sync with neighbours

1 files changed, 13 insertions, 1 deletions

diff --git a/src/swarm/sync.rs b/src/swarm/sync.rs
index e05d275..b8d16aa 100644
--- a/src/swarm/sync.rs
+++ b/src/swarm/sync.rs
@@ -85,6 +85,14 @@ async fn deliver_sync_to_peer(state: &AppState, peer: &str) -> Result<()> {
             return Ok(());
         }
 
+        if peer_state.sync.state.their_heads.is_none()
+            && !crate::swarm::topology::is_neighbour(state, peer)
+        {
+            // We only answer peers that aren't our neighbours.
+            trace!("Not opening sync with a peer that isn't our neighbour");
+            return Ok(());
+        }
+
         swarm_id.clone()
     };
 
@@ -444,8 +452,12 @@ pub(crate) async fn run_sync_worker(state: AppState, mut rx: mpsc::UnboundedRece
                 peers_guard.keys().cloned().collect()
             };
 
+            // Our own changes go to our neighbours; they pass them on. Others only get
+            // answers to what they send us.
             for peer in peer_keys {
-                if peer_swarm(&state, &peer).await.is_some() {
+                if peer_swarm(&state, &peer).await.is_some()
+                    && crate::swarm::topology::is_neighbour(&state, &peer)
+                {
                     dirty_peers.insert(peer);
                 }
             }