Re: [PATCH] conntrack: -L doesn't take a value, so don't discard one (same for -IUDGEFA)

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Sep 03, 2024 at 04:53:46PM +0200, Ahelenia Ziemiańska wrote:
> On Tue, Sep 03, 2024 at 10:22:09AM +0200, Pablo Neira Ayuso wrote:
> > On Tue, Sep 03, 2024 at 04:16:21AM +0200, Ahelenia Ziemiańska wrote:
> > > The manual says
> > >    COMMANDS
> > >        These options specify the particular operation to perform.
> > >        Only one of them can be specified at any given time.
> > > 
> > >        -L --dump
> > >               List connection tracking or expectation table
> > > 
> > > So, naturally, "conntrack -Lo extended" should work,
> > > but it doesn't, it's equivalent to "conntrack -L",
> > > and you need "conntrack -L -o extended".
> > > This violates user expectations (borne of the Utility Syntax Guidelines)
> > > and contradicts the manual.
> > > 
> > > optarg is unused, anyway. Unclear why any of these were :: at all?
> > Because this supports:
> >         -L
> >         -L conntrack
> >         -L expect
> Well that's not what :: does, though; we realise this, right?
> 
> "L::" means that getopt() will return
>   "-L", "conntrack" -> 'L',optarg=NULL
>   "-Lconntrack"     -> 'L',optarg="conntrack"
> and the parser for -L (&c.) doesn't... use optarg.

Are you sure it does not use optarg?

static unsigned int check_type(int argc, char *argv[])
{
        const char *table = get_optional_arg(argc, argv);

and get_optional_arg() uses optarg.

> You don't parse the filter (table name? idk.) with getopt at all;
> you can test this /right now/ by running precisely the thing you outlined:
>   # conntrack -L > /dev/null
>   conntrack v1.4.7 (conntrack-tools): 137 flow entries have been shown.
>   # conntrack -L expect > /dev/null
>   conntrack v1.4.7 (conntrack-tools): 0 expectations have been shown.
>   # conntrack -Lexpect > /dev/null
>   conntrack v1.4.7 (conntrack-tools): 152 flow entries have been shown.
> and getopt returns, respectively
>   'L',optarg=NULL
>   'L',optarg=NULL; argv[optind]="expect"
>   'L',optarg="expect"
> ...and once again you discard the optarg for 'L' &c.