public ICollection <ArraySegment <byte> > ReadLabels()
{
var result = new List <ArraySegment <byte> >(10);
// read the length byte for the label, then get the content from offset+1 to length
// proceed till we reach zero length byte.
byte length;
while ((length = ReadByte()) != 0)
{
// respect the reference bit and lookup the name at the given position
// the reader will advance only for the 2 bytes read.
if ((length & ReferenceByte) != 0)
{
int subIndex = (length & 0x3f) << 8 | ReadByte();
if (subIndex >= _data.Array.Length - 1)
{
// invalid length pointer, seems to be actual length of a label which exceeds 63 chars...
// get back one and continue other labels
_index--;
result.Add(_data.SubArray(_index, length));
Advance(length);
continue;
}
var subReader = new DnsDatagramReader(_data.SubArrayFromOriginal(subIndex));
var newLabels = subReader.ReadLabels();
result.AddRange(newLabels); // add range actually much faster than concat and equal to or faster than for-each.. (array copy would work maybe)
return(result);
}
if (_index + length >= _count)
{
throw new DnsResponseParseException(
"Found invalid label position.", _data.ToArray(), _index, length);
}
var label = _data.SubArray(_index, length);
// maybe store original bytes in this instance too?
result.Add(label);
Advance(length);
}
return(result);
}