Re: [PATCH v5 04/13] arp: Check all configured addresses in ARP filtering

[David Gibson <david@gibson.dropbear.id.au>]

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On Sun, Feb 22, 2026 at 12:44:36PM -0500, Jon Maloy wrote:
> As a preparation for handling multiple addresses, we update ignore_arp()
> to check against all addresses in the unified addrs[] array using the
> for_each_addr() macro.
> 
> Signed-off-by: Jon Maloy <jmaloy@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

The patch is correct, but it can be made slightly more elegant, see
below.

> 
> ---
> v3: Adapted to single-array changes earlier in this series
> ---
>  arp.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arp.c b/arp.c
> index 99a6a67..8beb2dd 100644
> --- a/arp.c
> +++ b/arp.c
> @@ -41,7 +41,7 @@
>  static bool ignore_arp(const struct ctx *c,
>  		       const struct arphdr *ah, const struct arpmsg *am)
>  {
> -	struct inany_addr_entry *e = first_v4(c);
> +	const struct inany_addr_entry *e;
>  
>  	if (ah->ar_hrd != htons(ARPHRD_ETHER)	||
>  	    ah->ar_pro != htons(ETH_P_IP)	||
> @@ -55,9 +55,10 @@ static bool ignore_arp(const struct ctx *c,
>  	    !memcmp(am->sip, am->tip, sizeof(am->sip)))
>  		return true;
>  
> -	/* Don't resolve the guest's assigned address, either. */
> -	if (e && !memcmp(am->tip, inany_v4(&e->addr), sizeof(am->tip)))
> -		return true;
> +	/* Don't resolve any of the guest's addresses */
> +	for_each_addr(e, c, AF_INET)
> +		if (!memcmp(am->tip, inany_v4(&e->addr), sizeof(am->tip)))
> +			return true;

You can avoid the somewhat awkward for_each_addr(AF_INET) logic, by
using inany_equals4() on *every* entry in the address array.  The IPv6
addresses necessarily won't match.

>  	return false;
>  }
> -- 
> 2.52.0
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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