/// <summary>
/// Handles an incoming RERR packet.
/// </summary>
/// <param name="incomingPacket"></param>
private void HandleRerr(Message incomingPacket)
{
//Section 6.11 (iii)
var rerr = (Rerr)incomingPacket.Payload;
var unreachableDestinations = new List <UnreachableDestination>();
//For each of the received unreachable destinations
foreach (var unreachableDestination in rerr.UnreachableDestinations)
{
var invalidRoute = _aodvHelper.RoutingTable.GetEntry(unreachableDestination.UnreachableDestinationAddress);
//If I have an active route to that destination, and the route uses the transmitter of the RREP as the next-hop (then route is also invalid for me)
if (invalidRoute != null && invalidRoute.Valid && invalidRoute.NextHop == incomingPacket.PreviousHop)
{
//Create a list of destinations from the RERR, for which i have a routing entry, that uses the rerr.previoushop as next hop.
var ud = new UnreachableDestination(invalidRoute.DestinationAddress, invalidRoute.DestinationSequenceNumber);
unreachableDestinations.Add(ud);
//Perform invalidation actions from RFC
_aodvHelper.RoutingTable.UpdateDestinationSequenceNumber(invalidRoute.DestinationAddress, unreachableDestination.UnreachableDestinationSequenceNumber); //Section 6.11 (iii)
_aodvHelper.RoutingTable.InvalidateEntry(invalidRoute.DestinationAddress);
}
}
//Find route with largest number of precursors
var minCount = 0;
var precursors = new List <string>();
foreach (var ud in unreachableDestinations)
{
var route = _aodvHelper.RoutingTable.GetEntry(ud.UnreachableDestinationAddress);
var precursorCount = route.Precursors.Count;
if (precursorCount > minCount)
{
minCount = precursorCount;
precursors = route.Precursors;
}
}
if (precursors.Count > 0)
{
var msg = new Message(new Rerr(rerr), precursors[0], _localAddress, _conf.MessageTtlValue);
SendAodvMessage(msg, precursors[0]);
}
}
/// <summary>
/// Called when an RERR is to be sent. It invalidates any routing entries that have broken as a result of the missing neighbour,
/// and returns a list of destinations now unreachable.
/// </summary>
/// <param name="missingNextHop"></param>
/// <returns>List of destinations that are now unreachable due to the missing next hop</returns>
public List <UnreachableDestination> HandleAndGetUnreachableDestinations(string missingNextHop)
{
var unreachableDestinations = new List <UnreachableDestination>();
//Per section 6.11 (i) and (ii)
foreach (var destination in _table.Keys)
{
//If this is an entry for a now unreachable destination or the missing neighbour
if (_table[destination].NextHop == missingNextHop)
{
var ud = new UnreachableDestination(destination, _table[destination].DestinationSequenceNumber);
unreachableDestinations.Add(ud);
if (_table[destination].Valid)
{
_table[destination].DestinationSequenceNumber++;
}
_table[destination].Invalidate(_conf);
}
}
return(unreachableDestinations);
}
