Improve verbose errors for socket addresses

Moves the point of adding error context to the net::addr module so that we have access to the raw address input and can include it in the error message.

Author: Pascal Hertleif

src/net/addr.rs

@@ -1,11 +1,12 @@
+use std::future::Future;
 use std::mem;
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 use std::net::{SocketAddr, SocketAddrV4, SocketAddrV6};
 use std::pin::Pin;
-use std::future::Future;
 
 use crate::io;
 use crate::task::{spawn_blocking, Context, JoinHandle, Poll};
+use crate::utils::Context as ErrorContext;
 
 cfg_not_docs! {
  macro_rules! ret {
@@ -67,6 +68,18 @@ pub enum ToSocketAddrsFuture<I> {
  Done,
 }
 
+/// Wrap `std::io::Error` with additional message
+///
+/// Keeps the original error kind and stores the original I/O error as `source`.
+impl<T> ErrorContext for ToSocketAddrsFuture<T> {
+ fn context(self, message: impl Fn() -> String) -> Self {
+ match self {
+ ToSocketAddrsFuture::Ready(res) => ToSocketAddrsFuture::Ready(res.context(message)),
+ x => x,
+ }
+ }
+}
+
 impl<I: Iterator<Item = SocketAddr>> Future for ToSocketAddrsFuture<I> {
  type Output = io::Result<I>;
 
@@ -110,7 +123,9 @@ impl ToSocketAddrs for SocketAddrV4 {
  impl Future<Output = Self::Iter>,
  ToSocketAddrsFuture<Self::Iter>
  ) {
- SocketAddr::V4(*self).to_socket_addrs()
+ SocketAddr::V4(*self)
+ .to_socket_addrs()
+ .context(|| format!("could not resolve address `{}`", self))
  }
 }
 
@@ -123,7 +138,9 @@ impl ToSocketAddrs for SocketAddrV6 {
  impl Future<Output = Self::Iter>,
  ToSocketAddrsFuture<Self::Iter>
  ) {
- SocketAddr::V6(*self).to_socket_addrs()
+ SocketAddr::V6(*self)
+ .to_socket_addrs()
+ .context(|| format!("could not resolve address `{}`", self))
  }
 }
 
@@ -195,7 +212,9 @@ impl ToSocketAddrs for (&str, u16) {
 
  let host = host.to_string();
  let task = spawn_blocking(move || {
- std::net::ToSocketAddrs::to_socket_addrs(&(host.as_str(), port))
+ let addr = (host.as_str(), port);
+ std::net::ToSocketAddrs::to_socket_addrs(&addr)
+ .context(|| format!("could not resolve address `{:?}`", addr))
  });
  ToSocketAddrsFuture::Resolving(task)
  }
@@ -215,7 +234,10 @@ impl ToSocketAddrs for str {
  }
 
  let addr = self.to_string();
- let task = spawn_blocking(move || std::net::ToSocketAddrs::to_socket_addrs(addr.as_str()));
+ let task = spawn_blocking(move || {
+ std::net::ToSocketAddrs::to_socket_addrs(addr.as_str())
+ .context(|| format!("could not resolve address `{:?}`", addr))
+ });
  ToSocketAddrsFuture::Resolving(task)
  }
 }

src/net/tcp/listener.rs

@@ -8,7 +8,6 @@ use crate::net::driver::Watcher;
 use crate::net::{TcpStream, ToSocketAddrs};
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
-use crate::utils::Context as _;
 
 /// A TCP socket server, listening for connections.
 ///
@@ -78,8 +77,7 @@ impl TcpListener {
  let mut last_err = None;
  let addrs = addrs
  .to_socket_addrs()
- .await
- .context(|| String::from("could not resolve addresses"))?;
+ .await?;
 
  for addr in addrs {
  match mio::net::TcpListener::bind(&addr) {

src/net/tcp/stream.rs

@@ -74,8 +74,7 @@ impl TcpStream {
  let mut last_err = None;
  let addrs = addrs
  .to_socket_addrs()
- .await
- .context(|| String::from("could not resolve addresses"))?;
+ .await?;
 
  for addr in addrs {
  let res = spawn_blocking(move || {

src/net/udp/mod.rs

@@ -71,8 +71,7 @@ impl UdpSocket {
  let mut last_err = None;
  let addrs = addrs
  .to_socket_addrs()
- .await
- .context(|| String::from("could not resolve addresses"))?;
+ .await?;
 
  for addr in addrs {
  match mio::net::UdpSocket::bind(&addr) {

tests/verbose_errors.rs

@@ -1,4 +1,4 @@
-use async_std::{fs, task};
+use async_std::{fs, io, net::ToSocketAddrs, task};
 
 #[test]
 fn open_file() {
@@ -14,3 +14,18 @@ fn open_file() {
  }
  })
 }
+
+#[test]
+fn resolve_address() {
+ task::block_on(async {
+ let non_existing_addr = "ashjudlkahasdasdsikdhajik.asdasdasdasdasdasd.fjuiklashdbflasas:80";
+ let res: Result<_, io::Error> = non_existing_addr.to_socket_addrs().await;
+ match res {
+ Ok(_) => panic!("Found address with random name: We live in a simulation"),
+ Err(e) => assert_eq!(
+ "could not resolve address `\"ashjudlkahasdasdsikdhajik.asdasdasdasdasdasd.fjuiklashdbflasas:80\"`",
+ &format!("{}", e)
+ ),
+ }
+ })
+}