code: private static HttpHost determineTarget(HttpUriRequest request) throws ClientProtocolException {
  		// A null target may be acceptable if there is a default target.
  		// Otherwise, the null target is detected in the director.
  		HttpHost target = null;
  		URI requestURI = request.getURI();
  		if (requestURI.isAbsolute()) {
  			target = URIUtils.extractHost(requestURI);
  			if (target == null) {
  				throw new ClientProtocolException(
  						"URI does not specify a valid host name: " + requestURI);
  			}
  		}
  		return target;
  	}
docs: copied from httpclient source code