fix: make DNS resolution async (#8743)

This commit adds a new function that is an asynchronous version of
`resolve_addr` using `tokio::net::lookup_host`, and accordingly, renames
the synchronous version to `resolve_addr_sync`.
This allows async ops to resolve hosts with non-blocking.

runtime/ops/net.rs

@@ -4,6 +4,7 @@ use crate::ops::io::StreamResource;
 use crate::ops::io::StreamResourceHolder;
 use crate::permissions::Permissions;
 use crate::resolve_addr::resolve_addr;
+use crate::resolve_addr::resolve_addr_sync;
 use deno_core::error::bad_resource;
 use deno_core::error::bad_resource_id;
 use deno_core::error::custom_error;
@@ -205,7 +206,7 @@ async fn op_datagram_send(
         s.borrow::<Permissions>()
           .check_net(&args.hostname, args.port)?;
       }
-      let addr = resolve_addr(&args.hostname, args.port)?;
+      let addr = resolve_addr(&args.hostname, args.port).await?;
       poll_fn(move |cx| {
         let mut state = state.borrow_mut();
         let resource = state
@@ -272,7 +273,7 @@ async fn op_connect(
           .borrow::<Permissions>()
           .check_net(&args.hostname, args.port)?;
       }
-      let addr = resolve_addr(&args.hostname, args.port)?;
+      let addr = resolve_addr(&args.hostname, args.port).await?;
       let tcp_stream = TcpStream::connect(&addr).await?;
       let local_addr = tcp_stream.local_addr()?;
       let remote_addr = tcp_stream.peer_addr()?;
@@ -505,7 +506,7 @@ fn op_listen(
         }
         permissions.check_net(&args.hostname, args.port)?;
       }
-      let addr = resolve_addr(&args.hostname, args.port)?;
+      let addr = resolve_addr_sync(&args.hostname, args.port)?;
       let (rid, local_addr) = if transport == "tcp" {
         listen_tcp(state, addr)?
       } else {

runtime/ops/tls.rs

@@ -3,6 +3,7 @@
 use super::io::{StreamResource, StreamResourceHolder};
 use crate::permissions::Permissions;
 use crate::resolve_addr::resolve_addr;
+use crate::resolve_addr::resolve_addr_sync;
 use deno_core::error::bad_resource;
 use deno_core::error::bad_resource_id;
 use deno_core::error::custom_error;
@@ -160,7 +161,7 @@ async fn op_connect_tls(
     domain.push_str("localhost");
   }
 
-  let addr = resolve_addr(&args.hostname, args.port)?;
+  let addr = resolve_addr(&args.hostname, args.port).await?;
   let tcp_stream = TcpStream::connect(&addr).await?;
   let local_addr = tcp_stream.local_addr()?;
   let remote_addr = tcp_stream.peer_addr()?;
@@ -334,7 +335,7 @@ fn op_listen_tls(
     .set_single_cert(load_certs(&cert_file)?, load_keys(&key_file)?.remove(0))
     .expect("invalid key or certificate");
   let tls_acceptor = TlsAcceptor::from(Arc::new(config));
-  let addr = resolve_addr(&args.hostname, args.port)?;
+  let addr = resolve_addr_sync(&args.hostname, args.port)?;
   let std_listener = std::net::TcpListener::bind(&addr)?;
   let listener = TcpListener::from_std(std_listener)?;
   let local_addr = listener.local_addr()?;

runtime/resolve_addr.rs

@@ -1,29 +1,45 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
 use deno_core::error::AnyError;
+use deno_core::error::Context;
 use std::net::SocketAddr;
 use std::net::ToSocketAddrs;
+use tokio::net::lookup_host;
 
-/// Resolve network address. Returns a future.
+/// Resolve network address *asynchronously*.
-pub fn resolve_addr(hostname: &str, port: u16) -> Result<SocketAddr, AnyError> {
+pub async fn resolve_addr(
+  hostname: &str,
+  port: u16,
+) -> Result<SocketAddr, AnyError> {
+  let addr_port_pair = make_addr_port_pair(hostname, port);
+  lookup_host(addr_port_pair)
+    .await?
+    .next()
+    .context("No resolved address found")
+}
+
+/// Resolve network address *synchronously*.
+pub fn resolve_addr_sync(
+  hostname: &str,
+  port: u16,
+) -> Result<SocketAddr, AnyError> {
+  let addr_port_pair = make_addr_port_pair(hostname, port);
+  addr_port_pair
+    .to_socket_addrs()?
+    .next()
+    .context("No resolved address found")
+}
+
+fn make_addr_port_pair(hostname: &str, port: u16) -> (&str, u16) {
   // Default to localhost if given just the port. Example: ":80"
-  let addr: &str = if !hostname.is_empty() {
+  if hostname.is_empty() {
-    &hostname
+    return ("0.0.0.0", port);
-  } else {
+  }
-    "0.0.0.0"
-  };
 
   // If this looks like an ipv6 IP address. Example: "[2001:db8::1]"
   // Then we remove the brackets.
-  let addr = if addr.starts_with('[') && addr.ends_with(']') {
+  let addr = hostname.trim_start_matches('[').trim_end_matches(']');
-    let l = addr.len() - 1;
+  (addr, port)
-    addr.get(1..l).unwrap()
-  } else {
-    addr
-  };
-  let addr_port_pair = (addr, port);
-  let mut iter = addr_port_pair.to_socket_addrs()?;
-  Ok(iter.next().unwrap())
 }
 
 #[cfg(test)]
@@ -34,39 +50,85 @@ mod tests {
   use std::net::SocketAddrV4;
   use std::net::SocketAddrV6;
 
-  #[test]
+  #[tokio::test]
-  fn resolve_addr1() {
+  async fn resolve_addr1() {
     let expected =
       SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 80));
-    let actual = resolve_addr("127.0.0.1", 80).unwrap();
+    let actual = resolve_addr("127.0.0.1", 80).await.unwrap();
     assert_eq!(actual, expected);
   }
 
-  #[test]
+  #[tokio::test]
-  fn resolve_addr2() {
+  async fn resolve_addr2() {
     let expected =
       SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(0, 0, 0, 0), 80));
-    let actual = resolve_addr("", 80).unwrap();
+    let actual = resolve_addr("", 80).await.unwrap();
     assert_eq!(actual, expected);
   }
 
-  #[test]
+  #[tokio::test]
-  fn resolve_addr3() {
+  async fn resolve_addr3() {
     let expected =
       SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(192, 0, 2, 1), 25));
-    let actual = resolve_addr("192.0.2.1", 25).unwrap();
+    let actual = resolve_addr("192.0.2.1", 25).await.unwrap();
     assert_eq!(actual, expected);
   }
 
-  #[test]
+  #[tokio::test]
-  fn resolve_addr_ipv6() {
+  async fn resolve_addr_ipv6() {
     let expected = SocketAddr::V6(SocketAddrV6::new(
       Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1),
       8080,
       0,
       0,
     ));
-    let actual = resolve_addr("[2001:db8::1]", 8080).unwrap();
+    let actual = resolve_addr("[2001:db8::1]", 8080).await.unwrap();
     assert_eq!(actual, expected);
   }
+
+  #[tokio::test]
+  async fn resolve_addr_err() {
+    assert!(resolve_addr("INVALID ADDR", 1234).await.is_err());
+  }
+
+  #[test]
+  fn resolve_addr_sync1() {
+    let expected =
+      SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 80));
+    let actual = resolve_addr_sync("127.0.0.1", 80).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr_sync2() {
+    let expected =
+      SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(0, 0, 0, 0), 80));
+    let actual = resolve_addr_sync("", 80).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr_sync3() {
+    let expected =
+      SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(192, 0, 2, 1), 25));
+    let actual = resolve_addr_sync("192.0.2.1", 25).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr_sync_ipv6() {
+    let expected = SocketAddr::V6(SocketAddrV6::new(
+      Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1),
+      8080,
+      0,
+      0,
+    ));
+    let actual = resolve_addr_sync("[2001:db8::1]", 8080).unwrap();
+    assert_eq!(actual, expected);
+  }
+
+  #[test]
+  fn resolve_addr_sync_err() {
+    assert!(resolve_addr_sync("INVALID ADDR", 1234).is_err());
+  }
 }