fix: whitelist nebula crawlers

CHANGELOG.md

@@ -67,6 +67,8 @@
 
 - [#6430](https://github.com/ChainSafe/forest/issues/6430) Fixed a panic when syncing from genesis on the calibration network.
 
+- [#6456](https://github.com/ChainSafe/forest/pull/6456) Whitelisted nebula and hermes crawlers.
+
 ## Forest v0.30.5 "Dulce de Leche"
 
 Non-mandatory release supporting new API methods and addressing a critical panic issue.

src/libp2p/peer_manager.rs

@@ -220,9 +220,18 @@ impl PeerManager {
         if self.is_peer_protected(&peer) {
             return;
         }
+
+        let user_agent = get_user_agent(&peer);
+        // Whitelist crawlers
+        if let Some(ua) = &user_agent
+            && is_crawler(ua)
+        {
+            tracing::debug!("whitelisted crawler peer {peer} with user agent {ua}");
+            return;
+        }
+
         let mut locked = self.peer_ban_list.write().await;
         locked.insert(peer, duration.and_then(|d| Instant::now().checked_add(d)));
-        let user_agent = get_user_agent(&peer);
         if let Err(e) = self
             .peer_ops_tx
             .send_async(PeerOperation::Ban {
@@ -333,3 +342,25 @@ pub enum PeerOperation {
     },
     Unban(PeerId),
 }
+
+fn is_crawler(user_agent: impl AsRef<str>) -> bool {
+    let ua = user_agent.as_ref();
+    ua.starts_with("nebula/") || ua.starts_with("hermes")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_is_crawler() {
+        assert!(is_crawler("nebula/"));
+        assert!(is_crawler("nebula/1.0"));
+        assert!(is_crawler("hermes"));
+        assert!(is_crawler("hermes/1.0"));
+
+        assert!(!is_crawler("forest"));
+        assert!(!is_crawler("lotus"));
+        assert!(!is_crawler("venus"));
+    }
+}