def check_feed_authorization
    if request.env.has_key? 'X-HTTP_AUTHORIZATION'
      # try to get it where mod_rewrite might have put it
      authdata = @request.env['X-HTTP_AUTHORIZATION'].to_s.split
    elsif request.env.has_key? 'HTTP_AUTHORIZATION'
      # this is the regular location
      authdata = @request.env['HTTP_AUTHORIZATION'].to_s.split
    end

    # at the moment we only support basic authentication
    @allowed_user=nil
    if authdata and authdata[0] == 'Basic'
      email,password=Base64.decode64(authdata[1]).split(':')[0..1]
      @allowed_user = User.authenticate(email,password)
    end

    if @allowed_user
      return @allowed_user
    else
      #deny_access
      return nil
    end
  end

  def deny_access
    @response.headers["WWW-Authenticate"] = "Basic realm=\"listasgems\""
      render :nothing=>true, :status=>401
  end