netdev - Re: [PATCH] ss: Enclose IPv6 address in brackets

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Message-ID: <20170731164328.GW16375@orbyte.nwl.cc>
Date:   Mon, 31 Jul 2017 18:43:28 +0200
From:   Phil Sutter <phil@....cc>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     Florian Lehner <dev@...-flo.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] ss: Enclose IPv6 address in brackets

On Mon, Jul 31, 2017 at 09:27:55AM -0700, Stephen Hemminger wrote:
> On Mon, 31 Jul 2017 12:30:10 +0200
> Phil Sutter <phil@....cc> wrote:
> 
> > On Sat, Jul 29, 2017 at 02:29:10PM +0200, Florian Lehner wrote:
> > > This patch adds support for RFC2732 IPv6 address format with brackets
> > > for the tool ss. So output for ss changes from
> > > 2a00:1450:400a:804::200e:443 to [2a00:1450:400a:804::200e]:443 for IPv6
> > > addresses with attached port number.
> > > 
> > > Signed-off-by: Lehner Florian <dev@...-flo.net>
> > > ---
> > >  misc/ss.c | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/misc/ss.c b/misc/ss.c
> > > index 12763c9..db39c93 100644
> > > --- a/misc/ss.c
> > > +++ b/misc/ss.c
> > > @@ -1059,7 +1059,11 @@ static void inet_addr_print(const inet_prefix *a,
> > > int port, unsigned int ifindex
> > >  			ap = format_host(AF_INET, 4, a->data);
> > >  		}
> > >  	} else {
> > > -		ap = format_host(a->family, 16, a->data);
> > > +		if (a->family == AF_INET6) {
> > > +			sprintf(buf, "[%s]", format_host(a->family, 16, a->data));
> > > +		} else {
> > > +			ap = format_host(a->family, 16, a->data);
> > > +		}
> > >  		est_len = strlen(ap);
> > >  		if (est_len <= addr_width)
> > >  			est_len = addr_width;  
> > 
> > Note that this will enclosed resolved hostnames in brackets as well, not
> > sure if that's intended. Looks like fixing that is not exactly trivial:
> > Hostname resolution is buried in format_host() which resides in
> > lib/utils.c so is shared code with ip, tc, etc. Hence, adding the
> > brackets in rt_addr_n2a_r() is not an option, either. Adding a 'bool *'
> > param to format_host() and format_host_r() indicating that name
> > resolution has happened might help here.
> > 
> > Cheers, Phil
> 
> Also, this code should return "*" for IN6ADDR_ANY

Oh, really? It doesn't do that currently, and I always thought the IPv6
all-zero address was written '::' (or '[::]:1234' if a port is present).

Cheers, Phil