Tuesday, August 30, 2005

Happy 10-year Birthday, Opera!

There are lots of people in the world do not know opera web browser, and may never consider using an IE alternative. But for me, opera has been my browser of choice for 7 years.

The first version of opera I used is 3.x. At that time, IE 4 started to take over the browser market and lots of people were very disappointed about the sluggish Netscape 4. I found opera from Gao Chunhui's personal webstite, and became an fan since then.

The best way to describe opera is: fastest and most innovative web browser. On the office website, they also claim opera has better security track record than others, but I wish they did not say that. Maybe opera's security history looks great on paper, but I believe opera's underdog image helps a lot. I still experience a few crashes with the latest 8.0.2 version, maybe the bugs are hard to be exploited, but they mean something. Firefox once bragged about its security, but you know...

Now lots of people switched to firefox for better user experience (like tabed browsing, easy font size controlling etc), and I know why: it has opera features! And actually it makes me a little bit uncomfortable for firefox not acknowledging its competitor for those features.

Well, there are still lots of things for opera to improve (a few of them are even showstoppers for some people), I am happy with the way opera is. Happy birthday, Opera!

Thursday, August 25, 2005

Why IIS is more secure since 6.0?

If you read Michael Howard's blog, you may remember his article titled"IIS6 vs Apache2 Security Defects". Base on third party's data, IIS 6 shows a better security track record than Apache 2.

So, why IIS 6 becomes much safer? Especially given the notorious security history of IIS 5?

In his new book 19 Deadly Sins of Software Security, Michael Howard tells an interesting story:

(Page 3)"Internet information Server(IIS) 6.0 web server switched entirly to a C++ string class for handling input, and one brave developer claimed he'd amputate his little finger if any buffer overruns were found in his code. As of this writing, the developer still has his finger and no security bulletins have been issued against the web server in the nearly two years since its release."

Monday, August 22, 2005

Using ACE_SPIPE_Acceptor with ACE_Reactor

Using ACE_SPIPE_Acceptor with ACE_Reactor is not very straightforward. There are three things to be noticed:
1. Use ACE_WFMO_Reactor. ACE_Select_Reactor does not work with windows named pipe. Named pipe handle is not socket, so you can not use select() on it. ACE_WFMO_Reactor works because it uses WaitForMultipleObjects().
2. ACE_SPIPE_Acceptor should be registered with the ACE_Reactor::register_handler (ACE_Event_Handler *, ACE_HANDLE) method, since the handle to demultiplex on is an event handle.
3. handle_signal() will be called instead of handle_input() and handle_output(). WaitForMultipleObjects() can not tell whether read or write condition is happening, so ACE_WFMO_Reactor has to can WSAEventSelect() again to check, which means handle_input()/handle_output() only happens for sockets.

As you can see even if they work together, it is not exactly the same "Reactor" model we used to program sockets (no handle_input and handle_output). Proactor model works better with windows named pipe.

Here is an example:

class ClientAcceptor : public ACE_Event_Handler
    ClientAcceptor(ACE_Reactor& reactor)
    int open (const ACE_SPIPE_Addr &listen_addr);
    int handle_signal(int signum, siginfo_t* = 0, ucontext_t* = 0);
    ACE_SPIPE_Acceptor acceptor_;

int ClientAcceptor::open (const ACE_SPIPE_Addr &listen_addr)
    if (this->acceptor_.open (listen_addr, 1) == -1)
        ACE_TEXT ("acceptor.open")),
    //register the event handle
    if( this->reactor()->register_handler(this, this->acceptor_.get_handle()) <
        ACE_TEXT ("register_handler")),
    ACE_DEBUG((LM_DEBUG, ACE_TEXT("ClientAcceptor::open\n")));
    return 0;

int ClientAcceptor::handle_signal(int signum, siginfo_t*, ucontext_t*)
    ACE_DEBUG((LM_DEBUG, ACE_TEXT("ClientAcceptor::handle_signal\n")));
    ACE_SPIPE_Stream stm;
    if (this->acceptor_.accept (stm) == -1)
        ACE_TEXT ("(%P|%t) %p\n"),
        ACE_TEXT ("Failed to accept ")
        ACE_TEXT ("client connection")),
    //If you have only one client to deal with, now you can simply play with
    //To handle multiple clients at the same time, you can either:
    //a. create a new thread for every connection
    //b. use asynchronous IO (shift to Proactor model)
    return 0;

int ACE_TMAIN(int argc, ACE_TCHAR*argv[])
    ACE_WFMO_Reactor wfmo_reactor;
    ACE_Reactor reactor (&wfmo_reactor);
    ACE_SPIPE_Addr addr("mynamedpipe");
    ClientAcceptor acceptor(reactor);
    if (acceptor.open(addr) == -1)
        ACE_ERROR_RETURN((LM_ERROR, ACE_TEXT("Can not open to listen:
        %m\n")), -1);
    //Run event loop
    ACE_DEBUG((LM_NOTICE, ACE_TEXT("Server started\n")));
    return 0;