Struct BvllFrame 

pub struct BvllFrame<'a> {
    pub function: BvlcFunction,
    pub payload: &'a [u8],
}

A BVLL message whose header checks out, before its payload is read.

BvllFrame::decode checks the BVLC type and the Length field and accepts any function code, so a receiver can see a function it doesn’t know, or decide how to answer a request whose payload is malformed, before BvllFrame::message reads the payload by the function’s layout.

Fields

function: BvlcFunction

The function octet.

payload: &'a [u8]

The octets after the 4-octet header.

Implementations

impl<'a> BvllFrame<'a>

pub fn decode(datagram: &'a [u8]) -> Result<Self, BvllError>

Check a datagram’s BVLL header and split off its payload.

The datagram must be one whole message: at least the 4-octet header, BVLC type 0x81, and a Length field equal to the datagram’s length, since it counts the whole message (Annex J.2). Octets after the declared length are refused rather than ignored, so a datagram can’t pass for a shorter message.

use bacnet_bip_codec::{BvlcFunction, BvllError, BvllFrame};

// A Read-Foreign-Device-Table: header only.
let frame = BvllFrame::decode(&[0x81, 0x06, 0x00, 0x04])?;
assert_eq!(frame.function, BvlcFunction::READ_FOREIGN_DEVICE_TABLE);
assert!(frame.payload.is_empty());

// An unknown function still has a frame, but no message.
let frame = BvllFrame::decode(&[0x81, 0x0C, 0x00, 0x05, 0xAA])?;
assert_eq!(frame.message(), Err(BvllError::UnknownFunction { function: 0x0C }));

// A trailing octet the Length field doesn't count.
assert_eq!(
    BvllFrame::decode(&[0x81, 0x06, 0x00, 0x04, 0x00]),
    Err(BvllError::LengthMismatch { declared: 4, received: 5 }),
);

pub fn message(self) -> Result<Bvll<'a>, BvllError>

Read the payload by the function’s layout (see BvlcFunction::payload_shape).

Fails with BvllError::UnknownFunction for a function Annex J doesn’t define, and with BvllError::PayloadLength when the payload is the wrong length for its function. Field values are not judged: an undefined result code, a zero time-to-live, any mask or address, and an empty NPDU all decode.

Trait Implementations

impl<'a> Clone for BvllFrame<'a>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Copy for BvllFrame<'a>

impl<'a> Debug for BvllFrame<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> Eq for BvllFrame<'a>

impl<'a> PartialEq for BvllFrame<'a>

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<'a> StructuralPartialEq for BvllFrame<'a>