Re: [PATCH 08/18] icmp: Convert to iov_tail

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

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On Wed, Apr 02, 2025 at 07:23:33PM +0200, Laurent Vivier wrote:
> Use packet_base() and extract headers using IOV_PEEK_HEADER()
> rather than packet_get().
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  icmp.c | 38 +++++++++++++++++++++++---------------
>  1 file changed, 23 insertions(+), 15 deletions(-)
> 
> diff --git a/icmp.c b/icmp.c
> index 7e2b3423a8d1..119502c0c340 100644
> --- a/icmp.c
> +++ b/icmp.c
> @@ -241,24 +241,25 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
>  	struct icmp_ping_flow *pingf;
>  	const struct flowside *tgt;
>  	union sockaddr_inany sa;
> -	size_t dlen, l4len;
> +	struct iov_tail data;
> +	struct msghdr msh;
>  	uint16_t id, seq;
>  	union flow *flow;
>  	uint8_t proto;
> -	socklen_t sl;
> -	void *pkt;
>  
>  	(void)saddr;
>  	ASSERT(pif == PIF_TAP);
>  
> +	if (!packet_base(p, 0, &data))
> +		return -1;
> +
>  	if (af == AF_INET) {
>  		const struct icmphdr *ih;
> +		struct icmphdr ihc;
>  
> -		if (!(pkt = packet_get(p, 0, 0, sizeof(*ih), &dlen)))
> -			return 1;
> -
> -		ih =  (struct icmphdr *)pkt;
> -		l4len = dlen + sizeof(*ih);
> +		ih = IOV_PEEK_HEADER(&data, ihc);
> +		if (!ih)
> +			return -1;
>  
>  		if (ih->type != ICMP_ECHO)
>  			return 1;
> @@ -268,12 +269,11 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
>  		seq = ntohs(ih->un.echo.sequence);
>  	} else if (af == AF_INET6) {
>  		const struct icmp6hdr *ih;
> +		struct icmp6hdr ihc;
>  
> -		if (!(pkt = packet_get(p, 0, 0, sizeof(*ih), &dlen)))
> -			return 1;
> -
> -		ih = (struct icmp6hdr *)pkt;
> -		l4len = dlen + sizeof(*ih);
> +		ih = IOV_PEEK_HEADER(&data, ihc);
> +		if (!ih)
> +			return -1;
>  
>  		if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
>  			return 1;
> @@ -298,8 +298,16 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
>  	ASSERT(flow_proto[pingf->f.type] == proto);
>  	pingf->ts = now->tv_sec;
>  
> -	pif_sockaddr(c, &sa, &sl, PIF_HOST, &tgt->eaddr, 0);
> -	if (sendto(pingf->sock, pkt, l4len, MSG_NOSIGNAL, &sa.sa, sl) < 0) {
> +	ASSERT(data.off == 0);
> +	msh.msg_name = &sa;
> +	msh.msg_iov = (struct iovec *)data.iov;
> +	msh.msg_iovlen = data.cnt;
> +	msh.msg_control = NULL;
> +	msh.msg_controllen = 0;
> +	msh.msg_flags = 0;

I think we're going to want a helper to build a msghdr from an iov_tail.

> +
> +	pif_sockaddr(c, &sa, &msh.msg_namelen, PIF_HOST, &tgt->eaddr, 0);
> +	if (sendmsg(pingf->sock, &msh, MSG_NOSIGNAL) < 0) {
>  		flow_dbg_perror(pingf, "failed to relay request to socket");
>  	} else {
>  		flow_dbg(pingf,

-- 
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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