From 83b2f9efbbcedea3297fea6754ea4a0e7ac6b3e0 Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Sun, 1 Nov 2026 20:59:18 +0100
Subject: libp2p: idle timeout follows keepalive

---
 src/simtest/identity.rs           |  1 +
 src/transport/libp2p/behaviour.rs |  6 +++++-
 src/transport/libp2p/config.rs    |  4 ++++
 src/transport/libp2p/mod.rs       | 10 +++++++++-
 src/transport/libp2p/tests.rs     |  3 +++
 5 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/simtest/identity.rs b/src/simtest/identity.rs
index f7ef521..7dbb722 100644
--- a/src/simtest/identity.rs
+++ b/src/simtest/identity.rs
@@ -228,6 +228,7 @@ async fn nodes_over_libp2p() {
                 internet_hosts: Vec::new(),
                 public: false,
                 memory: true,
+                keepalive: super::KEEPALIVE,
             })
             .unwrap();
             config.transport = Arc::new(transport);
diff --git a/src/transport/libp2p/behaviour.rs b/src/transport/libp2p/behaviour.rs
index 18d8011..0b9be6b 100644
--- a/src/transport/libp2p/behaviour.rs
+++ b/src/transport/libp2p/behaviour.rs
@@ -188,6 +188,8 @@ pub(super) struct Features {
     pub(super) mdns: bool,
     pub(super) upnp: bool,
     pub(super) public: bool,
+    /// How long a connection may idle (`idle_timeout`).
+    pub(super) idle_timeout: Duration,
 }
 
 impl Features {
@@ -197,6 +199,7 @@ impl Features {
             mdns: config.mdns,
             upnp: config.upnp,
             public: config.public,
+            idle_timeout: idle_timeout(config.keepalive),
         }
     }
 }
@@ -228,6 +231,7 @@ impl Behaviour {
             mdns,
             upnp,
             public,
+            idle_timeout: _,
         } = features;
         let peer_id = key.public().to_peer_id();
         let kad = public.then(|| {
@@ -335,7 +339,7 @@ pub(super) fn swarm_config(
     features: Features,
 ) -> ::libp2p::swarm::Config {
     let config = config
-        .with_idle_connection_timeout(IDLE_TIMEOUT)
+        .with_idle_connection_timeout(features.idle_timeout)
         .with_dial_concurrency_factor(DIAL_CONCURRENCY);
     if features.public {
         config
diff --git a/src/transport/libp2p/config.rs b/src/transport/libp2p/config.rs
index 348a170..712f2e2 100644
--- a/src/transport/libp2p/config.rs
+++ b/src/transport/libp2p/config.rs
@@ -32,6 +32,9 @@ pub(crate) struct Libp2pConfig {
     pub(crate) public: bool,
     /// libp2p's in-memory transport instead of TCP and QUIC: for tests.
     pub(crate) memory: bool,
+    /// The node's keepalive interval (`--keepalive`): connections idle for a few of
+    /// them are closed (`idle_timeout`).
+    pub(crate) keepalive: Duration,
 }
 
 /// The multiaddrs of option `option`.
@@ -138,6 +141,7 @@ impl Libp2pConfig {
             internet_hosts: settings.libp2p_internet_hosts.clone(),
             public: settings.libp2p_public,
             memory: false,
+            keepalive: settings.keepalive,
         })
     }
 
diff --git a/src/transport/libp2p/mod.rs b/src/transport/libp2p/mod.rs
index a159280..3ebe7f6 100644
--- a/src/transport/libp2p/mod.rs
+++ b/src/transport/libp2p/mod.rs
@@ -128,8 +128,16 @@ const SLOW_SEND: Duration = Duration::from_millis(5);
 const MAX_MESSAGE: usize = 128 << 20;
 /// How long a connection may take to come up.
 const CONNECT_TIMEOUT: Duration = Duration::from_secs(10);
-/// A connection nobody uses is closed after this; neighbours keep theirs busy.
+/// A connection nobody uses is closed after this at least; neighbours keep theirs busy,
+/// with a keepalive within one and a half intervals (`PeerState::take_keepalive_due`),
+/// so a long interval lengthens it (`idle_timeout`).
 const IDLE_TIMEOUT: Duration = Duration::from_secs(300);
+
+/// How long a connection may idle before it is closed: `IDLE_TIMEOUT`, or three
+/// keepalive intervals if that is longer.
+fn idle_timeout(keepalive: Duration) -> Duration {
+    IDLE_TIMEOUT.max(keepalive * 3)
+}
 /// Addresses of one dial tried at once (libp2p's default: 8). Hole punching (`HolePunching`)
 /// dials every address both sides offer, where they listen (LAN, VPNs, public IPv6) and
 /// where others saw them, often more than 8, while the other side punches towards all of
diff --git a/src/transport/libp2p/tests.rs b/src/transport/libp2p/tests.rs
index e105761..0f52e23 100644
--- a/src/transport/libp2p/tests.rs
+++ b/src/transport/libp2p/tests.rs
@@ -36,6 +36,7 @@ fn memory_node_with(
         internet_hosts: Vec::new(),
         public: false,
         memory: true,
+        keepalive: Duration::from_secs(60),
     })
     .unwrap();
     let address = if listen {
@@ -185,6 +186,7 @@ async fn announced_addresses_are_published_instead() {
         internet_hosts: Vec::new(),
         public: false,
         memory: true,
+        keepalive: Duration::from_secs(60),
     })
     .unwrap();
     assert_eq!(
@@ -426,6 +428,7 @@ async fn a_relay_that_is_no_node() {
         internet_hosts: Vec::new(),
         public: false,
         memory: true,
+        keepalive: Duration::from_secs(60),
     })
     .unwrap();
     let r_address = r_listen.with_p2p(r_peer).unwrap();
-- 
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