asterisk users - Aug 2005 - SRV implementation supporting priority

Does anyone know when Asterisk is supposed to support prioritization of
the SRV records returned. I think it's accepted that right now the
Asterisk always just uses the first record returned regardless of
priority.

I also noticed, on register, that it queries for an A record first. If
it gets a response, it will use that address to send the REGISTER. If it
does not, then it will launch an SRV query and use it. If SRV is
enabled, it should try to use that first. For example, the A record for
acmemanufacturing.com may point to their web server and they wish to use
the same domain for their sip services (ie.
joeuser@acmemanufacturing.com).  If they try to register
joeuser@acmemanufacturing.com to their SIP provider, the asterisk will
resolve the web server via A record and send the request there.

Using 1.0.9

Michael Lunsford wrote:
> Does anyone know when Asterisk is supposed to support prioritization of
> the SRV records returned. I think it's accepted that right now the
> Asterisk always just uses the first record returned regardless of
> priority.
I wonder if this is fixed in CVS-HEAD?  I guess I could check the changelog.

-- 
Eric Wieling * BTEL Consulting * 504-210-3699 x2120

At 9:49 AM -0400 on 8/10/05, Michael Lunsford wrote:
>Does anyone know when Asterisk is supposed to support prioritization of
>the SRV records returned. I think it's accepted that right now the
>Asterisk always just uses the first record returned regardless of
>priority.
>
>I also noticed, on register, that it queries for an A record first. If
>it gets a response, it will use that address to send the REGISTER. If it
>does not, then it will launch an SRV query and use it. If SRV is
>enabled, it should try to use that first. For example, the A record for
>acmemanufacturing.com may point to their web server and they wish to use
>the same domain for their sip services (ie.
>joeuser@acmemanufacturing.com).  If they try to register
>joeuser@acmemanufacturing.com to their SIP provider, the asterisk will
>resolve the web server via A record and send the request there.
>
>Using 1.0.9
Sounds like you've volunteered yourself to make a patch for multi-weight SRV
lookup.  :-)

On your other comment: Recent CVS-HEAD code does NOT exhibit the characteristics
you describe for SRV vs. A record lookup - it seems to work in an expected and
standards compliant way (well, at least for the first SRV record.)  I just
tested it with a single "register" request, and here is the tethereal
output after launch of Asterisk:

  0.000000 my.domain.com -> ns.domain.com DNS Standard query SRV
_sip._udp.example.com
  0.203041 ns.domain.com -> my.domain.com DNS Standard query response SRV 0 0
5060 cookies.example.com
  0.203572 my.domain.com -> ns.domain.com DNS Standard query A
cookies.example.com
  0.305008 my.domain.com -> ns.domain.com DNS Standard query response A
213.21.191.70

This domain (in my test environment) has an A record associated with the
"example.com" record which is different than the A record associated
with cookies.example.com.

*CLI> show version
Asterisk CVS-HEAD built by root@hello.domain.com on a i386 running OpenBSD on
2005-08-05 16:42:52 UTC


JT

I would love to volunteer myself for the patch ... oh, if I could only
write C :-) 

I will be more than happy to contribute to the discussions and design as
well as provide testing for it.

Regarding the A record lookup, I have upgraded to the latest dev and am
seeing that the Asterisk does perform an SRV query first.

Thanks,
Michael

> -----Original Message-----
> From: asterisk-users-bounces@lists.digium.com [mailto:asterisk-users-
> bounces@lists.digium.com] On Behalf Of John Todd
> Sent: Wednesday, August 10, 2005 12:53 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] SRV implementation supporting priority
> 
> At 9:49 AM -0400 on 8/10/05, Michael Lunsford wrote:
> >Does anyone know when Asterisk is supposed to support prioritization
of
> >the SRV records returned. I think it's accepted that right now the
> >Asterisk always just uses the first record returned regardless of
> >priority.
> >
> >I also noticed, on register, that it queries for an A record first.
If
> >it gets a response, it will use that address to send the REGISTER. If
it
> >does not, then it will launch an SRV query and use it. If SRV is
> >enabled, it should try to use that first. For example, the A record
for
> >acmemanufacturing.com may point to their web server and they wish to
use
> >the same domain for their sip services (ie.
> >joeuser@acmemanufacturing.com).  If they try to register
> >joeuser@acmemanufacturing.com to their SIP provider, the asterisk
will
> >resolve the web server via A record and send the request there.
> >
> >Using 1.0.9
> 
> Sounds like you've volunteered yourself to make a patch for
multi-weight
> SRV lookup.  :-)
> 
> On your other comment: Recent CVS-HEAD code does NOT exhibit the
> characteristics you describe for SRV vs. A record lookup - it seems to
> work in an expected and standards compliant way (well, at least for
the
> first SRV record.)  I just tested it with a single "register"
request,
and
> here is the tethereal output after launch of Asterisk:
> 
>   0.000000 my.domain.com -> ns.domain.com DNS Standard query SRV
> _sip._udp.example.com
>   0.203041 ns.domain.com -> my.domain.com DNS Standard query response
SRV
> 0 0 5060 cookies.example.com
>   0.203572 my.domain.com -> ns.domain.com DNS Standard query A
> cookies.example.com
>   0.305008 my.domain.com -> ns.domain.com DNS Standard query response
A
> 213.21.191.70
> 
> This domain (in my test environment) has an A record associated with
the
> "example.com" record which is different than the A record
associated
with
> cookies.example.com.
> 
> *CLI> show version
> Asterisk CVS-HEAD built by root@hello.domain.com on a i386 running
OpenBSD
> on 2005-08-05 16:42:52 UTC
> 
> 
> JT
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