Lazarus

Programming => General => Topic started by: pcurtis on October 23, 2020, 01:24:10 pm

Title: [SOLVED] Code trouble
Post by: pcurtis on October 23, 2020, 01:24:10 pm

Hi All,

I am using nxnetwork.pas in a little program I am creating.

It allows to set a "key" to be used with TCP communication.

When I set the key string to '' the program runs fine but as soon as I use a key the program fails here

Code: Pascal  [Select][+][-]

1. procedure TConnection.MaskCrypt(p: {$IFDEF fpc}PByte{$ELSE}PByteArray{$ENDIF};
2.   size: integer);
3. var i, l: integer;
4. begin
5.   l := length(FMask);
6.   if l<1 then exit;
7.   for i := 0 to size-1 do p[i] := p[i] xor byte(FMask[(i mod l)+1]);
8. end;
9.  

I get a SIGSEGV.

Can anyone tell me how to fix this?

Title: Re: Code trouble
Post by: bytebites on October 23, 2020, 02:23:28 pm

Again guessing topic #12131.
How it is so hard to give compilable code?

Run your program in debug mode with range check on.

Title: Re: Code trouble
Post by: pcurtis on October 23, 2020, 04:27:15 pm

OK. I've expanded the code -

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Button1 : TButton;
16.     procedure Button1Click(Sender : TObject);
17.   private
18.  
19.   public
20.  
21.   end;
22.  
23. var
24.   Form1 : TForm1;
25.  
26. const
27.   fMask = 'abcd';
28.  
29. implementation
30.  
31. {$R *.lfm}
32.  
33. { TForm1 }
34.  
35. procedure MaskCrypt(p: {$IFDEF fpc}PByte{$ELSE}PByteArray{$ENDIF};
36.                     size: integer);
37. var i,
38.     l : integer;
39. begin
40.   l := length(FMask);
41.   if l < 1 then exit;
42.   for i := 0 to size - 1 do p[i] := p[i] xor byte(FMask[(i mod l) + 1]);
43. end;
44.  
45. procedure TForm1.Button1Click(Sender : TObject);
46. var
47.   s : string;
48. begin
49.   s := 'test';
50.  
51.   MaskCrypt(@s[1], length(s));
52. end;
53.  
54. end.
55.  
56.  

Title: Re: Code trouble
Post by: jamie on October 23, 2020, 05:00:36 pm

Try using UniqueString(S) before passing it to the function.

Title: Re: Code trouble
Post by: bytebites on October 23, 2020, 06:32:00 pm

or don't use pchar:

Code: Pascal  [Select][+][-]

1. procedure MaskCrypt(var s:string);
2. var i,
3.     l : integer;
4. begin
5.   l := length(FMask);
6.   if l < 1 then exit;
7.   for i := 1 to Length(s) do s[i] := chr(ord(s[i]) xor ord(FMask[(i mod l) + 1]));
8. end;  

Title: Re: Code trouble
Post by: pcurtis on October 23, 2020, 07:21:35 pm

OK. Thanks.