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Date: Fri, 28 Feb 2014 13:44:43 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] socket: treat ipv4=on,
	ipv6=on uniformly
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org, stefanha@redhat.com

Il 28/02/2014 13:23, Gerd Hoffmann ha scritto:
> On Fr, 2014-02-28 at 11:16 +0100, Paolo Bonzini wrote:
>> In some cases, "ipv4=on,ipv6=on" means "try both kinds of address";
>> in others, it means "try IPv6 only" just by virtue of how the code
>> is structured.
>
>> @@ -127,10 +127,13 @@ int inet_listen_opts(QemuOpts *opts, int port_offset, Error **errp)
>
>> -    if (qemu_opt_get_bool(opts, "ipv4", 0))
>> -        ai.ai_family = PF_INET;
>> -    if (qemu_opt_get_bool(opts, "ipv6", 0))
>> -        ai.ai_family = PF_INET6;
>> +    if (qemu_opt_get_bool(opts, "ipv4", 0) != qemu_opt_get_bool(opts, "ipv6", 0)) {
>> +        if (qemu_opt_get_bool(opts, "ipv4", 0)) {
>> +            ai.ai_family = PF_INET;
>> +        } else {
>> +            ai.ai_family = PF_INET6;
>> +        }
>> +    }
>
> This is wrong for the listening side.
>
> ipv6 sockets can listen on both ipv4 and ipv6.  qemu configures ipv6
> sockets to do that, unconditionally.
>
> So ipv4=yes,ipv6=no works correctly.
> ipv4=yes,ipv6=yes works too.
> ipv4=no,ipv6=yes doesn't work, but to fix that you have to set the
> IPV6_V6ONLY socket option according to the ipv4 option.
>
> Canevat: Listening on both ipv4+ipv6 with a single file handle works for
> the wildcard address only.  Specifying -- say --
> host=localhost,ipv4=yes,ipv6=yes, then expect qemu to listen on both
> 127.0.0.1 and ::1 doesn't work.
>
> This can only be fixed by allowing multiple listening filehandles.
> Which is a non-trivial change as this also affects the public api (which
> will have to report a list of listening addresses instead of a single
> address).

Thanks for teaching me!

Do you think patch 2 is okay alone?

Paolo