Codecave PrintText

[klusbert]

Hiho!
Okay I am trying to create a codecave inside tibia to print text onscreen.

I know I know this is verry unefficient if you want to add more than 1 text, but this is only for learning purpose.

This is what I've done so far.
http://imgur.com/rJWJUqh

And my code:
http://pastebin.com/p3i7AX3C

I alloc space in memory for my string than I add that into my codeave, as you can see it reads the string correctly in my debugger.

The problem with this is everytime I try to execute it It will crash.

I base my code on this:
http://pastebin.com/B8aDhLkW


Updated to 10.77
Updated to 10.90

[DarkstaR]

Most likely the fact that you're not in sync with the main thread. Also, this would only print that text for a single frame. Also, call is just 0xE9 <offset>. Calculate the function offset by functionAddress - callAddress - 5, or do a PUSH functionAddress, POP eax, CALL eax (that's the way I do it to avoid calculating offsets)

[klusbert]

Thanks Dark, but I dont think it is a sync issue. Because I Replace call printtext in the printfps function as tibiaApi did. Even than it crashes, but If I reset all registers with pop? than call it? I should try to put my function adr in eax than call eax as you said. Do you have a good site for asm code? like 0x6A = push etc.

Thanks again!

[klusbert]

Thanks Darkstar now I figure it out! It is working great The problem was is in the call( as you already pointed out), now I am using 0xe8 now cuz 0xe9 was jmp But as you said offset are kinda annoying
http://imgur.com/IgyUA27

[szulak]

do a PUSH functionAddress, POP eax, CALL eax

Would you mind to explain, what does this trick do?

EDIT:
Nevermind, got it But, shouldn't eax value be saved somewhere? Something like:

push eax
push function address
pop eax
call eax
pop eax
add esp, 4

[Farsa]

Thanks Darkstar now I figure it out! It is working great The problem was is in the call( as you already pointed out), now I am using 0xe8 now cuz 0xe9 was jmp But as you said offset are kinda annoying
http://imgur.com/IgyUA27

wow cipsoft's artists are so bad at concepts, cringy

[Diego]

wow cipsoft's artists are so bad at concepts, cringy

Are you kidding me? thats the Bg img? jeeze. Good thing I retired long ago LOL

[Blequi]

wow cipsoft's artists are so bad at concepts, cringy

Are you kidding me? thats the Bg img? jeeze. Good thing I retired long ago LOL

I think they tried to give a retro look, because it's how cipsoft itself calls tibia. But yeah, I think this background image isn't looking well (looks like a 5 year old child drawing), rather than that I still prefer the image back in 2004~ with a woman in the front.

[klusbert]

Okay I just want to share with you, It is working for me now. So I share a simple project I made.

I wrote it very quickly just to prove that it works.

You can add multiple texts and remove them as you want, you can clear all text.

ps ( you need to recalc the addresses since I am not using aslr.

[astra]

How to update this addresses ? :

private int PrintFps = 0x46e846; //10.20
private int PrintName = 0x4d4d00;
private int ShowFps = 0x96B55A;