1 files changed, 116 insertions, 0 deletions
diff --git a/ext/fetch/dns.rs b/ext/fetch/dns.rs
new file mode 100644
index 000000000..9e21a4c34
--- /dev/null
+++ b/ext/fetch/dns.rs
@@ -0,0 +1,116 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+use std::future::Future;
+use std::io;
+use std::net::SocketAddr;
+use std::pin::Pin;
+use std::task::Poll;
+use std::task::{self};
+use std::vec;
+
+use hickory_resolver::error::ResolveError;
+use hickory_resolver::name_server::GenericConnector;
+use hickory_resolver::name_server::TokioRuntimeProvider;
+use hickory_resolver::AsyncResolver;
+use hyper_util::client::legacy::connect::dns::GaiResolver;
+use hyper_util::client::legacy::connect::dns::Name;
+use tokio::task::JoinHandle;
+use tower::Service;
+
+#[derive(Clone, Debug)]
+pub enum Resolver {
+  /// A resolver using blocking `getaddrinfo` calls in a threadpool.
+  Gai(GaiResolver),
+  /// hickory-resolver's userspace resolver.
+  Hickory(AsyncResolver<GenericConnector<TokioRuntimeProvider>>),
+}
+
+impl Default for Resolver {
+  fn default() -> Self {
+    Self::gai()
+  }
+}
+
+impl Resolver {
+  pub fn gai() -> Self {
+    Self::Gai(GaiResolver::new())
+  }
+
+  /// Create a [`AsyncResolver`] from system conf.
+  pub fn hickory() -> Result<Self, ResolveError> {
+    Ok(Self::Hickory(
+      hickory_resolver::AsyncResolver::tokio_from_system_conf()?,
+    ))
+  }
+
+  pub fn hickory_from_async_resolver(
+    resolver: AsyncResolver<GenericConnector<TokioRuntimeProvider>>,
+  ) -> Self {
+    Self::Hickory(resolver)
+  }
+}
+
+type SocketAddrs = vec::IntoIter<SocketAddr>;
+
+pub struct ResolveFut {
+  inner: JoinHandle<Result<SocketAddrs, io::Error>>,
+}
+
+impl Future for ResolveFut {
+  type Output = Result<SocketAddrs, 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(addrs),
+      Ok(Err(e)) => Err(e),
+      Err(join_err) => {
+        if join_err.is_cancelled() {
+          Err(io::Error::new(io::ErrorKind::Interrupted, join_err))
+        } else {
+          Err(io::Error::new(io::ErrorKind::Other, join_err))
+        }
+      }
+    })
+  }
+}
+
+impl Service<Name> for Resolver {
+  type Response = SocketAddrs;
+  type Error = io::Error;
+  type Future = ResolveFut;
+
+  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 task = match self {
+      Resolver::Gai(gai_resolver) => {
+        let mut resolver = gai_resolver.clone();
+        tokio::spawn(async move {
+          let result = resolver.call(name).await?;
+          let x: Vec<_> = result.into_iter().collect();
+          let iter: SocketAddrs = x.into_iter();
+          Ok(iter)
+        })
+      }
+      Resolver::Hickory(async_resolver) => {
+        let resolver = async_resolver.clone();
+        tokio::spawn(async move {
+          let result = resolver.lookup_ip(name.as_str()).await?;
+
+          let x: Vec<_> =
+            result.into_iter().map(|x| SocketAddr::new(x, 0)).collect();
+          let iter: SocketAddrs = x.into_iter();
+          Ok(iter)
+        })
+      }
+    };
+    ResolveFut { inner: task }
+  }
+}