wgengine/magicsock: close test loggers once we're done with them

This is a big hammer approach to helping with #1132.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

types/logger/logger.go

@@ -192,3 +192,27 @@ func Filtered(logf Logf, allow func(s string) bool) Logf {
 		logf(format, args...)
 	}
 }
+
+// LogfCloser wraps logf to create a logger that can be closed.
+// Calling close makes all future calls to newLogf into no-ops.
+func LogfCloser(logf Logf) (newLogf Logf, close func()) {
+	var (
+		mu     sync.Mutex
+		closed bool
+	)
+	close = func() {
+		mu.Lock()
+		defer mu.Unlock()
+		closed = true
+	}
+	newLogf = func(msg string, args ...interface{}) {
+		mu.Lock()
+		if closed {
+			mu.Unlock()
+			return
+		}
+		mu.Unlock()
+		logf(msg, args...)
+	}
+	return newLogf, close
+}

wgengine/magicsock/magicsock_test.go

@@ -567,9 +567,12 @@ func TestConnClosing(t *testing.T) {
 		t.Fatalf("generating private key: %v", err)
 	}
 
+	logf, closeLogf := logger.LogfCloser(t.Logf)
+	defer closeLogf()
+
 	epCh := make(chan []string, 100)
 	conn, err := NewConn(Options{
-		Logf:           t.Logf,
+		Logf:           logf,
 		PacketListener: nettype.Std{},
 		EndpointsFunc: func(eps []string) {
 			epCh <- eps
@@ -580,7 +583,7 @@ func TestConnClosing(t *testing.T) {
 		t.Fatalf("constructing magicsock: %v", err)
 	}
 
-	derpMap, cleanup := runDERPAndStun(t, t.Logf, nettype.Std{}, netaddr.IPv4(127, 0, 3, 1))
+	derpMap, cleanup := runDERPAndStun(t, logf, nettype.Std{}, netaddr.IPv4(127, 0, 3, 1))
 	defer cleanup()
 
 	// The point of this test case is to exercise handling in derpWriteChanOfAddr() which
@@ -597,11 +600,11 @@ func TestConnClosing(t *testing.T) {
 	}
 
 	tun := tuntest.NewChannelTUN()
-	tsTun := tstun.WrapTUN(t.Logf, tun.TUN())
-	tsTun.SetFilter(filter.NewAllowAllForTest(t.Logf))
+	tsTun := tstun.WrapTUN(logf, tun.TUN())
+	tsTun.SetFilter(filter.NewAllowAllForTest(logf))
 
 	dev := device.NewDevice(tsTun, &device.DeviceOptions{
-		Logger:         wireguardGoLogger(t.Logf),
+		Logger:         wireguardGoLogger(logf),
 		CreateEndpoint: conn.CreateEndpoint,
 		CreateBind:     conn.CreateBind,
 		SkipBindUpdate: true,
@@ -634,12 +637,15 @@ func TestConnClosed(t *testing.T) {
 		stunIP: sif.V4(),
 	}
 
-	derpMap, cleanup := runDERPAndStun(t, t.Logf, d.stun, d.stunIP)
+	logf, closeLogf := logger.LogfCloser(t.Logf)
+	defer closeLogf()
+
+	derpMap, cleanup := runDERPAndStun(t, logf, d.stun, d.stunIP)
 	defer cleanup()
 
-	ms1 := newMagicStack(t, logger.WithPrefix(t.Logf, "conn1: "), d.m1, derpMap)
+	ms1 := newMagicStack(t, logger.WithPrefix(logf, "conn1: "), d.m1, derpMap)
 	defer ms1.Close()
-	ms2 := newMagicStack(t, logger.WithPrefix(t.Logf, "conn2: "), d.m2, derpMap)
+	ms2 := newMagicStack(t, logger.WithPrefix(logf, "conn2: "), d.m2, derpMap)
 	defer ms2.Close()
 
 	cleanup = meshStacks(t.Logf, []*magicStack{ms1, ms2})