Re: [PATCH 28/32] tcp_splice: Allow splicing of connections from IPv4-mapped loopback

[Stefano Brivio <sbrivio@redhat.com>]

On Wed, 16 Nov 2022 15:42:08 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> For non-spliced connections we now treat IPv4-mapped IPv6 addresses the
> same as the corresponding IPv4 addresses.  However currently we won't
> splice a connection from ::ffff:127.0.0.1 the way we would one from
> 127.0.0.1.  Correct this so that we can splice connections from IPv4
> localhost that have been received on an IPv6 dual stack socket.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  tcp_splice.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/tcp_splice.c b/tcp_splice.c
> index 7c2f667..61c56be 100644
> --- a/tcp_splice.c
> +++ b/tcp_splice.c
> @@ -514,19 +514,23 @@ bool tcp_splice_conn_from_sock(struct ctx *c, union epoll_ref ref,
>  			       struct tcp_splice_conn *conn, int s,
>  			       const struct sockaddr *sa)
>  {
> +	union inany_addr aany;
> +	const struct in_addr *a4;

The usual order.

> +	in_port_t port;

Is the port actually needed here? I don't see how you use it.

> +
>  	assert(c->mode == MODE_PASTA);
>  
> -	if (sa->sa_family == AF_INET6) {
> -		const struct sockaddr_in6 *sa6
> -			= (const struct sockaddr_in6 *)sa;
> -		if (!IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
> +	inany_from_sockaddr(&aany, &port, sa);
> +	a4 = inany_v4(&aany);
> +
> +	if (a4) {
> +		if (!IN4_IS_ADDR_LOOPBACK(a4))
>  			return false;
> -		conn->flags = SPLICE_V6;
> +		conn->flags = 0;
>  	} else {
> -		const struct sockaddr_in *sa4 = (const struct sockaddr_in *)sa;
> -		if (!IN4_IS_ADDR_LOOPBACK(&sa4->sin_addr))
> +		if (!IN6_IS_ADDR_LOOPBACK(&aany.a6))
>  			return false;
> -		conn->flags = 0;
> +		conn->flags = SPLICE_V6;
>  	}
>  
>  	if (setsockopt(s, SOL_TCP, TCP_QUICKACK, &((int){ 1 }),

-- 
Stefano