Hi,
I tried to remove a Via header line with:
remove_hf("Via");
Original I have this 2 lines:
Via: SIP/2.0/TCP xxx.xxx.xxx.xxx;branch=z9hG4bK370b.21720bb33c4f8264fde4e7994d288a57.0;i Via: SIP/2.0/TCP yyy.yyy.yyy.yyy:53967;received=yyy.yyy.yyy.yyy;rport=53967;branch=z9hG4bKPjxb0bdb2c9624076815f12937cc9e51d;alias
If I insert remove_hf("Via"); in the cfg, I get:
Via: SIP/2.0/TCP xxx.xxx.xxx.xxx;branch=z9hG4bK370b.21720bb33c4f8264fde4e7994d288a57.0;i ;received=yyy.yyy.yyy.yyy;rport=53967;branch=z9hG4bKPjxb0bdb2c9624076815f12937cc9e51d;alias
Doesn't mattter if the command make sense or not, the result, in my opinion, is wrong. The INVITE packet has now an invalid header line.
Any ideas?
version: kamailio 5.6.1 (x86_64/linux)
Best regards,
Bernd
Hello,
the Via header is a bit of a special one, as its obviously also added from the Kamailio server during relay or other operations. This might interfere with the textops remove_hf operation.
What is your goal that you want to achieve? There might be another way to doing it.
Cheers,
Henning
Hello Henning,
thanks for your response.
We had a problem were a BYE was not sended by the pbx. So I wanted to test if it makes a difference if only the Record-Route entry is in the header of the INVITE.
But in general, I will call this a bug in kamailio.
There is nothing written about corner cases in the documentation. If I use remove_hf() I assume that it works. If I can not trust what it is written in the documentation, I have to check each SIP packet for inconsistencies if I use an additional command in the cfg file.
2 possibilities: 1. Add this behaviour in the documentation (bad, but ok) 2. The command should work as described.
Best regards,
Bernd
Am 09.08.2022 um 21:59 schrieb Henning Westerholt:
Hello,
the Via header is a bit of a special one, as its obviously also added from the Kamailio server during relay or other operations. This might interfere with the textops remove_hf operation.
What is your goal that you want to achieve? There might be another way to doing it.
Cheers,
Henning
Hi Bernd,
The Via header is mandatory according to RFC 3261, section 20, in Requests:
Header field where proxy ACK BYE CAN INV OPT REG ___________________________________________________________________ [..] Via R amr m m m m m m
You are asking Kamailio to do something that is against the standard. So, some people might expect that it's not working in this case, and I personally would not call it a Bug.
Documentation would be never fully complete for a complex software like Kamailio, sure. You could open a feature request or (even better) a pull request to improve the documentation for the textops module in the Kamailio github.
Cheers,
Henning
Hi,
if I remove only 1 of 2 it is not against the standard, because one Via header line is still inside.
But if I modify the documentation I would write:
"Attention: it is not working with a Via header field"
Then everyone thinks: ok, that is the only point where it will not work. But how can I, as not a kamailio programmer, can know if this is really the only case?
So I would also write something which is not 100% correct. This has to be done by a guy who knows this, and not by me as a kamailio learner.
Best regards,
Bernd
Am 11.08.2022 um 12:56 schrieb Henning Westerholt:
Hi Bernd,
The Via header is mandatory according to RFC 3261, section 20, in Requests:
Header field where proxy ACK BYE CAN INV OPT REG ___________________________________________________________________[..] Via R amr m m m m m m
You are asking Kamailio to do something that is against the standard. So, some people might expect that it's not working in this case, and I personally would not call it a Bug.
Documentation would be never fully complete for a complex software like Kamailio, sure. You could open a feature request or (even better) a pull request to improve the documentation for the textops module in the Kamailio github.
Cheers,
Henning
Hi Bernd,
Federrico already answered regarding the SIP part of the question.
Regarding the docs, if you are not feeling comfortable to add something by yourself feel free to create an issue and somebody else might pick it up and improve the docs.
Cheers,
Henning
Hi Bernd, as I said I am using it to remove Via headers inserted by previous hops since years with no issue.
Cheers,
Federico
On Thu, Aug 11, 2022 at 1:10 PM Bernd Krueger-Knauber bkk@ednt.de wrote:
Hi,
if I remove only 1 of 2 it is not against the standard, because one Via header line is still inside.
But if I modify the documentation I would write:
"Attention: it is not working with a Via header field"
Then everyone thinks: ok, that is the only point where it will not work. But how can I, as not a kamailio programmer, can know if this is really the only case?
So I would also write something which is not 100% correct. This has to be done by a guy who knows this, and not by me as a kamailio learner.
Best regards,
Bernd
Am 11.08.2022 um 12:56 schrieb Henning Westerholt:
Hi Bernd,
The Via header is mandatory according to RFC 3261, section 20, in
Requests:
Header field where proxy ACK BYE CAN INV OPT REG ___________________________________________________________________[..] Via R amr m m m m m m
You are asking Kamailio to do something that is against the standard.
So, some people might expect that it's not working in this case, and I personally would not call it a Bug.
Documentation would be never fully complete for a complex software like
Kamailio, sure.
You could open a feature request or (even better) a pull request to
improve the documentation for the textops module in the Kamailio github.
Cheers,
Henning
-- EDNT GmbH Werner-von-Siemens-Strasse 7 64625 Bensheim www.ednt.de
Registergericht: Darmstadt Registernummer: 24972
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I would argue that this is the documented behavior. The topmost via: is added during message assembly, and remove_hf() acts against the *received* message. The behavior of this is along the lines of:
append_hf("X-Fake-Header: Foo"); remove_hf("X-Fake-Header");
I don't think that the reason it can't be removed in the manner requested has to do directly with RFC compliance, but rather the way Kamailio's architecture processes messages. Could we have more clarification and better documentation around this fact? Sure. Is it a bug? Since Kamailio's reason for being is to function as a SIP proxy, and proper insertion of the Via: header is usually critical to that function it wouldn't seem so.
Kaufman
From: sr-users sr-users-bounces@lists.kamailio.org On Behalf Of Federico Cabiddu Sent: Thursday, August 11, 2022 6:31 AM To: Kamailio (SER) - Users Mailing List sr-users@lists.kamailio.org Subject: Re: [SR-Users] remove_hf() does not remove the complete line
Hi Bernd, as I said I am using it to remove Via headers inserted by previous hops since years with no issue.
Cheers,
Federico
On Thu, Aug 11, 2022 at 1:10 PM Bernd Krueger-Knauber <bkk@ednt.demailto:bkk@ednt.de> wrote: Hi,
if I remove only 1 of 2 it is not against the standard, because one Via header line is still inside.
But if I modify the documentation I would write:
"Attention: it is not working with a Via header field"
Then everyone thinks: ok, that is the only point where it will not work. But how can I, as not a kamailio programmer, can know if this is really the only case?
So I would also write something which is not 100% correct. This has to be done by a guy who knows this, and not by me as a kamailio learner.
Best regards,
Bernd
Am 11.08.2022 um 12:56 schrieb Henning Westerholt:
Hi Bernd,
The Via header is mandatory according to RFC 3261, section 20, in Requests:
Header field where proxy ACK BYE CAN INV OPT REG ___________________________________________________________________[..] Via R amr m m m m m m
You are asking Kamailio to do something that is against the standard. So, some people might expect that it's not working in this case, and I personally would not call it a Bug.
Documentation would be never fully complete for a complex software like Kamailio, sure. You could open a feature request or (even better) a pull request to improve the documentation for the textops module in the Kamailio github.
Cheers,
Henning
-- EDNT GmbH Werner-von-Siemens-Strasse 7 64625 Bensheim www.ednt.dehttps://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ednt.de%2F&data=05%7C01%7Cbkaufman%40bcmone.com%7C6f4c1458c1e94ec20e3208da7b8d21af%7Cafc1818e7b6848568913201b9396c4fc%7C1%7C0%7C637958143348606038%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=B8QM%2BsRxyJNn6vRa8UnQEDs2bcfW1u4eaPdCOLGWVZY%3D&reserved=0
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Hi Bernd, I am using remove_hf{"Via") without any issue to remove Via headers added from previous hops. As explained by Henning you cannot remove the Via that kamailio has to insert as a proxy, also because, by rfc, the Via is used to relay back the replies. If Kamailio would not insert its own Via in an outgoing message, the receiving hop would have no way of responding to the request.
Cheers,
Federico
On Thu, Aug 11, 2022 at 12:21 PM Bernd Krueger-Knauber bkk@ednt.de wrote:
Hello Henning,
thanks for your response.
We had a problem were a BYE was not sended by the pbx. So I wanted to test if it makes a difference if only the Record-Route entry is in the header of the INVITE.
But in general, I will call this a bug in kamailio.
There is nothing written about corner cases in the documentation. If I use remove_hf() I assume that it works. If I can not trust what it is written in the documentation, I have to check each SIP packet for inconsistencies if I use an additional command in the cfg file.
2 possibilities:
- Add this behaviour in the documentation (bad, but ok)
- The command should work as described.
Best regards,
Bernd
Am 09.08.2022 um 21:59 schrieb Henning Westerholt:
Hello,
the Via header is a bit of a special one, as its obviously also added
from the Kamailio server during relay or other operations. This might interfere with the textops remove_hf operation.
What is your goal that you want to achieve? There might be another way
to doing it.
Cheers,
Henning
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Kaufman