/// <summary>
/// Reads a packet from a stream with the given size in bytes or returns null if the packet cannot be parsed.
/// </summary>
public static Packet Read(InStream Stream, int Size)
{
Packet packet = new Packet();
// Read flags and header
if ((Size -= StreamSize.Byte + StreamSize.Int) < 0)
return null;
PacketFlags flags = (PacketFlags)Stream.ReadByte();
packet.SequenceNumber = Stream.ReadInt();
packet.PingRequest = (flags & PacketFlags.PingRequest) == PacketFlags.PingRequest;
packet.PingResponse = (flags & PacketFlags.PingResponse) == PacketFlags.PingResponse;
// Read additional information
if ((flags & PacketFlags.Acknowledgement) == PacketFlags.Acknowledgement)
{
if ((Size -= StreamSize.Int) < 0)
return null;
packet.AcknowledgementNumber = Stream.ReadInt();
}
if ((flags & PacketFlags.RoundTripTime) == PacketFlags.RoundTripTime)
{
if ((Size -= StreamSize.Double) < 0)
return null;
packet.RoundTripTime = Stream.ReadDouble();
}
// Read chunk if any
if ((flags & PacketFlags.Chunk) == PacketFlags.Chunk)
{
packet.ChunkInitial = (flags & PacketFlags.ChunkInitial) == PacketFlags.ChunkInitial;
packet.ChunkFinal = (flags & PacketFlags.ChunkFinal) == PacketFlags.ChunkFinal;
byte[] data = new byte[Size];
Stream.Read(data, 0, data.Length);
packet.ChunkData = data;
return packet;
}
else
{
// A packet can only be a disconnect if it does not have a chunk
packet.Disconnect = (flags & PacketFlags.Disconnect) == PacketFlags.Disconnect;
// Make sure this is the end of the packet
if (Size == 0)
return packet;
else
return null;
}
}
/// <summary>
/// Writes a packet to a stream.
/// </summary>
public static void Write(Packet Packet, OutStream Stream)
{
// Build flags and header
PacketFlags flags = PacketFlags.Empty;
if (Packet.AcknowledgementNumber.HasValue)
flags |= PacketFlags.Acknowledgement;
if (Packet.RoundTripTime.HasValue)
flags |= PacketFlags.RoundTripTime;
if (Packet.ChunkData != null)
{
flags |= PacketFlags.Chunk;
if (Packet.ChunkInitial)
flags |= PacketFlags.ChunkInitial;
if (Packet.ChunkFinal)
flags |= PacketFlags.ChunkFinal;
}
if (Packet.PingRequest)
flags |= PacketFlags.PingRequest;
if (Packet.PingResponse)
flags |= PacketFlags.PingResponse;
if (Packet.Disconnect)
flags |= PacketFlags.Disconnect;
Stream.WriteByte((byte)flags);
Stream.WriteInt(Packet.SequenceNumber);
// Additional information
int ack;
if (Packet.AcknowledgementNumber.TryGetValue(out ack))
Stream.WriteInt(ack);
double rtt;
if (Packet.RoundTripTime.TryGetValue(out rtt))
Stream.WriteDouble(rtt);
// Chunk
if (Packet.ChunkData != null)
Stream.Write(Packet.ChunkData, 0, Packet.ChunkData.Length);
}
/// <summary>
/// Immediately sends a ping response packet of some sort.
/// </summary>
private void _SendPingResponse(UDPHub Hub)
{
byte[] data = null;
bool initial = false;
bool final = false;
int sequencenumber = 0;
Packet packet;
if(this._OutTerminal.Process(ref sequencenumber, ref data, ref initial, ref final))
{
packet = new Packet
{
SequenceNumber = sequencenumber,
ChunkData = data,
ChunkInitial = initial,
ChunkFinal = final
};
}
else
{
packet = new Packet
{
SequenceNumber = this._OutTerminal.SendNumber
};
}
packet.PingResponse = true;
Hub.Send(packet, this.EndPoint);
}
/// <summary>
/// Fills the given packet with additional information.
/// </summary>
private void _FillAdditional(Packet Packet)
{
if (this._ShouldSendAcknowledgement)
{
this._ShouldSendAcknowledgement = false;
Packet.AcknowledgementNumber = this.InTerminal.AcknowledgementNumber;
}
if (this._ShouldSendRoundTripTime)
{
this._ShouldSendRoundTripTime = false;
Packet.RoundTripTime = this.RoundTripTime;
}
}
/// <summary>
/// Updates the state of the peer and sends packets if needed.
/// </summary>
internal void _Update(UDPHub Hub, double Time, out bool Remove)
{
UDPHubSettings settings = this._Settings;
OutTerminal oterm = this._OutTerminal;
// Handle waves
this._WaveDelay -= Time;
if (this._WaveDelay <= 0.0)
{
// Check acknowledgement and adjust wave size
if (oterm.AcknowledgementNumber == oterm.SendNumber)
{
if (this._FullWave)
{
this._WaveSize++;
this._FullWave = false;
}
}
else
{
oterm.SendNumber = oterm.AcknowledgementNumber;
if (this._WaveSize > 1)
{
this._WaveSize--;
}
}
int chunksequencenumber = 0;
byte[] chunkdata = null;
bool chunkinitial = false;
bool chunkfinal = false;
int wavesize = 0;
if (oterm.Process(ref chunksequencenumber, ref chunkdata, ref chunkinitial, ref chunkfinal))
{
while (true)
{
// Send chunk
wavesize++;
Packet chunk = new Packet
{
SequenceNumber = chunksequencenumber,
ChunkData = chunkdata,
ChunkInitial = chunkinitial,
ChunkFinal = chunkfinal
};
this._FillAdditional(chunk);
Hub.Send(chunk, this._EndPoint);
// Check if wave is full
if (wavesize == this._WaveSize)
{
this._FullWave = true;
break;
}
// Get next chunk
if (!oterm.Process(ref chunksequencenumber, ref chunkdata, ref chunkinitial, ref chunkfinal))
{
break;
}
}
// Reset delays
this._WaveDelay = this._RoundTripTime + settings.WaveRate;
this._KeepAliveDelay = settings.KeepAliveDelay;
}
}
// Send keep alive if needed
this._KeepAliveDelay -= Time;
if (this._KeepAliveDelay <= 0.0)
{
Packet packet = new Packet
{
SequenceNumber = this._OutTerminal.SendNumber
};
this._FillAdditional(packet);
Hub.Send(packet, this.EndPoint);
this._KeepAliveDelay = settings.KeepAliveDelay;
}
// Check for implicit disconnect
Remove = false;
this._ExpireDelay -= Time;
if (this._ExpireDelay <= 0.0)
{
Remove = true;
}
}
/// <summary>
/// Called when an (unvalidated) packet is received for this peer.
/// </summary>
internal void _Receive(UDPHubSettings Settings, UDPHub Hub, Packet Packet, out bool Remove)
{
Remove = false;
// Validate
if (!this._Valid(Packet.SequenceNumber))
return;
// Disconnect?
if (Packet.Disconnect)
{
Remove = true;
return;
}
// Reset expire delay
this._ExpireDelay = Settings.ExpireDelay;
// Read additional information
int ack;
if (Packet.AcknowledgementNumber.TryGetValue(out ack))
{
this._OutTerminal.AcknowledgementNumber = ack;
}
double rtt;
if (Packet.RoundTripTime.TryGetValue(out rtt))
{
this._RoundTripTime = rtt;
}
// Chunk?
if (Packet.ChunkData != null)
{
this._Process(Packet.SequenceNumber, Packet.ChunkData, Packet.ChunkInitial, Packet.ChunkFinal);
}
// Ping?
if (Packet.PingRequest)
{
this._SendPingResponse(Hub);
}
}
/// <summary>
/// Uses the connection and settings of this hub to send a packet to the given endpoint.
/// </summary>
public void Send(Packet Packet, IPEndPoint To)
{
BufferOutStream bos = new BufferOutStream(this._Settings.SendBuffer, 0);
Packet.Write(Packet, bos);
this._UDP.Send(To, Data.FromBuffer(bos.Buffer, 0, bos.Position));
}
