private void SendRoutingMessage(Message.RoutingMessage rm)
{
Frame frame = Frame.GetFrame(_macHeader + Message.RoutingMessage.cLength + _macTailer);
if (frame == null)
return;
frame.ReserveHeader(_macHeader);
if (!rm.WriteToFrame(frame))
{
Frame.Release(ref frame);
return;
}
bool ok;
UInt16 nextHop;
if (rm.IsRequest)
{
ok = true;
nextHop = cBroadcastShortAddr;
}
else
{
ok = _routingTable.GetRoute(rm.TargetAddr, out nextHop);
}
if (ok)
{
Trace.Print("Sending " + rm.ToString());
MacDataRequest(nextHop, ref frame);
}
Frame.Release(ref frame);
}
private void SendRouteRequest(UInt16 tgtAddrShort)
{
Message.RoutingMessage rm = new Message.RoutingMessage();
rm.IsRequest = true;
rm.HopsLeft = cDefaultHopLimit;
rm.HopCount = 0; // counter from originator, initially set to zero
rm.MinLQI = 0xFF; // initial value
rm.SeqNo = IncSeqNoDYMO();
rm.TargetAddr = tgtAddrShort;
rm.OriginatorAddr = _addrShort;
SendRoutingMessage(rm);
}
private void HandleRoutingMessage(
MacAddress srcAddr,
MacAddress dstAddr,
ref Frame sdu,
byte lqi)
{
Message.RoutingMessage rm = new Message.RoutingMessage();
if (srcAddr.Mode == MacAddressingMode.ShortAddress && rm.ReadFromFrame(sdu))
{
Trace.Print("Received: " + rm.ToString());
rm.HopCount++;
_neighbourTable.UpdateLqi(srcAddr.ShortAddress, lqi);
if (rm.OriginatorAddr == _addrShort) // ignore message originating from us
return;
// use bidirectional quality indicator
if (!_neighbourTable.IsNeighbor(srcAddr.ShortAddress, out lqi))
lqi = 0;
if (lqi < rm.MinLQI)
rm.MinLQI = lqi;
bool usefull = _routingTable.UpdateRoute(rm.OriginatorAddr, srcAddr.ShortAddress,
rm.SeqNo, rm.HopCount, rm.MinLQI);
bool send = false;
if (rm.TargetAddr == _addrShort)
{
// message directed to us
if (usefull && rm.IsRequest)
{
// respond to message
Message.RoutingMessage rrep = new Message.RoutingMessage();
rrep.IsRequest = false;
rrep.HopsLeft = cDefaultHopLimit;
rrep.HopCount = 0;
rrep.MinLQI = 0xFF;
rrep.SeqNo = _seqNoDYMO;
rrep.TargetAddr = rm.OriginatorAddr;
rrep.OriginatorAddr = _addrShort;
rm = rrep;
send = true;
}
}
else
{
// message directed to someone else.
// alays forward route response, forward route request when usefull
if (!rm.IsRequest)
usefull = true;
if (usefull && rm.HopsLeft > 0)
{
rm.HopsLeft--;
send = true;
}
}
if (send)
{
if (rm.IsRequest)
{
SendRoutingMessage(rm); // RReq is broadcast
}
else
{ // RRep is unicast
UInt16 nextHop;
if (_routingTable.GetRoute(rm.TargetAddr, out nextHop))
{
SendRoutingMessage(rm);
}
else
{
// no route to forward this message. someone has a stale routing table!
SendRouteError(rm.OriginatorAddr, rm.TargetAddr, true /*fatal*/);
}
}
}
}
}