DllCall problem

[CoePSX]

I made this little DLL, and compiled it under MinGW. It's very very simple, just rotates the bits of a string.

AutoIT calls the function, as it shows with the MessageBox, but it can't read the return value of it.

This is the DLL Code:

expandcollapse popup

#include <windows.h>
#include <string.h>
#include <stdio.h>

#ifdef BUILD_DLL
    #define DLL_EXPORT __declspec(dllexport)
#else
    #define DLL_EXPORT
#endif

LPCSTR DLL_EXPORT EncryptString (LPCSTR, LPCSTR);
LPCSTR DLL_EXPORT DecryptString (LPCSTR, LPCSTR);
byte bitrotate (byte, int);

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved) {
    //
}

// Encrypt a string //
LPCSTR DLL_EXPORT EncryptString (LPCSTR sString, LPCSTR sPasswd) {
    MessageBox (NULL, sString, "Test", MB_OK);
    int iKey = 0;
    int i = 0;
    int j = 0;
    byte bTemp;
    char sFinal[strlen(sString)+1];

    // Calculates the key number from the password //
    for (i=0; i<strlen(sPasswd); i++) {
        iKey ^= sPasswd[i];
    }

    // Now rotate the bits acording to the key bits
    for (i=0; i<strlen(sString); i++) {
        bTemp = (char)sString[i];
        for (j=0;j<8;j++) {
            if (((byte)iKey & (1 << j)) != 0)
                bTemp = bitrotate(bTemp, 2);
            else
                bTemp = bitrotate(bTemp, 1);
        }
        sFinal[i] = bTemp;
    }
    sFinal[strlen(sString)] = '\0';

    MessageBox (NULL, sFinal, "Test", MB_OK);
    return (LPCSTR)sFinal;
}

// Decrypt a string //
LPCSTR DLL_EXPORT DecryptString (LPCSTR sString, LPCSTR sPasswd) {
    int iKey = 0;
    int i = 0;
    int j = 0;
    byte bTemp;
    char sFinal[strlen(sString)+1];

    // Calculates the key number from the password //
    for (i=0; i<strlen(sPasswd); i++) {
        iKey ^= sPasswd[i];
    }

    // Now rotate the bits acording to the key bits
    for (i=0;i<strlen(sString);i++) {
        bTemp = (char)sString[i];
        for (j=0;j<8;j++) {
            if (((byte)iKey & (1 << j)) != 0)
                bTemp = bitrotate(bTemp, -2);
            else
                bTemp = bitrotate(bTemp, -1);
        }
        sFinal[i] = bTemp;
    }
    sFinal[strlen(sString)] = '\0';

    return (LPCSTR)sFinal;
}

byte bitrotate (byte iByte, int iTimes) {
    byte iTemp;
    int i;

    if (iTimes > 0) {
        for (i=0;i<iTimes;i++) {
            iTemp = iByte & 1;
            iByte >>= 1;
            if (iTemp==1)
                iByte |= 128;
            else
                iByte &= 127;
        }
    }
    else if (iTimes < 0) {
        for (i=0;i>iTimes;i--) {
            iTemp = iByte & 128;
            iByte <<= 1;
            if (iTemp==128)
                iByte |= 1;
            else
                iByte &= 254;
        }
    }
    return iByte;
}

And the AutoIT code:

$DLL = @ScriptDir & "\coecrypt.dll"

$Encrypted = DllCall($DLL, "str", "EncryptString", "str", "test string", "str", "password")
MsgBox(0, "DEBUG", $Encrypted)

I'd be glad if anyone could help me, cause i have no idea what to do now .

Thanks in advance.

[CoePSX]

$Encrypted[0] = "$)D"

$Excrypted[1] and $Encrypted[2] are the arguments, "test string" and "password"

That already helps me alot! Now I only need to uderstand why $Encrypted[0] is so strange... but i'll mess with it to see if i get it.

Thank you very much Larry!!

[CoePSX]

With any string it gives me always "$)D", and the length is always 3.

=/

[CoePSX]

Thanks! I'll try to remove the nulls.

[CoePSX]

I fixed the problem by doing this:

// Encrypt a string //
const char* DLL_EXPORT EncryptString (const char* sString, const char* sPasswd) {
    //MessageBox (NULL, sString, "Test", MB_OK);
    int iKey = 0;
    int i = 0;
    int j = 0;
    byte bTemp;
    char* sFinal;

    // Calculates the key number from the password //
    for (i=0; i<strlen(sPasswd); i++) {
        iKey ^= sPasswd[i];
    }

    // Now rotate the bits acording to the key bits
    for (i=0; i<strlen(sString); i++) {
        bTemp = (char)sString[i];
        for (j=0;j<8;j++) {
            if (((byte)iKey & (1 << j)) != 0)
                bTemp = bitrotate(bTemp, 2);
            else
                bTemp = bitrotate(bTemp, 1);
        }
        sFinal[i] = bTemp;
    }
    sFinal[strlen(sString)] = '\0';

    return sFinal;
}

Without the NULL at the end it would return strange chars after the end of the string.

[piccaso]

"str" is valid as return value?

... well it looks like

does autoit free it after reading the contents?

[JSThePatriot]

Just out of curiosity, why would you make an actual DLL file when you could make an AutoIt Plugin DLL that would I think make things a bit easier in the your code.

Of course this is coming from someone that hasnt yet used DLLCall()

JS

[Richard Robertson]

Why haven't you used DLLCall?

An AutoIt Plugin DLL is an actual DLL.

[CoePSX]

Ahm... I'm trying to learn C++. That was just an attempt to learn to make DLLs.

Just a little stupid question off-topic. Actually two...

What's the difference between s and sz in variable prefixes, like sName and szName?

And why is there "2 ^ 128" in IceKirby1's sig, when 2 ^ 128 means 2 BitXOR 128?

Edited September 15, 2006 by CoePSX

[JSThePatriot]

Why haven't you used DLLCall?

An AutoIt Plugin DLL is an actual DLL.

Actually havent seen the need in any of my scripts yet. I havent done anything crazy or off the wall I guess. Just using built in functions, and built my own plugin when I needed File/String Hashes (MD5, SHA-1)

Yea I know an AutoIt Plugin is an actual DLL, I have created one. They are a bit easier to use in the syntax in AutoIt though.

JS

[nfwu]

What's the difference between s and sz in variable prefixes, like sName and szName?

I don't think there is any difference.

But i usually use sz for C++ null-terminated strings and str for the std library strings.

And why is there "2 ^ 128" in IceKirby1's sig, when 2 ^ 128 means 2 BitXOR 128?

That's not the C++ operator ^. That's the mathematical operator ^. It means to the power of.

#)

[JSThePatriot]

I don't think there is any difference.

But i usually use sz for C++ null-terminated strings and str for the std library strings.

That's not the C++ operator ^. That's the mathematical operator ^. It means to the power of.

#)

What does the z stand for? The sound of "strings" being "stringz"?

JS

[Valik]

Using sz means the string is zero-terminated. It's a C-style string. Using just "s" means the string is probably not zero-terminated. For example, if you were to use MFC's CString class or STL's std::string, you would not use szName but rather sName.

Search for "Hungarian Notation" for more information on the prefixes and what they generally mean.

[CoePSX]

XD that's why i think 'sz' so weird.

Edit: Thanks Valik, hadn't seen your post when i posted.

Edited September 25, 2006 by CoePSX

[JSThePatriot]

Using sz means the string is zero-terminated. It's a C-style string. Using just "s" means the string is probably not zero-terminated. For example, if you were to use MFC's CString class or STL's std::string, you would not use szName but rather sName.

Search for "Hungarian Notation" for more information on the prefixes and what they generally mean.

Thanks Valik! I appreciate it. I will certainly do that.

JS

[Richard Robertson]

Yes, I am using the BASIC ^ to-the-power-of symbol, not the XOR symbol. Why did you ask that way? Why not ask "Icekirby1, why is that symbol in your sig" instead of making a reference to me in what I think is the second person.

I've always wondered what sz meant. I rarely use it in my own code, but no one really sees it so it doesn't matter.

[CoePSX]

Sorry about that Icekirby1. It was just a way of asking.