private void InternalDownload(IChannel channel, Stream input, Stream output, string filename, long length)
{
var buffer = new byte[Math.Min(length, BufferSize)];
var needToRead = length;
do
{
var read = input.Read(buffer, 0, (int) Math.Min(needToRead, BufferSize));
output.Write(buffer, 0, read);
RaiseDownloadingEvent(filename, length, length - needToRead);
needToRead -= read;
}
while (needToRead > 0);
output.Flush();
// Raise one more time when file downloaded
RaiseDownloadingEvent(filename, length, length - needToRead);
// Send confirmation byte after last data byte was read
SendConfirmation(channel);
CheckReturnCode(input);
}