simple_dns/dns/rdata/
mx.rs

1use std::{collections::HashMap, convert::TryInto};
2
3use crate::dns::{name::Label, Name, WireFormat};
4
5use super::RR;
6
7/// MX is used to acquire mail exchange information
8#[derive(Debug, PartialEq, Eq, Hash, Clone)]
9pub struct MX<'a> {
10    /// A 16 bit integer which specifies the preference given to this RR among others at the same owner.  
11    /// Lower values are preferred.
12    pub preference: u16,
13
14    /// A [Name](`Name`) which specifies a host willing to act as a mail exchange for the owner name.
15    pub exchange: Name<'a>,
16}
17
18impl<'a> RR for MX<'a> {
19    const TYPE_CODE: u16 = 15;
20}
21
22impl<'a> MX<'a> {
23    /// Transforms the inner data into its owned type
24    pub fn into_owned<'b>(self) -> MX<'b> {
25        MX {
26            preference: self.preference,
27            exchange: self.exchange.into_owned(),
28        }
29    }
30}
31
32impl<'a> WireFormat<'a> for MX<'a> {
33    fn parse(data: &'a [u8], position: &mut usize) -> crate::Result<Self>
34    where
35        Self: Sized,
36    {
37        let preference = u16::from_be_bytes(data[*position..*position + 2].try_into()?);
38        *position += 2;
39        let exchange = Name::parse(data, position)?;
40
41        Ok(Self {
42            preference,
43            exchange,
44        })
45    }
46
47    fn write_to<T: std::io::Write>(&self, out: &mut T) -> crate::Result<()> {
48        out.write_all(&self.preference.to_be_bytes())?;
49        self.exchange.write_to(out)
50    }
51
52    fn write_compressed_to<T: std::io::Write + std::io::Seek>(
53        &'a self,
54        out: &mut T,
55        name_refs: &mut HashMap<&'a [Label<'a>], usize>,
56    ) -> crate::Result<()> {
57        out.write_all(&self.preference.to_be_bytes())?;
58        self.exchange.write_compressed_to(out, name_refs)
59    }
60
61    fn len(&self) -> usize {
62        self.exchange.len() + 2
63    }
64}
65
66#[cfg(test)]
67mod tests {
68    use crate::{rdata::RData, ResourceRecord};
69
70    use super::*;
71
72    #[test]
73    fn parse_and_write_mx() {
74        let mx = MX {
75            preference: 10,
76            exchange: Name::new("e.exchange.com").unwrap(),
77        };
78
79        let mut data = Vec::new();
80        assert!(mx.write_to(&mut data).is_ok());
81
82        let mx = MX::parse(&data, &mut 0);
83        assert!(mx.is_ok());
84        let mx = mx.unwrap();
85
86        assert_eq!(data.len(), mx.len());
87        assert_eq!(10, mx.preference);
88        assert_eq!("e.exchange.com", mx.exchange.to_string());
89    }
90
91    #[test]
92    fn parse_sample() -> Result<(), Box<dyn std::error::Error>> {
93        let sample_file = std::fs::read("samples/zonefile/MX.sample")?;
94
95        let sample_rdata = match ResourceRecord::parse(&sample_file, &mut 0)?.rdata {
96            RData::MX(rdata) => rdata,
97            _ => unreachable!(),
98        };
99
100        assert_eq!(sample_rdata.preference, 10);
101        assert_eq!(sample_rdata.exchange, "VENERA.sample".try_into()?);
102        Ok(())
103    }
104}
simple_dns/dns/rdata/mx.rs

simple_dns/dns/rdata/
mx.rs
