// runTimeSensitiveTest and SetRSTAvoidanceDelay to explicitly raise the delay
	// if needed.
	rstAvoidanceDelay = 1 * time.Nanosecond
}

// SetRSTAvoidanceDelay sets how long we are willing to wait between calling
// CloseWrite on a connection and fully closing the connection.
func SetRSTAvoidanceDelay(t *testing.T, d time.Duration) {
	prevDelay := rstAvoidanceDelay

		10 * time.Millisecond,
		50 * time.Millisecond,
		100 * time.Millisecond,
		500 * time.Millisecond,
		time.Second,
		5 * time.Second,
	}, func(t *testing.T, timeout time.Duration) error {
		SetRSTAvoidanceDelay(t, timeout)
		t.Logf("set RST avoidance delay to %v", timeout)

		const bodySize = 5 << 20
		req := []byte(fmt.Sprintf("POST / HTTP/1.1\r\nHost: foo.com\r\nContent-Length: %d\r\n\r\n", bodySize))

		10 * time.Millisecond,
		50 * time.Millisecond,
		100 * time.Millisecond,
		500 * time.Millisecond,
		time.Second,
		5 * time.Second,
	}, func(t *testing.T, timeout time.Duration) error {
		SetRSTAvoidanceDelay(t, timeout)
		t.Logf("set RST avoidance delay to %v", timeout)

		const deniedMsg = "sorry, denied."
		cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {