retransmit the CONNECTION_CLOSE packet when late packets arrive

internal/utils/atomic_bool.go

@@ -0,0 +1,22 @@
+package utils
+
+import "sync/atomic"
+
+// An AtomicBool is an atomic bool
+type AtomicBool struct {
+	v int32
+}
+
+// Set sets the value
+func (a *AtomicBool) Set(value bool) {
+	var n int32
+	if value {
+		n = 1
+	}
+	atomic.StoreInt32(&a.v, n)
+}
+
+// Get gets the value
+func (a *AtomicBool) Get() bool {
+	return atomic.LoadInt32(&a.v) != 0
+}