ASM Community

[*]You tried to make an input buffer, and as i gather it, you wanted it to be 128 bytes in length. A good start, how your declairing the buffer is wrong. Seing LOCAL kb: WORD will only declair 2 bytes (since a word is 2 bytes long). Your on the right track, but you need to make a byte array on the local stack: LOCAL kb[128] :BYTE will do this.
[*]Your actual username and password should have a NULL character as the rest of your stings do. This is so the comparison routines will know where to end.
[*]You understanding of the cmp in general needs work ;) . *i* know what your trying to do by reading this, but the assembler doesnt. To the assembler, the string "cmp word ptr , 'UNa' says: compare the TWO bytes found at the address of EAX, to the THREE ascii bytes 'UNa' (respectively). Well, somehow anyways. Im surprised the assembler actually assembled this with out error. Since your trying to compare two different sizes!. I will show you how to compare strings further on.
[*]Another problem is that your should realize that EAX, ECX, and EDX are NOT transparent thru API calls and in general should NOT assume the same for LIB functions you didnt write ;) . The line lea eax, kb followed by invoke StdOut, ADDR UPass will certainly change the value of EAX as soon as the StdOut function is called!! You can not assume that it will preserved! As well, you can not assume by simply doing the 'LEA' you preserve the infor currently in the buffer, so you can reuse it later. You need make two separate buffers to hold two types of information!
[*]A little for decptive, but the when using the MASM32.LIB routine "StdIn", the text copied into the buffer will have the "13,10" line feed in it. You should call StripLF also found in the MASM32.LIB. It will replace this with a NULL char which will better suit the string comparison routine.


Here is a reworking of your source with new areas in bold:


.486 

.model flat, stdcall 

option casemap :none 



Main proto :DWORD 



include \masm32\include\windows.inc 

include \masm32\include\kernel32.inc 

include \masm32\include\masm32.inc 



includelib \masm32\lib\kernel32.lib 

includelib \masm32\lib\masm32.lib 



.data 

Login db "welCome to Zion Network",13,10,0 

UName db "UserName: ",13,10,0 

UPass db "UserPass: ",13,10,0 

Again db "try again!",13,10,0 

UNa db "k0d"[b],0[/b]

UPa db "love"[b],0[/b]



.data? 

hInstance DWORD ? 



.code 

start: 

[b]push esi

push edi[/b]

invoke GetModuleHandle, NULL 

mov hInstance, eax 

invoke Main, hInstance 

[b]pop edi

pop esi[/b]

invoke ExitProcess, eax 





Main proc hInst:DWORD 

LOCAL kb[b][128] :BYTE

LOCAL kb2[128] :BYTE[/b]



@@: 

invoke ClearScreen 

invoke StdOut, ADDR Login 

invoke StdOut, ADDR UName 

invoke StdIn, ADDR kb, 128 

[b]invoke StripLF, addr kb[/b]



[b]; remove this: lea eax, kb [/b]

invoke StdOut, ADDR UPass 

invoke StdIn, [b]ADDR kb2, 128[/b] 

[b]; remove this: lea ecx, kb 

invoke StripLF, addr kb2[/b]



[b]; remove this : cmp word ptr [eax], 'UNa' 

; This will compare the username

invoke StrLen, addr kb        ; Get the number of bytes entered

mov ecx, eax                  ; Save the count in ECX

mov esi, offset kb            ; Set the SOURCE INDEX to the buffer kb

mov edi, offset UNa           ; Set the DEST INDEX to the UserName seeked

cld                           ; Indicate to count up the byte string

repz cmpsb                    ; repeate comparing the byte at ESI to EDI.

                              ;  If they are the same, ESI = ESI + 1,

                              ;   EDI = EDI +1, and ECX = ECX - 1.

                              ; When finished, ask, is ECX == 0 ?  No? Then

                              ; somewhere the bytes were not the same, since

                              ; not ALL the bytes were checked!

cmp ecx, 0

jne @Error



invoke StrLen, addr kb2       ; Get the number of bytes entered

mov ecx, eax                  ; Save the count in ECX

mov esi, offset kb2           ; Set the SOURCE INDEX to the buffer kb2

mov edi, offset UPa           ; Set the DEST INDEX to the UserPass seeked

cld                           ; Indicate to count up the byte string

repz cmpsb                    ; repeate comparing the byte at ESI to EDI.

                              ;  If they are the same, ESI = ESI + 1,

                              ;   EDI = EDI +1, and ECX = ECX - 1.

                              ; When finished, ask, is ECX == 0 ?  No? Then

                              ; somewhere the bytes were not the same, since

                              ; not ALL the bytes were checked!



cmp ecx, 0

jne @Error

jmp @F



@Error:[/b]

invoke StdOut, ADDR Again 

[b]jmp[/b] @b 



@@: 

xor eax, eax 

ret 

Main endp 



end start 



Anyways, there you go.
Hope you can learn from it ;)
:NaN:

.code

start:

[B]push esi

push edi[/B]

invoke GetModuleHandle, NULL

mov hInstance, eax

invoke Main, hInstance

[B]pop edi

pop esi[/B]

invoke ExitProcess, eax