/// <summary>
/// Sends byte[] to socket.
/// Creates datagram with frame format given as example in demonstration example.
/// Switches state to waitingforack.
/// Set sendAsIs when sending/resending valid datagram/frame.
/// </summary>
/// <param name="data">Byte array to be sent over socket</param>
/// <param name="sendAsIs">Boolen: true - datagram has been contructed before, false - construct new datagram and send it</param>
protected virtual async void RdtSend(byte[] data, bool sendAsIs = false)
{
if (sendAsIs)
{
socket.Send(data);
}
else
{
switch (state)
{
case (int)STATE.WaitingCallFromAboveOrBelow:
{
byte[] newDatagram = rdt.MakeDatagram(data, senderSeq);
socket.Send(newDatagram);
previouslySentDatagram = newDatagram;
state = (int)STATE.WaitingForAck;
break;
}
case (int)STATE.WaitingForAck:
{
RaiseOnDeliver(InvokeReason.Error, "Waiting for ACK/NACK, add to queue.");
messageBuffer.Add(data);
break;
}
}
}
}
private async void RdtSend(byte[] data, bool isOldDatagram = false)
{
if (isOldDatagram)
{
/*data has been sent before so it has seq nums etc*/
socket.Send(data);
}
else
{
/*data is just new content as byte[] so new datagram is needed*/
/*nextseqnum<base+N will fail when seqnum range overflows*/
if (rdt.Distmod(gbnBase, gbnNextSeqNum, gbnWindowSize) < gbnWindowSize - 1)
{
try
{
OnDeliver?.Invoke(InvokeReason.Debug, "4a" + PrintGbnDebug());
byte[] newDatagram = rdt.MakeDatagram(data, gbnNextSeqNum);
gbnSendDictionary[gbnNextSeqNum] = newDatagram;
socket.Send(gbnSendDictionary[gbnNextSeqNum]);
//simplify with pre-increment and combine following operations
gbnNextSeqNum = gbnNextSeqNum + 1;
gbnNextSeqNum = gbnNextSeqNum % gbnWindowSize;
OnDeliver?.Invoke(InvokeReason.Debug, "4b" + PrintGbnDebug());
if (cts != null)
{
cts.Cancel();
}
/*All standing packets are ack'd*/
if (gbnBase == gbnNextSeqNum)
{
//OnDeliver?.Invoke(InvokeReason.Debug, "Sending window is empty.");
}
else
{
//start new timer
//TODO: Check if this leaks resources
CancellationTokenSource aCTS = new CancellationTokenSource();
cts = aCTS;
await Timertimeout(aCTS.Token);
/*
* if (cts == aCTS)
* {
* cts = null;
* }
*/
}
}
catch (OperationCanceledException) { }
}
else //send window is full
{
OnDeliver?.Invoke(InvokeReason.Error, "Sending window is full, try again later.");
}
}
}
private void RdtReceive(byte[] datagram)
{
bool isOk = rdt.IsOk(datagram);
if (isOk)
{
string str = rdt.GetDatagramContentString(datagram);
bool isAck = rdt.IsAck(datagram);
byte seqNum = (byte)rdt.GetSeqNum(datagram);
if (isAck)
{
//Mark as ack'd
//If seq == sendBase => move window by:
//Go through buffer and if packets are in window and pkt.sent = false => send it and toggle bool
if (rdt.IsSeqInRange(seqNum, srSendBase, (byte)(srSendBase + srWindowSize - 1)))
{
sendBucket.MarkAsAcked(seqNum);
OnDeliver?.Invoke(InvokeReason.Debug, "Received ACK: " + seqNum.ToString()
+ PrintSRDebugInfo());
if (seqNum == srSendBase)
{
//int i = 0;
//While packet is sent -> remove it from sendBucket, increment counter, add counter to srSendBase
while (sendBucket.IsSent(srSendBase) && sendBucket.IsAcked(srSendBase))
{
sendBucket.RemoveFromBucket(srSendBase);
srSendBase++;
}
//While packet in sendBucket is in new window && hasn't been sent, send it and toggle it's state
//E.g for each srSendBase to srSendBase + N -1, if is in sendBucket & is not sent, send it now
//As dictionary is not ordered, we loop over range srSendBase -> srSendBase + N - 1. Stopping early if key isn't in bucket.
for (byte i = srSendBase; rdt.IsSeqInRange(i, srSendBase, (byte)(srSendBase + srWindowSize - 1)); i++)
{
if (!sendBucket.ContainsKey(i))
{
break;
}
socket.Send(sendBucket.GetDatagramBySeq(i));
sendBucket.MarkAsSent(i);
//srNextSeqNum++;
}
OnDeliver.Invoke(InvokeReason.Debug, "Sender window moved. " + PrintSRDebugInfo());
}
}
}
else
{
if (rdt.IsSeqInRange(seqNum, (byte)(srRcvBase - srWindowSize), (byte)(srRcvBase + srWindowSize - 1)))
{
RdtSend(rdt.MakeAck(seqNum), true);
OnDeliver?.Invoke(InvokeReason.Debug, "Received Pkt: " + seqNum.ToString()
+ PrintSRDebugInfo());
if (rdt.IsSeqInRange(seqNum, srRcvBase, (byte)(srRcvBase + srWindowSize - 1)))
{
if (!rcvBucket.ContainsKey(seqNum))
{
rcvBucket.AddToBucket(datagram, seqNum);
}
else
{
OnDeliver.Invoke(InvokeReason.Debug, "Received duplicate: " + seqNum.ToString());
}
if (seqNum == srRcvBase)
{
/*Pass a Action delegate for handling method. Method chain removes from buffer,
* handles packets, returns count of handled. Naming scheme I use is bad, I know :(*/
srRcvBase = (byte)(srRcvBase + ProcessValidBufferedSequence(srRcvBase,
DeliverDataSequenceToUpperLayer));
OnDeliver.Invoke(InvokeReason.Debug, "Receiver window moved. " + PrintSRDebugInfo());
}
}
}
}
}
else
{
//This Kurose implementation will ignore corrupted packets and relies on timeout to recover
//Alternative is to send SREPEAT-control message to request retransmission for seqnum-1 packet.
OnDeliver?.Invoke(InvokeReason.Error, "Received corrupted");
}
}
