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chore: nodes accept peer with same or higher protocol version #1778

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Merged
kevindeforth merged 3 commits into from
Jan 16, 2026
Merged

chore: nodes accept peer with same or higher protocol version #1778

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f367e8e
nodes accept peer with same or higher protocol version
kevindeforth Jan 16, 2026
1aaac25
clippy
kevindeforth Jan 16, 2026
33fac66
improve test code
kevindeforth Jan 16, 2026
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22 changes: 17 additions & 5 deletions crates/node/src/network/handshake.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ pub async fn p2p_handshake<T: AsyncRead + AsyncWrite + Unpin>(
}

let other_protocol_version = u32::from_be_bytes(other_handshake[1..].try_into().unwrap());
if other_protocol_version != MPC_PROTOCOL_VERSION {
if other_protocol_version < MPC_PROTOCOL_VERSION {

@netrome netrome Jan 16, 2026

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For future reference, we plan to keep track of the agreed protocol version in a future release so newer nodes will know which version of the protocol they need to "speak". However, in this case the old nodes are simply "trusting" newer nodes to decide if they want to accept the connection and not, and the responsibility is on the newer nodes to communicate in a backwards compatible way.

anyhow::bail!(
"Incompatible protocol version; we have {}, they have {}",
MPC_PROTOCOL_VERSION,
Expand Down Expand Up @@ -61,20 +61,32 @@ mod tests {
}

#[tokio::test]
async fn test_p2p_handshake_different_version() {
async fn test_p2p_handshake_accept_higher_version() {
let (a, mut b) = tokio::io::duplex(1024);
let new_version = MPC_PROTOCOL_VERSION + 1;
let a_result = do_handshake(a);
let mut buf = [0u8; 5];
b.read_exact(&mut buf).await.unwrap();
buf[1..].copy_from_slice(&(MPC_PROTOCOL_VERSION + 1).to_be_bytes());
buf[1..].copy_from_slice(&(new_version).to_be_bytes());
b.write_all(&buf).await.unwrap();
a_result.await.unwrap();
}

#[tokio::test]
async fn test_p2p_handshake_reject_lower_version() {
let (a, mut b) = tokio::io::duplex(1024);
let a_result = do_handshake(a);
let mut buf = [0u8; 5];
let old_version = MPC_PROTOCOL_VERSION - 1;
b.read_exact(&mut buf).await.unwrap();
buf[1..].copy_from_slice(&(old_version).to_be_bytes());
b.write_all(&buf).await.unwrap();
let err = a_result.await.unwrap_err();
assert_eq!(
err.to_string(),
format!(
"Incompatible protocol version; we have {}, they have {}",
MPC_PROTOCOL_VERSION,
MPC_PROTOCOL_VERSION + 1
MPC_PROTOCOL_VERSION, old_version
)
);
}
Expand Down