Re: [PATCH 2/3] icmp: Flow based error reporting

[Stefano Brivio <sbrivio@redhat.com>]

On Fri, 8 Mar 2024 11:49:27 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Fri, Mar 08, 2024 at 12:26:40AM +0100, Stefano Brivio wrote:
> > On Thu, 29 Feb 2024 15:15:33 +1100
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> >   
> > > Use flow_dbg() and flow_err() helpers to generate flow-linked error
> > > messages in most places.  Make a few small improvements to the messages
> > > while we're at it.  This allows us to avoid the awkward 'pname' variables
> > > since whether we're dealing with ICMP or ICMPv6 is already built into the
> > > flow type which these helpers include.
> > > 
> > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > > ---
> > >  icmp.c | 31 ++++++++++++++-----------------
> > >  1 file changed, 14 insertions(+), 17 deletions(-)
> > > 
> > > diff --git a/icmp.c b/icmp.c
> > > index 1caf791d..63adafcf 100644
> > > --- a/icmp.c
> > > +++ b/icmp.c
> > > @@ -61,7 +61,6 @@ void icmp_sock_handler(const struct ctx *c, sa_family_t af, union epoll_ref ref)
> > >  {
> > >  	struct icmp_ping_flow *pingf = af == AF_INET
> > >  		? icmp_id_map[V4][ref.icmp.id] : icmp_id_map[V6][ref.icmp.id];
> > > -	const char *const pname = af == AF_INET ? "ICMP" : "ICMPv6";
> > >  	union sockaddr_inany sr;
> > >  	socklen_t sl = sizeof(sr);
> > >  	char buf[USHRT_MAX];
> > > @@ -75,8 +74,7 @@ void icmp_sock_handler(const struct ctx *c, sa_family_t af, union epoll_ref ref)
> > >  
> > >  	n = recvfrom(ref.fd, buf, sizeof(buf), 0, &sr.sa, &sl);
> > >  	if (n < 0) {
> > > -		warn("%s: recvfrom() error on ping socket: %s",
> > > -		     pname, strerror(errno));
> > > +		flow_err(pingf, "recvfrom() error: %s", strerror(errno));
> > >  		return;
> > >  	}
> > >  	if (sr.sa_family != af)
> > > @@ -113,8 +111,9 @@ void icmp_sock_handler(const struct ctx *c, sa_family_t af, union epoll_ref ref)
> > >  		pingf->seq = seq;
> > >  	}
> > >  
> > > -	debug("%s: echo reply to tap, ID: %"PRIu16", seq: %"PRIu16, pname,
> > > -	      ref.icmp.id, seq);
> > > +	flow_dbg(pingf, "echo reply to tap, ID: %"PRIu16", seq: %"PRIu16,
> > > +		 ref.icmp.id, seq);
> > > +
> > >  	if (af == AF_INET)
> > >  		tap_icmp4_send(c, sr.sa4.sin_addr, tap_ip4_daddr(c), buf, n);
> > >  	else if (af == AF_INET6)
> > > @@ -123,7 +122,7 @@ void icmp_sock_handler(const struct ctx *c, sa_family_t af, union epoll_ref ref)
> > >  	return;
> > >  
> > >  unexpected:
> > > -	warn("%s: Unexpected packet on ping socket", pname);
> > > +	flow_err(pingf, "Unexpected packet on ping socket");
> > >  }
> > >  
> > >  /**
> > > @@ -158,7 +157,6 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
> > >  					    struct icmp_ping_flow **id_sock,
> > >  					    sa_family_t af, uint16_t id)
> > >  {
> > > -	const char *const pname = af == AF_INET ? "ICMP" : "ICMPv6";
> > >  	uint8_t flowtype = af == AF_INET ? FLOW_PING4 : FLOW_PING6;
> > >  	union icmp_epoll_ref iref = { .id = id };
> > >  	union flow *flow = flow_alloc();
> > > @@ -195,9 +193,9 @@ static struct icmp_ping_flow *icmp_ping_new(const struct ctx *c,
> > >  	if (pingf->sock > FD_REF_MAX)
> > >  		goto cancel;
> > >  
> > > -	*id_sock = pingf;
> > > +	flow_dbg(pingf, "new socket %i for echo ID %"PRIu16, pingf->sock, id);
> > >  
> > > -	debug("%s: new socket %i for echo ID %"PRIu16, pname, pingf->sock, id);
> > > +	*id_sock = pingf;
> > >  
> > >  	return pingf;
> > >  
> > > @@ -222,7 +220,6 @@ 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)
> > >  {
> > > -	const char *const pname = af == AF_INET ? "ICMP" : "ICMPv6";
> > >  	union sockaddr_inany sa = { .sa_family = af };
> > >  	const socklen_t sl = af == AF_INET ? sizeof(sa.sa4) : sizeof(sa.sa6);
> > >  	struct icmp_ping_flow *pingf, **id_sock;
> > > @@ -276,13 +273,13 @@ int icmp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
> > >  
> > >  	pingf->ts = now->tv_sec;
> > >  
> > > -	if (sendto(pingf->sock, pkt, plen, MSG_NOSIGNAL, &sa.sa, sl) < 0) {
> > > -		debug("%s: failed to relay request to socket: %s",
> > > -		      pname, strerror(errno));
> > > -	} else {
> > > -		debug("%s: echo request to socket, ID: %"PRIu16", seq: %"PRIu16,
> > > -		      pname, id, seq);
> > > -	}
> > > +	if (sendto(pingf->sock, pkt, plen, MSG_NOSIGNAL, &sa.sa, sl) < 0)
> > > +		flow_dbg(pingf, "failed to relay request to socket: %s",
> > > +			 strerror(errno));
> > > +	else
> > > +		flow_dbg(pingf,
> > > +			 "echo request to socket, ID: %"PRIu16", seq: %"PRIu16,
> > > +			 id, seq);  
> > 
> > I can add the usual curly brackets on merge. The rest of the series
> > looks good to me.  
> 
> Thanks.  It may take me a minute to internalise the "braces if > 1
> physical line" rule.

It took me years. I mean, we don't have to adhere to "Linux -net"
style, but it has a couple of advantages such as being somewhat
formalised and the existence of checkpatch.pl. I also happen to be
familiar with it.

If we decide not to, though, then we should probably fix up everything
at once.

-- 
Stefano