Question

I have a record:

  Tconnecting = record
  var
    a: int64;
    b: integer;
    c: integer;
  end;

which I need send to server using UDP protocol

I fill it

  packet.a := StrToInt64('0x1234567890');
  packet.b := 0;
  packet.c := RandomRange(1, 9999999);

and sending it

  SetLength(send_data, sizeof(packet));
  send_data := RawToBytes(packet, SizeOf(packet));
  udp.SendBuffer(make_it_big_endian(send_data)); <-- the question... "network byte order"

or maybe I’m doing something wrong? I need to send “bign endian” packet

pack("N*", int64, int, int); (this is in PHP)

Thanks.

Answer 1

Assuming your code is running in a little-endian OS/Machine (like Windows/Intel), you can just reverse the individual bytes of your packet, for example, include the FMX.Types unit in your uses clause:

type
  Tconnecting = record
    a: int64;
    b: integer;
    c: integer;
  end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Packet, BEPacket: Tconnecting;
begin
  packet.a := $0102030405060708;
  packet.b := $01020304;
  packet.c := $05060708;
  //big endian packet  
  BEPacket := Packet;

  ReverseBytes(@BEPacket.a, SizeOf(BePacket.a));
  ReverseBytes(@BEPacket.b, SizeOf(BePacket.b));
  ReverseBytes(@BEPacket.c, SizeOf(BePacket.c));

  Memo1.Lines.Add(Format('a: %16.16x => %16.16x', [Packet.a, BEPacket.a]));
  Memo1.Lines.Add(Format('b: %8.8x => %8.8x', [Packet.b, BEPacket.b]));
  Memo1.Lines.Add(Format('c: %8.8x => %8.8x', [Packet.c, BEPacket.c]));
end;