public async Task HandleTcp(IClient client, CancellationToken cancellationToken = default)
{
if (null == client)
{
return;
}
await HandleClient(client, Defaults.ReceiveBufferSize,
(pipe) =>
{
var cipher = _remoteServerConfig.CreateCipher(_logger);
IClientFilter cipherFilter = new Cipher.TcpCipherFilter(cipher, _logger);
pipe.AddFilter(client, cipherFilter);
},
async (targetIPEndPoint) =>
{
return(await TcpClient1.ConnectAsync(targetIPEndPoint, _logger));
},
async (request, pipe, targetClient, targetSsAddr) =>
{
pipe.ClientB = targetClient;
if (request.SignificantLength > targetSsAddr.RawMemory.Length) //have some payload
{
_logger?.LogInformation($"Writing payload before piping...");
//await targetClient.WriteAsync(request.SignificantMemory.Slice(ssaddr.RawMemory.Length));
await pipe.GetWriter(targetClient).Write(request.SignificantMemory.Slice(targetSsAddr.RawMemory.Length), cancellationToken);
}
request.Dispose();
},
cancellationToken);
await Task.CompletedTask;
}
public async Task HandleTcp(IClient client, CancellationToken cancellationToken = default)
{
if (null == client)
{
return;
}
using (SmartBuffer localRequestCipher = SmartBuffer.Rent(Defaults.ReceiveBufferSize))
{
localRequestCipher.SignificantLength = await client.ReadAsync(localRequestCipher.Memory, cancellationToken);//A. Receive target addr.
//decrypt
var cipher = _remoteServerConfig.CreateCipher(_logger);
using (var localReqestPlain = cipher.DecryptTcp(localRequestCipher.SignificanMemory))
{
if (0 == localRequestCipher.SignificantLength)
{
//decrypt failed, available options: 1.leave it. 2.close connection. 3.add to blocklist.
_logger?.LogWarning($"Decrypt target addr failed, client=[{client.EndPoint.ToString()}]");
client.Close();//->local pipe broken-> local pipe close.
return;
}
IPAddress targetIP = IPAddress.Any; //TODO target address check
if (ShadowsocksAddress.TryResolve(localReqestPlain.Memory, out ShadowsocksAddress ssaddr)) //B. Resolve target addr.
{
if (0x3 == ssaddr.ATYP) //a domain name
{
var ips = await _dnsCache.ResolveHost(Encoding.UTF8.GetString(ssaddr.Address.ToArray()));
if (ips != null && ips.Length > 0)
{
targetIP = ips[0];
}
}
else//IPv4/v6
{
targetIP = new IPAddress(ssaddr.Address.Span);
}
if (IPAddress.Any == targetIP)//a empty IP.
{
_logger?.LogWarning($"Invalid target addr. client=[{client.EndPoint.ToString()}]");
client.Close();
return;
}
IPEndPoint ipeTarget = new IPEndPoint(targetIP, ssaddr.Port);
_logger.LogInformation($"Resolved target address:[{ipeTarget.ToString()}]");
_logger.LogInformation($"Connecting to [{ipeTarget.ToString()}]...");
var targetClient = await TcpClient1.ConnectAsync(ipeTarget, _logger); //C. Connect target
if (null == targetClient) //connect target failed.
{
_logger?.LogInformation($"Unable to connect target [{ipeTarget.ToString()}]. client=[{client.EndPoint.ToString()}]");
client.Close();
return;
}
_logger.LogInformation($"Connected to [{ipeTarget.ToString()}]");
if (localReqestPlain.Memory.Length > ssaddr.RawMemory.Length)//have some payload
{
_logger.LogInformation($"Writing payload before piping...");
await targetClient.WriteAsync(localReqestPlain.SignificanMemory.Slice(ssaddr.RawMemory.Length));
}
_logger.LogInformation($"Start piping...");
PipeTcp(client, targetClient, cipher, cancellationToken);//D. start piping.
}
else//invalid socks5 addr
{
_logger?.LogWarning($"StandardRemoteSocks5Handler HandleTcp resolve target addr failed. client=[{client.EndPoint.ToString()}]");
client.Close();
return;
}
}
}
await Task.CompletedTask;
}
