internal override void HandleReceivedFragment(FragmentHeader header, ref Frame payload)
{
if (header.FragmentSeqNumber == _lastFragmentSeqNumberReceived)
{
#if PRINTALL
Trace.Print("Already received this fragment. Drop.");
#endif
Frame.Release(ref payload);
return;
}
_lastFragmentSeqNumberReceived = header.FragmentSeqNumber;
if ((header.Type != FragmentType.ACK) || (header.MessageSeqNumber != _messageSeqNumber))
{
Frame.Release(ref payload);
return;
}
FragmentationMessageTerminatedEventArgs messageTerminatedHandlerArgs = null;
bool sendData = false;
lock (_lock)
{
if (_currentState == FragmentationMessageState.Disposed)
{
Frame.Release(ref payload);
return;
}
bool timerWasEnabled = _timerEnabled;
if (_timerEnabled)
{
_timer.UnregisterItem(this);
_timerEnabled = false;
}
_nbTimeoutWithoutAck = 0;
if (header.Type == FragmentType.ACK)
{
#if PRINTALL
Trace.Print("Received ACK for message " + header.MessageSeqNumber + " sduHandle=" + _sduHandle);
#endif
_nbFragmentsSentWithoutAck = 0;
BitArray fragmentMissingTable;
byte lastFragmentSeqNumberReceivedByReceived = 255;
try
{
Fragment.DecodeAckPayload(ref payload, out lastFragmentSeqNumberReceivedByReceived, out fragmentMissingTable);
Frame.Release(ref payload);
if (fragmentMissingTable.Length == _successfullyTransmittedFragments.Length)
{
BitArray fragmentReceived = fragmentMissingTable.Clone();
fragmentReceived.Not();
#if PRINTALL
string msg = "";
for (int i = 0; i < fragmentReceived.Length; i++)
{
if (fragmentReceived.Get(i))
{
msg += i + ",";
}
}
Trace.Print("received so far: " + msg);
#endif
_successfullyTransmittedFragments.Or(fragmentReceived);
if (_successfullyTransmittedFragments.CheckAllSet(true))
{
_allFragmentTransmitted = true;
_currentState = FragmentationMessageState.Final;
}
// now check if we received ACK for the last fragment that we sent.
if (lastFragmentSeqNumberReceivedByReceived == _lastFragmentSeqNumberSent)
{
long roundTripTime = (DateTime.Now.Ticks - _timeLastFragmentSent.Ticks) / TimeSpan.TicksPerMillisecond;
if (2 * roundTripTime <= (long)uint.MaxValue)
{
_timeoutForResending = (uint)(2 * roundTripTime);
}
_maxFragmentsBeforeAck++;
}
_lastFragmentSent.SetAll(false);
}
}
catch (ArgumentException)
{
// could not decode payload.
if (timerWasEnabled)
{
_timer.RegisterItem(_timeoutTicks, this);
_timerEnabled = true;
}
Frame.Release(ref payload);
return;
}
if (_allFragmentTransmitted)
{
_currentState = FragmentationMessageState.Final;
messageTerminatedHandlerArgs = new FragmentationMessageTerminatedEventArgs(_currentState, Status.Success);
}
else
{
sendData = true;
}
}
else
{
#if DEBUG
Trace.Print("Received bad fragment type for message " + header.MessageSeqNumber + " sdhHandle=" + _sduHandle);
#endif
Frame.Release(ref payload);
if (timerWasEnabled)
{
_timer.RegisterItem(_timeoutTicks, this);
_timerEnabled = true;
}
}
}
// release the lock before calling OnFragmentationMessageFinalState since upper layer handler is called.
if (messageTerminatedHandlerArgs != null)
{
OnFragmentationMessageTerminated(messageTerminatedHandlerArgs);
}
else if (sendData)
{
SendNextDataFragment(false);
}
}
/// <summary>
/// Start sending segments.
/// <param name="force">send a fragment in all case if true, do not send if no fragment pending</param>
/// </summary>
override internal void SendNextDataFragment(bool force)
{
Frame fragment;
ushort target;
byte pduHandle;
lock (_lock)
{
if (_timerEnabled)
{
_timer.UnregisterItem(this);
_timerEnabled = false;
}
if ((_currentState == FragmentationMessageState.Disposed) || (_allFragmentTransmitted))
{
return;
}
// for broadcast message, we send fragment one by one to make sure that they are properly sent.
byte indexOfFragmentToSend = 0;
bool fragmentFound = false;
bool lastFragmentToBeSent = true;
for (int i = 0; i < _endingIndices.Length; i++)
{
if (!_successfullyTransmittedFragments.Get(i) && !_lastFragmentSent.Get(i))
{
if (fragmentFound)
{
lastFragmentToBeSent = false;
break;
}
indexOfFragmentToSend = (byte)i;
fragmentFound = true;
}
}
bool alreadySentAll = false;
if (!fragmentFound)
{
if (force)
{
// no segment to send. Resent last one.
alreadySentAll = true;
indexOfFragmentToSend = (byte)(_endingIndices.Length - 1);
}
else
{
// no fragment to send. Wait for ack.
_timeoutTicks = DateTime.Now.Ticks + _timeoutForResending * TimeSpan.TicksPerMillisecond;
_timerId = _timer.RegisterItem(_timeoutTicks, this);
_timerEnabled = true;
_currentState = FragmentationMessageState.WaitingAck;
return;
}
}
bool requireAck = false;
byte fragmentSeqNumber = ++_lastFragmentSeqNumberSent;
if ((!_isBroadcast) && (lastFragmentToBeSent || (_nbFragmentsSentWithoutAck + 1 >= _maxFragmentsBeforeAck) || alreadySentAll))
{
requireAck = true;
}
int startIndexInSdu = (indexOfFragmentToSend == 0) ? 0 : _endingIndices[indexOfFragmentToSend - 1] + 1;
int endIndexInSdu = _endingIndices[indexOfFragmentToSend];
fragment = Fragment.CreateDataFrame(_messageSeqNumber, fragmentSeqNumber, _isBroadcast, requireAck,
_maxPduSize, _reservedTailSize, _reservedHeaderSize,
_nbFragments, indexOfFragmentToSend, _sdu, startIndexInSdu, endIndexInSdu - startIndexInSdu + 1);
_nbFragmentsSentWithoutAck++;
_nbFragmentsTransmittedLastSendTransition = 0;
_lastFragmentSent.Set(indexOfFragmentToSend, true);
#if PRINTALL
Trace.Print("Sending part " + indexOfFragmentToSend + "/" + _endingIndices.Length.ToString() + " of packet " + _messageSeqNumber);
#endif
_currentState = FragmentationMessageState.WaitingSentStatus;
pduHandle = _pduHandle++;
target = _destination;
_nbTransmissions++;
_nbFragmentsTransmittedLastSendTransition++;
// already set time of last fragment sent, but update when receive sent confirmation.
// this prevent the situation where the ACK is actually handled before the send confirmation
_timeLastFragmentSent = DateTime.Now;
}
// release lock before calling lower layer handler.
_lowerLayerRequestHandler(target, ref fragment, pduHandle, this.HandleSendConfirmation);
Frame.Release(ref fragment);
return;
}
