From c1bd50bce5043204f522e46ee87f4e8806ccfb98 Mon Sep 17 00:00:00 2001
From: Maksim C <jstars.tech@gmail.com>
Date: Fri, 29 May 2026 11:29:58 +0300
Subject: [PATCH] fix(core): stabilize direct endpoint probing

Register probe tokens before sending packets so fast LAN pong replies cannot
arrive before tracking exists. Recompute routes when inbound probes revive or
create direct endpoints, keeping direct peer routes selected after recovery.
---
 core/nylon_endpoints.go | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/core/nylon_endpoints.go b/core/nylon_endpoints.go
index 67812ab1..22b435a5 100644
--- a/core/nylon_endpoints.go
+++ b/core/nylon_endpoints.go
@@ -33,6 +33,10 @@ func (n *Nylon) Probe(node state.NodeId, ep *state.NylonEndpoint, waitErr bool)
 		return err
 	}
 
+	n.PingBuf.Set(token, EpPing{
+		TimeSent: time.Now(),
+	}, ttlcache.DefaultTTL)
+
 	wg := sync.WaitGroup{}
 	wg.Add(1)
 
@@ -41,12 +45,8 @@ func (n *Nylon) Probe(node state.NodeId, ep *state.NylonEndpoint, waitErr bool)
 		defer wg.Done()
 		sendErr = n.SendNylon(ping, nep, peer)
 		if sendErr != nil {
-			return
+			n.PingBuf.Delete(token)
 		}
-
-		n.PingBuf.Set(token, EpPing{
-			TimeSent: time.Now(),
-		}, ttlcache.DefaultTTL)
 	}()
 
 	if waitErr {
@@ -60,11 +60,14 @@ func handleProbe(n *Nylon, pkt *protocol.Ny_Probe, endpoint conn.Endpoint, peer
 	if pkt.ResponseToken == nil {
 		// ping
 		// build pong response
-		res := pkt
-		res.ResponseToken = new(rand.Uint64())
+		responseToken := pkt.Token
+		res := &protocol.Ny_Probe{
+			Token:         pkt.Token,
+			ResponseToken: &responseToken,
+		}
 
 		// send pong
-		err := n.SendNylon(&protocol.Ny{Type: &protocol.Ny_ProbeOp{ProbeOp: pkt}}, endpoint, peer)
+		err := n.SendNylon(&protocol.Ny{Type: &protocol.Ny_ProbeOp{ProbeOp: res}}, endpoint, peer)
 		if err != nil {
 			n.Log.Error("Failed to send nylon packet to node", "node", node, "error", err)
 			return
@@ -98,10 +101,12 @@ func handleProbePing(n *Nylon, node state.NodeId, wgEndpoint conn.Endpoint) {
 				// refresh wireguard ep
 				dep.WgEndpoint = wgEndpoint
 
-				if !dep.IsActive() {
+				wasInactive := !dep.IsActive()
+				dep.Renew()
+				if wasInactive {
+					ComputeRoutes(n.RouterState, n)
 					n.UpdateNeighbour(node)
 				}
-				dep.Renew()
 
 				if n.DBG_log_probe {
 					n.Log.Debug("probe from", "addr", ap.String())
@@ -117,6 +122,7 @@ func handleProbePing(n *Nylon, node state.NodeId, wgEndpoint conn.Endpoint) {
 			newEp.Renew()
 			neigh.Eps = append(neigh.Eps, newEp)
 			// push route update to improve convergence time
+			ComputeRoutes(n.RouterState, n)
 			n.UpdateNeighbour(node)
 			return
 		}