[zeromq-dev] [PATCH] IPv6 changes to 4.0

[Steven McCoy]

Martin missed an updated patch from before, here it is again with some
extras.

* Fix NIC name binding always returning inaddr-any/in6addr-any.
* Binding upon a NIC name in IPv6 may resolve to multiple interfaces, use
the IPv6 scope identifier to force the bind.
* Use SO_BINDTODEVICE on Linux to workaround lack of in6addr_any:scope_id
support.
* Add support for IPv6 literal addresses.


*NIC NAME BINDING*

Basically NIC binding isn't too hot, so what we have here is when you bind
like this:

*./perf/local_thr tcp://eth0:5555 1 100000*

You are actually getting the same as this:

*./perf/local_thr tcp://*:5555 1 100000*

On Linux I have added a workaround that you can use system capabilities to
force the bind:

*sudo execcap 'cap_net_raw=ep' ./perf/local_thr tcp://eth0:5555 1 100000*
*
*
On modern distro's this utility has disappeared, the file system tools don't
appear to work out-of-the-box, but capsh does:

*sudo capsh --caps="cap_net_raw=ep" -- -c "./perf/local_thr tcp://eth0:5555
1 100000"*
*
*
That is the same capability as supporting ICMP, raw sockets, and IP/PGM.

To test simply try using another adapter such as loopback and it should wait
on reconnecting.

*./perf/remote_thr tcp://127.0.0.1:5555 1 100000*



*IPv6 LITERAL ADDRESSES*

Nothing particularly amazing, but to avoid confusion with port specifiers
the RFC recommend that all IPv6 literal addresses be enclosed within square
brackets.  Note in dual-stack mode IPv4 addresses are also valid.

Example:

*./perf/remote_thr tcp://[fe80::230:1bff:feb7:a209%eth0]:5555 1 100000*


*IPv6 LINK-LOCAL ADDRESSES*

The TCP stack isn't as forgiving as the UDP stack, when using link-local
addresses, even if you only have one available, the scope identifier must be
specified.

Valid:

*./perf/remote_thr tcp://[fe80::230:1bff:feb7:a209%eth0]:5555 1 100000*
*
*
Invalid:

*./perf/remote_thr tcp://[fe80::230:1bff:feb7:a209]:5555 1 100000*
Assertion failed: s == retired_fd (tcp_connecter.cpp:184)
Aborted


-- 
Steve-o
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