Re: [PATCH] libxtables: xtables.c: Use getnameinfo()

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

On Sun, Dec 11, 2016 at 09:02:26PM +0100, Pablo Neira Ayuso wrote:
> On Fri, Dec 09, 2016 at 05:20:00PM +0530, Shyam Saini wrote:
> > Use getnameinfo() instead of deprecated gethostbyaddr()
> > 
> > Signed-off-by: Shyam Saini <mayhs11saini@gmail.com>
> > ---
> >  libxtables/xtables.c | 25 ++++++++++++++++++++-----
> >  1 file changed, 20 insertions(+), 5 deletions(-)
> > 
> > diff --git a/libxtables/xtables.c b/libxtables/xtables.c
> > index 921dfe9..338e325 100644
> > --- a/libxtables/xtables.c
> > +++ b/libxtables/xtables.c
> > @@ -1210,13 +1210,28 @@ const char *xtables_ipaddr_to_numeric(const struct in_addr *addrp)
> >  
> >  static const char *ipaddr_to_host(const struct in_addr *addr)
> >  {
> > -	struct hostent *host;
> > +	static char hostname[NI_MAXHOST];
> > +	struct sockaddr_in saddr;
> > +	int err;
> >  
> > -	host = gethostbyaddr(addr, sizeof(struct in_addr), AF_INET);
> > -	if (host == NULL)
> > -		return NULL;
> > +	memset(&saddr, 0, sizeof(struct sockaddr_in));
> > +	memcpy(&saddr.sin_addr, addr, sizeof(*addr));
> 
> You can skip this by perfoming C99 initialization, eg.
> 
>         struct sockaddr_in sin = { .sin_family = AF_INET, };
>         sin.sin_addr = *addr;

One more comment below.

> > +	saddr.sin_family = AF_INET;
> > +
> > +	err = getnameinfo((const void *)&saddr, sizeof(struct sockaddr_in),
> > +			              hostname, sizeof(hostname) - 1, NULL, 0, 0);
> > +
> > +	 if (err != 0) {
> > +#ifdef DEBUG
> > +		 fprintf(stderr,"IP2Name: %s\n",gai_strerror(err));
> > +#endif

I don't remember to have used this debugging this ever, probably it is
good to remove it.

> > +		 return NULL;
> > +	}
> >  
> > -	return host->h_name;
> > +#ifdef DEBUG
> > +		fprintf (stderr, "\naddr2host: %s\n", hostname);
> > +#endif
> > +		return hostname;
     ^^^^^^^^^^^

Minor nitpick: indentation is not correct here.