Error Handling for WebRequest & Response

Question

I am currently running a method that takes a string (a domain name) and checks to see if the site is available or not and passes the information into a Domain object I have created. Currently, I am running into an issue where one of the sites is down and is in turn crashing the application. Below is the method:

private Domain GetStatus(string x)
    {
        string status = "";

        WebRequest req = HttpWebRequest.Create("http://www." + x);
        WebResponse res = req.GetResponse();
        HttpWebResponse response = (HttpWebResponse)res;
        if ((int)response.StatusCode > 226 || response.StatusCode == HttpStatusCode.NotFound)
        {
            status = "ERROR: " + response.StatusCode.ToString();
        }
        else
        {
            status = "LIVE";
        }

        Domain temp = new Domain(x, status);
        return temp;
    }

Initial thoughts were that the response.StatusCode == HttpStatusCode.NotFound would handle such an error but it is currently crashing on the line WebResponse res = req.GetResponse(); with the following response:

System.Net.WebException: 'The remote name could not be resolved: 'www.DOMAIN.com''

Answer 1

The issue is due to the fact that your own code is raising an exception.

This can be due to the lack of an internet connection, or a dns resolve issue (which could be caused by the remote party).

So, if the remote server throws an error, you'll get HTTP 500 Internal Server Error, if you can't reach it; your code throws an exception and you'll need to handle that.

To fix this, you can use a try/catch block, something like this:

private Domain GetStatus(string x)
{
    string status = "";

    try
    {    
         WebRequest req = HttpWebRequest.Create("http://www." + x);
         WebResponse res = req.GetResponse();
         HttpWebResponse response = (HttpWebResponse)res;
         if ((int)response.StatusCode > 226 || 
             response.StatusCode ==  HttpStatusCode.NotFound)
         {
             status = "ERROR: " + response.StatusCode.ToString();
         }
         else
         {
             status = "LIVE";
         }
     }
     catch (Exception e)
     {
          status = "ERROR: Something bad happend: " + e.ToString();
     }

     Domain temp = new Domain(x, status);
     return temp;
}

---

By the way, the message,

The remote name could not be resolved

indicates that the host cannot be resolved.

Most likely cause is that your internet is down or, the domain is misspelled or the route to the domain is faulty (e.g. on intranet environments).