From a1460b0a2861d5bb34ba25d409b234468f269e4e Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Sat, 24 Oct 2026 03:19:28 +0200
Subject: use nonce in handshake

To prevent stale hello replies to cause joins and thus stale sessions,
each run gets a random ID, which used as nonce in the handshake.
---
 src/transport/mycelium.rs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'src/transport/mycelium.rs')

diff --git a/src/transport/mycelium.rs b/src/transport/mycelium.rs
index 4c03839..51bbfab 100644
--- a/src/transport/mycelium.rs
+++ b/src/transport/mycelium.rs
@@ -877,6 +877,7 @@ pub struct HelloRequestShadow {
     epoch: EpochShadow,
     auth: ByteBuf,
     ready: bool,
+    run_id: ByteBuf,
 }
 
 #[derive(Serialize, Deserialize)]
@@ -890,6 +891,7 @@ pub struct HelloReplyShadow<'a> {
     #[serde(default)]
     auth: ByteBuf,
     ready: bool,
+    run_id: ByteBuf,
 }
 
 #[derive(Serialize, Deserialize)]
@@ -940,6 +942,7 @@ pub fn hello_request_to_bytes(msg: &HelloRequest) -> Result<Vec<u8>, rmp_serde::
         epoch: epoch_to_shadow(&msg.epoch),
         auth: ByteBuf::from(msg.auth.clone()),
         ready: msg.ready,
+        run_id: ByteBuf::from(msg.run_id.to_vec()),
     })
 }
 pub fn bytes_to_hello_request(bytes: &[u8]) -> Result<HelloRequest, TransportError> {
@@ -949,9 +952,17 @@ pub fn bytes_to_hello_request(bytes: &[u8]) -> Result<HelloRequest, TransportErr
         epoch: epoch_from_shadow(shadow.epoch)?,
         auth: shadow.auth.into_vec(),
         ready: shadow.ready,
+        run_id: run_id_from_shadow(&shadow.run_id)?,
     })
 }
 
+fn run_id_from_shadow(bytes: &ByteBuf) -> Result<crate::transport::RunId, TransportError> {
+    bytes
+        .as_slice()
+        .try_into()
+        .map_err(|_| TransportError::InvalidPayload("run id must be 16 bytes".into()))
+}
+
 // --- HelloReply ---
 pub fn hello_reply_to_bytes(msg: &HelloReply) -> Result<Vec<u8>, rmp_serde::encode::Error> {
     let shadow = HelloReplyShadow {
@@ -960,6 +971,7 @@ pub fn hello_reply_to_bytes(msg: &HelloReply) -> Result<Vec<u8>, rmp_serde::enco
         epoch: epoch_to_shadow(&msg.epoch),
         auth: ByteBuf::from(msg.auth.clone()),
         ready: msg.ready,
+        run_id: ByteBuf::from(msg.run_id.to_vec()),
     };
     rmp_serde::to_vec(&shadow)
 }
@@ -971,6 +983,7 @@ pub fn bytes_to_hello_reply(bytes: &[u8]) -> Result<HelloReply, TransportError>
         epoch: epoch_from_shadow(shadow.epoch)?,
         auth: shadow.auth.into_vec(),
         ready: shadow.ready,
+        run_id: run_id_from_shadow(&shadow.run_id)?,
     })
 }
 
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