Hi Bogdan, I'm a bit confused.
>From RFC 3261 states in Section 16.11 Stateless Proxy The requirement for unique branch IDs across space and time applies to stateless proxies as well. However, a stateless proxy cannot simply use a random number generator to compute the first component of the branch ID, as described in Section 16.6 bullet 8. This is because retransmissions of a request need to have the same value, and a stateless proxy cannot tell a retransmission from the original request. Therefore, the component of the branch parameter that makes it unique MUST be the same each time a retransmitted request is forwarded. Thus for a stateless proxy, the branch parameter MUST be computed as a combinatoric function of message parameters which are invariant on retransmission. We are using the stateless implementation of opensips. As such we MUST not use the statefull t_replay() function. Copying the TOP most Via header branch will meet the requirement since that branch value MUST also be "unique branch IDs across space and time." However, just copying apart of that destroys the "unique branch IDs across space and time " requirement. I'm confused because I can not find the requirement that you specified below in RFC 3261. Thanks for your response. Ray Ray Elliott Principal Scientist 777, Commerce Dr., Fairfield, CT 06825 T +1 203 339 7052 M +1 203 848 4550 E [email protected]<mailto:[email protected]> Follow us on twitter: @ipc_Systems_Inc www.ipc.com<http://www.ipc.com/> [cid:[email protected]] From: Bogdan-Andrei Iancu [mailto:[email protected]] Sent: Thursday, July 07, 2016 4:43 AM To: Gupta, Rahul Cc: Elliott, Ray; [email protected] 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 [email protected]<mailto:[email protected]> [cid:[email protected]] From: Bogdan-Andrei Iancu [mailto:[email protected]] 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 --> Via: SIP/2.0/UDP XX.XX.XX.XX:5060;branch=z9hG4bK0fddbbc9-1487-4755-a0b3-0c319155b8c3_0efbfc5e_11160 Via from EndPoint --> Via: SIP/2.0/UDP XX.XX.XX.XX:5060;branch=z9hG4bK0fddbbc9-1487-4755-a0b3-0c319155b8c3_0efbfc5e_1116078308924346_MTAuMTIuMy4xMQ Thanks Rahul Gupta DISCLAIMER: This e-mail may contain information that is confidential, privileged or otherwise protected from disclosure. If you are not an intended recipient of this e-mail, do not duplicate or redistribute it by any means. Please delete it and any attachments and notify the sender that you have received it in error. Unintended recipients are prohibited from taking action on the basis of information in this e-mail. 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