private static byte[] GetPeerHandshakeMessage(ExtendedTorrent torrent, string peerId)
{
byte[] handshake = new byte[49 + BitTorrentProtocol.ProtocolNameLength];
handshake[0] = Convert.ToByte(BitTorrentProtocol.ProtocolNameLength);
Array.Copy(BitTorrentProtocol.ProtocolNameBytes, 0, handshake, 1, BitTorrentProtocol.ProtocolNameLength);
Array.Copy(BitConverter.GetBytes((long)0), 0, handshake, BitTorrentProtocol.ProtocolNameLength + 1,
8); //reserved
Array.Copy(torrent.GetInfoHashBytes(), 0, handshake, BitTorrentProtocol.ProtocolNameLength + 9, 20);
Array.Copy(Encoding.ASCII.GetBytes(peerId), 0, handshake, BitTorrentProtocol.ProtocolNameLength + 29, 20);
return(handshake);
}
/*TBC
* public static byte[] GetAnnounceRequestPacket(byte[] connectionId, byte[] transactionId, Torrent torrent, int localPort)
* {
* byte[] announcePacket = new byte[98];
* Array.Copy(connectionId, 0, announcePacket, 0, 8);
* Array.Copy(BitConverter.GetBytes(1).Reverse().ToArray(), 0, announcePacket, 8, 4);//action
* Array.Copy(transactionId, 0, announcePacket, 12, 4);
* Array.Copy(torrent.GetInfoHashBytes(), 0, announcePacket, 16, 20);
* Array.Copy(Encoding.ASCII.GetBytes(GeneratePeerId()), 0, announcePacket, 36, 20);
* Array.Copy(BitConverter.GetBytes(torrent).Reverse().ToArray(), 0, announcePacket, 56, 8);//downloaded
* Array.Copy(BitConverter.GetBytes(torrent.Left).Reverse().ToArray(), 0, announcePacket, 64, 8);//left
* Array.Copy(BitConverter.GetBytes(torrent.Uploaded).Reverse().ToArray(), 0, announcePacket, 72, 8);//uploaded
*
* //4bytes: event (0) + 4bytes: ip addr (0)
* Array.Copy(BitConverter.GetBytes((long)0), 0, announcePacket, 80, 8);
* byte[] key = BitConverter.GetBytes(new Random().Next(0, int.MaxValue)).Reverse().ToArray();
* Array.Copy(key, 0, announcePacket, 88, 4);
* Array.Copy(BitConverter.GetBytes(-1).Reverse().ToArray(), 0, announcePacket, 92, 4);
* Array.Copy(BitConverter.GetBytes((ushort)localPort).Reverse().ToArray(), 0, announcePacket, 96, 2);
* return announcePacket;
* }*/
private static byte[] GetAnnounceRequestPacketZero(byte[] connectionId, byte[] transactionId, ExtendedTorrent torrent, int localPort, string peerId)
{
byte[] announcePacket = new byte[98];
Array.Copy(connectionId, 0, announcePacket, 0, 8);
Array.Copy(BitConverter.GetBytes(1).Reverse().ToArray(), 0, announcePacket, 8, 4);//action 1 - announce
Array.Copy(transactionId, 0, announcePacket, 12, 4);
Array.Copy(torrent.GetInfoHashBytes(), 0, announcePacket, 16, 20);
Array.Copy(Encoding.ASCII.GetBytes(peerId), 0, announcePacket, 36, 20);
Array.Copy(BitConverter.GetBytes((long)0), 0, announcePacket, 56, 8); //downloaded
Array.Copy(BitConverter.GetBytes(torrent.TotalSize).Reverse().ToArray(), 0, announcePacket, 64, 8); //left
Array.Copy(BitConverter.GetBytes((long)0), 0, announcePacket, 72, 8); //event 0-none
//4bytes: event (0) + 4bytes: ip addr (0)
Array.Copy(BitConverter.GetBytes((long)0), 0, announcePacket, 80, 8);
byte[] key = BitConverter.GetBytes(new Random().Next(0, int.MaxValue)).Reverse().ToArray();
Array.Copy(key, 0, announcePacket, 88, 4);
Array.Copy(BitConverter.GetBytes(-1), 0, announcePacket, 92, 4);//default
Array.Copy(BitConverter.GetBytes((ushort)localPort).Reverse().ToArray(), 0, announcePacket, 96, 2);
return(announcePacket);
}
private static int ValidatePeerHandshake(byte[] response, int responseLength, ExtendedTorrent torrent)
{
int peerPstrLength = Convert.ToInt32(response[0]);
if (responseLength < peerPstrLength + 49)
{
return(1); //possible keep alive message
}
if (peerPstrLength != BitTorrentProtocol.ProtocolNameLength)
{
return(2);
}
byte[] peerProtocolNamebytes = response.SubArray(1, peerPstrLength);
if (!peerProtocolNamebytes.SequenceEqual(BitTorrentProtocol.ProtocolNameBytes))
{
return(2); //not BitTorrentProtocol
}
byte[] receivedInfoHash = response.SubArray(peerPstrLength + 9, 20);
if (!receivedInfoHash.SequenceEqual(torrent.GetInfoHashBytes()))
{
return(3); //bad info hash
}
return(0); //handshake correct
}