オフラインかどうかの取得/設定

    static BOOL IsGlobalOffline()

    {

        BOOL fRet = FALSE;

        DWORD dwState = 0;

        DWORD dwSize = sizeof(DWORD);

        if (::InternetQueryOption(NULL, INTERNET_OPTION_CONNECTED_STATE, &dwState, &dwSize))

        {

            if(dwState & INTERNET_STATE_DISCONNECTED_BY_USER)

                fRet = TRUE;

        }

        return fRet;

    }

    static void SetGlobalOffline(BOOL bOffline)

    {

        INTERNET_CONNECTED_INFO ci;

        memset(&ci, 0, sizeof(ci));

        if (bOffline)

        {

            ci.dwConnectedState = INTERNET_STATE_DISCONNECTED_BY_USER;

            ci.dwFlags = ISO_FORCE_DISCONNECTED;

        }

        else

        {

            ci.dwConnectedState = INTERNET_STATE_CONNECTED;

        }

        ::InternetSetOption(NULL, INTERNET_OPTION_CONNECTED_STATE, &ci, sizeof(ci));

    }