public int?ReadStartArray()
{
CborInitialByte header = PeekInitialByte(expectedType: CborMajorType.Array);
if (header.AdditionalInfo == CborAdditionalInfo.IndefiniteLength)
{
if (_isConformanceLevelCheckEnabled && CborConformanceLevelHelpers.RequiresDefiniteLengthItems(ConformanceLevel))
{
throw new FormatException("Indefinite-length items are not supported under the current conformance level.");
}
AdvanceBuffer(1);
PushDataItem(CborMajorType.Array, null);
return(null);
}
else
{
ulong arrayLength = ReadUnsignedInteger(_buffer.Span, header, out int additionalBytes);
if (arrayLength > (ulong)_buffer.Length)
{
throw new FormatException("Insufficient buffer size for declared definite length in CBOR data item.");
}
AdvanceBuffer(1 + additionalBytes);
PushDataItem(CborMajorType.Array, (int)arrayLength);
return((int)arrayLength);
}
}
public void WriteTag(CborTag tag)
{
if (!CborConformanceLevelHelpers.AllowsTags(ConformanceLevel))
{
throw new InvalidOperationException("Tagged items are not permitted under the current conformance level.");
}
WriteUnsignedInteger(CborMajorType.Tag, (ulong)tag);
_isTagContext = true;
}
public CborTag ReadTag()
{
CborTag tag = PeekTagCore(out int additionalBytes);
if (_isConformanceLevelCheckEnabled && !CborConformanceLevelHelpers.AllowsTags(ConformanceLevel))
{
throw new FormatException("Tagged items are not permitted under the current conformance level.");
}
AdvanceBuffer(1 + additionalBytes);
_isTagContext = true;
return(tag);
}
public void ReadTag(CborTag expectedTag)
{
CborTag tag = PeekTagCore(out int additionalBytes);
if (_isConformanceLevelCheckEnabled && !CborConformanceLevelHelpers.AllowsTags(ConformanceLevel))
{
throw new FormatException("Tagged items are not permitted under the current conformance level.");
}
if (expectedTag != tag)
{
throw new InvalidOperationException("CBOR tag mismatch.");
}
AdvanceBuffer(1 + additionalBytes);
_isTagContext = true;
}
// Unsigned integer decoding https://tools.ietf.org/html/rfc7049#section-2.1
private ulong ReadUnsignedInteger(ReadOnlySpan <byte> buffer, CborInitialByte header, out int additionalBytes)
{
ulong result;
switch (header.AdditionalInfo)
{
case CborAdditionalInfo x when(x < CborAdditionalInfo.Additional8BitData):
additionalBytes = 0;
return((ulong)x);
case CborAdditionalInfo.Additional8BitData:
EnsureBuffer(buffer, 2);
result = buffer[1];
if (result < (int)CborAdditionalInfo.Additional8BitData)
{
ValidateIsNonStandardIntegerRepresentationSupported();
}
additionalBytes = 1;
return(result);
case CborAdditionalInfo.Additional16BitData:
EnsureBuffer(buffer, 3);
result = BinaryPrimitives.ReadUInt16BigEndian(buffer.Slice(1));
if (result <= byte.MaxValue)
{
ValidateIsNonStandardIntegerRepresentationSupported();
}
additionalBytes = 2;
return(result);
case CborAdditionalInfo.Additional32BitData:
EnsureBuffer(buffer, 5);
result = BinaryPrimitives.ReadUInt32BigEndian(buffer.Slice(1));
if (result <= ushort.MaxValue)
{
ValidateIsNonStandardIntegerRepresentationSupported();
}
additionalBytes = 4;
return(result);
case CborAdditionalInfo.Additional64BitData:
EnsureBuffer(buffer, 9);
result = BinaryPrimitives.ReadUInt64BigEndian(buffer.Slice(1));
if (result <= uint.MaxValue)
{
ValidateIsNonStandardIntegerRepresentationSupported();
}
additionalBytes = 8;
return(result);
default:
throw new FormatException("initial byte contains invalid integer encoding data.");
}
void ValidateIsNonStandardIntegerRepresentationSupported()
{
if (_isConformanceLevelCheckEnabled && CborConformanceLevelHelpers.RequiresMinimalIntegerRepresentation(ConformanceLevel))
{
throw new FormatException("Non-minimal integer representations are not permitted under the current conformance level.");
}
}
}