Re: [PATCH 2/3] udp: Unify some more inbound/outbound parts of udp_sock_init()

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

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On Tue, Oct 21, 2025 at 11:51:07PM +0200, Stefano Brivio wrote:
> On Fri, 17 Oct 2025 11:34:46 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > udp_sock_init() takes an 'ns' parameter determining if it creates a socket
> > in the guest namespace or host namespace.  Alter it to take a pif
> > parameter instead, like tcp_sock_init(), and use that change to slightly
> > reduce code duplication between the HOST and SPLICE cases.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  conf.c |  2 +-
> >  udp.c  | 60 +++++++++++++++++++++++++++++-----------------------------
> >  udp.h  |  5 +++--
> >  3 files changed, 34 insertions(+), 33 deletions(-)
> > 
> > diff --git a/conf.c b/conf.c
> > index 26f1bcc0..08cb50aa 100644
> > --- a/conf.c
> > +++ b/conf.c
> > @@ -171,7 +171,7 @@ static void conf_ports_range_except(const struct ctx *c, char optname,
> >  		if (optname == 't')
> >  			ret = tcp_sock_init(c, PIF_HOST, addr, ifname, i);
> >  		else if (optname == 'u')
> > -			ret = udp_sock_init(c, 0, addr, ifname, i);
> > +			ret = udp_sock_init(c, PIF_HOST, addr, ifname, i);
> >  		else
> >  			/* No way to check in advance for -T and -U */
> >  			ret = 0;
> > diff --git a/udp.c b/udp.c
> > index 86585b7e..49dd0144 100644
> > --- a/udp.c
> > +++ b/udp.c
> > @@ -1093,64 +1093,63 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,
> >  /**
> >   * udp_sock_init() - Initialise listening sockets for a given port
> >   * @c:		Execution context
> > - * @ns:		In pasta mode, if set, bind with loopback address in namespace
> > + * @pif:	Interface to open the socket for (PIF_HOST or PIF_SPLICE)
> >   * @addr:	Pointer to address for binding, NULL if not configured
> >   * @ifname:	Name of interface to bind to, NULL if not configured
> >   * @port:	Port, host order
> >   *
> >   * Return: 0 on (partial) success, negative error code on (complete) failure
> >   */
> > -int udp_sock_init(const struct ctx *c, int ns, const union inany_addr *addr,
> > -		  const char *ifname, in_port_t port)
> > +int udp_sock_init(const struct ctx *c, uint8_t pif,
> > +		  const union inany_addr *addr, const char *ifname,
> > +		  in_port_t port)
> >  {
> > +	int (*socks)[NUM_PORTS] = pif == PIF_HOST ?
> > +		udp_splice_init : udp_splice_ns;
> 
> Same as on v1: I'd rather avoid cramping ternary operators like this.

Good idea, done.

> >  	union udp_listen_epoll_ref uref = {
> > -		.pif = ns ? PIF_SPLICE : PIF_HOST,
> > +		.pif = pif,
> >  		.port = port,
> >  	};
> >  	int r4 = FD_REF_MAX + 1, r6 = FD_REF_MAX + 1;
> >  
> >  	ASSERT(!c->no_udp);
> >  
> > -	if (!addr && c->ifi4 && c->ifi6 && !ns) {
> > +	if (!addr && c->ifi4 && c->ifi6 && (pif == PIF_HOST)) {
> 
> I think it's more readable without the extra parentheses around the
> comparison, because when I see those I automatically think of an
> assignment we want to use in a conditional clause, but that's just a
> comparison.

Done.  Thomas Huth finally convinced me not to put precautionary
parens on anything next to && and ||, but I forgot this time :).

> 
> >  		int s;
> >  
> >  		/* Attempt to get a dual stack socket */
> >  		s = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, PIF_HOST,
> >  				NULL, ifname, port, uref.u32);
> > -		udp_splice_init[V4][port] = s < 0 ? -1 : s;
> > -		udp_splice_init[V6][port] = s < 0 ? -1 : s;
> > +		socks[V4][port] = s < 0 ? -1 : s;
> > +		socks[V6][port] = s < 0 ? -1 : s;
> >  		if (IN_INTERVAL(0, FD_REF_MAX, s))
> >  			return 0;
> >  	}
> >  
> >  	if ((!addr || inany_v4(addr)) && c->ifi4) {
> > -		if (!ns) {
> > -			r4 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, PIF_HOST,
> > -					 addr ? addr : &inany_any4, ifname,
> > -					 port, uref.u32);
> > +		const union inany_addr *a = addr ?
> > +			addr : &inany_any4;
> >  
> > -			udp_splice_init[V4][port] = r4 < 0 ? -1 : r4;
> > -		} else {
> > -			r4  = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, PIF_SPLICE,
> > -					  &inany_loopback4, ifname,
> > -					  port, uref.u32);
> > -			udp_splice_ns[V4][port] = r4 < 0 ? -1 : r4;
> > -		}
> > +		if (pif == PIF_SPLICE)
> > +			a = &inany_loopback4;
> > +
> > +		r4 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif, a, ifname,
> > +				 port, uref.u32);
> > +
> > +		socks[V4][port] = r4 < 0 ? -1 : r4;
> >  	}
> >  
> >  	if ((!addr || !inany_v4(addr)) && c->ifi6) {
> > -		if (!ns) {
> > -			r6 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, PIF_HOST,
> > -					 addr ? addr : &inany_any6, ifname,
> > -					 port, uref.u32);
> > +		const union inany_addr *a = addr ?
> > +			addr : &inany_any6;
> >  
> > -			udp_splice_init[V6][port] = r6 < 0 ? -1 : r6;
> > -		} else {
> > -			r6 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, PIF_SPLICE,
> > -					 &inany_loopback6, ifname,
> > -					 port, uref.u32);
> > -			udp_splice_ns[V6][port] = r6 < 0 ? -1 : r6;
> > -		}
> > +		if (pif == PIF_SPLICE)
> > +			a = &inany_loopback6;
> > +
> > +		r6 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif, a, ifname,
> > +				 port, uref.u32);
> > +
> > +		socks[V6][port] = r6 < 0 ? -1 : r6;
> >  	}
> >  
> >  	if (IN_INTERVAL(0, FD_REF_MAX, r4) || IN_INTERVAL(0, FD_REF_MAX, r6))
> > @@ -1216,7 +1215,8 @@ static void udp_port_rebind(struct ctx *c, bool outbound)
> >  
> >  		if ((c->ifi4 && socks[V4][port] == -1) ||
> >  		    (c->ifi6 && socks[V6][port] == -1))
> > -			udp_sock_init(c, outbound, NULL, NULL, port);
> > +			udp_sock_init(c, outbound ? PIF_SPLICE : PIF_HOST,
> > +				      NULL, NULL, port);
> >  	}
> >  }
> >  
> > diff --git a/udp.h b/udp.h
> > index 8f8531ad..f78dc528 100644
> > --- a/udp.h
> > +++ b/udp.h
> > @@ -17,8 +17,9 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif,
> >  		    sa_family_t af, const void *saddr, const void *daddr,
> >  		    uint8_t ttl, const struct pool *p, int idx,
> >  		    const struct timespec *now);
> > -int udp_sock_init(const struct ctx *c, int ns, const union inany_addr *addr,
> > -		  const char *ifname, in_port_t port);
> > +int udp_sock_init(const struct ctx *c, uint8_t pif,
> > +		  const union inany_addr *addr, const char *ifname,
> > +		  in_port_t port);
> >  int udp_init(struct ctx *c);
> >  void udp_timer(struct ctx *c, const struct timespec *now);
> >  void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s);
> 
> -- 
> Stefano
> 

-- 
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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