SubjectAlternativeNameBuilder.cs

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using System.Collections.Generic;
using System.Formats.Asn1;
using System.Globalization;
using System.Net;
using System.Security.Cryptography.Asn1;
using System.Text;
 
namespace System.Security.Cryptography.X509Certificates;
 
public sealed class SubjectAlternativeNameBuilder
{
    private static readonly IdnMapping s_idnMapping = new IdnMapping();
 
    private readonly List<byte[]> _encodedNames = new List<byte[]>();
 
    public void AddEmailAddress(string emailAddress)
    {
        if (string.IsNullOrEmpty(emailAddress))
        {
            throw new ArgumentOutOfRangeException("emailAddress", System.SR.Arg_EmptyOrNullString);
        }
        AddGeneralName(new GeneralNameAsn
        {
            Rfc822Name = emailAddress
        });
    }
 
    public void AddDnsName(string dnsName)
    {
        if (string.IsNullOrEmpty(dnsName))
        {
            throw new ArgumentOutOfRangeException("dnsName", System.SR.Arg_EmptyOrNullString);
        }
        AddGeneralName(new GeneralNameAsn
        {
            DnsName = s_idnMapping.GetAscii(dnsName)
        });
    }
 
    public void AddUri(Uri uri)
    {
        if (uri == null)
        {
            throw new ArgumentNullException("uri");
        }
        AddGeneralName(new GeneralNameAsn
        {
            Uri = uri.AbsoluteUri.ToString()
        });
    }
 
    public void AddIpAddress(IPAddress ipAddress)
    {
        if (ipAddress == null)
        {
            throw new ArgumentNullException("ipAddress");
        }
        AddGeneralName(new GeneralNameAsn
        {
            IPAddress = ipAddress.GetAddressBytes()
        });
    }
 
    public void AddUserPrincipalName(string upn)
    {
        if (string.IsNullOrEmpty(upn))
        {
            throw new ArgumentOutOfRangeException("upn", System.SR.Arg_EmptyOrNullString);
        }
        AsnWriter asnWriter = new AsnWriter(AsnEncodingRules.DER);
        asnWriter.WriteCharacterString(UniversalTagNumber.UTF8String, upn);
        byte[] array = asnWriter.Encode();
        OtherNameAsn otherNameAsn = default(OtherNameAsn);
        otherNameAsn.TypeId = "1.3.6.1.4.1.311.20.2.3";
        otherNameAsn.Value = array;
        OtherNameAsn value = otherNameAsn;
        AddGeneralName(new GeneralNameAsn
        {
            OtherName = value
        });
    }
 
    public X509Extension Build(bool critical = false)
    {
        AsnWriter asnWriter = new AsnWriter(AsnEncodingRules.DER);
        using (asnWriter.PushSequence())
        {
            foreach (byte[] encodedName in _encodedNames)
            {
                asnWriter.WriteEncodedValue(encodedName);
            }
        }
        return new X509Extension("2.5.29.17", asnWriter.Encode(), critical);
    }
 
    private void AddGeneralName(GeneralNameAsn generalName)
    {
        try
        {
            AsnWriter asnWriter = new AsnWriter(AsnEncodingRules.DER);
            generalName.Encode(asnWriter);
            _encodedNames.Add(asnWriter.Encode());
        }
        catch (EncoderFallbackException)
        {
            throw new CryptographicException(System.SR.Cryptography_Invalid_IA5String);
        }
    }
}