private async Task <byte[]> GetConnectionIdAsync(Socket udpSocket, SocksProxyUdpAssociateHandler proxyHandler, EndPoint trackerEP, byte[] transactionID)
{
//Connection_id 64bit 0x41727101980 + action 32bit + transaction_id 32bit (random)
byte[] request = new byte[] { 0x0, 0x0, 0x4, 0x17, 0x27, 0x10, 0x19, 0x80, 0x0, 0x0, 0x0, 0x0, transactionID[0], transactionID[1], transactionID[2], transactionID[3] };
byte[] response = new byte[128];
int responseLength;
if (_proxy == null)
{
responseLength = await udpSocket.UdpQueryAsync(request, response, await trackerEP.GetIPEndPointAsync(), TIMEOUT, 3, true);
}
else
{
responseLength = await proxyHandler.UdpQueryAsync(request, response, await trackerEP.GetIPEndPointAsync(), TIMEOUT, 3, true);
}
//check response length
if (responseLength < 16)
{
throw new TrackerClientException("Invalid response received for connection request.");
}
//check transaction id
for (int j = 0; j < 4; j++)
{
if (response[4 + j] != transactionID[j])
{
throw new TrackerClientException("Invalid transaction id received for connection request.");
}
}
//check action
for (int j = 0; j < 4; j++)
{
if (response[j] != 0)
{
throw new TrackerClientException("Invalid action received for connection request.");
}
}
byte[] connectionID = new byte[8];
Buffer.BlockCopy(response, 8, connectionID, 0, 8);
return(connectionID);
}
protected override async Task UpdateTrackerAsync(TrackerClientEvent @event, IPEndPoint clientEP)
{
SocksProxyUdpAssociateHandler proxyHandler = null;
Socket udpSocket = null;
EndPoint trackerEP = new DomainEndPoint(_trackerURI.Host, _trackerURI.Port);
if (_proxy == null)
{
trackerEP = await trackerEP.GetIPEndPointAsync();
udpSocket = new Socket(trackerEP.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
}
else
{
switch (_proxy.Type)
{
case NetProxyType.Socks5:
proxyHandler = await(_proxy as SocksProxy).UdpAssociateAsync();
break;
default:
throw new NotSupportedException("Proxy type is not supported by Udp tracker.");
}
}
try
{
for (int n = 0; n < 2; n++)
{
if ((_connectionId == null) || (_connectionIdExpires <= DateTime.UtcNow))
{
//GET CONNECTION ID
_rnd.GetBytes(_transactionID);
_connectionId = await GetConnectionIdAsync(udpSocket, proxyHandler, trackerEP, _transactionID);
_connectionIdExpires = DateTime.UtcNow.AddMinutes(1);
}
try
{
_rnd.GetBytes(_transactionID);
byte[] announceResponse = await GetAnnounceResponseAsync(udpSocket, proxyHandler, trackerEP, _transactionID, _connectionId, @event, clientEP);
byte[] buffer = new byte[4];
Buffer.BlockCopy(announceResponse, 8, buffer, 0, 4);
Array.Reverse(buffer);
_interval = BitConverter.ToInt32(buffer, 0);
Buffer.BlockCopy(announceResponse, 12, buffer, 0, 4);
Array.Reverse(buffer);
_leachers = BitConverter.ToInt32(buffer, 0);
Buffer.BlockCopy(announceResponse, 16, buffer, 0, 4);
Array.Reverse(buffer);
_seeders = BitConverter.ToInt32(buffer, 0);
_peers.Clear();
if (_proxy == null)
{
if (udpSocket.AddressFamily == AddressFamily.InterNetworkV6)
{
ParsePeersIPv6(announceResponse, announceResponse.Length, _peers);
}
else
{
ParsePeersIPv4(announceResponse, announceResponse.Length, _peers);
}
}
else
{
int x = (announceResponse.Length - 26) % 6;
if (x == 0)
{
ParsePeersIPv4(announceResponse, announceResponse.Length, _peers);
}
else
{
ParsePeersIPv6(announceResponse, announceResponse.Length, _peers);
}
}
return;
}
catch (SocketException ex)
{
if (ex.ErrorCode != (int)SocketError.TimedOut)
{
throw new TrackerClientException(ex.Message, ex);
}
}
}
throw new TrackerClientException("No response from tracker.");
}
finally
{
if (proxyHandler != null)
{
proxyHandler.Dispose();
}
if (udpSocket != null)
{
udpSocket.Close();
}
}
}
private async Task <byte[]> GetAnnounceResponseAsync(Socket udpSocket, SocksProxyUdpAssociateHandler proxyHandler, EndPoint trackerEP, byte[] transactionID, byte[] connectionID, TrackerClientEvent @event, IPEndPoint clientEP)
{
byte[] request = new byte[98];
{
//connection_id 64bit
Buffer.BlockCopy(connectionID, 0, request, 0, 8);
//action 32bit
request[11] = 1;
//transaction_id 32bit
Buffer.BlockCopy(transactionID, 0, request, 12, 4);
//info_hash 20 bytes
Buffer.BlockCopy(_infoHash, 0, request, 16, 20);
//peer_id 20 bytes
Buffer.BlockCopy(_clientID.PeerID, 0, request, 36, 20);
//downloaded 64bit
//left 64bit
//uploaded 64bit
//event 32bit
request[83] = Convert.ToByte(@event);
//ip address 32bit
if (clientEP.Address.AddressFamily == AddressFamily.InterNetwork)
{
switch (clientEP.Address.ToString())
{
case "0.0.0.0":
case "127.0.0.1":
break;
default:
Buffer.BlockCopy(clientEP.Address.GetAddressBytes(), 0, request, 84, 4);
break;
}
}
//key 32bit
Buffer.BlockCopy(_clientID.ClientKey, 0, request, 88, 4);
//num_want
Buffer.BlockCopy(BitConverter.GetBytes(_clientID.NumWant), 0, request, 92, 4);
//port 16bit
byte[] portBuffer = BitConverter.GetBytes(clientEP.Port);
Array.Reverse(portBuffer);
Buffer.BlockCopy(portBuffer, 2, request, 96, 2);
}
byte[] buffer = new byte[1024];
int bytesReceived;
if (_proxy == null)
{
bytesReceived = await udpSocket.UdpQueryAsync(request, buffer, await trackerEP.GetIPEndPointAsync(), TIMEOUT, 3, true);
}
else
{
bytesReceived = await proxyHandler.UdpQueryAsync(request, buffer, await trackerEP.GetIPEndPointAsync(), TIMEOUT, 3, true);
}
//check response length
if (bytesReceived < 20)
{
throw new TrackerClientException("Invalid response received for announce request.");
}
//check response transaction id
for (int j = 0; j < 4; j++)
{
if (buffer[4 + j] != transactionID[j])
{
throw new TrackerClientException("Invalid transaction id received for announce request.");
}
}
//check response action
if (buffer[3] != 1)
{
throw new TrackerClientException("Invalid action received for announce request.");
}
byte[] response = new byte[bytesReceived];
Buffer.BlockCopy(buffer, 0, response, 0, bytesReceived);
return(response);
}
