Re: Problem with NetBSd 5.1.2 / gethostbyname / nsswitch.conf or bind resolving chain of multiple cnames

[thilo <thilo%nispuk.com@localhost>]

On 9/9/2012 5:43 PM, matthew sporleder wrote:
> On Sun, Sep 9, 2012 at 11:25 AM, matthew sporleder 
> <msporleder%gmail.com@localhost> wrote:
>> On Sun, Sep 9, 2012 at 5:43 AM, thilo <thilo%nispuk.com@localhost> wrote:
>>> Hello everyone,
>>>
>>> I have an issue with my name resolving and I am not sure where the
>>> problem lies:
>>>
>>> On my server I can resolve an address with multiple cnames via nslookup
>>> to my local bind server.
>>> The clibrary gethostbyname fails the lookup if the cname chain is
>>> greater than 2.
>>> I cannot seem to find anywhere a switch/define that would limit the
>>> number of recursive lookups.
>>>
>>> Changing the order in /etc/nsswitch.conf from "files dns" -> "dns
>>> file" changes the herror output from
>>> "Unknown server error" -> "Unknown host".
>>> Interesting enough windows and linux clients in my network do not have
>>> this problem, but another netbsd box does too.
>>>
>>> Does someone know what is wrong in my configuration?
>>> Thanks for the help
>>> thilo
>>>
>>>
>>> == log from various tools ==
>>> -bash-4.2$ nslookup dradio_mp3_dkultur_m.akacast.akamaistream.net
>>> Server: 127.0.0.1
>>> Address: 127.0.0.1#53
>>>
>>> Non-authoritative answer:
>>> dradio_mp3_dkultur_m.akacast.akamaistream.net canonical name =
>>> out.icecast.akadns.net.
>>> out.icecast.akadns.net canonical name = eu.ic.akadns.net.
>>> eu.ic.akadns.net canonical name = edge13647.icecast.akadns.net.
>>> Name: edge13647.icecast.akadns.net
>>> Address: 195.27.154.158
>>>
>>> ====== PING FIRST HOST==================================
>>> -bash-4.2$ ping -c 1 dradio_mp3_dkultur_m.akacast.akamaistream.net
>>> ping: Cannot resolve "dradio_mp3_dkultur_m.akacast.akamaistream.net"
>>> (Unknown host)
>>> ====== PING SECOND HOST==================================
>>> -bash-4.2$ ping -c 1 out.icecast.akadns.net
>>> PING edge14152.icecast.akadns.net (195.10.36.180): 56 data bytes
>>> 64 bytes from 195.10.36.180: icmp_seq=0 ttl=59 time=63.583 ms
>>>
>>> ----edge14152.icecast.akadns.net PING Statistics----
>>> 1 packets transmitted, 1 packets received, 0.0% packet loss
>>> round-trip min/avg/max/stddev = 63.583/63.583/63.583/0.000 ms
>>> =========UNAME=======================================
>>> -bash-4.2$ uname -a
>>> NetBSD maggi 5.1.2 NetBSD 5.1.2 (GENERIC) #0: Thu Feb 2 12:12:28 UTC
>>> 2012
>>>
builds%b7.netbsd.org@localhost:/home/builds/ab/netbsd-5-1-2-RELEASE/amd64/201202021012Z-obj/home/builds/ab/netbsd-5-1-2-RELEASE/src/sys/arch/amd64/compile/GENERIC
>>> amd64
>>>
>>> ============= NAMED versions =============
>>> I tried bind 9.7.3 and 9.9.1 :
>>> -bash-4.2$ /usr/sbin/named -v
>>> BIND 9.7.3-P3
>>> -bash-4.2$ /usr/pkg/sbin/named -v
>>> BIND 9.9.1-P2
>>> -bash-4.2$
>>>
>>> ================================
>>
>>
>> This is true on my box too.
>>
>> getent hosts dradio_mp3_dkultur_m.akacast.akamaistream.net
>
> This is an issue with netbsd resolving hosts with _ (underscore) in
the name.
I understand, after some more reading, that rfc 952 specifies
"letter-or-digit-or-hyphen" inside of a hostname.
But linux and windows do not seem to complain and resolve ok.

For my application it would be nice if I don't have to resolve to
strange hoops in order to lookup a name that fails the test in res_hnok().
Since the resolver already uses an environment variable "RES_OPTIONS"
according to the man page, would it be acceptable for NetBSD to have a
"linux compatibility and violate rfc" flag?

Or is such strict checking really required?

cheers thilo



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