Re: [PATCH v9 09/30] icmp: Convert to iov_tail

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

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On Fri, Aug 08, 2025 at 04:01:21PM +0200, Laurent Vivier wrote:
> Use packet_data() and extract headers using IOV_PEEK_HEADER()
> rather than packet_get().
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  icmp.c | 40 +++++++++++++++++++++++++++-------------
>  iov.c  |  1 -
>  2 files changed, 27 insertions(+), 14 deletions(-)
> 
> diff --git a/icmp.c b/icmp.c
> index 95f38c1e2a3a..7791e88733d7 100644
> --- a/icmp.c
> +++ b/icmp.c
> @@ -44,6 +44,7 @@
>  
>  #define ICMP_ECHO_TIMEOUT	60 /* s, timeout for ICMP socket activity */
>  #define ICMP_NUM_IDS		(1U << 16)
> +#define MAX_IOV_ICMP		16 /* Arbitrary, should be enough */
>  
>  /**
>   * ping_at_sidx() - Get ping specific flow at given sidx
> @@ -238,28 +239,31 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
>  		     const void *saddr, const void *daddr,
>  		     const struct pool *p, const struct timespec *now)
>  {
> +	struct iovec iov[MAX_IOV_ICMP];
>  	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;
> +	int cnt;
>  
>  	(void)saddr;
>  	ASSERT(pif == PIF_TAP);
>  
> +	if (!packet_data(p, 0, &data))
> +		return -1;
> +
>  	if (af == AF_INET) {
> +		struct icmphdr ih_storage;
>  		const struct icmphdr *ih;
>  
> -		if (!(pkt = packet_get(p, 0, 0, sizeof(*ih), &dlen)))
> +		ih = IOV_PEEK_HEADER(&data, ih_storage);
> +		if (!ih)
>  			return 1;
>  
> -		ih =  (struct icmphdr *)pkt;
> -		l4len = dlen + sizeof(*ih);
> -
>  		if (ih->type != ICMP_ECHO)
>  			return 1;
>  
> @@ -267,14 +271,13 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
>  		id = ntohs(ih->un.echo.id);
>  		seq = ntohs(ih->un.echo.sequence);
>  	} else if (af == AF_INET6) {
> +		struct icmp6hdr ih_storage;
>  		const struct icmp6hdr *ih;
>  
> -		if (!(pkt = packet_get(p, 0, 0, sizeof(*ih), &dlen)))
> +		ih = IOV_PEEK_HEADER(&data, ih_storage);
> +		if (!ih)
>  			return 1;
>  
> -		ih = (struct icmp6hdr *)pkt;
> -		l4len = dlen + sizeof(*ih);
> -
>  		if (ih->icmp6_type != ICMPV6_ECHO_REQUEST)
>  			return 1;
>  
> @@ -285,6 +288,10 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
>  		ASSERT(0);
>  	}
>  
> +	cnt = iov_tail_clone(&iov[0], MAX_IOV_ICMP, &data);
> +	if (cnt < 0)
> +		return 1;
> +
>  	flow = flow_at_sidx(flow_lookup_af(c, proto, PIF_TAP,
>  					   af, saddr, daddr, id, id));
>  
> @@ -298,8 +305,15 @@ 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) {
> +	pif_sockaddr(c, &sa, &msh.msg_namelen, PIF_HOST, &tgt->eaddr, 0);
> +	msh.msg_name = &sa;
> +	msh.msg_iov = iov;
> +	msh.msg_iovlen = cnt;
> +	msh.msg_control = NULL;
> +	msh.msg_controllen = 0;
> +	msh.msg_flags = 0;
> +
> +	if (sendmsg(pingf->sock, &msh, MSG_NOSIGNAL) < 0) {
>  		flow_dbg_perror(pingf, "failed to relay request to socket");
>  	} else {
>  		flow_dbg(pingf,
> diff --git a/iov.c b/iov.c
> index 97e4ea733540..9d423d0f521e 100644
> --- a/iov.c
> +++ b/iov.c
> @@ -311,7 +311,6 @@ void *iov_remove_header_(struct iov_tail *tail, void *v, size_t len, size_t alig
>   *	   iov array, a negative value if there is not enough room in the
>   *	    destination iov array
>   */
> -/* cppcheck-suppress unusedFunction */
>  ssize_t iov_tail_clone(struct iovec *dst_iov, size_t dst_iov_cnt,
>  		       struct iov_tail *tail)
>  {

-- 
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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