dvb_si/descriptors/
default_authority.rs

1//! Default Authority Descriptor — ETSI TS 102 323 §12.2.1 (tag 0x73).
2//!
3//! Carried inside NIT, BAT, SDT, EIT to provide the default TV-Anytime
4//! authority prefix used when resolving relative CRIDs.
5
6use super::descriptor_body;
7use crate::error::{Error, Result};
8use dvb_common::{Parse, Serialize};
9
10/// Descriptor tag for default_authority_descriptor.
11pub const TAG: u8 = 0x73;
12const HEADER_LEN: usize = 2;
13
14/// Default Authority Descriptor.
15#[derive(Debug, Clone, PartialEq, Eq)]
16#[cfg_attr(feature = "serde", derive(serde::Serialize))]
17#[cfg_attr(feature = "yoke", derive(yoke::Yokeable))]
18pub struct DefaultAuthorityDescriptor<'a> {
19    /// Raw ASCII default authority bytes (e.g. b"bbc.co.uk").
20    pub default_authority: &'a [u8],
21}
22
23impl<'a> Parse<'a> for DefaultAuthorityDescriptor<'a> {
24    type Error = crate::error::Error;
25    fn parse(bytes: &'a [u8]) -> Result<Self> {
26        let body = descriptor_body(
27            bytes,
28            TAG,
29            "DefaultAuthorityDescriptor",
30            "unexpected tag for default authority descriptor",
31        )?;
32        Ok(Self {
33            default_authority: body,
34        })
35    }
36}
37
38impl Serialize for DefaultAuthorityDescriptor<'_> {
39    type Error = crate::error::Error;
40    fn serialized_len(&self) -> usize {
41        HEADER_LEN + self.default_authority.len()
42    }
43
44    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
45        let len = self.serialized_len();
46        if buf.len() < len {
47            return Err(Error::OutputBufferTooSmall {
48                need: len,
49                have: buf.len(),
50            });
51        }
52        buf[0] = TAG;
53        buf[1] = self.default_authority.len() as u8;
54        buf[HEADER_LEN..len].copy_from_slice(self.default_authority);
55        Ok(len)
56    }
57}
58impl<'a> crate::traits::DescriptorDef<'a> for DefaultAuthorityDescriptor<'a> {
59    const TAG: u8 = TAG;
60    const NAME: &'static str = "DEFAULT_AUTHORITY";
61}
62
63#[cfg(test)]
64mod tests {
65    use super::*;
66
67    #[test]
68    fn parse_extracts_authority_bytes() {
69        let bytes = [TAG, 9, b'b', b'b', b'c', b'.', b'c', b'o', b'.', b'u', b'k'];
70        let d = DefaultAuthorityDescriptor::parse(&bytes).unwrap();
71        assert_eq!(d.default_authority, b"bbc.co.uk");
72    }
73
74    #[test]
75    fn parse_rejects_wrong_tag() {
76        assert!(matches!(
77            DefaultAuthorityDescriptor::parse(&[0x7A, 1, 0]).unwrap_err(),
78            Error::InvalidDescriptor { tag: 0x7A, .. }
79        ));
80    }
81
82    #[test]
83    fn parse_rejects_short_header() {
84        assert!(matches!(
85            DefaultAuthorityDescriptor::parse(&[TAG]).unwrap_err(),
86            Error::BufferTooShort { .. }
87        ));
88    }
89
90    #[test]
91    fn parse_rejects_length_overrunning_buffer() {
92        let bytes = [TAG, 5, 1, 2, 3];
93        assert!(matches!(
94            DefaultAuthorityDescriptor::parse(&bytes).unwrap_err(),
95            Error::BufferTooShort { .. }
96        ));
97    }
98
99    #[test]
100    fn empty_authority_is_valid() {
101        let bytes = [TAG, 0];
102        let d = DefaultAuthorityDescriptor::parse(&bytes).unwrap();
103        assert!(d.default_authority.is_empty());
104    }
105
106    #[test]
107    fn serialize_round_trip() {
108        let d = DefaultAuthorityDescriptor {
109            default_authority: b"example.com",
110        };
111        let mut buf = vec![0u8; d.serialized_len()];
112        d.serialize_into(&mut buf).unwrap();
113        assert_eq!(DefaultAuthorityDescriptor::parse(&buf).unwrap(), d);
114    }
115
116    #[test]
117    fn serialize_rejects_too_small_buffer() {
118        let d = DefaultAuthorityDescriptor {
119            default_authority: b"test",
120        };
121        let mut buf = vec![0u8; 1];
122        assert!(matches!(
123            d.serialize_into(&mut buf).unwrap_err(),
124            Error::OutputBufferTooSmall { .. }
125        ));
126    }
127}
dvb_si/descriptors/default_authority.rs

dvb_si/descriptors/
default_authority.rs
