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

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

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;

> +	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
> +		 return NULL;
> +	}
>  
> -	return host->h_name;
> +#ifdef DEBUG
> +		fprintf (stderr, "\naddr2host: %s\n", hostname);
> +#endif
> +		return hostname;
>  }
>  
>  static const char *ipaddr_to_network(const struct in_addr *addr)
> -- 
> 2.7.4
> 
> --
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