MWF2 RCON TOOL Communication with delphi using indyUDP - delphi

Question

Modern Warefare 2 (MWF2): is a Video game.
RCON TOOL: is a tool used to send commands to Game servers using UDP.
i am trying to send a command using indy to a server, its easy to send some string using idUDPclient but my Problem is that
i supposed to send it in this format:
ÿÿÿÿrcon "1234" kick cheater101
where :-
password quoted: "1234"
and command is : kick cheater101
as byte like this
FFFFFFFF72636F6E2020223132333422206B69636B2063686561746572313031
notice that anything sent must start with FFFFFFFF
and that how it should look in Wireshark..
the problem is i couldn't send it like the above .. i just sent like a string ..
i need to make it with indyUDP because I'm planning to test it on android.
here is my code for i am trying:
function rcon(const IP: String; Port: TIdPort; const Pass, Command: String): String;
var
Query: TIdBytes;
Buffer, Data:
TIdBytes;
Len: Integer;
begin
SetLength(Query, 4);
Query[0] := $FF;
Query[1] := $FF;
Query[2] := $FF;
Query[3] := $FF;
AppendString(Query, 'rcon "' + Pass + '" ' + Command);
SetLength(Data, 0);
with TIdUDPClient.Create do try ReceiveTimeout := 2000;
SendBuffer(IP, Port, Query);
repeat SetLength(Buffer, 10000);
Len := ReceiveBuffer(Buffer);
if Len < 1 then Break;
SetLength(Buffer, Len);
AppendBytes(Data, Buffer);
until False; finally Free;
end; // preprocess Data as needed... Result := BytesToString(Data);
end
usage!
rcon('10.0.0.4', 28961, '1234', 'kick cheater101');
Wireshark:

Answer 1

You are encountering a DISPLAY issue, not a DATA issue. In your Wireshark screenshot, you are looking at the raw bytes as-is, not at the hex formatted representation of those same bytes. Wireshark can show you both.
The actual bytes you are sending are fine - except that you are missing a 2nd space character between rcon and the quoted password.
function rcon(const IP: String; Port: TIdPort; const Pass, Command: String): String;
var
Query: TIdBytes;
Buffer, Data: TIdBytes;
Len: Integer;
begin
SetLength(Query, 4);
FillBytes(Query, 4, $FF);
AppendString(Query, 'rcon "' + Pass + '" ' + Command);
SetLength(Data, 0);
with TIdUDPClient.Create do
try
SendBuffer(IP, Port, Query);
ReceiveTimeout := 2000;
SetLength(Buffer, 10000);
repeat
Len := ReceiveBuffer(Buffer);
if Len < 1 then Break;
AppendBytes(Data, Buffer, 0, Len);
until False;
finally
Free;
end;
// preprocess Data as needed...
Result := BytesToString(Data);
end;
Also, in your Wireshark screenshot, it clearly shows 70 bytes being sent for each command, where the command itself is 32 bytes and the rest is 38 bytes of padding. If the server is expecting that padding, you need to add it to your outgoing Query:
function rcon(const IP: String; Port: TIdPort; const Pass, Command: String): String;
var
Query: TIdBytes;
Buffer, Data: TIdBytes;
Len: Integer;
begin
SetLength(Query, 4);
FillBytes(Query, 4, $FF);
AppendString(Query, 'rcon "' + Pass + '" ' + Command);
if (Length(Query) < 70) then
ExpandBytes(Query, Length(Query), 70-Length(Query));
SetLength(Data, 0);
with TIdUDPClient.Create do
try
SendBuffer(IP, Port, Query);
ReceiveTimeout := 2000;
SetLength(Buffer, 10000);
repeat
Len := ReceiveBuffer(Buffer);
if Len < 1 then Break;
AppendBytes(Data, Buffer, 0, Len);
until False;
finally
Free;
end;
// preprocess Data as needed...
Result := BytesToString(Data);
end;

Answer 2

this works, well it will return the proper byte array (as an AnsiString, anyways)!. I used format to combine the inputs, and prepended the FFFFFFFFs
Function MakeKickCommand(pass, user: LPCSTR): AnsiString; //is wide strings okay
var
Temp : AnsiString;
len, I: integer;
a: integer;
Begin
Temp:= AnsiString( format('rcon "%s" kick %s', [pass, user]) );
len := length(Temp);
//set length of the result
SetLength(Result, 4+len);
//add FF FF FF FF
FillChar (Result[1], 4, $FF);
//copy the formatted string
Move(Temp[1], Result[5], len);
End;