Term.cs

using System;
using System.Collections.Generic;
using System.Net;
using Waher.Security.SPF.Mechanisms;
 
namespace Waher.Security.SPF
{
    public enum SpfQualifier
    {
        Pass,
 
        Fail,
 
        SoftFail,
 
        Neutral
    }
 
    public class Term
    {
        internal string s = null;
        internal int len = 0;
        internal int pos = 0;
        internal int dnsLookupsLeft = 10;
        internal readonly string sender;
        internal string domain;
        internal readonly string helloDomain;
        internal readonly string hostDomain;
        internal readonly IPAddress ip;
 
        public Term(string Sender, string Domain, IPAddress Ip, string HelloDomain,
            string HostDomain)
        {
            this.sender = Sender;
            this.domain = Domain;
            this.ip = Ip;
            this.helloDomain = HelloDomain;
            this.hostDomain = HostDomain;
        }
 
        public void Reset(string String)
        {
            this.s = String?.Trim() ?? string.Empty;
            this.len = this.s.Length;
            this.pos = 0;
        }
 
        internal void SkipWhiteSpace()
        {
            while (this.pos < this.len && this.s[this.pos] <= ' ')
                this.pos++;
        }
 
        internal char PeekNextChar()
        {
            if (this.pos >= this.len)
                return (char)0;
            else
                return this.s[this.pos];
        }
 
        internal char NextChar()
        {
            if (this.pos >= this.len)
                throw new Exception("SPF syntax error.");
 
            return this.s[this.pos++];
        }
 
        internal int NextInteger()
        {
            int Start = this.pos;
 
            while (char.IsDigit(this.PeekNextChar()))
                this.pos++;
 
            return int.Parse(this.s.Substring(Start, this.pos - Start));
        }
 
        internal string NextLabel()
        {
            int Start = this.pos;
            char ch;
 
            if (char.IsLetter(ch = this.PeekNextChar()))
            {
                this.pos++;
 
                while (char.IsLetter(ch = this.PeekNextChar()) || char.IsDigit(ch) ||
                    ch == '-' || ch == '_' || ch == '.')
                {
                    this.pos++;
                }
            }
 
            return this.s.Substring(Start, this.pos - Start);
        }
 
    }
}