[Users] Route-header DNS lookup?

[Norman Brandinger]

Hi Kerker,

Perhaps there needs to be SRV records in the DNS server that manages 
iptel1.ipatl.se.

Below are example SRV records.  If this is your first time working with 
SRV records, I strongly suggest reading some of the online doc that 
deals with them.

_sip._tcp.iptel1.ipatl.se.             IN SRV 0 0 5060 sip.iptel1.ipatl.se.
_sip._udp.iptel1.ipatl.se.             IN SRV 0 0 5060 sip.iptel1.ipatl.se.

Regards,
Norm

Kerker Staffan wrote:
> hi
> i recently bounced into this problem, and i'm not sure here. 
> i'm running the openser-devel, with the cacheless db_mode=3. (works fine btw)
>
> the record-route header received by the proxy on the other side (SNOM4S), inserts
> the domain name (iptel1.ipatl.se) and not the hostname (sip.iptel1.ipatl.se) in the 
> record-route header, and uses the maddr=<ip_of_server> with the actual server IP address.
>
> now, when my client (behind the OpenSER) replies with an ACK to the incomming OK, 
> it uses the Route-header recieved in the RR-header, and sends the ACK to OpenSER. i 
> then get the following errors in OpenSER. 
>
> ---
> /usr/local/sbin/openser[3583]: ERROR: mk_proxy: could not resolve hostname: "iptel1.ipatl.se"
> /usr/local/sbin/openser[3583]: ERROR: uri2proxy: bad host name in URI <sip:4ffec4ce755c218a72228c6643cb3b6b at iptel1.ipatl.se:5060;maddr=172.28.248.66;transport=udp;lr>
> ---
>
> the ACK i sent look like this:
>
> ---
> Request-Line: ACK sip:2307 at iptel1.ipatl.se;gruu=6fg9n6dl SIP/2.0
>       Via: SIP/2.0/UDP 172.28.248.52:2051;branch=z9hG4bK-d96b1fvapkyn;rport
>       Route: <sip:172.28.248.10;lr=on;ftag=li9buf1i4p>
>       Route: <sip:4ffec4ce755c218a72228c6643cb3b6b at iptel1.ipatl.se:5060;maddr=		172.28.248.66;transport=udp;lr>
>       From: "Snom 2652" <sip:2652 at ipatl.se>;tag=li9buf1i4p
>       To: <sip:2307 at ipatl.se>;tag=hvseiz7kgb
>       Call-ID: 3c269d83900b-xj3ild14y880 at snom360
>       CSeq: 1 ACK
>       Max-Forwards: 70
>       Contact: <sip:2652 at 172.28.248.52:2051;line=cp4a7ljd>
>       Content-Length: 0
> ---
>
> as far as i understand, according the rfc 3263, the route-header may contain domain name that
> has to be resolved using SRV.
>
> ---
> "6 Constructing SIP URIs
>
>    In many cases, an element needs to construct a SIP URI for inclusion
>    in a Contact header in a REGISTER, or in a Record-Route header in an
>    INVITE.  According to RFC 3261 [1], these URIs have to have the
>    property that they resolve to the specific element that inserted
>    them.  However, if they are constructed with just an IP address, for
>    example:
>
>    sip:1.2.3.4
>
>    then should the element fail, there is no way to route the request or
>    response through a backup.
>
>    SRV provides a way to fix this.  Instead of using an IP address, a
>    domain name that resolves to an SRV record can be used:
>
>    sip:server23.provider.com"
> ---
>
> now, OpenSER only asks DNS for an A record of the name recieved in the route header,
> and since that's a domain name, it's unresolvable, and so the ACK is never sent. 
>
> any hints or clues? 
>
> best regards,
> /Staffan Kerker
>
>
> --
> Staffan Kerker
> Saab Communications, Växjö
> p. +46 470 42185
> c. +46 705 391365
> m. staffan.kerker at saabgroup.com
>  
>
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