420 lines
12 KiB
Rust
420 lines
12 KiB
Rust
//! DNS Resolution used by the `HttpConnector`.
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//!
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//! This module contains:
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//!
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//! - A [`GaiResolver`](GaiResolver) that is the default resolver for the
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//! `HttpConnector`.
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//! - The `Name` type used as an argument to custom resolvers.
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//!
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//! # Resolvers are `Service`s
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//!
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//! A resolver is just a
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//! `Service<Name, Response = impl Iterator<Item = SocketAddr>>`.
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//!
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//! A simple resolver that ignores the name and always returns a specific
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//! address:
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//!
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//! ```rust,ignore
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//! use std::{convert::Infallible, iter, net::SocketAddr};
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//!
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//! let resolver = tower::service_fn(|_name| async {
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//! Ok::<_, Infallible>(iter::once(SocketAddr::from(([127, 0, 0, 1], 8080))))
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//! });
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//! ```
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use std::error::Error;
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use std::future::Future;
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use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
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use std::pin::Pin;
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use std::str::FromStr;
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use std::task::{self, Poll};
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use std::{fmt, io, vec};
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use tokio::task::JoinHandle;
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use tower_service::Service;
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use tracing::debug;
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pub(super) use self::sealed::Resolve;
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/// A domain name to resolve into IP addresses.
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#[derive(Clone, Hash, Eq, PartialEq)]
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pub struct Name {
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host: String,
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}
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/// A resolver using blocking `getaddrinfo` calls in a threadpool.
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#[derive(Clone)]
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pub struct GaiResolver {
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_priv: (),
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}
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/// An iterator of IP addresses returned from `getaddrinfo`.
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pub struct GaiAddrs {
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inner: SocketAddrs,
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}
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/// A future to resolve a name returned by `GaiResolver`.
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pub struct GaiFuture {
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inner: JoinHandle<Result<SocketAddrs, io::Error>>,
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}
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impl Name {
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pub(super) fn new(host: String) -> Name {
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Name { host }
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}
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/// View the hostname as a string slice.
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pub fn as_str(&self) -> &str {
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&self.host
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}
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}
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impl fmt::Debug for Name {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt::Debug::fmt(&self.host, f)
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}
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}
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impl fmt::Display for Name {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt::Display::fmt(&self.host, f)
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}
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}
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impl FromStr for Name {
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type Err = InvalidNameError;
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fn from_str(host: &str) -> Result<Self, Self::Err> {
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// Possibly add validation later
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Ok(Name::new(host.to_owned()))
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}
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}
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/// Error indicating a given string was not a valid domain name.
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#[derive(Debug)]
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pub struct InvalidNameError(());
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impl fmt::Display for InvalidNameError {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_str("Not a valid domain name")
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}
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}
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impl Error for InvalidNameError {}
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impl GaiResolver {
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/// Construct a new `GaiResolver`.
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pub fn new() -> Self {
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GaiResolver { _priv: () }
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}
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}
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impl Service<Name> for GaiResolver {
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type Response = GaiAddrs;
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type Error = io::Error;
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type Future = GaiFuture;
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fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), io::Error>> {
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Poll::Ready(Ok(()))
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}
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fn call(&mut self, name: Name) -> Self::Future {
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let blocking = tokio::task::spawn_blocking(move || {
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debug!("resolving host={:?}", name.host);
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(&*name.host, 0)
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.to_socket_addrs()
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.map(|i| SocketAddrs { iter: i })
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});
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GaiFuture { inner: blocking }
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}
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}
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impl fmt::Debug for GaiResolver {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("GaiResolver")
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}
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}
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impl Future for GaiFuture {
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type Output = Result<GaiAddrs, io::Error>;
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fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
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Pin::new(&mut self.inner).poll(cx).map(|res| match res {
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Ok(Ok(addrs)) => Ok(GaiAddrs { inner: addrs }),
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Ok(Err(err)) => Err(err),
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Err(join_err) => {
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if join_err.is_cancelled() {
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Err(io::Error::new(io::ErrorKind::Interrupted, join_err))
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} else {
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panic!("gai background task failed: {:?}", join_err)
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}
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}
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})
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}
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}
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impl fmt::Debug for GaiFuture {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("GaiFuture")
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}
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}
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impl Iterator for GaiAddrs {
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type Item = SocketAddr;
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fn next(&mut self) -> Option<Self::Item> {
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self.inner.next()
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}
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}
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impl fmt::Debug for GaiAddrs {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("GaiAddrs")
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}
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}
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pub(super) struct SocketAddrs {
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iter: vec::IntoIter<SocketAddr>,
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}
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impl SocketAddrs {
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pub(super) fn new(addrs: Vec<SocketAddr>) -> Self {
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SocketAddrs {
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iter: addrs.into_iter(),
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}
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}
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pub(super) fn try_parse(host: &str, port: u16) -> Option<SocketAddrs> {
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if let Ok(addr) = host.parse::<Ipv4Addr>() {
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let addr = SocketAddrV4::new(addr, port);
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return Some(SocketAddrs {
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iter: vec![SocketAddr::V4(addr)].into_iter(),
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});
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}
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if let Ok(addr) = host.parse::<Ipv6Addr>() {
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let addr = SocketAddrV6::new(addr, port, 0, 0);
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return Some(SocketAddrs {
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iter: vec![SocketAddr::V6(addr)].into_iter(),
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});
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}
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None
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}
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#[inline]
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fn filter(self, predicate: impl FnMut(&SocketAddr) -> bool) -> SocketAddrs {
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SocketAddrs::new(self.iter.filter(predicate).collect())
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}
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pub(super) fn split_by_preference(
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self,
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local_addr_ipv4: Option<Ipv4Addr>,
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local_addr_ipv6: Option<Ipv6Addr>,
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) -> (SocketAddrs, SocketAddrs) {
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match (local_addr_ipv4, local_addr_ipv6) {
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(Some(_), None) => (self.filter(SocketAddr::is_ipv4), SocketAddrs::new(vec![])),
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(None, Some(_)) => (self.filter(SocketAddr::is_ipv6), SocketAddrs::new(vec![])),
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_ => {
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let preferring_v6 = self
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.iter
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.as_slice()
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.first()
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.map(SocketAddr::is_ipv6)
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.unwrap_or(false);
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let (preferred, fallback) = self
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.iter
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.partition::<Vec<_>, _>(|addr| addr.is_ipv6() == preferring_v6);
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(SocketAddrs::new(preferred), SocketAddrs::new(fallback))
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}
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}
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}
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pub(super) fn is_empty(&self) -> bool {
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self.iter.as_slice().is_empty()
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}
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pub(super) fn len(&self) -> usize {
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self.iter.as_slice().len()
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}
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}
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impl Iterator for SocketAddrs {
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type Item = SocketAddr;
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#[inline]
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fn next(&mut self) -> Option<SocketAddr> {
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self.iter.next()
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}
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}
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/*
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/// A resolver using `getaddrinfo` calls via the `tokio_executor::threadpool::blocking` API.
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///
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/// Unlike the `GaiResolver` this will not spawn dedicated threads, but only works when running on the
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/// multi-threaded Tokio runtime.
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#[cfg(feature = "runtime")]
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#[derive(Clone, Debug)]
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pub struct TokioThreadpoolGaiResolver(());
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/// The future returned by `TokioThreadpoolGaiResolver`.
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#[cfg(feature = "runtime")]
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#[derive(Debug)]
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pub struct TokioThreadpoolGaiFuture {
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name: Name,
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}
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#[cfg(feature = "runtime")]
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impl TokioThreadpoolGaiResolver {
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/// Creates a new DNS resolver that will use tokio threadpool's blocking
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/// feature.
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///
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/// **Requires** its futures to be run on the threadpool runtime.
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pub fn new() -> Self {
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TokioThreadpoolGaiResolver(())
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}
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}
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#[cfg(feature = "runtime")]
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impl Service<Name> for TokioThreadpoolGaiResolver {
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type Response = GaiAddrs;
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type Error = io::Error;
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type Future = TokioThreadpoolGaiFuture;
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fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), io::Error>> {
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Poll::Ready(Ok(()))
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}
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fn call(&mut self, name: Name) -> Self::Future {
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TokioThreadpoolGaiFuture { name }
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}
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}
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#[cfg(feature = "runtime")]
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impl Future for TokioThreadpoolGaiFuture {
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type Output = Result<GaiAddrs, io::Error>;
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fn poll(self: Pin<&mut Self>, _cx: &mut task::Context<'_>) -> Poll<Self::Output> {
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match ready!(tokio_executor::threadpool::blocking(|| (
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self.name.as_str(),
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0
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)
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.to_socket_addrs()))
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{
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Ok(Ok(iter)) => Poll::Ready(Ok(GaiAddrs {
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inner: IpAddrs { iter },
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})),
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Ok(Err(e)) => Poll::Ready(Err(e)),
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// a BlockingError, meaning not on a tokio_executor::threadpool :(
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Err(e) => Poll::Ready(Err(io::Error::new(io::ErrorKind::Other, e))),
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}
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}
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}
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*/
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mod sealed {
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use super::{SocketAddr, Name};
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use crate::common::{task, Future, Poll};
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use tower_service::Service;
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// "Trait alias" for `Service<Name, Response = Addrs>`
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pub trait Resolve {
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type Addrs: Iterator<Item = SocketAddr>;
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type Error: Into<Box<dyn std::error::Error + Send + Sync>>;
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type Future: Future<Output = Result<Self::Addrs, Self::Error>>;
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fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>>;
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fn resolve(&mut self, name: Name) -> Self::Future;
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}
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impl<S> Resolve for S
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where
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S: Service<Name>,
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S::Response: Iterator<Item = SocketAddr>,
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S::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
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{
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type Addrs = S::Response;
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type Error = S::Error;
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type Future = S::Future;
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fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
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Service::poll_ready(self, cx)
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}
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fn resolve(&mut self, name: Name) -> Self::Future {
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Service::call(self, name)
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}
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}
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}
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pub(super) async fn resolve<R>(resolver: &mut R, name: Name) -> Result<R::Addrs, R::Error>
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where
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R: Resolve,
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{
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futures_util::future::poll_fn(|cx| resolver.poll_ready(cx)).await?;
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resolver.resolve(name).await
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use std::net::{Ipv4Addr, Ipv6Addr};
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#[test]
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fn test_ip_addrs_split_by_preference() {
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let ip_v4 = Ipv4Addr::new(127, 0, 0, 1);
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let ip_v6 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
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let v4_addr = (ip_v4, 80).into();
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let v6_addr = (ip_v6, 80).into();
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let (mut preferred, mut fallback) = SocketAddrs {
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iter: vec![v4_addr, v6_addr].into_iter(),
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}
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.split_by_preference(None, None);
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assert!(preferred.next().unwrap().is_ipv4());
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assert!(fallback.next().unwrap().is_ipv6());
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let (mut preferred, mut fallback) = SocketAddrs {
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iter: vec![v6_addr, v4_addr].into_iter(),
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}
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.split_by_preference(None, None);
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assert!(preferred.next().unwrap().is_ipv6());
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assert!(fallback.next().unwrap().is_ipv4());
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let (mut preferred, mut fallback) = SocketAddrs {
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iter: vec![v4_addr, v6_addr].into_iter(),
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}
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.split_by_preference(Some(ip_v4), Some(ip_v6));
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assert!(preferred.next().unwrap().is_ipv4());
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assert!(fallback.next().unwrap().is_ipv6());
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let (mut preferred, mut fallback) = SocketAddrs {
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iter: vec![v6_addr, v4_addr].into_iter(),
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}
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.split_by_preference(Some(ip_v4), Some(ip_v6));
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assert!(preferred.next().unwrap().is_ipv6());
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assert!(fallback.next().unwrap().is_ipv4());
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let (mut preferred, fallback) = SocketAddrs {
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iter: vec![v4_addr, v6_addr].into_iter(),
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}
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.split_by_preference(Some(ip_v4), None);
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assert!(preferred.next().unwrap().is_ipv4());
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assert!(fallback.is_empty());
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let (mut preferred, fallback) = SocketAddrs {
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iter: vec![v4_addr, v6_addr].into_iter(),
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}
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.split_by_preference(None, Some(ip_v6));
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assert!(preferred.next().unwrap().is_ipv6());
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assert!(fallback.is_empty());
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}
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#[test]
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fn test_name_from_str() {
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const DOMAIN: &str = "test.example.com";
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let name = Name::from_str(DOMAIN).expect("Should be a valid domain");
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assert_eq!(name.as_str(), DOMAIN);
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assert_eq!(name.to_string(), DOMAIN);
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}
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}
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