The place is the bug on this code? – Getting Assist

THis strategies checks if the primary IP community comprises the second (the maskSize of first ought to be <= that the maskSize of second, and their IPs ought to be similar all through the primary masks:

func ContainsIPNetwork(first, second web.IPNet) bool {
	if len(first.IP) != len(second.IP) {
		return false
	}

	i := len(first.IP) - 1

	for i > 0 && (first.Masks[i]|second.Masks[i] == 0) {
		i--
	}

	if first.Masks[i] > second.Masks[i] || ((first.IP[i]^second.IP[i])&first.Masks[i] != 0) {
		return false
	}

	i--

	for i >= 0 && first.IP[i] == second.IP[i] {
		i--
	}

	return i == -1
}

There’s a bug within the code above, it really works for many instances, however not all. Can you work it out ?

I for one can not, however there’s actually a bug. What ought to I do to determine it out ?

I didn’t checked the code however:

• how have you learnt there;s a bug? (assessments, procedures, …)
• have you ever tried to debug the code?

listed here are 2 check instances that fail:

first {IP:0.0.0.0 Masks:00000000}, second {IP:2.0.0.0 Masks:ffffffff}, comprises false <–unsuitable
first {IP:0.0.0.0 Masks:00000000}, second {IP:255.255.255.255 Masks:ffffffff}, comprises false <–unsuitable

To your first instance, on this loop:

when i == 0, first.IP[0] == 0 and second.IP[0] == 2, so the loop breaks and returns i == -1 (0 == -1, false).

To your second instance, in the identical loop, when i is decremented from 3 to 2, first.IP[2] == 0 and second.IP[2] == 255, so the loop breaks and returns i == -1 (2 == -1, false).

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