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

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

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On Thu, Nov 17, 2022 at 01:15:26AM +0100, Stefano Brivio wrote:
> 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.

Fixed.

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

Well, inany_from_sockaddr() requires a port parameter.  I could make
it accept NULL, but then I'd have some noise there instead of here.
Since inany_from_sockaddr() is an inline, I'm hoping the compiler will
be smart enough to elide it anyway.

I don't have a strong preference, I can change it if you'd like.

> 
> > +
> >  	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 }),
> 

-- 
David Gibson			| 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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