How to determine if a string is a valid IPv4 or IPv6 address in C#?

Question

I know regex is dangerous for validating IP addresses because of the different forms an IP address can take.

I\'ve seen similar questions for C and C++, and those we

Answer 1

A combination of tests applied to a string or IPAddress, works for me..

        /// 

    /// Test string for valid ip address format
    /// 
    /// 
    /// The ip address string
    /// 
    /// Returns true if address is a valid format
    public static bool IsValidIP(IPAddress Ip)
    {
        byte[] addBytes = Ip.GetAddressBytes();

        switch (Ip.AddressFamily)
        {
            case AddressFamily.InterNetwork:
                if (addBytes.Length == 4)
                    return true;
                break;
            case AddressFamily.InterNetworkV6:
                if (addBytes.Length == 16)
                    return true;
                break;
            default:
                break;
        }

        return false;
    }

    /// 

    /// Test string for valid ip address format
    /// 
    /// 
    /// The ip address string
    /// 
    /// Returns true if address is a valid format
    public static bool IsValidIP(string Address)
    {
        IPAddress ip;
        if (IPAddress.TryParse(Address, out ip))
        {
            switch (ip.AddressFamily)
            {
                case System.Net.Sockets.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 System.Net.Sockets.AddressFamily.InterNetworkV6:
                    if (Address.Contains(":") && Address.Length > 15)
                        return true;
                    break;
                default:
                    break;
            }
        }

        return false;
    }