quantum-space-buddies/EpicOnlineTransport/Packet.cs

using System;

namespace EpicTransport;

public struct Packet
{
	public const int headerSize = sizeof(uint) + sizeof(uint) + 1;
	public int size => headerSize + data.Length;

	// header
	public int id;
	public int fragment;
	public bool moreFragments;

	// body
	public byte[] data;

	public byte[] ToBytes()
	{
		var array = new byte[size];

		// Copy id
		array[0] = (byte)id;
		array[1] = (byte)(id >> 8);
		array[2] = (byte)(id >> 0x10);
		array[3] = (byte)(id >> 0x18);

		// Copy fragment
		array[4] = (byte)fragment;
		array[5] = (byte)(fragment >> 8);
		array[6] = (byte)(fragment >> 0x10);
		array[7] = (byte)(fragment >> 0x18);

		array[8] = moreFragments ? (byte)1 : (byte)0;

		Array.Copy(data, 0, array, 9, data.Length);

		return array;
	}

	public void FromBytes(byte[] array)
	{
		id = BitConverter.ToInt32(array, 0);
		fragment = BitConverter.ToInt32(array, 4);
		moreFragments = array[8] == 1;

		data = new byte[array.Length - 9];
		Array.Copy(array, 9, data, 0, data.Length);
	}
}