Re: DragonFly-2.1.1.346.g4d1d7 master usr.sbin/dntpd client.h defs.h dntpd.8 main.c socket.c

["Sepherosa Ziehau" <sepherosa@xxxxxxxxx>]

On Fri, Jan 9, 2009 at 8:47 PM, Simon 'corecode' Schubert
<corecode@fs.ei.tum.de> wrote:
> Sepherosa Ziehau wrote:
>>
>> On Fri, Jan 9, 2009 at 8:19 PM, Simon 'corecode' Schubert
>> <corecode@fs.ei.tum.de> wrote:
>>>
>>> Matthias Schmidt wrote:
>>>>
>>>> commit 4d1d74ba3c1fe85df343e4059c80bc704eec0312
>>>> Author: Matthias Schmidt <matthias@dragonflybsd.org>
>>>> Date:   Fri Jan 9 12:35:25 2009 +0100
>>>>
>>>>   Add IPv6 support to dntpd
>>>>       This commit allows dntpd to work with either IPv4 or IPv6 NTP
>>>> servers.  I added
>>>>   two new command line switches (-4/-6) to force dntpd to use only v4/v6
>>>> addresses.
>>>>   Thanks to sephe@ for some good hints.
>>>
>>> Are you sure this works if the ipv6 server is unreachable?  I don't think
>>> that a connect(2) on a udp socket will find that out.  You'd actually
>>> have
>>
>> udp_socket() only sets up a UDP socket; by calling connect(2) we could
>> receive ICMP error and use write(2) like functions.  As far as I
>> understand the code, it never intends to verify the reachability of
>> the server.
>
> But it has to do that now!  The DNS might return ipv6 and ipv4, but the ipv4
> one is only reachable.  So you *have* to check availability, otherwise it

Do you mean the host does not have global scope ipv6 unicast addresses
or the host does not have a valid default ipv6 route?  If that's what
you mean, connect(2) will fail on all resolved ipv6 server addresses.

Best Regards,
sephe

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