IpCidr.cs

using System;
using System.Net;
 
namespace Waher.Things.Ip
{
    public class IpCidr
    {
        private readonly IPAddress address;
        private readonly byte[] binary;
        private readonly int range;
 
        public IpCidr(IPAddress Address, int Range)
            : this(Address, Address.GetAddressBytes(), Range)
        {
        }
 
        private IpCidr(IPAddress Address, byte[] Binary, int Range)
        {
            this.address = Address;
            this.binary = Binary;
            this.range = Range;
        }
 
        public IPAddress Address => this.address;
 
        public int Range => this.range;
 
        public static bool TryParse(string s, out IpCidr Parsed)
        {
            s = s.Trim();
 
            int i = s.IndexOf('/');
            int Range = -1;
 
            Parsed = null;
 
            if (i > 0)
            {
                if (!int.TryParse(s.Substring(i + 1), out Range) || Range < 0)
                    return false;
 
                s = s.Substring(0, i);
            }
 
            if (!IPAddress.TryParse(s, out IPAddress Address))
                return false;
 
            byte[] Bin = Address.GetAddressBytes();
            int MaxRange = Bin.Length << 3;
 
            if (Range < 0)
                Range = MaxRange;
            else if (Range > MaxRange)
                return false;
 
            Parsed = new IpCidr(Address, Bin, Range);
 
            return true;
        }
 
        public bool Matches(IPAddress Address)
        {
            if (Address.AddressFamily != this.address.AddressFamily)
                return false;
 
            byte[] Bin = Address.GetAddressBytes();
            int i, c = Math.Min(this.binary.Length, Bin.Length);
            int Bits = this.range;
            byte Mask;
 
            for (i = 0; i < c && Bits > 0; i++, Bits -= 8)
            {
                if (Bits >= 8)
                    Mask = 0xff;
                else
                    Mask = (byte)(0xff << (8 - Bits));
 
                if (((this.binary[i] ^ Bin[i]) & Mask) != 0)
                    return false;
            }
 
            return Bits <= 0;
        }
 
    }
}