musl - RE: Queries with less than `ndots` dots never lead to resolution using the global namespace if the `search` domains don't work

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Message-ID: <1e14e4e5bddc41518ff651e4b841c2b1@CHBARSRV1EXCHP1.ANYACCESS.NET>
Date: Wed, 15 Mar 2017 17:10:08 +0000
From: <dominic.chambers@...ncore.com>
To: <musl@...ts.openwall.com>
Subject: RE: Queries with less than `ndots` dots never lead to
 resolution using the global namespace if the `search` domains don't work

HI Rich,

I've attached the results from running the following two commands:

  1. ` strace ./gai3a google.com 2> strace_of_google-com.txt`
  2. ` strace ./gai3a google.com.default.svc 2> strace_of_google-com-default-svc.txt`

Is this what you were looking for or can I provide something more useful?

Thanks again, Dominic.

-----Original Message-----
From: Rich Felker [mailto:dalias@...ifal.cx] On Behalf Of Rich Felker
Sent: 15 March 2017 16:11
To: musl@...ts.openwall.com
Subject: Re: [musl] Queries with less than `ndots` dots never lead to resolution using the global namespace if the `search` domains don't work

On Wed, Mar 15, 2017 at 12:58:02PM +0000, dominic.chambers@...ncore.com wrote:
> HI Rich,
> 
> Thanks for the prompt response here. Apologies for any confusion I may 
> have created, but I think the server is responding with an overall 
> `NXDOMAIN` response. This is what I get from running `dig
> google.com.default.svc.cluster.local`:
> 
> ```
> ; <<>> DiG 9.10.3-P4-Ubuntu <<>> google.com.default.svc.cluster.local
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 20863 ;; flags: 
> qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
> 
> ;; QUESTION SECTION:
> ;google.com.default.svc.cluster.local. IN A
> 
> ;; AUTHORITY SECTION:
> cluster.local.          60      IN      SOA     ns.dns.cluster.local. hostmaster
> .cluster.local. 1489579200 28800 7200 604800 60
> 
> ;; Query time: 0 msec
> ;; SERVER: 10.43.0.10#53(10.43.0.10)
> ;; WHEN: Wed Mar 15 12:49:14 UTC 2017
> ;; MSG SIZE  rcvd: 147
> ```
> 
> Although there's less information with nslookup, the response from 
> running `nslookup google.com.default.svc.cluster.local` seems even 
> more definitive:
> 
> ```
> Server:         10.43.0.10
> Address:        10.43.0.10#53
> 
> ** server can't find google.com.default.svc.cluster.local: NXDOMAIN 
> ```
> 
> Maybe I was just reading too much into the output from dig regarding 
> exactly what was being returned from the server. Any further thoughts?

Can you send an strace log of an affected lookup with musl's resolver (rather than dig/nslookup which use bind's resolver) for me to look at? Attached is source for a trivial sample utility to perform a lookup.

Rich
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View attachment "strace_of_google-com.txt" of type "text/plain" (5095 bytes)

View attachment "strace_of_google-com-default-svc.txt" of type "text/plain" (5081 bytes)

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