simple_dns/dns/rdata/
srv.rs

1use std::convert::TryInto;
2
3use crate::dns::WireFormat;
4use crate::Name;
5
6use super::RR;
7
8/// SRV records specifies the location of the server(s) for a specific protocol and domain.
9#[derive(Debug, PartialEq, Eq, Hash, Clone)]
10pub struct SRV<'a> {
11    /// The priority of this target host.  
12    /// A client MUST attempt to contact the target host with the lowest-numbered priority it can
13    /// reach; target hosts with the same priority SHOULD be tried in an order defined by the weight field.
14    pub priority: u16,
15    /// A server selection mechanism.  
16    /// The weight field specifies arelative weight for entries with the same priority.  
17    /// Larger weights SHOULD be given a proportionately higher probability of being selected.
18    pub weight: u16,
19    /// The port on this target host of this service
20    pub port: u16,
21    /// The domain name of the target host
22    pub target: Name<'a>,
23}
24
25impl<'a> RR for SRV<'a> {
26    const TYPE_CODE: u16 = 33;
27}
28
29impl<'a> SRV<'a> {
30    /// Transforms the inner data into its owned type
31    pub fn into_owned<'b>(self) -> SRV<'b> {
32        SRV {
33            priority: self.priority,
34            weight: self.weight,
35            port: self.port,
36            target: self.target.into_owned(),
37        }
38    }
39}
40
41impl<'a> WireFormat<'a> for SRV<'a> {
42    fn parse(data: &'a [u8], position: &mut usize) -> crate::Result<Self>
43    where
44        Self: Sized,
45    {
46        let priority = u16::from_be_bytes(data[*position..*position + 2].try_into()?);
47        let weight = u16::from_be_bytes(data[*position + 2..*position + 4].try_into()?);
48        let port = u16::from_be_bytes(data[*position + 4..*position + 6].try_into()?);
49        *position += 6;
50        let target = Name::parse(data, position)?;
51
52        Ok(Self {
53            priority,
54            weight,
55            port,
56            target,
57        })
58    }
59
60    fn write_to<T: std::io::Write>(&self, out: &mut T) -> crate::Result<()> {
61        out.write_all(&self.priority.to_be_bytes())?;
62        out.write_all(&self.weight.to_be_bytes())?;
63        out.write_all(&self.port.to_be_bytes())?;
64
65        self.target.write_to(out)
66    }
67
68    fn len(&self) -> usize {
69        self.target.len() + 6
70    }
71}
72
73#[cfg(test)]
74mod tests {
75    use std::{collections::HashMap, io::Cursor};
76
77    use crate::{rdata::RData, ResourceRecord};
78
79    use super::*;
80
81    #[test]
82    fn parse_and_write_srv() {
83        let srv = SRV {
84            priority: 1,
85            weight: 2,
86            port: 3,
87            target: Name::new("_srv._tcp.example.com").unwrap(),
88        };
89
90        let mut bytes = Vec::new();
91        assert!(srv.write_to(&mut bytes).is_ok());
92
93        let srv = SRV::parse(&bytes, &mut 0);
94        assert!(srv.is_ok());
95        let srv = srv.unwrap();
96
97        assert_eq!(1, srv.priority);
98        assert_eq!(2, srv.weight);
99        assert_eq!(3, srv.port);
100        assert_eq!(bytes.len(), srv.len());
101    }
102
103    #[test]
104    fn srv_should_not_be_compressed() {
105        let srv = SRV {
106            priority: 1,
107            weight: 2,
108            port: 3,
109            target: Name::new("_srv._tcp.example.com").unwrap(),
110        };
111
112        let mut plain = Vec::new();
113        let mut compressed = Cursor::new(Vec::new());
114        let mut names = HashMap::new();
115
116        assert!(srv.write_to(&mut plain).is_ok());
117        assert!(srv.write_compressed_to(&mut compressed, &mut names).is_ok());
118
119        assert_eq!(plain, compressed.into_inner());
120    }
121
122    #[test]
123    fn parse_sample() -> Result<(), Box<dyn std::error::Error>> {
124        let sample_file = std::fs::read("samples/zonefile/SRV.sample")?;
125
126        let sample_rdata = match ResourceRecord::parse(&sample_file, &mut 0)?.rdata {
127            RData::SRV(rdata) => rdata,
128            _ => unreachable!(),
129        };
130
131        assert_eq!(sample_rdata.priority, 65535);
132        assert_eq!(sample_rdata.weight, 65535);
133        assert_eq!(sample_rdata.port, 65535);
134        assert_eq!(sample_rdata.target, "old-slow-box.sample".try_into()?);
135
136        Ok(())
137    }
138}
simple_dns/dns/rdata/srv.rs

simple_dns/dns/rdata/
srv.rs
