netdev - Re: [PATCH net-next v4 3/3] net: ipv6: Use ip6_datagram_send

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Date:	Thu, 24 Apr 2014 17:06:57 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Lorenzo Colitti <lorenzo@...gle.com>
Cc:	Florent Fourcot <florent.fourcot@...t-bretagne.fr>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>,
	David Miller <davem@...emloft.net>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next v4 3/3] net: ipv6: Use ip6_datagram_send_common in ping.

On Wed, Apr 23, 2014 at 09:22:23PM +0900, Lorenzo Colitti wrote:
> On Wed, Apr 23, 2014 at 8:11 PM, Florent Fourcot
> <florent.fourcot@...t-bretagne.fr> wrote:
> > Le 22/04/2014 17:14, Lorenzo Colitti a écrit :> +
> >> +             if (sin6->sin6_family != AF_INET6)
> >> +                     return -EAFNOSUPPORT;
> >> +
> >
> > It has before returned -EINVAL, it changes the return to the user space.
> > You made it consistent with other protocols, but perhaps should you add
> > a notice in the commit changelog?
> 
> Actually I'm not sure what the correct value is. When you setsockopt
> IPV6_V6ONLY and then send to a mapped address, the error you get
> depends on what you're trying to do - ip6_datagram_connect returns
> EAFNOSUPPORT, but udpv6_sendmsg, dccp_v6_connect and tcp_v6_connect
> return ENETUNREACH. I think EINVAL is wrong. EAFNOSUPPORT is probably
> best because the code doesn't support dual-stack ping sockets, but it
> could.
> 
> There are probably very few users of this code at the moment, since
> the code was only released in 3.12, and support hasn't made it into
> iputils yet. And even there, ping just probably prints the error
> message and exits. So I don't think it's a big deal to change the
> return code.

Sure, but we don't know about other applications. Wouldn't it be just easier
and leave this as is for now and finally let ipv6 ping sockets also handle
ipv4? I looked at it some time ago and it didn't look complicated.

> >> -             if (sk->sk_bound_dev_if &&
> >> -                 sk->sk_bound_dev_if != u->sin6_scope_id) {
> >> -                     return -EINVAL;
> >> -             }
> >
> > What about this check now ?
> 
> I think that was incorrect. It would return EINVAL even if you did
> something as simple as:
> 
> - Open an IPv6 ping socket.
> - Bind it to eth0 with SO_BINDTODEVICE
> - Send a ping to 2001:: without specifying a scope id.

Agree with that.

Bye,

  Hannes

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