SV: [Users] Route-header DNS lookup?

Kerker Staffan staffan.kerker at saabgroup.com
Fri Jul 7 08:02:12 CEST 2006


hello once more... 

since the record-route-header contains a maddr=<ip_of_server>, shouldn't OpenSER
use that address directly? 

from rfc3261, section 4.

-- 
    The procedures here are invoked when a client needs to send a request
    to a resource identified by a SIP or SIPS (secure SIP) URI.  This URI
    can identify the desired resource to which the request is targeted
    (in which case, the URI is found in the Request-URI), or it can
    identify an intermediate hop towards that resource (in which case,
    the URI is found in the Route header).
    ...
    We define TARGET as the value of the maddr parameter of the URI, if
    present, otherwise, the host value of the hostport component of the
    URI.  It identifies the domain to be contacted.
--

or am i doing something wrong here?

best regards,
/Staffan



>  -----Ursprungligt meddelande-----
>  Från: users-bounces at openser.org 
>  [mailto:users-bounces at openser.org] För Norman Brandinger
>  Skickat: den 6 juli 2006 14:57
>  Till: users at openser.org
>  Ämne: Re: [Users] Route-header DNS lookup?
>  
>  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;ma
>  ddr=172.2
>  > 8.248.66;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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