add optional IP anonymization

[aine-etke]

This PR provides an option to anonymize IP:

• in context via Context.AnonymizedIP()
• in (old) logger middleware via remote_ip_anon token
• in (new) request logger middleware via AnonymizeRemoteIP option

[aldas]

Hi,

I we can not accept this as adding new method to Context interface would be API breaking change as that type is an Interface.

I think you would be totally fine if you add utility public function in your code base like that. There is no need to add it to the Context interface.

func AnonymizedIP(c echo.Context) string {
	ip := c.RealIP()

	if ip == "" {
		return "" // safeguard
	}
	parsedIP := net.ParseIP(ip)
	if parsedIP == nil {
		return ip // safeguard, not an ip
	}

	// IPv4
	if parsedIP.To4() != nil {
		ipParts := strings.Split(parsedIP.String(), ".")
		if len(ipParts) == 4 {
			ipParts[3] = "0"
			return strings.Join(ipParts, ".")
		}
	}

	// IPv6
	ipParts := strings.Split(parsedIP.String(), ":")
	ipParts[len(ipParts)-1] = "0"
	return strings.Join(ipParts, ":")
}

[aine-etke]

Hello, I already did a public utility function in https://github.com/etkecc/go-kit/blob/main/ip.go but just wanted to provide a "frictionless" version as part of the echo.

Would you mind telling if you are against Context.AnonymizedIP() method specifically and will accept middleware changes (logger and request logger), or you don't like the proposed idea at all, please?