tor-chanmgr: Handle IO errora in the new style

Two ? in the tests become expects, which will do.  That avoids having
to construct a proper error with context here.

crates/tor-chanmgr/src/builder.rs

@@ -1,5 +1,6 @@
 //! Implement a concrete type to build channels.
 
+use std::io;
 use std::sync::Mutex;
 
 use crate::{event::ChanMgrEventSender, Error};
@@ -81,8 +82,13 @@ impl<R: Runtime> ChanBuilder<R> {
                 .record_attempt();
         }
 
+        let map_ioe = |ioe: io::Error| Error::Io {
+            peer: *addr,
+            source: ioe.into(),
+        };
+
         // Establish a TCP connection.
-        let stream = self.runtime.connect(addr).await?;
+        let stream = self.runtime.connect(addr).await.map_err(map_ioe)?;
 
         {
             self.event_sender
@@ -95,10 +101,12 @@ impl<R: Runtime> ChanBuilder<R> {
         let tls = self
             .tls_connector
             .negotiate_unvalidated(stream, "ignored")
-            .await?;
+            .await
+            .map_err(map_ioe)?;
 
         let peer_cert = tls
-            .peer_certificate()?
+            .peer_certificate()
+            .map_err(map_ioe)?
             .ok_or(Error::Internal("TLS connection with no peer certificate"))?;
 
         {
@@ -208,9 +216,11 @@ mod test {
                 async {
                     // relay-side: accept the channel
                     // (and pretend to know what we're doing).
-                    let (mut con, addr) = lis.accept().await?;
+                    let (mut con, addr) = lis.accept().await.expect("accept failed");
                     assert_eq!(client_addr, addr.ip());
-                    crate::testing::answer_channel_req(&mut con).await?;
+                    crate::testing::answer_channel_req(&mut con)
+                        .await
+                        .expect("answer failed");
                     Ok(con)
                 }
             );

crates/tor-chanmgr/src/err.rs

@@ -1,5 +1,6 @@
 //! Declare error types for tor-chanmgr
 
+use std::net::SocketAddr;
 use std::sync::Arc;
 
 use futures::task::SpawnError;
@@ -25,9 +26,16 @@ pub enum Error {
     #[error("Protocol error while opening a channel: {0}")]
     Proto(#[from] tor_proto::Error),
 
-    /// A protocol error while making a channel
-    #[error("I/O error while opening a channel: {0}")]
-    Io(#[source] Arc<std::io::Error>),
+    /// Network IO error or TLS error
+    #[error("Network IO error, or TLS error, talking to {peer}")]
+    Io {
+        /// Who we were talking to
+        peer: SocketAddr,
+
+        /// What happened.  Might be some TLS library error wrapped up in io::Error
+        #[source]
+        source: Arc<std::io::Error>,
+    },
 
     /// Unable to spawn task
     #[error("unable to spawn task")]
@@ -55,9 +63,3 @@ impl<T> From<std::sync::PoisonError<T>> for Error {
         Error::Internal("Thread failed while holding lock")
     }
 }
-
-impl From<std::io::Error> for Error {
-    fn from(e: std::io::Error) -> Error {
-        Error::Io(Arc::new(e))
-    }
-}