FromIp.cs

using System;
using System.Net;
using System.Threading.Tasks;
using System.Xml;
using Waher.Content.Xml.Attributes;
using Waher.Networking.HTTP.Interfaces;
using Waher.Runtime.IO;
 
namespace Waher.Security.WAF.Model.Comparisons
{
    public class FromIp : WafComparison
    {
        private readonly StringAttribute value;
 
        public FromIp()
            : base()
        {
        }
 
        public FromIp(XmlElement Xml, WafAction Parent, WebApplicationFirewall Document)
            : base(Xml, Parent, Document)
        {
            this.value = new StringAttribute(Xml, "value");
        }
 
        public override string LocalName => nameof(FromIp);
 
        public override WafAction Create(XmlElement Xml, WafAction Parent, WebApplicationFirewall Document) => new FromIp(Xml, Parent, Document);
 
        public override async Task<WafResult?> Review(ProcessingState State)
        {
            string Endpoint = State.Request.RemoteEndPoint.RemovePortNumber();
 
            if (!IPAddress.TryParse(Endpoint, out IPAddress Address))
                return null;
 
            string Value = await this.value.EvaluateAsync(State.Variables, string.Empty);
            string Key = Endpoint + "|IP|" + Value;
 
            if (!State.TryGetCachedObject(Key, out bool IsMatch))
            {
                IsMatch = CheckMatch(Address, Value);
                State.AddToCache(Key, IsMatch, fiveMinutes);
            }
 
            return IsMatch ? await this.ReviewChildren(State) : null;
        }
 
        private static bool CheckMatch(IPAddress Value, string List)
        {
            string[] Items = List.Split(',', StringSplitOptions.RemoveEmptyEntries);
 
            foreach (string Item in Items)
            {
                string s = Item.Trim();
 
                if (s.Contains('/'))
                {
                    if (IpCidr.TryParse(s, out IpCidr Cidr) && Cidr.Matches(Value))
                        return true;
                }
                else if (IPAddress.TryParse(s, out IPAddress Addr))
                {
                    if (Addr.Equals(Value))
                        return true;
                }
            }
 
            return false;
        }
    }
}