[SR-Users] SEMS license with kamailio and rtpengine

Sat Feb 12 01:36:44 CET 2022

Thanks all now I understand better.

to @Daniel-Constantin Mierla <miconda at gmail.com>  regarding to the compiled
lua code, I agree either it's an optimized binary or a dynamic .so. it
doesn't have to be GPL. But as discussed above, if you load the compiled
lua code into kamailio, it has to be GPL since it links to the C code
anyway directly, it calls kamailio functions directly (e.g. t_relay()) but
not via a socket, so that might applies to GPL unless that explicitly
clarified. even the kamailio config scripts also has this problem, since
kamailio config is not like *pure* config files e.g. .ini or .yaml, it has
it's own logic, it calls functions in C, it's just another "language" like
lua or js. The only difference is that the native config or lua code is not
compiled at the same time of kamailio, it would be interpreted at run time
by kamailio. but GPL doesn't care about compile time, it just cares if your
code "calls" GPL functions.

So if kamailio is not intended to restrict config or scripts via KEMI to
force GPL it might be good to explicitly clarify it?

Also thanks @Johansson, as the discussion is long I list my understanding
or my question #5 here. According to the answer that means when I write a
module to load into kamailio, I cannot link to libclosed.so as I cannot
provide source code since it's by a 3-rd party I cannot own the code and
it's not GPL. So the only way to use that libclosed.so with kamailio is to
create a service and communicate with kamailio via socket, evapi or http or
anything else.

On Thu, Feb 10, 2022 at 11:34 PM Daniel-Constantin Mierla <miconda at gmail.com>
wrote:

> I think it is not easy to impose any further restriction not to distribute
> the sources, but one can try ... in some (many) countries licenses and
> patents are not recognized or not enforced.
>
> Cheers,
> Daniel
> On 10.02.22 11:47, Alex Balashov wrote:
>
> Come to think of it, I imagine the license has language saying that it
> cannot be superseded in part or in whole by any contradictory agreement.
>
> —
> Sent from mobile, with due apologies for brevity and errors.
>
> On Feb 10, 2022, at 5:42 AM, Alex Balashov <abalashov at evaristesys.com>
> <abalashov at evaristesys.com> wrote:
>
>  Is it legally possible for a customer to separately contract away a
> right that the license otherwise affords them, such as the GPL right to
> demand source code and then turn around and distribute that source code?
>
> I have to wonder if it’s possible in the US. It seems like it shouldn’t
> be, but in principle, in the prevailing theme of Anglo-American
> jurisprudence, it’s possible to contract away pretty much anything, no
> matter how adverse to one’s interests, so long as it is done “freely”.
>
> —
> Sent from mobile, with due apologies for brevity and errors.
>
> On Feb 10, 2022, at 2:37 AM, Henning Westerholt <hw at gilawa.com>
> <hw at gilawa.com> wrote:
>
> 
>
> Hello,
>
>
>
> just to add to the discussion:
>
>
>
>    - Please have a look to the GPLv2 FAQ, many topics you’ve raised are
>    discussed there
>    https://www.gnu.org/licenses/old-licenses/gpl-2.0-faq.html
>    - You should really consult a lawyer for this specific questions
>
>
>
> Regarding the licence of the configuration (native script vs. KEMI) – my
> understanding would be that a native Kamailio cfg script would be
> independent of GPL as its interpreted (and practically the customer gets
> the “source code” anyway). But KEMI LUA code that is pre-compiled would
> fall under the GPL, so the customer has a right to get the source code for
> it. Compare e.g., to this:
> https://www.gnu.org/licenses/old-licenses/gpl-2.0-faq.html#IfInterpreterIsGPL
>
>
>
> Cheers,
>
>
>
> Henning
>
>
>
> --
>
> Henning Westerholt – https://skalatan.de/blog/
>
> Kamailio services – https://gilawa.com
>
>
>
> *From:* sr-users <sr-users-bounces at lists.kamailio.org>
> <sr-users-bounces at lists.kamailio.org> *On Behalf Of *Olle E. Johansson
> *Sent:* Thursday, February 10, 2022 8:13 AM
> *To:* Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
> <sr-users at lists.kamailio.org>
> *Subject:* Re: [SR-Users] SEMS license with kamailio and rtpengine
>
>
>
> Hi Seven!
>
> Note that many of these questions open a legal discussion that has been
> going on for many years. I base my answers on what I know, which may not be
> the full truth. Regardless, I have been involved in these kind of
> discussions for almost 30 years of working in open source.
>
>
>
> First, note that there are two kind of situations to observe. One is when
> your application is executing in a system. The other is the license of the
> written source code files.
>
>
>
> Secondly, license and copyright are two different things. You always have
> the copyright to your source code.
>
>
>
> In Kamailio there are source code files that have a different license than
> the rest of the files. That means that if you copy that source code and
> create a new product that license applies.
>
>
>
> Kamailio as a whole is released under GPL version 2. When you run Kamailio
> in your server, that license applies to it all, regardless of the license
> of various source code files.
>
>
>
> Also note that I base this discussion on a delivery of a system to a
> customer. When you run Kamailio as a service you do not deliver (according
> to GPL v2) and the customer doesn’t have the same rights to the source.
>
>
>
> Also note that (as other persons has pointed out) that it’s the recipient
> of the binaries that has the rights, not the world. If I am not your
> customer, I can’t demand the source code according to the GPL. The customer
> that receives the code has the right to do whatever they want with it -
> like publishing the source on GitHub for the world to enjoy.
>
>
>
>
>
>
>
> 10 feb. 2022 kl. 00:16 skrev Seven Du <dujinfang at gmail.com>:
>
>
>
> I have some questions on this, e.g. on Kamailio:
>
>
>
> 1. The core and some modules is GPL. I packaged that without change, and
> sell to a customer. and when the customer asks for source, I told him to
> download from the kamailio website, since I didn't change anything. Is
> that correct?
>
> How you distribute the source code to the customer is irrelevant here.
> Note that if you end up having to provide it on a floppy disk or a USB
> stick, you can charge for that according to the GPL :-)
>
>
>
> 2. I can also host the source on my own website, with some more helper
> scripts for building and packaging. That should be better?
>
> I can’t judge if it’s better or worse, it has very little relevance to
> with the license. Just make sure that you include the signatures made by
> the Kamailio team so the customer can trace it back to the source and make
> sure there’s no changes.
>
>
>
>
>
> 3. I write a new module, 100% code wrote from scratch, just follow the
> module guidelines or example code to expose/add hooks to core,  dynamically
> loaded into kamailio. Do I need to use GPL or can it be any license or even
> closed source? can I sell the standalone module in binary?
>
> Your source code has to be licensed in a license that can end up being
> compatible with GPL. You can not have a commercial license on it, since
> when executing it as part of Kamailio, GPL applies.
>
> Since your module ends up being GPL while running in a system you deliver
> for a fee or for free to your customer, your customers has a right to the
> source code.
>
>
>
>
>
>
>
> 4. my module still should be GPL since I have to call GPL code in kamailio
> source, e.g. string functions in core. or maybe it's ok if string functions
> in kamailio core is BSD?
>
> When executing ALL of Kamailio is GPL, including all linked modules.
>
>
>
>
>
> 5. If my module link to a 3rd party lib (e.g. libclosed-source.so or
> libclosed-source.a I think there's no difference?) which is not open source
> (but free to sell), can I sell it w/o the source of libclosed-source ?
>
> Linking means that you execute in the same processes and according to most
> this means that GPL applies. That’s why we have a lot of protocols where
> most people think that GPL does not apply, even though some people want to
> discuss that. In my personal view it’s ok to write commercial software that
> communicates over RPC or by using the http_client with Kamailio.
>
>
>
> In Asterisk, the license specially permits this use of the various
> Asterisk protocols since there was discussions. Most Asterisk developers
> believed it wasn’t necessary and that GPL did not apply when using protocol
> based API’s. But nevertheless, just to avoid discussions, this was
> clarified in the license.
>
>
>
> 6. If answer to 5 is yes, I can write my own libclosed-source and sell
> with whatever license?
>
> You can, but if it links to Kamailio in run-time, then it will at that
> point become GPL licensed regardless of what you have written. That’s why
> many companies stay away from GPL, especially libraries that are licensed
> with GPL, because it can affect your own licenses.
>
>
>
>
>
> 7. Regards to KEMI, if I write routing scripts with Lua (compiled with
> luac) and sell to a customer, should I open source the Lua code? The Lua
> code calls Kamailio core functions which might be GPL.
>
> That is an interesting question which I’m not ready to answer. I think the
> intention of the Kamailio dev team is that your code should not be affected
> by GPL, but we may want to clarify that.
>
>
>
> If you write a regular configuration script I would personally clearly
> think you have the rights to that. The idea with KEMI was to introduce
> modern ways of writing configuration scripts.
>
>
>
>
>
> Thanks. I don't mean to violate the GPL, just want to be clear and easier
> to understand the license.
>
> Always good to start the day with a GPL discussion :-)
>
>
>
> Cheers,
>
> /O
>
>
>
>
>
> On Wed, Feb 9, 2022 at 9:05 PM Henning Westerholt <hw at gilawa.com> wrote:
>
> Hello,
>
> (just to add the obvious disclaimer that this is not legal advice, I am
> not a lawyer).
>
> > [Would it be ok] if it were [using] a standalone service to which
> Kamailio interfaced using very narrowly confined and general-purpose
> communication channels?
>
> I do not think there is a problem regarding to the GPL in this case.
> Interfacing over SIP/HTTP/RPC/XMLRPC or other standard mechanism to a
> dedicated process would not establish a close coupling between Kamailio and
> the other code.
>
>
>
> I think it's correct. e.g. if you use evapi or http to talk to your
> service you don't have to open source your service code.
>
>
>
> Cheers,
>
> Henning
>
> --
> Henning Westerholt – https://skalatan.de/blog/
> Kamailio services – https://gilawa.com
>
> -----Original Message-----
> From: sr-users <sr-users-bounces at lists.kamailio.org> On Behalf Of Alex
> Balashov
> Sent: Wednesday, February 9, 2022 1:50 PM
> To: Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
> Subject: Re: [SR-Users] SEMS license with kamailio and rtpengine
>
>
> > On Feb 9, 2022, at 7:46 AM, Henning Westerholt <hw at gilawa.com> wrote:
> >
> >> If modules are designed to run linked together in a shared address
> space, that almost surely means combining them into one program.”
> >
> > This is exactly what applies to Kamailio due to the core and module
> architecture. The core and modules also share common data structures and
> memory segments.
>
> I see. So, practically, the only way a custom module could be considered
> meaningfully separate according to these criteria is if it were a
> standalone service to which Kamailio interfaced using very narrowly
> confined and general-purpose communication channels?
>
> — Alex
>
> --
> Alex Balashov | Principal | Evariste Systems LLC
>
> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
> Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
>
>
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>
>
> --
>
> About: http://about.me/dujinfang
> Blog: http://www.dujinfang.com
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>
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> --
> Daniel-Constantin Mierla -- www.asipto.comwww.twitter.com/miconda -- www.linkedin.com/in/miconda
> Kamailio Advanced Training - Online
>   Feb 21-24, 2022 (America Timezone)
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>
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