Ip.cs

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading.Tasks;
 
namespace Waher.Security.SPF.Mechanisms
{
    public abstract class Ip : Mechanism
    {
        protected IPAddress address;
 
        protected int cidr;
 
        public Ip(Term Term, SpfQualifier Qualifier)
            : base(Term, Qualifier)
        {
            if (Term.PeekNextChar() != ':')
                throw new Exception(": expected.");
 
            Term.NextChar();
 
            int Start = Term.pos;
            char ch;
 
            while (Term.pos < Term.len && (ch = Term.s[Term.pos]) != '/' && ch > ' ')
                Term.pos++;
 
            if (!IPAddress.TryParse(Term.s.Substring(Start, Term.pos - Start), out this.address))
                throw new Exception("IP Address expected.");
 
            int Max;
 
            switch (this.address.AddressFamily)
            {
                case AddressFamily.InterNetwork:
                    Max = 32;
                    break;
 
                case AddressFamily.InterNetworkV6:
                    Max = 128;
                    break;
 
                default:
                    throw new Exception("IP Address expected.");
            }
 
            if (Term.PeekNextChar() == '/')
            {
                Term.NextChar();
 
                this.cidr = Term.NextInteger();
                if (this.cidr < 0 || this.cidr > Max)
                    throw new Exception("Invalid CIDR");
            }
            else
                this.cidr = Max;
        }
 
        public override Task<SpfResult> Matches()
        {
            bool Result = MechanismDomainCidrSpec.Matches(new IPAddress[] { this.address }, this.term, this.cidr);
            return Task.FromResult<SpfResult>(Result ? SpfResult.Pass : SpfResult.Fail);
        }
 
    }
}