How do I check if IP range is in IPV4 and IPV6 CIDR format in C#?

Question

For example, How do I validate that the IP range 192.168.2.0/24 is in IPV4 or IPV6 CIDR format?

Need help modifying:

public static bool IsValidIP(string address)
{
    IPAddress ip;
    if (!IPAddress.TryParse(address, out ip)) return false;

    switch (ip.AddressFamily)
    {
        case AddressFamily.InterNetwork:
            if (address.Length > 6 && address.Contains("."))
            {
                string[] s = address.Split('.');
                if (s.Length == 4 && s[0].Length > 0 && s[1].Length > 0 && s[2].Length > 0 && s[3].Length > 0)
                    return true;
            }
            break;
        case AddressFamily.InterNetworkV6:
            if (address.Contains(":") && address.Length > 15)
                return true;
            break;
    }
    return false;
}

Answer 1

CIDR always ends with a "/xx", so just knock that off if it exists and parse the stuff before using the IPAddress class.

using System.Net;

var input = "192.168.2.0/24";
// or
var input = "2345:0425:2CA1:0000:0000:0567:5673:23b5/64";

var segments = input.Split('/');

var isValidIpAddress = IPAddress.TryParse(segments[0], out var parsedAddress);
Console.WriteLine(parsedAddress.AddressFamily);

var isCIDR = segments.Length is 2; // you should also validate segments[1] 
                                   // is an allowed value as well based on
                                   // the IP version.