hyper_util/client/legacy/connect/
dns.rs

1//! DNS Resolution used by the `HttpConnector`.
2//!
3//! This module contains:
4//!
5//! - A [`GaiResolver`](GaiResolver) that is the default resolver for the
6//!   `HttpConnector`.
7//! - The `Name` type used as an argument to custom resolvers.
8//!
9//! # Resolvers are `Service`s
10//!
11//! A resolver is just a
12//! `Service<Name, Response = impl Iterator<Item = SocketAddr>>`.
13//!
14//! A simple resolver that ignores the name and always returns a specific
15//! address:
16//!
17//! ```rust,ignore
18//! use std::{convert::Infallible, iter, net::SocketAddr};
19//!
20//! let resolver = tower::service_fn(|_name| async {
21//!     Ok::<_, Infallible>(iter::once(SocketAddr::from(([127, 0, 0, 1], 8080))))
22//! });
23//! ```
24use std::error::Error;
25use std::future::Future;
26use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
27use std::pin::Pin;
28use std::str::FromStr;
29use std::task::{self, Poll};
30use std::{fmt, io, vec};
31
32use tokio::task::JoinHandle;
33use tower_service::Service;
34use tracing::debug_span;
35
36pub(super) use self::sealed::Resolve;
37
38/// A domain name to resolve into IP addresses.
39#[derive(Clone, Hash, Eq, PartialEq)]
40pub struct Name {
41    host: Box<str>,
42}
43
44/// A resolver using blocking `getaddrinfo` calls in a threadpool.
45#[derive(Clone)]
46pub struct GaiResolver {
47    _priv: (),
48}
49
50/// An iterator of IP addresses returned from `getaddrinfo`.
51pub struct GaiAddrs {
52    inner: SocketAddrs,
53}
54
55/// A future to resolve a name returned by `GaiResolver`.
56pub struct GaiFuture {
57    inner: JoinHandle<Result<SocketAddrs, io::Error>>,
58}
59
60impl Name {
61    pub(super) fn new(host: Box<str>) -> Name {
62        Name { host }
63    }
64
65    /// View the hostname as a string slice.
66    pub fn as_str(&self) -> &str {
67        &self.host
68    }
69}
70
71impl fmt::Debug for Name {
72    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
73        fmt::Debug::fmt(&self.host, f)
74    }
75}
76
77impl fmt::Display for Name {
78    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
79        fmt::Display::fmt(&self.host, f)
80    }
81}
82
83impl FromStr for Name {
84    type Err = InvalidNameError;
85
86    fn from_str(host: &str) -> Result<Self, Self::Err> {
87        // Possibly add validation later
88        Ok(Name::new(host.into()))
89    }
90}
91
92/// Error indicating a given string was not a valid domain name.
93#[derive(Debug)]
94pub struct InvalidNameError(());
95
96impl fmt::Display for InvalidNameError {
97    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
98        f.write_str("Not a valid domain name")
99    }
100}
101
102impl Error for InvalidNameError {}
103
104impl GaiResolver {
105    /// Construct a new `GaiResolver`.
106    pub fn new() -> Self {
107        GaiResolver { _priv: () }
108    }
109}
110
111impl Service<Name> for GaiResolver {
112    type Response = GaiAddrs;
113    type Error = io::Error;
114    type Future = GaiFuture;
115
116    fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), io::Error>> {
117        Poll::Ready(Ok(()))
118    }
119
120    fn call(&mut self, name: Name) -> Self::Future {
121        let span = debug_span!("resolve", host = %name.host);
122        let blocking = tokio::task::spawn_blocking(move || {
123            let _enter = span.enter();
124            (&*name.host, 0)
125                .to_socket_addrs()
126                .map(|i| SocketAddrs { iter: i })
127        });
128
129        GaiFuture { inner: blocking }
130    }
131}
132
133impl fmt::Debug for GaiResolver {
134    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
135        f.pad("GaiResolver")
136    }
137}
138
139impl Future for GaiFuture {
140    type Output = Result<GaiAddrs, io::Error>;
141
142    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
143        Pin::new(&mut self.inner).poll(cx).map(|res| match res {
144            Ok(Ok(addrs)) => Ok(GaiAddrs { inner: addrs }),
145            Ok(Err(err)) => Err(err),
146            Err(join_err) => {
147                if join_err.is_cancelled() {
148                    Err(io::Error::new(io::ErrorKind::Interrupted, join_err))
149                } else {
150                    panic!("gai background task failed: {:?}", join_err)
151                }
152            }
153        })
154    }
155}
156
157impl fmt::Debug for GaiFuture {
158    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
159        f.pad("GaiFuture")
160    }
161}
162
163impl Drop for GaiFuture {
164    fn drop(&mut self) {
165        self.inner.abort();
166    }
167}
168
169impl Iterator for GaiAddrs {
170    type Item = SocketAddr;
171
172    fn next(&mut self) -> Option<Self::Item> {
173        self.inner.next()
174    }
175}
176
177impl fmt::Debug for GaiAddrs {
178    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
179        f.pad("GaiAddrs")
180    }
181}
182
183pub(super) struct SocketAddrs {
184    iter: vec::IntoIter<SocketAddr>,
185}
186
187impl SocketAddrs {
188    pub(super) fn new(addrs: Vec<SocketAddr>) -> Self {
189        SocketAddrs {
190            iter: addrs.into_iter(),
191        }
192    }
193
194    pub(super) fn try_parse(host: &str, port: u16) -> Option<SocketAddrs> {
195        if let Ok(addr) = host.parse::<Ipv4Addr>() {
196            let addr = SocketAddrV4::new(addr, port);
197            return Some(SocketAddrs {
198                iter: vec![SocketAddr::V4(addr)].into_iter(),
199            });
200        }
201        if let Ok(addr) = host.parse::<Ipv6Addr>() {
202            let addr = SocketAddrV6::new(addr, port, 0, 0);
203            return Some(SocketAddrs {
204                iter: vec![SocketAddr::V6(addr)].into_iter(),
205            });
206        }
207        None
208    }
209
210    #[inline]
211    fn filter(self, predicate: impl FnMut(&SocketAddr) -> bool) -> SocketAddrs {
212        SocketAddrs::new(self.iter.filter(predicate).collect())
213    }
214
215    pub(super) fn split_by_preference(
216        self,
217        local_addr_ipv4: Option<Ipv4Addr>,
218        local_addr_ipv6: Option<Ipv6Addr>,
219    ) -> (SocketAddrs, SocketAddrs) {
220        match (local_addr_ipv4, local_addr_ipv6) {
221            (Some(_), None) => (self.filter(SocketAddr::is_ipv4), SocketAddrs::new(vec![])),
222            (None, Some(_)) => (self.filter(SocketAddr::is_ipv6), SocketAddrs::new(vec![])),
223            _ => {
224                let preferring_v6 = self
225                    .iter
226                    .as_slice()
227                    .first()
228                    .map(SocketAddr::is_ipv6)
229                    .unwrap_or(false);
230
231                let (preferred, fallback) = self
232                    .iter
233                    .partition::<Vec<_>, _>(|addr| addr.is_ipv6() == preferring_v6);
234
235                (SocketAddrs::new(preferred), SocketAddrs::new(fallback))
236            }
237        }
238    }
239
240    pub(super) fn is_empty(&self) -> bool {
241        self.iter.as_slice().is_empty()
242    }
243
244    pub(super) fn len(&self) -> usize {
245        self.iter.as_slice().len()
246    }
247}
248
249impl Iterator for SocketAddrs {
250    type Item = SocketAddr;
251    #[inline]
252    fn next(&mut self) -> Option<SocketAddr> {
253        self.iter.next()
254    }
255}
256
257mod sealed {
258    use std::future::Future;
259    use std::task::{self, Poll};
260
261    use super::{Name, SocketAddr};
262    use tower_service::Service;
263
264    // "Trait alias" for `Service<Name, Response = Addrs>`
265    pub trait Resolve {
266        type Addrs: Iterator<Item = SocketAddr>;
267        type Error: Into<Box<dyn std::error::Error + Send + Sync>>;
268        type Future: Future<Output = Result<Self::Addrs, Self::Error>>;
269
270        fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>>;
271        fn resolve(&mut self, name: Name) -> Self::Future;
272    }
273
274    impl<S> Resolve for S
275    where
276        S: Service<Name>,
277        S::Response: Iterator<Item = SocketAddr>,
278        S::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
279    {
280        type Addrs = S::Response;
281        type Error = S::Error;
282        type Future = S::Future;
283
284        fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
285            Service::poll_ready(self, cx)
286        }
287
288        fn resolve(&mut self, name: Name) -> Self::Future {
289            Service::call(self, name)
290        }
291    }
292}
293
294pub(super) async fn resolve<R>(resolver: &mut R, name: Name) -> Result<R::Addrs, R::Error>
295where
296    R: Resolve,
297{
298    futures_util::future::poll_fn(|cx| resolver.poll_ready(cx)).await?;
299    resolver.resolve(name).await
300}
301
302#[cfg(test)]
303mod tests {
304    use super::*;
305    use std::net::{Ipv4Addr, Ipv6Addr};
306
307    #[test]
308    fn test_ip_addrs_split_by_preference() {
309        let ip_v4 = Ipv4Addr::new(127, 0, 0, 1);
310        let ip_v6 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
311        let v4_addr = (ip_v4, 80).into();
312        let v6_addr = (ip_v6, 80).into();
313
314        let (mut preferred, mut fallback) = SocketAddrs {
315            iter: vec![v4_addr, v6_addr].into_iter(),
316        }
317        .split_by_preference(None, None);
318        assert!(preferred.next().unwrap().is_ipv4());
319        assert!(fallback.next().unwrap().is_ipv6());
320
321        let (mut preferred, mut fallback) = SocketAddrs {
322            iter: vec![v6_addr, v4_addr].into_iter(),
323        }
324        .split_by_preference(None, None);
325        assert!(preferred.next().unwrap().is_ipv6());
326        assert!(fallback.next().unwrap().is_ipv4());
327
328        let (mut preferred, mut fallback) = SocketAddrs {
329            iter: vec![v4_addr, v6_addr].into_iter(),
330        }
331        .split_by_preference(Some(ip_v4), Some(ip_v6));
332        assert!(preferred.next().unwrap().is_ipv4());
333        assert!(fallback.next().unwrap().is_ipv6());
334
335        let (mut preferred, mut fallback) = SocketAddrs {
336            iter: vec![v6_addr, v4_addr].into_iter(),
337        }
338        .split_by_preference(Some(ip_v4), Some(ip_v6));
339        assert!(preferred.next().unwrap().is_ipv6());
340        assert!(fallback.next().unwrap().is_ipv4());
341
342        let (mut preferred, fallback) = SocketAddrs {
343            iter: vec![v4_addr, v6_addr].into_iter(),
344        }
345        .split_by_preference(Some(ip_v4), None);
346        assert!(preferred.next().unwrap().is_ipv4());
347        assert!(fallback.is_empty());
348
349        let (mut preferred, fallback) = SocketAddrs {
350            iter: vec![v4_addr, v6_addr].into_iter(),
351        }
352        .split_by_preference(None, Some(ip_v6));
353        assert!(preferred.next().unwrap().is_ipv6());
354        assert!(fallback.is_empty());
355    }
356
357    #[test]
358    fn test_name_from_str() {
359        const DOMAIN: &str = "test.example.com";
360        let name = Name::from_str(DOMAIN).expect("Should be a valid domain");
361        assert_eq!(name.as_str(), DOMAIN);
362        assert_eq!(name.to_string(), DOMAIN);
363    }
364}
hyper_util/client/legacy/connect/dns.rs

hyper_util/client/legacy/connect/
dns.rs
