From eb7a0db18ea71a44999d6a37b4b179dac0ed9bc7 Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@tinc-vpn.org>
Date: Sun, 11 Jan 2015 13:31:01 +0100
Subject: [PATCH] Always keep UDP mappings alive for nodes that also have a
 meta-connection.

This is necessary for assisting with UDP hole punching. But we don't
need to know the PMTU for this, so only send UDP probes.
---
 src/net.c        |  2 ++
 src/net.h        |  1 +
 src/net_packet.c | 23 ++++++++++++++++-------
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/net.c b/src/net.c
index 91b93056..5f3f6e78 100644
--- a/src/net.c
+++ b/src/net.c
@@ -154,6 +154,7 @@ static void timeout_handler(void *data) {
 
 		if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 			if(c->edge) {
+				try_tx(c->node, false);
 				if(c->status.pinged) {
 					logger(DEBUG_CONNECTIONS, LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds", c->name, c->hostname, (long)now.tv_sec - c->last_ping_time);
 				} else if(c->last_ping_time + pinginterval <= now.tv_sec) {
@@ -170,6 +171,7 @@ static void timeout_handler(void *data) {
 			}
 			terminate_connection(c, c->edge);
 		}
+
 	}
 
 	timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
diff --git a/src/net.h b/src/net.h
index 660ffc49..cfc44d23 100644
--- a/src/net.h
+++ b/src/net.h
@@ -214,6 +214,7 @@ extern void retry(void);
 extern int reload_configuration(void);
 extern void load_all_subnets(void);
 extern void load_all_nodes(void);
+extern void try_tx(struct node_t *n, bool);
 
 #ifndef HAVE_MINGW
 #define closesocket(s) close(s)
diff --git a/src/net_packet.c b/src/net_packet.c
index 0021aabb..99063ac2 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -1087,7 +1087,7 @@ static void try_mtu(node_t *n) {
    idle.
 */
 
-static void try_tx_sptps(node_t *n) {
+static void try_tx_sptps(node_t *n, bool mtu) {
 	/* If n is a TCP-only neighbor, we'll only use "cleartext" PACKET
 	   messages anyway, so there's no need for SPTPS at all. */
 
@@ -1110,13 +1110,14 @@ static void try_tx_sptps(node_t *n) {
 	/* If we do have a relay, try everything with that one instead. */
 
 	if(via != n)
-		return try_tx_sptps(via);
+		return try_tx_sptps(via, mtu);
 
 	try_udp(n);
-	try_mtu(n);
+	if(mtu)
+		try_mtu(n);
 }
 
-static void try_tx_legacy(node_t *n) {
+static void try_tx_legacy(node_t *n, bool mtu) {
 	/* Does he have our key? If not, send one. */
 
 	if(!n->status.validkey_in)
@@ -1133,7 +1134,15 @@ static void try_tx_legacy(node_t *n) {
 	}
 
 	try_udp(n);
-	try_mtu(n);
+	if(mtu)
+		try_mtu(n);
+}
+
+void try_tx(node_t *n, bool mtu) {
+	if(n->status.sptps)
+		try_tx_sptps(n, mtu);
+	else
+		try_tx_legacy(n, mtu);
 }
 
 void send_packet(node_t *n, vpn_packet_t *packet) {
@@ -1166,7 +1175,7 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 
 	if(n->status.sptps) {
 		send_sptps_packet(n, packet);
-		try_tx_sptps(n);
+		try_tx_sptps(n, true);
 		return;
 	}
 
@@ -1186,7 +1195,7 @@ void send_packet(node_t *n, vpn_packet_t *packet) {
 	}
 
 	send_udppacket(via, packet);
-	try_tx_legacy(via);
+	try_tx_legacy(via, true);
 }
 
 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
-- 
2.20.1