IDN, dig and underscore

[Mark Andrews]

> I've upgraded to bind 9.4.0rc1 form 9.4.0b4 and I've discovered they both hav
> e 
> some odd behaviour when I enable IDN.
> 
> If I do:
> $ dig _ldap._tcp.example.com
> dig: convert UTF-8 textname to IDN encoding: prohibited character found
> 
> Removing the underscores makes it not complain. I assumed the problem was wit
> h 
> idnkit, but when I tested this:
> $ echo _ldap._tcp.example.com | idnconv
> _ldap._tcp.example.com
> 
> idnkit seems happy to pass the underscores through. It also handles:
> $ echo _ldap._tcp.démonstration.com | idnconv
> _ldap._tcp.xn--dmonstration-beb.com
> 
> So, idnkit is willing to deal with names with _, but dig is not. If I disable
>  
> IDN (either by using the IDN_DISABLE environment variable or recompiling), I 
> can do:
> $ dig _ldap._tcp.example.com
> with no problem.
> 
> Are IDN and _ names mutually exclusive? Thanks.
> -- 
> --Andre Masella (andre at masella.no-ip.org)

	By default idnconv only converts and checks labels containing
	non-ascii characters.  You need to add -w to simulate what
	dig is doing.

	Mark

drugs:bind9 12:19 {649} % echo _ldap._tcp.xn--dmonstration-beb.com | idnconv -out UTF-8 -r | idnconv -i UTF-8 -w -A
_ldap._tcp.xn--dmonstration-beb.com
drugs:bind9 12:20 {650} % echo _ldap._tcp.xn--dmonstration-beb.com | idnconv -out UTF-8 -r | idnconv -i UTF-8 -w 
error in nameprep or output conversion at line 1: prohibited character found
drugs:bind9 12:20 {651} % 

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