protocol constants enums

[mkalex777]

I'm not sure, is there something stopping to use standard enums instead of int/short/byte consts?

Using enum make life much more easier. It's performance free and you can freely use it since it was supported from the first version of C#.

For example:

    public enum ExtensionType : ushort
    {
        /*
         * RFC 2546 2.3.
         */
        server_name = 0,
        max_fragment_length = 1,
        client_certificate_url = 2,
        trusted_ca_keys = 3,
        truncated_hmac = 4,
        status_request = 5,

        renegotiation_info = 0xff01,
}

when you needs to pass it as int, just add explicit cast:

   ExtensionType type = ExtensionType.max_fragment_length;
   Console.WriteLine("{0} = {1}", type, (int)type);
   
   type = (ExtensionType)77777777;
   Console.WriteLine("{0} = {1}", type, (int)type);

max_fragment_length = 1
77777777 = 77777777

By default enum is derived from int, but in case of needs you can derive it from byte or ushort:

    public enum ContentType : byte
    {
        change_cipher_spec = 20,
        alert = 21,
        handshake = 22,
        application_data = 23,
        heartbeat = 24,

I notice that a new src/tls code has switched from byte to short for ContentType. Is there reason for that? According to the TLS protocol it takes just one byte. Isn't it?