title: how to get URL from HttpExchange?
body: <p>I have this custom HTTP server but I want to be able to serve different content based on the different URLs.</p>
  
  <p>How do I get the full URL from HttpExchange?</p>
  
  <p>Example:</p>
  
  <p>www.abcdefg.com/index.html will serve content for abcdefg</p>
  
  <p>www.qrstuvwxyz.com/index.html will serve content for qrstuvwxyz</p>
  
  <p>similarly, rawrrawr.abcdefg.com/index.html will serve content for abcdefg under the section rawrrawr.</p>
  
  <p>or en.abcdefg.com serve english, cn.abcdefg.com serve chinese, fr.abcdefg.com serve french etc etc etc.</p>