NetAddress.cs

﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace Hosts
{
	public enum NetAddressType { None, IPv4, IPv6 };

	public class NetAddress
	{
		private string IP;

		public NetAddressType Type { get; protected set; }

		/// <summary>
		/// Normalize IPv6 address to compact format
		/// </summary>
		/// <param name="ip">IPv6 string</param>
		/// <returns>Normalized IPv6 string</returns>
		protected string NormalizeIPv6(string ip)
		{
			var hex = ip.Split(':');
			var dec = new uint[8];
			var gap = false;

			// Parse "head"
			for (var i = 0; i < hex.Length; i++)
			{
				if (String.IsNullOrEmpty(hex[i]))
				{
					gap = true;
					break;
				}
				dec[i] = Convert.ToUInt32(hex[i], 16);
			}

			// Parse "tail"
			if (gap) for (var i = 0; i < hex.Length; i++)
			{
				if (String.IsNullOrEmpty(hex[hex.Length - i - 1]))
				{
					break;
				}
				dec[dec.Length - i - 1] = Convert.ToUInt32(hex[hex.Length - i - 1], 16);
			}


			// Find longest zeroes part
			var max_offset = -1;
			var max_length = 0;
			var offset = -1;
			var length = 0;

			for (var i = 0; i < dec.Length; i++)
			{
				if (dec[i] == 0)
				{
					if (offset == -1)
					{
						offset = i;
						length = 1;
					}
					else
					{
						length++;
					}
				}
				else if (offset > -1)
				{
					if (length > max_length)
					{
						max_offset = offset;
						max_length = length;
					}
					offset = -1;
					length = 0;
				}
			}
			if (length > max_length)
			{
				max_offset = offset;
				max_length = length;
			}

			// Ignore one zero
			if (max_length == 1)
			{
				max_length = 0;
				max_offset = -1;
			}

			// Format normalized IPv6 address
			ip = "";
			for (int i = 0; i < dec.Length; i++)
			{
				if (i >= max_offset && i < (max_offset + max_length))
				{
					if (i == max_offset)
					{
						ip += "::";
					}
					continue;
				}

				if (ip.Length > 0 && !ip.EndsWith(":"))
				{
					ip += ":";
				}

				ip += dec[i].ToString("x");
			}

			return ip.ToLower();
		}

		public NetAddress(string ip)
		{
			if (ip == null) throw new ArgumentNullException();
			try
			{
				var parsed = IPAddress.Parse(ip);
				switch (parsed.AddressFamily)
				{

					case AddressFamily.InterNetwork:
						Type = NetAddressType.IPv4;
						IP = parsed.ToString();
					break;

					case AddressFamily.InterNetworkV6:
						Type = NetAddressType.IPv6;
						IP = NormalizeIPv6(ip);
					break;

					default: throw new Exception();
				}
			}
			catch
			{
				throw new FormatException(String.Format("Invalid IP address '{0}'", IP));
			}
		}

		public static NetAddress TryCreate(string ip)
		{
			try { return new NetAddress(ip); }
			catch { return null; }
		}

		public static implicit operator NetAddress(string ip)
		{
			return new NetAddress(ip);
		}

		public static implicit operator string(NetAddress ip)
		{
			return ip.ToString();
		}

		public override string ToString()
		{
			return IP;
		}

		public override int GetHashCode()
		{
			return ToString().GetHashCode();
		}

		public bool Equals(NetAddress ip)
		{
			if ((object)ip == null) return false;
			return ip.IP == this.IP;
		}

		public bool Equals(string ip)
		{
			return Equals(NetAddress.TryCreate(ip));
		}

		public override bool Equals(object obj)
		{
			if (obj == null) return false;
			if (obj is string) return Equals((string)obj);
			if (obj is NetAddress) return Equals((NetAddress)obj);
			return false;
		}

		public static bool operator ==(NetAddress na1, NetAddress na2)
		{
			return Object.ReferenceEquals(na1, na2) || na1.Equals(na2);
		}

		public static bool operator !=(NetAddress na1, NetAddress na2)
		{
			return !(Object.ReferenceEquals(na1, na2) || na1.Equals(na2));
		}
	}
}