public void SendSynAck()
{
var rph = RPH.CreateSynAckPacket();
var dgram = rph.Serialize();
SetChecksum(ref dgram);
_udpClient.Send(dgram, dgram.Length, _sender);
_currentState = State.ReceivePacket;
}
public void SetChecksum(ref byte[] packet)
{
RPH rph = RPH.Deserialize(packet);
var md5 = MD5.Create();
rph._checksum = BitConverter.ToInt32(md5.ComputeHash(packet), 0);
byte[] newHead = rph.Serialize();
Array.Copy(newHead, packet, newHead.Length);
}
public bool IsCorrupt(RPH rph)
{
int checksum = rph._checksum;
rph._checksum = 0;
byte[] packet = rph.Serialize();
var md5 = MD5.Create();
int calcChecksum = BitConverter.ToInt32(md5.ComputeHash(packet), 0);
return(checksum != calcChecksum);
}
public static RPH CreateAckPacket(int ackNr, int seqNr)
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = ackNr,
_fileSize = 0,
_syn = false,
_ack = true,
_fileEnding = ""
};
return(rph);
}
public static RPH CreateNAckPacket()
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 0,
_fileSize = 0,
_syn = false,
_ack = false,
_fileEnding = ""
};
return(rph);
}
public static RPH CreateSynPacket(int fileSize)
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 0,
_fileSize = fileSize,
_syn = true,
_ack = false,
_fileEnding = ""
};
return(rph);
}
public static RPH CreateNAckPacket()
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 0,
_fileSize = 0,
_syn = false,
_ack = false,
_fileEnding = ""
};
return rph;
}
public static RPH CreateAckPacket(int ackNr, int seqNr)
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = ackNr,
_fileSize = 0,
_syn = false,
_ack = true,
_fileEnding = ""
};
return rph;
}
public static RPH CreateSynAckPacket()
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 1,
_fileSize = 0,
_syn = true,
_ack = true,
_fileEnding = ""
};
return(rph);
}
public bool IsCorrupt(byte[] packet)
{
var copyPacket = new byte[packet.Length];
Array.Copy(packet, copyPacket, packet.Length);
var recvRph = RPH.Deserialize(packet);
int recvChecksum = recvRph._checksum;
recvRph._checksum = 0;
byte[] newHead = recvRph.Serialize();
Array.Copy(newHead, copyPacket, newHead.Length);
var md5 = MD5.Create();
int calcChecksum = BitConverter.ToInt32(md5.ComputeHash(copyPacket), 0);
return(calcChecksum != recvChecksum);
}
public bool Init()
{
_acknowledgedBytes = 0;
_fileEnding = "";
_fileRecv = false;
NrPackets = 0;
DisplayServerInformation();
Console.WriteLine("Warte auf Verbindung von Clienten...");
_sender = new IPEndPoint(IPAddress.Any, 0);
IPEndPoint endAddress = new IPEndPoint(IPAddress.Any, ListenPort);
try
{
if (_udpClient == null)
{
_udpClient = new UdpClient(endAddress);
}
byte[] dgram = _udpClient.Receive(ref _sender);
RPH rph = RPH.Deserialize(dgram);
if (IsCorrupt(rph))
{
// send nak
return(false);
}
else
{
_currentState = State.SendSynAck;
}
_fileEnding = rph._fileEnding;
_payloadBuffer = new byte[rph._fileSize];
return(true);
}
catch (SocketException e)
{
Console.WriteLine(e);
return(false);
}
}
static public RPH Deserialize(byte[] header)
{
var myPacket = new RPH();
using (var m = new MemoryStream(header))
{
using (var reader = new BinaryReader(m))
{
myPacket._checksum = reader.ReadInt32();
myPacket._seqNr = reader.ReadInt32();
myPacket._ackNr = reader.ReadInt32();
myPacket._fileSize = reader.ReadInt32();
myPacket._fileEnding = reader.ReadString();
myPacket._syn = reader.ReadBoolean();
myPacket._ack = reader.ReadBoolean();
}
return(myPacket);
}
}
public void AckPacket(byte[] buf)
{
// Deserialize our protocol
var rph = RPH.Deserialize(buf);
// Calculate the size of our protocol
int headSize = rph.GetByteLength();
// if received packet is a retransmission or corrupt or packet reordering took place
if (IsCorrupt(buf) || _acknowledgedBytes != rph._seqNr)
{
// Send NAck
Console.WriteLine("Packet was corrupt or it was a retransmission");
var ack = RPH.CreateNAckPacket();
var dgram = ack.Serialize();
SetChecksum(ref dgram);
_udpClient.Send(dgram, dgram.Length, _sender);
}
else if (!IsCorrupt(buf) && rph._seqNr == _acknowledgedBytes)
{
_acknowledgedBytes = rph._seqNr + buf.Length - headSize;
// Copy received bytes into receive buffer
Array.Copy(buf, headSize, _payloadBuffer, rph._seqNr, buf.Length - headSize);
var ack = RPH.CreateAckPacket(_acknowledgedBytes, 0);
var dgram = ack.Serialize();
SetChecksum(ref dgram);
_udpClient.Send(dgram, dgram.Length, _sender);
if (_payloadBuffer.Length == _acknowledgedBytes)
{
_currentState = State.SaveToFile;
}
}
else
{
Console.WriteLine("Not defined");
}
NrPackets++;
// Console.WriteLine(NrPackets + ".Paket");
// Console.WriteLine("Sequenznummer: " + rph._seqNr);
// Console.WriteLine("AckNr: " + _acknowledgedBytes);
}
public static RPH CreateSynAckPacket()
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 1,
_fileSize = 0,
_syn = true,
_ack = true,
_fileEnding = ""
};
return rph;
}
public bool IsSyn(RPH rph)
{
return(!IsCorrupt(rph) && rph._syn);
}
public static int GetPacketByteLength()
{
RPH rph = new RPH();
return(rph.GetByteLength());
}
public static int GetPacketByteLength()
{
RPH rph = new RPH();
return rph.GetByteLength();
}
public static RPH Deserialize(byte[] header)
{
var myPacket = new RPH();
using (var m = new MemoryStream(header))
{
using (var reader = new BinaryReader(m))
{
myPacket._checksum = reader.ReadInt32();
myPacket._seqNr = reader.ReadInt32();
myPacket._ackNr = reader.ReadInt32();
myPacket._fileSize = reader.ReadInt32();
myPacket._fileEnding = reader.ReadString();
myPacket._syn = reader.ReadBoolean();
myPacket._ack = reader.ReadBoolean();
}
return myPacket;
}
}
public static RPH CreateSynPacket(int fileSize)
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 0,
_fileSize = fileSize,
_syn = true,
_ack = false,
_fileEnding = ""
};
return rph;
}
public bool IsSyn(RPH rph)
{
return !IsCorrupt(rph) && rph._syn;
}
public bool IsCorrupt(RPH rph)
{
int checksum = rph._checksum;
rph._checksum = 0;
byte[] packet = rph.Serialize();
var md5 = MD5.Create();
int calcChecksum = BitConverter.ToInt32(md5.ComputeHash(packet), 0);
return checksum != calcChecksum;
}
