public int RequestForNewPiece()
{
int piece = 0, offset = 0, length = 0;
if (!CurrentFile.GetNextMissingPiece(ref piece, ref offset, ref length))
{
return(-1);
}
if (!DifferenceBitField.GetPiece(piece))
{
#if DEBUG
Console.WriteLine("Cutting connection.. Peer does not have the piece");
#endif
return(-1); //does not have the piece
}
#if DEBUG
Console.WriteLine("Requesting for piece: {0}", piece);
#endif
byte[] pieceRequest = PacketGenerator.Request(piece, offset, length);
Send(pieceRequest);
State = PeerState.DOWNLOADING;
return(piece);
}
public static byte[] Unchoke()
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(1); //Length
rs.WriteByte(1); //ID
return(rs.GetByteArray());
}
public static byte[] NotInterested()
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(1); //Length
rs.WriteByte(3); //ID
return(rs.GetByteArray());
}
public void Have(byte[] data)
{
PacketGenerator gs = new PacketGenerator(data);
int piece = gs.ReadInt();
#if DEBUG
Console.WriteLine("Successfully uploaded piece {0}", piece);
#endif
}
public static byte[] BitField(byte[] bitfield)
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(1 + bitfield.Length); //Length
rs.WriteByte(5); //ID
rs.WriteByteArray(bitfield); //Payload: Bitfield
return(rs.GetByteArray());
}
public static byte[] Have(int piece)
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(5); //Length
rs.WriteByte(4); //ID
rs.WriteInt(piece); //Payload: Piece ID
return(rs.GetByteArray());
}
public static byte[] Port(short listen_port) //Used for DHT, currently unimplemented
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(3); //Length
rs.WriteByte(9); //ID
rs.WriteShort(listen_port);
return(rs.GetByteArray());
}
public static byte[] Cancel(int pieceid, int piece_begin_offset, int piecelength) //Same parameters as 'Request' message
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(13); //Length
rs.WriteByte(8); //ID
rs.WriteInt(pieceid); //Payload: Piece ID [index]
rs.WriteInt(piece_begin_offset); //Payload: Byte Offset [begin]
rs.WriteInt(piecelength); //Payload: Piece Read Length [length]
return(rs.GetByteArray());
}
public static byte[] Piece(int pieceid, int piece_begin_offset, byte[] piece_part) //WARNING: USE REQUESTED AMOUNT OF BYTES (MAX 16KB) AT A TIME, SEND IN MULTIPLE REQUESTS
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(9 + piece_part.Length); //Length
rs.WriteByte(7); //ID
rs.WriteInt(pieceid); //Payload: Piece ID [index]
rs.WriteInt(piece_begin_offset); //Payload: Byte Offset [begin]
rs.WriteByteArray(piece_part); //Payload: Piece Block [block]
return(rs.GetByteArray());
}
public static byte[] Request(int pieceid, int piece_begin_offset, int piecelength) //WARNING: USE 16 KILOBYTES (2^14) AT A TIME, DOWNLOAD IN MULTIPLE REQUESTS
{
PacketGenerator rs = new PacketGenerator();
rs.WriteInt(13); //Length
rs.WriteByte(6); //ID
rs.WriteInt(pieceid); //Payload: Piece ID [index]
rs.WriteInt(piece_begin_offset); //Payload: Byte Offset [begin]
rs.WriteInt(piecelength); //Payload: Piece Read Length [length]
return(rs.GetByteArray());
}
public static byte[] Handshake(string clientName, byte[] info_hash, string peer_id)
{
PacketGenerator rs = new PacketGenerator();
byte[] reservedBytes = { 0, 0, 0, 0, 0, 0, 0, 0 };
rs.WriteByte(Convert.ToByte(clientName.Length));
rs.WriteString(clientName);
rs.WriteByteArray(reservedBytes);
rs.WriteByteArray(info_hash);
rs.WriteString(peer_id);
return(rs.GetByteArray());
}
public void FetchAndSendPiece(byte[] packet)
{
PacketGenerator gs = new PacketGenerator(packet);
int pieceRequested = gs.ReadInt();
int pieceOffset = gs.ReadInt();
int length = gs.ReadInt();
byte[] fileData = new byte[1];
if (CurrentFile.ReadPiece(pieceRequested, ref fileData, pieceOffset, length))
{
#if DEBUG
Console.WriteLine("Sending piece: {0}", pieceRequested);
#endif
byte[] send = PacketGenerator.Piece(pieceRequested, pieceOffset, fileData);
Send(send);
}
}
public int SavePieceAndRequestForNewOne(byte[] packet)
{
PacketGenerator gs = new PacketGenerator(packet);
int piece = gs.ReadInt();
int pieceOffset = gs.ReadInt();
byte[] data = gs.ReadLeftoverByteArray();
CurrentFile.WritePiece(piece, pieceOffset, data);
Console.WriteLine("Received piece: {0} {1:0.000}%", piece, ((float)CurrentFile.GetDownloadedSize() / (float)CurrentFile.GetSize()) * 100.0);
if (data.Length < 1024 * 16)
{
byte[] have = PacketGenerator.Have(piece);
Send(have);
// Console.WriteLine("Successfully downloaded piece: {0}", piece);
}
return(RequestForNewPiece());
}
public bool Handshake(PacketGenerator gs)
{
int nameLength = (int)gs.ReadByte();
if (gs.GetLength() < 49 + nameLength)
{
#if DEBUG
Console.WriteLine("Invalid namelength! Corrupted packet?");
#endif
return(false);
}
string name = gs.ReadString(nameLength);
gs.SeekIndex(8); //reservedBytes
byte[] infoHash = gs.ReadByteArray(20);
string peerID = gs.ReadString(20);
bool HanshakeSuccess = infoHash.SequenceEqual(this.Infohash);
return(HanshakeSuccess);
}
public void ReadThread()
{
Stream.ReadTimeout = 40000;// 40s timeout
try
{
while (ThreadWorking)
{
Send(PacketGenerator.Interested());
Send(PacketGenerator.Unchoke());
if (State == PeerState.CHOKED)
{
if (ChokeTimer.GetElapsedSeconds() >= 30.0)
{
ThreadWorking = false;
break;
}
}
byte packetID = 0;
byte[] received = ReadPacket(ref packetID);
if (packetID <= 9)
{
AliveTimer.Reset();
}
#if DEBUG
Console.WriteLine("Received packet: {0}", packetID == 0xF0 ? "Keep-Alive" : Convert.ToString(packetID));
#endif
switch (packetID)
{
case 0xF0: //KEEP_ALIVE
//AliveTimer.Reset();
if (State == PeerState.READY)
{
if (RequestForNewPiece() == -1)
{
//all pieces downloaded or failed
State = PeerState.SHAKING;
ThreadWorking = false;
}
}
//SendPacket(null, 0);
break;
case 0: //CHOKE
ChokeTimer.Reset();
State = PeerState.CHOKED;
break;
case 1: //UNCHOKE
if (State == PeerState.CHOKED)
{
// Send(PacketGenerator.Interested());
//Console.WriteLine("Sent Interested Packet!");
if (RequestForNewPiece() == -1)
{
//all pieces downloaded or failed
State = PeerState.SHAKING;
ThreadWorking = false;
}
Send(PacketGenerator.Unchoke());
}
if (State == PeerState.CHOKED)
{
State = PeerState.READY;
}
break;
case 2: //INTERESTED
State = PeerState.READY;
if (RequestForNewPiece() == -1)
{
//all pieces downloaded or failed
State = PeerState.SHAKING;
ThreadWorking = false;
}
break;
case 3: //NOTINTERESTED
ThreadWorking = false;
#if DEBUG
Console.WriteLine("Killing thread.. Not interested.");
#endif
break;
case 4: //HAVE
Have(received); // OK
break;
case 5: //BITFIELD
BitField(received);
break;
case 6: //REQUEST
FetchAndSendPiece(received);
break;
case 7: //PIECE
State = PeerState.READY;
if (SavePieceAndRequestForNewOne(received) == -1)
{
//all pieces downloaded or failed
State = PeerState.SHAKING;
ThreadWorking = false;
}
break;
case 8: //CANCEL
//No need
break;
case 9: //PORT
//Unused
break;
}
}
}
catch (Exception e)
{
ThreadWorking = false;
#if DEBUG
Console.WriteLine("ThreadException: {0}", e.Message);
#endif
}
}
public bool BeginConnection()
{
Client = new TcpClient();
Client.ReceiveTimeout = 1000;
var result = Client.BeginConnect(this.IP, this.Port, null, null);
Console.WriteLine("Connecting to: {0}:{1}", this.IP, this.Port);
var success = result.AsyncWaitHandle.WaitOne(TimeSpan.FromSeconds(5));
if (!success || !Client.Connected)
{
return(false);
}
Stream = Client.GetStream();
Stream.ReadTimeout = 6000;
byte[] handshake = PacketGenerator.Handshake("BitTorrent protocol", Infohash, PeerClientID);
Stream.Write(handshake, 0, handshake.Length);
Stream.Flush();
#if DEBUG
Console.WriteLine("Sent packet!");
#endif
byte[] realRead = Read();
if (realRead.Length < 49)
{
#if DEBUG
Console.WriteLine("Invalid handshake packet! Exiting!");
#endif
Stream.Close();
Client.Close();
return(false);
}
#if DEBUG
Console.WriteLine("Received: {0} bytes", realRead.Length);
#endif
PacketGenerator gs = new PacketGenerator(realRead);
if (!Handshake(gs))
{
#if DEBUG
Console.WriteLine("Handshake failed!");
#endif
Stream.Close();
Client.Close();
return(false);
}
Console.WriteLine("Connected!");
State = PeerState.CHOKED;
ChokeTimer.Reset();
_ReadThread = new Thread(ReadThread);
_ReadThread.Start();
TimeManager resentTimer = new TimeManager();
while (ThreadWorking)
{
if (AliveTimer.GetElapsedSeconds() > 20.0 && resentTimer.GetElapsedSeconds() > 10.0)
{
resentTimer.Reset();
if (LastPacketSent == null)
{
Send(PacketGenerator.KeepAlive());
}
else
{
Send(LastPacketSent);
}
}
if (AliveTimer.GetElapsedSeconds() > 60.0)
{
ThreadWorking = false;
}
Thread.Sleep(100);
}
ThreadWorking = false;
return(true);
}
