From 881a652713a6231ad31596b80b674986d0170868 Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@meshlink.io>
Date: Fri, 28 Aug 2020 23:01:50 +0200
Subject: [PATCH 1/1] Start sending UDP probes after a channel retransmit
 event.

Before we started doing PMTU probes after a retransmit event, but with
the new UDP probing we need to restart the UDP probes instead, as they
will be able to detect failing UDP communication much faster.
---
 src/graph.c    | 2 ++
 src/meshlink.c | 9 +++++----
 src/pmtu.c     | 5 ++++-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/graph.c b/src/graph.c
index f68cf008..0179059d 100644
--- a/src/graph.c
+++ b/src/graph.c
@@ -161,6 +161,7 @@ static void check_reachability(meshlink_handle_t *mesh) {
 			n->status.udp_confirmed = false;
 			n->maxmtu = MTU;
 			n->minmtu = 0;
+			n->udpprobes = 0;
 			n->mtuprobes = 0;
 		}
 
@@ -189,6 +190,7 @@ static void check_reachability(meshlink_handle_t *mesh) {
 			n->status.udp_confirmed = false;
 			n->maxmtu = MTU;
 			n->minmtu = 0;
+			n->udpprobes = 0;
 			n->mtuprobes = 0;
 
 			timeout_del(&mesh->loop, &n->udp_ping_timeout);
diff --git a/src/meshlink.c b/src/meshlink.c
index f92f0098..95880e31 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -30,6 +30,7 @@
 #include "node.h"
 #include "submesh.h"
 #include "packmsg.h"
+#include "pmtu.h"
 #include "prf.h"
 #include "protocol.h"
 #include "route.h"
@@ -3631,6 +3632,7 @@ static bool blacklist(meshlink_handle_t *mesh, node_t *n) {
 	n->mtu = 0;
 	n->minmtu = 0;
 	n->maxmtu = MTU;
+	n->udpprobes = 0;
 	n->mtuprobes = 0;
 	n->status.udp_confirmed = false;
 
@@ -4037,10 +4039,9 @@ static void channel_retransmit(struct utcp_connection *utcp_connection) {
 	node_t *n = utcp_connection->utcp->priv;
 	meshlink_handle_t *mesh = n->mesh;
 
-	if(n->mtuprobes == -1 && n->udp_ping_timeout.cb) {
-		timeout_set(&mesh->loop, &n->udp_ping_timeout, &(struct timespec) {
-			0, 0
-		});
+	if(!n->udpprobes) {
+		timespec_clear(&n->last_udp_probe_sent);
+		keepalive(mesh, n, false);
 	}
 }
 
diff --git a/src/pmtu.c b/src/pmtu.c
index 5220a737..36152cff 100644
--- a/src/pmtu.c
+++ b/src/pmtu.c
@@ -236,7 +236,10 @@ static void try_udp(meshlink_handle_t *mesh, node_t *n) {
 	if(elapsed.tv_sec >= interval) {
 		n->last_udp_probe_sent = mesh->loop.now;
 		send_udp_probe_packet(mesh, n, MIN_PROBE_SIZE);
-		n->udpprobes--;
+
+		if(n->status.udp_confirmed) {
+			n->udpprobes--;
+		}
 
 		if(!n->status.udp_confirmed && n->prevedge) {
 			n->status.broadcast = true;
-- 
2.39.2