🐛 [Bug]: utils.IsIPv4 and net.ParseIP have inconsistent results

[itswcg]

Bug Description

if config EnableIPValidation set true, The correct IP is filtered.

cause:
utils.IsIPv4 and net.ParseIP have inconsistent results

utils.IsIPv4("123.117.56.255") // return fasle

ip := net.ParseIP("123.117.56.255")
ip.To4() != nil // return true

How to Reproduce

IP address ending with .255, utils.IsIPv4 always returns false.

Expected Behavior

utils.IsIPv4("123.117.56.255") return true

Fiber Version

v2.49.2

Code Snippet (optional)

app := fiber.New(fiber.Config{
	EnableIPValidation: true,
})

ips = ctx.IPs()

Checklist:

• I agree to follow Fiber's Code of Conduct.
• I have checked for existing issues that describe my problem prior to opening this one.
• I understand that improperly formatted bug reports may be closed without explanation.

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[ReneWerner87]

fiber/utils/ips.go

Lines 9 to 39 in 2374cad

	func IsIPv4(s string) bool {
	for i := 0; i < net.IPv4len; i++ {
	if len(s) == 0 {
	return false
	}
	if i > 0 {
	if s[0] != '.' {
	return false
	}
	s = s[1:]
	}
	n, ci := 0, 0
	for ci = 0; ci < len(s) && '0' <= s[ci] && s[ci] <= '9'; ci++ {
	n = n*10 + int(s[ci]-'0')
	if n >= 0xFF {
	return false
	}
	}
	if ci == 0 || (ci > 1 && s[0] == '0') {
	return false
	}
	s = s[ci:]
	}
	return len(s) == 0
	}

func IsIPv4(s string) bool {
    for i := 0; i < net.IPv4len; i++ {
        if len(s) == 0 {
            return false
        }

        if i > 0 {
            if s[0] != '.' {
                return false
            }
            s = s[1:]
        }

        n, ci := 0, 0

        for ci = 0; ci < len(s) && '0' <= s[ci] && s[ci] <= '9'; ci++ {
            n = n*10 + int(s[ci]-'0')
            if n > 0xFF { // change
                return false
            }
        }

        if ci == 0 || (ci > 1 && s[0] == '0') {
            return false
        }

        s = s[ci:]
    }

    return len(s) == 0
}

could you test this ?

[ReneWerner87]

0xFF is 255

[itswcg]

fiber/utils/ips.go

Lines 9 to 39 in 2374cad

	func IsIPv4(s string) bool {
	for i := 0; i < net.IPv4len; i++ {
	if len(s) == 0 {
	return false
	}
	if i > 0 {
	if s[0] != '.' {
	return false
	}
	s = s[1:]
	}
	n, ci := 0, 0
	for ci = 0; ci < len(s) && '0' <= s[ci] && s[ci] <= '9'; ci++ {
	n = n*10 + int(s[ci]-'0')
	if n >= 0xFF {
	return false
	}
	}
	if ci == 0 || (ci > 1 && s[0] == '0') {
	return false
	}
	s = s[ci:]
	}
	return len(s) == 0
	}

func IsIPv4(s string) bool {
    for i := 0; i < net.IPv4len; i++ {
        if len(s) == 0 {
            return false
        }

        if i > 0 {
            if s[0] != '.' {
                return false
            }
            s = s[1:]
        }

        n, ci := 0, 0

        for ci = 0; ci < len(s) && '0' <= s[ci] && s[ci] <= '9'; ci++ {
            n = n*10 + int(s[ci]-'0')
            if n > 0xFF { // change
                return false
            }
        }

        if ci == 0 || (ci > 1 && s[0] == '0') {
            return false
        }

        s = s[ci:]
    }

    return len(s) == 0
}

could you test this ?

it was passed.

utils.IsIPv4("123.117.56.255") // return true

[ReneWerner87]

ok, can you create a pull request that contains the fix and other unittest cases or should I do that?
https://github.com/gofiber/fiber/blob/master/utils/ips_test.go#L15-L32