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 <[email protected]> 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 <[email protected]> On Behalf Of Olle E. 
> Johansson
> Sent: Thursday, February 10, 2022 8:13 AM
> To: Kamailio (SER) - Users Mailing List <[email protected]>
> 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 <[email protected]>:
>  
> 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 <[email protected]> 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 <[email protected]> On Behalf Of Alex 
> Balashov
> Sent: Wednesday, February 9, 2022 1:50 PM
> To: Kamailio (SER) - Users Mailing List <[email protected]>
> Subject: Re: [SR-Users] SEMS license with kamailio and rtpengine
> 
> 
> > On Feb 9, 2022, at 7:46 AM, Henning Westerholt <[email protected]> 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
> Proj:  http://www.freeswitch.org.cn
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