reqwest/dns/
resolve.rs

Help
1use hyper_util::client::legacy::connect::dns::Name as HyperName;
2use tower_service::Service;
3
4use std::collections::HashMap;
5use std::future::Future;
6use std::net::SocketAddr;
7use std::pin::Pin;
8use std::str::FromStr;
9use std::sync::Arc;
10use std::task::{Context, Poll};
11
12use crate::error::BoxError;
13
14/// Alias for an `Iterator` trait object over `SocketAddr`.
15pub type Addrs = Box<dyn Iterator<Item = SocketAddr> + Send>;
16
17/// Alias for the `Future` type returned by a DNS resolver.
18pub type Resolving = Pin<Box<dyn Future<Output = Result<Addrs, BoxError>> + Send>>;
19
20/// Trait for customizing DNS resolution in reqwest.
21pub trait Resolve: Send + Sync {
22    /// Performs DNS resolution on a `Name`.
23    /// The return type is a future containing an iterator of `SocketAddr`.
24    ///
25    /// It differs from `tower_service::Service<Name>` in several ways:
26    ///  * It is assumed that `resolve` will always be ready to poll.
27    ///  * It does not need a mutable reference to `self`.
28    ///  * Since trait objects cannot make use of associated types, it requires
29    ///    wrapping the returned `Future` and its contained `Iterator` with `Box`.
30    ///
31    /// Explicitly specified port in the URL will override any port in the resolved `SocketAddr`s.
32    /// Otherwise, port `0` will be replaced by the conventional port for the given scheme (e.g. 80 for http).
33    fn resolve(&self, name: Name) -> Resolving;
34}
35
36/// A name that must be resolved to addresses.
37#[derive(Debug)]
38pub struct Name(pub(super) HyperName);
39
40impl Name {
41    /// View the name as a string.
42    pub fn as_str(&self) -> &str {
43        self.0.as_str()
44    }
45}
46
47impl FromStr for Name {
48    type Err = sealed::InvalidNameError;
49
50    fn from_str(host: &str) -> Result<Self, Self::Err> {
51        HyperName::from_str(host)
52            .map(Name)
53            .map_err(|_| sealed::InvalidNameError { _ext: () })
54    }
55}
56
57#[derive(Clone)]
58pub(crate) struct DynResolver {
59    resolver: Arc<dyn Resolve>,
60}
61
62impl DynResolver {
63    pub(crate) fn new(resolver: Arc<dyn Resolve>) -> Self {
64        Self { resolver }
65    }
66}
67
68impl Service<HyperName> for DynResolver {
69    type Response = Addrs;
70    type Error = BoxError;
71    type Future = Resolving;
72
73    fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
74        Poll::Ready(Ok(()))
75    }
76
77    fn call(&mut self, name: HyperName) -> Self::Future {
78        self.resolver.resolve(Name(name))
79    }
80}
81
82pub(crate) struct DnsResolverWithOverrides {
83    dns_resolver: Arc<dyn Resolve>,
84    overrides: Arc<HashMap<String, Vec<SocketAddr>>>,
85}
86
87impl DnsResolverWithOverrides {
88    pub(crate) fn new(
89        dns_resolver: Arc<dyn Resolve>,
90        overrides: HashMap<String, Vec<SocketAddr>>,
91    ) -> Self {
92        DnsResolverWithOverrides {
93            dns_resolver,
94            overrides: Arc::new(overrides),
95        }
96    }
97}
98
99impl Resolve for DnsResolverWithOverrides {
100    fn resolve(&self, name: Name) -> Resolving {
101        match self.overrides.get(name.as_str()) {
102            Some(dest) => {
103                let addrs: Addrs = Box::new(dest.clone().into_iter());
104                Box::pin(std::future::ready(Ok(addrs)))
105            }
106            None => self.dns_resolver.resolve(name),
107        }
108    }
109}
110
111mod sealed {
112    use std::fmt;
113
114    #[derive(Debug)]
115    pub struct InvalidNameError {
116        pub(super) _ext: (),
117    }
118
119    impl fmt::Display for InvalidNameError {
120        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
121            f.write_str("invalid DNS name")
122        }
123    }
124
125    impl std::error::Error for InvalidNameError {}
126}
reqwest/dns/resolve.rs

reqwest/dns/
resolve.rs
