c# - asp.net mvc: How to redirect a non www to www and vice versa

Question

I would like to redirect all www traffic to non-www traffic

i have copied this into my web.config

<system.webServer> / <rewrite> / <rules> 

<rule name="Remove WWW prefix" > 
<match url="(.*)" ignoreCase="true" /> 
<conditions> 
<add input="{HTTP_HOST}" pattern="^www.domain.com" /> 
</conditions> 
<action type="Redirect" url="http://domain.com/{R:1}" 
    redirectType="Permanent" /> 
</rule> 

per this post

How to redirect with "www" URL's to without "www" URL's or vice-versa?

but I got a 500 internal server error.

Answer 1

You might consider a different approach:

protected void Application_BeginRequest (object sender, EventArgs e)
{
   if (!Request.Url.Host.StartsWith ("www") && !Request.Url.IsLoopback)
   {
      UriBuilder builder = new UriBuilder (Request.Url);
      builder.Host = "www." + Request.Url.Host;
      Response.Redirect (builder.ToString (), true);
   }
}

This will however do a 302 redirect so a little tweak is recommended:

protected void Application_BeginRequest (object sender, EventArgs e)
{
   if (!Request.Url.Host.StartsWith ("www") && !Request.Url.IsLoopback)
   {
      UriBuilder builder = new UriBuilder (Request.Url);
      builder.Host = "www." + Request.Url.Host;
      Response.StatusCode = 301;
      Response.AddHeader ("Location", builder.ToString ());
      Response.End ();
   }
}

This one will return 301 Moved Permanently.