Re: error from ntpd upon IPv6 address receipt/bind

[masanobu%iij.ad.jp@localhost]

Should we move to tech-net@ for this discussion?

From: masanobu%iij.ad.jp@localhost
Subject: Re: error from ntpd upon IPv6 address receipt/bind
Date: Tue, 25 May 2010 19:24:52 +0900 (JST)

> 
>  Hi.
> 
>  Until a DAD completes, the address is marked as 
> "tentative(IN6_IFF_TENTATIVE)"
> and bind() with the address fails. This is the reason why ntpd sometimes
> complains about an address.
> 
>  Some daemon programs check the routing socket and do bind() after getting
> RTM_NEWADDR. For IPv4, it's no problem. For IPv6, if a daemon do the same
> thing like IPv4, it may fail. It depends on the timing.
> 
>  And, perhaps all *BSD's routing socket's implement don't have the way to
> inform the changing from tentative to preferred (== DAD completed and OK to
> use).
> 
>  To do this, there are 3 (or more?) solutions:
> 
>  A)  Make a new routing message (RTM_ADDRINFO?) for a transistion from
>     tentative to preferred.
> 
>      If we have this message, bind()ing after getting the new message
>     solves the problem.
> 
>  B)  Don't send RTM_NEWADDR when an address is added as tentative and send
>     it after transistion from tentative to preferred.
> 
>  C) Send RTM_NEWADDR for both timing.
> 
> 
>         none->tentative tentative->preferred
> current RTM_NEWADDR     -
> A)      RTM_NEWADDR     RTM_ADDRINFO
> B)      -               RTM_NEWADDR
> C)      RTM_NEWADDR     RTM_NEWADDR
> 
> 
>  I think B) and C) is not good because the timing is not the time WHEN
> A NEW ADDRESS IS ASSIGNED.
> 
>  If we choice A) some programs that strictly check incoming routing messages
> may crash e.g.:
> 
>  switch(rtm->rtm_type) {
>  case RTM_NEWADDR:
>  case RTM_DELADDR:
>  case RTM_ADD:
>  .
>  .
>  .
>       break;
>  deafult:
>       perror("damn");
>       exit(1);
>  }
> 
> How should we solve it?
> 
> ----------------------------------------------------------
>               SAITOH Masanobu (masanobu%iij.ad.jp@localhost
>                                 msaitoh%netbsd.org@localhost)

----------------------------------------------------------
                SAITOH Masanobu (masanobu%iij.ad.jp@localhost
                                  msaitoh%netbsd.org@localhost)