/// <summary>
/// Decodes the specified discovery metadata packet.
/// </summary>
/// <param name="packet">The packet to decode.</param>
public static DiscoveryMetadata Decode(byte[] packet)
{
// packet contains a length and a checksum at very least
if (packet.Length < sizeof(Int32) * 2)
{
return(null);
}
// check content length
var contentLength = BitConverter.ToInt32(packet, 0);
if (packet.Length != contentLength + sizeof(Int32) * 2) // content + length + checksum
{
return(null);
}
// validate checksum
var checksum = BitConverter.ToUInt32(packet, sizeof(Int32));
var crc = new Crc32Calculator();
crc.UpdateWithBlock(packet, sizeof(Int32) * 2, contentLength);
if (checksum != crc.Crc32)
{
return(null);
}
// decode contents
var contents = packet.Skip(sizeof(Int32) * 2).ToArray();
var data = Encoding.UTF8.GetString(contents).Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries);
if (data.Length < 1)
{
return(null);
}
// extract signature and create the packet
var signature = Unescape(data.First());
var dp = CreateDiscoveryMetadata(signature);
if (dp == null)
{
return(null);
}
// populate properties
foreach (var pair in data.Skip(1))
{
var entry = pair.Split('=');
dp.Properties[Unescape(entry.First())] = Unescape(entry.Last());
}
return(dp);
}
void UpdateTop()
{
uint newHash = Crc32Calculator.Compute(description);
if (descriptionHash == newHash)
{
return;
}
descriptionHash = newHash;
panel.TextTop.SetText(description);
}
/// <summary>
/// Extracts the specified entry.
/// </summary>
/// <param name="entry">Zip file entry to extract.</param>
/// <exception cref="System.InvalidOperationException"> is thrown when the file header signature doesn't match.</exception>
public Stream Extract(Entry entry)
{
Stream outputStream = new MemoryStream();
// check file signature
Stream.Seek(entry.HeaderOffset, SeekOrigin.Begin);
if (Reader.ReadInt32() != FileSignature)
{
throw new InvalidDataException("File signature doesn't match.");
}
// move to file data
Stream.Seek(entry.DataOffset, SeekOrigin.Begin);
var inputStream = Stream;
if (entry.Deflated)
{
inputStream = new DeflateStream(Stream, CompressionMode.Decompress, true);
}
// allocate buffer, prepare for CRC32 calculation
var count = entry.OriginalSize;
var bufferSize = Math.Min(BufferSize, entry.OriginalSize);
var buffer = new byte[bufferSize];
var crc32Calculator = new Crc32Calculator();
while (count > 0)
{
// decompress data
var read = inputStream.Read(buffer, 0, bufferSize);
if (read == 0)
{
break;
}
crc32Calculator.UpdateWithBlock(buffer, read);
// copy to the output stream
outputStream.Write(buffer, 0, read);
count -= read;
}
if (crc32Calculator.Crc32 != entry.Crc32)
{
throw new InvalidDataException(string.Format(
"Corrupted archive: CRC32 doesn't match on file {0}: expected {1:x8}, got {2:x8}.",
entry.Name, entry.Crc32, crc32Calculator.Crc32));
}
return(outputStream);
}
internal uint GenerateNameIdentifier(NamedProperty namedProperty)
{
switch (namedProperty.Kind)
{
case PropertyKind.Lid:
return(namedProperty.NameIdentifier);
case PropertyKind.Name:
return(Crc32Calculator.CalculateCrc32(Encoding.Unicode.GetBytes(namedProperty.Name)));
default:
throw new NotImplementedException();
}
}
/// <summary>
/// Encodes the specified discovery metadata packet into byte array.
/// </summary>
/// <param name="dp">The packet to encode.</param>
public static byte[] Encode(DiscoveryMetadata dp)
{
// convert the packet into string
var sb = new StringBuilder();
sb.AppendFormat("{0}|", Escape(dp.Signature));
foreach (var entry in dp.Properties)
{
sb.AppendFormat("{0}={1}|", Escape(entry.Key), Escape(entry.Value));
}
// calculate checksum and merge
var content = Encoding.UTF8.GetBytes(sb.ToString());
var crc = new Crc32Calculator();
crc.UpdateWithBlock(content, 0, content.Length);
var checksum = BitConverter.GetBytes(crc.Crc32);
var contentLength = BitConverter.GetBytes(content.Length);
// packet contents: length, checksum, content
return(contentLength.Concat(checksum).Concat(content).ToArray());
}
/// <summary>
/// Extracts the specified entry.
/// </summary>
/// <param name="entry">Zip file entry to extract.</param>
/// <param name="outputStream">The stream to write the data to.</param>
/// <exception cref="System.InvalidOperationException"> is thrown when the file header signature doesn't match.</exception>
public void Extract(Entry entry, Stream outputStream)
{
// check file signature
Stream.Seek(entry.HeaderOffset, SeekOrigin.Begin);
// move to file data
Stream.Seek(entry.DataOffset, SeekOrigin.Begin);
var inputStream = Stream;
if (entry.Deflated)
{
inputStream = new DeflateStream(Stream, CompressionMode.Decompress, true);
}
// allocate buffer, prepare for CRC32 calculation
var count = entry.OriginalSize;
var bufferSize = Math.Min(BufferSize, entry.OriginalSize);
var buffer = new byte[bufferSize];
var crc32Calculator = new Crc32Calculator();
while (count > 0)
{
// decompress data
var read = inputStream.Read(buffer, 0, bufferSize);
if (read == 0)
{
break;
}
crc32Calculator.UpdateWithBlock(buffer, read);
// copy to the output stream
outputStream.Write(buffer, 0, read);
count -= read;
}
}
/// <summary>
/// Extracts the specified entry.
/// </summary>
/// <param name="entry">Zip file entry to extract.</param>
/// <param name="outputStream">The stream to write the data to.</param>
/// <exception cref="System.InvalidOperationException"> is thrown when the file header signature doesn't match.</exception>
public void Extract(Entry entry, Stream outputStream)
{
// check file signature
Stream.Seek(entry.HeaderOffset, SeekOrigin.Begin);
if (Reader.ReadInt32() != FileSignature)
{
throw new InvalidDataException("File signature doesn't match.");
}
// move to file data
Stream.Seek(entry.DataOffset, SeekOrigin.Begin);
var inputStream = Stream;
if (entry.Deflated)
{
inputStream = new DeflateStream(Stream, CompressionMode.Decompress, true);
}
// allocate buffer, prepare for CRC32 calculation
var count = entry.OriginalSize;
var bufferSize = Math.Min(BufferSize, entry.OriginalSize);
var buffer = new byte[bufferSize];
var crc32Calculator = new Crc32Calculator();
while (count > 0)
{
// decompress data
var read = inputStream.Read(buffer, 0, bufferSize);
if (read == 0)
{
break;
}
crc32Calculator.UpdateWithBlock(buffer, read);
// copy to the output stream
outputStream.Write(buffer, 0, read);
count -= read;
}
if (crc32Calculator.Crc32 != entry.Crc32)
{
throw new InvalidDataException(string.Format(
"Corrupted archive: CRC32 doesn't match on file {0}: expected {1:x8}, got {2:x8}.",
entry.Name, entry.Crc32, crc32Calculator.Crc32));
}
}
