Re: Get ASCII value for character when higher than 127

From:
MrAsm <mrasm@usa.com>
Newsgroups:
microsoft.public.vc.language
Date:
Tue, 05 Jun 2007 16:02:02 GMT
Message-ID:
<121b639rdh6dsgahku5d7f5mnv37o5ihe1@4ax.com>
On Tue, 05 Jun 2007 07:25:22 -0700, ssetz@wxs.nl wrote:

For a while, I thought everything worked fine, but now I'm running
into a really weird problem. In some cases, the XOR on the '\0'


In addition to what I've written my previous post, I think that your
C++ code may have other problems...

string GetPwdFilePath()
{
    const char* timeStringFormat = "%Y-%m-%d_%H-%M-%S";
    const size_t timeStringLength = 20;
    char timeString[timeStringLength] = { 0 };
    time_t t = time(0);
    tm *curTime = localtime(&t);
    strftime(timeString, timeStringLength,
        timeStringFormat, curTime);

    string path("C:\\PwdSync\\pwds\\");
    path.append(timeString);
    path.append(".pwd");

    free(timeString);
******
This is an error.
timeString is allocated in the stack, not in the heap.
So, you must not 'free' it.

BTW: I've not VC++2005, but I thought that it could prevent such
memory leaks/corruption. Didn't VC++ signaled you anything about that?
(I'm aware that the VC++ software engineers did a great job for the
compiler.)

******

string GetLogFilePath()
{

....

  free(timeString);

******

Another invalid 'free' here.

******

string ObfuscateUnicodeString(LPCWSTR pwszIn, USHORT nLen)
{
    ostringstream oss;
    oss << right;

    int k = GetNextXORVal(0);
    for(size_t i = 0; i < nLen; ++i)
    {
        int ch = pwszIn[i]^k;
        k = GetNextXORVal(k) ;

        oss << setw(7) << setfill('0') << ch;
    }
    string result = oss.str();
    oss.clear();
******
oss.clear() is useless here: ostringstream destructor should clear
everything.

******

void WriteMessage(
    const string& path,
    const string& username,
    const string& password,
    const string& seperator
)
{
    ofstream outPwd(path.c_str());

******

Add std::ios_base::binary as I've written in my previous post.

******

    outPwd << username << seperator << password ;
    outPwd.close();
}

******
 .close() useless here.

******

     ofstream outPwd(path.c_str(), ios::app);
    if (!outPwd)
    {
        ofstream outPwd(path.c_str(), ios::out );
    }

    outPwd << timeString << " - " << logmsg << username << "\n";
   outPwd.close();
    free(timeString);
}

******

- Add binary flag to ofstream.
- Could remove outPwd.close()
- Must remove free(timeString).

******

NTSTATUS
NTAPI
PasswordChangeNotify(
    PUNICODE_STRING UserName,
    ULONG RelativeId,
    PUNICODE_STRING Password
)
{
    char *usernameStr;
    usernameStr = (char*)calloc(1, (UserName->Length/2)+1);
    wcstombs(usernameStr, UserName->Buffer, (UserName->Length/2));
******

I don't trust this code very much...

If you want to know the size of destination buffer and dynamically
allocate it, you should call wcstombs with first parameter NULL, i.e.

 size_t requiredSize = wcstombs(NULL, UserName->Buffer, ...
 
 char * userNameStr = new char[ requiredSize ];

 // Then release the buffer using delete[]

We are in C++ world, why do you use malloc/calloc instead of new?

Moreover, I would use the safe version wcstombs_s instead of
deprecated wcstombs...

******

     const string& logpath = GetLogFilePath();
******

Why the string reference?
Why not just 'const string logpath = ...' ?

******

     const string& username = ObfuscateUnicodeString(UserName->Buffer,
(UserName->Length /2) + 1);
   const string& password = ObfuscateUnicodeString(Password->Buffer,
(Password->Length /2) + 1);
   const string& seperator = ObfuscateUnicodeString(PSeperator-

Buffer, PSeperator->Length);

   const string& path = GetPwdFilePath();

******

I don't understand why you use the 'const string &' here instead of
'const string'...

******

MrAsm

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