Re: [PATCH v5 15/29] dhcpv6: Convert to iov_tail

[Stefano Brivio <sbrivio@redhat.com>]

On Thu, 17 Apr 2025 18:51:22 +0200
Laurent Vivier <lvivier@redhat.com> wrote:

> Use packet_data() and extract headers using IOV_REMOVE_HEADER()
> and IOV_PEEK_HEADER() rather than packet_get().
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  dhcpv6.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/dhcpv6.c b/dhcpv6.c
> index 549ddbbea735..a52af1b7a0fe 100644
> --- a/dhcpv6.c
> +++ b/dhcpv6.c
> @@ -534,9 +534,15 @@ 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;

Same as the comment to 10/29: how bad would it be to call those
mh_storage and uh_storage?

>  	size_t mlen, n;
>  
> -	uh = packet_get(p, 0, 0, sizeof(*uh), &mlen);
> +	if (!packet_data(p, 0, &data))
> +		return -1;
> +
> +	uh = IOV_REMOVE_HEADER(&data, uhc);
>  	if (!uh)
>  		return -1;
>  
> @@ -549,6 +555,7 @@ int dhcpv6(struct ctx *c, const struct pool *p,
>  	if (!IN6_IS_ADDR_MULTICAST(daddr))
>  		return -1;
>  
> +	mlen = iov_tail_size(&data);
>  	if (mlen + sizeof(*uh) != ntohs(uh->len) || mlen < sizeof(*mh))
>  		return -1;
>  
> @@ -556,7 +563,7 @@ 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;
>  

-- 
Stefano