online_security_project/lib/Request.cs

namespace lib;

public enum RequestType
{
    Register = 1,
    ConfirmRegister = 2,
    Login = 3,
    GetMessages = 4,
    GetUserKey = 5,
    SendMessage = 6,
}

public static class Request
{
    public static byte[] CreateRequest(RequestType Type, ref byte counter, byte[] data)
    {
        if (data.Length > 13)
        {
            throw new Exception("extra data is too long: " + data.Length.ToString());
        }

        byte[] msg = new byte[16];
        msg[0] = 0; // version
        msg[1] = (byte)Type;
        msg[2] = counter;
        if (counter == byte.MaxValue)
        {
            counter = 0;
        }
        else
        {
            counter += 1;
        }

        // insert data 3..16
        Array.Copy(data, 0, msg, 3, data.Length);
        return msg;
    }

    public static string RequestToString(byte[] Request)
    {
        if (Request.Length != 16)
        {
            throw new Exception("Request size is not 128!");
        }
        string res = $"V: {Request[0]}, ";
        res += $"Request type: {(RequestType)Request[1]}, ";
        res += $"Counter: {Request[2]}\n";
        res += $"Extra: {string.Join(' ', Request[3..].Select(b => b.ToString("{b8}")))}";
        // also display extra data based on the request itself
        switch ((RequestType)Request[1])
        {
            case RequestType.Register:
                string phone = Utils.BytesToNumber(Request[3..11]);
                int rsaLen = BitConverter.ToInt32(Request, 11);
                res += $"Phone: {phone}, RSA Key length: {rsaLen}";
                break;
            case RequestType.ConfirmRegister:
                string code = string.Join(' ', Request[3..9]);
                int sigLen = BitConverter.ToInt32(Request, 9);
                res += $"Code: {code}, signature length: {sigLen}";
                break;
            case RequestType.Login:
                phone = Utils.BytesToNumber(Request[3..11]);
                sigLen = BitConverter.ToInt16(Request, 11);
                res += $"Phone: {phone}, signature length: {sigLen}";
                break;
            case RequestType.GetMessages:
                break;
            case RequestType.GetUserKey:
                break;
            case RequestType.SendMessage:
                break;
            default:
                res += "INVALID REQUEST TYPE";
                break;
        }

        return res;
    }
}