Try again substreams that have failed in open in the past

lib/src/libp2p/peers.rs

@@ -1403,7 +1403,13 @@ where
     ) -> impl Iterator<Item = (&'_ PeerId, usize)> + '_ {
         self.unfulfilled_desired_outbound_substreams
             .iter()
-            .filter(move |((_, _), already_tried)| **already_tried == include_already_tried)
+            .filter(
+                move |((_, _), already_tried)| match (**already_tried, include_already_tried) {
+                    (false, _) => true,
+                    (true, true) => true,
+                    (true, false) => false,
+                },
+            )
             .map(|((peer_index, notifications_protocol_index), _)| {
                 (
                     &self.peers[*peer_index].peer_id,

lib/src/network/service.rs

@@ -929,11 +929,15 @@ where
 
         // Before returning the event, we check whether there is any desired outbound substream
         // to open.
+        // Note: we can't use a `while let` due to borrow checker errors.
         loop {
-            // Note: we can't use a `while let` due to borrow checker errors.
+            // Query the list of substreams that need to be opened.
+            // When a substream is refused by the remote, we make sure to mark it as "not desired"
+            // unless that substream really is supposed to be open. For this reason, substreams
+            // that have been tried in the past are also included in the list.
             let (peer_id, notifications_protocol_index) = match self
                 .inner
-                .unfulfilled_desired_outbound_substream(false)
+                .unfulfilled_desired_outbound_substream(true)
                 .next()
             {
                 Some((peer_id, idx)) => (peer_id.clone(), idx),

lib/src/network/service/notifications.rs

@@ -275,6 +275,11 @@ where
             }
 
             // Other protocol.
+            // These substreams are supposed to be openable but have been refused for some reason.
+            // As of the writing of this comment, a Substrate issue causes it to refuse
+            // transactions and GrandPa substreams if they are opened too quickly after the block
+            // announces substream.
+            // Do nothing, as the opening will be attempted again in the future.
             Err(_) => None,
 
             // Unrecognized protocol.

wasm-node/CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - Add support for the `ext_hashing_keccak_512_version_1` host function. ([#231](https://github.com/smol-dot/smoldot/pull/231))
 
+## Changed
+
+- When a full node refuses an outbound transactions or GrandPa substream even though a block announces substream has been established, smoldot now tries to reopen the failed substream. This bypasses a Substrate issue. ([#240](https://github.com/smol-dot/smoldot/pull/240))
+
 ## Fixed
 
 - Fix panic when the input data of a Wasm function call is larger than a Wasm page. ([#218](https://github.com/smol-dot/smoldot/pull/218))