Request Web Page in c# spoofing the Host

Question

I need to create a request for a web page delivered to our web sites, but I need to be able to set the host header information too. I have tried this using HttpWebRequest, but the Header information is read only (Or at least the Host part of it is). I need to do this because we want to perform the initial request for a page before the user can. We have 10 web server which are load balanced, so we need to request the file from each of the web servers.

I have tried the following:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://192.168.1.5/filename.htm");
request.Headers.Set("Host", "www.mywebsite.com");
WebResponse response = request.GetResponse();

Obviously this does not work, as I can't update the header, and I don't know if this is indeed the right way to do it.

Answer 1

I know this is old, but I came across this same exact problem, and I found a better solution to this then using sockets or reflection...

What I did was create a new class that durives from WebHeaderCollection and bypasses validation of what you stick inside it:

public class MyHeaderCollection:WebHeaderCollection
{
    public new void Set(string name, string value)
    {
        AddWithoutValidate(name, value);
    }
    //or
    public new string this[string name]
    {
        get { return base[name]; }
        set { AddWithoutValidate(name, value); }
    }
}

and here is how you use it:

    var http = WebRequest.Create("http://example.com/");
    var headers = new MyHeaderCollection();
    http.Headers = headers;

    //Now you can add/override anything you like without validation:
    headers.Set("Host", http.RequestUri.Host);
    //or
    headers["Host"] = http.RequestUri.Host;

Hope this helps anyone looking for this!