bacnet_network/
network_number.rs

1//! Shared packet contract for the two local nonrouter Network Number controls.
2use crate::layer::ReceivedNetworkControl;
3use bacnet_types::{enums::NetworkMessageType, network_number::NetworkNumber};
4use std::sync::atomic::{AtomicU16, Ordering};
5use std::sync::Arc;
6
7/// A validated local control, independent of transport and configured authority.
8#[derive(Clone, Copy, Debug, PartialEq, Eq)]
9pub enum NumberControl {
10    /// A local query received by unicast or logical broadcast.
11    WhatIs,
12    /// A valid logical-broadcast announcement.
13    NumberIs {
14        /// Peer-reported number, in 1..=65534.
15        number: u16,
16        /// Peer-reported configured flag, zero or one.
17        flag: u8,
18    },
19}
20impl NumberControl {
21    /// Refuse routed, malformed or ineligible controls without changing state.
22    pub fn parse(control: &ReceivedNetworkControl) -> Option<Self> {
23        let npdu = &control.npdu;
24        if !npdu.is_network_message || npdu.source.is_some() || npdu.destination.is_some() {
25            return None;
26        }
27        match npdu.message_type {
28            Some(t)
29                if t == NetworkMessageType::WHAT_IS_NETWORK_NUMBER.to_raw()
30                    && npdu.payload.is_empty() =>
31            {
32                Some(Self::WhatIs)
33            }
34            Some(t)
35                if t == NetworkMessageType::NETWORK_NUMBER_IS.to_raw()
36                    && control.link_layer_group
37                    && npdu.payload.len() == 3 =>
38            {
39                let number = u16::from_be_bytes([npdu.payload[0], npdu.payload[1]]);
40                let flag = npdu.payload[2];
41                (number != 0 && number != u16::MAX && flag <= 1)
42                    .then_some(Self::NumberIs { number, flag })
43            }
44            _ => None,
45        }
46    }
47}
48
49/// Encode a known number as a complete local-broadcast control NPDU.
50/// Learned-configured state still transmits flag zero; unknown has no reply.
51pub fn number_is_reply(state: NetworkNumber) -> Option<[u8; 6]> {
52    let (number, quality) = state.snapshot();
53    (number != 0).then_some([
54        1,
55        0x80,
56        NetworkMessageType::NETWORK_NUMBER_IS.to_raw(),
57        (number >> 8) as u8,
58        number as u8,
59        u8::from(quality == 3),
60    ])
61}
62
63/// The number of the network a single-port node is attached to, shared
64/// between the task that owns its Number controls and the senders that read
65/// it. Each [`NetworkLayer`](crate::layer::NetworkLayer) holds one
66/// ([`NetworkLayer::local_network_number`](crate::layer::NetworkLayer::local_network_number)),
67/// and clones share one value. Reading or publishing takes no lock.
68///
69/// It starts unknown. The layer never learns a number by itself: the owner of
70/// its Number controls publishes the state it holds whenever an announcement
71/// may have changed it, and a registered Network Port's owner also publishes
72/// the port's number at startup. The value is a copy of that state, never a
73/// second authority.
74#[derive(Clone, Debug, Default)]
75pub struct LocalNetworkNumber(Arc<AtomicU16>);
76
77impl LocalNetworkNumber {
78    /// Record the number `state` holds. An unknown state records unknown;
79    /// a known number is always in 1..=65534.
80    pub fn publish(&self, state: NetworkNumber) {
81        self.0.store(state.snapshot().0, Ordering::Release);
82    }
83
84    /// The last number published, or `None` while it is unknown.
85    pub fn get(&self) -> Option<u16> {
86        match self.0.load(Ordering::Acquire) {
87            0 => None,
88            number => Some(number),
89        }
90    }
91}
92
93#[cfg(test)]
94mod tests;
bacnet_network/network_number.rs

bacnet_network/
network_number.rs
