[OpenSIPS-Users] Truncated Branch in Via
Bogdan-Andrei Iancu
bogdan at opensips.org
Fri Jul 8 16:30:47 CEST 2016
Hi Rahul,
Indeed, that is a good pointhere, thanks for bring it up. Let me
investigate the code a bit and I will update you.
Regards,
Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com
On 07.07.2016 22:01, Gupta, Rahul wrote:
>
> Hi Bogdan, so the problem we are facing is the endpoint has a new
> branch however the difference in the branch value is *AFTER* the
> MAX_BRANCH_PARAM_LEN, the highlighted text.Since opensips is copying
> the partial branch which is same as the previous Via and thus our SIP
> stack (OCCAS) is sending back 401 Unauthorized for both thinking it’s
> a retransmit.
>
> This is also in line with RFC3261. Shouldn’t it copy the entire Via to
> make sure it’s different from previous Message ?
>
> *REGISTER 1*
>
> Via: SIP/2.0/UDP
> 10.204.70.156:5060;branch=z9hG4bK1c68e33e-848e-412a-9137-4fb065a7b7eb_0efbfc5e_11391
>
> Via: SIP/2.0/UDP
> 10.205.236.44:5060;branch=z9hG4bK1c68e33e-848e-412a-9137-4fb065a7b7eb_0efbfc5e_113915620064228_MTAuMTIuMy4xMQ
>
> *REGISTER 2*
>
> Via: SIP/2.0/UDP
> 10.204.70.156:5060;branch=z9hG4bK1c68e33e-848e-412a-9137-4fb065a7b7eb_0efbfc5e_11391
>
> Via: SIP/2.0/UDP
> 10.205.236.44:5060;branch=z9hG4bK1c68e33e-848e-412a-9137-4fb065a7b7eb_0efbfc5e_113915656050004_MTAuMTIuMy4xMQ
>
> *Thanks*
>
> *Rahul Gupta***
>
> Systems Architect
>
> *T*+1 732-690-3845 |*E* rahul.gupta at ipc.com <mailto:rahul.gupta at ipc.com>
>
> cid:image006.jpg at 01D1940F.3E021840
>
> *From:*Bogdan-Andrei Iancu [mailto:bogdan at opensips.org]
> *Sent:* Thursday, July 07, 2016 4:43 AM
> *To:* Gupta, Rahul
> *Cc:* Elliott, Ray; users at lists.opensips.org
> *Subject:* Re: [OpenSIPS-Users] Truncated Branch in Via
>
> Hi Rahul,
>
> The received VIA hdr (with the .44 IP) is properly preserved when
> forwarding (in the outbound message).
>
> The VIA hdr added by OpenSIPS ( .156 IP) is a completely new VIA and
> its branch value is completely independent from the branch of other
> VIA hdrs.
>
> Why do they look the same ? The RFC3261 says that for stateless fwd
> (when basically there is no transaction, so no branch value), to avoid
> populating its VIA with ";branch=0" , the proxy may "copy" and use a
> branch value from an older VIA (a received VIA) - keep in mind it does
> not say to copy it entirely or part. So, OpenSIPS copies a
> MAX_BRANCH_PARAM_LEN length string from the previous branch param.
>
> Everything is correct and legal (from RFC perspective).
>
> PS: if you would use t_relay() instead of forward() - doing statefull
> proxy -, you will see that the branch in the VIA added by OpenSIPS
> will be completly different from the value in the previous VIA.
>
> Best regards,
>
> Bogdan-Andrei Iancu
> OpenSIPS Founder and Developer
> http://www.opensips-solutions.com
>
> On 07.07.2016 03:42, Gupta, Rahul wrote:
>
> Hi Bogdan,
>
> Here is a Ethernet trace (pcap) file that has a successful and an
> unsuccessful registration.
>
> Frames 1-8 illustrate the successful case with Frames 2 and 6 show
> how opensips adds an extra VIA header that has a full VIA;branch
>
> Frame:2
>
> Via: SIP/2.0/UDP
> 10.204.70.156:5060;branch=z9hG4bK-c45d6-2ff0ce63-4583dc45-6bd144f8
>
> Via: SIP/2.0/UDP
> 10.204.45.122:5060;branch=z9hG4bK-c45d6-2ff0ce63-4583dc45-6bd144f8
>
> Frames 9-16 illustrate the unsuccessful case where Frames 10 and
> 14 show how opensips adds an extra VIA header that has a truncated
> branch.
>
> Frame 10:
>
> Via: SIP/2.0/UDP
> 10.204.70.156:5060;branch=z9hG4bK1c68e33e-848e-412a-9137-4fb065a7b7eb_0efbfc5e_11391
>
> Via: SIP/2.0/UDP
> 10.205.236.44:5060;branch=z9hG4bK1c68e33e-848e-412a-9137-4fb065a7b7eb_0efbfc5e_113915620064228_MTAuMTIuMy4xMQ
>
> *Thanks*
>
> *Rahul Gupta*
>
> Systems Architect
>
> *T*+1 732-690-3845 |*E* rahul.gupta at ipc.com
> <mailto:rahul.gupta at ipc.com>
>
> cid:image006.jpg at 01D1940F.3E021840
>
> *From:*Bogdan-Andrei Iancu [mailto:bogdan at opensips.org]
> *Sent:* Wednesday, July 06, 2016 5:38 AM
> *To:* OpenSIPS users mailling list
> *Cc:* Elliott, Ray; Gupta, Rahul
> *Subject:* Re: [OpenSIPS-Users] Truncated Branch in Via
>
> Hi Rahul,
>
> That define is used to calculate the the max VIA len when OpenSIPS
> is generating its own VIA headers. That max len does not impact
> the VIA headers which were received.
>
> I do not understand exactly (in your example) what's the flow of
> that VIA header. If you want, send me off-list the pcap/ngrep
> showing the SIP package (before and after OpenSIPS) and how it is
> affected.
>
> Regards,
>
>
> Bogdan-Andrei Iancu
>
> OpenSIPS Founder and Developer
>
> http://www.opensips-solutions.com
>
> On 05.07.2016 20:57, Gupta, Rahul wrote:
>
> We are using opensips 1.11.5 as a stateless proxy and seeing a
> truncated Branch in Via for my REGISTER message. After some
> code digging, the MAX length is calculated using the following
> formula and seems like its truncating the branch after 55
> characters. This is causing the REGISTER to fail in our case.
> Is there a config level solution to this ?
>
> *#define MAX_BRANCH_PARAM_LEN (MCOOKIE_LEN+8 /*!<int2hex*/ +
> 1 /*sep*/ + \*
>
> *MD5_LEN + 1 /*!<sep*/ + 8 /*int2hex*/ + \*
>
> *1 /*extra space, needed by t_calc_branch*/)*
>
> truncated from opensips àVia: SIP/2.0/UDP
> XX.XX.XX.XX:5060;branch=z9hG4bK0fddbbc9-1487-4755-a0b3-0c319155b8c3_0efbfc5e_11160
>
>
> Via from EndPoint àVia: SIP/2.0/UDP
> XX.XX.XX.XX:5060;branch=z9hG4bK0fddbbc9-1487-4755-a0b3-0c319155b8c3_0efbfc5e_1116078308924346_MTAuMTIuMy4xMQ
>
>
> *Thanks*
>
> *Rahul Gupta*
>
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