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

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Date:   Mon, 31 Jul 2017 09:27:55 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Phil Sutter <phil@....cc>
Cc:     Florian Lehner <dev@...-flo.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] ss: Enclose IPv6 address in brackets

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