problems with complex import/export attributes

1 Feb 2001

      Hi,

Yes, I know this is not a RPSL forum, but i think someone
of you could help me ;-)

I found a problem for RPSL parsers conform with RFC2622. In the
RFC2622 (section 6.6) is an example of an import attribute:
...
import: from AS1 action pref = 1; accept as-foo;
        except {
           from AS2 action pref = 2; accept AS226;
           except {
              from AS3 action pref = 3; accept {128.9.0.0/16};
           }
        }
Appendix B "Grammar Rules" describes the syntax like below:
...
...
import_attribute: ATTR_IMPORT
| ATTR_IMPORT opt_protocol_from opt_protocol_into import_factor
import_expression: import_term
| import_term KEYW_REFINE import_expression
| import_term KEYW_EXCEPT import_expression
import_term: import_factor ';'
| '{' import_factor_list '}'
import_factor_list: import_factor ';'
| import_factor_list import_factor ';'
import_factor: import_peering_action_list KEYW_ACCEPT filter
import_peering_action_list: KEYW_FROM peering opt_action
| import_peering_action_list KEYW_FROM peering opt_action
...
I feel in import_attribute lakes a line like:

 | ATTR_IMPORT opt_protocol_from opt_protocol_into import_expression

and a look into ftp://ftp.isi.edu/ra/RAToolSet/RAToolSet-4.6.3.tar.gz
file src/rpsl/rpsl/rpsl.y agree with me:
...
...
import_attribute: ATTR_IMPORT
                  opt_protocol_from opt_protocol_into
                  import_expr TKN_EOA {
   $$ = changeCurrentAttr(new AttrImport($2, $3, $4));
}
| ATTR_IMPORT opt_protocol_from opt_protocol_into import_factor TKN_EOA {
   PolicyTerm *term = new PolicyTerm;
   term->append($4);
$$ = changeCurrentAttr(new AttrImport($2, $3, term));
}
| ATTR_IMPORT error TKN_EOA {
   $$ = $1;
   handle_error("Error: from <peering> expected.\n");
   yyerrok;
}
;
..
OK as so far, but rpslcheck as well as my perl parser module breaks
while parsing the example above ;-(
...
fb@sun5 1315> rpslcheck < example 
...
import: from AS1 action pref = 1;
        accept as-foo;
        except {
          from AS2 action pref = 2; accept AS226;
           except {
           ^^^^^^
***Error: from <peering> expected.
            from AS3 action pref = 3; accept {128.9.0.0/16};
          }
       }
...
For me looks the grammar correct, but my knowledge about automata theory,
languages and computation is worser than my english ;-)

Has anybody a solution for this problem ?

cheers
frank

problems with complex import/export attributes

Frank Bohnsack