From a85e7f7442117271c97ffbedc1671a7b1ea996a5 Mon Sep 17 00:00:00 2001
From: cloudhead <cloudhead@radicle.xyz>
Date: Wed, 22 May 2024 14:46:08 +0200
Subject: [PATCH] node: Set TCP_KEEPALIVE on sockets

Ensures dead connections are not kept around longer than necessary.
Note that the ping/pong mechanism is more expensive and checks that the
session is active and healthy, while TCP_KEEPALIVE is lower level,
cheaper, and checks that the connection is still alive.
---
 Cargo.lock                        |  1 +
 radicle-node/Cargo.toml           |  1 +
 radicle-node/src/wire/protocol.rs | 11 ++++++++++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index 34d11e13..81bb55b1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2683,6 +2683,7 @@ dependencies = [
  "serde",
  "serde_json",
  "snapbox",
+ "socket2",
  "sqlite",
  "tempfile",
  "thiserror",
diff --git a/radicle-node/Cargo.toml b/radicle-node/Cargo.toml
index cda98b6d..96c76b94 100644
--- a/radicle-node/Cargo.toml
+++ b/radicle-node/Cargo.toml
@@ -39,6 +39,7 @@ scrypt = { version = "0.11.0", default-features = false }
 serde = { version = "1", features = ["derive"] }
 serde_json = { version = "1", features = ["preserve_order"] }
 snapbox = { version = "0.4.3", optional = true }
+socket2 = { version = "0.5.7" }
 tempfile = { version = "3.3.0" }
 thiserror = { version = "1" }
 
diff --git a/radicle-node/src/wire/protocol.rs b/radicle-node/src/wire/protocol.rs
index f6f8de35..0df48147 100644
--- a/radicle-node/src/wire/protocol.rs
+++ b/radicle-node/src/wire/protocol.rs
@@ -1181,8 +1181,17 @@ fn session<G: Signer + Ecdh<Pk = NodeId>>(
     connection.set_read_timeout(Some(DEFAULT_CONNECTION_TIMEOUT))?;
     connection.set_write_timeout(Some(DEFAULT_CONNECTION_TIMEOUT))?;
 
+    let sock = socket2::Socket::from(connection);
+    let ka = socket2::TcpKeepalive::new()
+        .with_time(time::Duration::from_secs(30))
+        .with_interval(time::Duration::from_secs(10))
+        .with_retries(3);
+    if let Err(e) = sock.set_tcp_keepalive(&ka) {
+        log::warn!(target: "wire", "Unable to set TCP_KEEPALIVE on fd {}: {e}", sock.as_raw_fd());
+    }
+
     let socks5 = socks5::Socks5::with(remote_addr, force_proxy);
-    let proxy = Socks5Session::with(connection, socks5);
+    let proxy = Socks5Session::with(sock.into(), socks5);
     let pair = G::generate_keypair();
     let keyset = Keyset {
         e: pair.0,