How to convert a Net::HTTP response to a certain encoding in Ruby 1.9.1?

I have a Sinatra application (http://analyzethis.espace-technologies.com) that does the following

1. Retrieve an HTML page (via net/http)
2. Create a Nokogiri document from the response.body
3. Extract some info and send it back in the response. The response should be UTF-8 encoded

So I came to the problem while trying to read sites that use windows-1256 encodings like www.filfan.com or www.masrawy.com.

The problem is the result of the encoding conversion is not correct though no errors are thrown.

The net/http response.body.encoding gives ASCII-8BIT which can not be converted to UTF-8

If I do Nokogiri::HTML(response.body) and use the css selectors to get certain content from the page - say the content of the title tag for example - I get a string which when i call string.encoding returns WINDOWS-1256. I use string.encode("utf-8") and send the response using that but again the response is not correct.

Any suggestions or ideas about what's wrong in my approach?