fix(ping): Fix panic in WASM caused by retrying on dial upgrade errors

This PR workarounds async-rs/futures-timer#74 issue.

Fixes libp2p#5442

Pull-Request: libp2p#5447.

Author: oblique

protocols/ping/CHANGELOG.md

@@ -3,6 +3,9 @@
 - Use `web-time` instead of `instant`.
   See [PR 5347](https://github.com/libp2p/rust-libp2p/pull/5347).
 
+- Fix panic in WASM caused by retrying on dial upgrade errors.
+  See [PR 5447](https://github.com/libp2p/rust-libp2p/pull/5447).
+
 ## 0.44.1
 
 - Impose `Sync` on `ping::Failure::Other`.

protocols/ping/src/handler.rs

@@ -184,6 +184,18 @@ impl Handler {
     ) {
         self.outbound = None; // Request a new substream on the next `poll`.
 
+        // Timer is already polled and expired before substream request is initiated
+        // and will be polled again later on in our `poll` because we reset `self.outbound`.
+        //
+        // `futures-timer` allows an expired timer to be polled again and returns
+        // immediately `Poll::Ready`. However in its WASM implementation there is
+        // a bug that causes the expired timer to panic.
+        // This is a workaround until a proper fix is merged and released.
+        // See libp2p/rust-libp2p#5447 for more info.
+        //
+        // TODO: remove when async-rs/futures-timer#74 gets merged.
+        self.interval.reset(Duration::new(0, 0));
+
         let error = match error {
             StreamUpgradeError::NegotiationFailed => {
                 debug_assert_eq!(self.state, State::Active);