Re: [PATCH 7/7] netconfig: Control optimistic DAD

[Denis Kenzior <denkenz@gmail.com>]

Hi Andrew,

On 9/19/22 08:31, Andrew Zaborowski wrote:
> Enable or disable optimistic DAD for the interface using /proc.  Add
> l_netconfig_set_optimistic_dad_enabled() for the user to request that
> RFC 4429 optimistic DAD be enabled.  As recommended in the RFC, we'll
> only actually enable optimistic DAD for the automatic address generation
> methods and disable it if a static IPv6 address is configured.  The
> default if l_netconfig_set_optimistic_dad_enabled() isn't used is to
> disable optimistic DAD always.
> 
> Optimistic DAD can shorten practical IPv6 setup time by an amount on
> the order of a second by allowing the link-local address and the global
> address to be used immediately after being generated.  For the
> link-local address this means that DHCPv6 may start sooner and
> for the global address, which is added to the kernel by the
> L_NETCONFIG_EVENT_CONFIGURE event handler, the user can start
> establishing connections sooner.  With DHCPv6 and some luck the two
> savings may compound, with SLAAC only the global address's DAD time
> should matter.
> ---
>   ell/ell.sym     |  1 +
>   ell/netconfig.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
>   ell/netconfig.h |  2 ++
>   3 files changed, 51 insertions(+), 1 deletion(-)
> 

I went ahead and applied all patches in this series.  Question:

> @@ -1724,7 +1737,8 @@ static void netconfig_ifaddr_ipv6_added(struct l_netconfig *nc,
>   	struct in6_addr in6;
>   	_auto_(l_free) char *ip = NULL;
>   
> -	if (ifa->ifa_flags & IFA_F_TENTATIVE)
> +	if ((ifa->ifa_flags & IFA_F_TENTATIVE) &&
> +			!(ifa->ifa_flags & IFA_F_OPTIMISTIC))
>   		return;

This implies that we set the link local address even if it is still OPTIMISTIC. 
  Do we now need to update icmp6_send_router_solicitation() logic to make sure 
we do not include SLLAO from optimistic addresses?

>   
>   	if (!nc->started)

Regards,
-Denis