C# Invalid Server Certificate Handling

Turns out, if you just want to disable certificate validation altogether, you can change the ServerCertificateValidationCallback on the ServicePointManager, like so:

ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

This will validate all certificates (including invalid, expired or self-signed ones).

It would be nice if there were some way of turning off "throw on non-success code" but if you catch WebException you can at least use the response:

using System;
using System.IO;
using System.Web;
using System.Net;

public class Test
{
    static void Main()
    {
        WebRequest request = WebRequest.Create("http://csharpindepth.com/asd");
        try
        {
            using (WebResponse response = request.GetResponse())
            {
                Console.WriteLine("Won't get here");
            }
        }
        catch (WebException e)
        {
            using (WebResponse response = e.Response)
            {
                HttpWebResponse httpResponse = (HttpWebResponse) response;
                Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
                using (Stream data = response.GetResponseStream())
                using (var reader = new StreamReader(data))
                {
                    string text = reader.ReadToEnd();
                    Console.WriteLine(text);
                }
            }
        }
    }
}

You might like to encapsulate the "get me a response even if it's not a success code" bit in a separate method. (I'd suggest you still throw if there isn't a response, e.g. if you couldn't connect.)

If the error response may be large (which is unusual) you may want to tweak HttpWebRequest.DefaultMaximumErrorResponseLength to make sure you get the whole error.