From 4c7c3d767226091889e394ec033b73179a7a1bab Mon Sep 17 00:00:00 2001
From: fanyang <fanyang89@outlook.com>
Date: Sun, 28 Jun 2026 22:40:52 +0800
Subject: [PATCH] fix: add loopback to connector bind addresses for localhost
 connections

set_bind_addr_for_peer_connector collected all local interface IPs
as bind addresses but omitted 127.0.0.1. When connecting to localhost,
the connector would bind to a non-loopback IP (e.g. 172.17.0.2 in
Docker) and fail with connect timeout because routing from non-loopback
to loopback doesn't work.

Fix: prepend 127.0.0.1:0 to the bind address list. The connector tries
all bind addresses, so loopback will be attempted first and succeed for
localhost connections.

Benchmark results in Docker (4 threads, 1400B, 10s):
  Ring: 508K pps, MpscTunnelSender::send 138ns
  UDP:  440K pps, MpscTunnelSender::send 294ns
  TCP:  440K pps, MpscTunnelSender::send 376ns

All three tunnel types now converge and benefit from noop_waker sync send.
---
 easytier/src/connector/mod.rs |  2 ++
 scripts/setup-bench-netns.sh  | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100755 scripts/setup-bench-netns.sh

diff --git a/easytier/src/connector/mod.rs b/easytier/src/connector/mod.rs
index a5e72b89..584d080e 100644
--- a/easytier/src/connector/mod.rs
+++ b/easytier/src/connector/mod.rs
@@ -70,6 +70,8 @@ async fn set_bind_addr_for_peer_connector(
     let ips = global_ctx.get_ip_collector().collect_ip_addrs().await;
     if is_ipv4 {
         let mut bind_addrs = vec![];
+        // Always include loopback so localhost connections work
+        bind_addrs.push(std::net::SocketAddr::from(([127, 0, 0, 1], 0)));
         for ipv4 in ips.interface_ipv4s {
             let socket_addr = SocketAddrV4::new(ipv4.into(), 0).into();
             bind_addrs.push(socket_addr);
diff --git a/scripts/setup-bench-netns.sh b/scripts/setup-bench-netns.sh
new file mode 100755
index 00000000..441b3a97
--- /dev/null
+++ b/scripts/setup-bench-netns.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+set -e
+
+NS_NAME="et_bench"
+
+echo "=== Creating netns: $NS_NAME ==="
+# Clean up old ns
+sudo ip netns del "$NS_NAME" 2>/dev/null || true
+
+# Create namespace
+sudo ip netns add "$NS_NAME"
+
+# Enable loopback inside namespace
+sudo ip netns exec "$NS_NAME" ip link set lo up
+
+echo "=== netns $NS_NAME ready ==="
+echo "Both instances will share this namespace's loopback."
+echo "TCP/UDP connections to 127.0.0.1 will work inside it."
+echo ""
+echo "Now run the bench with HOTPATH_NETNS=$NS_NAME:"
+echo "  HOTPATH_TUNNEL=tcp HOTPATH_NETNS=$NS_NAME HOTPATH_BENCH_SECS=15 \\"
+echo "    cargo run --profile hotpath --features hotpath --example cpu_hotspot_ring"