NatTypeTester/STUN/Messages/StunAttributeValues/ChangeRequestStunAttributeValue.cs

using Microsoft;
using System;

namespace STUN.Messages.StunAttributeValues;

/// <summary>
/// https://tools.ietf.org/html/rfc5780#section-7.2
/// </summary>
public class ChangeRequestStunAttributeValue : IStunAttributeValue
{
	public bool ChangeIp { get; set; }

	public bool ChangePort { get; set; }

	public int WriteTo(Span<byte> buffer)
	{
		Requires.Range(buffer.Length >= 4, nameof(buffer));

		buffer[0] = buffer[1] = buffer[2] = 0;

		buffer[3] = (byte)(Convert.ToInt32(ChangeIp) << 2 | Convert.ToInt32(ChangePort) << 1);

		return 4;
	}

	public bool TryParse(ReadOnlySpan<byte> buffer)
	{
		if (buffer.Length != 4)
		{
			return false;
		}

		ChangeIp = Convert.ToBoolean(buffer[3] >> 2 & 1);
		ChangePort = Convert.ToBoolean(buffer[3] >> 1 & 1);

		return true;
	}
}