From 99d39e743be4b3693ca0b91b0e5f18556e4ef2b0 Mon Sep 17 00:00:00 2001
From: Milos Gajdos <milosgajdos83@gmail.com>
Date: Thu, 22 Aug 2019 16:31:37 +0100
Subject: [PATCH] Lock when setting loopback flag and receiving keepalives

---
 tunnel/default.go     | 6 ++++++
 tunnel/tunnel_test.go | 9 ++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tunnel/default.go b/tunnel/default.go
index e4328837..69a5d878 100644
--- a/tunnel/default.go
+++ b/tunnel/default.go
@@ -73,6 +73,8 @@ func newTunnel(opts ...Option) *tun {
 
 // Init initializes tunnel options
 func (t *tun) Init(opts ...Option) error {
+	t.Lock()
+	defer t.Unlock()
 	for _, o := range opts {
 		o(&t.options)
 	}
@@ -230,7 +232,9 @@ func (t *tun) listen(link *link) {
 
 			// are we connecting to ourselves?
 			if token == t.token {
+				t.Lock()
 				link.loopback = true
+				t.Unlock()
 			}
 
 			// nothing more to do
@@ -242,7 +246,9 @@ func (t *tun) listen(link *link) {
 			continue
 		case "keepalive":
 			log.Debugf("Tunnel link %s received keepalive", link.Remote())
+			t.Lock()
 			link.lastKeepAlive = time.Now()
+			t.Unlock()
 			continue
 		case "message":
 			// process message
diff --git a/tunnel/tunnel_test.go b/tunnel/tunnel_test.go
index 5b6cfbc0..3fc84b6d 100644
--- a/tunnel/tunnel_test.go
+++ b/tunnel/tunnel_test.go
@@ -10,6 +10,8 @@ import (
 
 // testAccept will accept connections on the transport, create a new link and tunnel on top
 func testAccept(t *testing.T, tun Tunnel, wait chan bool, wg *sync.WaitGroup) {
+	defer wg.Done()
+
 	// listen on some virtual address
 	tl, err := tun.Listen("test-tunnel")
 	if err != nil {
@@ -43,7 +45,8 @@ func testAccept(t *testing.T, tun Tunnel, wait chan bool, wg *sync.WaitGroup) {
 			t.Fatal(err)
 		}
 
-		wg.Done()
+		wait <- true
+
 		return
 	}
 }
@@ -79,6 +82,8 @@ func testSend(t *testing.T, tun Tunnel, wait chan bool, wg *sync.WaitGroup) {
 		t.Fatal(err)
 	}
 
+	<-wait
+
 	if v := mr.Header["test"]; v != "accept" {
 		t.Fatalf("Message not received from accepted side. Received: %s", v)
 	}
@@ -140,6 +145,8 @@ func TestLoopbackTunnel(t *testing.T) {
 	}
 	defer tun.Close()
 
+	time.Sleep(500 * time.Millisecond)
+
 	wait := make(chan bool)
 
 	var wg sync.WaitGroup