libmdns 0.10.1

mDNS Responder library for building discoverable LAN services in Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

use std::io;
use std::net::{Ipv4Addr, Ipv6Addr};

use byteorder::{BigEndian, ByteOrder, WriteBytesExt};

use super::{Error, Name, Type};

/// The enumeration that represents known types of DNS resource records data
#[derive(Debug, Clone)]
#[allow(clippy::upper_case_acronyms)]
pub enum RRData<'a> {
    CNAME(Name<'a>),
    NS(Name<'a>),
    PTR(Name<'a>),
    A(Ipv4Addr),
    AAAA(Ipv6Addr),
    SRV {
        priority: u16,
        weight: u16,
        port: u16,
        target: Name<'a>,
    },
    MX {
        preference: u16,
        exchange: Name<'a>,
    },
    TXT(&'a [u8]),
    // Anything that can't be parsed yet
    Unknown {
        typ: Type,
        data: &'a [u8],
    },
}

impl<'a> RRData<'a> {
    pub fn typ(&self) -> Type {
        match *self {
            RRData::CNAME(..) => Type::CNAME,
            RRData::NS(..) => Type::NS,
            RRData::PTR(..) => Type::PTR,
            RRData::A(..) => Type::A,
            RRData::AAAA(..) => Type::AAAA,
            RRData::SRV { .. } => Type::SRV,
            RRData::MX { .. } => Type::MX,
            RRData::TXT(..) => Type::TXT,
            RRData::Unknown { typ, .. } => typ,
        }
    }

    pub fn write_to<T: io::Write>(&self, writer: &mut T) -> io::Result<()> {
        match *self {
            RRData::CNAME(ref name) | RRData::NS(ref name) | RRData::PTR(ref name) => {
                name.write_to(writer)
            }

            RRData::A(ip) => writer.write_u32::<BigEndian>(ip.into()),

            RRData::AAAA(ip) => {
                for segment in &ip.segments() {
                    writer.write_u16::<BigEndian>(*segment)?;
                }
                Ok(())
            }
            RRData::SRV {
                priority,
                weight,
                port,
                ref target,
            } => {
                writer.write_u16::<BigEndian>(priority)?;
                writer.write_u16::<BigEndian>(weight)?;
                writer.write_u16::<BigEndian>(port)?;
                target.write_to(writer)
            }
            RRData::MX {
                preference,
                ref exchange,
            } => {
                writer.write_u16::<BigEndian>(preference)?;
                exchange.write_to(writer)
            }
            RRData::TXT(data) | RRData::Unknown { data, .. } => writer.write_all(data),
        }
    }

    pub fn parse(typ: Type, rdata: &'a [u8], original: &'a [u8]) -> Result<RRData<'a>, Error> {
        match typ {
            Type::A => {
                if rdata.len() != 4 {
                    return Err(Error::WrongRdataLength);
                }
                Ok(RRData::A(Ipv4Addr::from(BigEndian::read_u32(rdata))))
            }
            Type::AAAA => {
                if rdata.len() != 16 {
                    return Err(Error::WrongRdataLength);
                }
                Ok(RRData::AAAA(Ipv6Addr::new(
                    BigEndian::read_u16(&rdata[0..2]),
                    BigEndian::read_u16(&rdata[2..4]),
                    BigEndian::read_u16(&rdata[4..6]),
                    BigEndian::read_u16(&rdata[6..8]),
                    BigEndian::read_u16(&rdata[8..10]),
                    BigEndian::read_u16(&rdata[10..12]),
                    BigEndian::read_u16(&rdata[12..14]),
                    BigEndian::read_u16(&rdata[14..16]),
                )))
            }
            Type::CNAME => Ok(RRData::CNAME(Name::scan(rdata, original)?.0)),
            Type::NS => Ok(RRData::NS(Name::scan(rdata, original)?.0)),
            Type::PTR => Ok(RRData::PTR(Name::scan(rdata, original)?.0)),
            Type::MX => {
                if rdata.len() < 3 {
                    return Err(Error::WrongRdataLength);
                }
                Ok(RRData::MX {
                    preference: BigEndian::read_u16(&rdata[..2]),
                    exchange: Name::scan(&rdata[2..], original)?.0,
                })
            }
            Type::SRV => {
                if rdata.len() < 7 {
                    return Err(Error::WrongRdataLength);
                }
                Ok(RRData::SRV {
                    priority: BigEndian::read_u16(&rdata[..2]),
                    weight: BigEndian::read_u16(&rdata[2..4]),
                    port: BigEndian::read_u16(&rdata[4..6]),
                    target: Name::scan(&rdata[6..], original)?.0,
                })
            }
            Type::TXT => Ok(RRData::TXT(rdata)),
            typ => Ok(RRData::Unknown { typ, data: rdata }),
        }
    }
}