Re: [PATCH 12/18] dhcpv6: Convert to iov_tail

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

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On Wed, Apr 02, 2025 at 07:23:37PM +0200, Laurent Vivier wrote:
> Use packet_base() and extract headers using IOV_REMOVE_HEADER()
> and IOV_PEEK_HEADER() rather than packet_get().
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  dhcpv6.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/dhcpv6.c b/dhcpv6.c
> index 373a98869f9b..eb3f188af0b5 100644
> --- a/dhcpv6.c
> +++ b/dhcpv6.c
> @@ -496,9 +496,15 @@ int dhcpv6(struct ctx *c, const struct pool *p,
>  	const struct msg_hdr *mh;
>  	const struct udphdr *uh;
>  	struct opt_hdr *bad_ia;
> +	struct iov_tail data;
> +	struct msg_hdr mhc;
> +	struct udphdr uhc;
>  	size_t mlen, n;
>  
> -	uh = packet_get(p, 0, 0, sizeof(*uh), &mlen);
> +	if (!packet_base(p, 0, &data))
> +		return -1;
> +
> +	uh = IOV_REMOVE_HEADER(&data, uhc);
>  	if (!uh)
>  		return -1;
>  
> @@ -511,6 +517,7 @@ int dhcpv6(struct ctx *c, const struct pool *p,
>  	if (!IN6_IS_ADDR_MULTICAST(daddr))
>  		return -1;
>  
> +	mlen = iov_tail_size(&data);

The total length is useful in enough cases that I wonder if it makes
sense for packet_base() to return it.

>  	if (mlen + sizeof(*uh) != ntohs(uh->len) || mlen < sizeof(*mh))
>  		return -1;
>  
> @@ -518,7 +525,7 @@ int dhcpv6(struct ctx *c, const struct pool *p,
>  
>  	src = &c->ip6.our_tap_ll;
>  
> -	mh = packet_get(p, 0, sizeof(*uh), sizeof(*mh), NULL);
> +	mh = IOV_PEEK_HEADER(&data, mhc);
>  	if (!mh)
>  		return -1;
>  

-- 
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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