[pkg-x2go-devel] Bug#766299: nxproxy: BIG-REQUESTS patch builds but fails at runtime

[Mike Gabriel]

Hi Paul,

On  Di 28 Okt 2014 08:09:16 CET, paul.szabo wrote:

> Dear Mike,
>
>>> You have the new, patched nxproxy on both ends of the connection?
>>> The encoding of the data has changed.
>> ...
>> nxagent and nxproxy are installed onto different systems from
>> different sources ...
>> So, this should be handled by your code then, I guess.
>
> The encoding must change: some lengths must be sent; with BIG-REQUEST
> they can be larger than 16 bits; and (for super-efficiency reasons?)
> they were encoded into just 16 bits. I see no work-around other than
> to change the encoding to 32 bits, as I did in my patch. Please let
> me know if you can think of some other way.
>
> The best that could be done is for nxproxy to detect the version used
> on the other end, and refuse to talk if they did not match. Please let
> me know if you think that would be worthwhile to pursue.
>
> In the past, I see exactly similar, incompatible version changes, e.g.:
>  - dxpc 3.9.0 being incompatible with earlier versions
>    http://www.vigor.nu/dxpc/README
>  - NX 3.5.0 issues with NoMachine 4
>    https://www.nomachine.com/AR10I00603
> I guess such is the price of progress, of having made the wrong design
> choices (as seen in hindsight).
>
> Cheers, Paul

We plan to crowd-fund a rewrite of NX. I made arrangements with Keith  
Packard (Mr. X.Org) on DebConf13 in Switzerland that once we come up  
with an integrative solution, he will support us with getting our NX  
rewrite into X.Org upstream.

If it is not possible to dynamically detect if 16 or 32 bit encoding  
is used on the server-side (the client-side should be the flexible  
part), then your patch has to wait for that rewrite to come (a design  
change then is absolutely ok and wanted). I don't think we should  
break compatibility within the 3.5.0.x release series.

So again, do you see an option for detecting the server-side encoding  
(or querying it or triggering/enforcing it via a nxagent cmdline  
option)?

Thanks once more for working on this!!!
Mike

PS: How do you test if the BIG-REQUESTS implementation works? With  
TexPower, you said. What do I have to do to trigger the BIG-REQUESTS  
bug if nx is not patched?


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