Fix peer connect race

src/onion_messenger.rs

@@ -29,7 +29,8 @@ use std::io::Cursor;
 use std::marker::Copy;
 use std::str::FromStr;
 use tokio::sync::mpsc::{channel, Receiver, Sender};
-use tokio::{select, time, time::Duration, time::Interval};
+use tokio::time::{sleep, timeout, Duration, Interval};
+use tokio::{select, time};
 use tonic_lnd::lnrpc::ChanInfoRequest;
 use tonic_lnd::Client;
 use tonic_lnd::{
@@ -331,7 +332,26 @@ async fn lookup_onion_support(pubkey: &PublicKey, client: &mut tonic_lnd::Lightn
                     continue;
                 }
 
-                return features_support_onion_messages(&peer.features);
+                // Sometimes if the connection to the peer is very new, we have to wait for the
+                // features map to populate as non-empty.
+                let check_empty_timeout = 5;
+                let features = match timeout(
+                    Duration::from_secs(check_empty_timeout),
+                    check_empty_features(pubkey, client.clone()),
+                )
+                .await
+                {
+                    Ok(features) => features,
+                    Err(_) => {
+                        warn!(
+                            "Did not get non-empty feature set from peer {} set in {} seconds.",
+                            peer.pub_key, check_empty_timeout
+                        );
+                        peer.features
+                    }
+                };
+
+                return features_support_onion_messages(&features);
             }
 
             warn!("Peer {pubkey} not found in current set of peers, assuming no onion support.");
@@ -344,6 +364,39 @@ async fn lookup_onion_support(pubkey: &PublicKey, client: &mut tonic_lnd::Lightn
     }
 }
 
+// check_empty_features repeatedly looks up the peer's feature set until it returns a non-empty
+// map. Sometimes if a peer is new, LND needs a little time to update the feature set.
+async fn check_empty_features(
+    pubkey: &PublicKey,
+    mut client: LightningClient,
+) -> HashMap<u32, tonic_lnd::lnrpc::Feature> {
+    loop {
+        match client
+            .list_peers(tonic_lnd::lnrpc::ListPeersRequest {
+                latest_error: false,
+            })
+            .await
+        {
+            Ok(peers) => {
+                for peer in peers.into_inner().peers {
+                    if peer.pub_key != pubkey.to_string() {
+                        continue;
+                    }
+
+                    if !peer.features.is_empty() {
+                        return peer.features;
+                    }
+                }
+            }
+            Err(_) => {
+                warn!("error connecting to listpeers");
+                continue;
+            }
+        };
+        sleep(Duration::from_millis(500)).await;
+    }
+}
+
 #[derive(Debug)]
 /// ProducerError represents the exit of a producing loop.
 enum ProducerError {