X509ExtensionAsn.cs

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using System.Formats.Asn1;
using System.Security.Cryptography.X509Certificates;
 
namespace System.Security.Cryptography.Asn1;
 
internal struct X509ExtensionAsn
{
    internal string ExtnId;
 
    internal bool Critical;
 
    internal ReadOnlyMemory<byte> ExtnValue;
 
    private static ReadOnlySpan<byte> DefaultCritical => new byte[3] { 1, 1, 0 };
 
    internal void Encode(AsnWriter writer)
    {
        Encode(writer, Asn1Tag.Sequence);
    }
 
    internal void Encode(AsnWriter writer, Asn1Tag tag)
    {
        writer.PushSequence(tag);
        try
        {
            writer.WriteObjectIdentifier(ExtnId);
        }
        catch (ArgumentException inner)
        {
            throw new CryptographicException(System.SR.Cryptography_Der_Invalid_Encoding, inner);
        }
        AsnWriter asnWriter = new AsnWriter(AsnEncodingRules.DER);
        asnWriter.WriteBoolean(Critical);
        if (!asnWriter.EncodedValueEquals(DefaultCritical))
        {
            asnWriter.CopyTo(writer);
        }
        writer.WriteOctetString(ExtnValue.Span);
        writer.PopSequence(tag);
    }
 
    internal static void Decode(ref System.Formats.Asn1.AsnValueReader reader, ReadOnlyMemory<byte> rebind, out X509ExtensionAsn decoded)
    {
        Decode(ref reader, Asn1Tag.Sequence, rebind, out decoded);
    }
 
    internal static void Decode(ref System.Formats.Asn1.AsnValueReader reader, Asn1Tag expectedTag, ReadOnlyMemory<byte> rebind, out X509ExtensionAsn decoded)
    {
        try
        {
            DecodeCore(ref reader, expectedTag, rebind, out decoded);
        }
        catch (AsnContentException inner)
        {
            throw new CryptographicException(System.SR.Cryptography_Der_Invalid_Encoding, inner);
        }
    }
 
    private static void DecodeCore(ref System.Formats.Asn1.AsnValueReader reader, Asn1Tag expectedTag, ReadOnlyMemory<byte> rebind, out X509ExtensionAsn decoded)
    {
        decoded = default(X509ExtensionAsn);
        System.Formats.Asn1.AsnValueReader asnValueReader = reader.ReadSequence(expectedTag);
        ReadOnlySpan<byte> span = rebind.Span;
        decoded.ExtnId = asnValueReader.ReadObjectIdentifier();
        if (asnValueReader.HasData && asnValueReader.PeekTag().HasSameClassAndValue(Asn1Tag.Boolean))
        {
            decoded.Critical = asnValueReader.ReadBoolean();
        }
        else
        {
            decoded.Critical = new System.Formats.Asn1.AsnValueReader(DefaultCritical, AsnEncodingRules.DER).ReadBoolean();
        }
        if (asnValueReader.TryReadPrimitiveOctetString(out var value))
        {
            decoded.ExtnValue = (span.Overlaps(value, out var elementOffset) ? rebind.Slice(elementOffset, value.Length) : ((ReadOnlyMemory<byte>)value.ToArray()));
        }
        else
        {
            decoded.ExtnValue = asnValueReader.ReadOctetString();
        }
        asnValueReader.ThrowIfNotEmpty();
    }
 
    public X509ExtensionAsn(X509Extension extension)
    {
        if (extension == null)
        {
            throw new ArgumentNullException("extension");
        }
        ExtnId = extension.Oid.Value;
        Critical = extension.Critical;
        ExtnValue = extension.RawData;
    }
}