1 files changed, 425 insertions, 0 deletions
diff --git a/third_party/rust/hyper/src/client/connect/dns.rs b/third_party/rust/hyper/src/client/connect/dns.rs
new file mode 100644
index 0000000000..e4465078b3
--- /dev/null
+++ b/third_party/rust/hyper/src/client/connect/dns.rs
@@ -0,0 +1,425 @@
+//! DNS Resolution used by the `HttpConnector`.
+//!
+//! This module contains:
+//!
+//! - A [`GaiResolver`](GaiResolver) that is the default resolver for the
+//!   `HttpConnector`.
+//! - The `Name` type used as an argument to custom resolvers.
+//!
+//! # Resolvers are `Service`s
+//!
+//! A resolver is just a
+//! `Service<Name, Response = impl Iterator<Item = SocketAddr>>`.
+//!
+//! A simple resolver that ignores the name and always returns a specific
+//! address:
+//!
+//! ```rust,ignore
+//! use std::{convert::Infallible, iter, net::SocketAddr};
+//!
+//! let resolver = tower::service_fn(|_name| async {
+//!     Ok::<_, Infallible>(iter::once(SocketAddr::from(([127, 0, 0, 1], 8080))))
+//! });
+//! ```
+use std::error::Error;
+use std::future::Future;
+use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
+use std::pin::Pin;
+use std::str::FromStr;
+use std::task::{self, Poll};
+use std::{fmt, io, vec};
+
+use tokio::task::JoinHandle;
+use tower_service::Service;
+use tracing::debug;
+
+pub(super) use self::sealed::Resolve;
+
+/// A domain name to resolve into IP addresses.
+#[derive(Clone, Hash, Eq, PartialEq)]
+pub struct Name {
+    host: Box<str>,
+}
+
+/// A resolver using blocking `getaddrinfo` calls in a threadpool.
+#[derive(Clone)]
+pub struct GaiResolver {
+    _priv: (),
+}
+
+/// An iterator of IP addresses returned from `getaddrinfo`.
+pub struct GaiAddrs {
+    inner: SocketAddrs,
+}
+
+/// A future to resolve a name returned by `GaiResolver`.
+pub struct GaiFuture {
+    inner: JoinHandle<Result<SocketAddrs, io::Error>>,
+}
+
+impl Name {
+    pub(super) fn new(host: Box<str>) -> Name {
+        Name { host }
+    }
+
+    /// View the hostname as a string slice.
+    pub fn as_str(&self) -> &str {
+        &self.host
+    }
+}
+
+impl fmt::Debug for Name {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.host, f)
+    }
+}
+
+impl fmt::Display for Name {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.host, f)
+    }
+}
+
+impl FromStr for Name {
+    type Err = InvalidNameError;
+
+    fn from_str(host: &str) -> Result<Self, Self::Err> {
+        // Possibly add validation later
+        Ok(Name::new(host.into()))
+    }
+}
+
+/// Error indicating a given string was not a valid domain name.
+#[derive(Debug)]
+pub struct InvalidNameError(());
+
+impl fmt::Display for InvalidNameError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("Not a valid domain name")
+    }
+}
+
+impl Error for InvalidNameError {}
+
+impl GaiResolver {
+    /// Construct a new `GaiResolver`.
+    pub fn new() -> Self {
+        GaiResolver { _priv: () }
+    }
+}
+
+impl Service<Name> for GaiResolver {
+    type Response = GaiAddrs;
+    type Error = io::Error;
+    type Future = GaiFuture;
+
+    fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn call(&mut self, name: Name) -> Self::Future {
+        let blocking = tokio::task::spawn_blocking(move || {
+            debug!("resolving host={:?}", name.host);
+            (&*name.host, 0)
+                .to_socket_addrs()
+                .map(|i| SocketAddrs { iter: i })
+        });
+
+        GaiFuture { inner: blocking }
+    }
+}
+
+impl fmt::Debug for GaiResolver {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("GaiResolver")
+    }
+}
+
+impl Future for GaiFuture {
+    type Output = Result<GaiAddrs, io::Error>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        Pin::new(&mut self.inner).poll(cx).map(|res| match res {
+            Ok(Ok(addrs)) => Ok(GaiAddrs { inner: addrs }),
+            Ok(Err(err)) => Err(err),
+            Err(join_err) => {
+                if join_err.is_cancelled() {
+                    Err(io::Error::new(io::ErrorKind::Interrupted, join_err))
+                } else {
+                    panic!("gai background task failed: {:?}", join_err)
+                }
+            }
+        })
+    }
+}
+
+impl fmt::Debug for GaiFuture {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("GaiFuture")
+    }
+}
+
+impl Drop for GaiFuture {
+    fn drop(&mut self) {
+        self.inner.abort();
+    }
+}
+
+impl Iterator for GaiAddrs {
+    type Item = SocketAddr;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+}
+
+impl fmt::Debug for GaiAddrs {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("GaiAddrs")
+    }
+}
+
+pub(super) struct SocketAddrs {
+    iter: vec::IntoIter<SocketAddr>,
+}
+
+impl SocketAddrs {
+    pub(super) fn new(addrs: Vec<SocketAddr>) -> Self {
+        SocketAddrs {
+            iter: addrs.into_iter(),
+        }
+    }
+
+    pub(super) fn try_parse(host: &str, port: u16) -> Option<SocketAddrs> {
+        if let Ok(addr) = host.parse::<Ipv4Addr>() {
+            let addr = SocketAddrV4::new(addr, port);
+            return Some(SocketAddrs {
+                iter: vec![SocketAddr::V4(addr)].into_iter(),
+            });
+        }
+        if let Ok(addr) = host.parse::<Ipv6Addr>() {
+            let addr = SocketAddrV6::new(addr, port, 0, 0);
+            return Some(SocketAddrs {
+                iter: vec![SocketAddr::V6(addr)].into_iter(),
+            });
+        }
+        None
+    }
+
+    #[inline]
+    fn filter(self, predicate: impl FnMut(&SocketAddr) -> bool) -> SocketAddrs {
+        SocketAddrs::new(self.iter.filter(predicate).collect())
+    }
+
+    pub(super) fn split_by_preference(
+        self,
+        local_addr_ipv4: Option<Ipv4Addr>,
+        local_addr_ipv6: Option<Ipv6Addr>,
+    ) -> (SocketAddrs, SocketAddrs) {
+        match (local_addr_ipv4, local_addr_ipv6) {
+            (Some(_), None) => (self.filter(SocketAddr::is_ipv4), SocketAddrs::new(vec![])),
+            (None, Some(_)) => (self.filter(SocketAddr::is_ipv6), SocketAddrs::new(vec![])),
+            _ => {
+                let preferring_v6 = self
+                    .iter
+                    .as_slice()
+                    .first()
+                    .map(SocketAddr::is_ipv6)
+                    .unwrap_or(false);
+
+                let (preferred, fallback) = self
+                    .iter
+                    .partition::<Vec<_>, _>(|addr| addr.is_ipv6() == preferring_v6);
+
+                (SocketAddrs::new(preferred), SocketAddrs::new(fallback))
+            }
+        }
+    }
+
+    pub(super) fn is_empty(&self) -> bool {
+        self.iter.as_slice().is_empty()
+    }
+
+    pub(super) fn len(&self) -> usize {
+        self.iter.as_slice().len()
+    }
+}
+
+impl Iterator for SocketAddrs {
+    type Item = SocketAddr;
+    #[inline]
+    fn next(&mut self) -> Option<SocketAddr> {
+        self.iter.next()
+    }
+}
+
+/*
+/// A resolver using `getaddrinfo` calls via the `tokio_executor::threadpool::blocking` API.
+///
+/// Unlike the `GaiResolver` this will not spawn dedicated threads, but only works when running on the
+/// multi-threaded Tokio runtime.
+#[cfg(feature = "runtime")]
+#[derive(Clone, Debug)]
+pub struct TokioThreadpoolGaiResolver(());
+
+/// The future returned by `TokioThreadpoolGaiResolver`.
+#[cfg(feature = "runtime")]
+#[derive(Debug)]
+pub struct TokioThreadpoolGaiFuture {
+    name: Name,
+}
+
+#[cfg(feature = "runtime")]
+impl TokioThreadpoolGaiResolver {
+    /// Creates a new DNS resolver that will use tokio threadpool's blocking
+    /// feature.
+    ///
+    /// **Requires** its futures to be run on the threadpool runtime.
+    pub fn new() -> Self {
+        TokioThreadpoolGaiResolver(())
+    }
+}
+
+#[cfg(feature = "runtime")]
+impl Service<Name> for TokioThreadpoolGaiResolver {
+    type Response = GaiAddrs;
+    type Error = io::Error;
+    type Future = TokioThreadpoolGaiFuture;
+
+    fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn call(&mut self, name: Name) -> Self::Future {
+        TokioThreadpoolGaiFuture { name }
+    }
+}
+
+#[cfg(feature = "runtime")]
+impl Future for TokioThreadpoolGaiFuture {
+    type Output = Result<GaiAddrs, io::Error>;
+
+    fn poll(self: Pin<&mut Self>, _cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        match ready!(tokio_executor::threadpool::blocking(|| (
+            self.name.as_str(),
+            0
+        )
+            .to_socket_addrs()))
+        {
+            Ok(Ok(iter)) => Poll::Ready(Ok(GaiAddrs {
+                inner: IpAddrs { iter },
+            })),
+            Ok(Err(e)) => Poll::Ready(Err(e)),
+            // a BlockingError, meaning not on a tokio_executor::threadpool :(
+            Err(e) => Poll::Ready(Err(io::Error::new(io::ErrorKind::Other, e))),
+        }
+    }
+}
+*/
+
+mod sealed {
+    use super::{SocketAddr, Name};
+    use crate::common::{task, Future, Poll};
+    use tower_service::Service;
+
+    // "Trait alias" for `Service<Name, Response = Addrs>`
+    pub trait Resolve {
+        type Addrs: Iterator<Item = SocketAddr>;
+        type Error: Into<Box<dyn std::error::Error + Send + Sync>>;
+        type Future: Future<Output = Result<Self::Addrs, Self::Error>>;
+
+        fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>>;
+        fn resolve(&mut self, name: Name) -> Self::Future;
+    }
+
+    impl<S> Resolve for S
+    where
+        S: Service<Name>,
+        S::Response: Iterator<Item = SocketAddr>,
+        S::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
+    {
+        type Addrs = S::Response;
+        type Error = S::Error;
+        type Future = S::Future;
+
+        fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
+            Service::poll_ready(self, cx)
+        }
+
+        fn resolve(&mut self, name: Name) -> Self::Future {
+            Service::call(self, name)
+        }
+    }
+}
+
+pub(super) async fn resolve<R>(resolver: &mut R, name: Name) -> Result<R::Addrs, R::Error>
+where
+    R: Resolve,
+{
+    futures_util::future::poll_fn(|cx| resolver.poll_ready(cx)).await?;
+    resolver.resolve(name).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::net::{Ipv4Addr, Ipv6Addr};
+
+    #[test]
+    fn test_ip_addrs_split_by_preference() {
+        let ip_v4 = Ipv4Addr::new(127, 0, 0, 1);
+        let ip_v6 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
+        let v4_addr = (ip_v4, 80).into();
+        let v6_addr = (ip_v6, 80).into();
+
+        let (mut preferred, mut fallback) = SocketAddrs {
+            iter: vec![v4_addr, v6_addr].into_iter(),
+        }
+        .split_by_preference(None, None);
+        assert!(preferred.next().unwrap().is_ipv4());
+        assert!(fallback.next().unwrap().is_ipv6());
+
+        let (mut preferred, mut fallback) = SocketAddrs {
+            iter: vec![v6_addr, v4_addr].into_iter(),
+        }
+        .split_by_preference(None, None);
+        assert!(preferred.next().unwrap().is_ipv6());
+        assert!(fallback.next().unwrap().is_ipv4());
+
+        let (mut preferred, mut fallback) = SocketAddrs {
+            iter: vec![v4_addr, v6_addr].into_iter(),
+        }
+        .split_by_preference(Some(ip_v4), Some(ip_v6));
+        assert!(preferred.next().unwrap().is_ipv4());
+        assert!(fallback.next().unwrap().is_ipv6());
+
+        let (mut preferred, mut fallback) = SocketAddrs {
+            iter: vec![v6_addr, v4_addr].into_iter(),
+        }
+        .split_by_preference(Some(ip_v4), Some(ip_v6));
+        assert!(preferred.next().unwrap().is_ipv6());
+        assert!(fallback.next().unwrap().is_ipv4());
+
+        let (mut preferred, fallback) = SocketAddrs {
+            iter: vec![v4_addr, v6_addr].into_iter(),
+        }
+        .split_by_preference(Some(ip_v4), None);
+        assert!(preferred.next().unwrap().is_ipv4());
+        assert!(fallback.is_empty());
+
+        let (mut preferred, fallback) = SocketAddrs {
+            iter: vec![v4_addr, v6_addr].into_iter(),
+        }
+        .split_by_preference(None, Some(ip_v6));
+        assert!(preferred.next().unwrap().is_ipv6());
+        assert!(fallback.is_empty());
+    }
+
+    #[test]
+    fn test_name_from_str() {
+        const DOMAIN: &str = "test.example.com";
+        let name = Name::from_str(DOMAIN).expect("Should be a valid domain");
+        assert_eq!(name.as_str(), DOMAIN);
+        assert_eq!(name.to_string(), DOMAIN);
+    }
+}