/// <summary>
/// Produces a data socket using Passive (PASV) or Extended Passive (EPSV) mode
/// </summary>
/// <returns></returns>
internal async Task <Stream> ConnectDataStreamAsync()
{
Logger?.LogTrace("[FtpClient] Connecting to a data socket");
var epsvResult = await ControlStream.SendCommandAsync(FtpCommand.EPSV);
int?passivePortNumber;
if (epsvResult.FtpStatusCode == FtpStatusCode.EnteringExtendedPassive)
{
passivePortNumber = epsvResult.ResponseMessage.ExtractEpsvPortNumber();
}
else
{
// EPSV failed - try regular PASV
var pasvResult = await ControlStream.SendCommandAsync(FtpCommand.PASV);
if (pasvResult.FtpStatusCode != FtpStatusCode.EnteringPassive)
{
throw new FtpException(pasvResult.ResponseMessage);
}
passivePortNumber = pasvResult.ResponseMessage.ExtractPasvPortNumber();
}
if (!passivePortNumber.HasValue)
{
throw new FtpException("Could not determine EPSV/PASV data port");
}
return(await ControlStream.OpenDataStreamAsync(Configuration.Host, passivePortNumber.Value, CancellationToken.None));
}