Question

I’m making a webserver and I’ve come up with some very strange problems.

1. My server was running as expected
   yesterday when I turned off my laptop, but today it only sends the http
   headers (I didn’t change anything)
2. When a user requests a file, if I send them using the following code, it works perfectly:

while ((n = fread(data, 1, sizeof(data), file)) > 0)
send(ts, data, n, 0);

but if I change it to this, it only sends ~2% of the file. And that’s not a random number, it actually only sends about 2% of the file.

while ((n = fread(data, 1, sizeof(data), file)) > 0)
web.Send(data);

int WEB::Send(string data)
{
    return send(TempSocket, data.c_str(), data.size(), 0);
}

changing string to char* doesn’t solve the problem.

• I’m using visual studio2010. If I run
  my code step-by-step, I am able to
  solve problem #1, everything gets sent. And that is my main
  problem. I do not understand why it
  happens. Hopefully someone can
  explain it to me.

Thanks in advance.

EDIT:

int APIENTRY WinMain( HINSTANCE hInstance, HINSTANCE hPrev, LPSTR lpCmd,int nShow)
{
    SOCKET MainSocket=0;
    MSG msg;


    RedirectIOToConsole();





    CreateThread(NULL, NULL, ListenThread, NULL, NULL, NULL);



    while (GetMessage(&msg, NULL, 0, 0)) 
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }


    WSACleanup();
    closesocket(MainSocket);
    MainSocket = INVALID_SOCKET;

    return msg.wParam;
}

DWORD WINAPI ListenThread(LPVOID lparam)
{
    SOCKET MainSocket;
    WSADATA wsaData;
    SOCKET tmpsock;
    struct sockaddr_in local, from;
    int fromlen=sizeof(from);

    WSAStartup(MAKEWORD(2, 2), &wsaData);


    local.sin_family=AF_INET;
    local.sin_addr.s_addr=INADDR_ANY;
    local.sin_port=htons(PORT);
    MainSocket=socket(AF_INET,SOCK_STREAM,0);

    if(MainSocket==INVALID_SOCKET)
    {
        return 0;
    }
    if(bind(MainSocket,(struct sockaddr*)&local,sizeof(local))!=0)
    {
        return 0;
    }
    if(listen(MainSocket,10)!=0)
    {
        return 0;
    }


    while(1)
    {
        tmpsock = accept(MainSocket,(struct sockaddr*)&from,&fromlen);
        CreateThread(NULL, NULL, SlaveThread, (LPVOID)tmpsock, NULL, NULL);
    }

}

DWORD WINAPI SlaveThread(LPVOID lparam)
{
    SOCKET ts = (SOCKET)lparam;//temporary socket
......

char data[4096];
                    int n;
                    unsigned long int length = statbuf.st_size;

                    web.SendHeaders(200, "OK", format("Content-Disposition: attachment; filename=\"%s\"", FileName.c_str()).c_str(), web.GetMimeType(ReqPath.c_str()), length, statbuf.st_mtime);
                    unsigned long int i=0,d=0;
                    while ((n = fread(data, 1, sizeof(data), file)) > 0)
                    {
                        d+=send(ts, data, n, 0);
                        i+=n;
                    }
                    printf("%i=%i=%i\n", length,i,d);
                    fclose(file);

Answer 1

Assuming that data is char[] of some size, and that string is std::string your code doesn’t do what you think it does. When you pass data to WEB::Send it’s creating a std::string from all the bytes in data up to the first 0, which probably is about 2% of the total data. You want to call web.Send(std::string(data, n)); instead.

Also in WEB::Send you need to call data.data() instead of c_str() to avoid the same problems with nulls.