From 87e2011c05a20cf257ebf18e95880af93e7fccc0 Mon Sep 17 00:00:00 2001
From: Keenan Tims <ktims@gotroot.ca>
Date: Thu, 22 Oct 2026 17:49:12 -0700
Subject: [PATCH] Send a control packet immediately on session state change

RFC 5880 6.8.7 says a packet SHOULD be sent between periodic transmissions when its contents would change, so peers see state changes without waiting up to a full interval.
---
 src/bin/rust-bfdd.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/bin/rust-bfdd.rs b/src/bin/rust-bfdd.rs
index 28870ba..15ad371 100644
--- a/src/bin/rust-bfdd.rs
+++ b/src/bin/rust-bfdd.rs
@@ -545,6 +545,10 @@ impl BfdSession {
             _ => {}
         }
         self.state.set_session_state(new_state);
+        // https://datatracker.ietf.org/doc/html/rfc5880#section-6.8.7
+        //   A BFD Control packet SHOULD be transmitted during the interval between periodic Control packet
+        //   transmissions when the contents of that packet would differ from that in the previously transmitted packet
+        self.transmit_control_packet(false).await;
     }
 
     async fn run(&mut self) {