bacnet-npdu

The BACnet network-layer vocabulary from Clause 6 of ASHRAE 135, for rusty-bacnet: one definition of each concept, shared by the portable cores (bacnet-mstp-core, bacnet-bip-core, bacnet-router-core), the hosted transports and network layer, and the owned NPDU codec of bacnet-encoding.

• #![no_std], no allocator, no dependencies.
• Npdu: a borrowed view of an NPDU's control information and payload. Npdu::decode reads one in place and reports an address too long for any data link apart from every other fault, with what a router needs to address its reject; Npdu::encoded_len and Npdu::encode_into write one into your buffer, refusing anything the decoder refuses before writing an octet.
• NetworkMessageType and RejectMessageReason: open sets of wire codes with named constants. Any octet converts, so a match on them needs a wildcard arm.
• RejectMessageToNetwork: a reject's reason and network, read and written in place; RejectLengthError refuses data that isn't three octets.
• NetworkPriority: the closed, two-bit network priority.
• NpduLimits and MAX_NPDU (1,497 octets): the longest NPDU a link carries each way.
• Mac and MAX_MAC_LEN (18 octets): a link-layer address stored inline.

Example

use bacnet_npdu::{Address, NetworkMessageType, Npdu};

// What-Is-Network-Number, for the local network.
let question = Npdu::message(NetworkMessageType::WHAT_IS_NETWORK_NUMBER, &[]);
let mut frame = [0u8; 8];
let len = question.encode_into(&mut frame)?;
assert_eq!(&frame[..len], &[0x01, 0x80, 0x12]);

// A routed APDU, read in place.
let routed = [0x01, 0x20, 0x00, 0x02, 0x01, 0x05, 0xFF, 0x10, 0x08];
let npdu = Npdu::decode(&routed).expect("an NPDU");
assert_eq!(npdu.destination, Some(Address { network: 2, mac: &[5] }));
assert_eq!(npdu.payload, &[0x10, 0x08]);
assert!(!npdu.is_network_message());
# Ok::<(), Box<dyn core::error::Error>>(())

License

MIT