func findAvailable()

in internal/testutil/testutil.go [47:76]

• 23 lines of code
• 7 McCabe index (conditional complexity)

func findAvailable(t testing.TB, network string) string {
	// Retry has been added for windows as net.Listen can return a port that is not actually available. Details can be
	// found in https://github.com/docker/for-win/issues/3171 but to summarize Hyper-V will reserve ranges of ports
	// which do not show up under the "netstat -ano" but can only be found by
	// "netsh interface ipv4 show excludedportrange protocol=tcp".  We'll use []exclusions to hold those ranges and
	// retry if the port returned by GetAvailableLocalAddress falls in one of those them.
	var exclusions []portpair
	portFound := false
	if runtime.GOOS == "windows" {
		exclusions = getExclusionsList(network, t)
	}

	var endpoint string
	for !portFound {
		endpoint = findAvailableAddress(network, t)
		_, port, err := net.SplitHostPort(endpoint)
		require.NoError(t, err)
		portFound = true
		if runtime.GOOS == "windows" {
			for _, pair := range exclusions {
				if port >= pair.first && port <= pair.last {
					portFound = false
					break
				}
			}
		}
	}

	return endpoint
}