Re: [Qemu-devel] [PATCH v2 2/5] sockets: don't block IPv4 clients when listening on "::"

[Eric Blake]

On 05/19/2017 01:03 PM, Daniel P. Berrange wrote:
> When inet_parse() parses the hostname, it is forcing the
> has_ipv6 && ipv6 flags if the address contains a ":". This
> means that if the user had set the ipv4=on flag, to try to
> restrict the listener to just ipv4, an error would not have
> been raised.  eg
> 
>    -incoming tcp:[::]:9000,ipv4
> 
> should have raised an error because listening for IPv4
> on "::" is a non-sensical combination.

If I understand correctly, the correct response (and post-patch
behavior) is an error (mismatch between requesting IPv4-only usage while
giving an IPv6 address), but the buggy response (pre-patch behavior) is
that we ended up setting ipv6 in addition to the user-set ipv4 (because
we found a ':'), and then end up listening on IPv6 after all contrary to
the user's request.


> With this removed,
> we now call getaddrinfo() on "::" passing PF_INET and
> so getaddrinfo reports an error about the hostname being
> incompatible with the requested protocol.
> 
> Likewise it is explicitly setting the has_ipv4 & ipv4
> flags when the address contains only digits + '.'. This
> has no ill-effect, but also has no benefit, so is removed.
> 
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
>  util/qemu-sockets.c | 4 ----
>  1 file changed, 4 deletions(-)

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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