Regexp issue in NAPTR rewrite

[Mark Andrews]

In message <4A093B9C.5060100 at afnic.fr>, sandoche BALAKRICHENAN writes:
> 
> I want to rewrite a query of the form 
> "sgtin.5.4.0.0.0.1.3.2.4.5.6.7.6.id.onsam.test" to 
> "sgtin.5.4.0.0.0.1.3.2.4.5.6.7.6.id.onseu.test" using NAPTR rewrite.
> 
> The NAPTR RR in the zone config is as follows:
> 
> sgtin.5.4.0.0.0.1.3.2.4.5.6.7.6.id.onsam.test        IN     NAPTR    
> 0    0    "r"    ""      "!^sgtin\.([0-9])$!\1.id.onseu.test!"    .
> 
> BIND does not  accept backref "\1" . It shows a syntax error.
> 
> Is the above regexp correct?

You failed to properly escape the string.

>From RFC2168.

   Recall that the regular expression used \2 to extract a domain name
   from the CID, and \. for matching the literal '.' characters
   seperating the domain name components. Since '\' is the escape
   character, literal occurances of a backslash must be escaped by
   another backslash. For the case of the cid.urn.net record above, the
   regular expression entered into the zone file should be
   "/urn:cid:.+@([^\\.]+\\.)(.*)$/\\2/i".  When the client code actually
   receives the record, the pattern will have been converted to
   "/urn:cid:.+@([^.]+\.)(.*)$/\2/i".

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org