private static bool VerifyChecksum(byte[] raw, XISFChecksumTypeEnum cksumType, string providedCksum)
{
string computedCksum;
SHA3Managed sha3;
using (MyStopWatch.Measure($"XISF Checksum = {cksumType}")) {
switch (cksumType)
{
case XISFChecksumTypeEnum.SHA1:
SHA1 sha1 = new SHA1CryptoServiceProvider();
computedCksum = GetStringFromHash(sha1.ComputeHash(raw));
sha1.Dispose();
break;
case XISFChecksumTypeEnum.SHA256:
SHA256 sha256 = new SHA256CryptoServiceProvider();
computedCksum = GetStringFromHash(sha256.ComputeHash(raw));
sha256.Dispose();
break;
case XISFChecksumTypeEnum.SHA512:
SHA512 sha512 = new SHA512CryptoServiceProvider();
computedCksum = GetStringFromHash(sha512.ComputeHash(raw));
sha512.Dispose();
break;
case XISFChecksumTypeEnum.SHA3_256:
sha3 = new SHA3Managed(256);
computedCksum = GetStringFromHash(sha3.ComputeHash(raw));
sha3.Dispose();
break;
case XISFChecksumTypeEnum.SHA3_512:
sha3 = new SHA3Managed(512);
computedCksum = GetStringFromHash(sha3.ComputeHash(raw));
sha3.Dispose();
break;
default:
return(false);
}
}
if (computedCksum.Equals(providedCksum))
{
return(true);
}
else
{
Logger.Error($"XISF: Invalid data block checksum! Expected: {providedCksum} Got: {computedCksum}");
return(false);
}
}
public static async Task <ImageData> Load(Uri filePath, bool isBayered)
{
using (FileStream fs = new FileStream(filePath.LocalPath, FileMode.Open)) {
// First make sure we are opening a XISF file by looking for the XISF signature at bytes 1-8
byte[] fileSig = new byte[xisfSignature.Length];
fs.Read(fileSig, 0, fileSig.Length);
if (!fileSig.SequenceEqual(xisfSignature))
{
Logger.Error($"XISF: Opened file \"{filePath.LocalPath}\" is not a valid XISF file");
throw new InvalidDataException(Locale.Loc.Instance["LblXisfInvalidFile"]);
}
Logger.Debug($"XISF: Opening file \"{filePath.LocalPath}\"");
// Get the header length info, bytes 9-12
byte[] headerLengthInfo = new byte[4];
fs.Read(headerLengthInfo, 0, headerLengthInfo.Length);
uint headerLength = BitConverter.ToUInt32(headerLengthInfo, 0);
// Skip the next 4 bytes as they are reserved space
fs.Seek(4, SeekOrigin.Current);
// XML document starts at byte 17
byte[] bytes = new byte[headerLength];
fs.Read(bytes, 0, (int)headerLength);
string xmlString = Encoding.UTF8.GetString(bytes);
/*
* Create the header for ease of access
*/
XElement xml = XElement.Parse(xmlString);
var header = new XISFHeader(xml);
var metaData = new ImageMetaData();
try {
metaData = header.ExtractMetaData();
} catch (Exception ex) {
Logger.Error($"XISF: Error during metadata extraction {ex.Message}");
}
/*
* Retrieve the geometry attribute.
*/
int width = 0;
int height = 0;
try {
string[] geometry = header.Image.Attribute("geometry").Value.Split(':');
width = int.Parse(geometry[0]);
height = int.Parse(geometry[1]);
} catch (Exception ex) {
Logger.Error($"XISF: Could not find image geometry: {ex}");
throw new InvalidDataException(Locale.Loc.Instance["LblXisfInvalidGeometry"]);
}
Logger.Debug($"XISF: File geometry: width={width}, height={height}");
/*
* Retrieve the pixel data type
*/
string sampleFormat = "UInt16";
try {
sampleFormat = header.Image.Attribute("sampleFormat").Value.ToString();
} catch (InvalidDataException ex) {
Logger.Error($"XISF: Could not read image data: {ex}");
throw ex;
} catch (Exception ex) {
Logger.Error($"XISF: Could not find image data type: {ex}");
throw new InvalidDataException("Could not find XISF image data type");
}
/*
* Determine if the data block is compressed and if a checksum is provided for it
*/
XISFCompressionInfo compressionInfo = new XISFCompressionInfo();
string[] compression = null;
try {
if (header.Image.Attribute("compression") != null)
{
// [compression codec]:[uncompressed size]:[sizeof shuffled typedef]
compression = header.Image.Attribute("compression").Value.ToLower().Split(':');
if (!string.IsNullOrEmpty(compression[0]))
{
compressionInfo = GetCompressionType(compression);
}
}
else
{
Logger.Debug("XISF: Compressed data block was not encountered");
}
} catch (InvalidDataException) {
Logger.Error($"XISF: Unknown compression codec encountered: {compression[0]}");
throw new InvalidDataException(string.Format(Locale.Loc.Instance["LblXisfUnsupportedCompression"], compression[0]));
}
if (compressionInfo.CompressionType != XISFCompressionTypeEnum.NONE)
{
Logger.Debug(string.Format("XISF: CompressionType: {0}, UncompressedSize: {1}, IsShuffled: {2}, ItemSize: {3}",
compressionInfo.CompressionType,
compressionInfo.UncompressedSize,
compressionInfo.IsShuffled,
compressionInfo.ItemSize));
}
/*
* Determine if a checksum is provided for the datablock.
* If the data block is compressed, the checksum is for the compressed form.
*/
XISFChecksumTypeEnum cksumType = XISFChecksumTypeEnum.NONE;
string cksumHash = string.Empty;
string[] cksum = null;
try {
if (header.Image.Attribute("checksum") != null)
{
// [hash type]:[hash string]
cksum = header.Image.Attribute("checksum").Value.ToLower().Split(':');
if (!string.IsNullOrEmpty(cksum[0]))
{
cksumType = GetChecksumType(cksum[0]);
cksumHash = cksum[1];
}
}
else
{
Logger.Debug("XISF: Checksummed data block was not encountered");
}
} catch (InvalidDataException) {
Logger.Error($"XISF: Unknown checksum type: {cksum[0]}");
throw new InvalidDataException(string.Format(Locale.Loc.Instance["LblXisfUnsupportedChecksum"], cksum[0]));
}
if (cksumType != XISFChecksumTypeEnum.NONE)
{
Logger.Debug($"XISF: Checksum type: {cksumType}, Hash: {cksumHash}");
}
/*
* Retrieve the attachment attribute to find the start and length of the data block.
* If the attachment attribute does not exist, we assume that the image data is
* inside a <Data> element and is base64-encoded.
*/
ImageData imageData;
if (header.Image.Attribute("location").Value.StartsWith("attachment"))
{
string[] location = header.Image.Attribute("location").Value.Split(':');
int start = int.Parse(location[1]);
int size = int.Parse(location[2]);
Logger.Debug($"XISF: Data block type: attachment, Data block start: {start}, Data block size: {size}");
// Read the data block in, starting at the specified offset
byte[] raw = new byte[size];
fs.Seek(start, SeekOrigin.Begin);
fs.Read(raw, 0, size);
// Validate the data block's checksum
if (cksumType != XISFChecksumTypeEnum.NONE)
{
if (!VerifyChecksum(raw, cksumType, cksumHash))
{
// Only emit a warning to the user about a bad checksum for now
Notification.Notification.ShowWarning(Locale.Loc.Instance["LblXisfBadChecksum"]);
}
}
// Uncompress the data block
if (compressionInfo.CompressionType != XISFCompressionTypeEnum.NONE)
{
raw = UncompressData(raw, compressionInfo);
if (compressionInfo.IsShuffled)
{
raw = XISFData.Unshuffle(raw, compressionInfo.ItemSize);
}
}
var converter = GetConverter(sampleFormat);
var img = converter.Convert(raw);
imageData = new ImageData(img, width, height, 16, isBayered, metaData);
}
else
{
string base64Img = header.Image.Element("Data").Value;
byte[] encodedImg = Convert.FromBase64String(base64Img);
var converter = GetConverter(sampleFormat);
var img = converter.Convert(encodedImg);
imageData = new ImageData(img, width, height, 16, isBayered, metaData);
}
return(imageData);
}
}
