private static byte[] GenerateDataSubpacketFrame(
CRC32 crcCalculator, byte[] src, int offset, int chunkSize,
ZDLESequence?forceZDLESequence = null)
{
// Slice data
var dataSlice = src
.Skip(offset)
.Take(chunkSize)
.ToArray();
var encodedDataSlice = ZDLEEncoder.EscapeControlCharacters(dataSlice);
// If a ZDLESequence is forced we use that one.
// Otherweise we take ZCRCQ and if the frame is the end frame, ZCRCE.
var requiredSequence = forceZDLESequence.HasValue
? forceZDLESequence.Value
: (offset + dataSlice.Length) < src.Length
? ZDLESequence.ZCRCG
: ZDLESequence.ZCRCE;
// Create data queue for the sliced data.
var queue = new Queue <byte>(encodedDataSlice);
// Create data for checksum
var beforeCTC = dataSlice.Concat(new byte[] { (byte)requiredSequence }).ToArray();
// Compute hash
var crc = crcCalculator.ComputeHash(beforeCTC);
// Add control characters
queue.Enqueue((byte)ControlBytes.ZDLE);
queue.Enqueue((byte)requiredSequence);
var dataSubpacketFrame = queue?.ToArray();
var encodedCRC = dataSubpacketFrame
.Concat(ZDLEEncoder.EscapeControlCharacters(crc))
.ToArray();
return(encodedCRC);
}
/// <summary>
/// The sender then sends a ZFILE header with ZMODEM Conversion, Management, and Transport options[3]
/// followed by a ZCRCW data subpacket containing the file name, file length,
/// modification date, and other information identical to that used by YMODEM Batch.
/// </summary>
/// <param name="fileInfo"></param>
/// <param name="crcCalculator"></param>
private bool SendZFILEHeaderCommand(string filename, int length, DateTimeOffset lastWriteTimeUtc, CRC32 crcCalculator)
{
var result = default(bool);
var isExtended = true;
var zFileHeader = Utils.Build32BitBinHeader(
HeaderType.ZFILE,
ZFILEConversionOption.ZCBIN,
ZFILEManagementOption.ZMNEWL,
ZFILETransportOption.None,
ZFILEExtendedOptions.None,
crcCalculator
);
var zFileHeaderQueue = new Queue <byte>();
foreach (var c in zFileHeader)
{
zFileHeaderQueue.Enqueue((byte)c);
}
// Send ZFILE header first - No response
SendCommand(zFileHeaderQueue.ToArray());
var dataQueue = new Queue <byte>();
foreach (char c in filename)
{
dataQueue.Enqueue((byte)c);
}
if (isExtended)
{
dataQueue.Enqueue(0);
// File length as decimal string
var fileLength = length.ToString();
foreach (var c in fileLength)
{
dataQueue.Enqueue((byte)c);
}
// Space
dataQueue.Enqueue(0x20);
var utcTime = lastWriteTimeUtc.ToUnixTimeSeconds();
var octalString = Convert.ToString(utcTime, 8);
// Modification date
foreach (var c in octalString)
{
dataQueue.Enqueue((byte)c);
}
}
else
{
// The file information is terminated by a null.
// If only the pathname is sent, the pathname is terminated with two nulls.
dataQueue.Enqueue(0);
dataQueue.Enqueue(0);
}
byte[] data = dataQueue.Concat(new byte[] { (byte)ZDLESequence.ZCRCW }).ToArray();
dataQueue.Enqueue((byte)ControlBytes.ZDLE);
dataQueue.Enqueue((byte)ZDLESequence.ZCRCW);
var crc = crcCalculator.ComputeHash(data);
var encodedCRC = dataQueue
.Concat(ZDLEEncoder.EscapeControlCharacters(crc))
.ToArray();
var response = SendCommand(encodedCRC, true, HeaderType.ZRPOS);
// We expect ZRPOS
if (response?.ZHeader == HeaderType.ZRPOS)
{
result = true;
}
/*
* The receiver may respond with a ZSKIP header, which makes the sender
* proceed to the next file (if any) in the batch.
*
* A ZRPOS header from the receiver initiates transmission of the file
* data starting at the offset in the file specified in the ZRPOS header.
* Normally the receiver specifies the data transfer to begin begin at
* offset 0 in the file.
*/
if (response?.ZHeader == HeaderType.ZSKIP ||
response?.ZHeader == HeaderType.ZRPOS ||
response?.ZHeader == HeaderType.ZCRC)
{
/*
* The receiver has a file with the same name and length, may
* respond with a ZCRC header with a byte count, which
* requires the sender to perform a 32 bit CRC on the
* specified number of bytes in the file and transmit the
* complement of the CRC in an answering ZCRC header.the crc is
* initialised to 0xfffffff; a byte count of 0 implies the entire
* file the receiver uses this information to determine whether to
* accept the file or skip it. This sequence may be triggered
* by the ZMCRC Management Option.
*/
}
return(result);
}
