public static async Task <Command> ReadFromAsync(IReadOnlyStream stream, ArrayPool <byte> bufferPool)
{
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
if (bufferPool == null)
{
throw new ArgumentNullException(nameof(bufferPool));
}
// | VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
// | 1 | 1 | X'00' | 1 | Variable | 2 |
var buffer = bufferPool.Rent(byte.MaxValue + sizeof(ushort));
try
{
await stream.ReadExactlyAsync(buffer, 0, 4).ConfigureAwait(false);
if (buffer[0] != 5)
{
throw new InvalidDataException($"Invalid SOCKS version in greeting: {buffer[0]}");
}
var commandType = (CommandType)buffer[1];
if (commandType != CommandType.Bind &&
commandType != CommandType.Connect &&
commandType != CommandType.UdpAssociate)
{
throw new ProtocolException(
$"Invalid command type: {commandType}",
CommandReplyType.CommandNotSupported);
}
if (buffer[2] != 0)
{
throw new InvalidDataException("Invalid command.");
}
var addressType = (AddressType)buffer[3];
var endPoint = stream.ReadEndPoint(addressType, bufferPool);
return(new Command(commandType, endPoint));
}
finally
{
bufferPool.Return(buffer);
}
}