ule

ULE — Unidirectional Lightweight Encapsulation (RFC 4326) with Extension Headers (RFC 5163): IP (and other PDUs) over MPEG-2 Transport Streams.

Implements:

• Sndu — the SubNetwork Data Unit wire structure (RFC 4326 §4): the D bit + 15-bit Length + 16-bit Type, an optional 6-byte Destination NPA address (present iff D = 0), the PDU, and the 4-byte CRC-32 trailer. Length and the CRC are recomputed on serialize from the typed fields.
• TypeField — the §4.4 split at 0x0600: a Next-Header (H-LEN/H-Type) below, an EtherType at or above.
• ExtensionHeader / PayloadChain — chained extension headers (RFC 4326 §5, RFC 5163 §3): Optional headers (H-LEN = 1..=5, total 2·H-LEN bytes) terminated by an EtherType or a Mandatory header (Test-SNDU 0x00, Bridged-Frame 0x01, TS-Concat 0x02, PDU-Concat 0x03).
• UleReceiver — TS-packet de-fragmentation/reassembly (RFC 4326 §6, §7): PUSI + 1-byte Payload Pointer handling, fragmentation across packets, packing of multiple SNDUs per packet, and End-Indicator / 0xFF padding.

The CRC-32 is the MPEG-2 / DSM-CC CRC (poly 0x04C11DB7, init 0xFFFFFFFF, MSB-first, no reflection, no final XOR — RFC 4326 §4.6), reused from dvb-common. It is verified byte-exact against RFC 4326 Appendix B's worked example (CRC 0x7C171763) in the crate's fixture test.

#![no_std] + alloc; depends only on dvb-common.

Quick start

use ule::{Sndu, TypeField};

let pdu = [0x45u8, 0x00, 0x00, 0x14]; // start of an IPv4 header
let sndu = Sndu::new(
    TypeField::EtherType(0x0800),
    Some([0x00, 0x01, 0x02, 0x03, 0x04, 0x05]),
    &pdu,
);
let mut buf = vec![0u8; sndu.serialized_len()];
sndu.serialize_into(&mut buf).unwrap();
assert_eq!(Sndu::parse(&buf).unwrap(), sndu);

Examples

cargo run -p ule --example build_sndu
cargo run -p ule --example receive_sndu

Features

Minimum Supported Rust Version

1.81

License

MIT OR Apache-2.0