bool ReadByte_Tag(byte b)
{
if (b == 0 && _bytesRead == 0)
{
ResetState(DecodeState.Terminator);
return(false);
}
if (_bytesRead > 12)
{
ThrowError(103, "Number of tag octets out of bounds");
}
if (_bytesRead == 0 && (b & 0x1F) != 0x1F ||
_bytesRead > 0 && (b & 0x80) == 0)
{
var input = new BerMemoryInput(_buffer);
if (Tag.IsZero)
{
// no outer tag read yet -> read outer tag
var tag = BerEncoding.DecodeTag(input);
if (tag.Class == BerClass.Universal)
{
ThrowError(107, "Universal outer tag encountered");
}
if (tag.IsContainer == false)
{
ThrowError(108, "Primitive outer tag encountered");
}
Tag = tag.ToPrimitive(); // clear container flag
}
else
{
// outer tag already read -> read inner tag (type tag)
var typeTag = BerEncoding.DecodeTag(input);
var type = typeTag.NumberAsType;
if (BerType.IsApplicationDefined(type) == false)
{
if (typeTag.Class != BerClass.Universal)
{
ThrowError(110, "Non-universal inner tag encountered");
}
if (type == 0 || type >= BerType.LastUniversal)
{
ThrowError(109, "Invalid BER type encountered");
}
}
IsContainer = typeTag.IsContainer;
Type = type;
}
ResetState(DecodeState.Length);
return(false);
}
_bytesRead++;
return(false);
}
/// <summary>
/// Read the next TLTLV and publishes information like <see cref="BerLib.BerReaderBase.Tag" />,
/// <see cref="BerLib.BerReaderBase.Length" />, <see cref="BerLib.BerReaderBase.Type" /> and
/// <see cref="BerLib.BerReaderBase.IsContainer" />.
/// Use one of the Get() functions of BerLib.BerReaderBase to retrieve the Value.
/// </summary>
/// <returns>True if a valid TLTLV has been read, otherwise false.</returns>
public bool Read()
{
Debug.Assert(_input != null);
var typeTag = BerTag.Zero;
DisposeCurrentTlv();
if (_parentReader != null && // non top-level read?
this.Eof)
{
HandleEof();
return(false);
}
Tag = BerEncoding.DecodeTag(this);
if (Tag.IsZero)
{
// terminator of indefinite length field: 4 zeros (outer length AND inner length must be indefinite
if (ReadByte() == 0 &&
ReadByte() == 0 &&
ReadByte() == 0)
{
HandleEof();
return(false);
}
else
{
ThrowError(10, "Invalid zero tag: 0x00");
}
}
OuterLength = BerEncoding.DecodeLength(this);
if (OuterLength == 0)
{
ThrowError(13, "Zero outer length encountered");
}
if (Tag.IsContainer &&
Tag.Class != BerClass.Universal)
{
typeTag = BerEncoding.DecodeTag(this);
Length = BerEncoding.DecodeLength(this);
if ((Length == BerDefinitions.IndefiniteLength) != (OuterLength == BerDefinitions.IndefiniteLength))
{
ThrowError(12, "Outer and inner tag must use the same length form");
}
}
else
{
ThrowError(14, "Implicit tag or universal outer tag found");
}
IsContainer = typeTag.IsContainer;
Tag = Tag.ToPrimitive(); // clear container flag
Type = typeTag.NumberAsType;
if (Length == BerDefinitions.IndefiniteLength &&
IsContainer == false)
{
ThrowError(11, "Indefinite length form is only allowed on containers");
}
if (IsContainer == false &&
Length > 0)
{
var value = new byte[Length];
for (int index = 0; index < Length; index++)
{
value[index] = ReadByte();
}
Value = value;
}
return(true);
}