,
Lifetime = _time.GetFutureTime((forwardRoute.ExpirationTime - _time.CurrentTime).TotalSeconds) //6.6.2, "subtract current time from expiration time in route table entry"
};
//Add previous hop of incoming message to precursor list of destination
_aodvHelper.RoutingTable.AddPrecursorToEntry(rreq.DestinationAddress, incomingPacket.PreviousHop);
//Add next-hop of forward route to precursor list of originator
_aodvHelper.RoutingTable.AddPrecursorToEntry(rreq.OriginatorAddress, forwardRoute.NextHop);
//Place RREP in outbox
var responseMsg = new Message(rrep, rreq.OriginatorAddress, _localAddress, _conf.MessageTtlValue);
SendAodvMessage(responseMsg, incomingPacket.PreviousHop); //Send RREP to previous hop, which is where I received the RREQ from
//Send gratuitous RREP if required in RREQ, specified in section 6.6.3. Dont send it, if path to destination goes through previousHop
if (rreq.G)
{
var gratuitousRrep = new Rrep
{
HopCount = _aodvHelper.RoutingTable.GetEntry(rreq.OriginatorAddress).HopCount,
DestinationAddress = rreq.OriginatorAddress,
DestinationSequenceNumber = rreq.OriginatorSequenceNumber,
OriginatorAddress = rreq.DestinationAddress,
Lifetime = _time.GetFutureTime((_aodvHelper.RoutingTable.GetEntry(rreq.OriginatorAddress).ExpirationTime - _time.CurrentTime).TotalSeconds) //"Remaining lifetime of route towards RREQ originator, as known by intermediate node" (expiration time - current time = remaining time)
};
var gratuitousMsg = new Message(gratuitousRrep, rreq.DestinationAddress, _localAddress, _conf.MessageTtlValue);
SendAodvMessage(gratuitousMsg, forwardRoute.NextHop); //Gratuitous RREP sent forward
}
}
//Else, I have no active route and am not the destination
else
{
var outMsg = new Message(incomingPacket);
rreq.DestinationSequenceNumber = Math.Max(rreq.DestinationSequenceNumber, _aodvHelper.RoutingTable.GetEntry(rreq.DestinationAddress)?.DestinationSequenceNumber ?? -1); //Set DSN to max of rreq.dsn or table[destination].dsn
outMsg.Payload = new Rreq(rreq);
outMsg.DestinationAddress = SimulationConstants.BroadcastAddress;
SendAodvMessage(outMsg, SimulationConstants.BroadcastAddress);
}
}
/// <summary>
/// Adds a new routing table entry to the routing table
/// </summary>
/// <param name="entry"></param>
public void AddEntry(AodvTableEntry entry)
{
_table[entry.DestinationAddress] = entry;
LogRouteEntry(entry, false);
}
