remove verbose error from library, bubble consistent exceptions to the module instead

Author: busterb

lib/msf/core/exploit/dns/server.rb

@@ -123,27 +123,12 @@ def start_service
       self.service.send_response_proc = Proc.new do |cli, data|
         on_send_response(cli,data)
       end
-      
+
       add_static_hosts
       self.service.start(!datastore['DISABLE_NS_CACHE'])
 
     rescue ::Errno::EACCES => e
-      if (srvport.to_i < 1024)
-        print_line(" ")
-        print_error("Could not start the DNS server: #{e}.")
-        print_error(
-          "This module is configured to use a privileged port (#{srvport}). " +
-          "On Unix systems, only the root user account is allowed to bind to privileged ports." +
-          "Please run the framework as root to use this module."
-        )
-        print_error(
-          "On Microsoft Windows systems, this error is returned when a process attempts to "+
-          "listen on a host/port combination that is already in use. For example, Windows XP "+
-          "will return this error if a process attempts to bind() over the system SMB/NetBIOS services."
-        )
-        print_line(" ")
-      end
-      raise e
+      raise Rex::BindFailed.new(e.message)
     end
   end