From 0b13e180c4dcd38e3ea8ffeecc9e5ebefa023212 Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Mon, 26 Oct 2026 05:54:53 +0100
Subject: number handshakes

This prevents late hellos from resetting the session.
---
 src/transport/mod.rs  | 4 ++++
 src/transport/wire.rs | 2 ++
 2 files changed, 6 insertions(+)

(limited to 'src/transport')

diff --git a/src/transport/mod.rs b/src/transport/mod.rs
index b2ce63f..614ac48 100644
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -256,6 +256,10 @@ pub struct HelloRequest {
     /// Random per run of the sender; the reply echoes it.
     #[serde(with = "crate::transport::wire::codec::run_id")]
     pub run_id: RunId,
+    /// The handshake's number: the sender numbers the handshakes it starts in a run,
+    /// with all peers, from 1. A retry carries the same number, so the recipient resets
+    /// its sync session only for a new handshake, not for every resend or late copy.
+    pub handshake: u32,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
diff --git a/src/transport/wire.rs b/src/transport/wire.rs
index 8a8cbb8..e055393 100644
--- a/src/transport/wire.rs
+++ b/src/transport/wire.rs
@@ -271,6 +271,7 @@ mod tests {
             auth: vec![1, 2, 3],
             ready: true,
             run_id: [4; 16],
+            handshake: 7,
         });
         let ParsedMessage::Hello(decoded) = decode(&encode(&hello).unwrap()).unwrap() else {
             panic!("not a HELLO");
@@ -279,6 +280,7 @@ mod tests {
         assert_eq!((decoded.epoch, decoded.epoch_seq), (epoch, 1));
         assert_eq!(decoded.auth, vec![1, 2, 3]);
         assert_eq!(decoded.run_id, [4; 16]);
+        assert_eq!(decoded.handshake, 7);
 
         let reply = ParsedMessage::HelloReply(HelloReply {
             swarm_id: "swarm".into(),
-- 
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