pub fn extract_fragment(raw: &[u8]) -> Option<FragmentHeader>Expand description
Lightweight fragment extraction from an LpPacket.
Scans the TLV fields for Sequence, FragIndex, FragCount, and Fragment
without creating Bytes sub-slices, parsing Nack headers, or allocating.
Returns Some only if the packet is a multi-fragment LpPacket (frag_count > 1).
This is the hot-path parser for the fragment sieve — unfragmented LpPackets,
Nacks, and bare Interest/Data fall through to the full LpPacket::decode.