Test if a URI is up

Question

I'm trying to make a simple app that will "ping" a uri and tell me if its responding or not

I have the following code but it only seems to check domains at the root level

ie www.google.com and not www.google.com/voice

private bool WebsiteUp(string path)
    {

        bool status = false;

        try
        {
            Uri uri = new Uri(path);
            WebRequest request = WebRequest.Create(uri);
            request.Timeout = 3000;
            WebResponse response;
            response = request.GetResponse();
            if (response.Headers != null) 
            {
                status = true;
            }

        }
        catch (Exception loi) 
        {
            return false;
        }


        return status;
    }

Is there any existing code out there that would better fit this need?

Answer 1

There is a Ping class you can utilize for that, more details can be found here: http://msdn.microsoft.com/en-us/library/system.net.networkinformation.ping.aspx

Answer 2

I did something similar when I wrote a torrent client to check valid tracker URLS, pretty sure I found the answer on SO but cant seem to find it anymore, heres the code sample I have from that post.

   using(var client = new WebClient()) { 
        client.HeadOnly = true; 
        // exists
        string Address1 = client.DownloadString("http://google.com"); 
        // doesnt exist - 404 error
        string Address2 = client.DownloadString("http://google.com/sdfsddsf"); 
    } 

Answer 3

Edit: Actually, I tell a lie - by default 404 should cause a web exception anyway, and I've just confirmed this in case I was misremembering. While the code given in the example is leaky, it should still work. Puzzling, but I'll leave this answer here for the better safety with the response object.

---

The problem with the code you have, is that while it is indeed checking the precise URI given, it considers 404, 500, 200 etc. as equally "successful". It also is a bit wasteful in using GET to do a job HEAD suffices for. It should really clean up that WebResponse too. And the term path is a silly parameter name for something that isn't just a path, while we're at it.

private bool WebsiteUp(string uri)
{
    try
    {
        WebRequest request = WebRequest.Create(uri);
        request.Timeout = 3000;
        request.Method = "HEAD";
        using(WebResponse response = request.GetResponse())
        {
            HttpWebResponse hRes = response as HttpWebResponse;
            if(hRes == null)
                throw new ArgumentException("Not an HTTP or HTTPS request"); // you may want to have this specifically handle e.g. FTP, but I'm just throwing an exception for now.
            return hRes.StatusCode / 100 == 2;
        }
    }
    catch (WebException) 
    {
        return false;
    }
}

Of course there are poor websites out there that return a 200 all the time and so on, but this is the best one can do. It assumes that in the case of a redirect you care about the ultimate target of the redirect (do you finally end up on a successful page or an error page), but if you care about the specific URI you could turn off automatic redirect following, and consider 3xx codes successful too.