interface ip arp

[Arnaud Lacombe]

Hi,

On Mon, May 2, 2011 at 4:03 AM, Li, Qing <qing.li at bluecoat.com> wrote:
> Please give this patch a try for IPv4 ARP
>
> http://people.freebsd.org/~qingli/arp2.patch
>
Your patch works; the manually added address is kept upon a up/down/up
transition. However, the interface address is still flush, which I
find inconsistent with it being marked 'permanent'.

 - Arnaud

> --Qing
>
> ________________________________________
> From: owner-freebsd-net at freebsd.org [owner-freebsd-net at freebsd.org] on behalf of Li, Qing
> Sent: Monday, May 02, 2011 12:45 AM
> To: Arnaud Lacombe
> Cc: freebsd-net at freebsd.org; Ingo Flaschberger
> Subject: RE: interface ip arp
>
> Your patch doesn't work because the in_lltable_prefix_free() is  a generic function.
>
> The static entries are kept only when issuing if-down command, however, if the interface
> address is being removed, permanent static entries are gone and have to be reinstalled.
>
> I already have a working patch for IPv4, just going over the IPv6 code.
>
> I will post the patch in a few minutes.
>
> -- Qing
>
> ________________________________________
> From: Arnaud Lacombe [lacombar at gmail.com]
> Sent: Monday, May 02, 2011 12:41 AM
> To: Li, Qing
> Cc: Ingo Flaschberger; freebsd-net at freebsd.org
> Subject: Re: interface ip arp
>
> Hi,
>
> On Sun, May 1, 2011 at 10:50 PM, Li, Qing <qing.li at bluecoat.com> wrote:
>> jeez, this bug has been around for quite a while ...
>>
>> Please try patch at  http://people.freebsd.org/~qingli/arp.patch
>>
> d'oh!... Concerning Ingo's bug, your patch do the job, my report was
> bad, 4.9-RELEASE and 7.x show the same behavior:
>
> # uname -a
> FreeBSD server 7.1-RELEASE-p13 FreeBSD 7.1-RELEASE-p13
> # ifconfig em0 up 192.168.45.200/24
> # arp -n 192.168.45.200
> ? (192.168.45.200) at 00:03:2d:16:6e:fc on em0 permanent [ethernet]
> # ifconfig em0 down
> # arp -n 192.168.45.200
> 192.168.45.200 (192.168.45.200) -- no entry
> # ifconfig em0 up
> # arp -n 192.168.45.200
> 192.168.45.200 (192.168.45.200) -- no entry
>
> The behavioral change I noticed is that permanent address (manually
> added) in the ARP table are flushed along with all other addresses on
>>8.x (cf. the script output of my previous mail) while they are kept
> in the cache on <7.x during a down/up transition. The following patch:
>
> diff --git a/sys/netinet/in.c b/sys/netinet/in.c
> index 1012012..27e44a2 100644
> --- a/sys/netinet/in.c
> +++ b/sys/netinet/in.c
> @@ -1372,6 +1372,8 @@ in_lltable_prefix_free(struct lltable *llt,
>
>        for (i=0; i < LLTBL_HASHTBL_SIZE; i++) {
>                LIST_FOREACH_SAFE(lle, &llt->lle_head[i], lle_next, next) {
> +                       if (lle->la_flags & LLE_STATIC)
> +                               continue;
>                        if (IN_ARE_MASKED_ADDR_EQUAL((struct
> sockaddr_in *)L3_ADDR(lle),
>                                                     pfx, msk)) {
>
> partially restores the old behavior. Only partially as before 8.x,
> interface addresses were not marked as 'permanent'. You could manually
> add a 'permanent' entry for this address in such a way it would
> survive the down/up transition. In 8.x, the interface address is
> marked as 'permanent', but is removed explicitly by arp_ifscrub(). So
> even the above change would not work for the interface address.
>
> Shouldn't this address be removed later when "removing all L2 entries
> on the given prefix", in which case it would not have to be re-added
> again, if marking it 'permanent' is deliberate ?
>
> Thanks,
>  - Arnaud
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