bacnet_encoding/constructed/
log_multiple_record.rs

1//! Trend Log Multiple log records (Clause 12.30.19), framed as Clause 21
2//! gives BACnetLogMultipleRecord.
3//!
4//! A record is two constructed fields. Context tag 0 wraps the timestamp, an
5//! application Date then an application Time. Context tag 1 wraps the log
6//! data, one of three alternatives: a primitive context 0 holding the
7//! three-bit log status, a constructed context 1 holding one entry per
8//! logged member, or a primitive context 2 holding the clock change as a
9//! REAL. Inside the member list each entry has its own context tag, 0 to 8
10//! in [`LogValue`] declaration order: the seven plain datatypes as
11//! primitives, then failure as a constructed pair of application
12//! Enumerated class and code, then any-value as a constructed wrapper
13//! around the value's own tagged encoding.
14
15use super::log_fields::{
16    check_bit_string, decode_any_value, decode_failure, decode_integer, decode_log_status,
17    decode_timestamp, encode_any_value, encode_ctx_integer, encode_failure, encode_log_status,
18    encode_timestamp,
19};
20use super::tagged::{contents, decode_ctx_constructed, expect_end};
21use crate::{primitives, tags};
22use bacnet_types::constructed::{BACnetLogMultipleRecord, LogData, LogValue};
23use bacnet_types::error::Error;
24use bytes::BytesMut;
25
26const RECORD: &str = "BACnetLogMultipleRecord";
27const TIMESTAMP: &str = "BACnetLogMultipleRecord timestamp";
28const LOG_DATA: &str = "BACnetLogMultipleRecord log-data";
29const FAILURE_FIELD: &str = "BACnetLogMultipleRecord failure";
30
31const BOOLEAN: u8 = 0;
32const REAL: u8 = 1;
33const ENUMERATED: u8 = 2;
34const UNSIGNED: u8 = 3;
35const INTEGER: u8 = 4;
36const BIT_STRING: u8 = 5;
37const NULL: u8 = 6;
38const FAILURE: u8 = 7;
39const ANY: u8 = 8;
40
41/// Encode one Trend Log Multiple record.
42///
43/// Fails, leaving `buf` unchanged, for a bit string whose unused-bit count
44/// is above 7 (or nonzero with no data) or an any-value whose bytes aren't
45/// complete tagged values.
46pub fn encode_log_multiple_record(
47    record: &BACnetLogMultipleRecord,
48    buf: &mut BytesMut,
49) -> Result<(), Error> {
50    let mut out = BytesMut::new();
51    encode_timestamp(&mut out, &record.date, &record.time);
52    tags::encode_opening_tag(&mut out, 1);
53    match &record.log_data {
54        LogData::LogStatus(status) => encode_log_status(&mut out, 0, *status),
55        LogData::Values(values) => {
56            tags::encode_opening_tag(&mut out, 1);
57            for value in values {
58                encode_value(value, &mut out)?;
59            }
60            tags::encode_closing_tag(&mut out, 1);
61        }
62        LogData::TimeChange(seconds) => primitives::encode_ctx_real(&mut out, 2, *seconds),
63    }
64    tags::encode_closing_tag(&mut out, 1);
65    buf.extend_from_slice(&out);
66    Ok(())
67}
68
69fn encode_value(value: &LogValue, buf: &mut BytesMut) -> Result<(), Error> {
70    match value {
71        LogValue::BooleanValue(value) => primitives::encode_ctx_boolean(buf, BOOLEAN, *value),
72        LogValue::RealValue(value) => primitives::encode_ctx_real(buf, REAL, *value),
73        LogValue::EnumValue(value) => primitives::encode_ctx_unsigned(buf, ENUMERATED, *value),
74        LogValue::UnsignedValue(value) => primitives::encode_ctx_unsigned(buf, UNSIGNED, *value),
75        LogValue::SignedValue(value) => encode_ctx_integer(buf, INTEGER, *value),
76        LogValue::BitstringValue { unused_bits, data } => {
77            check_bit_string(*unused_bits, data, "bitstring-value")?;
78            primitives::encode_ctx_bit_string(buf, BIT_STRING, *unused_bits, data);
79        }
80        LogValue::NullValue => tags::encode_tag(buf, NULL, tags::TagClass::Context, 0),
81        LogValue::Failure {
82            error_class,
83            error_code,
84        } => encode_failure(buf, FAILURE, *error_class, *error_code),
85        LogValue::AnyValue(bytes) => encode_any_value(buf, ANY, bytes)?,
86    }
87    Ok(())
88}
89
90/// Decode one Trend Log Multiple record starting at `offset`, returning it
91/// and the offset just past it.
92pub fn decode_log_multiple_record(
93    data: &[u8],
94    offset: usize,
95) -> Result<(BACnetLogMultipleRecord, usize), Error> {
96    let (date, time, data_start) = decode_timestamp(data, offset, TIMESTAMP)?;
97    let (body, end) = decode_ctx_constructed(data, data_start, 1, LOG_DATA)?;
98    let log_data = decode_log_data(body, data_start)?;
99    Ok((
100        BACnetLogMultipleRecord {
101            date,
102            time,
103            log_data,
104        },
105        end,
106    ))
107}
108
109fn decode_log_data(data: &[u8], offset: usize) -> Result<LogData, Error> {
110    let (tag, start) = tags::decode_tag(data, 0)?;
111    let (log_data, end) = if tag.is_context(0) {
112        let (octets, end) = contents(data, start, tag.length)?;
113        (
114            LogData::LogStatus(decode_log_status(octets, offset, RECORD)?),
115            end,
116        )
117    } else if tag.is_opening_tag(1) {
118        let (list, end) = tags::extract_context_value(data, start, 1)?;
119        (LogData::Values(decode_values(list, offset)?), end)
120    } else if tag.is_context(2) {
121        let (octets, end) = contents(data, start, tag.length)?;
122        (LogData::TimeChange(primitives::decode_real(octets)?), end)
123    } else {
124        return Err(Error::decoding(
125            offset,
126            "log-data expected context [0], constructed [1], or context [2]",
127        ));
128    };
129    expect_end(data, end, offset, LOG_DATA)?;
130    Ok(log_data)
131}
132
133fn decode_values(data: &[u8], offset: usize) -> Result<Vec<LogValue>, Error> {
134    let mut values = Vec::new();
135    let mut pos = 0;
136    while pos < data.len() {
137        let (tag, start) = tags::decode_tag(data, pos)?;
138        let (value, end) = if tag.is_opening_tag(FAILURE) {
139            let (body, end) = tags::extract_context_value(data, start, FAILURE)?;
140            let (error_class, error_code) = decode_failure(body, offset, FAILURE_FIELD)?;
141            let value = LogValue::Failure {
142                error_class,
143                error_code,
144            };
145            (value, end)
146        } else if tag.is_opening_tag(ANY) {
147            let (body, end) = tags::extract_context_value(data, start, ANY)?;
148            (LogValue::AnyValue(decode_any_value(body)?), end)
149        } else if tag.class == tags::TagClass::Context && !tag.is_opening && !tag.is_closing {
150            let (octets, end) = contents(data, start, tag.length)?;
151            (decode_primitive(tag.number, octets, offset)?, end)
152        } else {
153            return Err(Error::decoding(offset, "log-data entry has an unknown tag"));
154        };
155        values.push(value);
156        pos = end;
157    }
158    Ok(values)
159}
160
161fn decode_primitive(number: u8, contents: &[u8], offset: usize) -> Result<LogValue, Error> {
162    Ok(match number {
163        BOOLEAN => match contents {
164            [0] => LogValue::BooleanValue(false),
165            [1] => LogValue::BooleanValue(true),
166            _ => return Err(Error::decoding(offset, "boolean-value must be one octet")),
167        },
168        REAL => LogValue::RealValue(primitives::decode_real(contents)?),
169        ENUMERATED => LogValue::EnumValue(primitives::decode_unsigned(contents)?),
170        UNSIGNED => LogValue::UnsignedValue(primitives::decode_unsigned(contents)?),
171        INTEGER => LogValue::SignedValue(decode_integer(contents, offset)?),
172        BIT_STRING => {
173            let (unused_bits, data) = primitives::decode_bit_string(contents)?;
174            LogValue::BitstringValue { unused_bits, data }
175        }
176        NULL if contents.is_empty() => LogValue::NullValue,
177        _ => return Err(Error::decoding(offset, "log-data entry has an unknown tag")),
178    })
179}
bacnet_encoding/constructed/log_multiple_record.rs

bacnet_encoding/constructed/
log_multiple_record.rs
