Opting out of Google Instant Browsing

I recently wrote about a new feature of Google Chrome called Instant Browsing. You can turn it on or off Basic tab of the  Options page in Chrome.

If you are a web site owner/administrator and are concerned about the impact it might have on your web server to have a deluge of requests going to your server that the end user is probably not really interested in, or having a number of requests going to your server that result in a 404 resource not found because the half formed URL in the “omnibox” does not actually resolve to a real page then you can opt out.

For folks running ASP.NET (both WebForms and MVC) I’ve created a simple HTTP Module that will opt your site out if it encounters requests from Chromes’ Instant Browsing.

You can download the Module here: Instant Browsing HTTP Module V1. And to activate it in your application you need to add the DLL file as a reference to your application and then add the bolded line to your web.config.

<configuration>
 <system.web>
  <httpModules>
   <add name="InstantBrowsingOptOut" type="InstantBrowsing.InstantBrowsingOptOut, InstantBrowsing"/>
  </httpModules>
 </system.web>
</configuration>

The Code

If you prefer, you can add the following source to your application and compile it yourself.

using System;
using System.Collections.Specialized;
using System.Web;

namespace InstantBrowsing
{
    public class InstantBrowsingOptOut : IHttpModule
    {
        public void Dispose()
        {
            // Nothing to dispose. Required by IHttpModule
        }

        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(BeginRequest);
        }

        void BeginRequest(object sender, EventArgs e)
        {
            HttpApplication application = (HttpApplication)sender;

            string headerValue = GetPurposeHeaderValue(application.Request);
            if (HeaderValueDoesntExist(headerValue))
                return;

            if (PreviewMode(headerValue))
                Issue403Forbidden(application.Response);
        }

        private bool PreviewMode(string value)
        {
            return value.ToLowerInvariant().Contains("preview");
        }

        private bool HeaderValueDoesntExist(string value)
        {
            return string.IsNullOrEmpty(value);
        }

        private string GetPurposeHeaderValue(HttpRequest request)
        {
            NameValueCollection headers = request.Headers;
            return headers["X-Purpose"];
        }

        private void Issue403Forbidden(HttpResponse response)
        {
            response.Clear();
            response.StatusCode = 403;
            response.End();
        }
    }
}

And to activate it in your application you need to add the bolded line to your web.config.

<configuration>
 <system.web>
  <httpModules>
   <add name="InstantBrowsingOptOut" type="InstantBrowsing.InstantBrowsingOptOut, InstantBrowsing"/>
  </httpModules>
 </system.web>
</configuration>

Note that the second “InstantBrowsing” in the type attribute is the assembly, so if you’ve put it in an assembly with a different name you’ll need to change the type attribute to reflect that.