Function makeHangDialer

wgengine/netstack/netstack_test.go:710–735

makeHangDialer returns a dialer that notifies the returned channel when a connection is dialed and then hangs until the test finishes.

(tb testing.TB)

// makeHangDialer returns a dialer that notifies the returned channel when a
// connection is dialed and then hangs until the test finishes.
func makeHangDialer(tb testing.TB) (netx.DialFunc, chan struct{}) {
	done := make(chan struct{})
	tb.Cleanup(func() {
		close(done)
	})

	gotConn := make(chan struct{}, 1)
	fn := func(ctx context.Context, network, address string) (net.Conn, error) {
		// Signal that we have a new connection
		tb.Logf("hangDialer: called with network=%q address=%q", network, address)
		select {
		case gotConn <- struct{}{}:
		default:
		}

		// Hang until the test is done.
		select {
		case <-ctx.Done():
			tb.Logf("context done")
		case <-done:
			tb.Logf("function completed")
		}
		return nil, fmt.Errorf("canceled")
	}
	return fn, gotConn
}

// TestTCPForwardLimits verifies that the limits on the TCP forwarder work in a
// success case (i.e. when we don't hit the limit).