public void WaitForSynAck()
{
EndPoint sender = (EndPoint)_endPoint;
var ackn = new byte[RPH.GetPacketByteLength()];
// set the timeout for receiving acks (retransmission timeout)
_sendingSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, Timeout);
try
{
_sendingSocket.ReceiveFrom(ackn, ref sender);
var rph = RPH.Deserialize(ackn);
if (IsCorrupt(rph) || !IsSynAck(rph))
{
_currentState = State.EstablishConnection;
return;
}
else
{
Console.WriteLine("Connection Established");
_currentState = State.SendPacket;
}
}
catch (SocketException e)
{
if (e.SocketErrorCode == SocketError.TimedOut)
{
Console.WriteLine(e.ToString());
Console.WriteLine("No Connection could be established");
}
_currentState = State.EstablishConnection;
}
}
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);
}
private void WaitForAck()
{
EndPoint sender = (EndPoint)_endPoint;
var ackn = new byte[RPH.GetPacketByteLength()];
_tries++;
if (MaxRetransTries < _tries)
{
_currentState = State.FatalError;
return;
}
try
{
_sendingSocket.ReceiveFrom(ackn, ref sender);
var rph = RPH.Deserialize(ackn);
// Ack is corrupt
if (IsCorrupt(rph, ackn) || !IsAck(rph))
{
// If Ack is corrupt resend Packet
Console.WriteLine("Corrupt or NAck: Resend Packet");
}
else if (IsAck(rph) && !IsCorrupt(rph) && rph._ackNr != _localSeqNr)
{
_tries = 0;
Debug.Assert(rph != null, "rph != null");
_localSeqNr += _filechunk.Length;
_currentState = State.SendPacket;
}
else
{
Console.WriteLine("Not defined");
}
}
catch (SocketException e)
{
if (e.SocketErrorCode == SocketError.TimedOut)
{
// Timeout: Resend Packet
Console.WriteLine("Timeout: Resend Packet");
SendOnePacket();
}
else
{
Console.WriteLine("Fatal Error");
_currentState = State.FatalError;
return;
}
}
}
public static RPH CreateSynAckPacket()
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 1,
_fileSize = 0,
_syn = true,
_ack = true
};
return(rph);
}
public static RPH CreateSynAckPacket()
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 1,
_fileSize = 0,
_syn = true,
_ack = true
};
return rph;
}
public static RPH CreatePacketHeader(int seqNr, int ackNr)
{
RPH rph = new RPH
{
_seqNr = seqNr,
_ackNr = ackNr,
_syn = false,
_fileSize = 0,
_ack = true
};
return rph;
}
public static RPH CreatePacketHeader(int seqNr, int ackNr)
{
RPH rph = new RPH
{
_seqNr = seqNr,
_ackNr = ackNr,
_syn = false,
_fileSize = 0,
_ack = true
};
return(rph);
}
public static RPH CreateSynPacket(int fileSize, string fileEnding)
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 0,
_fileSize = fileSize,
_syn = true,
_ack = false,
_fileEnding = fileEnding
};
return(rph);
}
public bool IsCorrupt(RPH rph, 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);
}
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 SendSyn(int filelength, string fileEnding)
{
// Establish the connection
RPH syn = RPH.CreateSynPacket(filelength, fileEnding);
byte[] dgram = syn.Serialize();
SetChecksum(ref dgram);
try
{
_sendingSocket?.SendTo(dgram, _endPoint);
}
catch (SocketException e)
{
Console.WriteLine(e.ToString());
_tries++;
if (_tries > MaxConTries)
{
return;
}
SendSyn(filelength, fileEnding);
_tries = 0;
}
}
private void SendOnePacket()
{
int headSize = RPH.GetPacketByteLength();
byte[] packetBuf = null;
if (!IsLastPacket(PacketSizeBytes - headSize))
{
_filechunk = FileToChunk(_fileData, _localSeqNr, PacketSizeBytes - headSize);
packetBuf = new byte[PacketSizeBytes];
}
else
{
_filechunk = FileToChunk(_fileData, _localSeqNr, _fileData.Length - _localSeqNr);
packetBuf = new byte[_filechunk.Length + headSize];
_fileSend = true;
}
var rph = RPH.CreatePacketHeader(_localSeqNr, 0);
byte[] header = rph.Serialize();
// Copy together one packet: header with payload
Array.Copy(header, packetBuf, headSize);
Array.Copy(_filechunk, 0, packetBuf, headSize, _filechunk.Length);
// Last set the Checksum of the packet
SetChecksum(ref packetBuf);
// Now Send the packet
_sendingSocket.SendTo(packetBuf, _endPoint);
Console.WriteLine("Paket versendet");
// Change State
_currentState = State.WaitForAck;
}
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, string fileEnding)
{
RPH rph = new RPH
{
_seqNr = 0,
_ackNr = 0,
_fileSize = fileSize,
_syn = true,
_ack = false,
_fileEnding = fileEnding
};
return rph;
}
public static int GetPacketByteLength()
{
RPH rph = new RPH();
return(rph.GetByteLength());
}
public bool IsSynAck(RPH rph)
{
return rph._ack && rph._syn && rph._ackNr == 1;
}
public bool IsCorrupt(RPH rph, 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 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 bool IsAck(RPH rph)
{
return rph._ack && !rph._syn;
}
public bool IsSynAck(RPH rph)
{
return(rph._ack && rph._syn && rph._ackNr == 1);
}
public static int GetPacketByteLength()
{
RPH rph = new RPH();
return rph.GetByteLength();
}
public bool IsAck(RPH rph)
{
return(rph._ack && !rph._syn);
}