Variables: Socket cookie variable for debugging purposes

[Maxim Dounin]

Hello!

On Fri, Jul 07, 2017 at 10:28:42PM +0300, Donatas Abraitis wrote:

> this looks promising when new 4.12 kernel introduced SO_COOKIE socket
> option which is able to generate a cookie for the socket.
> 
> More information and implementation is here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5daab9db7b65df87da26fd8cfa695fb9546a1ddb
> 
> Waiting for comments.
> 
> # HG changeset patch
> # User Donatas Abraitis <donatas.abraitis at gmail.com>
> # Date 1499424023 -10800
> #      Fri Jul 07 13:40:23 2017 +0300
> # Node ID 55b401978df27f1a1ab4eee4e50615b7551e3c0b
> # Parent  70e65bf8dfd7a8d39aae8ac3a209d426e6947735
> Add new `socket_cookie` variable
> 
> This would be useful for tracking connections by cookie, not only by
> request_id as we have it right now. Related:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5daab9db7b65df87da26fd8cfa695fb9546a1ddb

It is not clear if such a variable is indeed beneficial, and how 
it can be used.  Shouldn't client's address with port be good 
enough to identify a connection, at least in most practical cases?

If you think it worth adding, please elaborate a bit more on how 
it is expected to be used.

Alternatively, consider providing a module which exposes the 
variable, it should be trivial to implement.

[...]

-- 
Maxim Dounin
http://nginx.org/