upstart-socket-bridge doesn't support ipv6 sockets

[Steve Langasek]

Playing with upstart-socket-bridge to see if it's a solution for avoiding polling in the Ubuntu cups post-start (bug #855010), I find that the socket bridge only supports inet and unix sockets - it does not support inet6 sockets. As a result, it's impossible to use socket initialization for an ipv6 service... which nowadays should be approximately all services.

If we want socket initialization to be a viable option for services, ipv6 support is a must.

[Kai Mast (kai-mast)]

Just wondering. I am not familiar with the upstart codebase, but this seems rather trivial to fix. Where is the problem here?

[Dimitri John Ledkov (xnox)]

On 31 December 2013 13:20, Kai Mast <email address hidden> wrote:
> Just wondering. I am not familiar with the upstart codebase, but this
> seems rather trivial to fix. Where is the problem here?
>

The whole upstart socket bridge is a single C file in the upstart codebase:

https://bazaar.launchpad.net/+branch/upstart/view/head:/extra/upstart-socket-bridge.c

As the rest of the code base it heavily uses libnih library. Some
introduction / documentation about that library can be found at:

http://people.canonical.com/~jhunt/presentations/uds-r/2012-10-31/upstart-development.pdf

http://libnih.la/

--
Regards,

Dimitri.

[Kai Mast (kai-mast)]

Thanks for the info Dimitri.
I looked at the code and still think this can be resolved by adding a case for AF_INET6 to both switches.

Sadly, I have no idea how to test/debug upstart. Otherwise, I would definitly give this a try...

[Bartosz Kosiorek (gang65)]

@Kai Mast
According to /sys/socket.h definition:
http://unix.superglobalmegacorp.com/Net2/newsrc/sys/socket.h.html

there isn't AF_INET6 declarations.

In "Address families" section there are only:
#define AF_INET 2 /* internetwork: UDP, TCP, etc. */

[Bartosz Kosiorek (gang65)]

Latest sys/socket.h is described here:
http://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/socket.h.html

And there are AF_INET6 declaration.
Sorry for cofusion.

[Kai Mast (kai-mast)]

The linked branch builds now. I cannot find any tests for upstart socket bride, so I don't really now how to verify it is working. Any help?

Btw, here is a good tutorial how to convert code to IPv6: http://uw714doc.sco.com/en/SDK_netapi/sockC.PortIPv4appIPv6.html

[Bartosz Kosiorek (gang65)]

I look at your code and here is my remarks:
1. Line 335:
  char buffer[INET6_ADDRSTRLEN];
use nih_local. It shoul looks like:
  nih_local char buffer[INET6_ADDRSTRLEN];

2. Line 72, 73
  Add comment with description of the variables sin6_addr and sin_addr

3. Line 539-546
  Fix identation. You could follow Coding style section in HACKING file

4. Update ChangeLog file

5. Update man files (with additional examples of the IPv6 usage) in directory: extra/man/

[Cameron Norman (cameronnemo)]

So I made those tweaks you recommended, Bartosz.

Kai, you should install Ubuntu in a VM, install your Upstart branch from source, then write job that uses IPv6.

[Kai Mast (kai-mast)]

Thanks for picking this up cameron. Seem like you already tested it. Does it work?

Well, I was hoping there are some kind of unit tests for this.