bool ReadByte_Length(byte b)
{
if (_bytesExpected == 0)
{
if ((b & 0x80) != 0)
{
_bytesExpected = (b & 0x7F) + 1;
}
else
{
_bytesExpected = 1;
}
if (_bytesExpected > 5)
{
ThrowError(104, "Number of length octets out of bounds");
}
}
_bytesRead++;
if (_bytesRead == _bytesExpected)
{
var input = new BerMemoryInput(_buffer);
if (Type == 0)
{
OuterLength = BerEncoding.DecodeLength(input);
if (OuterLength == 0)
{
ThrowError(102, "Zero outer length encountered");
}
ResetState(DecodeState.Tag);
}
else
{
Length = BerEncoding.DecodeLength(input);
var isEofOK = Length == 0;
if (IsContainer)
{
ResetState(DecodeState.Tag);
OnNewContainer();
PushContainer();
DisposeCurrentTlv();
return(isEofOK);
}
if (Length == 0)
{
OnValueReady();
}
else
{
ResetState(DecodeState.Value);
_buffer.Capacity = (int)Length;
}
return(isEofOK);
}
}
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);
}