/// <summary>
/// A null or empty string passed as the ipAddress will return true. An invalid ipAddress will be returned as true.
/// </summary>
/// <param name="ipAddress"></param>
/// <returns></returns>
public static bool IsNonRoutableIpAddress(string ipAddress)
{
//Reference: http://en.wikipedia.org/wiki/Reserved_IP_addresses
//if the ip address string is empty or null string, we consider it to be non-routable
if (string.IsNullOrEmpty(ipAddress))
{
return(true);
}
if (!IPAddress.TryParse(ipAddress, out var tempIpAddress))
{
return(true);
}
var ipAddressBytes = tempIpAddress.GetAddressBytes();
if (IPFormatter.IsIPv4Address(tempIpAddress))
{
if (IsIpAddressInRange(ipAddressBytes, @"10.0.0.0/8")) //Class A Private network check
{
return(true);
}
if (IsIpAddressInRange(ipAddressBytes, @"172.16.0.0/12")) //Class B private network check
{
return(true);
}
if (IsIpAddressInRange(ipAddressBytes, @"192.168.0.0/16")) //Class C private network check
{
return(true);
}
if (IsIpAddressInRange(ipAddressBytes, @"127.0.0.0/8")) //Loopback
{
return(true);
}
if (IsIpAddressInRange(ipAddressBytes, @"0.0.0.0/8")) //reserved for broadcast messages
{
return(true);
}
return(false);
}
//if ipAddress is IPv6
if (IPFormatter.IsIPv6Address(tempIpAddress))
{
if (IsIpAddressInRange(ipAddressBytes, @"::/128")) //Unspecified address
{
return(true);
}
if (IsIpAddressInRange(ipAddressBytes, @"::1/128")) //Loopback address for localhost
{
return(true);
}
if (IsIpAddressInRange(ipAddressBytes, @"2001:db8::/32")) //Addresses used in documentation
{
return(true);
}
throw new NotImplementedException();
//return false;
}
return(true);
}
private static bool IsIpAddressInRange(byte[] ipAddressBytes, string reservedIpAddress)
{
if (string.IsNullOrEmpty(reservedIpAddress))
{
return(false);
}
if (ipAddressBytes == null)
{
return(false);
}
//Split the reserved ip address into a bitmask and ip address
var ipAddressSplit = reservedIpAddress.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
if (ipAddressSplit.Length != 2)
{
return(false);
}
var ipAddressRange = ipAddressSplit[0];
if (!IPAddress.TryParse(ipAddressRange, out var ipAddress))
{
return(false);
}
// Convert the IP address to bytes.
var ipBytes = ipAddress.GetAddressBytes();
//parse the bits
if (!int.TryParse(ipAddressSplit[1], out var bits))
{
bits = 0;
}
// BitConverter gives bytes in opposite order to GetAddressBytes().
byte[] maskBytes = null;
if (IPFormatter.IsIPv4Address(ipAddress))
{
var mask = ~(uint.MaxValue >> bits);
maskBytes = BitConverter.GetBytes(mask).Reverse().ToArray();
}
else if (IPFormatter.IsIPv6Address(ipAddress))
{
//128 places
var bitArray = new BitArray(128, false);
//shift <bits> times to the right
ShiftRight(bitArray, bits, true);
//turn into byte array
maskBytes = ConvertToByteArray(bitArray).Reverse().ToArray();
}
var result = true;
//Calculate
for (var i = 0; i < ipBytes.Length; ++i)
{
result &= (byte)(ipAddressBytes[i] & maskBytes[i]) == ipBytes[i];
}
return(result);
}