simple_dns/dns/rdata/
mx.rs

1use std::collections::HashMap;
2
3use crate::{
4    bytes_buffer::BytesBuffer,
5    dns::{name::Label, Name, WireFormat},
6};
7
8use super::RR;
9
10/// MX is used to acquire mail exchange information
11#[derive(Debug, PartialEq, Eq, Hash, Clone)]
12pub struct MX<'a> {
13    /// A 16 bit integer which specifies the preference given to this RR among others at the same owner.  
14    /// Lower values are preferred.
15    pub preference: u16,
16
17    /// A [Name](`Name`) which specifies a host willing to act as a mail exchange for the owner name.
18    pub exchange: Name<'a>,
19}
20
21impl RR for MX<'_> {
22    const TYPE_CODE: u16 = 15;
23}
24
25impl MX<'_> {
26    /// Transforms the inner data into its owned type
27    pub fn into_owned<'b>(self) -> MX<'b> {
28        MX {
29            preference: self.preference,
30            exchange: self.exchange.into_owned(),
31        }
32    }
33}
34
35impl<'a> WireFormat<'a> for MX<'a> {
36    const MINIMUM_LEN: usize = 2;
37
38    fn parse(data: &mut BytesBuffer<'a>) -> crate::Result<Self>
39    where
40        Self: Sized,
41    {
42        let preference = data.get_u16()?;
43        let exchange = Name::parse(data)?;
44
45        Ok(Self {
46            preference,
47            exchange,
48        })
49    }
50
51    fn write_to<T: std::io::Write>(&self, out: &mut T) -> crate::Result<()> {
52        out.write_all(&self.preference.to_be_bytes())?;
53        self.exchange.write_to(out)
54    }
55
56    fn write_compressed_to<T: std::io::Write + std::io::Seek>(
57        &'a self,
58        out: &mut T,
59        name_refs: &mut HashMap<&'a [Label<'a>], usize>,
60    ) -> crate::Result<()> {
61        out.write_all(&self.preference.to_be_bytes())?;
62        self.exchange.write_compressed_to(out, name_refs)
63    }
64
65    fn len(&self) -> usize {
66        self.exchange.len() + Self::MINIMUM_LEN
67    }
68}
69
70#[cfg(test)]
71mod tests {
72    use crate::{rdata::RData, ResourceRecord};
73
74    use super::*;
75
76    #[test]
77    fn parse_and_write_mx() {
78        let mx = MX {
79            preference: 10,
80            exchange: Name::new("e.exchange.com").unwrap(),
81        };
82
83        let mut data = Vec::new();
84        assert!(mx.write_to(&mut data).is_ok());
85
86        let mx = MX::parse(&mut data[..].into());
87        assert!(mx.is_ok());
88        let mx = mx.unwrap();
89
90        assert_eq!(data.len(), mx.len());
91        assert_eq!(10, mx.preference);
92        assert_eq!("e.exchange.com", mx.exchange.to_string());
93    }
94
95    #[test]
96    fn parse_sample() -> Result<(), Box<dyn std::error::Error>> {
97        let sample_file = std::fs::read("samples/zonefile/MX.sample")?;
98
99        let sample_rdata = match ResourceRecord::parse(&mut sample_file[..].into())?.rdata {
100            RData::MX(rdata) => rdata,
101            _ => unreachable!(),
102        };
103
104        assert_eq!(sample_rdata.preference, 10);
105        assert_eq!(sample_rdata.exchange, "VENERA.sample".try_into()?);
106        Ok(())
107    }
108}
simple_dns/dns/rdata/mx.rs

simple_dns/dns/rdata/
mx.rs
