libp2p: revise published address count/selection

1 files changed, 12 insertions, 3 deletions

diff --git a/src/transport/libp2p/mod.rs b/src/transport/libp2p/mod.rs
index 6032891..2ad07e5 100644
--- a/src/transport/libp2p/mod.rs
+++ b/src/transport/libp2p/mod.rs
@@ -145,6 +145,11 @@ const MIN_RATE: u64 = 1 << 20;
 const READS: usize = 32;
 /// Addresses kept per peer, and peers with addresses at most.
 const ADDRESSES_PER_PEER: usize = 8;
+/// Of this node's own, the direct ones (the best first) and those through relays it
+/// publishes at most (`local_addresses`): a node listening everywhere has many direct
+/// ones, and those through a relay are what reaches it from behind a NAT.
+const PUBLISHED_DIRECT: usize = 4;
+const PUBLISHED_RELAYED: usize = 2;
 const MAX_PEERS: usize = 4096;
 
 /// A relayed connection (circuit) through this node lasts at most this long and carries
@@ -363,20 +368,24 @@ impl Transport for Libp2pTransport {
     }
 
     /// Where we can be reached, each with our peer ID: the announced addresses, or else
-    /// those we listen on (`published`), and those through relays. A relay adds each
-    /// direct one again, ending in `/p2p-circuit`: where to reserve a slot.
+    /// those we listen on (`published`), and those through relays; at most
+    /// `PUBLISHED_DIRECT` and `PUBLISHED_RELAYED` of them, so the direct ones never
+    /// crowd out the relayed ones. A relay adds each direct one again, ending in
+    /// `/p2p-circuit`: where to reserve a slot.
     fn local_addresses(&self) -> Vec<String> {
         let book = lock(&self.book);
         let direct: Vec<Multiaddr> = book
             .direct()
             .into_iter()
             .filter_map(|address| address.with_p2p(self.peer_id).ok())
+            .take(PUBLISHED_DIRECT)
             .collect();
         let relayed = book
             .listening
             .iter()
             .filter(|address| is_relayed(address))
-            .filter_map(|address| address.clone().with_p2p(self.peer_id).ok());
+            .filter_map(|address| address.clone().with_p2p(self.peer_id).ok())
+            .take(PUBLISHED_RELAYED);
         let offers: Vec<Multiaddr> = if book.serving {
             direct
                 .iter()