From f1a22910374e2f955641c9886b74eed189b27b97 Mon Sep 17 00:00:00 2001
From: tuyennhv <tuyen@chainsafe.io>
Date: Sun, 13 Aug 2023 00:08:27 +0700
Subject: [PATCH] feat: limit incoming connections to lodestar (#5860)

* feat: limit incoming connections to lodestar

* chore: revise comment
---
 packages/beacon-node/src/network/libp2p/index.ts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/packages/beacon-node/src/network/libp2p/index.ts b/packages/beacon-node/src/network/libp2p/index.ts
index 4540cae67974..bd96de0e6bbf 100644
--- a/packages/beacon-node/src/network/libp2p/index.ts
+++ b/packages/beacon-node/src/network/libp2p/index.ts
@@ -75,6 +75,10 @@ export async function createNodeJsLibp2p(
     transports: [
       tcp({
         maxConnections: networkOpts.maxPeers,
+        // socket option: the maximum length of the queue of pending connections
+        // https://nodejs.org/dist/latest-v18.x/docs/api/net.html#serverlisten
+        // it's not safe if we increase this number
+        backlog: 5,
         closeServerOnMaxConnections: {
           closeAbove: networkOpts.maxPeers ?? Infinity,
           listenBelow: networkOpts.maxPeers ?? Infinity,
@@ -101,6 +105,9 @@ export async function createNodeJsLibp2p(
       //maxConnections: options.maxConnections,
       // DOCS: There is no way to turn off autodial other than setting minConnections to 0
       minConnections: 0,
+      // the maximum number of pending connections libp2p will accept before it starts rejecting incoming connections.
+      // make it the same to backlog option above
+      maxIncomingPendingConnections: 5,
     },
     datastore,
     services: {