GeneralName.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Formats.Asn1;
using System.Net;
 
namespace NeuroAccess.Nfc.TravelDocuments.Security.Properties
{
    public abstract class GeneralName : SecurityObject
    {
        private object? name;
 
        public override bool Configure(Vector SecurityInfo)
        {
            if (SecurityInfo.Length != 2)
                return false;
 
            object? Last = SecurityInfo.LastElementNested;
 
            if (Last is Vector Context)
                return TryParse(Context, out this.name);
            else if (Last is byte[] BinName)
            {
                this.name = BinName;
                return true;
            }
            else if (Last is Array A && A.Length == 0)
            {
                this.name = string.Empty;
                return true;
            }
            else
                return false;
        }
 
        public override bool IsConfigured => this.name is not null;
 
        public object? Name => this.name;
 
        public static bool TryParse(Vector ParsedVector, [NotNullWhen(true)] out object? Name)
        {
            object? First = ParsedVector.FirstElement;
            Name = null;
 
            if (First is not byte[] GeneralName)
            {
                while (First is Vector v && v.Length == 1)
                {
                    ParsedVector = v;
                    First = ParsedVector.FirstElement;
                }
 
                if (First is byte[] GeneralName2)
                    GeneralName = GeneralName2;
                else if (First is Vector v &&
                    v.Length > 0 &&
                    v.FirstElement is byte[] GeneralName3)  // First is absolute name, second a relative name
                {
                    GeneralName = GeneralName3;
                }
                else
                {
                    Name = ParsedVector;
                    return true;
                }
            }
 
            if (GeneralName.Length == 0)
                return false;
 
            switch (GeneralName[0])
            {
                case 0x83:  // ORAddress
                case 0x85:  // EDIPartyName
                    return ASN1.TryDecodeDerAs(UniversalTagNumber.Sequence, GeneralName, out Name);
 
                case 0x84:  // Name
                    Name = GeneralName;
                    return true;
 
                case 0x81:  // IA5String
                case 0x82:
                case 0x86:
                    return ASN1.TryDecodeDerAs(UniversalTagNumber.IA5String, GeneralName, out Name);
 
                case 0x80:  // OtherName
                    return ASN1.TryDecodeDerAs(UniversalTagNumber.OctetString, GeneralName, out Name);
 
                case 0x87:  // IpAddress
                    if (!ASN1.TryDecodeDerAs(UniversalTagNumber.OctetString, GeneralName, out Name))
                        return false;
 
                    if (Name is byte[] BinIpAddress)
                        Name = new IPAddress(BinIpAddress);
                    else if (Name is null)
                        return false;
 
                    return true;
 
                case 0x88:
                    return ASN1.TryDecodeDerAs(UniversalTagNumber.ObjectIdentifier, GeneralName, out Name);
 
                default:
                    return false;
            }
        }
    }
}