Hi,

The reason for making this change is that we have some customers who are
still using IPv4 and are trialling IPv6 but do not want any traffic going
to those (IPv6) servers during this time. However the DNS server will
still return A and AAAA records.

Thanks,
Alan

On 01/09/2015 22:16, "curl-library on behalf of Daniel Stenberg"
<curl-library-bounces_at_cool.haxx.se on behalf of daniel_at_haxx.se> wrote:

>On Thu, 27 Aug 2015, Alan Cronin (alcronin) wrote:
>
>Howdy! Sorry for responding so slowly.
>
>> The change involves adding an option to Curl (something like
>> CURLOPT_IP_FAMILY_PREFERENCE) which would allow a preference of IPv4 vs
>>IPv6
>> to be set for the first connection in a dual stack environment. This
>> functionality would extend the happy eyeballs algorithm.
>>
>> There is already an CURLOPT_IPRESOLVE option which limits the IP
>>version but
>> this new option is more a preference in the case there is both an IPv4
>>and
>> IPv6 interface for the connection.
>>
>> We propose making a change to connect.c::Curl_connecthost() and reorder
>>the
>> conn->tempaddr object before calling singleipconnect() based on the
>>option
>> set by the consumer.
>>
>> What are your thoughts on this proposal?
>
>I'm not opposed adding an option like this, but still, can you tell us
>something about the motivation/need for this so that we understand it
>better?
>Happy Eyeballs is after all explicitly designed to slightly favor IPv6.
>
>--
>
> / daniel.haxx.se
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Received on 2015-09-03